init

src/app.h

@@ -0,0 +1,186 @@
+#pragma once
+
+#include <cstdint>
+#include <chrono>
+#include <filesystem>
+#include <map>
+#include <optional>
+#include <tuple>
+#include <string>
+#include <vector>
+
+#include "json.h"
+#include "models.h"
+#include "td_client.h"
+
+namespace telegram_tui {
+
+class App {
+  public:
+	App();
+	int run();
+
+  private:
+	void init_curses();
+	void shutdown_curses();
+	bool process_updates();
+	void handle_td_object(const json& object);
+	void handle_authorization_state();
+	void send_tdlib_parameters();
+	void send_check_phone_number();
+	void persist_config();
+	void request_chat_details(std::int64_t chat_id);
+	void set_open_chat(std::int64_t chat_id);
+	void open_forward_target_menu(std::int64_t source_chat_id, std::vector<std::int64_t> message_ids);
+	void start_input(InputMode mode, std::string prompt, bool hidden);
+	void clear_input();
+	void submit_input();
+	void send_message(std::int64_t chat_id, const std::string& text, std::optional<std::int64_t> reply_to_message_id = std::nullopt);
+	void forward_message(
+		std::int64_t source_chat_id,
+		const std::vector<std::int64_t>& message_ids,
+		std::int64_t target_chat_id);
+	void send_photo_message(
+		std::int64_t chat_id,
+		const std::string& photo_path,
+		const std::string& caption,
+		std::optional<std::int64_t> reply_to_message_id = std::nullopt);
+	bool preview_clipboard_photo_message(
+		std::int64_t chat_id,
+		const std::string& caption,
+		std::optional<std::int64_t> reply_to_message_id = std::nullopt);
+	void request_more_chats();
+	bool request_chat_history(std::int64_t chat_id, bool force);
+	bool request_open_chat_history(bool force);
+	void sync_chat_ids_from_response(const json& response);
+	void mark_chat_messages_as_read(std::int64_t chat_id);
+	void mark_message_as_read(std::int64_t chat_id, std::int64_t message_id);
+	void update_user_status(std::int64_t user_id, const json& status);
+	void upsert_user(const json& user);
+	void upsert_basic_group(const json& basic_group);
+	void upsert_supergroup(const json& supergroup);
+	void upsert_chat(const json& chat_object);
+	void apply_chat_position(ChatInfo& chat, const json& position);
+	void resort_chats();
+	void append_message(std::int64_t chat_id, MessageInfo message);
+	void remove_message(std::int64_t chat_id, std::int64_t message_id);
+	void merge_history(std::int64_t chat_id, const json& messages);
+	void update_attachment_file(const json& file);
+	void start_reply_to_latest_message();
+	void request_attachment_download(const AttachmentInfo& attachment, bool open_after_download);
+	void open_attachment(const AttachmentInfo& attachment);
+	void download_attachment(const AttachmentInfo& attachment);
+	void delete_attachment(const AttachmentInfo& attachment);
+	bool export_attachment_to_downloads(const AttachmentInfo& attachment);
+	bool play_video_attachment(const AttachmentInfo& attachment);
+	void refresh_attachment_viewer_content(const AttachmentInfo& attachment);
+	[[nodiscard]] std::vector<std::string> attachment_animation_frames(const AttachmentInfo& attachment) const;
+	bool advance_attachment_animation();
+	[[nodiscard]] std::string attachment_preview_path(const AttachmentInfo& attachment) const;
+	[[nodiscard]] bool has_inline_attachment_preview(const AttachmentInfo& attachment, int width, int height) const;
+	void clear_attachment_preview_graphics();
+	void render_attachment_preview_graphics(int top, int left, int width, int height);
+	void reset_attachment_viewer_send_preview();
+	[[nodiscard]] std::vector<std::int64_t> forward_target_chat_ids() const;
+	[[nodiscard]] std::optional<AttachmentInfo> selected_attachment() const;
+	[[nodiscard]] std::string render_attachment_preview(const AttachmentInfo& attachment, int width, int height) const;
+	[[nodiscard]] std::string build_attachment_preview_graphics(const AttachmentInfo& attachment, int width, int height) const;
+	[[nodiscard]] std::tuple<bool, std::int64_t, std::string> parse_compose_command(const std::string& value) const;
+	[[nodiscard]] std::optional<std::vector<std::int64_t>> parse_forward_command(const std::string& value) const;
+	[[nodiscard]] std::optional<std::size_t> find_message_index(const ChatInfo& chat, std::int64_t message_id) const;
+	[[nodiscard]] std::string format_message_ref(const ChatInfo& chat, std::int64_t message_id) const;
+	[[nodiscard]] std::string sender_label(const json& sender) const;
+	[[nodiscard]] std::string user_status_label(std::int64_t user_id) const;
+	[[nodiscard]] std::string forward_origin_label(const json& forward_info) const;
+	[[nodiscard]] std::string via_bot_label(std::int64_t via_bot_user_id) const;
+	[[nodiscard]] std::string preview_message(const json& message) const;
+	[[nodiscard]] std::optional<AttachmentInfo> parse_attachment(const json& content) const;
+	[[nodiscard]] std::string content_to_text(const json& content, bool decorate) const;
+	[[nodiscard]] MessageInfo parse_message(const json& message) const;
+	[[nodiscard]] std::string format_open_chat_header(const ChatInfo& chat) const;
+	void handle_key(int ch);
+	void handle_wide_char(wint_t ch);
+	void handle_input_key(int ch);
+	void handle_forward_target_menu_key(int ch);
+	void handle_help_menu_key(int ch);
+	void handle_attachments_menu_key(int ch);
+	void handle_attachment_action_menu_key(int ch);
+	void handle_attachment_viewer_key(int ch);
+	void draw();
+	void init_colors();
+	void draw_chat_pane(int top, int height, int width);
+	void draw_message_pane(int top, int height, int left, int width);
+	void draw_help_menu(int height, int width);
+	void draw_forward_target_menu(int height, int width);
+	void draw_attachments_menu(int height, int width);
+	void draw_attachment_action_menu(int height, int width);
+	void draw_attachment_viewer(int height, int width);
+	[[nodiscard]] std::optional<std::int64_t> highlighted_chat_id() const;
+	[[nodiscard]] std::optional<std::int64_t> open_chat_id() const;
+	[[nodiscard]] std::string current_auth_label() const;
+
+	TdClient td_;
+	std::map<std::int64_t, UserInfo> users_;
+	std::map<std::int64_t, ChatInfo> chats_;
+	std::vector<std::int64_t> sorted_chat_ids_;
+
+	std::filesystem::path database_dir_;
+	std::filesystem::path files_dir_;
+
+	bool running_ = true;
+	bool authorized_ = false;
+	bool attachments_menu_open_ = false;
+	bool attachment_action_menu_open_ = false;
+	bool attachment_viewer_open_ = false;
+	bool forward_target_menu_open_ = false;
+	bool help_menu_open_ = false;
+	bool input_hidden_ = false;
+	bool auto_reload_chat_history_ = false;
+	bool use_test_dc_ = false;
+
+	FocusPane focus_ = FocusPane::Chats;
+	InputMode input_mode_ = InputMode::None;
+
+	int selected_chat_index_ = 0;
+	int message_scroll_ = 0;
+	int attachment_category_index_ = 0;
+	int attachment_selection_index_ = 0;
+	int attachment_action_index_ = 0;
+	int attachment_viewer_scroll_ = 0;
+	int forward_target_index_ = 0;
+	std::int64_t open_chat_id_ = 0;
+	std::int64_t tdlib_open_chat_id_ = 0;
+	std::int64_t my_user_id_ = 0;
+	std::int64_t forward_source_chat_id_ = 0;
+	std::size_t input_cursor_ = 0;
+
+	std::string api_id_;
+	std::string api_hash_;
+	std::string phone_number_;
+	std::string pending_first_name_;
+
+	std::string input_prompt_;
+	std::string input_buffer_;
+	std::string status_line_ = "Starting TDLib...";
+	std::string attachment_preview_graphics_data_;
+	std::string attachment_viewer_title_;
+	std::string attachment_preview_signature_;
+	std::vector<std::string> attachment_viewer_lines_;
+	std::vector<std::string> attachment_viewer_animation_frames_;
+	json authorization_state_ = json::object();
+	std::optional<AttachmentInfo> pending_attachment_open_;
+	std::optional<AttachmentInfo> pending_attachment_download_;
+	std::optional<AttachmentInfo> attachment_viewer_attachment_;
+	std::optional<std::int64_t> attachment_viewer_send_reply_to_message_id_;
+	std::chrono::steady_clock::time_point attachment_viewer_next_frame_at_{};
+	std::int64_t attachment_viewer_send_chat_id_ = 0;
+	bool attachment_preview_graphics_visible_ = false;
+	bool attachment_preview_graphics_is_sixel_ = false;
+	bool attachment_viewer_send_on_enter_ = false;
+	bool attachment_viewer_is_animated_ = false;
+	std::size_t attachment_viewer_frame_index_ = 0;
+	std::string attachment_viewer_send_caption_;
+	std::vector<std::int64_t> forward_message_ids_;
+};
+
+}  // namespace telegram_tui

src/app_auth.cpp

@@ -0,0 +1,669 @@
+#include "app.h"
+
+#include <array>
+#include <set>
+#include <cstdio>
+#include <cstdlib>
+#include <filesystem>
+#include <sstream>
+
+#include <curses.h>
+
+#include "util.h"
+
+namespace telegram_tui {
+
+namespace {
+
+struct ClipboardImageType {
+	const char* mime = "";
+	const char* extension = "";
+};
+
+constexpr std::array<ClipboardImageType, 5> kClipboardImageTypes = {{
+	{"image/png", ".png"},
+	{"image/jpeg", ".jpg"},
+	{"image/webp", ".webp"},
+	{"image/bmp", ".bmp"},
+	{"image/tiff", ".tiff"},
+}};
+
+std::string shell_quote(const std::string& value) {
+	std::string quoted = "'";
+	for (char ch : value) {
+		if (ch == '\'') {
+			quoted += "'\\''";
+		} else {
+			quoted.push_back(ch);
+		}
+	}
+	quoted.push_back('\'');
+	return quoted;
+}
+
+std::string run_command_capture(const std::string& command) {
+	FILE* pipe = popen(command.c_str(), "r");
+	if (pipe == nullptr) {
+		return {};
+	}
+
+	std::string output;
+	char buffer[4096];
+	while (std::fgets(buffer, sizeof(buffer), pipe) != nullptr) {
+		output += buffer;
+	}
+	if (pclose(pipe) != 0) {
+		return {};
+	}
+	return output;
+}
+
+bool command_exists(const char* command) {
+	const std::string resolved = run_command_capture("command -v " + std::string(command) + " 2>/dev/null");
+	return !trim_copy(resolved).empty();
+}
+
+std::string clipboard_capture_command(const std::string& mime_type, const std::string& destination_path) {
+	if (command_exists("wl-paste")) {
+		return "wl-paste --no-newline --type " + shell_quote(mime_type) + " > " +
+			shell_quote(destination_path) + " 2>/dev/null";
+	}
+	if (command_exists("xclip")) {
+		return "xclip -selection clipboard -t " + shell_quote(mime_type) + " -o > " +
+			shell_quote(destination_path) + " 2>/dev/null";
+	}
+	if (command_exists("pngpaste") && mime_type == "image/png") {
+		return "pngpaste " + shell_quote(destination_path) + " >/dev/null 2>&1";
+	}
+	return {};
+}
+
+std::optional<ClipboardImageType> detect_clipboard_image_type() {
+	if (command_exists("wl-paste")) {
+		const std::string types_output = run_command_capture("wl-paste --list-types 2>/dev/null");
+		for (const auto& type : kClipboardImageTypes) {
+			if (types_output.find(type.mime) != std::string::npos) {
+				return type;
+			}
+		}
+	}
+	if (command_exists("xclip")) {
+		const std::string targets_output =
+			run_command_capture("xclip -selection clipboard -t TARGETS -o 2>/dev/null");
+		for (const auto& type : kClipboardImageTypes) {
+			if (targets_output.find(type.mime) != std::string::npos) {
+				return type;
+			}
+		}
+	}
+	if (command_exists("pngpaste")) {
+		return ClipboardImageType{"image/png", ".png"};
+	}
+	return std::nullopt;
+}
+
+std::optional<std::string> parse_clipboard_compose_command(const std::string& value) {
+	static constexpr std::array<const char*, 3> kPrefixes = {">paste", ">clip", ">screenshot"};
+	for (const char* prefix : kPrefixes) {
+		if (value == prefix) {
+			return std::string();
+		}
+		const std::string with_space = std::string(prefix) + " ";
+		if (value.rfind(with_space, 0) == 0) {
+			return trim_copy(value.substr(with_space.size()));
+		}
+	}
+	return std::nullopt;
+}
+
+std::optional<std::string> strip_forward_prefix(const std::string& value) {
+	static constexpr std::array<const char*, 3> kPrefixes = {">f", ">fw", ">forward"};
+	for (const char* prefix : kPrefixes) {
+		if (value == prefix) {
+			return std::string();
+		}
+		const std::string with_space = std::string(prefix) + " ";
+		if (value.rfind(with_space, 0) == 0) {
+			return trim_copy(value.substr(with_space.size()));
+		}
+	}
+	return std::nullopt;
+}
+
+json markdown_formatted_text(TdClient& td, const std::string& text) {
+	json formatted_text = {
+		{"@type", "formattedText"},
+		{"text", text},
+		{"entities", json::array()},
+	};
+	if (const auto parsed = td.execute({
+			{"@type", "parseMarkdown"},
+			{"text", formatted_text},
+		});
+		parsed.has_value() && safe_string(*parsed, "@type") == "formattedText") {
+		formatted_text = *parsed;
+	}
+	return formatted_text;
+}
+
+}  // namespace
+
+void App::handle_authorization_state() {
+	const std::string type = safe_string(authorization_state_, "@type");
+	if (type == "authorizationStateWaitTdlibParameters") {
+		if (api_id_.empty()) {
+			start_input(InputMode::ApiId, "Telegram API ID", false);
+			status_line_ = "Enter your Telegram application API ID.";
+			return;
+		}
+		if (api_hash_.empty()) {
+			start_input(InputMode::ApiHash, "Telegram API hash", false);
+			status_line_ = "Enter your Telegram application API hash.";
+			return;
+		}
+		send_tdlib_parameters();
+		return;
+	}
+	if (type == "authorizationStateWaitPhoneNumber") {
+		if (phone_number_.empty()) {
+			start_input(InputMode::PhoneNumber, "Phone number", false);
+			status_line_ = "Enter phone number for Telegram account.";
+			return;
+		}
+		send_check_phone_number();
+		return;
+	}
+	if (type == "authorizationStateWaitEncryptionKey") {
+		td_.send({
+			{"@type", "checkDatabaseEncryptionKey"},
+			{"encryption_key", ""},
+		});
+		status_line_ = "Unlocking local database...";
+		return;
+	}
+	if (type == "authorizationStateWaitCode") {
+		start_input(InputMode::AuthCode, "Login code", false);
+		status_line_ = "Enter code Telegram sent.";
+		return;
+	}
+	if (type == "authorizationStateWaitPassword") {
+		start_input(InputMode::Password, "2FA password", true);
+		status_line_ = "Two-step verification enabled.";
+		return;
+	}
+	if (type == "authorizationStateWaitRegistration") {
+		if (pending_first_name_.empty()) {
+			start_input(InputMode::FirstName, "First name", false);
+			status_line_ = "New account. Enter first name.";
+		} else {
+			start_input(InputMode::LastName, "Last name", false);
+			status_line_ = "Enter optional last name.";
+		}
+		return;
+	}
+	if (type == "authorizationStateReady") {
+		authorized_ = true;
+		input_mode_ = InputMode::None;
+		status_line_ = "Authorized. Loading chats.";
+		td_.send({
+			{"@type", "getMe"},
+			{"@extra", "getMe"},
+		});
+		request_more_chats();
+		if (!open_chat_id().has_value()) {
+			const auto chat_id = highlighted_chat_id();
+			if (chat_id.has_value()) {
+				set_open_chat(*chat_id);
+			}
+		}
+		request_open_chat_history(false);
+		return;
+	}
+	if (type == "authorizationStateLoggingOut") {
+		authorized_ = false;
+		status_line_ = "Logging out...";
+		return;
+	}
+	if (type == "authorizationStateClosed") {
+		authorized_ = false;
+		status_line_ = "TDLib session closed.";
+	}
+}
+
+void App::send_tdlib_parameters() {
+	if (!is_decimal_number(api_id_)) {
+		start_input(InputMode::ApiId, "Telegram API ID", false);
+		status_line_ = "Telegram API ID must be numeric.";
+		return;
+	}
+
+	status_line_ = "Sending TDLib parameters...";
+	td_.send({
+		{"@type", "setTdlibParameters"},
+		{"use_test_dc", use_test_dc_},
+		{"database_directory", database_dir_.string()},
+		{"files_directory", files_dir_.string()},
+		{"database_encryption_key", ""},
+		{"use_file_database", true},
+		{"use_chat_info_database", true},
+		{"use_message_database", true},
+		{"use_secret_chats", true},
+		{"api_id", std::stoi(api_id_)},
+		{"api_hash", api_hash_},
+		{"system_language_code", "en"},
+		{"device_model", "shinoa"},
+		{"system_version", "Linux"},
+		{"application_version", "0.1.0"},
+		{"enable_storage_optimizer", true},
+		{"ignore_file_names", false},
+	});
+}
+
+void App::send_check_phone_number() {
+	status_line_ = "Requesting login code...";
+	td_.send({
+		{"@type", "setAuthenticationPhoneNumber"},
+		{"phone_number", phone_number_},
+		{"settings", {{"@type", "phoneNumberAuthenticationSettings"}}},
+	});
+}
+
+void App::persist_config() {
+	if (!save_app_config(StoredConfig{api_id_, api_hash_, auto_reload_chat_history_})) {
+		status_line_ = "Failed to save config locally.";
+	}
+}
+
+void App::request_chat_details(std::int64_t chat_id) {
+	auto chat_it = chats_.find(chat_id);
+	if (chat_it == chats_.end()) {
+		return;
+	}
+
+	ChatInfo& chat = chat_it->second;
+	if (chat.details_requested) {
+		return;
+	}
+
+	if (chat.private_user_id != 0) {
+		td_.send({
+			{"@type", "getUser"},
+			{"user_id", chat.private_user_id},
+		});
+		chat.details_requested = true;
+		return;
+	}
+
+	if (chat.basic_group_id != 0) {
+		td_.send({
+			{"@type", "getBasicGroup"},
+			{"basic_group_id", chat.basic_group_id},
+		});
+		chat.details_requested = true;
+		return;
+	}
+
+	if (chat.supergroup_id != 0) {
+		td_.send({
+			{"@type", "getSupergroup"},
+			{"supergroup_id", chat.supergroup_id},
+		});
+		chat.details_requested = true;
+	}
+}
+
+void App::start_input(InputMode mode, std::string prompt, bool hidden) {
+	input_mode_ = mode;
+	input_prompt_ = std::move(prompt);
+	input_hidden_ = hidden;
+	if (mode != InputMode::Compose) {
+		input_buffer_.clear();
+	}
+	input_cursor_ = input_buffer_.size();
+	curs_set(1);
+}
+
+void App::clear_input() {
+	input_mode_ = InputMode::None;
+	input_prompt_.clear();
+	input_buffer_.clear();
+	input_cursor_ = 0;
+	input_hidden_ = false;
+	curs_set(0);
+}
+
+void App::submit_input() {
+	const std::string value = trim_copy(input_buffer_);
+	if (value.empty()) {
+		status_line_ = "Input cannot be empty.";
+		return;
+	}
+
+	const InputMode mode = input_mode_;
+	if (mode == InputMode::ApiId && !is_decimal_number(value)) {
+		status_line_ = "Telegram API ID must be numeric.";
+		return;
+	}
+	clear_input();
+
+	if (mode == InputMode::Compose) {
+		const auto chat_id = open_chat_id();
+		if (!chat_id.has_value()) {
+			status_line_ = "Open chat first.";
+			return;
+		}
+		if (const auto message_ids = parse_forward_command(value); message_ids.has_value()) {
+			open_forward_target_menu(*chat_id, *message_ids);
+			return;
+		}
+		const auto [is_reply, reply_to_message_id, text] = parse_compose_command(value);
+		if (const auto clipboard_caption = parse_clipboard_compose_command(text); clipboard_caption.has_value()) {
+			preview_clipboard_photo_message(
+				*chat_id,
+				*clipboard_caption,
+				is_reply ? std::optional<std::int64_t>(reply_to_message_id) : std::nullopt);
+			return;
+		}
+		if (text.empty()) {
+			status_line_ = "Reply text cannot be empty.";
+			return;
+		}
+		send_message(*chat_id, text, is_reply ? std::optional<std::int64_t>(reply_to_message_id) : std::nullopt);
+		return;
+	}
+	if (mode == InputMode::ApiId) {
+		api_id_ = value;
+		persist_config();
+		if (api_hash_.empty()) {
+			start_input(InputMode::ApiHash, "Telegram API hash", false);
+		} else {
+			send_tdlib_parameters();
+		}
+		return;
+	}
+	if (mode == InputMode::ApiHash) {
+		api_hash_ = value;
+		persist_config();
+		send_tdlib_parameters();
+		return;
+	}
+	if (mode == InputMode::PhoneNumber) {
+		phone_number_ = value;
+		send_check_phone_number();
+		return;
+	}
+	if (mode == InputMode::AuthCode) {
+		td_.send({
+			{"@type", "checkAuthenticationCode"},
+			{"code", value},
+		});
+		status_line_ = "Submitting code...";
+		return;
+	}
+	if (mode == InputMode::Password) {
+		td_.send({
+			{"@type", "checkAuthenticationPassword"},
+			{"password", value},
+		});
+		status_line_ = "Submitting password...";
+		return;
+	}
+	if (mode == InputMode::FirstName) {
+		pending_first_name_ = value;
+		start_input(InputMode::LastName, "Last name", false);
+		status_line_ = "Enter last name or - for none.";
+		return;
+	}
+	if (mode == InputMode::LastName) {
+		const std::string last_name = value == "-" ? "" : value;
+		td_.send({
+			{"@type", "registerUser"},
+			{"first_name", pending_first_name_},
+			{"last_name", last_name},
+		});
+		pending_first_name_.clear();
+		status_line_ = "Registering account...";
+	}
+}
+
+void App::send_message(
+	std::int64_t chat_id,
+	const std::string& text,
+	std::optional<std::int64_t> reply_to_message_id) {
+	json formatted_text = markdown_formatted_text(td_, text);
+
+	json request = {
+		{"@type", "sendMessage"},
+		{"chat_id", chat_id},
+		{"input_message_content",
+			{
+				{"@type", "inputMessageText"},
+				{"text", formatted_text},
+				{"clear_draft", true},
+			}},
+	};
+	if (reply_to_message_id.has_value()) {
+		request["reply_to"] = {
+			{"@type", "inputMessageReplyToMessage"},
+			{"message_id", *reply_to_message_id},
+		};
+	}
+	td_.send(request);
+	status_line_ = "Message queued.";
+}
+
+void App::forward_message(
+	std::int64_t source_chat_id,
+	const std::vector<std::int64_t>& message_ids,
+	std::int64_t target_chat_id) {
+	td_.send({
+		{"@type", "forwardMessages"},
+		{"chat_id", target_chat_id},
+		{"from_chat_id", source_chat_id},
+		{"message_ids", message_ids},
+		{"send_copy", false},
+		{"remove_caption", false},
+	});
+	status_line_ = message_ids.size() == 1 ? "Forwarding message..." : "Forwarding messages...";
+}
+
+void App::send_photo_message(
+	std::int64_t chat_id,
+	const std::string& photo_path,
+	const std::string& caption,
+	std::optional<std::int64_t> reply_to_message_id) {
+	json request = {
+		{"@type", "sendMessage"},
+		{"chat_id", chat_id},
+		{"input_message_content",
+			{
+				{"@type", "inputMessagePhoto"},
+				{"photo", {{"@type", "inputFileLocal"}, {"path", photo_path}}},
+				{"thumbnail", nullptr},
+				{"video", nullptr},
+				{"added_sticker_file_ids", json::array()},
+				{"width", 0},
+				{"height", 0},
+				{"caption", markdown_formatted_text(td_, caption)},
+				{"show_caption_above_media", false},
+				{"self_destruct_type", nullptr},
+				{"has_spoiler", false},
+			}},
+	};
+	if (reply_to_message_id.has_value()) {
+		request["reply_to"] = {
+			{"@type", "inputMessageReplyToMessage"},
+			{"message_id", *reply_to_message_id},
+		};
+	}
+	td_.send(request);
+	status_line_ = "Photo queued.";
+}
+
+bool App::preview_clipboard_photo_message(
+	std::int64_t chat_id,
+	const std::string& caption,
+	std::optional<std::int64_t> reply_to_message_id) {
+	const auto clipboard_type = detect_clipboard_image_type();
+	if (!clipboard_type.has_value()) {
+		status_line_ = "Clipboard doesn't contain an image, or no clipboard tool is available.";
+		return false;
+	}
+
+	const std::filesystem::path clipboard_dir = files_dir_ / "clipboard";
+	try {
+		std::filesystem::create_directories(clipboard_dir);
+	} catch (const std::exception& error) {
+		status_line_ = std::string("Failed to prepare clipboard cache: ") + error.what();
+		return false;
+	}
+
+	std::filesystem::path image_path;
+	for (std::uint64_t index = 0; index < 1024; ++index) {
+		const std::filesystem::path candidate =
+			clipboard_dir / ("clipboard-" + std::to_string(std::time(nullptr)) + "-" + std::to_string(index) +
+				clipboard_type->extension);
+		if (!std::filesystem::exists(candidate)) {
+			image_path = candidate;
+			break;
+		}
+	}
+	if (image_path.empty()) {
+		status_line_ = "Failed to allocate a clipboard image path.";
+		return false;
+	}
+
+	const std::string command = clipboard_capture_command(clipboard_type->mime, image_path.string());
+	if (command.empty() || std::system(command.c_str()) != 0 || !std::filesystem::exists(image_path)) {
+		status_line_ = "Failed to read image data from the clipboard.";
+		return false;
+	}
+
+	try {
+		if (std::filesystem::file_size(image_path) == 0) {
+			std::filesystem::remove(image_path);
+			status_line_ = "Clipboard image is empty.";
+			return false;
+		}
+	} catch (const std::exception&) {
+		status_line_ = "Clipboard image couldn't be validated.";
+		return false;
+	}
+
+	AttachmentInfo attachment;
+	attachment.type = AttachmentType::Photo;
+	attachment.name = image_path.filename().string();
+	attachment.size_bytes = static_cast<std::int64_t>(std::filesystem::file_size(image_path));
+	attachment.local_path = image_path.string();
+	attachment.is_downloaded = true;
+
+	attachment_viewer_attachment_ = attachment;
+	attachment_viewer_title_ = "Clipboard photo: " + attachment.name;
+	attachment_viewer_animation_frames_.clear();
+	attachment_viewer_is_animated_ = false;
+	attachment_viewer_frame_index_ = 0;
+	attachment_viewer_scroll_ = 0;
+	attachment_preview_signature_.clear();
+	attachment_viewer_send_on_enter_ = true;
+	attachment_viewer_send_chat_id_ = chat_id;
+	attachment_viewer_send_reply_to_message_id_ = reply_to_message_id;
+	attachment_viewer_send_caption_ = caption;
+	refresh_attachment_viewer_content(attachment);
+	attachment_viewer_open_ = true;
+	status_line_ = caption.empty()
+		? "Clipboard image preview. Press Enter to send."
+		: "Clipboard image preview with caption. Press Enter to send.";
+	return true;
+}
+
+std::optional<std::vector<std::int64_t>> App::parse_forward_command(const std::string& value) const {
+	const auto remainder = strip_forward_prefix(value);
+	if (!remainder.has_value()) {
+		return std::nullopt;
+	}
+
+	const auto chat_id = open_chat_id();
+	if (!chat_id.has_value()) {
+		return std::vector<std::int64_t>{};
+	}
+	const auto chat_it = chats_.find(*chat_id);
+	if (chat_it == chats_.end()) {
+		return std::vector<std::int64_t>{};
+	}
+
+	const ChatInfo& chat = chat_it->second;
+	if (remainder->empty()) {
+		return std::vector<std::int64_t>{};
+	}
+
+	auto resolve_message_ref = [&](std::int64_t ref) -> std::int64_t {
+		if (ref > 0 && ref <= static_cast<std::int64_t>(chat.messages.size())) {
+			return chat.messages[static_cast<std::size_t>(ref - 1)].id;
+		}
+		for (const auto& message : chat.messages) {
+			if (message.id == ref) {
+				return message.id;
+			}
+		}
+		return 0;
+	};
+
+	std::string normalized = *remainder;
+	for (char& ch : normalized) {
+		if (ch == ',') {
+			ch = ' ';
+		}
+	}
+
+	std::set<std::int64_t> unique_message_ids;
+	std::stringstream stream(normalized);
+	std::string token;
+	while (stream >> token) {
+		const auto dash = token.find('-');
+		if (dash != std::string::npos) {
+			const std::string start_text = token.substr(0, dash);
+			const std::string end_text = token.substr(dash + 1);
+			if (!is_decimal_number(start_text) || !is_decimal_number(end_text)) {
+				return std::vector<std::int64_t>{};
+			}
+			std::int64_t start_value = 0;
+			std::int64_t end_value = 0;
+			try {
+				start_value = std::stoll(start_text);
+				end_value = std::stoll(end_text);
+			} catch (...) {
+				return std::vector<std::int64_t>{};
+			}
+			if (start_value > end_value) {
+				std::swap(start_value, end_value);
+			}
+			for (std::int64_t ref = start_value; ref <= end_value; ++ref) {
+				const std::int64_t message_id = resolve_message_ref(ref);
+				if (message_id == 0) {
+					return std::vector<std::int64_t>{};
+				}
+				unique_message_ids.insert(message_id);
+			}
+			continue;
+		}
+
+		if (!is_decimal_number(token)) {
+			return std::vector<std::int64_t>{};
+		}
+		std::int64_t parsed_value = 0;
+		try {
+			parsed_value = std::stoll(token);
+		} catch (...) {
+			return std::vector<std::int64_t>{};
+		}
+		const std::int64_t message_id = resolve_message_ref(parsed_value);
+		if (message_id == 0) {
+			return std::vector<std::int64_t>{};
+		}
+		unique_message_ids.insert(message_id);
+	}
+
+	return std::vector<std::int64_t>(unique_message_ids.begin(), unique_message_ids.end());
+}
+
+}  // namespace telegram_tui

src/app_chats.cpp

@@ -0,0 +1,269 @@
+#include "app.h"
+
+#include <algorithm>
+
+#include "util.h"
+
+namespace telegram_tui {
+
+namespace {
+
+std::string join_with_separator_local(const std::vector<std::string>& parts, const char* separator) {
+	std::string joined;
+	for (const auto& part : parts) {
+		if (part.empty()) {
+			continue;
+		}
+		if (!joined.empty()) {
+			joined += separator;
+		}
+		joined += part;
+	}
+	return joined;
+}
+
+std::string format_user_status(const json& status) {
+	const std::string type = safe_string(status, "@type");
+	if (type == "userStatusOnline") {
+		return "online";
+	}
+	if (type == "userStatusOffline") {
+		const std::int32_t was_online = safe_i32(status, "was_online");
+		return was_online > 0 ? ("last seen " + format_datetime(was_online)) : "offline";
+	}
+	if (type == "userStatusRecently") {
+		return "last seen recently";
+	}
+	if (type == "userStatusLastWeek") {
+		return "last seen within a week";
+	}
+	if (type == "userStatusLastMonth") {
+		return "last seen within a month";
+	}
+	return {};
+}
+
+std::string primary_username(const json& object) {
+	const json usernames = object.value("usernames", json::object());
+	const json active_usernames = usernames.value("active_usernames", json::array());
+	if (active_usernames.is_array()) {
+		for (const auto& username : active_usernames) {
+			if (username.is_string()) {
+				const std::string value = username.get<std::string>();
+				if (!value.empty()) {
+					return value;
+				}
+			}
+		}
+	}
+	return safe_string(object, "username");
+}
+
+}  // namespace
+
+void App::update_user_status(std::int64_t user_id, const json& status) {
+	UserInfo& info = users_[user_id];
+	info.id = user_id;
+	info.status = format_user_status(status);
+}
+
+void App::upsert_user(const json& user) {
+	if (user.is_null()) {
+		return;
+	}
+	UserInfo& info = users_[safe_i64(user, "id")];
+	info.id = safe_i64(user, "id");
+	info.first_name = safe_string(user, "first_name");
+	info.last_name = safe_string(user, "last_name");
+	info.username = primary_username(user);
+	info.status = format_user_status(user.value("status", json::object()));
+}
+
+void App::upsert_basic_group(const json& basic_group) {
+	if (basic_group.is_null()) {
+		return;
+	}
+	const std::int64_t basic_group_id = safe_i64(basic_group, "id");
+	const std::int32_t member_count = safe_i32(basic_group, "member_count");
+	for (auto& [chat_id, chat] : chats_) {
+		if (chat.basic_group_id != basic_group_id) {
+			continue;
+		}
+		chat.id = chat_id;
+		chat.username.clear();
+		chat.member_count = member_count;
+		chat.has_member_count = true;
+	}
+}
+
+void App::upsert_supergroup(const json& supergroup) {
+	if (supergroup.is_null()) {
+		return;
+	}
+	const std::int64_t supergroup_id = safe_i64(supergroup, "id");
+	const std::int32_t member_count = safe_i32(supergroup, "member_count");
+	const bool is_channel = supergroup.value("is_channel", false);
+	const std::string username = primary_username(supergroup);
+	for (auto& [chat_id, chat] : chats_) {
+		if (chat.supergroup_id != supergroup_id) {
+			continue;
+		}
+		chat.id = chat_id;
+		chat.is_channel = is_channel;
+		chat.username = username;
+		chat.member_count = member_count;
+		chat.has_member_count = true;
+	}
+}
+
+void App::upsert_chat(const json& chat_object) {
+	if (chat_object.is_null()) {
+		return;
+	}
+
+	const std::int64_t chat_id = safe_i64(chat_object, "id");
+	ChatInfo& chat = chats_[chat_id];
+	chat.id = chat_id;
+	if (chat_object.contains("title")) {
+		chat.title = safe_string(chat_object, "title");
+	}
+	const json type = chat_object.value("type", json::object());
+	const std::string type_name = safe_string(type, "@type");
+	const std::int64_t previous_private_user_id = chat.private_user_id;
+	const std::int64_t previous_basic_group_id = chat.basic_group_id;
+	const std::int64_t previous_supergroup_id = chat.supergroup_id;
+	chat.private_user_id = 0;
+	chat.basic_group_id = 0;
+	chat.supergroup_id = 0;
+	chat.is_channel = false;
+	if (type_name == "chatTypePrivate" || type_name == "chatTypeSecret") {
+		chat.private_user_id = safe_i64(type, "user_id");
+		chat.username.clear();
+		chat.has_member_count = false;
+		chat.has_online_member_count = false;
+		chat.member_count = 0;
+		chat.online_member_count = 0;
+	} else if (type_name == "chatTypeBasicGroup") {
+		chat.basic_group_id = safe_i64(type, "basic_group_id");
+		chat.username.clear();
+	} else if (type_name == "chatTypeSupergroup") {
+		chat.supergroup_id = safe_i64(type, "supergroup_id");
+		chat.is_channel = type.value("is_channel", false);
+		if (chat.supergroup_id != previous_supergroup_id) {
+			chat.username.clear();
+		}
+	} else {
+		chat.username.clear();
+	}
+	if (chat.private_user_id != previous_private_user_id ||
+		chat.basic_group_id != previous_basic_group_id ||
+		chat.supergroup_id != previous_supergroup_id) {
+		chat.details_requested = false;
+	}
+	chat.unread_count = safe_i32(chat_object, "unread_count");
+	chat.last_read_inbox_message_id = safe_i64(chat_object, "last_read_inbox_message_id");
+	chat.last_read_outbox_message_id = safe_i64(chat_object, "last_read_outbox_message_id");
+	if (chat_object.contains("last_message")) {
+		chat.last_message_preview = preview_message(chat_object.at("last_message"));
+	}
+	if (chat_object.contains("positions") && chat_object.at("positions").is_array()) {
+		chat.in_main_list = false;
+		chat.main_order = 0;
+		for (const auto& position : chat_object.at("positions")) {
+			apply_chat_position(chat, position);
+		}
+	}
+	if (open_chat_id_ == chat.id) {
+		request_chat_details(chat.id);
+	}
+	resort_chats();
+}
+
+void App::apply_chat_position(ChatInfo& chat, const json& position) {
+	if (!position.is_object()) {
+		return;
+	}
+
+	const json chat_list = position.value("list", json::object());
+	if (safe_string(chat_list, "@type") != "chatListMain") {
+		return;
+	}
+	chat.in_main_list = true;
+	chat.main_order = safe_i64(position, "order");
+}
+
+void App::resort_chats() {
+	if (sorted_chat_ids_.empty()) {
+		for (const auto& [chat_id, chat] : chats_) {
+			if (chat.in_main_list) {
+				sorted_chat_ids_.push_back(chat_id);
+			}
+		}
+	} else {
+		for (const auto& [chat_id, chat] : chats_) {
+			if (!chat.in_main_list) {
+				continue;
+			}
+			if (std::find(sorted_chat_ids_.begin(), sorted_chat_ids_.end(), chat_id) == sorted_chat_ids_.end()) {
+				sorted_chat_ids_.push_back(chat_id);
+			}
+		}
+	}
+
+	std::stable_sort(sorted_chat_ids_.begin(), sorted_chat_ids_.end(),
+		[&](std::int64_t lhs, std::int64_t rhs) {
+			const auto left_it = chats_.find(lhs);
+			const auto right_it = chats_.find(rhs);
+			const bool left_has_order = left_it != chats_.end() && left_it->second.in_main_list && left_it->second.main_order > 0;
+			const bool right_has_order = right_it != chats_.end() && right_it->second.in_main_list && right_it->second.main_order > 0;
+			if (left_has_order != right_has_order) {
+				return left_has_order;
+			}
+			if (left_has_order && right_has_order && left_it->second.main_order != right_it->second.main_order) {
+				return left_it->second.main_order > right_it->second.main_order;
+			}
+			return false;
+		});
+
+	if (selected_chat_index_ >= static_cast<int>(sorted_chat_ids_.size())) {
+		selected_chat_index_ = std::max(0, static_cast<int>(sorted_chat_ids_.size()) - 1);
+	}
+}
+
+std::string App::format_open_chat_header(const ChatInfo& chat) const {
+	std::vector<std::string> parts;
+	if (!chat.title.empty()) {
+		parts.push_back(chat.title);
+	}
+
+	if (chat.private_user_id != 0) {
+		const auto user_it = users_.find(chat.private_user_id);
+		if (user_it != users_.end()) {
+			if (!user_it->second.username.empty()) {
+				parts.push_back("@" + user_it->second.username);
+			}
+			const std::string status = user_status_label(chat.private_user_id);
+			if (!status.empty()) {
+				parts.push_back(status);
+			}
+			parts.push_back("id:" + std::to_string(user_it->second.id));
+		} else {
+			parts.push_back("id:" + std::to_string(chat.private_user_id));
+		}
+		return join_with_separator_local(parts, " | ");
+	}
+	if (!chat.username.empty()) {
+		parts.push_back("@" + chat.username);
+	}
+	if (chat.has_member_count) {
+		parts.push_back(
+			std::to_string(chat.member_count) + " " + (chat.is_channel ? "subscribers" : "members"));
+	}
+	if (!chat.is_channel && chat.has_online_member_count) {
+		parts.push_back(std::to_string(chat.online_member_count) + " online");
+	}
+	parts.push_back("id:" + std::to_string(chat.id));
+	return join_with_separator_local(parts, " | ");
+}
+
+}  // namespace telegram_tui

src/app_state.cpp

@@ -0,0 +1,545 @@
+#include "app.h"
+
+#include <algorithm>
+#include <set>
+
+#include "util.h"
+
+namespace telegram_tui {
+
+namespace {
+
+std::string format_download_progress(std::int64_t downloaded_size, std::int64_t size_bytes, bool is_downloaded) {
+	if (is_downloaded) {
+		return "100%";
+	}
+	if (size_bytes > 0) {
+		const auto downloaded = std::min(downloaded_size, size_bytes);
+		return std::to_string(static_cast<int>((downloaded * 100) / size_bytes)) + "% " +
+			format_file_size(downloaded) + "/" + format_file_size(size_bytes);
+	}
+	return format_file_size(downloaded_size);
+}
+
+}  // namespace
+
+bool App::process_updates() {
+	bool changed = false;
+	while (true) {
+		auto update = td_.receive(0.0);
+		if (!update.has_value()) {
+			break;
+		}
+		changed = true;
+		handle_td_object(*update);
+	}
+	return changed;
+}
+
+void App::handle_td_object(const json& object) {
+	const std::string type = safe_string(object, "@type");
+	if (type == "updateAuthorizationState") {
+		authorization_state_ = object.value("authorization_state", json::object());
+		handle_authorization_state();
+		return;
+	}
+	if (type == "updateConnectionState") {
+		status_line_ = "Connection: " + safe_string(object.at("state"), "@type");
+		return;
+	}
+	if (type == "updateChatOnlineMemberCount") {
+		ChatInfo& chat = chats_[safe_i64(object, "chat_id")];
+		chat.id = safe_i64(object, "chat_id");
+		chat.online_member_count = safe_i32(object, "online_member_count");
+		chat.has_online_member_count = true;
+		return;
+	}
+	if (type == "updateUser") {
+		upsert_user(object.value("user", json::object()));
+		return;
+	}
+	if (type == "updateUserStatus") {
+		update_user_status(safe_i64(object, "user_id"), object.value("status", json::object()));
+		return;
+	}
+	if (type == "updateBasicGroup" || type == "basicGroup") {
+		upsert_basic_group(type == "basicGroup" ? object : object.value("basic_group", json::object()));
+		return;
+	}
+	if (type == "updateSupergroup" || type == "supergroup") {
+		upsert_supergroup(type == "supergroup" ? object : object.value("supergroup", json::object()));
+		return;
+	}
+	if (type == "updateNewChat") {
+		upsert_chat(object.value("chat", json::object()));
+		return;
+	}
+	if (type == "updateChatTitle") {
+		ChatInfo& chat = chats_[safe_i64(object, "chat_id")];
+		chat.id = safe_i64(object, "chat_id");
+		chat.title = safe_string(object, "title");
+		resort_chats();
+		return;
+	}
+	if (type == "updateChatPosition") {
+		ChatInfo& chat = chats_[safe_i64(object, "chat_id")];
+		chat.id = safe_i64(object, "chat_id");
+		apply_chat_position(chat, object.value("position", json::object()));
+		resort_chats();
+		return;
+	}
+	if (type == "updateChatLastMessage") {
+		ChatInfo& chat = chats_[safe_i64(object, "chat_id")];
+		chat.id = safe_i64(object, "chat_id");
+		chat.last_message_preview = preview_message(object.value("last_message", json::object()));
+		if (object.contains("positions") && object.at("positions").is_array()) {
+			chat.in_main_list = false;
+			chat.main_order = 0;
+			for (const auto& position : object.at("positions")) {
+				apply_chat_position(chat, position);
+			}
+		}
+		resort_chats();
+		return;
+	}
+	if (type == "updateChatReadInbox") {
+		ChatInfo& chat = chats_[safe_i64(object, "chat_id")];
+		chat.id = safe_i64(object, "chat_id");
+		chat.unread_count = safe_i32(object, "unread_count");
+		chat.last_read_inbox_message_id = safe_i64(object, "last_read_inbox_message_id");
+		return;
+	}
+	if (type == "updateChatReadOutbox") {
+		ChatInfo& chat = chats_[safe_i64(object, "chat_id")];
+		chat.id = safe_i64(object, "chat_id");
+		chat.last_read_outbox_message_id = safe_i64(object, "last_read_outbox_message_id");
+		return;
+	}
+	if (type == "updateNewMessage") {
+		const json message = object.value("message", json::object());
+		const std::int64_t chat_id = safe_i64(message, "chat_id");
+		if (chat_id == open_chat_id_ && message_scroll_ > 0) {
+			++message_scroll_;
+		}
+		const MessageInfo parsed = parse_message(message);
+		append_message(chat_id, parsed);
+		chats_[chat_id].last_message_preview = preview_message(message);
+		if (chat_id == open_chat_id_ && !parsed.is_outgoing) {
+			mark_message_as_read(chat_id, parsed.id);
+		}
+		return;
+	}
+	if (type == "updateMessageContent") {
+		const std::int64_t chat_id = safe_i64(object, "chat_id");
+		const std::int64_t message_id = safe_i64(object, "message_id");
+		auto chat_it = chats_.find(chat_id);
+		if (chat_it == chats_.end()) {
+			return;
+		}
+		for (auto& message : chat_it->second.messages) {
+			if (message.id == message_id) {
+				const json content = object.value("new_content", json::object());
+				message.text = content_to_text(content, true);
+				if (const auto attachment = parse_attachment(content); attachment.has_value()) {
+					message.has_attachment = true;
+					message.attachment = *attachment;
+				} else {
+					message.has_attachment = false;
+				}
+				break;
+			}
+		}
+		return;
+	}
+	if (type == "updateDeleteMessages") {
+		const std::int64_t chat_id = safe_i64(object, "chat_id");
+		auto chat_it = chats_.find(chat_id);
+		if (chat_it == chats_.end()) {
+			return;
+		}
+		std::set<std::int64_t> deleted;
+		for (const auto& id : object.value("message_ids", json::array())) {
+			if (id.is_number_integer()) {
+				deleted.insert(id.get<std::int64_t>());
+			}
+		}
+		std::vector<MessageInfo> kept;
+		kept.reserve(chat_it->second.messages.size());
+		for (const auto& message : chat_it->second.messages) {
+			if (deleted.find(message.id) == deleted.end()) {
+				kept.push_back(message);
+			}
+		}
+		chat_it->second.messages = std::move(kept);
+		return;
+	}
+	if (type == "updateFile") {
+		update_attachment_file(object.value("file", json::object()));
+		return;
+	}
+	if (type == "updateOption" || type == "ok" || type == "userFullInfo" ||
+		type == "updateHavePendingNotifications" || type == "updateUnreadMessageCount" ||
+		type == "updateUnreadChatCount") {
+		return;
+	}
+	if (type == "error") {
+		const std::string extra = safe_string(object, "@extra");
+		const std::string message = safe_string(object, "message");
+		if (extra.rfind("history:", 0) == 0) {
+			const auto chat_id = static_cast<std::int64_t>(std::stoll(extra.substr(8)));
+			chats_[chat_id].history_loading = false;
+			status_line_ = "History unavailable: " + message;
+			return;
+		}
+		status_line_ = "TDLib error: " + message;
+		return;
+	}
+	if (type == "user") {
+		upsert_user(object);
+		return;
+	}
+	if (type == "chat") {
+		upsert_chat(object);
+		return;
+	}
+	if (type == "chats") {
+		const std::string extra = safe_string(object, "@extra");
+		if (extra == "main_chats") {
+			sync_chat_ids_from_response(object);
+		}
+		return;
+	}
+	if (type == "messages") {
+		const std::string extra = safe_string(object, "@extra");
+		if (extra.rfind("history:", 0) == 0) {
+			const auto chat_id = static_cast<std::int64_t>(std::stoll(extra.substr(8)));
+			merge_history(chat_id, object.value("messages", json::array()));
+		}
+		return;
+	}
+	if (type == "updateMessageSendSucceeded") {
+		const json message = object.value("message", json::object());
+		const std::int64_t chat_id = safe_i64(message, "chat_id");
+		remove_message(chat_id, safe_i64(object, "old_message_id"));
+		append_message(chat_id, parse_message(message));
+		chats_[chat_id].last_message_preview = preview_message(message);
+		status_line_ = "Message sent.";
+		return;
+	}
+
+	const std::string extra = safe_string(object, "@extra");
+	if (extra == "getMe" && object.is_object()) {
+		my_user_id_ = safe_i64(object, "id");
+	}
+}
+
+void App::request_more_chats() {
+	td_.send({
+		{"@type", "getChats"},
+		{"chat_list", {{"@type", "chatListMain"}}},
+		{"limit", kChatPageSize},
+		{"@extra", "main_chats"},
+	});
+	status_line_ = "Loading chats...";
+}
+
+bool App::request_chat_history(std::int64_t chat_id, bool force) {
+	ChatInfo& chat = chats_[chat_id];
+	chat.id = chat_id;
+	if (chat.history_loading && !force) {
+		return false;
+	}
+	chat.history_loading = true;
+	td_.send({
+		{"@type", "getChatHistory"},
+		{"chat_id", chat_id},
+		{"from_message_id", 0},
+		{"offset", 0},
+		{"limit", kHistoryBatchSize},
+		{"only_local", false},
+		{"@extra", "history:" + std::to_string(chat_id)},
+	});
+	return true;
+}
+
+bool App::request_open_chat_history(bool force) {
+	const auto chat_id = open_chat_id();
+	if (!chat_id.has_value()) {
+		return false;
+	}
+	request_chat_details(*chat_id);
+	const bool requested = request_chat_history(*chat_id, force);
+	if (requested) {
+		status_line_ = force ? "Reloading chat history..." : "Loading chat history...";
+	}
+	return requested;
+}
+
+void App::mark_chat_messages_as_read(std::int64_t chat_id) {
+	auto chat_it = chats_.find(chat_id);
+	if (chat_it == chats_.end()) {
+		return;
+	}
+
+	std::vector<std::int64_t> unread_message_ids;
+	unread_message_ids.reserve(chat_it->second.messages.size());
+	for (const auto& message : chat_it->second.messages) {
+		if (message.is_outgoing || message.id == 0) {
+			continue;
+		}
+		if (message.id <= chat_it->second.last_read_inbox_message_id) {
+			continue;
+		}
+		unread_message_ids.push_back(message.id);
+	}
+
+	if (!unread_message_ids.empty()) {
+		td_.send({
+			{"@type", "viewMessages"},
+			{"chat_id", chat_id},
+			{"message_ids", unread_message_ids},
+			{"source", {{"@type", "messageSourceChatHistory"}}},
+			{"force_read", true},
+		});
+	}
+
+	td_.send({
+		{"@type", "toggleChatIsMarkedAsUnread"},
+		{"chat_id", chat_id},
+		{"is_marked_as_unread", false},
+	});
+}
+
+void App::mark_message_as_read(std::int64_t chat_id, std::int64_t message_id) {
+	if (chat_id == 0 || message_id == 0) {
+		return;
+	}
+
+	td_.send({
+		{"@type", "viewMessages"},
+		{"chat_id", chat_id},
+		{"message_ids", json::array({message_id})},
+		{"source", {{"@type", "messageSourceChatHistory"}}},
+		{"force_read", true},
+	});
+}
+
+void App::set_open_chat(std::int64_t chat_id) {
+	if (chat_id == 0) {
+		return;
+	}
+
+	const bool changed_chat = open_chat_id_ != chat_id;
+	ChatInfo& chat = chats_[chat_id];
+	chat.id = chat_id;
+	if (tdlib_open_chat_id_ != 0 && tdlib_open_chat_id_ != chat_id) {
+		td_.send({
+			{"@type", "closeChat"},
+			{"chat_id", tdlib_open_chat_id_},
+		});
+	}
+
+	open_chat_id_ = chat_id;
+	message_scroll_ = 0;
+
+	if (tdlib_open_chat_id_ != chat_id) {
+		td_.send({
+			{"@type", "openChat"},
+			{"chat_id", chat_id},
+		});
+		tdlib_open_chat_id_ = chat_id;
+	}
+
+	mark_chat_messages_as_read(chat_id);
+
+	if (changed_chat) {
+		request_chat_details(chat_id);
+		const bool should_request_history =
+			auto_reload_chat_history_ || !chat.history_loaded || chat.messages.empty();
+		const bool requested = should_request_history &&
+			request_chat_history(chat_id, auto_reload_chat_history_);
+		if (requested) {
+			status_line_ = auto_reload_chat_history_ && chat.history_loaded
+				? "Reloading chat history..."
+				: "Loading chat history...";
+		}
+	}
+}
+
+void App::sync_chat_ids_from_response(const json& response) {
+	if (!response.contains("chat_ids") || !response.at("chat_ids").is_array()) {
+		status_line_ = "Chat list response missing chat ids.";
+		return;
+	}
+
+	std::vector<std::int64_t> chat_ids;
+	for (const auto& entry : response.at("chat_ids")) {
+		if (!entry.is_number_integer()) {
+			continue;
+		}
+		const auto chat_id = entry.get<std::int64_t>();
+		chat_ids.push_back(chat_id);
+		if (chats_.find(chat_id) == chats_.end()) {
+			td_.send({
+				{"@type", "getChat"},
+				{"chat_id", chat_id},
+			});
+		}
+	}
+
+	if (!chat_ids.empty()) {
+		sorted_chat_ids_ = std::move(chat_ids);
+		if (selected_chat_index_ >= static_cast<int>(sorted_chat_ids_.size())) {
+			selected_chat_index_ = std::max(0, static_cast<int>(sorted_chat_ids_.size()) - 1);
+		}
+		if (!open_chat_id().has_value()) {
+			const auto chat_id = highlighted_chat_id();
+			if (chat_id.has_value()) {
+				set_open_chat(*chat_id);
+			}
+		}
+		request_open_chat_history(false);
+		status_line_ = "Chats loaded.";
+		return;
+	}
+
+	status_line_ = "No chats loaded.";
+}
+
+void App::append_message(std::int64_t chat_id, MessageInfo message) {
+	ChatInfo& chat = chats_[chat_id];
+	chat.id = chat_id;
+	auto existing = std::find_if(chat.messages.begin(), chat.messages.end(),
+		[&](const MessageInfo& item) { return item.id == message.id; });
+	if (existing != chat.messages.end()) {
+		*existing = std::move(message);
+	} else {
+		chat.messages.push_back(std::move(message));
+	}
+
+	std::sort(chat.messages.begin(), chat.messages.end(),
+		[](const MessageInfo& lhs, const MessageInfo& rhs) {
+			if (lhs.date != rhs.date) {
+				return lhs.date < rhs.date;
+			}
+			return lhs.id < rhs.id;
+		});
+
+	if (kMaxMessagesPerChat > 0 && chat.messages.size() > kMaxMessagesPerChat) {
+		chat.messages.erase(
+			chat.messages.begin(),
+			chat.messages.begin() +
+				static_cast<std::ptrdiff_t>(chat.messages.size() - kMaxMessagesPerChat));
+	}
+}
+
+void App::remove_message(std::int64_t chat_id, std::int64_t message_id) {
+	if (message_id == 0) {
+		return;
+	}
+
+	auto chat_it = chats_.find(chat_id);
+	if (chat_it == chats_.end()) {
+		return;
+	}
+
+	auto& messages = chat_it->second.messages;
+	messages.erase(
+		std::remove_if(
+			messages.begin(),
+			messages.end(),
+			[&](const MessageInfo& item) { return item.id == message_id; }),
+		messages.end());
+}
+
+void App::merge_history(std::int64_t chat_id, const json& messages) {
+	ChatInfo& chat = chats_[chat_id];
+	chat.history_loading = false;
+	chat.history_loaded = true;
+	for (const auto& message : messages) {
+		append_message(chat_id, parse_message(message));
+	}
+	if (chat_id == open_chat_id_) {
+		mark_chat_messages_as_read(chat_id);
+	}
+	status_line_ = "History loaded.";
+}
+
+void App::update_attachment_file(const json& file) {
+	const std::int32_t file_id = safe_i32(file, "id");
+	if (file_id == 0) {
+		return;
+	}
+
+	const std::int64_t size_bytes = std::max(safe_i64(file, "size"), safe_i64(file, "expected_size"));
+	const json local = file.value("local", json::object());
+	const std::string local_path = safe_string(local, "path");
+	const std::int64_t downloaded_size = safe_i64(local, "downloaded_size");
+	const bool is_downloading_active = local.value("is_downloading_active", false);
+	const bool is_downloaded = local.value("is_downloading_completed", false);
+	const bool can_be_downloaded = local.value("can_be_downloaded", false);
+	const bool can_be_deleted = local.value("can_be_deleted", false);
+
+	for (auto& [chat_id, chat] : chats_) {
+		(void) chat_id;
+		for (auto& message : chat.messages) {
+			if (!message.has_attachment || message.attachment.file_id != file_id) {
+				continue;
+			}
+			if (size_bytes > 0) {
+				message.attachment.size_bytes = size_bytes;
+			}
+			message.attachment.downloaded_size = downloaded_size;
+			message.attachment.local_path = local_path;
+			message.attachment.is_downloading_active = is_downloading_active;
+			message.attachment.is_downloaded = is_downloaded;
+			message.attachment.can_be_downloaded = can_be_downloaded;
+			message.attachment.can_be_deleted = can_be_deleted;
+		}
+	}
+
+	if (pending_attachment_open_.has_value() && pending_attachment_open_->file_id == file_id) {
+		pending_attachment_open_->size_bytes = size_bytes > 0 ? size_bytes : pending_attachment_open_->size_bytes;
+		pending_attachment_open_->downloaded_size = downloaded_size;
+		pending_attachment_open_->local_path = local_path;
+		pending_attachment_open_->is_downloading_active = is_downloading_active;
+		pending_attachment_open_->is_downloaded = is_downloaded;
+		pending_attachment_open_->can_be_downloaded = can_be_downloaded;
+		pending_attachment_open_->can_be_deleted = can_be_deleted;
+		if (!is_downloaded && is_downloading_active) {
+			status_line_ = "Downloading attachment to open " +
+				format_download_progress(
+					pending_attachment_open_->downloaded_size,
+					pending_attachment_open_->size_bytes,
+					pending_attachment_open_->is_downloaded);
+		}
+		if (is_downloaded && !local_path.empty()) {
+			open_attachment(*pending_attachment_open_);
+			pending_attachment_open_.reset();
+		}
+	}
+
+	if (pending_attachment_download_.has_value() && pending_attachment_download_->file_id == file_id) {
+		pending_attachment_download_->size_bytes =
+			size_bytes > 0 ? size_bytes : pending_attachment_download_->size_bytes;
+		pending_attachment_download_->downloaded_size = downloaded_size;
+		pending_attachment_download_->local_path = local_path;
+		pending_attachment_download_->is_downloading_active = is_downloading_active;
+		pending_attachment_download_->is_downloaded = is_downloaded;
+		pending_attachment_download_->can_be_downloaded = can_be_downloaded;
+		pending_attachment_download_->can_be_deleted = can_be_deleted;
+		if (!is_downloaded && is_downloading_active) {
+			status_line_ = "Downloading attachment to ~/Downloads " +
+				format_download_progress(
+					pending_attachment_download_->downloaded_size,
+					pending_attachment_download_->size_bytes,
+					pending_attachment_download_->is_downloaded);
+		}
+		if (is_downloaded && !local_path.empty()) {
+			export_attachment_to_downloads(*pending_attachment_download_);
+			pending_attachment_download_.reset();
+		}
+	}
+}
+
+}  // namespace telegram_tui

src/json.h

@@ -0,0 +1,9 @@
+#pragma once
+
+#include <nlohmann/json.hpp>
+
+namespace telegram_tui {
+
+using json = nlohmann::json;
+
+}  // namespace telegram_tui

src/main.cpp

@@ -0,0 +1,17 @@
+#include <cstdio>
+#include <exception>
+
+#include <curses.h>
+
+#include "app.h"
+
+int main() {
+	try {
+		telegram_tui::App app;
+		return app.run();
+	} catch (const std::exception& error) {
+		endwin();
+		std::fprintf(stderr, "fatal: %s\n", error.what());
+		return 1;
+	}
+}

src/models.cpp

@@ -0,0 +1,25 @@
+#include "models.h"
+
+namespace telegram_tui {
+
+std::string UserInfo::display_name() const {
+	std::string name;
+	if (!first_name.empty()) {
+		name += first_name;
+	}
+	if (!last_name.empty()) {
+		if (!name.empty()) {
+			name += " ";
+		}
+		name += last_name;
+	}
+	if (!name.empty()) {
+		return name;
+	}
+	if (!username.empty()) {
+		return "@" + username;
+	}
+	return "Unknown";
+}
+
+}  // namespace telegram_tui

src/models.h

@@ -0,0 +1,101 @@
+#pragma once
+
+#include <cstdint>
+#include <string>
+#include <vector>
+
+namespace telegram_tui {
+
+constexpr std::size_t kMaxMessagesPerChat = 0;
+constexpr int kPollTimeoutMs = 50;
+constexpr int kChatPageSize = 100;
+constexpr int kHistoryBatchSize = 50;
+
+struct UserInfo {
+	std::int64_t id = 0;
+	std::string first_name;
+	std::string last_name;
+	std::string username;
+	std::string status;
+
+	[[nodiscard]] std::string display_name() const;
+};
+
+enum class AttachmentType {
+	Photo,
+	Video,
+	Document,
+	Audio,
+	Voice,
+	Animation,
+	Sticker,
+};
+
+struct AttachmentInfo {
+	AttachmentType type = AttachmentType::Photo;
+	std::string name;
+	std::int64_t size_bytes = 0;
+	std::int64_t downloaded_size = 0;
+	std::int32_t file_id = 0;
+	std::string local_path;
+	bool is_downloading_active = false;
+	bool can_be_downloaded = false;
+	bool can_be_deleted = false;
+	bool is_downloaded = false;
+};
+
+struct MessageInfo {
+	std::int64_t id = 0;
+	std::int32_t date = 0;
+	bool is_outgoing = false;
+	std::int64_t reply_to_message_id = 0;
+	bool has_attachment = false;
+	AttachmentInfo attachment;
+	std::string forward_info;
+	std::string sender;
+	std::string text;
+	std::string via_bot;
+};
+
+struct ChatInfo {
+	std::int64_t id = 0;
+	std::int64_t private_user_id = 0;
+	std::int64_t basic_group_id = 0;
+	std::int64_t supergroup_id = 0;
+	std::int64_t last_read_inbox_message_id = 0;
+	std::int64_t last_read_outbox_message_id = 0;
+	std::string title = "Loading...";
+	std::string username;
+	std::string last_message_preview;
+	std::int32_t unread_count = 0;
+	std::int32_t member_count = 0;
+	std::int32_t online_member_count = 0;
+	std::int64_t main_order = 0;
+	bool is_channel = false;
+	bool in_main_list = false;
+	bool history_loading = false;
+	bool history_loaded = false;
+	bool details_requested = false;
+	bool has_member_count = false;
+	bool has_online_member_count = false;
+	std::vector<MessageInfo> messages;
+};
+
+enum class FocusPane {
+	Chats,
+	Messages,
+};
+
+enum class InputMode {
+	None,
+	Compose,
+	ApiId,
+	ApiHash,
+	PhoneNumber,
+	AuthCode,
+	Password,
+	FirstName,
+	LastName,
+};
+
+}  // namespace telegram_tui

src/td_client.cpp

@@ -0,0 +1,66 @@
+#include "td_client.h"
+
+#include <string>
+
+#include <td/telegram/td_json_client.h>
+
+namespace telegram_tui {
+
+namespace {
+
+void configure_tdlib_logging() {
+	const char* stream_request =
+		R"({"@type":"setLogStream","log_stream":{"@type":"logStreamEmpty"}})";
+	const char* verbosity_request =
+		R"({"@type":"setLogVerbosityLevel","new_verbosity_level":0})";
+
+	td_json_client_execute(nullptr, stream_request);
+	td_json_client_execute(nullptr, verbosity_request);
+}
+
+}  // namespace
+
+TdClient::TdClient() {
+	configure_tdlib_logging();
+	client_ = td_json_client_create();
+}
+
+TdClient::~TdClient() {
+	if (client_ != nullptr) {
+		td_json_client_destroy(client_);
+	}
+}
+
+void TdClient::send(const json& request) {
+	const std::string payload = request.dump();
+	td_json_client_send(client_, payload.c_str());
+}
+
+std::optional<json> TdClient::execute(const json& request) {
+	const std::string payload = request.dump();
+	const char* raw = td_json_client_execute(client_, payload.c_str());
+	if (raw == nullptr) {
+		return std::nullopt;
+	}
+
+	try {
+		return json::parse(raw);
+	} catch (...) {
+		return std::nullopt;
+	}
+}
+
+std::optional<json> TdClient::receive(double timeout_seconds) {
+	const char* raw = td_json_client_receive(client_, timeout_seconds);
+	if (raw == nullptr) {
+		return std::nullopt;
+	}
+
+	try {
+		return json::parse(raw);
+	} catch (...) {
+		return std::nullopt;
+	}
+}
+
+}  // namespace telegram_tui

src/td_client.h

@@ -0,0 +1,25 @@
+#pragma once
+
+#include <optional>
+
+#include "json.h"
+
+namespace telegram_tui {
+
+class TdClient {
+  public:
+	TdClient();
+	~TdClient();
+
+	TdClient(const TdClient&) = delete;
+	TdClient& operator=(const TdClient&) = delete;
+
+	void send(const json& request);
+	[[nodiscard]] std::optional<json> execute(const json& request);
+	[[nodiscard]] std::optional<json> receive(double timeout_seconds);
+
+  private:
+	void* client_ = nullptr;
+};
+
+}  // namespace telegram_tui

src/util.cpp

@@ -0,0 +1,366 @@
+#include "util.h"
+
+#include <algorithm>
+#include <cctype>
+#include <cstdint>
+#include <cstdlib>
+#include <ctime>
+#include <fstream>
+#include <sstream>
+#include <wchar.h>
+
+namespace telegram_tui {
+
+namespace {
+
+std::size_t utf8_sequence_size(unsigned char lead) {
+	if ((lead & 0x80U) == 0) {
+		return 1;
+	}
+	if ((lead & 0xE0U) == 0xC0U) {
+		return 2;
+	}
+	if ((lead & 0xF0U) == 0xE0U) {
+		return 3;
+	}
+	if ((lead & 0xF8U) == 0xF0U) {
+		return 4;
+	}
+	return 1;
+}
+
+bool is_utf8_continuation(unsigned char ch) {
+	return (ch & 0xC0U) == 0x80U;
+}
+
+std::uint32_t decode_utf8_codepoint(const std::string& text, std::size_t offset, std::size_t* size_out = nullptr) {
+	if (offset >= text.size()) {
+		if (size_out != nullptr) {
+			*size_out = 0;
+		}
+		return 0;
+	}
+
+	const auto lead = static_cast<unsigned char>(text[offset]);
+	std::size_t size = utf8_sequence_size(lead);
+	if (offset + size > text.size()) {
+		size = 1;
+	}
+	for (std::size_t i = 1; i < size; ++i) {
+		if (!is_utf8_continuation(static_cast<unsigned char>(text[offset + i]))) {
+			size = 1;
+			break;
+		}
+	}
+
+	if (size_out != nullptr) {
+		*size_out = size;
+	}
+
+	if (size == 1) {
+		return lead;
+	}
+	if (size == 2) {
+		return ((lead & 0x1FU) << 6) |
+			(static_cast<unsigned char>(text[offset + 1]) & 0x3FU);
+	}
+	if (size == 3) {
+		return ((lead & 0x0FU) << 12) |
+			((static_cast<unsigned char>(text[offset + 1]) & 0x3FU) << 6) |
+			(static_cast<unsigned char>(text[offset + 2]) & 0x3FU);
+	}
+	return ((lead & 0x07U) << 18) |
+		((static_cast<unsigned char>(text[offset + 1]) & 0x3FU) << 12) |
+		((static_cast<unsigned char>(text[offset + 2]) & 0x3FU) << 6) |
+		(static_cast<unsigned char>(text[offset + 3]) & 0x3FU);
+}
+
+}  // namespace
+
+std::string get_env(const char* name) {
+	const char* value = std::getenv(name);
+	return value == nullptr ? std::string() : std::string(value);
+}
+
+std::string trim_copy(std::string value) {
+	auto not_space = [](unsigned char c) { return !std::isspace(c); };
+	while (!value.empty() && !not_space(static_cast<unsigned char>(value.front()))) {
+		value.erase(value.begin());
+	}
+	while (!value.empty() && !not_space(static_cast<unsigned char>(value.back()))) {
+		value.pop_back();
+	}
+	return value;
+}
+
+std::string single_line(std::string text) {
+	for (char& c : text) {
+		if (c == '\n' || c == '\r' || c == '\t') {
+			c = ' ';
+		}
+	}
+	return trim_copy(std::move(text));
+}
+
+bool is_decimal_number(const std::string& value) {
+	return !value.empty() &&
+		std::all_of(value.begin(), value.end(), [](unsigned char ch) { return std::isdigit(ch); });
+}
+
+std::filesystem::path data_root() {
+	if (const char* xdg = std::getenv("XDG_DATA_HOME"); xdg != nullptr && *xdg != '\0') {
+		return std::filesystem::path(xdg) / "telegram-tui";
+	}
+	if (const char* home = std::getenv("HOME"); home != nullptr && *home != '\0') {
+		return std::filesystem::path(home) / ".local" / "share" / "telegram-tui";
+	}
+	return std::filesystem::current_path() / ".telegram-tui-data";
+}
+
+StoredConfig load_app_config() {
+	const std::filesystem::path path = data_root() / "config.json";
+	std::ifstream input(path);
+	if (!input.is_open()) {
+		return {};
+	}
+
+	try {
+		const json config = json::parse(input, nullptr, true, true);
+		if (!config.is_object()) {
+			return {};
+		}
+		return StoredConfig{
+			safe_string(config, "api_id"),
+			safe_string(config, "api_hash"),
+			config.value("auto_reload_chat_history", false),
+		};
+	} catch (const json::exception&) {
+		return {};
+	}
+}
+
+bool save_app_config(const StoredConfig& config) {
+	const std::filesystem::path path = data_root() / "config.json";
+	try {
+		if (path.has_parent_path()) {
+			std::filesystem::create_directories(path.parent_path());
+		}
+
+		json document = json::object();
+		if (!config.api_id.empty()) {
+			document["api_id"] = config.api_id;
+		}
+		if (!config.api_hash.empty()) {
+			document["api_hash"] = config.api_hash;
+		}
+		document["auto_reload_chat_history"] = config.auto_reload_chat_history;
+
+		std::ofstream output(path, std::ios::trunc);
+		if (!output.is_open()) {
+			return false;
+		}
+		output << document.dump(2) << '\n';
+		return static_cast<bool>(output);
+	} catch (const std::exception&) {
+		return false;
+	}
+}
+
+std::string safe_string(const json& object, const char* key) {
+	if (!object.contains(key) || !object.at(key).is_string()) {
+		return {};
+	}
+	return object.at(key).get<std::string>();
+}
+
+std::int64_t safe_i64(const json& object, const char* key) {
+	if (!object.contains(key) || !object.at(key).is_number_integer()) {
+		return 0;
+	}
+	return object.at(key).get<std::int64_t>();
+}
+
+std::int32_t safe_i32(const json& object, const char* key) {
+	if (!object.contains(key) || !object.at(key).is_number_integer()) {
+		return 0;
+	}
+	return object.at(key).get<std::int32_t>();
+}
+
+std::string format_time(std::int32_t unix_time) {
+	if (unix_time <= 0) {
+		return "--:--";
+	}
+
+	std::time_t raw = unix_time;
+	std::tm tm = *std::localtime(&raw);
+	char buffer[16] = {};
+	std::strftime(buffer, sizeof(buffer), "%H:%M", &tm);
+	return buffer;
+}
+
+std::string format_date(std::int32_t unix_time) {
+	if (unix_time <= 0) {
+		return "Unknown day";
+	}
+
+	std::time_t raw = unix_time;
+	std::tm tm = *std::localtime(&raw);
+	char buffer[32] = {};
+	std::strftime(buffer, sizeof(buffer), "%Y-%m-%d", &tm);
+	return buffer;
+}
+
+std::string format_datetime(std::int32_t unix_time) {
+	if (unix_time <= 0) {
+		return "Unknown time";
+	}
+
+	std::time_t raw = unix_time;
+	std::tm tm = *std::localtime(&raw);
+	char buffer[32] = {};
+	std::strftime(buffer, sizeof(buffer), "%Y-%m-%d %H:%M", &tm);
+	return buffer;
+}
+
+std::string format_file_size(std::int64_t size_bytes) {
+	if (size_bytes <= 0) {
+		return "?";
+	}
+
+	static constexpr const char* units[] = {"B", "KB", "MB", "GB", "TB"};
+	double size = static_cast<double>(size_bytes);
+	std::size_t unit_index = 0;
+	while (size >= 1024.0 && unit_index + 1 < std::size(units)) {
+		size /= 1024.0;
+		++unit_index;
+	}
+
+	std::ostringstream stream;
+	stream.setf(std::ios::fixed);
+	stream.precision(unit_index == 0 ? 0 : 1);
+	stream << size << ' ' << units[unit_index];
+	return stream.str();
+}
+
+std::vector<std::string> wrap_text(const std::string& text, int width) {
+	if (width <= 1) {
+		return {text};
+	}
+
+	std::vector<std::string> lines;
+	std::stringstream stream(text);
+	std::string paragraph;
+	while (std::getline(stream, paragraph, '\n')) {
+		paragraph = single_line(std::move(paragraph));
+		if (paragraph.empty()) {
+			lines.emplace_back();
+			continue;
+		}
+
+		std::stringstream words(paragraph);
+		std::string word;
+		std::string current;
+		while (words >> word) {
+			if (current.empty()) {
+				current = word;
+				continue;
+			}
+
+			if (static_cast<int>(current.size() + 1 + word.size()) > width) {
+				lines.push_back(current);
+				current = word;
+			} else {
+				current += " ";
+				current += word;
+			}
+		}
+		if (!current.empty()) {
+			lines.push_back(current);
+		}
+	}
+
+	if (lines.empty()) {
+		lines.emplace_back();
+	}
+	return lines;
+}
+
+std::size_t utf8_byte_index_from_utf16_offset(const std::string& text, std::size_t utf16_offset) {
+	std::size_t byte_index = 0;
+	std::size_t utf16_units = 0;
+	while (byte_index < text.size() && utf16_units < utf16_offset) {
+		std::size_t size = 0;
+		const std::uint32_t codepoint = decode_utf8_codepoint(text, byte_index, &size);
+		if (size == 0) {
+			break;
+		}
+		const std::size_t units = codepoint > 0xFFFFU ? 2 : 1;
+		if (utf16_units + units > utf16_offset) {
+			break;
+		}
+		utf16_units += units;
+		byte_index += size;
+	}
+	return byte_index;
+}
+
+std::size_t utf8_prev_index(const std::string& text, std::size_t byte_index) {
+	if (byte_index == 0 || text.empty()) {
+		return 0;
+	}
+
+	std::size_t index = std::min(byte_index, text.size()) - 1;
+	while (index > 0 && is_utf8_continuation(static_cast<unsigned char>(text[index]))) {
+		--index;
+	}
+	return index;
+}
+
+std::size_t utf8_next_index(const std::string& text, std::size_t byte_index) {
+	if (byte_index >= text.size()) {
+		return text.size();
+	}
+
+	std::size_t size = 0;
+	decode_utf8_codepoint(text, byte_index, &size);
+	return std::min(text.size(), byte_index + std::max<std::size_t>(1, size));
+}
+
+int utf8_display_width(const std::string& text, std::size_t byte_limit) {
+	const std::size_t limit = std::min(byte_limit, text.size());
+	int width = 0;
+	std::size_t index = 0;
+	while (index < limit) {
+		std::size_t size = 0;
+		const std::uint32_t codepoint = decode_utf8_codepoint(text, index, &size);
+		if (size == 0) {
+			break;
+		}
+
+		int char_width = 1;
+		if (codepoint <= static_cast<std::uint32_t>(WCHAR_MAX)) {
+			const int measured = ::wcwidth(static_cast<wchar_t>(codepoint));
+			if (measured > 0) {
+				char_width = measured;
+			}
+		}
+		width += char_width;
+		index += size;
+	}
+	return width;
+}
+
+void pop_utf8_back(std::string& text) {
+	if (text.empty()) {
+		return;
+	}
+
+	std::size_t start = text.size() - 1;
+	while (start > 0 && is_utf8_continuation(static_cast<unsigned char>(text[start]))) {
+		--start;
+	}
+	text.erase(start);
+}
+
+}  // namespace telegram_tui

src/util.h

@@ -0,0 +1,39 @@
+#pragma once
+
+#include <cstdint>
+#include <filesystem>
+#include <string>
+#include <vector>
+
+#include "json.h"
+
+namespace telegram_tui {
+
+struct StoredConfig {
+	std::string api_id;
+	std::string api_hash;
+	bool auto_reload_chat_history = false;
+};
+
+[[nodiscard]] std::string get_env(const char* name);
+[[nodiscard]] std::string trim_copy(std::string value);
+[[nodiscard]] std::string single_line(std::string text);
+[[nodiscard]] bool is_decimal_number(const std::string& value);
+[[nodiscard]] std::filesystem::path data_root();
+[[nodiscard]] StoredConfig load_app_config();
+bool save_app_config(const StoredConfig& config);
+[[nodiscard]] std::string safe_string(const json& object, const char* key);
+[[nodiscard]] std::int64_t safe_i64(const json& object, const char* key);
+[[nodiscard]] std::int32_t safe_i32(const json& object, const char* key);
+[[nodiscard]] std::string format_time(std::int32_t unix_time);
+[[nodiscard]] std::string format_date(std::int32_t unix_time);
+[[nodiscard]] std::string format_datetime(std::int32_t unix_time);
+[[nodiscard]] std::string format_file_size(std::int64_t size_bytes);
+[[nodiscard]] std::vector<std::string> wrap_text(const std::string& text, int width);
+[[nodiscard]] std::size_t utf8_byte_index_from_utf16_offset(const std::string& text, std::size_t utf16_offset);
+[[nodiscard]] std::size_t utf8_prev_index(const std::string& text, std::size_t byte_index);
+[[nodiscard]] std::size_t utf8_next_index(const std::string& text, std::size_t byte_index);
+[[nodiscard]] int utf8_display_width(const std::string& text, std::size_t byte_limit = std::string::npos);
+void pop_utf8_back(std::string& text);
+
+}  // namespace telegram_tui