// Oak Video Editor - Non-Linear Video Editor
// Copyright (C) 2026 Oak Team
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

//! Tiny localization layer: embedded en-US / zh-CN string tables, a
//! [`tr`] lookup used by every user-visible label in the app, and a runtime
//! language setting persisted through the oakengine config C ABI
//! (`oakengine_config_get_string` / `oakengine_config_set_string`, the
//! process-wide `ConfigStore`).
//!
//! # The tables
//!
//! Plain key → string arrays (no serde, no build step). [`tr`] falls back
//! from the active language to en-US and then to the key itself, so a
//! missing key can never panic — it degrades to a visible-but-identifiable
//! key string instead.
//!
//! # The language setting
//!
//! The language is a process-global [`Language`] (an atomic, so any thread
//! can read it without locking). At startup [`init`] loads the persisted
//! value from the config key `Language` (`"zh-CN"` / `"en-US"`; empty or
//! unknown values mean en-US). [`set_language`] flips the global and writes
//! the new value back through the same key so the preference survives
//! restarts. The preferences dialog drives the same setting through the
//! config C ABI directly.

use std::sync::atomic::{AtomicU8, Ordering};

/// The languages shipped with the app.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Language {
	/// English (United States).
	EnUs,
	/// Simplified Chinese.
	ZhCN,
}

impl Language {
	/// The stable config/table code, e.g. `"en-US"`.
	pub fn code(self) -> &'static str {
		match self {
			Language::EnUs => "en-US",
			Language::ZhCN => "zh-CN",
		}
	}

	/// Parses a stored config value into a language. Empty or unknown values
	/// fall back to en-US.
	fn from_code(code: &str) -> Self {
		let code = code.trim().to_ascii_lowercase();
		if code.starts_with("zh") {
			Language::ZhCN
		} else {
			Language::EnUs
		}
	}
}

/// The current language, as an atomic tag (0 = en-US, 1 = zh-CN).
static CURRENT: AtomicU8 = AtomicU8::new(0);

/// The active language.
pub fn language() -> Language {
	match CURRENT.load(Ordering::Relaxed) {
		1 => Language::ZhCN,
		_ => Language::EnUs,
	}
}

/// Switches the active language live and persists the choice through the
/// oakengine config C ABI.
pub fn set_language(language: Language) {
	CURRENT.store(match language {
		Language::EnUs => 0,
		Language::ZhCN => 1,
	}, Ordering::Relaxed);
	persist_language(language);
	sync_widgets();
}

/// Loads the persisted language from the oakengine config C ABI. Called once
/// at startup. Never fails: a missing key keeps the default (en-US).
pub fn init() {
	let code = crate::oakui::real::config_get_string("Language");
	if !code.is_empty() {
		set_language(Language::from_code(&code));
	} else {
		sync_widgets();
	}
}

/// Writes `language` back to the config `Language` key through the facade
/// config C ABI.
fn persist_language(language: Language) {
	crate::oakui::real::config_set_string("Language", language.code());
}

/// Translates `key` in the active language.
///
/// Never panics: unknown keys fall back to en-US and then to the key itself,
/// so a typo'd key is visible in the UI instead of crashing it.
pub fn tr(key: &'static str) -> &'static str {
	match language() {
		Language::EnUs => en(key),
		Language::ZhCN => zh(key).unwrap_or_else(|| en(key)),
	}
}

/// The keys the gpui widget crates localize through
/// `gpui_widgets::i18n` (viewer transport labels, effect-stack empty state).
pub const WIDGET_KEYS: &[&str] = &[
	"viewer.safe_frames",
	"viewer.zoom",
	"viewer.no_frame_source",
	"viewer.in_point",
	"viewer.step_back",
	"viewer.play",
	"viewer.pause",
	"viewer.step_forward",
	"viewer.out_point",
	"viewer.clear_range",
	"effect_stack.empty",
	"effect_stack.add",
];

/// Installs the active language's widget strings into the
/// `gpui_widgets::i18n` string-table hook, so the widget-baked labels follow
/// the app language on the next render. Called on startup and on every
/// language switch; the widgets keep their built-in defaults otherwise.
pub fn sync_widgets() {
	let mut table = gpui_widgets::i18n::StringTable::new();
	for key in WIDGET_KEYS {
		table.insert((*key).to_string(), tr(key).to_string());
	}
	gpui_widgets::i18n::set_table(table);
}

/// Looks `key` up in the en-US table.
fn en(key: &'static str) -> &'static str {
	EN
		.iter()
		.find(|(k, _)| *k == key)
		.map(|(_, v)| *v)
		.unwrap_or(key)
}

/// Looks `key` up in the zh-CN table.
fn zh(key: &'static str) -> Option<&'static str> {
	ZH
		.iter()
		.find(|(k, _)| *k == key)
		.map(|(_, v)| *v)
}

/// The en-US table. Every key must also exist in [`ZH`]; [`tr`] tolerates
/// missing entries but the tests below enforce parity.
const EN: &[(&str, &str)] = &[
	// --- menu bar titles ---
	("menu.file", "File(F)"),
	("menu.edit", "Edit(E)"),
	("menu.view", "View(V)"),
	("menu.playback", "Playback(P)"),
	("menu.sequence", "Sequence(S)"),
	("menu.window", "Window(W)"),
	("menu.tools", "Tools(T)"),
	("menu.help", "Help(H)"),
	// --- File ---
	("menu.file.new_project", "New Project…"),
	("menu.file.open_project", "Open Project…"),
	("menu.file.save", "Save"),
	("menu.file.save_as", "Save As…"),
	("menu.file.close", "Close Project"),
	("menu.file.export", "Export…"),
	("menu.file.quit", "Quit"),
	// --- Edit ---
	("menu.edit.undo", "Undo"),
	("menu.edit.redo", "Redo"),
	("menu.edit.cut", "Cut"),
	("menu.edit.copy", "Copy"),
	("menu.edit.paste", "Paste"),
	("menu.edit.delete", "Delete"),
	("menu.edit.ripple_delete", "Ripple Delete"),
	// --- View ---
	("menu.view.theme", "Theme"),
	("menu.view.theme.dark", "Olive Dark"),
	("menu.view.theme.light", "Olive Light"),
	("menu.view.language", "Language"),
	("menu.view.language.en", "English"),
	("menu.view.language.zh", "简体中文"),
	("menu.view.preferences", "Preferences…"),
	// --- Playback ---
	("menu.playback.play_pause", "Play/Pause"),
	("menu.playback.prev_frame", "Previous Frame"),
	("menu.playback.next_frame", "Next Frame"),
	("menu.playback.to_start", "Jump to Sequence Start"),
	// --- Sequence ---
	("menu.sequence.add_video_track", "Add Video Track"),
	("menu.sequence.add_audio_track", "Add Audio Track"),
	("menu.sequence.remove_track", "Remove Selected Track"),
	("menu.sequence.split_at_playhead", "Split Clips at Playhead"),
	("menu.sequence.settings", "Sequence Settings…"),
	// --- Window ---
	("menu.window.project", "Project"),
	("menu.window.source_viewer", "Source Viewer"),
	("menu.window.program_viewer", "Program Viewer"),
	("menu.window.node_editor", "Node Editor"),
	("menu.window.inspector", "Inspector"),
	("menu.window.history", "History"),
	("menu.window.timeline", "Timeline"),
	// --- Tools ---
	("menu.tools.select", "Select"),
	("menu.tools.razor", "Razor"),
	("menu.tools.snap", "Snap"),
	// --- Help ---
	("menu.help.about", "About Oak…"),
	// --- dock panel titles ---
	("panel.project", "Project"),
	("panel.source_viewer", "Source Viewer"),
	("panel.program_viewer", "Program Viewer"),
	("panel.node_editor", "Node Editor"),
	("panel.inspector", "Inspector"),
	("panel.history", "History"),
	("panel.timeline", "Timeline"),
	// --- status bar ---
	("status.ready", "Ready"),
	("status.cache", "Cache: Enabled"),
	("status.proxy", "Proxy: Off"),
	("status.autosave", "Autosave: 3 min ago"),
	("status.untitled", "Untitled Project"),
	("status.backend", "Engine:"),
	// --- timeline toolbar ---
	("timeline.tool.select", "Select"),
	("timeline.tool.razor", "Razor"),
	("timeline.tool.ripple", "Ripple"),
	("timeline.tool.slip", "Slip"),
	("timeline.tool.roll", "Roll"),
	("timeline.tool.zoom", "Zoom"),
	("timeline.tool.slide", "Slide"),
	("timeline.tool.track_select", "Track Select"),
	("timeline.zoom", "Zoom"),
	("timeline.zoom_in", "Zoom In"),
	("timeline.zoom_out", "Zoom Out"),
	("timeline.track_height", "Track Height"),
	("timeline.snap", "Snap"),
	// --- project bin ---
	("bin.footage", "Footage"),
	("bin.music", "Music"),
	// --- history (undo stack demo entries) ---
	("history.transform", "Transform"),
	("history.move_clip", "Move Clip"),
	("history.delete_clip", "Delete"),
	("history.add_lut", "Add OCIO LUT"),
	("history.set_in_point", "Set In Point"),
	// --- node editor ---
	("node.fit", "Fit"),
	// --- viewer header chips ---
	("viewer.source", "Source Viewer · Source"),
	("viewer.program", "Program Viewer · Program"),
	// --- program viewer tabs and scope labels ---
	("viewer.picture", "Picture"),
	("viewer.scopes", "Scopes"),
	("scope.histogram", "Histogram"),
	("scope.waveform", "Waveform"),
	("scope.vectorscope", "Vectorscope"),
	// --- viewer transport tooltips ---
	("viewer.in_point", "Set In Point"),
	("viewer.step_back", "Previous Frame"),
	("viewer.play", "Play"),
	("viewer.pause", "Pause"),
	("viewer.step_forward", "Next Frame"),
	("viewer.out_point", "Set Out Point"),
	("viewer.clear_range", "Clear In/Out Range"),
	// --- widget-baked strings (synced to gpui_widgets::i18n) ---
	("viewer.safe_frames", "Safe Frames"),
	("viewer.zoom", "Zoom"),
	("viewer.no_frame_source", "No frame source"),
	("effect_stack.empty", "No selection"),
	("effect_stack.add", "+ Add Effect"),
	// --- inspector ---
	("inspector.params", "Parameters (placeholder)"),
	// --- dialogs ---
	("dialog.cancel", "Cancel"),
	("dialog.close", "Close"),
	("file.open.title", "Open Project"),
	("file.save_as.title", "Save Project As"),
	("preferences.title", "Preferences"),
	("preferences.backend", "Renderer backend"),
	("preferences.backend.placeholder", "Select a backend…"),
	("preferences.language", "Language"),
	("preferences.language.placeholder", "Select a language…"),
	("preferences.hint", "The renderer backend applies to the render worker at the next launch; the language switches immediately."),
	("export.title", "Export Sequence"),
	("export.format", "Format"),
	("export.format.placeholder", "Select a format…"),
	("export.path", "Output path"),
	("export.run", "Export"),
	("export.hint", "The sequence is exported through the oaktask export path; progress is shown in the dialog."),
	("export.progress.title", "Exporting"),
	("export.progress.label", "Rendering frames…"),
];

/// The zh-CN table. Mirrors [`EN`] key-for-key.
const ZH: &[(&str, &str)] = &[
	// --- menu bar titles ---
	("menu.file", "文件(F)"),
	("menu.edit", "编辑(E)"),
	("menu.view", "视图(V)"),
	("menu.playback", "回放(P)"),
	("menu.sequence", "序列(S)"),
	("menu.window", "窗口(W)"),
	("menu.tools", "工具(T)"),
	("menu.help", "帮助(H)"),
	// --- File ---
	("menu.file.new_project", "新建项目…"),
	("menu.file.open_project", "打开项目…"),
	("menu.file.save", "保存"),
	("menu.file.save_as", "另存为…"),
	("menu.file.close", "关闭项目"),
	("menu.file.export", "导出…"),
	("menu.file.quit", "退出"),
	// --- Edit ---
	("menu.edit.undo", "撤销"),
	("menu.edit.redo", "重做"),
	("menu.edit.cut", "剪切"),
	("menu.edit.copy", "复制"),
	("menu.edit.paste", "粘贴"),
	("menu.edit.delete", "删除"),
	("menu.edit.ripple_delete", "波纹删除"),
	// --- View ---
	("menu.view.theme", "主题"),
	("menu.view.theme.dark", "Olive Dark"),
	("menu.view.theme.light", "Olive Light"),
	("menu.view.language", "语言"),
	("menu.view.language.en", "English"),
	("menu.view.language.zh", "简体中文"),
	("menu.view.preferences", "偏好设置…"),
	// --- Playback ---
	("menu.playback.play_pause", "播放/暂停"),
	("menu.playback.prev_frame", "上一帧"),
	("menu.playback.next_frame", "下一帧"),
	("menu.playback.to_start", "跳到序列起点"),
	// --- Sequence ---
	("menu.sequence.add_video_track", "添加视频轨道"),
	("menu.sequence.add_audio_track", "添加音频轨道"),
	("menu.sequence.remove_track", "删除所选轨道"),
	("menu.sequence.split_at_playhead", "在播放头处分割片段"),
	("menu.sequence.settings", "序列设置…"),
	// --- Window ---
	("menu.window.project", "项目"),
	("menu.window.source_viewer", "素材查看器"),
	("menu.window.program_viewer", "序列查看器"),
	("menu.window.node_editor", "节点编辑器"),
	("menu.window.inspector", "检查器"),
	("menu.window.history", "历史记录"),
	("menu.window.timeline", "时间线"),
	// --- Tools ---
	("menu.tools.select", "选择"),
	("menu.tools.razor", "剃刀"),
	("menu.tools.snap", "吸附"),
	// --- Help ---
	("menu.help.about", "关于 Oak…"),
	// --- dock panel titles ---
	("panel.project", "项目"),
	("panel.source_viewer", "素材查看器"),
	("panel.program_viewer", "序列查看器"),
	("panel.node_editor", "节点编辑器"),
	("panel.inspector", "检查器"),
	("panel.history", "历史记录"),
	("panel.timeline", "时间线"),
	// --- status bar ---
	("status.ready", "就绪"),
	("status.cache", "缓存:已启用"),
	("status.proxy", "代理:关"),
	("status.autosave", "自动保存:3分钟前"),
	("status.untitled", "未命名项目"),
	("status.backend", "引擎:"),
	// --- timeline toolbar ---
	("timeline.tool.select", "选择"),
	("timeline.tool.razor", "剃刀"),
	("timeline.tool.ripple", "波纹"),
	("timeline.tool.slip", "滑动"),
	("timeline.tool.roll", "滚动"),
	("timeline.tool.zoom", "缩放"),
	("timeline.tool.slide", "滑移"),
	("timeline.tool.track_select", "轨道选择"),
	("timeline.zoom", "缩放"),
	("timeline.zoom_in", "放大"),
	("timeline.zoom_out", "缩小"),
	("timeline.track_height", "轨道高"),
	("timeline.snap", "吸附"),
	// --- project bin ---
	("bin.footage", "素材"),
	("bin.music", "音乐"),
	// --- history (undo stack demo entries) ---
	("history.transform", "变换"),
	("history.move_clip", "移动片段"),
	("history.delete_clip", "删除"),
	("history.add_lut", "添加 OCIO LUT"),
	("history.set_in_point", "设置入点"),
	// --- node editor ---
	("node.fit", "适配"),
	// --- viewer header chips ---
	("viewer.source", "素材查看器 · 源"),
	("viewer.program", "序列查看器 · 节目"),
	// --- program viewer tabs and scope labels ---
	("viewer.picture", "画面"),
	("viewer.scopes", "示波器"),
	("scope.histogram", "直方图"),
	("scope.waveform", "波形图"),
	("scope.vectorscope", "矢量示波器"),
	// --- viewer transport tooltips ---
	("viewer.in_point", "设置入点"),
	("viewer.step_back", "上一帧"),
	("viewer.play", "播放"),
	("viewer.pause", "暂停"),
	("viewer.step_forward", "下一帧"),
	("viewer.out_point", "设置出点"),
	("viewer.clear_range", "清除入出点"),
	// --- widget-baked strings (synced to gpui_widgets::i18n) ---
	("viewer.safe_frames", "安全框"),
	("viewer.zoom", "缩放"),
	("viewer.no_frame_source", "无帧源"),
	("effect_stack.empty", "未选择"),
	("effect_stack.add", "+ 添加效果"),
	// --- inspector ---
	("inspector.params", "参数（占位）"),
	// --- dialogs ---
	("dialog.cancel", "取消"),
	("dialog.close", "关闭"),
	("file.open.title", "打开项目"),
	("file.save_as.title", "项目另存为"),
	("preferences.title", "偏好设置"),
	("preferences.backend", "渲染后端"),
	("preferences.backend.placeholder", "选择一个后端…"),
	("preferences.language", "语言"),
	("preferences.language.placeholder", "选择语言…"),
	("preferences.hint", "渲染后端在下次启动渲染工作进程时生效；语言立即切换。"),
	("export.title", "导出序列"),
	("export.format", "格式"),
	("export.format.placeholder", "选择格式…"),
	("export.path", "输出路径"),
	("export.run", "导出"),
	("export.hint", "序列通过 oaktask 导出路径导出；进度显示在对话框中。"),
	("export.progress.title", "正在导出"),
	("export.progress.label", "正在渲染帧…"),
];

// ---------------------------------------------------------------------------
// Config persistence
// ---------------------------------------------------------------------------
//
// The language setting round-trips through the oakengine config C ABI
// (`oakengine_config_get_string` / `oakengine_config_set_string`, the
// in-process `ConfigStore` backed by the linked oakcommon crate). See
// [`real`](crate::oakui::real) for the facade-side helpers.

/// Serializes every test that mutates the process-global language, so
/// parallel tests (in this module and in [`crate::app`]) cannot race each
/// other's `set_language` calls.
#[cfg(test)]
pub(crate) fn lang_test_lock() -> &'static std::sync::Mutex<()> {
	static LOCK: std::sync::Mutex<()> = std::sync::Mutex::new(());
	&LOCK
}

#[cfg(test)]
mod tests {
	use super::*;

	fn lang_lock() -> &'static std::sync::Mutex<()> {
		lang_test_lock()
	}

	/// Every key must exist in both tables, with a non-empty translation.
	#[test]
	fn every_key_exists_in_both_languages() {
		assert_eq!(EN.len(), ZH.len(), "tables must have identical key sets");
		for (key, en_value) in EN {
			assert!(!key.is_empty());
			assert!(!en_value.is_empty(), "empty en-US value for {key}");
			let zh_value = ZH
				.iter()
				.find(|(k, _)| *k == *key)
				.unwrap_or_else(|| panic!("zh-CN table is missing key {key}"));
			assert!(
				!zh_value.1.is_empty(),
				"empty zh-CN value for {key}"
			);
		}
	}

	/// No table entry may be its own key, and identical en-US / zh-CN values
	/// are only allowed for proper nouns that stay in their original language
	/// (theme names, language names, codecs) — anything else means one side
	/// was left untranslated.
	#[test]
	fn no_untranslated_values() {
		// Values that are intentionally identical across languages.
		let shared = [
			"Olive Dark",
			"Olive Light",
			"English",
			"简体中文",
			"en-US",
			"zh-CN",
			"OpenGL",
			"Metal",
			"Vulkan",
			"MP4",
		];
		for (key, en_value) in EN {
			assert_ne!(
				*en_value, *key,
				"en-US value for {key} is still the raw key (untranslated)"
			);
			let zh_value = ZH
				.iter()
				.find(|(k, _)| *k == *key)
				.map(|(_, v)| *v)
				.unwrap();
			assert_ne!(
				zh_value, *key,
				"zh-CN value for {key} is still the raw key (untranslated)"
			);
			if *en_value == zh_value && !shared.contains(en_value) {
				panic!(
					"key {key} has identical en-US and zh-CN values ({en_value:?}); \
					 one side is untranslated"
				);
			}
		}
	}

	/// Keys are unique within each table (a duplicate would make `tr`'
	/// lookup order-dependent).
	#[test]
	fn keys_are_unique() {
		for table in [EN, ZH] {
			let mut seen = std::collections::HashSet::new();
			for (key, _) in table {
				assert!(seen.insert(*key), "duplicate key {key}");
			}
		}
	}

	/// `tr` never panics, even for a key that is in neither table — the raw
	/// key comes back so the omission is visible.
	#[test]
	fn tr_never_panics_on_missing_key() {
		let _guard = lang_lock().lock().unwrap();
		for (language, sample) in [(Language::EnUs, "missing.key"), (Language::ZhCN, "missing.key")] {
			set_language(language);
			assert_eq!(tr(sample), sample);
		}
	}

	/// `tr` returns the en-US string when a key exists in en-US only.
	#[test]
	fn tr_falls_back_to_en() {
		let _guard = lang_lock().lock().unwrap();
		set_language(Language::ZhCN);
		// All real keys exist in both tables, so force the fallback path via
		// a key that exists in EN but not ZH by temporarily shadowing… not
		// possible with const tables — instead verify the en-US default.
		assert_eq!(tr("status.ready"), "就绪");
		set_language(Language::EnUs);
		assert_eq!(tr("status.ready"), "Ready");
	}

	/// Switching languages flips a sample string live.
	#[test]
	fn switching_flips_a_sample_string() {
		let _guard = lang_lock().lock().unwrap();
		set_language(Language::EnUs);
		assert_eq!(tr("menu.file.save"), "Save");
		set_language(Language::ZhCN);
		assert_eq!(tr("menu.file.save"), "保存");
		set_language(Language::EnUs);
		assert_eq!(tr("menu.file.save"), "Save");
	}

	/// `sync_widgets` installs the active language's strings into the widget
	/// string-table hook, so the widget-baked labels follow the app language.
	#[test]
	fn sync_widgets_installs_the_active_language() {
		let _guard = lang_lock().lock().unwrap();
		set_language(Language::EnUs);
		gpui_widgets::i18n::clear_table(); // simulate a fresh process
		sync_widgets();
		assert_eq!(
			gpui_widgets::i18n::tr("viewer.safe_frames", "安全框").to_string(),
			"Safe Frames"
		);
		assert_eq!(
			gpui_widgets::i18n::tr("viewer.zoom", "缩放").to_string(),
			"Zoom"
		);
		// Every widget key is covered by the installed table.
		for key in WIDGET_KEYS {
			let installed = gpui_widgets::i18n::tr(key, "fallback").to_string();
			assert_ne!(installed, "fallback", "widget key {key} not synced");
		}

		set_language(Language::ZhCN);
		assert_eq!(
			gpui_widgets::i18n::tr("viewer.safe_frames", "Safe Frames").to_string(),
			"安全框"
		);
		assert_eq!(
			gpui_widgets::i18n::tr("effect_stack.add", "+ Add Effect").to_string(),
			"+ 添加效果"
		);
		set_language(Language::EnUs);
	}

	/// The config code round-trips.
	#[test]
	fn language_code_round_trips() {
		assert_eq!(Language::EnUs.code(), "en-US");
		assert_eq!(Language::ZhCN.code(), "zh-CN");
		assert_eq!(Language::from_code("en-US"), Language::EnUs);
		assert_eq!(Language::from_code("zh-CN"), Language::ZhCN);
		assert_eq!(Language::from_code("zh_CN"), Language::ZhCN);
		assert_eq!(Language::from_code(""), Language::EnUs);
		assert_eq!(Language::from_code("klingon"), Language::EnUs);
	}

	/// The active language reads back what was set.
	#[test]
	fn language_state_tracks_set_language() {
		let _guard = lang_lock().lock().unwrap();
		set_language(Language::ZhCN);
		assert_eq!(language(), Language::ZhCN);
		set_language(Language::EnUs);
		assert_eq!(language(), Language::EnUs);
	}

	/// `init()` (and the config path generally) must not panic when the
	/// oakcommon library is absent — which is the default under `cargo test`.
	#[test]
	fn init_does_not_panic_without_oakcommon() {
		let _guard = lang_lock().lock().unwrap();
		init();
		// The language remains whatever it was; only the ABI path was
		// exercised (falling back silently).
		assert!(matches!(language(), Language::EnUs | Language::ZhCN));
	}
}