/**
 * Fun Placeholder - 给 pi 输入框加上有趣的随机提示语
 *
 * 默认「自动识别」系统语言（LANG/LC_ALL/LC_CTYPE 以 zh 开头 → 中文池，否则 English 池）。
 * 可用命令随时切换，选择会持久化（重启后依然生效）：
 *   /placeholder            查看当前状态与用法
 *   /placeholder auto|zh|en|all|off   切换
 * 输入框为空时以浅灰色显示在光标之后。
 * 想改提示语？编辑下方 ZH/EN 数组即可（本地包直接改，npm 包需重发版本）。
 */

import { join } from "node:path";
import { readFileSync, writeFileSync } from "node:fs";
import {
	type ExtensionAPI,
	CustomEditor,
	type KeybindingsManager,
	getAgentDir,
} from "@earendil-works/pi-coding-agent";
import {
	type TUI,
	type EditorTheme,
	type AutocompleteItem,
	visibleWidth,
} from "@earendil-works/pi-tui";

// ── 中文提示语池 ──────────────────────────────────────────────────
const ZH_PLACEHOLDERS = [
	"╰(*°▽°*)╯ 想好要让 pi 帮你做什么了吗？",
	"✨ 在这里输入你的魔法咒语...",
	"🎯 一个 prompt 改变世界，开始吧",
	"🤖 人类，请下达指令！",
	"💡 灵感来了？快打出来！",
	"🦊 别问我是狐狸还是浣熊，先问你的问题",
	"🎪 欢迎来到 pi 马戏团，请输入你的节目单",
	"🍵 摸鱼时间到... 哦你已经在了",
	"🚀 正在等待来自人类的输入...",
	"🌈 输入任何内容，奇迹就会发生",
	"⚡ 别光看着，说点什么！",
	"🎮 按 Enter 开始冒险",
	"📝 我有一个好主意，但你先说",
	"🔥 今天的代码写了吗？",
	"💤 Zzz... 哦你来了！问吧",
	"🎲 你的键盘在呼唤你",
	"🌟 行家一出手，就知有没有",
	"🥷 别紧张，我不会笑你的 bug 的（可能）",
	"🔮 你想修什么 bug？说出来让我乐呵乐呵",
	"🎭 假装我是莎士比亚，请给 prompt",
	"🪄 Expecto Prompt-o!",
	"🧩 拼图已经准备好了，就差你的一块",
	"⚙️ *风扇呼呼转* 正在等待任务...",
	"📡 信号已连接，等待你的指令",
	"🌙 深夜写代码？注意休息呀",
	"🍕 写代码饿了？我也帮不了你订餐... 但可以帮你写代码",
	"🧠 脑细胞已就绪，请发送刺激",
];

// ── English placeholder pool ─────────────────────────────────────
const EN_PLACEHOLDERS = [
	"🐞 Found a bug? Let's squash it together!",
	"🚀 Ready for liftoff. Just type your mission...",
	"🎬 Action! Your script, my execution.",
	"🤯 Enter your prompt and watch the magic.",
	"💻 Keyboard go click clack... make it count!",
	"🔮 I see... a prompt in your future.",
	"🎲 Roll the dice! (Or just type something)",
	"☕ 0xCAFEBABE — brew some code.",
	"🦄 This prompt will be legendary. I can feel it.",
	"🏗️ 0 errors, 0 warnings... so far.",
	"🎪 Step right up! Ask your burning question!",
	"🌊 The answer is out there. Start typing.",
	"🔧 I fix bugs while you sleep. And while you're awake too.",
	"📖 Every great program starts with a single prompt.",
	"🎯 You aim, I fire. What's the target?",
	"⚡ Compiling patience module... done. Ready!",
	"🌀 Go ahead, make my day. With a prompt.",
	"♲ Not all those who wander are lost. But you found pi.",
	"📝 Your wish is my `execute()` command.",
	"🎭 I'm listening... and I don't even have ears!",
];

// 混合池 = 中文 + 英文
const ALL_PLACEHOLDERS = [...ZH_PLACEHOLDERS, ...EN_PLACEHOLDERS];

// ── 模式 ─────────────────────────────────────────────────────────
// auto = 默认，按系统语言自动识别；zh/en/all 固定池；off = 关闭提示语
type Mode = "auto" | "zh" | "en" | "all" | "off";
const MODES: readonly Mode[] = ["auto", "zh", "en", "all", "off"];

function isMode(v: string): v is Mode {
	return (MODES as readonly string[]).includes(v);
}

// ── 配置持久化（~/.pi/agent/fun-placeholder.json）──────────────
const CONFIG_FILE = join(getAgentDir(), "fun-placeholder.json");

function loadMode(): Mode {
	try {
		const raw = readFile(CONFIG_FILE);
		if (raw !== null) {
			const parsed = JSON.parse(raw) as { mode?: unknown };
			if (typeof parsed.mode === "string" && isMode(parsed.mode)) {
				return parsed.mode;
			}
		}
	} catch {
		// 配置损坏 → 回退默认
	}
	return "auto";
}

function readFile(path: string): string | null {
	try {
		return readFileSync(path, "utf8");
	} catch {
		return null;
	}
}

function saveMode(mode: Mode): void {
	try {
		writeFileSync(CONFIG_FILE, JSON.stringify({ mode }, null, "\t") + "\n");
	} catch {
		// 写入失败不阻塞命令（仅本次运行生效）
	}
}

// ── 语言识别 ─────────────────────────────────────────────────────
function detectZhLocale(): boolean {
	const lang = (
		process.env.LC_ALL ??
		process.env.LC_CTYPE ??
		process.env.LANG ??
		""
	).toLowerCase();
	return lang.startsWith("zh");
}

function resolvePool(mode: Mode): { list: string[]; label: string } {
	switch (mode) {
		case "zh":
			return { list: ZH_PLACEHOLDERS, label: "中文" };
		case "en":
			return { list: EN_PLACEHOLDERS, label: "English" };
		case "all":
			return { list: ALL_PLACEHOLDERS, label: "中英混合" };
		case "off":
			return { list: [], label: "关闭" };
		case "auto":
			return detectZhLocale()
				? { list: ZH_PLACEHOLDERS, label: "自动识别（中文环境）" }
				: { list: EN_PLACEHOLDERS, label: "自动识别（非中文环境）" };
	}
}

function describeMode(mode: Mode): string {
	const { list, label } = resolvePool(mode);
	return list.length > 0 ? `${label}（${list.length} 条）` : label;
}

function pickRandom(list: string[]): string {
	return list.length === 0 ? "" : list[Math.floor(Math.random() * list.length)]!;
}

// 模块级当前模式：session_start 与命令共享同一状态
let currentMode: Mode = loadMode();

// ── 自定义编辑器 ──────────────────────────────────────────────────
class PlaceholderEditor extends CustomEditor {
	private placeholder: string;

	constructor(tui: TUI, theme: EditorTheme, keybindings: KeybindingsManager) {
		super(tui, theme, keybindings);
		// 构建时按当前模式抽取一条；off 时为空字符串 = 不显示提示语
		this.placeholder = pickRandom(resolvePool(currentMode).list);
	}

	/**
	 * 当编辑器为空时，在光标位置后显示主题色提示语
	 */
	override render(width: number): string[] {
		// 非空或已关闭：正常渲染
		if (this.getText() !== "" || this.placeholder === "") {
			return super.render(width);
		}

		// 空编辑器：先渲染正常框架（边框 + 空行 + 光标）
		const lines = super.render(width);
		if (lines.length < 3) return lines;

		// 空编辑器时 lines 结构:
		//   [0] = 顶边框 (ANSI 包裹的 ── 线)
		//   [1] = 内容行: 左padding + CURSOR_MARKER + 反色空格光标 + 右padding
		//   [2] = 底边框

		const contentLine = lines[1]!;

		// 找到反色空格光标的位置
		// 光标渲染为: CURSOR_MARKER + \x1b[7m \x1b[0m
		const cursorSeq = `\x1b[7m \x1b[0m`;
		const cursorEnd = contentLine.indexOf(cursorSeq) + cursorSeq.length;
		if (cursorEnd < cursorSeq.length) return lines; // 没找到光标，回退

		// 光标之后的所有内容 (= 填充 padding + 右padding)
		const afterCursor = contentLine.slice(cursorEnd);

		// 光标之前的内容 (= 左padding + CURSOR_MARKER)
		const beforeCursor = contentLine.slice(0, cursorEnd);

		// 计算可用的填充宽度
		const afterCursorWidth = visibleWidth(afterCursor);

		// 构建提示语文本（浅灰色）
		const placeholder = "\x1b[38;5;250m" + this.placeholder + "\x1b[0m";
		const placeholderWidth = visibleWidth(this.placeholder);

		// 根据剩余空间决定是否截断
		const newPaddingWidth = Math.max(0, afterCursorWidth - placeholderWidth);

		// 重建内容行
		lines[1] =
			beforeCursor +
			placeholder +
			" ".repeat(newPaddingWidth);

		return lines;
	}
}

// ── 扩展入口 ──────────────────────────────────────────────────────
export default function (pi: ExtensionAPI) {
	pi.on("session_start", (_event, ctx) => {
		ctx.ui.setEditorComponent(
			(tui, theme, keybindings) => new PlaceholderEditor(tui, theme, keybindings),
		);
	});

	pi.registerCommand("placeholder", {
		description: "切换输入框提示语: auto(识别) / zh / en / all / off",
		getArgumentCompletions: (prefix: string): AutocompleteItem[] | null => {
			const items = MODES.map((m) => ({ value: m, label: m }));
			const filtered = items.filter((i) => i.value.startsWith(prefix));
			return filtered.length > 0 ? filtered : null;
		},
		handler: async (args, ctx) => {
			const arg = (args ?? "").trim().toLowerCase();

			// 无参数：显示当前状态
			if (arg === "") {
				ctx.ui.notify(
					`提示语当前: ${describeMode(currentMode)}。用法: /placeholder auto|zh|en|all|off`,
					"info",
				);
				return;
			}

			// 非法参数：提示用法
			if (!isMode(arg)) {
				ctx.ui.notify(`未知模式 "${arg}"。用法: /placeholder auto|zh|en|all|off`, "error");
				return;
			}

			// 切换模式并持久化
			currentMode = arg;
			saveMode(arg);

			// 重建编辑器，让新模式立即生效（命令执行后输入框已清空，无内容丢失风险）
			if (ctx.hasUI) {
				ctx.ui.setEditorComponent(
					(tui, theme, keybindings) => new PlaceholderEditor(tui, theme, keybindings),
				);
			}

			ctx.ui.notify(`提示语已切换 → ${describeMode(arg)}`, "info");
		},
	});
}