import type { ExtensionAPI } from "@earendil-works/pi-coding-agent";
import { stat } from "node:fs/promises";
import { homedir } from "node:os";
import { join, parse, resolve } from "node:path";

interface ExecResult {
	code: number;
	stdout: string;
	stderr: string;
}

export type PluginInitExecutor = (
	command: string,
	args: string[],
	options: { cwd: string },
) => Promise<ExecResult>;

interface InitTarget {
	name: "CodeGraph" | "Hippo";
	command: "codegraph" | "hippo";
	database: string;
	initArgs(cwd: string): string[];
}

const INIT_TARGETS: InitTarget[] = [
	{
		name: "CodeGraph",
		command: "codegraph",
		database: join(".codegraph", "codegraph.db"),
		initArgs: (cwd) => ["init", cwd],
	},
	{
		name: "Hippo",
		command: "hippo",
		database: join(".hippo", "hippo.db"),
		initArgs: () => ["init"],
	},
];

async function isFile(path: string): Promise<boolean> {
	try {
		return (await stat(path)).isFile();
	} catch (error) {
		if (typeof error === "object" && error !== null && "code" in error && error.code === "ENOENT") return false;
		throw error;
	}
}

export function validatePluginInitCwd(cwd: string): string {
	const projectRoot = resolve(cwd);
	if (projectRoot === parse(projectRoot).root) {
		throw new Error("拒绝在文件系统根目录初始化项目插件。");
	}
	if (projectRoot === resolve(homedir())) {
		throw new Error("拒绝直接在用户主目录初始化项目插件；请先进入具体项目目录。");
	}
	return projectRoot;
}

export async function findMissingPluginInitializers(cwd: string): Promise<InitTarget[]> {
	const projectRoot = validatePluginInitCwd(cwd);
	const states = await Promise.all(
		INIT_TARGETS.map(async (target) => ({
			target,
			initialized: await isFile(join(projectRoot, target.database)),
		})),
	);
	return states.filter(({ initialized }) => !initialized).map(({ target }) => target);
}

function compactFailure(result: ExecResult): string {
	const output = (result.stderr.trim() || result.stdout.trim()).replace(/\s+/gu, " ");
	return output ? output.slice(0, 400) : `退出码 ${result.code}`;
}

async function executeChecked(
	exec: PluginInitExecutor,
	target: InitTarget,
	args: string[],
	cwd: string,
	phase: "检测" | "初始化",
): Promise<void> {
	let result: ExecResult;
	try {
		result = await exec(target.command, args, { cwd });
	} catch (error) {
		const detail = error instanceof Error ? error.message : String(error);
		throw new Error(`${target.name} ${phase}失败：${detail}`, { cause: error });
	}
	if (result.code !== 0) {
		throw new Error(`${target.name} ${phase}失败：${compactFailure(result)}`);
	}
}

export async function initializeMissingPlugins(
	cwd: string,
	targets: InitTarget[],
	exec: PluginInitExecutor,
	onStart?: (target: InitTarget) => void,
): Promise<void> {
	const projectRoot = validatePluginInitCwd(cwd);

	// Preflight both CLIs before creating either project's state.
	for (const target of INIT_TARGETS) {
		await executeChecked(exec, target, ["--version"], projectRoot, "检测");
	}
	const completed: InitTarget[] = [];
	for (const target of targets) {
		onStart?.(target);
		try {
			await executeChecked(exec, target, target.initArgs(projectRoot), projectRoot, "初始化");
			completed.push(target);
		} catch (error) {
			if (completed.length === 0) throw error;
			const detail = error instanceof Error ? error.message : String(error);
			throw new Error(
				`${detail}；已完成的 ${completed.map(({ name }) => name).join("、")} 初始化会保留，不会自动回滚。`,
				{ cause: error },
			);
		}
	}
}

export default function pluginInitExtension(pi: ExtensionAPI): void {
	pi.registerCommand("plugin_init", {
		description: "Initialize CodeGraph and Hippo for the current project, then hot-reload Pi",
		handler: async (_args, ctx) => {
			if (!ctx.hasUI) return;

			let projectRoot: string;
			let missing: InitTarget[];
			try {
				projectRoot = validatePluginInitCwd(ctx.cwd);
				missing = await findMissingPluginInitializers(projectRoot);
			} catch (error) {
				ctx.ui.notify(error instanceof Error ? error.message : String(error), "error");
				return;
			}

			const pending = missing.length > 0 ? missing.map(({ name }) => name).join("、") : "无（均已初始化）";
			const confirmed = await ctx.ui.confirm(
				"初始化项目插件",
				`项目：${projectRoot}\n待初始化：${pending}\n\n完成后将热重载 Pi 扩展。是否继续？`,
			);
			if (!confirmed) return;

			try {
				await initializeMissingPlugins(
					projectRoot,
					missing,
					(command, args, options) => pi.exec(command, args, options),
					(target) => ctx.ui.notify(`正在初始化 ${target.name}…`, "info"),
				);
				ctx.ui.notify(
					missing.length > 0 ? "项目插件初始化完成，正在热重载 Pi…" : "项目插件均已初始化，正在热重载 Pi…",
					"info",
				);
				await ctx.reload();
			} catch (error) {
				ctx.ui.notify(error instanceof Error ? error.message : String(error), "error");
			}
		},
	});
}