import { existsSync } from "node:fs";
import { dirname, join, resolve } from "node:path";
import { fileURLToPath } from "node:url";

const configDir = dirname(fileURLToPath(import.meta.url));
const backendDir = dirname(configDir);
const extensionRoot = resolve(backendDir, "..");

export interface WebUiPaths {
	extensionRoot: string;
	repoRoot: string;
	agentDir: string;
	publicDir: string;
	pidFile: string;
	sessionsDir: string;
	agentExtensionsDir: string;
	agentNpmNodeModules: string;
	agentSettingsFile: string;
	systemPromptFile: string;
	modelsConfigFile: string;
	mcpCacheFile: string;
	mcpConfigFile: string;
	piCliDist: string;
}

export function createWebUiPaths(): WebUiPaths {
	const repoRoot = process.cwd();
	const agentDir = resolve(process.env.PI_CODING_AGENT_DIR || join(repoRoot, ".pi", "agent"));

	return {
		extensionRoot,
		repoRoot,
		agentDir,
		publicDir: join(extensionRoot, "frontend", "dist"),
		pidFile: join(extensionRoot, ".webui.pid"),
		sessionsDir: join(agentDir, "sessions"),
		agentExtensionsDir: join(agentDir, "extensions"),
		agentNpmNodeModules: join(agentDir, "npm", "node_modules"),
		agentSettingsFile: join(agentDir, "settings.json"),
		systemPromptFile: join(agentDir, "AGENTS.md"),
		modelsConfigFile: join(agentDir, "models.json"),
		mcpCacheFile: join(agentDir, "mcp-cache.json"),
		mcpConfigFile: join(agentDir, "mcp.json"),
		piCliDist: join(repoRoot, "packages", "coding-agent", "dist", "cli.js"),
	};
}

export type PiRpcLaunchMode = "dist" | "tsx";

export function resolvePiRpcLaunch(
	paths: WebUiPaths,
): { command: string; args: string[]; mode: PiRpcLaunchMode } {
	const rpcArgs = ["--mode", "rpc"];
	if (existsSync(paths.piCliDist)) {
		return { command: process.execPath, args: [paths.piCliDist, ...rpcArgs], mode: "dist" };
	}

	const tsxCli = join(paths.repoRoot, "node_modules", "tsx", "dist", "cli.mjs");
	const piCliSrc = join(paths.repoRoot, "packages", "coding-agent", "src", "cli.ts");
	if (existsSync(tsxCli) && existsSync(piCliSrc)) {
		return { command: process.execPath, args: [tsxCli, piCliSrc, ...rpcArgs], mode: "tsx" };
	}

	const buildHint =
		process.platform === "win32"
			? "请先运行: npm run build 或 pi-built.bat"
			: "请先运行: npm run build 或 sproutclaw build";
	throw new Error(`[webui] pi 未找到: ${paths.piCliDist}。${buildHint}`);
}