import { spawn, ChildProcess } from "child_process";
import { execSync } from "child_process";
import path from "path";
import fs from "fs";
import http from "http";
import { createAssetsSymlink, generateAdConfig } from "./configGenerator";

const TEMPLATE_DIR = path.resolve(__dirname, "../../../../templates/coloring");
const PREVIEW_PORT = 5199;

let viteProcess: ChildProcess | null = null;
let currentCreativeId: string | null = null;

/**
 * 等待 HTTP 服务就绪
 */
function waitForReady(url: string, maxRetries = 15): Promise<void> {
  return new Promise((resolve, reject) => {
    let tries = 0;
    function check() {
      http.get(url, (res) => {
        if (res.statusCode === 200) resolve();
        else retry();
      }).on("error", retry);
    }
    function retry() {
      if (++tries >= maxRetries) {
        reject(new Error(`Preview server did not start within ${maxRetries}s`));
        return;
      }
      setTimeout(check, 1000);
    }
    check();
  });
}

/**
 * 启动实时预览。等待 Vite dev server 就绪后才返回。
 */
export async function startPreview(
  creativeId: string,
  theme: Record<string, string>,
  storageDir: string
): Promise<{ url: string }> {
  // 1. 停止旧的预览（如果有）
  stopPreview();

  // 2. 创建 symlink
  createAssetsSymlink(creativeId, storageDir);

  // 3. 生成配置
  const configContent = generateAdConfig({ creativeId, theme, storageDir });
  const configPath = path.join(TEMPLATE_DIR, "src", "filler", "_ad_config_.ts");
  fs.writeFileSync(configPath, configContent, "utf-8");

  // 4. 启动 Vite dev server（base 路径由 PREVIEW_BASE_PATH 环境变量传入 vite.config.js）
  console.log(`[preview] Starting Vite dev server on port ${PREVIEW_PORT}...`);
  viteProcess = spawn("npx", [
    "vite",
    "--port", String(PREVIEW_PORT),
    "--strictPort",
  ], {
    cwd: TEMPLATE_DIR,
    env: {
      ...process.env,
      AD_CONFIG_PATH: "src/filler/_ad_config_.ts",
      PREVIEW_BASE_PATH: process.env.PREVIEW_BASE_PATH || "/",
    },
    stdio: ["ignore", "pipe", "pipe"],
  });

  viteProcess.stdout?.on("data", (data: Buffer) => {
    console.log(`[preview:vite] ${data.toString().trim()}`);
  });
  viteProcess.stderr?.on("data", (data: Buffer) => {
    console.log(`[preview:vite] ${data.toString().trim()}`);
  });
  viteProcess.on("exit", (code) => {
    console.log(`[preview] Vite dev server exited (code ${code})`);
    viteProcess = null;
    currentCreativeId = null;
  });

  currentCreativeId = creativeId;

  // 5. 等待 Vite 就绪
  const localUrl = `http://localhost:${PREVIEW_PORT}`;
  console.log("[preview] Waiting for Vite to be ready...");
  await waitForReady(localUrl);
  console.log("[preview] Vite is ready.");

  // 生产环境通过 nginx 代理暴露公网 URL，本地开发直接用 localhost
  const publicUrl = process.env.PREVIEW_PUBLIC_URL || localUrl;
  return { url: publicUrl };
}

/**
 * 更新预览配置（主题变更时调用）。Vite HMR 会自动检测并刷新页面。
 */
export function updatePreviewConfig(
  creativeId: string,
  theme: Record<string, string>,
  storageDir: string
): void {
  if (currentCreativeId !== creativeId) return;

  const configContent = generateAdConfig({ creativeId, theme, storageDir });
  const configPath = path.join(TEMPLATE_DIR, "src", "filler", "_ad_config_.ts");
  fs.writeFileSync(configPath, configContent, "utf-8");
  console.log(`[preview] Config updated for creative ${creativeId}`);
}

/**
 * 停止预览
 */
export function stopPreview(): void {
  if (viteProcess) {
    console.log("[preview] Stopping Vite dev server...");
    try {
      viteProcess.kill("SIGTERM");
    } catch {
      // ignore
    }
    viteProcess = null;
  }
  currentCreativeId = null;

  // 确保端口释放
  try {
    execSync(`lsof -ti :${PREVIEW_PORT} | xargs kill -9 2>/dev/null`, { stdio: "ignore" });
  } catch {}
}

export function getPreviewStatus(): { active: boolean; creativeId: string | null; url: string | null } {
  return {
    active: viteProcess !== null && currentCreativeId !== null,
    creativeId: currentCreativeId,
    url: currentCreativeId ? `http://localhost:${PREVIEW_PORT}` : null,
  };
}