import { spawn } from 'node:child_process';
import { existsSync, readFileSync } from 'node:fs';
import http from 'node:http';
import { resolve } from 'node:path';
import { fileURLToPath } from 'node:url';

const appRoot = fileURLToPath(new URL('..', import.meta.url));
const repoRoot = resolve(appRoot, '../..');
const devStackStatePath = resolve(repoRoot, '.app/dev-stack.json');
const viteHost = '127.0.0.1';
const vitePort = 3080;
const viteUrl = `http://${viteHost}:${vitePort}/`;
const viteMarkerUrl = `${viteUrl}__agc_dev_server.json`;
const defaultApiTarget = process.env.RUST_SERVER_TARGET || 'http://127.0.0.1:8082';
const backendDatabase = 'genarrative-game-creator-dev';
const npm = process.platform === 'win32' ? 'npm.cmd' : 'npm';

function readJson(path) {
  if (!existsSync(path)) {
    return null;
  }
  try {
    return JSON.parse(readFileSync(path, 'utf8'));
  } catch {
    return null;
  }
}

function httpGetText(url, timeout = 1000) {
  return new Promise((resolveRequest) => {
    const request = http.get(url, { timeout }, (response) => {
      let body = '';
      response.setEncoding('utf8');
      response.on('data', (chunk) => {
        if (body.length < 4096) {
          body += chunk;
        }
      });
      response.on('end', () => {
        resolveRequest({
          statusCode: response.statusCode ?? 0,
          body,
        });
      });
    });
    request.on('timeout', () => {
      request.destroy();
      resolveRequest(null);
    });
    request.on('error', () => resolveRequest(null));
  });
}

async function isHttpReady(url) {
  const response = await httpGetText(url);
  return Boolean(response && response.statusCode >= 200 && response.statusCode < 300);
}

function readBackendTargets({ requireAgcDatabase = false } = {}) {
  const state = readJson(devStackStatePath);
  const apiServer = state?.services?.['api-server'];
  const spacetime = state?.services?.spacetime;
  const isActive = (service) =>
    service && ['running', 'reused', 'starting'].includes(service.status ?? '');
  const database = typeof state?.database === 'string' ? state.database : '';
  const hasMatchingDatabase = database === backendDatabase;
  const canReuseState = !requireAgcDatabase || hasMatchingDatabase;
  const apiUrl =
    canReuseState && isActive(apiServer) && apiServer.url
      ? apiServer.url
      : requireAgcDatabase
        ? ''
        : defaultApiTarget;
  const spacetimeUrl =
    canReuseState && isActive(spacetime) && spacetime.url
      ? spacetime.url
      : requireAgcDatabase
        ? ''
        : 'http://127.0.0.1:3101';
  return {
    apiUrl,
    spacetimeUrl,
    database,
    hasMatchingDatabase,
  };
}

async function isBackendReady() {
  const { apiUrl, spacetimeUrl, hasMatchingDatabase } = readBackendTargets({
    requireAgcDatabase: true,
  });
  return (
    hasMatchingDatabase &&
    Boolean(apiUrl) &&
    Boolean(spacetimeUrl) &&
    (await isHttpReady(`${apiUrl}/healthz`)) &&
    (await isHttpReady(`${spacetimeUrl}/v1/ping`))
  );
}

async function readExistingViteServer() {
  return httpGetText(viteUrl);
}

function isAiGameCreatorServer(response) {
  return (
    response &&
    response.statusCode >= 200 &&
    response.statusCode < 500 &&
    response.body.includes('<title>AI 游戏创作</title>') &&
    response.body.includes('/src/main.tsx')
  );
}

async function isExistingViteProxyReady() {
  const response = await httpGetText(`${viteUrl}api/auth/me`, 2000);
  return Boolean(
    response &&
      response.statusCode >= 200 &&
      response.statusCode < 500 &&
      !response.body.includes('<title>AI 游戏创作</title>') &&
      !response.body.includes('/src/main.tsx'),
  );
}

async function readExistingViteMarker() {
  const response = await httpGetText(viteMarkerUrl, 2000);
  if (!response || response.statusCode !== 200) {
    return null;
  }
  try {
    return JSON.parse(response.body);
  } catch {
    return null;
  }
}

async function isExistingVitePairedWithBackend(apiTarget) {
  const marker = await readExistingViteMarker();
  return Boolean(
    marker &&
      marker.schemaVersion === 1 &&
      marker.app === 'ai-game-creator-shell' &&
      marker.apiTarget === apiTarget,
  );
}

function spawnChild(command, args, options) {
  return spawn(command, args, {
    ...options,
    shell: true,
    stdio: 'inherit',
  });
}

function stopChild(child, signal = 'SIGTERM') {
  if (!child || child.exitCode != null || child.signalCode != null) {
    return;
  }
  try {
    child.kill(signal);
  } catch {
    // ignore cleanup races
  }
}

async function waitForBackendReady(backendChild, timeoutMs = 600_000) {
  const startedAt = Date.now();
  let backendExit = null;
  backendChild?.on('exit', (code, signal) => {
    backendExit = signal ? `signal=${signal}` : `code=${code ?? 0}`;
  });
  while (Date.now() - startedAt < timeoutMs) {
    if (await isBackendReady()) {
      return readBackendTargets();
    }
    if (backendExit) {
      throw new Error(`配套后端启动失败: ${backendExit}`);
    }
    await new Promise((resolveWait) => setTimeout(resolveWait, 1000));
  }
  throw new Error('等待配套后端和数据库启动超时');
}

async function ensureBackend() {
  if (await isBackendReady()) {
    const targets = readBackendTargets();
    console.log(`[ai-game-creator-shell] reuse backend ${targets.apiUrl}`);
    return { backendChild: null, targets };
  }

  console.log('[ai-game-creator-shell] starting backend stack');
  const backendChild = spawnChild(
    npm,
    [
      '--prefix',
      '../..',
      'run',
      'agc:backend',
      '--',
      '--database',
      backendDatabase,
      '--no-interactive',
    ],
    { cwd: appRoot },
  );
  const targets = await waitForBackendReady(backendChild);
  console.log(`[ai-game-creator-shell] backend ready ${targets.apiUrl}`);
  return { backendChild, targets };
}

async function startVite(apiTarget) {
  const { apiUrl } = readBackendTargets();
  if (apiUrl !== apiTarget) {
    throw new Error(
      `dev-stack state API target ${apiUrl} does not match paired backend ${apiTarget}.`,
    );
  }

  const existing = await readExistingViteServer();
  if (existing) {
    if (
      isAiGameCreatorServer(existing) &&
      (await isExistingVitePairedWithBackend(apiTarget)) &&
      (await isExistingViteProxyReady())
    ) {
      console.log(`[ai-game-creator-shell] reuse existing Vite dev server ${viteUrl}`);
      return null;
    }
    if (isAiGameCreatorServer(existing)) {
      throw new Error(
        `${viteUrl} is already running, but its /api proxy is not connected to the paired backend. Stop it before starting Tauri dev.`,
      );
    }
    throw new Error(
      `${viteUrl} is already in use by another server. Stop it before starting Tauri dev.`,
    );
  }

  return spawnChild(
    npm,
    ['--prefix', '../..', 'exec', 'vite', '--', '--config', 'vite.config.ts'],
    { cwd: appRoot },
  );
}

let backendChild = null;
let viteChild = null;

for (const signal of ['SIGINT', 'SIGTERM']) {
  process.on(signal, () => {
    stopChild(viteChild, signal);
    stopChild(backendChild, signal);
  });
}

try {
  const backend = await ensureBackend();
  backendChild = backend.backendChild;
  viteChild = await startVite(backend.targets.apiUrl);

  const children = [backendChild, viteChild].filter(Boolean);
  if (children.length === 0) {
    process.exit(0);
  }

  await new Promise((resolveExit) => {
    for (const child of children) {
      child.on('exit', (code, signal) => {
        stopChild(viteChild);
        stopChild(backendChild);
        resolveExit(signal ? 1 : code ?? 0);
      });
    }
  }).then((code) => process.exit(code));
} catch (error) {
  stopChild(viteChild);
  stopChild(backendChild);
  console.error(
    `[ai-game-creator-shell] ${error instanceof Error ? error.message : String(error)}`,
  );
  process.exit(1);
}