import fs = require('fs');
import os = require('os');
import path = require('path');
import zlib = require('zlib');
import https = require('https');
import child_process = require('child_process');

declare const ESBUILD_VERSION: string;

const version = ESBUILD_VERSION;
const binPath = path.join(__dirname, 'bin', 'esbuild');

async function installBinaryFromPackage(name: string, fromPath: string, toPath: string): Promise<void> {
  // Try to install from the cache if possible
  const cachePath = getCachePath(name);
  try {
    // Copy from the cache
    fs.copyFileSync(cachePath, toPath);
    fs.chmodSync(toPath, 0o755);

    // Verify that the binary is the correct version
    validateBinaryVersion(toPath);

    // Mark the cache entry as used for LRU
    const now = new Date;
    fs.utimesSync(cachePath, now, now);
    return;
  } catch {
  }

  // Next, try to install using npm. This should handle various tricky cases
  // such as environments where requests to npmjs.org will hang (in which case
  // there is probably a proxy and/or a custom registry configured instead).
  let buffer: Buffer | undefined;
  let didFail = false;
  try {
    buffer = installUsingNPM(name, fromPath);
  } catch (err) {
    didFail = true;
    console.error(`Trying to install "${name}" using npm`);
    console.error(`Failed to install "${name}" using npm: ${err && err.message || err}`);
  }

  // If that fails, the user could have npm configured incorrectly or could not
  // have npm installed. Try downloading directly from npm as a last resort.
  if (!buffer) {
    const url = `https://registry.npmjs.org/${name}/-/${name}-${version}.tgz`;
    console.error(`Trying to download ${JSON.stringify(url)}`);
    try {
      buffer = extractFileFromTarGzip(await fetch(url), fromPath);
    } catch (err) {
      console.error(`Failed to download ${JSON.stringify(url)}: ${err && err.message || err}`);
    }
  }

  // Give up if none of that worked
  if (!buffer) {
    console.error(`Install unsuccessful`);
    process.exit(1);
  }

  // Write out the binary executable that was extracted from the package
  fs.writeFileSync(toPath, buffer, { mode: 0o755 });

  // Verify that the binary is the correct version
  try {
    validateBinaryVersion(toPath);
  } catch (err) {
    console.error(`The version of the downloaded binary is incorrect: ${err && err.message || err}`);
    console.error(`Install unsuccessful`);
    process.exit(1);
  }

  // Also try to cache the file to speed up future installs
  try {
    fs.mkdirSync(path.dirname(cachePath), {
      recursive: true,
      mode: 0o700, // https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html
    });
    fs.copyFileSync(toPath, cachePath);
    cleanCacheLRU(cachePath);
  } catch {
  }

  if (didFail) console.error(`Install successful`);
}

function validateBinaryVersion(binaryPath: string): void {
  const stdout = child_process.execFileSync(binaryPath, ['--version']).toString().trim();
  if (stdout !== version) {
    throw new Error(`Expected ${JSON.stringify(version)} but got ${JSON.stringify(stdout)}`);
  }
}

function getCachePath(name: string): string {
  const home = os.homedir();
  const common = ['esbuild', 'bin', `${name}@${version}`];
  if (process.platform === 'darwin') return path.join(home, 'Library', 'Caches', ...common);
  if (process.platform === 'win32') return path.join(home, 'AppData', 'Local', 'Cache', ...common);

  // https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html
  const XDG_CACHE_HOME = process.env.XDG_CACHE_HOME;
  if (process.platform === 'linux' && XDG_CACHE_HOME && path.isAbsolute(XDG_CACHE_HOME))
    return path.join(XDG_CACHE_HOME, ...common);

  return path.join(home, '.cache', ...common);
}

function cleanCacheLRU(fileToKeep: string): void {
  // Gather all entries in the cache
  const dir = path.dirname(fileToKeep);
  const entries: { path: string, mtime: Date }[] = [];
  for (const entry of fs.readdirSync(dir)) {
    const entryPath = path.join(dir, entry);
    try {
      const stats = fs.statSync(entryPath);
      entries.push({ path: entryPath, mtime: stats.mtime });
    } catch {
    }
  }

  // Only keep the most recent entries
  entries.sort((a, b) => +b.mtime - +a.mtime);
  for (const entry of entries.slice(5)) {
    try {
      fs.unlinkSync(entry.path);
    } catch {
    }
  }
}

function fetch(url: string): Promise<Buffer> {
  return new Promise((resolve, reject) => {
    https.get(url, res => {
      if ((res.statusCode === 301 || res.statusCode === 302) && res.headers.location)
        return fetch(res.headers.location).then(resolve, reject);
      if (res.statusCode !== 200)
        return reject(new Error(`Server responded with ${res.statusCode}`));
      let chunks: Buffer[] = [];
      res.on('data', chunk => chunks.push(chunk));
      res.on('end', () => resolve(Buffer.concat(chunks)));
    }).on('error', reject);
  });
}

function extractFileFromTarGzip(buffer: Buffer, file: string): Buffer {
  try {
    buffer = zlib.unzipSync(buffer);
  } catch (err) {
    throw new Error(`Invalid gzip data in archive: ${err && err.message || err}`);
  }
  let str = (i: number, n: number) => String.fromCharCode(...buffer.subarray(i, i + n)).replace(/\0.*$/, '');
  let offset = 0;
  file = `package/${file}`;
  while (offset < buffer.length) {
    let name = str(offset, 100);
    let size = parseInt(str(offset + 124, 12), 8);
    offset += 512;
    if (!isNaN(size)) {
      if (name === file) return buffer.subarray(offset, offset + size);
      offset += (size + 511) & ~511;
    }
  }
  throw new Error(`Could not find ${JSON.stringify(file)} in archive`);
}

function installUsingNPM(name: string, file: string): Buffer {
  const installDir = path.join(os.tmpdir(), 'esbuild-' + Math.random().toString(36).slice(2));
  fs.mkdirSync(installDir, { recursive: true });
  fs.writeFileSync(path.join(installDir, 'package.json'), '{}');

  // Erase "npm_config_global" so that "npm install --global esbuild" works.
  // Otherwise this nested "npm install" will also be global, and the install
  // will deadlock waiting for the global installation lock.
  const env = { ...process.env, npm_config_global: undefined };

  child_process.execSync(`npm install --loglevel=error --prefer-offline --no-audit --progress=false ${name}@${version}`,
    { cwd: installDir, stdio: 'pipe', env });
  const buffer = fs.readFileSync(path.join(installDir, 'node_modules', name, file));
  try {
    removeRecursive(installDir);
  } catch (e) {
    // Removing a file or directory can randomly break on Windows, returning
    // EBUSY for an arbitrary length of time. I think this happens when some
    // other program has that file or directory open (e.g. an anti-virus
    // program). This is fine on Unix because the OS just unlinks the entry
    // but keeps the reference around until it's unused. In this case we just
    // ignore errors because this directory is in a temporary directory, so in
    // theory it should get cleaned up eventually anyway.
  }
  return buffer;
}

function removeRecursive(dir: string): void {
  for (const entry of fs.readdirSync(dir)) {
    const entryPath = path.join(dir, entry);
    let stats;
    try {
      stats = fs.lstatSync(entryPath);
    } catch (e) {
      continue; // Guard against https://github.com/nodejs/node/issues/4760
    }
    if (stats.isDirectory()) removeRecursive(entryPath);
    else fs.unlinkSync(entryPath);
  }
  fs.rmdirSync(dir);
}

function isYarnBerryOrNewer(): boolean {
  const { npm_config_user_agent } = process.env;
  if (npm_config_user_agent) {
    const match = npm_config_user_agent.match(/yarn\/(\d+)/);
    if (match && match[1]) {
      return parseInt(match[1], 10) >= 2;
    }
  }
  return false;
}

function installDirectly(name: string) {
  if (process.env.ESBUILD_BINARY_PATH) {
    fs.copyFileSync(process.env.ESBUILD_BINARY_PATH, binPath);
    validateBinaryVersion(binPath);
  } else {
    // Write to a temporary file, then move the file into place. This is an
    // attempt to avoid problems with package managers like pnpm which will
    // usually turn each file into a hard link. We don't want to mutate the
    // hard-linked file which may be shared with other files.
    const tempBinPath = binPath + '__';
    installBinaryFromPackage(name, 'bin/esbuild', tempBinPath)
      .then(() => fs.renameSync(tempBinPath, binPath))
      .catch(e => setImmediate(() => { throw e; }));
  }
}

function installWithWrapper(name: string, fromPath: string, toPath: string): void {
  fs.writeFileSync(
    binPath,
    `#!/usr/bin/env node
const path = require('path');
const esbuild_exe = path.join(__dirname, '..', ${JSON.stringify(toPath)});
const child_process = require('child_process');
const { status } = child_process.spawnSync(esbuild_exe, process.argv.slice(2), { stdio: 'inherit' });
process.exitCode = status === null ? 1 : status;
`);
  const absToPath = path.join(__dirname, toPath);
  if (process.env.ESBUILD_BINARY_PATH) {
    fs.copyFileSync(process.env.ESBUILD_BINARY_PATH, absToPath);
    validateBinaryVersion(absToPath);
  } else {
    installBinaryFromPackage(name, fromPath, absToPath)
      .catch(e => setImmediate(() => { throw e; }));
  }
}

function installOnUnix(name: string): void {
  // Yarn 2 is deliberately incompatible with binary modules because the
  // developers of Yarn 2 don't think they should be used. See this thread for
  // details: https://github.com/yarnpkg/berry/issues/882.
  //
  // We want to avoid slowing down esbuild for everyone just because of this
  // decision by the Yarn 2 developers, so we explicitly detect if esbuild is
  // being installed using Yarn 2 and install a compatability shim only for
  // Yarn 2. Normal package managers can just run the binary directly for
  // maximum speed.
  if (isYarnBerryOrNewer()) {
    installWithWrapper(name, "bin/esbuild", "esbuild");
  } else {
    installDirectly(name);
  }
}

function installOnWindows(name: string): void {
  installWithWrapper(name, "esbuild.exe", "esbuild.exe");
}

const platformKey = `${process.platform} ${os.arch()} ${os.endianness()}`;
const knownWindowsPackages: Record<string, string> = {
  'win32 ia32 LE': 'esbuild-windows-32',
  'win32 x64 LE': 'esbuild-windows-64',
};
const knownUnixlikePackages: Record<string, string> = {
  'android arm64 LE': 'esbuild-android-arm64',
  'darwin arm64 LE': 'esbuild-darwin-arm64',
  'darwin x64 LE': 'esbuild-darwin-64',
  'freebsd arm64 LE': 'esbuild-freebsd-arm64',
  'freebsd x64 LE': 'esbuild-freebsd-64',
  'linux arm LE': 'esbuild-linux-arm',
  'linux arm64 LE': 'esbuild-linux-arm64',
  'linux ia32 LE': 'esbuild-linux-32',
  'linux mips64el LE': 'esbuild-linux-mips64le',
  'linux ppc64 LE': 'esbuild-linux-ppc64le',
  'linux x64 LE': 'esbuild-linux-64',
};

// Pick a package to install
if (platformKey in knownWindowsPackages) {
  installOnWindows(knownWindowsPackages[platformKey]);
} else if (platformKey in knownUnixlikePackages) {
  installOnUnix(knownUnixlikePackages[platformKey]);
} else {
  console.error(`Unsupported platform: ${platformKey}`);
  process.exit(1);
}
