import { execSync } from 'node:child_process';
import { mkdir, writeFile } from 'node:fs/promises';
import path from 'node:path';
import process from 'node:process';

const rootDir = path.resolve(process.cwd());
const publicDir = path.join(rootDir, 'public');
const generatedDir = path.join(rootDir, 'src', 'generated');
const publicVersionPath = path.join(publicDir, '__build_version__.json');
const moduleVersionPath = path.join(generatedDir, 'buildVersion.js');

function readGitShortSha() {
  try {
    return execSync('git rev-parse --short HEAD', {
      cwd: rootDir,
      stdio: ['ignore', 'pipe', 'ignore'],
      encoding: 'utf8',
    }).trim();
  } catch {
    return 'unknown';
  }
}

function readGitFullSha() {
  try {
    return execSync('git rev-parse HEAD', {
      cwd: rootDir,
      stdio: ['ignore', 'pipe', 'ignore'],
      encoding: 'utf8',
    }).trim();
  } catch {
    return 'unknown';
  }
}

function readEnvText(name) {
  const value = String(process.env[name] || '').trim();
  return value || '';
}

function createBuildVersion() {
  const now = new Date();
  const iso = now.toISOString();
  const compact = iso.replace(/[-:TZ.]/g, '').slice(0, 14);
  const buildHostGitSha = readGitShortSha();
  const buildHostGitFullSha = readGitFullSha();
  const sourceGitSha = readEnvText('SOURCE_GIT_SHA') || buildHostGitSha;
  const sourceGitFullSha = readEnvText('SOURCE_GIT_FULL_SHA') || buildHostGitFullSha;
  const sourceGitRef = readEnvText('SOURCE_GIT_REF');
  const sourceMetadataMode = sourceGitSha === buildHostGitSha ? 'git' : 'env';

  return {
    version: `${compact}-${sourceGitSha}`,
    builtAt: iso,
    gitSha: sourceGitSha,
    sourceGitSha,
    sourceGitFullSha,
    sourceGitRef,
    buildHostGitSha,
    buildHostGitFullSha,
    sourceMetadataMode,
  };
}

async function main() {
  const payload = createBuildVersion();
  const jsonContent = `${JSON.stringify(payload, null, 2)}\n`;
  const moduleContent = [
    `export const BUILD_VERSION = ${JSON.stringify(payload.version)};`,
    `export const BUILD_METADATA = ${JSON.stringify(payload, null, 2)};`,
    '',
  ].join('\n');

  await mkdir(publicDir, { recursive: true });
  await mkdir(generatedDir, { recursive: true });
  await writeFile(publicVersionPath, jsonContent, 'utf8');
  await writeFile(moduleVersionPath, moduleContent, 'utf8');
  process.stdout.write(`Wrote build version ${payload.version}\n`);
}

main().catch((error) => {
  process.stderr.write(`${error.message}\n`);
  process.exitCode = 1;
});