/**
 * Bidirectional image harmonize (dev <-> prod) by file mtime.
 *
 * Usage:
 *   npm run harmonize:images
 *   npm run harmonize:images -- --dry-run
 */
const fs = require('fs');
const path = require('path');
const { rootDir, confirmProdAction } = require('./db-env');
const { loadHarmonizeConfig, prodImagesPath } = require('./lib/harmonize-config');
const { printCliResult } = require('./lib/cli-result');

const IMAGE_SUBDIRS = ['portraits', 'paintings'];
const MTIME_TOLERANCE_MS = 1000;

function parseArgs(argv) {
  const configArg = argv.find((a) => a.startsWith('--config='));
  return {
    dryRun: argv.includes('--dry-run'),
    verbose: argv.includes('--verbose'),
    configPath: configArg ? configArg.slice('--config='.length) : null,
  };
}

function resolveDevImageDir() {
  require('dotenv').config({ path: path.join(rootDir, '.env') });
  return path.resolve(process.env.IMAGE_DIR || path.join(rootDir, 'data', 'images'));
}

function walkImageFiles(rootDir, baseRel = '') {
  const files = [];
  const abs = path.join(rootDir, baseRel);
  if (!fs.existsSync(abs)) return files;

  for (const entry of fs.readdirSync(abs, { withFileTypes: true })) {
    const rel = baseRel ? path.join(baseRel, entry.name).replace(/\\/g, '/') : entry.name;
    if (entry.isDirectory()) {
      files.push(...walkImageFiles(rootDir, rel));
    } else if (entry.isFile()) {
      files.push(rel);
    }
  }
  return files;
}

function collectRelativePaths(imageRoot) {
  const relPaths = new Set();
  for (const sub of IMAGE_SUBDIRS) {
    const subRoot = path.join(imageRoot, sub);
    if (!fs.existsSync(subRoot)) continue;
    for (const rel of walkImageFiles(subRoot, sub)) {
      relPaths.add(rel.replace(/\\/g, '/'));
    }
  }
  return relPaths;
}

function statFile(imageRoot, relPath) {
  const abs = path.join(imageRoot, relPath);
  try {
    if (!fs.existsSync(abs)) return null;
    const st = fs.statSync(abs);
    if (!st.isFile()) return null;
    return { size: st.size, mtimeMs: st.mtimeMs };
  } catch {
    return null;
  }
}

function ensureDirForFile(filePath) {
  fs.mkdirSync(path.dirname(filePath), { recursive: true });
}

function copyFile(src, dest, dryRun) {
  if (dryRun) return;
  ensureDirForFile(dest);
  fs.copyFileSync(src, dest);
}

function timestampSlug(date = new Date()) {
  const pad = (n) => String(n).padStart(2, '0');
  return [
    date.getFullYear(),
    pad(date.getMonth() + 1),
    pad(date.getDate()),
    '_',
    pad(date.getHours()),
    pad(date.getMinutes()),
    pad(date.getSeconds()),
  ].join('');
}

async function main() {
  const options = parseArgs(process.argv.slice(2));
  const config = loadHarmonizeConfig(options.configPath);
  const dryRun = options.dryRun || config.dryRun;

  const devDir = resolveDevImageDir();
  const prodDir = prodImagesPath(config);

  if (!fs.existsSync(prodDir)) {
    throw new Error(
      `Prod image path not reachable: ${prodDir}. Map SMB share or set paths.prodImages in harmonize config.`,
    );
  }

  if (!dryRun && process.env.CONFIRM_PROD !== '1') {
    await confirmProdAction(
      'Harmonize will copy image files between dev and prod (prod files may be overwritten).',
    );
  }

  const devPaths = collectRelativePaths(devDir);
  const prodPaths = collectRelativePaths(prodDir);
  const allPaths = new Set([...devPaths, ...prodPaths]);

  const stats = {
    devToProd: 0,
    prodToDev: 0,
    skipped: 0,
    actions: [],
  };

  for (const rel of allPaths) {
    const devStat = statFile(devDir, rel);
    const prodStat = statFile(prodDir, rel);

    if (devStat && !prodStat) {
      stats.devToProd += 1;
      stats.actions.push({ path: rel, action: 'dev→prod copy' });
      copyFile(path.join(devDir, rel), path.join(prodDir, rel), dryRun);
      continue;
    }

    if (prodStat && !devStat) {
      stats.prodToDev += 1;
      stats.actions.push({ path: rel, action: 'prod→dev copy' });
      copyFile(path.join(prodDir, rel), path.join(devDir, rel), dryRun);
      continue;
    }

    if (!devStat || !prodStat) continue;

    const sameSize = devStat.size === prodStat.size;
    const mtimeClose = Math.abs(devStat.mtimeMs - prodStat.mtimeMs) <= MTIME_TOLERANCE_MS;
    if (sameSize && mtimeClose) {
      stats.skipped += 1;
      continue;
    }

    if (devStat.mtimeMs > prodStat.mtimeMs) {
      stats.devToProd += 1;
      stats.actions.push({ path: rel, action: 'dev→prod update' });
      copyFile(path.join(devDir, rel), path.join(prodDir, rel), dryRun);
    } else if (prodStat.mtimeMs > devStat.mtimeMs) {
      stats.prodToDev += 1;
      stats.actions.push({ path: rel, action: 'prod→dev update' });
      copyFile(path.join(prodDir, rel), path.join(devDir, rel), dryRun);
    } else {
      stats.skipped += 1;
    }
  }

  const reportDir = path.join(rootDir, 'db', 'SyncReports');
  fs.mkdirSync(reportDir, { recursive: true });
  const reportPath = path.join(reportDir, `harmonize_images_${timestampSlug()}.json`);
  fs.writeFileSync(reportPath, JSON.stringify({
    generatedAt: new Date().toISOString(),
    dryRun,
    devDir,
    prodDir,
    stats: {
      devToProd: stats.devToProd,
      prodToDev: stats.prodToDev,
      skipped: stats.skipped,
    },
    actions: options.verbose ? stats.actions : stats.actions.slice(0, 500),
  }, null, 2));

  const mode = dryRun ? ' (dry-run)' : '';
  printCliResult({
    script: 'harmonize-images',
    ok: true,
    summary: `Image harmonize complete${mode}: dev→prod ${stats.devToProd}, prod→dev ${stats.prodToDev}, skipped ${stats.skipped}.`,
    details: [`Dev: ${devDir}`, `Prod: ${prodDir}`, `Report: ${reportPath}`],
  });
}

main().catch((err) => {
  printCliResult({
    script: 'harmonize-images',
    ok: false,
    summary: err.message,
  });
});