#!/usr/bin/env node
/**
 * patch.js — Applies BYOK + premium-unlock patches to a GDevelop source tree.
 *
 * Reads a declarative manifest of patch entries (JSON), each using a
 * "finder / replacer / verify" sandwich.  Supports --strict, --dry-run,
 * --verbose, --manifest, --repo, and --release flags.
 *
 * Usage:
 *   node scripts/patch.js --release v5.6.269
 *   node scripts/patch.js --repo test/fixtures --strict
 *   node scripts/patch.js --repo test/fixtures --dry-run --verbose
 *   node scripts/patch.js --manifest custom/manifest.json --repo my/repo
 *
 * Constraints: Node.js built-in modules only (no npm dependencies).
 */

const fs = require('fs');
const path = require('path');
const { loadManifest, STEPS } = require('../patch/manifest');

// ── CLI flag parsing ─────────────────────────────────────────────────────

const argv = process.argv;

function flagValue(flag) {
  const i = argv.indexOf(flag);
  return i >= 0 && i + 1 < argv.length ? argv[i + 1] : null;
}

function hasFlag(flag) {
  return argv.includes(flag);
}

const RELEASE_TAG = flagValue('--release') || 'unknown';
const ROOT = flagValue('--repo') || process.cwd();
const MANIFEST_PATH = flagValue('--manifest') || path.join(process.cwd(), 'patch', 'manifest.json');
const STRICT = hasFlag('--strict');
const DRY_RUN = hasFlag('--dry-run');
const VERBOSE = hasFlag('--verbose');

// ── Helpers ──────────────────────────────────────────────────────────────

/**
 * Print a message if --verbose is active.
 */
function verbose(msg) {
  if (VERBOSE) console.error(`[verbose] ${msg}`);
}

/**
 * Truncate a string for display (single-line, max 80 chars).
 */
function preview(s) {
  const oneLine = s.replace(/\n/g, '\\n');
  return oneLine.length > 70 ? oneLine.slice(0, 67) + '...' : oneLine;
}

/**
 * Format a structured error to stderr and return it.
 */
function structuredError(patchId, file, step) {
  const msg = `PATCH_FAIL:${patchId}:${file}:${step}`;
  console.error(msg);
  return msg;
}

// ── Core engine ──────────────────────────────────────────────────────────

/**
 * Apply a single manifest entry against the repo.
 *
 * @param {object}   entry   Manifest entry with id, file, finder, replacer, verify, required, description.
 * @param {string}   root    Absolute repo root path.
 * @returns {object}         { pass: boolean, step: string|null, msg: string }
 */
function applyEntry(entry, root) {
  const filePath = path.join(root, entry.file);

  // ── Step 0: file must exist ──
  if (!fs.existsSync(filePath)) {
    return { pass: false, step: 'finder', msg: `file not found: ${entry.file}` };
  }

  const original = fs.readFileSync(filePath, 'utf8');

  // ── Step 1: finder regex must match exactly once ──
  let finderRegex;
  try {
    finderRegex = new RegExp(entry.finder, 'gm');
  } catch (e) {
    return { pass: false, step: STEPS.finder, msg: `finder regex compile error: ${e.message}` };
  }

  const finderMatches = [...original.matchAll(new RegExp(finderRegex.source, finderRegex.flags))];

  verbose(`${entry.id}: finder matches = ${finderMatches.length}`);
  if (VERBOSE && finderMatches.length > 0) {
    for (const m of finderMatches) {
      verbose(`${entry.id}: finder match at index ${m.index}: "${preview(m[0])}"`);
    }
  }

  if (DRY_RUN) {
    console.log(`[DRY] ${entry.id}: finder matches ${finderMatches.length} time(s) in ${entry.file}`);
    if (finderMatches.length !== 1) {
      return { pass: false, step: STEPS.finder,
        msg: `finder matches ${finderMatches.length} time(s) (expected 1)` };
    }
    return { pass: true, step: null, msg: `dry-run ok` };
  }

  if (finderMatches.length !== 1) {
    return { pass: false, step: STEPS.finder,
      msg: `finder matches ${finderMatches.length} time(s) in ${entry.file} (expected exactly 1)` };
  }

  verbose(`${entry.id}: applying replacer`);

  // ── Step 2: apply replacer ──
  const patched = original.replace(new RegExp(finderRegex.source, finderRegex.flags), entry.replacer);

  if (patched === original) {
    return { pass: false, step: STEPS.replacer, msg: `replacer did not change file content` };
  }

  // ── Step 3: verify regex must match exactly once in the result ──
  let verifyRegex;
  try {
    verifyRegex = new RegExp(entry.verify, 'gm');
  } catch (e) {
    return { pass: false, step: STEPS.verify, msg: `verify regex compile error: ${e.message}` };
  }

  const verifyMatches = [...patched.matchAll(new RegExp(verifyRegex.source, verifyRegex.flags))];

  verbose(`${entry.id}: verify matches = ${verifyMatches.length}`);
  if (VERBOSE && verifyMatches.length > 0) {
    for (const m of verifyMatches) {
      verbose(`${entry.id}: verify match at index ${m.index}: "${preview(m[0])}"`);
    }
  }

  if (verifyMatches.length !== 1) {
    return { pass: false, step: STEPS.verify,
      msg: `verify matches ${verifyMatches.length} time(s) (expected exactly 1)` };
  }

  // ── Write back ──
  try {
    fs.writeFileSync(filePath, patched, 'utf8');
  } catch (e) {
    return { pass: false, step: STEPS.verify, msg: `write error: ${e.message}` };
  }

  return { pass: true, step: null, msg: 'ok' };
}

// ── Main ─────────────────────────────────────────────────────────────────

function main() {
  const repoRoot = path.resolve(ROOT);

  if (VERBOSE) {
    console.error(`[verbose] repo root   : ${repoRoot}`);
    console.error(`[verbose] manifest    : ${MANIFEST_PATH}`);
    console.error(`[verbose] strict mode : ${STRICT}`);
    console.error(`[verbose] dry-run     : ${DRY_RUN}`);
    console.error(`[verbose] release     : ${RELEASE_TAG}`);
  }

  // 1. Load and validate manifest
  const { entries, errors } = loadManifest(MANIFEST_PATH, repoRoot);

  if (errors.length > 0) {
    console.error('[ERROR] Manifest validation failed:');
    for (const err of errors) console.error(`  - ${err}`);
    process.exit(2);
  }

  const requiredCount = entries.filter(e => e.required).length;
  const optionalCount = entries.filter(e => !e.required).length;
  console.log(`[manifest] ${entries.length} entries (${requiredCount} required, ${optionalCount} optional)`);

  if (entries.length === 0) {
    console.log('[manifest] No entries — nothing to apply.');
    if (DRY_RUN) {
      console.log('[DRY] Dry-run complete. No changes made.');
    }
    return;
  }

  // 2. Apply each entry
  let failures = 0;
  let requiredFailures = 0;

  for (const entry of entries) {
    const result = applyEntry(entry, repoRoot);

    if (result.pass) {
      if (DRY_RUN) {
        // already printed in applyEntry
      } else {
        console.log(`[PASS] ${entry.id}: ${entry.description}`);
      }
    } else {
      failures++;
      const errLine = structuredError(entry.id, entry.file, result.step);
      if (VERBOSE) {
        console.error(`  detail: ${result.msg}`);
      } else {
        console.error(`  (${result.msg})`);
      }

      if (entry.required) {
        requiredFailures++;
      }
    }
  }

  // 3. Summary
  if (DRY_RUN) {
    console.log(`\n[DONE] Dry-run complete. ${entries.length} entries previewed.`);
  } else {
    console.log(`\n[DONE] Applied: ${entries.length - failures} succeeded, ${failures} failed (${requiredFailures} required).`);
  }

  // 4. Exit code
  if (STRICT && requiredFailures > 0) {
    console.error(`\n[FAIL] ${requiredFailures} required patch(es) failed in strict mode.`);
    process.exit(1);
  }
}

main();