/**
 * Plugin/skill version-drift detection (issue #274).
 *
 * The Claude Code marketplace installs from the committed `./plugin` subtree,
 * so any version disagreement between the hand-edited manifests and the
 * generated subtree ships stale content reporting a wrong version. Root
 * `.claude-plugin/plugin.json` is the single source of truth (build() reads
 * skillsVersion from it). Every other version-bearing file must match it:
 *
 *   - `.claude-plugin/marketplace.json` plugins[0].version — hand-edited
 *     alongside plugin.json; the post-merge sync workflow can't repair a
 *     mismatch here because it never bumps versions.
 *   - `plugin/.claude-plugin/plugin.json` version — generated, derived from
 *     root at build:release; checked so a bump that forgets to regenerate the
 *     subtree fails loudly instead of merging a drift window onto main.
 *   - `plugin/skills/impeccable/SKILL.md` frontmatter version — generated;
 *     same rationale.
 *   - `dist/openai/impeccable/.codex-plugin/plugin.json` version — generated
 *     for public OpenAI submission and checked when that build output exists.
 *
 * The collector is pure (filesystem-in, data-out) so it can be unit-tested
 * against fixtures; build.js owns the logging and the non-zero exit.
 */
import fs from 'fs';
import path from 'path';

/**
 * Pull the version value out of a SKILL.md leading frontmatter block.
 * CRLF-tolerant (`\r?\n`) to match the shared parseFrontmatter in
 * scripts/lib/utils.js — a bundle saved with CRLF line endings must not read
 * as a null version and trip a false mismatch. Codex builds carry the version
 * under `metadata.version`; legacy provider builds keep the top-level key.
 */
export function readSkillFrontmatterVersion(content) {
  const fm = String(content).match(/^---[ \t]*\r?\n([\s\S]*?)\r?\n---(?:[ \t]*\r?\n|[ \t]*$)/);
  if (!fm) return null;

  let metadataVersion = null;
  let topLevelVersion = null;
  let inMetadata = false;
  let metadataIndent = null;

  for (const line of fm[1].split(/\r?\n/)) {
    if (!line.trim() || line.trimStart().startsWith('#')) continue;
    const indentText = line.match(/^[ \t]*/)[0];
    const indent = indentText.replace(/\t/g, '  ').length;

    if (indent === 0) {
      inMetadata = /^metadata:\s*(?:#.*)?$/.test(line);
      metadataIndent = null;
      const version = line.match(/^version:\s*(.+?)\s*$/);
      if (version) topLevelVersion = version[1];
      continue;
    }

    if (!inMetadata) continue;
    if (metadataIndent === null) metadataIndent = indent;
    if (indent !== metadataIndent) continue;
    const version = line.trim().match(/^version:\s*(.+?)\s*$/);
    if (version) metadataVersion = version[1];
  }

  const value = metadataVersion || topLevelVersion;
  return value ? value.trim().replace(/^(["'])(.*)\1$/, '$2') : null;
}

/**
 * Read a file and extract a value, turning read/parse failures into a clean
 * sentinel instead of a raw throw. A version bump is exactly the moment a
 * manifest is half-edited, so a malformed file must produce an actionable
 * diagnostic naming the file, not a stack trace out of build().
 *
 * @returns {{ value: any } | { error: string }}
 */
function extractFromFile(absPath, extract) {
  let raw;
  try {
    raw = fs.readFileSync(absPath, 'utf-8');
  } catch (err) {
    return { error: `could not read file (${err.code || err.message})` };
  }
  try {
    return { value: extract(raw) };
  } catch (err) {
    return { error: `could not parse (${err.message})` };
  }
}

/**
 * Compare every version-bearing plugin/skill file against root plugin.json.
 *
 * @param {string} rootDir repository root
 * @returns {{
 *   source: string|null,
 *   checked: Array<{relPath:string, found:any}>,
 *   mismatches: Array<{relPath:string, found:any, expected:string}>,
 *   errors: Array<{relPath:string, reason:string}>,
 * }}
 *   `source` is null only when root plugin.json is absent (nothing to check).
 *   A present-but-malformed root, or one missing its `version` field, instead
 *   reports an entry in `errors` so the build fails loudly rather than passing.
 */
export function collectPluginVersions(rootDir) {
  const rootRel = '.claude-plugin/plugin.json';
  const rootManifestPath = path.join(rootDir, rootRel);
  const empty = { source: null, checked: [], mismatches: [], errors: [] };
  if (!fs.existsSync(rootManifestPath)) return empty;

  const rootResult = extractFromFile(rootManifestPath, (raw) => JSON.parse(raw).version);
  if (rootResult.error) {
    return { ...empty, errors: [{ relPath: rootRel, reason: rootResult.error }] };
  }
  const source = rootResult.value;
  if (source == null) {
    return { ...empty, errors: [{ relPath: rootRel, reason: 'missing "version" field' }] };
  }

  const checks = [
    {
      relPath: '.claude-plugin/marketplace.json',
      read: (raw) => JSON.parse(raw).plugins?.[0]?.version,
    },
    {
      relPath: 'plugin/.claude-plugin/plugin.json',
      read: (raw) => JSON.parse(raw).version,
    },
    {
      relPath: 'dist/openai/impeccable/.codex-plugin/plugin.json',
      read: (raw) => JSON.parse(raw).version,
    },
    {
      relPath: 'plugin/skills/impeccable/SKILL.md',
      read: (raw) => readSkillFrontmatterVersion(raw),
    },
  ];

  const checked = [];
  const mismatches = [];
  const errors = [];
  for (const { relPath, read } of checks) {
    const absPath = path.join(rootDir, relPath);
    if (!fs.existsSync(absPath)) continue;
    const result = extractFromFile(absPath, read);
    if (result.error) {
      errors.push({ relPath, reason: result.error });
      continue;
    }
    const found = result.value;
    checked.push({ relPath, found });
    if (found !== source) mismatches.push({ relPath, found, expected: source });
  }

  return { source, checked, mismatches, errors };
}