#!/usr/bin/env node
'use strict';

/**
 * Single source for MSD's published-package coordinates (issue #498).
 *
 * `deriveIdentity(pkg)` is the pure core: it turns a parsed package.json into
 * the coordinate record every consumer needs. The generated runtime module
 * `msd-core/bin/lib/package-identity.cjs` bakes those values at build
 * time, because the installed tree carries no package.json with a `.name` —
 * the only ones MSD stages are synthetic `{"type":"commonjs"}` markers, which
 * since #2544 live inside MSD's own directories (`hooks/`, and the native
 * plugin dir) rather than at the config root — so a runtime
 * `require('package.json').name` resolves to `undefined` (the #378 bug this
 * seam retires). Baking from package.json reconciles #378 (renames survive)
 * with #2992 (the value is never an LLM runtime choice).
 */

/**
 * Parse `owner/name` out of a package.json `repository.url`, stripping the
 * `git+` prefix and `.git` suffix npm conventionally adds.
 */
function parseRepo(repository) {
  const url = typeof repository === 'string' ? repository : (repository && repository.url) || '';
  const m = url.replace(/^git\+/, '').replace(/\.git$/, '').match(/(github\.com|git\.golem15\.com)[/:]([^/]+\/[^/]+)$/);
  return m ? { host: m[1], slug: m[2] } : { host: '', slug: '' };
}

function parseRepoSlug(repository) {
  return parseRepo(repository).slug;
}

/**
 * Raw-file URL for CHANGELOG.md on the repo's default branch. GitHub serves raw
 * files from a separate host; the golem15 Gitea forge serves them in-place.
 */
function changelogRawUrlFor(host, slug) {
  if (!slug) return '';
  if (host === 'github.com') return `https://raw.githubusercontent.com/${slug}/main/CHANGELOG.md`;
  return `https://${host}/${slug}/raw/branch/next/CHANGELOG.md`;
}

/**
 * Pure: turn an npm package name into a filesystem-safe slug for cache filenames.
 * Strips a leading `@`, replaces `/` with `-`, then collapses any run of
 * characters that are NOT `[a-z0-9]` to a single `-`, and trims leading/trailing `-`.
 */
function slugifyPackageName(name) {
  if (!name) return '';
  return name
    .replace(/^@/, '')
    .replace(/\//g, '-')
    .toLowerCase()
    .replace(/[^a-z0-9]+/g, '-')
    .replace(/^-+|-+$/g, '');
}

/**
 * Pure: package.json object -> the package identity coordinates.
 */
function deriveIdentity(pkg = {}) {
  const packageName = pkg.name || '';
  const binName = pkg.bin ? Object.keys(pkg.bin)[0] || '' : '';
  const { host, slug: repoSlug } = parseRepo(pkg.repository);
  const repoUrl = repoSlug ? `https://${host}/${repoSlug}` : '';
  const changelogRawUrl = changelogRawUrlFor(host, repoSlug);
  const cacheSlug = slugifyPackageName(packageName);
  const updateCacheFileName = cacheSlug ? `msd-update-check-${cacheSlug}.json` : 'msd-update-check.json';
  return { packageName, binName, repoSlug, repoUrl, changelogRawUrl, cacheSlug, updateCacheFileName };
}

/**
 * Pure: format the `npx` fallback install command. Shape matches the literal
 * the update workflow embeds: `npx -y --package=<pkg>@latest -- <bin>
 * [--<runtime>] --<scope>`. The runtime flag is omitted when not supplied.
 *
 * This function is the canonical source — `render()` serializes it verbatim
 * into the generated module, so the runtime copy can never drift from it.
 */
function formatManualInstall({ packageName, binName, scope, runtime } = {}) {
  const runtimeFlag = runtime ? ` --${runtime}` : '';
  return `npx -y --package=${packageName}@latest -- ${binName}${runtimeFlag} --${scope}`;
}

const GENERATED_HEADER =
  '// @generated by scripts/generate-package-identity.cjs from package.json — DO NOT EDIT.\n' +
  '// Single source for MSD package coordinates (issue #498). Regenerate with:\n' +
  '//   node scripts/generate-package-identity.cjs\n';

/**
 * Render the generated runtime module text for a derived identity. Values are
 * baked as literals; `formatManualInstall` is embedded by `.toString()` so the
 * runtime command builder is byte-identical to the tested source above.
 */
function render(identity) {
  const { packageName, binName, repoSlug, repoUrl, changelogRawUrl, cacheSlug, updateCacheFileName } = identity;
  const j = (v) => JSON.stringify(v);
  return (
    GENERATED_HEADER +
    "'use strict';\n\n" +
    `const packageName = ${j(packageName)};\n` +
    `const binName = ${j(binName)};\n` +
    `const repoSlug = ${j(repoSlug)};\n` +
    `const repoUrl = ${j(repoUrl)};\n` +
    `const changelogRawUrl = ${j(changelogRawUrl)};\n` +
    `const cacheSlug = ${j(cacheSlug)};\n` +
    `const updateCacheFileName = ${j(updateCacheFileName)};\n\n` +
    `${formatManualInstall.toString()}\n\n` +
    'function manualInstallCommand(opts = {}) {\n' +
    '  return formatManualInstall({ packageName, binName, scope: opts.scope, runtime: opts.runtime });\n' +
    '}\n\n' +
    'module.exports = Object.freeze({\n' +
    '  packageName,\n' +
    '  // PACKAGE_NAME: back-compat alias for #516-era consumers. Baked here, so it\n' +
    "  // survives the installed tree's synthetic package.json (fixes the #378 undefined).\n" +
    '  PACKAGE_NAME: packageName,\n' +
    '  binName,\n' +
    '  repoSlug,\n' +
    '  repoUrl,\n' +
    '  changelogRawUrl,\n' +
    '  cacheSlug,\n' +
    '  updateCacheFileName,\n' +
    '  manualInstallCommand,\n' +
    '});\n'
  );
}

function main() {
  const fs = require('node:fs');
  const path = require('node:path');
  const args = process.argv.slice(2);
  const check = args.includes('--check');
  const pkg = require(path.join(__dirname, '..', 'package.json'));
  const out = path.join(__dirname, '..', 'msd-core', 'bin', 'lib', 'package-identity.cjs');
  const rendered = render(deriveIdentity(pkg));
  if (check) {
    // Compare normalized content so a CRLF checkout (Windows, no .gitattributes
    // eol rule) does not register as stale. Mirrors the in-process check the
    // unit suite used to perform (issue #498) and the convention used by the
    // other gen-* --check generators.
    const norm = (s) => s.replace(/\r\n/g, '\n');
    let committed = '';
    try {
      committed = fs.readFileSync(out, 'utf8');
    } catch (e) {
      if (e.code !== 'ENOENT') throw e;
    }
    if (norm(committed) !== norm(rendered)) {
      process.stderr.write('package-identity.cjs is stale — run: node scripts/generate-package-identity.cjs\n');
      return 1;
    }
    return 0;
  }
  fs.writeFileSync(out, rendered);
  process.stdout.write(`wrote ${path.relative(path.join(__dirname, '..'), out)}\n`);
  return 0;
}

if (require.main === module) {
  const code = main();
  if (typeof code === 'number' && code !== 0) process.exitCode = code;
}

module.exports = { deriveIdentity, parseRepoSlug, slugifyPackageName, formatManualInstall, render, main };