/**
 * Platform and architecture resolution utilities.
 */

function parsePlatforms(input) {
  if (!input || typeof input !== 'string') return [];
  const parts = input.split(',');
  const platforms = [];
  for (const part of parts) {
    const clean = part.trim();
    if (!clean) continue;
    if (!clean.includes('/')) {
      platforms.push(`linux/${clean}`);
    } else {
      platforms.push(clean);
    }
  }
  return platforms;
}

function discoverPlatforms(headRawJson, targetRawJson) {
  const set = new Set();
  for (const raw of [headRawJson, targetRawJson]) {
    if (!raw) continue;
    try {
      const data = JSON.parse(raw);
      const manifests = data.manifests || [];
      for (const m of manifests) {
        if (m.platform && m.platform.architecture && m.platform.architecture !== 'unknown') {
          const os = m.platform.os || 'linux';
          const variant = m.platform.variant ? `/${m.platform.variant}` : '';
          set.add(`${os}/${m.platform.architecture}${variant}`);
        }
      }
    } catch {
      // Ignore JSON parse errors from invalid manifests
    }
  }
  return Array.from(set).sort();
}

function toArchTag(platform) {
  if (!platform) return 'default';
  // Strip optional leading os/ (e.g. linux/)
  const withoutOs = platform.replace(/^[a-zA-Z0-9_-]+\//, '');
  // Replace slashes with dashes (e.g. arm/v7 -> arm-v7)
  return withoutOs.replace(/\//g, '-');
}

module.exports = {
  parsePlatforms,
  discoverPlatforms,
  toArchTag,
};