/**
 * Pure visual-diff verdict logic, split out of crawler.ts so it can be unit-tested
 * without pulling in crawler.ts's full import graph (Playwright, Stagehand, and
 * transitively @detiq/database, which instantiates a PrismaClient at module load and
 * so requires a live DATABASE_URL just to import the module).
 */

export interface VisualDiffVerdict {
  changeType: 'NONE' | 'MINOR' | 'SIGNIFICANT' | 'CRITICAL';
  recommendation: 'APPROVE' | 'REVIEW' | 'FLAG' | 'BLOCK';
  changes: Array<{ location: string; severity: string; description: string }>;
  bugReportDraft?: { title: string; severity: string; steps: string[]; expected: string; actual: string };
  aiSummary?: string;
}

/** Cheap, always-on first-pass verdict from perceptual hash distance + layout/element diffs. */
export function pHashVerdict(
  pHashDistance: number,
  changeLevel: 'IDENTICAL' | 'MINOR' | 'MODERATE' | 'SIGNIFICANT',
  changes: Array<{ location: string; severity: string; description: string }>,
): VisualDiffVerdict {
  const changeType: VisualDiffVerdict['changeType'] = changeLevel === 'IDENTICAL' ? 'NONE'
    : changeLevel === 'MINOR' ? 'MINOR'
      : changeLevel === 'MODERATE' ? 'SIGNIFICANT'
        : 'CRITICAL';
  const approveThreshold = parseInt(process.env.CRAWLER_VISUAL_DIFF_APPROVE_THRESHOLD ?? '') || 5;
  const reviewThreshold = parseInt(process.env.CRAWLER_VISUAL_DIFF_REVIEW_THRESHOLD ?? '') || 20;
  const recommendation: VisualDiffVerdict['recommendation'] = pHashDistance === 0 ? 'APPROVE'
    : pHashDistance < approveThreshold ? 'APPROVE'
      : pHashDistance < reviewThreshold ? 'REVIEW'
        : 'FLAG';
  return { changeType, recommendation, changes };
}

/** Replaces a pHash-only verdict with the AI's semantic judgment once it's available,
 *  and drafts a bug report for anything still CRITICAL/SIGNIFICANT after AI review
 *  (pHash flags plenty of anti-aliasing/font-rendering noise the AI correctly discards
 *  as NONE/MINOR — only what survives AI review is worth a draft). */
export function mergeAiVisualVerdict(
  pHashResult: VisualDiffVerdict,
  aiResult: { changeType: string; changes: any[]; recommendation: string; diffScore: number; summary?: string },
  screenName: string,
): VisualDiffVerdict {
  if (!aiResult.changeType) return pHashResult;
  const changeType = aiResult.changeType as VisualDiffVerdict['changeType'];
  const recommendation = aiResult.recommendation as VisualDiffVerdict['recommendation'];
  const changes = Array.isArray(aiResult.changes) && aiResult.changes.length > 0 ? aiResult.changes : pHashResult.changes;
  const aiSummary = aiResult.summary ?? undefined;
  const bugReportDraft = (changeType === 'CRITICAL' || changeType === 'SIGNIFICANT')
    ? {
        title: `Visual regression on "${screenName}"`,
        severity: changeType === 'CRITICAL' ? 'High' : 'Medium',
        steps: ['Navigate to the screen', 'Compare current view to baseline screenshot'],
        expected: 'Screen appearance should match the stored baseline.',
        actual: aiSummary || `Screen has changed (diff score: ${aiResult.diffScore.toFixed(1)}%)`,
      }
    : undefined;
  return { changeType, recommendation, changes, bugReportDraft, aiSummary };
}