src/lib/analytics/fetch.ts

import type { EngagementMetrics, CarouselAnalytics } from '@/types/analytics';

/**
 * Fetch engagement metrics from publisher APIs (Zernio/Postiz).
 * Gracefully falls back to mock data if APIs are unavailable.
 */

async function fetchFromZernio(postId: string): Promise<EngagementMetrics | null> {
  try {
    const apiKey = process.env.ZERNIO_API_KEY;
    if (!apiKey) {
      console.warn('[analytics] ZERNIO_API_KEY not set, using fallback');
      return null;
    }

    const response = await fetch(`https://api.zernio.com/posts/${postId}/metrics`, {
      headers: { Authorization: `Bearer ${apiKey}` },
    });

    if (!response.ok) {
      console.error('[analytics] Zernio API error:', response.status);
      return null;
    }

    const data = await response.json();
    return {
      likes: data.likes || 0,
      comments: data.comments || 0,
      shares: data.shares || 0,
      saves: data.saves || 0,
      impressions: data.impressions || 0,
      reach: data.reach || 0,
      engagement_rate: ((data.likes + data.comments + data.shares) / data.impressions) * 100 || 0,
    };
  } catch (error) {
    console.error('[analytics] fetchFromZernio failed:', error);
    return null;
  }
}

async function fetchFromPostiz(postId: string): Promise<EngagementMetrics | null> {
  try {
    const apiKey = process.env.POSTIZ_API_KEY;
    if (!apiKey) {
      console.warn('[analytics] POSTIZ_API_KEY not set, using fallback');
      return null;
    }

    const response = await fetch(`https://api.postiz.com/posts/${postId}/metrics`, {
      headers: { 'X-API-Key': apiKey },
    });

    if (!response.ok) {
      console.error('[analytics] Postiz API error:', response.status);
      return null;
    }

    const data = await response.json();
    return {
      likes: data.likeCount || 0,
      comments: data.commentCount || 0,
      shares: data.shareCount || 0,
      saves: data.saveCount || 0,
      impressions: data.impressionCount || 0,
      reach: data.reachCount || 0,
      engagement_rate:
        ((data.likeCount + data.commentCount + data.shareCount) / data.impressionCount) * 100 || 0,
    };
  } catch (error) {
    console.error('[analytics] fetchFromPostiz failed:', error);
    return null;
  }
}

function generateMockMetrics(): EngagementMetrics {
  // Realistic mock data for testing without real APIs
  const impressions = Math.floor(Math.random() * 5000) + 500;
  const reach = Math.floor(impressions * 0.7);
  const likes = Math.floor(impressions * 0.08);
  const comments = Math.floor(impressions * 0.02);
  const shares = Math.floor(impressions * 0.01);
  const saves = Math.floor(impressions * 0.03);

  return {
    likes,
    comments,
    shares,
    saves,
    impressions,
    reach,
    engagement_rate: ((likes + comments + shares) / impressions) * 100,
  };
}

/**
 * Fetch engagement metrics for a carousel post.
 * Tries Zernio first, then Postiz, then returns mock data.
 */
export async function getEngagementMetrics(
  carouselId: string,
  platform: 'instagram' | 'threads' | 'linkedin',
  externalPostId?: string
): Promise<EngagementMetrics> {
  // If we have an external post ID from publisher, try real APIs
  if (externalPostId) {
    // Try Zernio first (primary publisher)
    const zernioMetrics = await fetchFromZernio(externalPostId);
    if (zernioMetrics) return zernioMetrics;

    // Try Postiz as fallback
    const postizMetrics = await fetchFromPostiz(externalPostId);
    if (postizMetrics) return postizMetrics;
  }

  // Fall back to mock data (Phase 11: real DB integration in future phases)
  console.warn(`[analytics] No real metrics for carousel ${carouselId}, using mock data`);
  return generateMockMetrics();
}

export async function getRecentCarouselAnalytics(
  limit: number = 10
): Promise<CarouselAnalytics[]> {
  try {
    // Import dynamically so it doesn't break analytics if sqlite is missing in pure web enviroments
    const { getScheduledCarousels } = require('@/lib/scheduler/scheduler');
    const published = await getScheduledCarousels('published');
    
    if (!published || published.length === 0) {
      return [];
    }

    const carouselsWithMetrics: CarouselAnalytics[] = await Promise.all(
      published.slice(0, limit).map(async (carousel: any) => {
        // Grab the first platform from their platforms array, defaulting to instagram
        const platform = (carousel.platforms && carousel.platforms.length > 0) ? carousel.platforms[0] : 'instagram';
        
        return {
          carousel_id: carousel.carouselId,
          title: carousel.title || 'Untitled Post',
          platform: platform as 'instagram' | 'threads' | 'linkedin',
          published_at: carousel.publishedAt || carousel.scheduledFor,
          slide_count: 5, // Default fallback since scheduler doesn't currently store this context
          template_type: 'bold-statement', // Default fallback
          palette: 'blue', // Default fallback
          metrics: await getEngagementMetrics(carousel.carouselId, platform),
        };
      })
    );

    return carouselsWithMetrics.sort(
      (a, b) =>
        new Date(b.published_at).getTime() - new Date(a.published_at).getTime()
    );
  } catch (error) {
    console.error('[analytics] getRecentCarouselAnalytics failed:', error);
    return [];
  }
}