import { getRedisClient } from '@/lib/redis';
import { logger } from '@/lib/logger';
import { NotificationCount } from '@/lib/types/notification';

export interface NotificationItem {
  id: string;
  title: string;
  message: string;
  link?: string;
  timestamp: string;
  metadata?: Record<string, any>;
}

/**
 * Simple registry that stores notification counts from widgets
 * Widgets update their counts, and the badge reads the aggregated count
 */
export class NotificationRegistry {
  private static instance: NotificationRegistry;
  private static COUNT_CACHE_KEY = (userId: string) => `notifications:count:${userId}`;
  private static ITEMS_CACHE_KEY = (userId: string, source: string) => 
    `notifications:items:${userId}:${source}`;
  private static COUNT_CACHE_TTL = 300; // 5 minutes (increased to prevent premature expiration)
  private static ITEMS_CACHE_TTL = 300; // 5 minutes for items

  public static getInstance(): NotificationRegistry {
    if (!NotificationRegistry.instance) {
      NotificationRegistry.instance = new NotificationRegistry();
    }
    return NotificationRegistry.instance;
  }

  /**
   * Record count from a widget (called when widget detects new items)
   */
  async recordCount(
    userId: string,
    source: string,
    count: number,
    items?: NotificationItem[]
  ): Promise<void> {
    const redis = getRedisClient();
    const cacheKey = NotificationRegistry.COUNT_CACHE_KEY(userId);

    // Get current aggregated count
    let currentCount: NotificationCount = {
      total: 0,
      unread: 0,
      sources: {},
    };

    try {
      const cached = await redis.get(cacheKey);
      if (cached) {
        currentCount = JSON.parse(cached);
      }
    } catch (error) {
      logger.error('[NOTIFICATION_REGISTRY] Error reading cache', {
        userIdHash: Buffer.from(userId).toString('base64').slice(0, 12),
        error: error instanceof Error ? error.message : String(error),
      });
    }

    // Update count for this source
    // If count is 1 and it's a call, increment. Otherwise, set the count.
    const previousSourceCount = currentCount.sources[source]?.unread || 0;
    const isCallIncrement = count === 1 && items && items.length > 0 && items[0].metadata?.type === 'call';
    
    if (isCallIncrement) {
      // For calls, increment the existing count
      currentCount.sources[source] = {
        total: previousSourceCount + count,
        unread: previousSourceCount + count,
      };
      logger.debug('[NOTIFICATION_REGISTRY] Call count incremented', {
        source,
        previousCount: previousSourceCount,
        newCount: currentCount.sources[source].unread,
      });
    } else {
      // For regular updates, set the count (widgets send their total)
      // Only update if the new count is different or if we're setting it for the first time
      if (count !== previousSourceCount || !currentCount.sources[source]) {
        currentCount.sources[source] = {
          total: count,
          unread: count,
        };
        logger.debug('[NOTIFICATION_REGISTRY] Count updated', {
          previousCount: previousSourceCount,
          newCount: count,
        });
      } else {
        // Count hasn't changed, but refresh the TTL to keep it alive
        logger.debug('[NOTIFICATION_REGISTRY] Count unchanged, refreshing TTL', {
          count,
        });
      }
    }

    // Recalculate total
    currentCount.unread = Object.values(currentCount.sources).reduce(
      (sum, s) => sum + s.unread,
      0
    );
    currentCount.total = currentCount.unread;

    // Store in cache
    try {
      await redis.set(
        cacheKey,
        JSON.stringify(currentCount),
        'EX',
        NotificationRegistry.COUNT_CACHE_TTL
      );

      logger.debug('[NOTIFICATION_REGISTRY] Count updated', {
        userIdHash: Buffer.from(userId).toString('base64').slice(0, 12),
        count,
        totalUnread: currentCount.unread,
        previousCount: previousSourceCount,
      });
    } catch (error) {
      logger.error('[NOTIFICATION_REGISTRY] Error updating cache', {
        userIdHash: Buffer.from(userId).toString('base64').slice(0, 12),
        error: error instanceof Error ? error.message : String(error),
      });
    }

    // Store items if provided (for dropdown display)
    if (items && items.length > 0) {
      try {
        const itemsKey = NotificationRegistry.ITEMS_CACHE_KEY(userId, source);
        // Limit to 50 items per source
        await redis.set(
          itemsKey,
          JSON.stringify(items.slice(0, 50)),
          'EX',
          NotificationRegistry.ITEMS_CACHE_TTL
        );

        logger.debug('[NOTIFICATION_REGISTRY] Items stored', {
          userIdHash: Buffer.from(userId).toString('base64').slice(0, 12),
          itemsCount: items.length,
        });
      } catch (error) {
        logger.error('[NOTIFICATION_REGISTRY] Error storing items', {
          userIdHash: Buffer.from(userId).toString('base64').slice(0, 12),
          error: error instanceof Error ? error.message : String(error),
        });
      }
    }
  }

  /**
   * Get aggregated count (called by the badge)
   */
  async getCount(userId: string): Promise<NotificationCount> {
    const redis = getRedisClient();
    const cacheKey = NotificationRegistry.COUNT_CACHE_KEY(userId);

    try {
      const cached = await redis.get(cacheKey);
      if (cached) {
        const count = JSON.parse(cached);
        logger.debug('[NOTIFICATION_REGISTRY] Count retrieved from cache', {
          userIdHash: Buffer.from(userId).toString('base64').slice(0, 12),
          totalUnread: count.unread,
          sourcesCount: Object.keys(count.sources).length,
        });
        return count;
      }
    } catch (error) {
      logger.error('[NOTIFICATION_REGISTRY] Error reading cache', {
        userIdHash: Buffer.from(userId).toString('base64').slice(0, 12),
        error: error instanceof Error ? error.message : String(error),
      });
    }

    // If no cache, return empty count
    logger.debug('[NOTIFICATION_REGISTRY] No cache found, returning empty count', {
      userIdHash: Buffer.from(userId).toString('base64').slice(0, 12),
    });
    return {
      total: 0,
      unread: 0,
      sources: {},
    };
  }

  /**
   * Get notifications (items) from all sources (for dropdown)
   */
  async getNotifications(userId: string, limit: number = 20): Promise<any[]> {
    const redis = getRedisClient();
    const sources = ['email', 'rocketchat', 'leantime', 'calendar'];
    const allItems: any[] = [];

    for (const source of sources) {
      try {
        const itemsKey = NotificationRegistry.ITEMS_CACHE_KEY(userId, source);
        const items = await redis.get(itemsKey);
        if (items) {
          const parsed = JSON.parse(items);
          // Transform items to Notification format
          const transformed = parsed.map((item: NotificationItem) => {
            // Parse timestamp - handle both string and Date
            let timestamp: Date;
            if (typeof item.timestamp === 'string') {
              timestamp = new Date(item.timestamp);
            } else if (item.timestamp && typeof item.timestamp === 'object' && 'getTime' in item.timestamp) {
              // Handle Date object (from JSON.parse)
              timestamp = new Date(item.timestamp as any);
            } else {
              timestamp = new Date(); // Fallback to now
            }
            
            return {
              id: `${source}-${item.id}`,
              source: source as 'leantime' | 'rocketchat' | 'email' | 'calendar',
              sourceId: item.id,
              type: source,
              title: item.title,
              message: item.message,
              link: item.link,
              isRead: false, // Widgets only send unread items
              timestamp,
              priority: 'normal' as const,
              user: {
                id: userId,
              },
              metadata: item.metadata,
            };
          });
          allItems.push(...transformed);
        }
      } catch (error) {
      logger.error('[NOTIFICATION_REGISTRY] Error reading items', {
        error: error instanceof Error ? error.message : String(error),
      });
      }
    }

    // Sort by timestamp (newest first)
    allItems.sort((a, b) => b.timestamp.getTime() - a.timestamp.getTime());

    logger.debug('[NOTIFICATION_REGISTRY] Notifications retrieved', {
      userIdHash: Buffer.from(userId).toString('base64').slice(0, 12),
      total: allItems.length,
      limit,
      returned: Math.min(allItems.length, limit),
    });

    return allItems.slice(0, limit);
  }

  /**
   * Invalidate cache (for force refresh)
   */
  async invalidateCache(userId: string): Promise<void> {
    try {
      const redis = getRedisClient();
      const countKey = NotificationRegistry.COUNT_CACHE_KEY(userId);
      const sources = ['email', 'rocketchat', 'leantime', 'calendar'];
      
      // Delete count cache
      await redis.del(countKey);

      // Delete items caches
      for (const source of sources) {
        const itemsKey = NotificationRegistry.ITEMS_CACHE_KEY(userId, source);
        await redis.del(itemsKey);
      }

      logger.debug('[NOTIFICATION_REGISTRY] Cache invalidated', {
        userIdHash: Buffer.from(userId).toString('base64').slice(0, 12),
      });
    } catch (error) {
      logger.error('[NOTIFICATION_REGISTRY] Error invalidating cache', {
        userIdHash: Buffer.from(userId).toString('base64').slice(0, 12),
        error: error instanceof Error ? error.message : String(error),
      });
    }
  }
}