// box-nestjs-monorepo/apps/box-mgnt-api/src/dev/services/video-cache-coverage.service.ts
import { Injectable, Logger } from '@nestjs/common';
import { RedisService } from '@box/db/redis/redis.service';
import { MongoPrismaService } from '@box/db/prisma/mongo-prisma.service';
import { tsCacheKeys } from '@box/common/cache/ts-cache-key.provider';

/**
 * Response structure for video cache coverage check
 */
export interface VideoCacheCoverageResponse {
  totalChannels: number;
  totalCategories: number;
  totalTags: number;
  missingCategoryVideoLists: string[];
  missingTagVideoLists: string[];
  missingTagMetadataLists: string[];
}

/**
 * Service for checking video cache coverage.
 * Dev-only: verifies that all expected cache keys exist in Redis.
 *
 * Compares database structure (channels, categories, tags) with actual Redis keys
 * to identify missing cache entries.
 *
 * Smart detection:
 * - Only reports missing category video list if videos exist and Redis key is missing
 * - Only reports missing tag video list if videos exist and Redis key is missing
 * - Tag metadata lists always checked (expected if category has tags)
 */
@Injectable()
export class VideoCacheCoverageService {
  private readonly logger = new Logger(VideoCacheCoverageService.name);

  constructor(
    private readonly redis: RedisService,
    private readonly mongoPrisma: MongoPrismaService,
  ) {}

  /**
   * Check video cache coverage across all channels, categories, and tags.
   * Identifies missing category lists, tag lists, and tag metadata lists.
   *
   * SMART MISSING-KEY DETECTION:
   * - Only reports category video list as missing if: videoCount > 0 AND Redis key missing
   * - Only reports tag video list as missing if: videoCount > 0 AND Redis key missing
   * - Tag metadata lists are checked regardless (always expected if tags exist)
   *
   * This avoids false positives for empty categories/tags with no videos.
   */
  async checkCoverage(): Promise<VideoCacheCoverageResponse> {
    this.logger.log('[Coverage] Starting video cache coverage check');

    const missingCategoryVideoLists: string[] = [];
    const missingTagVideoLists: string[] = [];
    const missingTagMetadataLists: string[] = [];

    let totalChannels = 0;
    let totalCategories = 0;
    let totalTags = 0;

    // Get all channels
    const channels = await this.mongoPrisma.channel.findMany();

    totalChannels = channels.length;
    this.logger.debug(`[Coverage] Found ${totalChannels} channels`);

    for (const channel of channels) {
      // Get all enabled categories (no longer tied to channel)
      const categories = await this.mongoPrisma.category.findMany({
        where: { status: 1 },
      });

      for (const category of categories) {
        totalCategories++;

        // Count videos in this category (using same filter as builder)
        const categoryVideoCount = await this.mongoPrisma.videoMedia.count({
          where: {
            categoryIds: { has: category.id },
            status: 'Completed',
            // listStatus: 1, // Only "on shelf" videos
          },
        });

        // Check category video list cache key ONLY if there are videos
        const categoryListKey = tsCacheKeys.video.categoryList(category.id);
        const categoryListExists = await this.redis.exists(categoryListKey);

        if (categoryVideoCount > 0 && !categoryListExists) {
          missingCategoryVideoLists.push(categoryListKey);
          this.logger.warn(
            `[Coverage] Missing category list: ${categoryListKey} (videos: ${categoryVideoCount})`,
          );
        } else if (categoryVideoCount === 0) {
          this.logger.debug(
            `[Coverage] Empty category OK (no videos, no cache required): ${categoryListKey}`,
          );
        }

        // Check tag metadata list cache key for this category
        const tagMetadataKey = tsCacheKeys.tag.metadataByCategory(category.id);
        const tagMetadataExists = await this.redis.exists(tagMetadataKey);

        if (!tagMetadataExists) {
          missingTagMetadataLists.push(tagMetadataKey);
          this.logger.warn(
            `[Coverage] Missing tag metadata list: ${tagMetadataKey}`,
          );
        }

        // Get all enabled tags for this category (no longer filtered by channel)
        const tags = await this.mongoPrisma.tag.findMany({
          where: {
            status: 1,
            categoryId: category.id,
          },
        });

        for (const tag of tags) {
          totalTags++;

          // Count videos with this tag in this category (same filter as builder)
          const tagVideoCount = await this.mongoPrisma.videoMedia.count({
            where: {
              categoryIds: { has: category.id },
              status: 'Completed',
              // listStatus: 1, // Only "on shelf" videos
              // tagIds: { has: tag.id }, // Has this specific tag
            },
          });

          // Check tag-filtered video list cache key ONLY if there are videos
          const tagListKey = tsCacheKeys.video.tagList(category.id, tag.id);
          const tagListExists = await this.redis.exists(tagListKey);

          if (tagVideoCount > 0 && !tagListExists) {
            missingTagVideoLists.push(tagListKey);
            this.logger.warn(
              `[Coverage] Missing tag video list: ${tagListKey} (videos: ${tagVideoCount})`,
            );
          } else if (tagVideoCount === 0) {
            this.logger.debug(
              `[Coverage] Empty tag OK (no videos, no cache required): ${tagListKey}`,
            );
          }
        }
      }
    }

    const totalMissing =
      missingCategoryVideoLists.length +
      missingTagVideoLists.length +
      missingTagMetadataLists.length;

    this.logger.log(
      `[Coverage] Complete: channels=${totalChannels} categories=${totalCategories} tags=${totalTags} missing=${totalMissing}`,
    );

    if (totalMissing > 0) {
      this.logger.warn(
        `[Coverage] Found ${totalMissing} missing cache keys (categoryLists: ${missingCategoryVideoLists.length}, tagLists: ${missingTagVideoLists.length}, tagMetadata: ${missingTagMetadataLists.length})`,
      );
    } else {
      this.logger.log('[Coverage] All expected cache keys exist');
    }

    return {
      totalChannels,
      totalCategories,
      totalTags,
      missingCategoryVideoLists,
      missingTagVideoLists,
      missingTagMetadataLists,
    };
  }
}