// apps/box-app-api/src/feature/homepage/homepage.service.ts
import { Injectable, Logger } from '@nestjs/common';
import { RedisService } from '@box/db/redis/redis.service';
import { tsCacheKeys } from '@box/common/cache/ts-cache-key.provider';
import { nowSecBigInt } from '@box/common/time/time.util';
import { AdType } from '@prisma/mongo/client';
import type { AdPoolEntry } from '@box/common/ads/ad-types';
import { PrismaMongoService } from '../../prisma/prisma-mongo.service';
import { VideoService } from '../video/video.service';
import {
  HomeAdsDto,
  HomeAdDto,
  AnnouncementDto,
  CategoryDto,
  WaterfallAdsDto,
  PopupAdsDto,
  FloatingAdsDto,
} from './dto/homepage.dto';
import { RecommendedVideosDto } from '../video/dto';
import {
  AdOrder,
  SystemParamSide,
  ANNOUNCEMENT_KEYWORD,
  AdSlot,
} from './homepage.constants';
import type { HomeCategoryCacheItem, HomeTagCacheItem } from './homepage.types';

@Injectable()
export class HomepageService {
  private readonly logger = new Logger(HomepageService.name);

  constructor(
    private readonly redis: RedisService,
    private readonly prisma: PrismaMongoService,
    private readonly videoService: VideoService,
  ) {}

  /**
   * Get complete homepage data in single API call
   */
  async getHomepageData(): Promise<{
    ads: HomeAdsDto;
    announcements: AnnouncementDto[];
    categories: CategoryDto[];
    videos: RecommendedVideosDto;
  }> {
    const [ads, announcements, categories, videos] = await Promise.all([
      this.getHomeAds(),
      this.getAnnouncements(),
      this.getCategories(),
      this.videoService.getRecommendedVideos(),
    ]);
    return {
      ads,
      announcements,
      categories,
      videos,
    };
  }

  /**
   * Fetch all ads for homepage
   */
  private async getHomeAds(): Promise<HomeAdsDto> {
    const [carousel, banner, waterfall, popup, floating] = await Promise.all([
      this.getAdsByType(AdType.CAROUSEL, AdOrder.RANDOM),
      this.getSingleAd(AdType.BANNER),
      this.getWaterfallAds(),
      this.getPopupAds(),
      this.getFloatingAds(),
    ]);

    return {
      carousel,
      banner,
      waterfall,
      popup,
      floating,
    };
  }

  /**
   * Get waterfall ads (icons, texts, videos)
   */
  private async getWaterfallAds(): Promise<WaterfallAdsDto> {
    const [icons, texts, videos] = await Promise.all([
      this.getAdsByType(AdType.WATERFALL_ICON, AdOrder.RANDOM),
      this.getAdsByType(AdType.WATERFALL_TEXT, AdOrder.RANDOM),
      this.getAdsByType(AdType.WATERFALL_VIDEO, AdOrder.RANDOM),
    ]);

    return { icons, texts, videos };
  }

  /**
   * Get popup ads (multi-step flow)
   */
  private async getPopupAds(): Promise<PopupAdsDto> {
    const [allIcons, images, official] = await Promise.all([
      this.getAdsByType(AdType.POPUP_ICON, AdOrder.RANDOM),
      this.getAdsByType(AdType.POPUP_IMAGE, AdOrder.RANDOM),
      this.getAdsByType(AdType.POPUP_OFFICIAL, AdOrder.SEQUENTIAL),
    ]);

    // Limit icons to max 6
    const icons = allIcons.slice(0, 6);

    return { icons, images, official };
  }

  /**
   * Get floating ads (bottom & edge)
   */
  private async getFloatingAds(): Promise<FloatingAdsDto> {
    const [bottom, edge] = await Promise.all([
      this.getAdsByType(AdType.FLOATING_BOTTOM, AdOrder.RANDOM),
      this.getAdsByType(AdType.FLOATING_EDGE, AdOrder.RANDOM),
    ]);

    return { bottom, edge };
  }

  /**
   * Generic method to fetch ads by type from pool
   */
  private async getAdsByType(
    adType: AdType,
    order: AdOrder,
  ): Promise<HomeAdDto[]> {
    const poolKey = tsCacheKeys.ad.poolByType(adType);

    let pool: AdPoolEntry[] | null = null;
    try {
      const entries = await this.redis.getJson<AdPoolEntry[]>(poolKey);

      if (!entries) {
        this.logger.warn(
          `Ad pool cache miss for adType=${adType}, key=${poolKey}. Cache may be cold; ensure cache-sync rebuilt pools.`,
        );
        return [];
      }

      if (!entries.length) {
        this.logger.warn(`Ad pool empty for adType=${adType}, key=${poolKey}`);
        return [];
      }

      pool = entries;
    } catch (err) {
      if (err instanceof Error && err.message?.includes('WRONGTYPE')) {
        this.logger.warn(
          `Ad pool key ${poolKey} has wrong type, deleting incompatible key`,
        );
        try {
          await this.redis.del(poolKey);
          this.logger.log(
            `Deleted incompatible ad pool key ${poolKey}. It will be rebuilt on next cache warmup.`,
          );
        } catch (delErr) {
          this.logger.error(
            `Failed to delete incompatible key ${poolKey}`,
            delErr instanceof Error ? delErr.stack : String(delErr),
          );
        }
      } else {
        this.logger.error(
          `Failed to read ad pool for adType=${adType}, key=${poolKey}`,
          err instanceof Error ? err.stack : String(err),
        );
      }
    }

    if (!pool) {
      return [];
    }

    // Shuffle if random order
    const sortedPool = order === AdOrder.RANDOM ? this.shuffle(pool) : pool;

    // Fetch all ads in parallel
    const adPromises = sortedPool.map((entry) => this.fetchAdDetails(entry.id));
    const ads = await Promise.all(adPromises);

    // Filter out nulls and map to DTO
    return ads.filter((ad): ad is HomeAdDto => ad !== null);
  }

  /**
   * Get single ad (e.g., banner)
   */
  private async getSingleAd(adType: AdType): Promise<HomeAdDto | null> {
    const ads = await this.getAdsByType(adType, AdOrder.RANDOM);
    return ads.length > 0 ? ads[0] : null;
  }

  /**
   * Fetch ad details from per-ad cache
   */
  private async fetchAdDetails(adId: string): Promise<HomeAdDto | null> {
    try {
      const now = nowSecBigInt();
      const ad = await this.prisma.ads.findUnique({
        where: { id: adId },
        select: {
          id: true,
          adType: true,
          advertiser: true,
          title: true,
          adsContent: true,
          adsCoverImg: true,
          adsUrl: true,
          startDt: true,
          expiryDt: true,
          status: true,
        },
      });

      if (!ad) {
        this.logger.debug(`Ad not found for homepage slot: adId=${adId}`);
        return null;
      }

      if (ad.status !== 1 || ad.startDt > now) {
        return null;
      }

      if (ad.expiryDt !== BigInt(0) && ad.expiryDt < now) {
        return null;
      }

      return {
        id: ad.id,
        adType: ad.adType ?? 'UNKNOWN',
        title: ad.title ?? '',
        advertiser: ad.advertiser ?? '',
        content: ad.adsContent ?? undefined,
        coverImg: ad.adsCoverImg ?? undefined,
        targetUrl: ad.adsUrl ?? undefined,
      };
    } catch (err) {
      this.logger.error(
        `Failed to fetch ad ${adId}`,
        err instanceof Error ? err.stack : String(err),
      );
      return null;
    }
  }

  /**
   * Get slot name for ad type (maps to ADTYPE_POOLS config)
   */
  private getSlotForType(adType: AdType): string {
    const slotMap: Record<AdType, AdSlot> = {
      [AdType.STARTUP]: AdSlot.STARTUP,
      [AdType.CAROUSEL]: AdSlot.CAROUSEL,
      [AdType.POPUP_ICON]: AdSlot.MIDDLE,
      [AdType.POPUP_IMAGE]: AdSlot.MIDDLE,
      [AdType.POPUP_OFFICIAL]: AdSlot.MIDDLE,
      [AdType.WATERFALL_ICON]: AdSlot.WATERFALL,
      [AdType.WATERFALL_TEXT]: AdSlot.WATERFALL,
      [AdType.WATERFALL_VIDEO]: AdSlot.WATERFALL,
      [AdType.FLOATING_BOTTOM]: AdSlot.FLOATING,
      [AdType.FLOATING_EDGE]: AdSlot.EDGE,
      [AdType.BANNER]: AdSlot.TOP,
      [AdType.PREROLL]: AdSlot.PREROLL,
      [AdType.PAUSE]: AdSlot.PAUSE_OVERLAY,
    };

    return slotMap[adType] ?? AdSlot.UNKNOWN;
  }

  /**
   * Get announcements (marquee notices)
   * Using SystemParam with side='client' and specific naming convention
   */
  private async getAnnouncements(): Promise<AnnouncementDto[]> {
    try {
      // Fetch client-side params that could be announcements
      // Convention: params with name starting with 'announcement_' or 'notice_'
      const params = await this.prisma.systemParam.findMany({
        where: {
          side: SystemParamSide.CLIENT,
          name: {
            contains: ANNOUNCEMENT_KEYWORD,
          },
        },
        orderBy: {
          id: 'asc', // sequential order by ID
        },
      });

      return params.map((p, idx) => ({
        id: p.id.toString(),
        content: p.value ?? '', // Use 'value' field as content
        seq: idx,
      }));
    } catch (error) {
      this.logger.warn(
        'Error fetching announcements from SystemParam, returning empty',
      );
      return [];
    }
  }

  /**
   * Get video categories (delegated to VideoService)
   */
  private async getCategories(): Promise<CategoryDto[]> {
    return this.videoService.getCategories();
  }

  async getCategoryTags(channelId: string): Promise<any[]> {
    try {
      const cacheKey = `category:tag:${channelId}`;
      const cache = await this.redis.getJson<HomeCategoryCacheItem[]>(cacheKey);
      if (cache) {
        return cache;
      }

      this.logger.log(`Cache miss for category tags of channelId=${channelId}`);

      const channel = await this.prisma.channel.findUnique({
        where: { channelId },
        // select: {
        //   categories: true,
        // },
      });
      this.logger.log(
        `Fetched channel data for channelId=${channelId}: ${JSON.stringify(channel)}`,
      );

      type ChannelCategory = {
        id: string;
        name?: string;
      };

      const categoryIds =
        (channel?.categories as ChannelCategory[] | null)?.map((c) => c.id) ??
        [];

      const categories = await this.prisma.category.findMany({
        where: {
          id: { in: categoryIds },
        },
        select: {
          name: true,
          subtitle: true,
          tagNames: true,
        },
        orderBy: {
          seq: 'desc',
        },
      });

      if (categories.length > 0) {
        await this.redis.setJson(cacheKey, categories, 24 * 3600);
      }

      return categories;
    } catch (err) {
      this.logger.error(
        `Error fetching home section videos for channelId=${channelId}`,
        err instanceof Error ? err.stack : String(err),
      );
      return [];
    }
  }

  async getCategoryList(): Promise<HomeCategoryCacheItem[]> {
    const raw = await this.redis.get(tsCacheKeys.category.all());
    return this.parseCategoryCache(raw);
  }

  async getTagList(): Promise<HomeTagCacheItem[] | Record<string, unknown>> {
    const raw = await this.redis.get(tsCacheKeys.tag.all());
    if (!raw) {
      return [];
    }

    try {
      const parsed = JSON.parse(raw);
      if (Array.isArray(parsed)) {
        return parsed as HomeTagCacheItem[];
      }
      if (parsed && typeof parsed === 'object') {
        return parsed as Record<string, unknown>;
      }
    } catch {
      this.logger.warn('Failed to parse tag list from Redis cache');
    }

    return [];
  }

  async searchByCategoryName(q: string): Promise<HomeCategoryCacheItem[]> {
    const term = q?.trim();
    if (!term) {
      return [];
    }

    const lowercaseTerm = term.toLowerCase();
    const categories = await this.getCategoryList();
    return categories.filter((category) =>
      category.name.toLowerCase().includes(lowercaseTerm),
    );
  }

  async searchByTagName(q: string): Promise<HomeCategoryCacheItem[]> {
    const term = q?.trim();
    if (!term) {
      return [];
    }

    const lowercaseTerm = term.toLowerCase();
    const categories = await this.getCategoryList();
    return categories.filter((category) =>
      category.tags.some((tag) => tag.toLowerCase().includes(lowercaseTerm)),
    );
  }

  private parseCategoryCache(raw: string | null): HomeCategoryCacheItem[] {
    if (!raw) {
      return [];
    }

    let parsed: unknown;
    try {
      parsed = JSON.parse(raw);
    } catch {
      this.logger.warn('Failed to parse category list from Redis cache');
      return [];
    }

    if (!Array.isArray(parsed)) {
      return [];
    }

    const entries: HomeCategoryCacheItem[] = [];
    let hadInvalidEntry = false;
    for (const entry of parsed) {
      if (!this.isValidCategoryEntry(entry)) {
        hadInvalidEntry = true;
        continue;
      }

      const candidate = entry as HomeCategoryCacheItem;
      entries.push({
        id: candidate.id,
        name: candidate.name,
        subtitle: candidate.subtitle,
        seq: candidate.seq,
        tags: candidate.tags,
      });
    }

    if (hadInvalidEntry) {
      this.logger.warn('Skipped invalid entries while parsing category cache');
    }

    return entries.sort((a, b) => a.seq - b.seq);
  }

  private isValidCategoryEntry(entry: unknown): entry is HomeCategoryCacheItem {
    if (!entry || typeof entry !== 'object') {
      return false;
    }

    const candidate = entry as Record<string, unknown>;
    if (
      typeof candidate.id !== 'string' ||
      typeof candidate.name !== 'string'
    ) {
      return false;
    }

    const seq = candidate.seq;
    if (typeof seq !== 'number' || Number.isNaN(seq)) {
      return false;
    }

    const subtitle = candidate.subtitle;
    if (
      subtitle !== undefined &&
      subtitle !== null &&
      typeof subtitle !== 'string'
    ) {
      return false;
    }

    const tags = candidate.tags;
    if (!Array.isArray(tags) || tags.some((tag) => typeof tag !== 'string')) {
      return false;
    }

    return true;
  }

  /**
   * Get recommended videos (delegated to VideoService)
   */
  // private async getRecommendedVideos(): Promise<RecommendedVideosDto> {
  //   return this.videoService.getRecommendedVideos();
  // }

  /**
   * Fisher-Yates shuffle for random ordering
   */
  private shuffle<T>(array: T[]): T[] {
    const shuffled = [...array];
    for (let i = shuffled.length - 1; i > 0; i--) {
      const j = Math.floor(Math.random() * (i + 1));
      [shuffled[i], shuffled[j]] = [shuffled[j], shuffled[i]];
    }
    return shuffled;
  }
}