// box-mgnt-api/src/mgnt-backend/feature/channel/channel.service.ts
import {
  Injectable,
  BadRequestException,
  NotFoundException,
} from '@nestjs/common';
import { PrismaClientKnownRequestError } from '@prisma/client/runtime/library';
import { MongoPrismaService } from '@box/db/prisma/mongo-prisma.service';
import { CacheSyncService } from '../../../cache-sync/cache-sync.service';
import {
  CacheEntityType,
  CacheOperation,
} from '../../../cache-sync/cache-sync.types';
import {
  CreateChannelDto,
  ListChannelDto,
  UpdateChannelDto,
} from './channel.dto';
import { nowSecBigInt } from '@box/common/time/time.util';

@Injectable()
export class ChannelService {
  constructor(
    private readonly mongoPrismaService: MongoPrismaService,
    private readonly cacheSyncService: CacheSyncService,
  ) {}

  /**
   * Current epoch seconds (BigInt) for persisted timestamps.
   *
   * NOTE:
   *  - We now keep `createAt`/`updateAt` as BigInt seconds.
   */
  private now(): bigint {
    return nowSecBigInt();
  }

  private trimOptional(value?: string | null) {
    if (value === undefined) return undefined;
    if (value === null) return null;
    return typeof value === 'string' ? value.trim() : value;
  }

  async create(dto: CreateChannelDto) {
    // Check for duplicate channel name
    const existingChannel = await this.mongoPrismaService.channel.findFirst({
      where: { name: dto.name },
    });

    if (existingChannel) {
      throw new BadRequestException(
        `Channel with name "${dto.name}" already exists`,
      );
    }

    // Check for duplicate channelId
    const existingChannelId = await this.mongoPrismaService.channel.findFirst({
      where: { channelId: dto.channelId },
    });

    if (existingChannelId) {
      throw new BadRequestException(
        `Channel with channelId "${dto.channelId}" already exists`,
      );
    }

    const isDefault = (await this.mongoPrismaService.channel.count()) === 0;

    const now = this.now();

    const channel = await this.mongoPrismaService.channel.create({
      data: {
        channelId: dto.channelId,
        name: dto.name,
        landingUrl: dto.landingUrl,
        videoCdn: this.trimOptional(dto.videoCdn) ?? null,
        coverCdn: this.trimOptional(dto.coverCdn) ?? null,
        clientName: this.trimOptional(dto.clientName) ?? null,
        clientNotice: this.trimOptional(dto.clientNotice) ?? null,
        remark: this.trimOptional(dto.remark) ?? null,
        isDefault,
        categories: (dto.categories as any) || null,
        tags: (dto.tags as any) || null,
        tagNames: dto.tagNames || [],
        createAt: now,
        updateAt: now,
      },
    });

    // Auto-schedule cache refresh
    await this.cacheSyncService.scheduleChannelRefreshAll();
    // Schedule channel-with-categories rebuild for this channel
    await this.cacheSyncService.scheduleAction({
      entityType: CacheEntityType.CHANNEL,
      operation: CacheOperation.REFRESH,
      payload: { channelId: channel.id },
    });

    return channel;
  }

  async update(dto: UpdateChannelDto) {
    // Check for duplicate channel name (excluding current channel)
    const duplicateChannel = await this.mongoPrismaService.channel.findFirst({
      where: {
        name: dto.name,
        id: { not: dto.id },
      },
    });

    if (duplicateChannel) {
      throw new BadRequestException(
        `Channel with name "${dto.name}" already exists`,
      );
    }

    // check for duplicate channelId (excluding current channel)
    const duplicateChannelId = await this.mongoPrismaService.channel.findFirst({
      where: {
        channelId: dto.channelId,
        id: { not: dto.id },
      },
    });

    if (duplicateChannelId) {
      throw new BadRequestException(
        `Channel with channelId "${dto.channelId}" already exists`,
      );
    }

    const now = this.now();

    try {
      const channel = await this.mongoPrismaService.channel.update({
        where: { id: dto.id },
        data: {
          channelId: dto.channelId,
          name: dto.name,
          landingUrl: dto.landingUrl,
          videoCdn: this.trimOptional(dto.videoCdn) ?? null,
          coverCdn: this.trimOptional(dto.coverCdn) ?? null,
          clientName: this.trimOptional(dto.clientName) ?? null,
          clientNotice: this.trimOptional(dto.clientNotice) ?? null,
          remark: this.trimOptional(dto.remark) ?? null,
          categories: (dto.categories as any) || null,
          tags: (dto.tags as any) || null,
          tagNames: dto.tagNames || [],
          updateAt: now,
        },
      });

      // Auto-schedule cache refresh
      await this.cacheSyncService.scheduleChannelRefreshAll();
      // Schedule channel-with-categories rebuild for this channel
      await this.cacheSyncService.scheduleAction({
        entityType: CacheEntityType.CHANNEL,
        operation: CacheOperation.REFRESH,
        payload: { channelId: channel.id },
      });

      return channel;
    } catch (e) {
      if (e instanceof PrismaClientKnownRequestError && e.code === 'P2025') {
        throw new NotFoundException('Channel not found');
      }
      throw e;
    }
  }

  async findOne(id: string) {
    const row = await this.mongoPrismaService.channel.findUnique({
      where: { id },
    });

    if (!row) {
      throw new NotFoundException('Channel not found');
    }

    return row;
  }

  async list(dto: ListChannelDto) {
    const where: any = {};

    if (dto.name) {
      where.name = { contains: dto.name, mode: 'insensitive' };
    }

    // Defensive guards for pagination
    const page = dto.page && dto.page > 0 ? dto.page : 1;
    const size = dto.size && dto.size > 0 ? dto.size : 10;

    const [total, data] = await this.mongoPrismaService.$transaction([
      this.mongoPrismaService.channel.count({ where }),
      this.mongoPrismaService.channel.findMany({
        where,
        orderBy: { updateAt: 'desc' },
        skip: (page - 1) * size,
        take: size,
      }),
    ]);

    return {
      total,
      data,
      totalPages: Math.ceil(total / size),
      page,
      size,
    };
  }

  async remove(id: string) {
    try {
      await this.mongoPrismaService.channel.delete({ where: { id } });

      // Auto-schedule cache refresh
      await this.cacheSyncService.scheduleChannelRefreshAll();

      return { message: 'Deleted' };
    } catch (e) {
      if (e instanceof PrismaClientKnownRequestError && e.code === 'P2025') {
        throw new NotFoundException('Channel not found');
      }
      throw e;
    }
  }
}