import { BadRequestException, ForbiddenException, Inject, Injectable, UnauthorizedException } from '@nestjs/common';
import { AccessCore, Permission } from 'src/cores/access.core';
import { AssetIdErrorReason, AssetIdsResponseDto } from 'src/dtos/asset-ids.response.dto';
import { AssetIdsDto } from 'src/dtos/asset.dto';
import { AuthDto } from 'src/dtos/auth.dto';
import {
  SharedLinkCreateDto,
  SharedLinkEditDto,
  SharedLinkPasswordDto,
  SharedLinkResponseDto,
  mapSharedLink,
  mapSharedLinkWithoutMetadata,
} from 'src/dtos/shared-link.dto';
import { AssetEntity } from 'src/entities/asset.entity';
import { SharedLinkEntity, SharedLinkType } from 'src/entities/shared-link.entity';
import { IAccessRepository } from 'src/interfaces/access.interface';
import { ICryptoRepository } from 'src/interfaces/crypto.interface';
import { ISharedLinkRepository } from 'src/interfaces/shared-link.interface';
import { OpenGraphTags } from 'src/utils/misc';

@Injectable()
export class SharedLinkService {
  private access: AccessCore;

  constructor(
    @Inject(IAccessRepository) accessRepository: IAccessRepository,
    @Inject(ICryptoRepository) private cryptoRepository: ICryptoRepository,
    @Inject(ISharedLinkRepository) private repository: ISharedLinkRepository,
  ) {
    this.access = AccessCore.create(accessRepository);
  }

  getAll(auth: AuthDto): Promise<SharedLinkResponseDto[]> {
    return this.repository.getAll(auth.user.id).then((links) => links.map((link) => mapSharedLink(link)));
  }

  async getMine(auth: AuthDto, dto: SharedLinkPasswordDto): Promise<SharedLinkResponseDto> {
    if (!auth.sharedLink) {
      throw new ForbiddenException();
    }

    const sharedLink = await this.findOrFail(auth.user.id, auth.sharedLink.id);
    const response = this.mapToSharedLink(sharedLink, { withExif: sharedLink.showExif });
    if (sharedLink.password) {
      response.token = this.validateAndRefreshToken(sharedLink, dto);
    }

    return response;
  }

  async get(auth: AuthDto, id: string): Promise<SharedLinkResponseDto> {
    const sharedLink = await this.findOrFail(auth.user.id, id);
    return this.mapToSharedLink(sharedLink, { withExif: true });
  }

  async create(auth: AuthDto, dto: SharedLinkCreateDto): Promise<SharedLinkResponseDto> {
    switch (dto.type) {
      case SharedLinkType.ALBUM: {
        if (!dto.albumId) {
          throw new BadRequestException('Invalid albumId');
        }
        await this.access.requirePermission(auth, Permission.ALBUM_SHARE, dto.albumId);
        break;
      }

      case SharedLinkType.INDIVIDUAL: {
        if (!dto.assetIds || dto.assetIds.length === 0) {
          throw new BadRequestException('Invalid assetIds');
        }

        await this.access.requirePermission(auth, Permission.ASSET_SHARE, dto.assetIds);

        break;
      }
    }

    const sharedLink = await this.repository.create({
      key: this.cryptoRepository.randomBytes(50),
      userId: auth.user.id,
      type: dto.type,
      albumId: dto.albumId || null,
      assets: (dto.assetIds || []).map((id) => ({ id }) as AssetEntity),
      description: dto.description || null,
      password: dto.password,
      expiresAt: dto.expiresAt || null,
      allowUpload: dto.allowUpload ?? true,
      allowDownload: dto.allowDownload ?? true,
      showExif: dto.showMetadata ?? true,
    });

    return this.mapToSharedLink(sharedLink, { withExif: true });
  }

  async update(auth: AuthDto, id: string, dto: SharedLinkEditDto) {
    await this.findOrFail(auth.user.id, id);
    const sharedLink = await this.repository.update({
      id,
      userId: auth.user.id,
      description: dto.description,
      password: dto.password,
      expiresAt: dto.changeExpiryTime && !dto.expiresAt ? null : dto.expiresAt,
      allowUpload: dto.allowUpload,
      allowDownload: dto.allowDownload,
      showExif: dto.showMetadata,
    });
    return this.mapToSharedLink(sharedLink, { withExif: true });
  }

  async remove(auth: AuthDto, id: string): Promise<void> {
    const sharedLink = await this.findOrFail(auth.user.id, id);
    await this.repository.remove(sharedLink);
  }

  // TODO: replace `userId` with permissions and access control checks
  private async findOrFail(userId: string, id: string) {
    const sharedLink = await this.repository.get(userId, id);
    if (!sharedLink) {
      throw new BadRequestException('Shared link not found');
    }
    return sharedLink;
  }

  async addAssets(auth: AuthDto, id: string, dto: AssetIdsDto): Promise<AssetIdsResponseDto[]> {
    const sharedLink = await this.findOrFail(auth.user.id, id);

    if (sharedLink.type !== SharedLinkType.INDIVIDUAL) {
      throw new BadRequestException('Invalid shared link type');
    }

    const existingAssetIds = new Set(sharedLink.assets.map((asset) => asset.id));
    const notPresentAssetIds = dto.assetIds.filter((assetId) => !existingAssetIds.has(assetId));
    const allowedAssetIds = await this.access.checkAccess(auth, Permission.ASSET_SHARE, notPresentAssetIds);

    const results: AssetIdsResponseDto[] = [];
    for (const assetId of dto.assetIds) {
      const hasAsset = existingAssetIds.has(assetId);
      if (hasAsset) {
        results.push({ assetId, success: false, error: AssetIdErrorReason.DUPLICATE });
        continue;
      }

      const hasAccess = allowedAssetIds.has(assetId);
      if (!hasAccess) {
        results.push({ assetId, success: false, error: AssetIdErrorReason.NO_PERMISSION });
        continue;
      }

      results.push({ assetId, success: true });
      sharedLink.assets.push({ id: assetId } as AssetEntity);
    }

    await this.repository.update(sharedLink);

    return results;
  }

  async removeAssets(auth: AuthDto, id: string, dto: AssetIdsDto): Promise<AssetIdsResponseDto[]> {
    const sharedLink = await this.findOrFail(auth.user.id, id);

    if (sharedLink.type !== SharedLinkType.INDIVIDUAL) {
      throw new BadRequestException('Invalid shared link type');
    }

    const results: AssetIdsResponseDto[] = [];
    for (const assetId of dto.assetIds) {
      const hasAsset = sharedLink.assets.find((asset) => asset.id === assetId);
      if (!hasAsset) {
        results.push({ assetId, success: false, error: AssetIdErrorReason.NOT_FOUND });
        continue;
      }

      results.push({ assetId, success: true });
      sharedLink.assets = sharedLink.assets.filter((asset) => asset.id !== assetId);
    }

    await this.repository.update(sharedLink);

    return results;
  }

  async getMetadataTags(auth: AuthDto): Promise<null | OpenGraphTags> {
    if (!auth.sharedLink || auth.sharedLink.password) {
      return null;
    }

    const sharedLink = await this.findOrFail(auth.sharedLink.userId, auth.sharedLink.id);
    const assetId = sharedLink.album?.albumThumbnailAssetId || sharedLink.assets[0]?.id;
    const assetCount = sharedLink.assets.length > 0 ? sharedLink.assets.length : sharedLink.album?.assets.length || 0;

    return {
      title: sharedLink.album ? sharedLink.album.albumName : 'Public Share',
      description: sharedLink.description || `${assetCount} shared photos & videos`,
      imageUrl: assetId
        ? `/api/asset/thumbnail/${assetId}?key=${sharedLink.key.toString('base64url')}`
        : '/feature-panel.png',
    };
  }

  private mapToSharedLink(sharedLink: SharedLinkEntity, { withExif }: { withExif: boolean }) {
    return withExif ? mapSharedLink(sharedLink) : mapSharedLinkWithoutMetadata(sharedLink);
  }

  private validateAndRefreshToken(sharedLink: SharedLinkEntity, dto: SharedLinkPasswordDto): string {
    const token = this.cryptoRepository.hashSha256(`${sharedLink.id}-${sharedLink.password}`);
    const sharedLinkTokens = dto.token?.split(',') || [];
    if (sharedLink.password !== dto.password && !sharedLinkTokens.includes(token)) {
      throw new UnauthorizedException('Invalid password');
    }

    if (!sharedLinkTokens.includes(token)) {
      sharedLinkTokens.push(token);
    }
    return sharedLinkTokens.join(',');
  }
}