import { BadRequestException, UnauthorizedException } from '@nestjs/common';
import { AuthDto } from 'src/dtos/auth.dto';
import { SharedLinkEntity } from 'src/entities/shared-link.entity';
import { IAccessRepository } from 'src/interfaces/access.interface';
import { setDifference, setIsEqual, setUnion } from 'src/utils/set';

export enum Permission {
  ACTIVITY_CREATE = 'activity.create',
  ACTIVITY_DELETE = 'activity.delete',

  // ASSET_CREATE = 'asset.create',
  ASSET_READ = 'asset.read',
  ASSET_UPDATE = 'asset.update',
  ASSET_DELETE = 'asset.delete',
  ASSET_RESTORE = 'asset.restore',
  ASSET_SHARE = 'asset.share',
  ASSET_VIEW = 'asset.view',
  ASSET_DOWNLOAD = 'asset.download',
  ASSET_UPLOAD = 'asset.upload',

  // ALBUM_CREATE = 'album.create',
  ALBUM_READ = 'album.read',
  ALBUM_UPDATE = 'album.update',
  ALBUM_DELETE = 'album.delete',
  ALBUM_REMOVE_ASSET = 'album.removeAsset',
  ALBUM_SHARE = 'album.share',
  ALBUM_DOWNLOAD = 'album.download',

  AUTH_DEVICE_DELETE = 'authDevice.delete',

  ARCHIVE_READ = 'archive.read',

  TIMELINE_READ = 'timeline.read',
  TIMELINE_DOWNLOAD = 'timeline.download',

  MEMORY_READ = 'memory.read',
  MEMORY_WRITE = 'memory.write',
  MEMORY_DELETE = 'memory.delete',

  PERSON_READ = 'person.read',
  PERSON_WRITE = 'person.write',
  PERSON_MERGE = 'person.merge',
  PERSON_CREATE = 'person.create',
  PERSON_REASSIGN = 'person.reassign',

  PARTNER_UPDATE = 'partner.update',
}

let instance: AccessCore | null;

export class AccessCore {
  private constructor(private repository: IAccessRepository) {}

  static create(repository: IAccessRepository) {
    if (!instance) {
      instance = new AccessCore(repository);
    }

    return instance;
  }

  static reset() {
    instance = null;
  }

  requireUploadAccess(auth: AuthDto | null): AuthDto {
    if (!auth || (auth.sharedLink && !auth.sharedLink.allowUpload)) {
      throw new UnauthorizedException();
    }
    return auth;
  }

  /**
   * Check if user has access to all ids, for the given permission.
   * Throws error if user does not have access to any of the ids.
   */
  async requirePermission(auth: AuthDto, permission: Permission, ids: string[] | string) {
    ids = Array.isArray(ids) ? ids : [ids];
    const allowedIds = await this.checkAccess(auth, permission, ids);
    if (!setIsEqual(new Set(ids), allowedIds)) {
      throw new BadRequestException(`Not found or no ${permission} access`);
    }
  }

  /**
   * Return ids that user has access to, for the given permission.
   * Check is done for each id, and only allowed ids are returned.
   *
   * @returns Set<string>
   */
  async checkAccess(auth: AuthDto, permission: Permission, ids: Set<string> | string[]): Promise<Set<string>> {
    const idSet = Array.isArray(ids) ? new Set(ids) : ids;
    if (idSet.size === 0) {
      return new Set();
    }

    if (auth.sharedLink) {
      return this.checkAccessSharedLink(auth.sharedLink, permission, idSet);
    }

    return this.checkAccessOther(auth, permission, idSet);
  }

  private async checkAccessSharedLink(
    sharedLink: SharedLinkEntity,
    permission: Permission,
    ids: Set<string>,
  ): Promise<Set<string>> {
    const sharedLinkId = sharedLink.id;

    switch (permission) {
      case Permission.ASSET_READ: {
        return await this.repository.asset.checkSharedLinkAccess(sharedLinkId, ids);
      }

      case Permission.ASSET_VIEW: {
        return await this.repository.asset.checkSharedLinkAccess(sharedLinkId, ids);
      }

      case Permission.ASSET_DOWNLOAD: {
        return sharedLink.allowDownload
          ? await this.repository.asset.checkSharedLinkAccess(sharedLinkId, ids)
          : new Set();
      }

      case Permission.ASSET_UPLOAD: {
        return sharedLink.allowUpload ? ids : new Set();
      }

      case Permission.ASSET_SHARE: {
        // TODO: fix this to not use sharedLink.userId for access control
        return await this.repository.asset.checkOwnerAccess(sharedLink.userId, ids);
      }

      case Permission.ALBUM_READ: {
        return await this.repository.album.checkSharedLinkAccess(sharedLinkId, ids);
      }

      case Permission.ALBUM_DOWNLOAD: {
        return sharedLink.allowDownload
          ? await this.repository.album.checkSharedLinkAccess(sharedLinkId, ids)
          : new Set();
      }

      default: {
        return new Set();
      }
    }
  }

  private async checkAccessOther(auth: AuthDto, permission: Permission, ids: Set<string>): Promise<Set<string>> {
    switch (permission) {
      // uses album id
      case Permission.ACTIVITY_CREATE: {
        return await this.repository.activity.checkCreateAccess(auth.user.id, ids);
      }

      // uses activity id
      case Permission.ACTIVITY_DELETE: {
        const isOwner = await this.repository.activity.checkOwnerAccess(auth.user.id, ids);
        const isAlbumOwner = await this.repository.activity.checkAlbumOwnerAccess(
          auth.user.id,
          setDifference(ids, isOwner),
        );
        return setUnion(isOwner, isAlbumOwner);
      }

      case Permission.ASSET_READ: {
        const isOwner = await this.repository.asset.checkOwnerAccess(auth.user.id, ids);
        const isAlbum = await this.repository.asset.checkAlbumAccess(auth.user.id, setDifference(ids, isOwner));
        const isPartner = await this.repository.asset.checkPartnerAccess(
          auth.user.id,
          setDifference(ids, isOwner, isAlbum),
        );
        return setUnion(isOwner, isAlbum, isPartner);
      }

      case Permission.ASSET_SHARE: {
        const isOwner = await this.repository.asset.checkOwnerAccess(auth.user.id, ids);
        const isPartner = await this.repository.asset.checkPartnerAccess(auth.user.id, setDifference(ids, isOwner));
        return setUnion(isOwner, isPartner);
      }

      case Permission.ASSET_VIEW: {
        const isOwner = await this.repository.asset.checkOwnerAccess(auth.user.id, ids);
        const isAlbum = await this.repository.asset.checkAlbumAccess(auth.user.id, setDifference(ids, isOwner));
        const isPartner = await this.repository.asset.checkPartnerAccess(
          auth.user.id,
          setDifference(ids, isOwner, isAlbum),
        );
        return setUnion(isOwner, isAlbum, isPartner);
      }

      case Permission.ASSET_DOWNLOAD: {
        const isOwner = await this.repository.asset.checkOwnerAccess(auth.user.id, ids);
        const isAlbum = await this.repository.asset.checkAlbumAccess(auth.user.id, setDifference(ids, isOwner));
        const isPartner = await this.repository.asset.checkPartnerAccess(
          auth.user.id,
          setDifference(ids, isOwner, isAlbum),
        );
        return setUnion(isOwner, isAlbum, isPartner);
      }

      case Permission.ASSET_UPDATE: {
        return await this.repository.asset.checkOwnerAccess(auth.user.id, ids);
      }

      case Permission.ASSET_DELETE: {
        return await this.repository.asset.checkOwnerAccess(auth.user.id, ids);
      }

      case Permission.ASSET_RESTORE: {
        return await this.repository.asset.checkOwnerAccess(auth.user.id, ids);
      }

      case Permission.ALBUM_READ: {
        const isOwner = await this.repository.album.checkOwnerAccess(auth.user.id, ids);
        const isShared = await this.repository.album.checkSharedAlbumAccess(auth.user.id, setDifference(ids, isOwner));
        return setUnion(isOwner, isShared);
      }

      case Permission.ALBUM_UPDATE: {
        return await this.repository.album.checkOwnerAccess(auth.user.id, ids);
      }

      case Permission.ALBUM_DELETE: {
        return await this.repository.album.checkOwnerAccess(auth.user.id, ids);
      }

      case Permission.ALBUM_SHARE: {
        return await this.repository.album.checkOwnerAccess(auth.user.id, ids);
      }

      case Permission.ALBUM_DOWNLOAD: {
        const isOwner = await this.repository.album.checkOwnerAccess(auth.user.id, ids);
        const isShared = await this.repository.album.checkSharedAlbumAccess(auth.user.id, setDifference(ids, isOwner));
        return setUnion(isOwner, isShared);
      }

      case Permission.ALBUM_REMOVE_ASSET: {
        return await this.repository.album.checkOwnerAccess(auth.user.id, ids);
      }

      case Permission.ASSET_UPLOAD: {
        return await this.repository.library.checkOwnerAccess(auth.user.id, ids);
      }

      case Permission.ARCHIVE_READ: {
        return ids.has(auth.user.id) ? new Set([auth.user.id]) : new Set();
      }

      case Permission.AUTH_DEVICE_DELETE: {
        return await this.repository.authDevice.checkOwnerAccess(auth.user.id, ids);
      }

      case Permission.TIMELINE_READ: {
        const isOwner = ids.has(auth.user.id) ? new Set([auth.user.id]) : new Set<string>();
        const isPartner = await this.repository.timeline.checkPartnerAccess(auth.user.id, setDifference(ids, isOwner));
        return setUnion(isOwner, isPartner);
      }

      case Permission.TIMELINE_DOWNLOAD: {
        return ids.has(auth.user.id) ? new Set([auth.user.id]) : new Set();
      }

      case Permission.MEMORY_READ: {
        return this.repository.memory.checkOwnerAccess(auth.user.id, ids);
      }

      case Permission.MEMORY_WRITE: {
        return this.repository.memory.checkOwnerAccess(auth.user.id, ids);
      }

      case Permission.MEMORY_DELETE: {
        return this.repository.memory.checkOwnerAccess(auth.user.id, ids);
      }

      case Permission.PERSON_READ: {
        return await this.repository.person.checkOwnerAccess(auth.user.id, ids);
      }

      case Permission.PERSON_WRITE: {
        return await this.repository.person.checkOwnerAccess(auth.user.id, ids);
      }

      case Permission.PERSON_MERGE: {
        return await this.repository.person.checkOwnerAccess(auth.user.id, ids);
      }

      case Permission.PERSON_CREATE: {
        return this.repository.person.checkFaceOwnerAccess(auth.user.id, ids);
      }

      case Permission.PERSON_REASSIGN: {
        return this.repository.person.checkFaceOwnerAccess(auth.user.id, ids);
      }

      case Permission.PARTNER_UPDATE: {
        return await this.repository.partner.checkUpdateAccess(auth.user.id, ids);
      }

      default: {
        return new Set();
      }
    }
  }
}