import { Injectable, InternalServerErrorException, Logger } from "@nestjs/common";

import { UserGroup } from "../../users/entities/user-group.entity";
import { User } from "../../users/entities/user.entity";
import { UsersService } from "../../users/providers/users.service";
import { IReferralStrategy } from "../interfaces/referral-strategy";

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

  constructor(private readonly usersService: UsersService) {}

  async assignAdmin(group: UserGroup): Promise<User> {
    try {
      const { users: admins } = await this.usersService.getUsersByGroup(group.id);

      if (!admins.length) {
        this.logger.warn(`No admins found in Group: ${group.name}, falling back to super admin`);
        //fall back
        const superAdmin = await this.usersService.getSuperAdmin();
        if (!superAdmin) throw new InternalServerErrorException("No super admin found as fallback");

        return superAdmin;
      }

      // return the one with the fewest tickets
      return admins.reduce((prev, curr) => ((prev.tickets?.length || 0) < (curr.tickets?.length || 0) ? prev : curr));
      //
    } catch (error: unknown) {
      this.logger.error(`Error assigning admin for group ${group.name}: ${error instanceof Error ? error.message : "Unknown error"}`);
      // If any error occurs, try to get a super admin as last resort
      const superAdmin = await this.usersService.getSuperAdmin();
      if (!superAdmin) throw new InternalServerErrorException("No super admin found as fallback");

      return superAdmin;
    }
  }
}