import { Injectable, NotFoundException } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository } from 'typeorm';
import { UserWork, ListStatus } from './user-work.entity';
import { WorkService } from '../work/work.service';
import { UserService } from '../user/user.service';

const XP_ADD_WORK = 10;
const XP_PROGRESS = 5;
const XP_COMPLETE = 100;
const XP_SCORE = 15;

@Injectable()
export class ListService {
  constructor(
    @InjectRepository(UserWork)
    private readonly userWorkRepo: Repository<UserWork>,
    private readonly workService: WorkService,
    private readonly userService: UserService,
  ) {}

  async getUserList(userId: number, status?: ListStatus) {
    const where: any = { userId };
    if (status) where.status = status;

    return this.userWorkRepo.find({
      where,
      relations: ['work'],
      order: { updatedAt: 'DESC' },
    });
  }

  async addToList(
    userId: number,
    anilistId: number,
    status: ListStatus,
  ): Promise<UserWork> {
    const work = await this.workService.findOrCreateFromAniList(anilistId);

    const existing = await this.userWorkRepo.findOne({
      where: { userId, workId: work.id },
    });
    if (existing) {
      existing.status = status;
      return this.userWorkRepo.save(existing);
    }

    const userWork = this.userWorkRepo.create({
      userId,
      workId: work.id,
      status,
      progress: 0,
    });
    const saved = await this.userWorkRepo.save(userWork);
    await this.userService.addXp(userId, XP_ADD_WORK);
    return saved;
  }

  async updateProgress(
    userId: number,
    userWorkId: number,
    progress: number,
  ): Promise<UserWork> {
    const uw = await this.userWorkRepo.findOne({
      where: { id: userWorkId, userId },
      relations: ['work'],
    });
    if (!uw) throw new NotFoundException('Entry not found');

    const oldProgress = uw.progress;
    uw.progress = progress;

    const total = uw.work.totalEpisodes || uw.work.totalChapters;
    if (total && progress >= total && uw.status !== ListStatus.COMPLETED) {
      uw.status = ListStatus.COMPLETED;
      uw.completedAt = new Date();
      await this.userService.addXp(userId, XP_COMPLETE);
    }

    const saved = await this.userWorkRepo.save(uw);

    if (progress > oldProgress) {
      const delta = progress - oldProgress;
      await this.userService.addXp(userId, delta * XP_PROGRESS);
    }

    return saved;
  }

  async updateStatus(
    userId: number,
    userWorkId: number,
    status: ListStatus,
  ): Promise<UserWork> {
    const uw = await this.userWorkRepo.findOne({
      where: { id: userWorkId, userId },
    });
    if (!uw) throw new NotFoundException('Entry not found');

    const wasAlreadyCompleted = uw.status === ListStatus.COMPLETED;
    uw.status = status;
    if (status === ListStatus.COMPLETED && !wasAlreadyCompleted) {
      uw.completedAt = uw.completedAt || new Date();
      await this.userService.addXp(userId, XP_COMPLETE);
    }

    return this.userWorkRepo.save(uw);
  }

  async setScore(
    userId: number,
    userWorkId: number,
    score: number,
  ): Promise<UserWork> {
    const uw = await this.userWorkRepo.findOne({
      where: { id: userWorkId, userId },
    });
    if (!uw) throw new NotFoundException('Entry not found');

    const hadScore = uw.score !== null;
    uw.score = score;
    const saved = await this.userWorkRepo.save(uw);

    if (!hadScore) {
      await this.userService.addXp(userId, XP_SCORE);
    }

    return saved;
  }

  async removeFromList(userId: number, userWorkId: number): Promise<void> {
    const uw = await this.userWorkRepo.findOne({
      where: { id: userWorkId, userId },
    });
    if (!uw) throw new NotFoundException('Entry not found');
    await this.userWorkRepo.remove(uw);
  }
}