import { Injectable } from '@nestjs/common';
import { PrismaService } from '../../infrastructure/database/prisma.service';

@Injectable()
export class LearningSessionRepository {
  constructor(private readonly prisma: PrismaService) {}

  async create(userId: string, dto: {
    knowledgeItemId?: string;
    knowledgeBaseId?: string;
    mode?: string;
  }) {
    return this.prisma.learningSession.create({
      data: {
        userId,
        knowledgeItemId: dto.knowledgeItemId ?? null,
        knowledgeBaseId: dto.knowledgeBaseId ?? null,
        mode: dto.mode ?? 'reading',
        status: 'active',
        startedAt: new Date(),
      },
    });
  }

  async end(id: string) {
    const session = await this.prisma.learningSession.findUnique({ where: { id } });
    if (!session) return undefined;

    return this.prisma.learningSession.update({
      where: { id },
      data: {
        status: 'completed',
        endedAt: new Date(),
        durationSeconds: Math.floor(
          (Date.now() - session.startedAt.getTime()) / 1000,
        ),
      },
    });
  }

  async findByUserId(userId: string, pagination?: { page?: number; limit?: number }) {
    const page = pagination?.page ?? 1;
    const limit = pagination?.limit ?? 20;
    return this.prisma.learningSession.findMany({
      where: { userId },
      orderBy: { startedAt: 'desc' },
      skip: (page - 1) * limit,
      take: limit,
    });
  }
}