import { Injectable, NotFoundException, BadRequestException } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository, Like, Not, In } from 'typeorm';
import { Student } from '../entities/student.entity';
import { CreateStudentDto, UpdateStudentDto } from './dto/student.dto';

@Injectable()
export class StudentsService {
  constructor(@InjectRepository(Student) private repo: Repository<Student>) {}

  async findAll(query?: { name?: string; status?: string; includeArchived?: boolean }) {
    const where: any = {};
    if (query?.name) where.name = Like(`%${query.name}%`);
    if (query?.status) {
      where.status = query.status;
    } else if (!query?.includeArchived) {
      where.status = Not('archived');
    }
    return this.repo.find({ where, order: { createdAt: 'DESC' } });
  }

  async findOne(id: number) {
    const student = await this.repo.findOne({ where: { id }, relations: ['occupancies', 'occupancies.room'] });
    if (!student) throw new NotFoundException('学生不存在');
    return student;
  }

  async create(dto: CreateStudentDto) {
    return this.repo.save(this.repo.create(dto));
  }

  async update(id: number, dto: UpdateStudentDto) {
    await this.findOne(id);
    await this.repo.update(id, dto);
    return this.repo.findOne({ where: { id } });
  }

  async remove(id: number) {
    const student = await this.findOne(id);
    if (student.status === 'archived') {
      throw new BadRequestException('该学生已归档');
    }
    // 软删除：归档而非物理删除，保留历史数据
    await this.repo.update(id, { status: 'archived' });
    return { message: '已归档（数据已保留，可随时恢复）' };
  }

  async batchRemove(ids: number[]) {
    if (!ids || ids.length === 0) throw new BadRequestException('请选择要归档的学生');
    const students = await this.repo.find({ where: { id: In(ids) } });
    const skipped: string[] = [];
    const targetIds: number[] = [];
    for (const s of students) {
      if (s.status === 'archived') skipped.push(s.name);
      else targetIds.push(s.id);
    }
    let affected = 0;
    if (targetIds.length > 0) {
      const result = await this.repo.createQueryBuilder()
        .update()
        .set({ status: 'archived' })
        .where('id IN (:...ids)', { ids: targetIds })
        .execute();
      affected = result.affected || 0;
    }
    const message = skipped.length > 0
      ? `成功归档 ${affected} 人；${skipped.length} 人已是归档状态被跳过（${skipped.slice(0, 5).join('、')}${skipped.length > 5 ? '…' : ''}）`
      : `已批量归档 ${affected} 人（数据已保留，可随时恢复）`;
    return { message, archived: affected, skipped: skipped.length };
  }

  async restore(id: number) {
    const student = await this.findOne(id);
    if (student.status !== 'archived') {
      throw new BadRequestException('该学生未被归档');
    }
    await this.repo.update(id, { status: 'active' });
    return { message: '已恢复' };
  }

  async batchImport(rows: { name: string; phone?: string; idNumber?: string; gender?: string; ethnicity?: string; emergencyContact?: string; emergencyPhone?: string; organization?: string; supervisor?: string }[]) {
    let imported = 0;
    let skipped = 0;
    for (const row of rows) {
      if (!row.name || !row.name.trim()) { skipped++; continue; }
      const exists = await this.repo.findOne({ where: { name: row.name.trim() } });
      if (exists) { skipped++; continue; }
      await this.repo.save(this.repo.create({
        name: row.name.trim(),
        phone: row.phone?.trim() || undefined,
        idNumber: row.idNumber?.trim() || undefined,
        gender: row.gender || undefined,
        ethnicity: row.ethnicity || undefined,
        emergencyContact: row.emergencyContact || undefined,
        emergencyPhone: row.emergencyPhone || undefined,
        organization: row.organization || undefined,
        supervisor: row.supervisor || undefined,
      }));
      imported++;
    }
    return { message: `成功导入 ${imported} 名学生，跳过 ${skipped} 条（重复或空行）`, imported, skipped };
  }
}