import { Injectable } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { EntityManager, In, Repository } from 'typeorm';
import { Student } from '../entities/student.entity';
import { StudentProfile } from '../entities/student-profile.entity';
import { StudentEnrollment } from '../entities/student-enrollment.entity';
import { ExamScore } from '../entities/exam-score.entity';
import { LearningRecord } from '../entities/learning-record.entity';
import { ResultArchive } from '../entities/result-archive.entity';
import { Organization } from '../entities/organization.entity';
import type {
  ExamScoreImportRow,
  LearningRecordImportRow,
  StudentEnrollmentImportRow,
  StudentImportRow,
  StudentWorkbookImport,
} from './student-import';
import { getHostOrganizationId } from './students.organization';
import { addDaysToDateOnly } from '../common/china-time';

/** 学生查重/匹配的内存索引：phone 与 idNumber 各一张 Map（key 为去空白后的值）。 */
type StudentLookupIndex = {
  byPhone: Map<string, Student>;
  byIdNumber: Map<string, Student>;
};

@Injectable()
export class StudentsImportService {
  // 档案/报读/成绩等写入统一走 manager.getRepository（见下方 helpers），
  // 这里只注入 Student repo（查重、更新、开启事务）。
  constructor(
    @InjectRepository(Student) private readonly repo: Repository<Student>,
  ) {}

  async batchImport(importData: StudentWorkbookImport | StudentImportRow[]) {
    const data = this.normalizeImportData(importData);
    // 整批导入放进同一事务：查重、建学生、写档案要么全部成功，要么全部回滚。
    return this.repo.manager.transaction(async (manager) => {
      const studentRepo = manager.getRepository(Student);
      const organizationRepo = manager.getRepository(Organization);
      // 按手机号预建报读/成绩/回访行分组（手机号是导入行与学生档案之间的关联键，
      // 等价于按学生分组），避免逐学生循环内对 data.* 全量 filter。
      const enrollmentsByPhone = this.groupByPhone(data.enrollments);
      const examScoresByPhone = this.groupByPhone(data.examScores);
      const learningRecordsByPhone = this.groupByPhone(data.learningRecords);
      // 循环外按本批所有 phone/idNumber 一次性批量预取已有学生（仅两条 IN 查询），
      // 内存建索引后逐行匹配，避免逐行 findOne 的 N+1。
      const existingIndexes = await this.prefetchStudentIndexes(studentRepo, data.students);
      let imported = 0;
      let skipped = 0;
      let archiveImported = 0;
      let invalidDateSkipped = 0;
      // 本机构 id 循环外懒加载缓存一次，避免每个学生行都查询
      let hostOrganizationId: number | undefined;
      for (const row of data.students) {
        if (!row.name || !row.name.trim()) {
          skipped++;
          continue;
        }
        // 按 phone/idNumber 查重：先 phone 后 idNumber，命中即视为已存在
        if (this.matchStudentByIndexes(existingIndexes, row)) {
          skipped++;
          continue;
        }
        if (!row.organizationId && hostOrganizationId === undefined) {
          hostOrganizationId = await getHostOrganizationId(organizationRepo);
        }
        const student = await studentRepo.save(
          studentRepo.create({
            name: row.name.trim(),
            studentNo: row.studentNo?.trim() || undefined,
            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,
            supervisor: row.supervisor || undefined,
            organizationId: row.organizationId || hostOrganizationId,
          }),
        );
        // 新保存的学生同步进内存索引：本批后续相同 phone/idNumber 行视为重复跳过，
        // 保持与逐行 findOne 一致的 upsert/去重语义。
        this.indexStudent(existingIndexes, student);
        const archive = await this.importArchiveData(manager, student.id, row, {
          enrollments: enrollmentsByPhone,
          examScores: examScoresByPhone,
          learningRecords: learningRecordsByPhone,
        });
        archiveImported += archive.imported;
        invalidDateSkipped += archive.invalidDateSkipped;
        imported++;
      }
      return {
        message: `成功导入 ${imported} 名学生，导入档案相关记录 ${archiveImported} 条，跳过 ${skipped} 条（重复或空行）`,
        imported,
        archiveImported,
        skipped,
        invalidDateSkipped,
      };
    });
  }

  async matchImport(importData: StudentWorkbookImport | StudentImportRow[]) {
    const data = this.normalizeImportData(importData);
    // 整批匹配写入放进同一事务：更新学生资料与写档案要么全部成功，要么全部回滚。
    return this.repo.manager.transaction(async (manager) => {
      const studentRepo = manager.getRepository(Student);
      // 与 batchImport 一致：按手机号预建分组，避免逐学生循环内全量 filter。
      const enrollmentsByPhone = this.groupByPhone(data.enrollments);
      const examScoresByPhone = this.groupByPhone(data.examScores);
      const learningRecordsByPhone = this.groupByPhone(data.learningRecords);
      // 循环外按本批所有 phone/idNumber 一次性批量预取已有学生（仅两条 IN 查询），
      // 内存建索引后逐行匹配，避免逐行 findOne 的 N+1。
      const existingIndexes = await this.prefetchStudentIndexes(studentRepo, data.students);
      let matched = 0;
      let skipped = 0;
      let skippedNoFields = 0;
      let skippedConflict = 0;
      let archiveImported = 0;
      let invalidDateSkipped = 0;
      for (const row of data.students) {
        // 双键命中不同学生：跳过该行，避免把 idNumber 写到错误的 student 上
        if (this.hasIndexConflict(existingIndexes, row)) {
          skipped++;
          skippedConflict++;
          continue;
        }
        // Match by phone first, then idNumber
        const student = this.matchStudentByIndexes(existingIndexes, row);
        if (!student) {
          skipped++;
          continue;
        }
        const updates: Partial<
          Pick<
            Student,
            | 'name'
            | 'studentNo'
            | 'phone'
            | 'idNumber'
            | 'gender'
            | 'ethnicity'
            | 'emergencyContact'
            | 'emergencyPhone'
            | 'supervisor'
            | 'organizationId'
          >
        > = {};
        if (row.name?.trim()) updates.name = row.name.trim();
        if (row.studentNo?.trim()) updates.studentNo = row.studentNo.trim();
        // phone/idNumber 是匹配键：与命中学生一致时视为无变更（避免空 set 更新），
        // 不一致时仍允许通过另一个键命中后更新。
        if (row.phone?.trim() && row.phone.trim() !== student.phone) updates.phone = row.phone.trim();
        if (row.idNumber?.trim() && row.idNumber.trim() !== student.idNumber) updates.idNumber = row.idNumber.trim();
        if (row.gender) updates.gender = row.gender;
        if (row.ethnicity) updates.ethnicity = row.ethnicity;
        if (row.emergencyContact) updates.emergencyContact = row.emergencyContact;
        if (row.emergencyPhone) updates.emergencyPhone = row.emergencyPhone;
        if (row.supervisor) updates.supervisor = row.supervisor;
        if (row.organizationId) updates.organizationId = row.organizationId;
        // 按 phone/idNumber 命中已有学生但本行没有任何可写字段时，
        // 跳过该学生的更新（避免 TypeORM 对空 set 报错），保留匹配/去重语义。
        const hasWritableFields = Object.keys(updates).length > 0;
        const archive = await this.importArchiveData(manager, student.id, row, {
          enrollments: enrollmentsByPhone,
          examScores: examScoresByPhone,
          learningRecords: learningRecordsByPhone,
        });
        archiveImported += archive.imported;
        invalidDateSkipped += archive.invalidDateSkipped;
        if (!hasWritableFields && archive.imported === 0 && archive.invalidDateSkipped === 0) {
          // 整行无任何可写字段：计入 skipped（不抛错）
          skippedNoFields++;
          skipped++;
          continue;
        }
        if (hasWritableFields) {
          await studentRepo.update(student.id, updates);
          // 更新后的 phone/idNumber 同步进内存索引：后续行按新值仍可命中，
          // 与逐行 findOne 在同一事务内能看到本批已更新记录的语义一致。
          this.reindexStudent(existingIndexes, student, updates);
        }
        matched++;
      }
      return {
        message: `更新已有学生资料 ${matched} 人，导入档案相关记录 ${archiveImported} 条，跳过 ${skipped} 条（无匹配/无更新字段/双键冲突）`,
        matched,
        archiveImported,
        skipped,
        skippedNoFields,
        skippedConflict,
        invalidDateSkipped,
      };
    });
  }

  /**
   * 批量预取本批导入行涉及的所有 phone / idNumber 对应的已有学生：
   * 只发两条 IN 查询（phone In(...)、idNumber In(...)），内存建索引供逐行匹配，
   * 替代逐行 findOne（N+1）。某类 key 为空时跳过对应查询。
   */
  private async prefetchStudentIndexes(
    studentRepo: Repository<Student>,
    rows: StudentImportRow[],
  ): Promise<StudentLookupIndex> {
    const phones = [
      ...new Set(
        rows
          .map((row) => row.phone?.trim())
          .filter((phone): phone is string => Boolean(phone)),
      ),
    ];
    const idNumbers = [
      ...new Set(
        rows
          .map((row) => row.idNumber?.trim())
          .filter((idNumber): idNumber is string => Boolean(idNumber)),
      ),
    ];
    const [byPhoneList, byIdNumberList] = await Promise.all([
      phones.length > 0
        ? studentRepo.find({ where: { phone: In(phones) } })
        : Promise.resolve([] as Student[]),
      idNumbers.length > 0
        ? studentRepo.find({ where: { idNumber: In(idNumbers) } })
        : Promise.resolve([] as Student[]),
    ]);
    return {
      byPhone: this.buildIndex(byPhoneList, (student) => student.phone),
      byIdNumber: this.buildIndex(byIdNumberList, (student) => student.idNumber),
    };
  }

  /** 从查询结果构建 phone / idNumber → Student 的 Map（key 去空白，空值不建索引）。 */
  private buildIndex(
    students: Student[],
    keyOf: (student: Student) => string | null | undefined,
  ): Map<string, Student> {
    const index = new Map<string, Student>();
    for (const student of students) {
      const key = keyOf(student)?.trim();
      if (key) index.set(key, student);
    }
    return index;
  }

  /**
   * 双键冲突检测：同一行 phone 与 idNumber 分别命中不同的学生时，不能更新任何一个，
   * 否则会把一个学生的 idNumber 写到另一个学生身上（数据错乱）。冲突行按 skipped 处理。
   */
  private hasIndexConflict(indexes: StudentLookupIndex, row: StudentImportRow): boolean {
    const phone = row.phone?.trim();
    const idNumber = row.idNumber?.trim();
    if (!phone || !idNumber) return false;
    const byPhone = indexes.byPhone.get(phone);
    const byIdNumber = indexes.byIdNumber.get(idNumber);
    return !!byPhone && !!byIdNumber && byPhone.id !== byIdNumber.id;
  }

  /** 逐行匹配已有学生：优先 phone，未命中再按 idNumber（与 matchImport 原有语义一致）。 */
  private matchStudentByIndexes(
    indexes: StudentLookupIndex,
    row: StudentImportRow,
  ): Student | undefined {
    const phone = row.phone?.trim();
    if (phone) {
      const byPhone = indexes.byPhone.get(phone);
      if (byPhone) return byPhone;
    }
    const idNumber = row.idNumber?.trim();
    if (idNumber) {
      const byIdNumber = indexes.byIdNumber.get(idNumber);
      if (byIdNumber) return byIdNumber;
    }
    return undefined;
  }

  /** 新保存的学生同步进内存索引（batchImport 批次内去重）。 */
  private indexStudent(indexes: StudentLookupIndex, student: Student): void {
    if (student.phone) indexes.byPhone.set(student.phone.trim(), student);
    if (student.idNumber) indexes.byIdNumber.set(student.idNumber.trim(), student);
  }

  /**
   * matchImport 更新学生资料后同步内存索引：phone/idNumber 被改写时删除旧 key、
   * 注册新 key，并让内存实体与已更新值保持一致（后续行按新值仍可命中）。
   */
  private reindexStudent(
    indexes: StudentLookupIndex,
    student: Student,
    updates: Partial<Pick<Student, 'phone' | 'idNumber'>>,
  ): void {
    const oldPhone = student.phone?.trim();
    const newPhone = updates.phone?.trim();
    const oldIdNumber = student.idNumber?.trim();
    const newIdNumber = updates.idNumber?.trim();
    Object.assign(student, updates);
    if (newPhone && newPhone !== oldPhone) {
      if (oldPhone) indexes.byPhone.delete(oldPhone);
      indexes.byPhone.set(newPhone, student);
    }
    if (newIdNumber && newIdNumber !== oldIdNumber) {
      if (oldIdNumber) indexes.byIdNumber.delete(oldIdNumber);
      indexes.byIdNumber.set(newIdNumber, student);
    }
  }

  private normalizeImportData(
    importData: StudentWorkbookImport | StudentImportRow[],
  ): StudentWorkbookImport {
    if (Array.isArray(importData)) {
      return { students: importData, enrollments: [], examScores: [], learningRecords: [] };
    }
    return importData;
  }

  private normalizePhone(phone?: string) {
    return phone?.trim() || '';
  }

  private sameValue(left?: string | number | null, right?: string | number | null) {
    return String(left ?? '').trim() === String(right ?? '').trim();
  }

  /** 按手机号预建行分组（手机号去空白后作为 key，空手机号的行不参与匹配）。 */
  private groupByPhone<T extends { phone?: string }>(rows: T[]): Map<string, T[]> {
    const byPhone = new Map<string, T[]>();
    for (const row of rows) {
      const phone = this.normalizePhone(row.phone);
      if (!phone) continue;
      const list = byPhone.get(phone);
      if (list) list.push(row);
      else byPhone.set(phone, [row]);
    }
    return byPhone;
  }

  /**
   * 日期字段写入前的真实日历校验：先检查 YYYY-MM-DD 形状，
   * 再用 common/china-time 的 addDaysToDateOnly 往返判断月/日是否真实存在
   * （Date.UTC 会把溢出日期归一化，如 2024-02-31 → 2024-03-02，往返不一致即非法）。
   */
  private isValidDateOnly(value: string): boolean {
    const dateOnly = value.trim();
    if (!/^\d{4}-\d{2}-\d{2}$/.test(dateOnly)) return false;
    return addDaysToDateOnly(dateOnly, 0) === dateOnly;
  }

  private hasProfileData(row: StudentImportRow) {
    return [
      row.targetCollege,
      row.targetMajor,
      row.collegeSchool,
      row.collegeMajor,
      row.subjectDirection,
      row.grade,
      row.profileDate,
      row.notes,
    ].some((value) => value !== undefined && String(value).trim() !== '');
  }

  private hasResultData(row: StudentImportRow) {
    return [
      row.cultureFinalScore,
      row.professionalFinalScore,
      row.admissionStatus,
      row.admittedCollege,
      row.admittedMajor,
    ].some((value) => value !== undefined && String(value).trim() !== '');
  }

  private async importArchiveData(
    manager: EntityManager,
    studentId: number,
    row: StudentImportRow,
    data: {
      enrollments: Map<string, StudentEnrollmentImportRow[]>;
      examScores: Map<string, ExamScoreImportRow[]>;
      learningRecords: Map<string, LearningRecordImportRow[]>;
    },
  ): Promise<{ imported: number; invalidDateSkipped: number }> {
    const phone = this.normalizePhone(row.phone);
    let imported = 0;
    let invalidDateSkipped = 0;
    if (this.hasProfileData(row)) {
      // 非法日期不写入，跳过该字段并计数
      if (row.profileDate?.trim() && !this.isValidDateOnly(row.profileDate)) {
        invalidDateSkipped++;
      }
      await this.upsertProfileFromImport(manager, studentId, row);
      imported++;
    }
    if (this.hasResultData(row)) {
      await this.upsertResultFromImport(manager, studentId, row);
      imported++;
    }
    if (!phone) return { imported, invalidDateSkipped };

    const enrollmentRows = data.enrollments.get(phone) ?? [];
    const examRows = data.examScores.get(phone) ?? [];
    const learningRows = data.learningRecords.get(phone) ?? [];

    // 按 studentId 批量预取既有档案行，内存匹配（保持 upsert 语义），
    // 避免每个档案行单独 find 查询；新建保存后同步加入内存列表供后续行匹配。
    let existingEnrollments: StudentEnrollment[] = [];
    let existingExamScores: ExamScore[] = [];
    let existingLearningRecords: LearningRecord[] = [];
    if (enrollmentRows.length > 0) {
      existingEnrollments = await manager.getRepository(StudentEnrollment).find({
        where: { studentId },
      });
    }
    if (examRows.length > 0) {
      existingExamScores = await manager.getRepository(ExamScore).find({
        where: { studentId },
      });
    }
    if (learningRows.length > 0) {
      existingLearningRecords = await manager.getRepository(LearningRecord).find({
        where: { studentId },
      });
    }

    const enrollmentByClassName = new Map<string, StudentEnrollment>();
    for (const enrollmentRow of enrollmentRows) {
      const enrollment = await this.upsertEnrollmentFromImport(
        manager,
        studentId,
        enrollmentRow,
        existingEnrollments,
      );
      if (!enrollment) continue;
      if (enrollment.className) enrollmentByClassName.set(enrollment.className, enrollment);
      imported++;
    }
    for (const examRow of examRows) {
      // 非法日期不写入，跳过该字段并计数
      if (examRow.examDate?.trim() && !this.isValidDateOnly(examRow.examDate)) {
        invalidDateSkipped++;
      }
      if (
        await this.upsertExamScoreFromImport(
          manager,
          studentId,
          examRow,
          enrollmentByClassName,
          existingExamScores,
        )
      ) {
        imported++;
      }
    }
    for (const learningRow of learningRows) {
      // recordDate 必填：非法日期视为缺省，跳过整条并计数
      if (learningRow.recordDate?.trim() && !this.isValidDateOnly(learningRow.recordDate)) {
        invalidDateSkipped++;
        continue;
      }
      if (await this.upsertLearningRecordFromImport(manager, studentId, learningRow, existingLearningRecords)) {
        imported++;
      }
    }
    return { imported, invalidDateSkipped };
  }

  private async upsertProfileFromImport(
    manager: EntityManager,
    studentId: number,
    row: StudentImportRow,
  ) {
    const profileRepo = manager.getRepository(StudentProfile);
    const entity =
      (await profileRepo.findOne({ where: { studentId } })) ||
      profileRepo.create({ studentId });
    if (row.targetCollege?.trim()) entity.targetCollege = row.targetCollege.trim();
    if (row.targetMajor?.trim()) entity.targetMajor = row.targetMajor.trim();
    if (row.collegeSchool?.trim()) entity.collegeSchool = row.collegeSchool.trim();
    if (row.collegeMajor?.trim()) entity.collegeMajor = row.collegeMajor.trim();
    if (row.subjectDirection?.trim()) entity.subjectDirection = row.subjectDirection.trim();
    if (row.grade?.trim()) entity.grade = row.grade.trim();
    if (row.profileDate?.trim() && this.isValidDateOnly(row.profileDate)) {
      entity.profileDate = row.profileDate.trim();
    }
    if (row.notes?.trim()) entity.notes = row.notes.trim();
    await profileRepo.save(entity);
  }

  private async upsertResultFromImport(
    manager: EntityManager,
    studentId: number,
    row: StudentImportRow,
  ) {
    const resultRepo = manager.getRepository(ResultArchive);
    const entity =
      (await resultRepo.findOne({ where: { studentId } })) ||
      resultRepo.create({ studentId });
    if (row.cultureFinalScore !== undefined) entity.cultureFinalScore = row.cultureFinalScore;
    if (row.professionalFinalScore !== undefined)
      entity.professionalFinalScore = row.professionalFinalScore;
    if (row.admissionStatus?.trim()) entity.admissionStatus = row.admissionStatus.trim();
    if (row.admittedCollege?.trim()) entity.admittedCollege = row.admittedCollege.trim();
    if (row.admittedMajor?.trim()) entity.admittedMajor = row.admittedMajor.trim();
    await resultRepo.save(entity);
  }

  private async upsertEnrollmentFromImport(
    manager: EntityManager,
    studentId: number,
    row: StudentEnrollmentImportRow,
    existing: StudentEnrollment[],
  ) {
    if (!row.courseCategory?.trim() || !row.classType?.trim()) {
      return null;
    }
    const enrollmentRepo = manager.getRepository(StudentEnrollment);
    let entity = existing.find(
      (item) =>
        this.sameValue(item.courseCategory, row.courseCategory) &&
        this.sameValue(item.classType, row.classType) &&
        this.sameValue(item.className, row.className) &&
        this.sameValue(item.startDate, row.startDate),
    );
    if (!entity) {
      entity = enrollmentRepo.create({ studentId });
      // 保持 upsert 语义：后续相同行可在内存列表中命中该新建实体
      existing.push(entity);
    }
    entity.courseCategory = row.courseCategory.trim();
    entity.classType = row.classType.trim();
    if (row.className?.trim()) entity.className = row.className.trim();
    if (row.headTeacher?.trim()) entity.headTeacher = row.headTeacher.trim();
    if (row.subjectTeacher?.trim()) entity.subjectTeacher = row.subjectTeacher.trim();
    if (row.startDate?.trim()) entity.startDate = row.startDate.trim();
    if (row.endDate?.trim()) entity.endDate = row.endDate.trim();
    if (row.status?.trim()) entity.status = row.status.trim();
    else if (!entity.status) entity.status = 'active';
    return enrollmentRepo.save(entity);
  }

  private async upsertExamScoreFromImport(
    manager: EntityManager,
    studentId: number,
    row: ExamScoreImportRow,
    enrollmentByClassName: Map<string, StudentEnrollment>,
    existing: ExamScore[],
  ) {
    if (!row.examType?.trim() || !row.subject?.trim() || row.score === undefined) return false;
    const examScoreRepo = manager.getRepository(ExamScore);
    let entity = existing.find(
      (item) =>
        this.sameValue(item.examType, row.examType) &&
        this.sameValue(item.examName, row.examName) &&
        this.sameValue(item.subject, row.subject) &&
        this.sameValue(item.examDate, row.examDate),
    );
    if (!entity) {
      entity = examScoreRepo.create({ studentId });
      // 保持 upsert 语义：后续相同行可在内存列表中命中该新建实体
      existing.push(entity);
    }
    entity.examType = row.examType.trim();
    entity.subject = row.subject.trim();
    entity.score = row.score;
    if (row.examName?.trim()) entity.examName = row.examName.trim();
    if (row.classAvg !== undefined) entity.classAvg = row.classAvg;
    if (row.rank !== undefined) entity.rank = row.rank;
    if (row.examDate?.trim() && this.isValidDateOnly(row.examDate)) {
      entity.examDate = row.examDate.trim();
    }
    if (row.enrollmentName?.trim()) {
      const enrollment = enrollmentByClassName.get(row.enrollmentName.trim());
      if (enrollment) entity.enrollmentId = enrollment.id;
    }
    if (!entity.status) entity.status = 'active';
    await examScoreRepo.save(entity);
    return true;
  }

  private async upsertLearningRecordFromImport(
    manager: EntityManager,
    studentId: number,
    row: LearningRecordImportRow,
    existing: LearningRecord[],
  ) {
    if (!row.recordDate?.trim() || !row.recordType?.trim() || !row.content?.trim()) return false;
    const learningRecordRepo = manager.getRepository(LearningRecord);
    let entity = existing.find(
      (item) =>
        this.sameValue(item.recordDate, row.recordDate) &&
        this.sameValue(item.recordType, row.recordType) &&
        this.sameValue(item.content, row.content),
    );
    if (!entity) {
      entity = learningRecordRepo.create({ studentId });
      // 保持 upsert 语义：后续相同行可在内存列表中命中该新建实体
      existing.push(entity);
    }
    entity.recordDate = row.recordDate.trim();
    entity.recordType = row.recordType.trim();
    entity.content = row.content.trim();
    if (row.followUpMethod?.trim()) entity.followUpMethod = row.followUpMethod.trim();
    if (row.nextStep?.trim()) entity.nextStep = row.nextStep.trim();
    if (!entity.status) entity.status = 'active';
    await learningRecordRepo.save(entity);
    return true;
  }
}