import { assertPermission } from '../../lib/permissions.js';
import type { TokenPayload } from '../../lib/jwt.js';
import { Router } from 'express';
import { ApiError, sendOk } from '../../lib/http.js';
import { idParamSchema } from '../../lib/schemas.js';
import {
  authenticate,
  getAuthUser,
  requirePermissionOrClassDevice,
  requirePermission,
  requireAnyPermission,
} from '../../middleware/auth.js';
import { validate, validatedBody, validatedParams, validatedQuery } from '../../middleware/validate.js';
import { defineModule } from '../module.types.js';
import {
  IMPORT_KINDS,
  tableCommitSchema,
  tableFileSchema,
  timeLayoutImportSchema,
  classPlanImportSchema,
  timeLayoutQuerySchema,
  type TableCommitInput,
  type TableFileInput,
  type TimeLayoutImportInput,
  type ClassPlanImportInput,
} from './imports.schemas.js';
import { buildTemplateCsv, buildTemplateXlsx, commitTable, previewTable } from './table-import.service.js';
import { importClassPlan, previewClassPlan } from './class-plan.service.js';
import {
  deleteTimeLayout,
  importTimeLayout,
  listTimeLayouts,
  previewClassIslandTimeLayout,
} from './time-layout.service.js';

const router = Router();
router.use(authenticate());

/** 导入类型分别校验对应导入键，名单还校验管理键。 */
async function assertImportKindAllowed(
  kind: (typeof IMPORT_KINDS)[number],
  user: TokenPayload,
): Promise<void> {
  const key = {
    students: 'import:students',
    teachers: 'import:teachers',
    grades: 'grade:import',
    classTeachers: 'import:class-teachers',
    scheduleTimes: 'import:schedule',
  } as const;
  await assertPermission(user, key[kind]);
  if (kind === 'students') await assertPermission(user, 'roster:manage');
  if (kind === 'teachers') await assertPermission(user, 'teacher:manage');
}

/** 查询参数里的 kind 收敛为合法值（默认 grades，避免非法值被当成成绩悄悄写入） */
function resolveImportKind(value: unknown): (typeof IMPORT_KINDS)[number] {
  return IMPORT_KINDS.includes(value as (typeof IMPORT_KINDS)[number])
    ? (value as (typeof IMPORT_KINDS)[number])
    : 'grades';
}

/**
 * GET /api/imports/template?kind=grades|students|teachers&format=csv|xlsx - 下载导入模板
 * 成绩模板：管理员或班主任（空白模板，不含任何业务数据）；学生/教师名单模板：对应导入与管理键
 */
router.get(
  '/template',
  requireAnyPermission('import:students', 'grade:import', 'import:teachers', 'import:class-teachers'),
  async (req, res) => {
    const kind = resolveImportKind(req.query.kind);
    await assertImportKindAllowed(kind, getAuthUser(req));
    const format = req.query.format === 'xlsx' ? 'xlsx' : 'csv';
    if (format === 'xlsx') {
      const base64 = buildTemplateXlsx(kind);
      res.setHeader('content-type', 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet');
      res.setHeader('content-disposition', `attachment; filename="template-${kind}.xlsx"`);
      res.send(Buffer.from(base64, 'base64'));
      return;
    }
    sendOk(
      res,
      { kind, format, fileName: `template-${kind}.csv`, content: buildTemplateCsv(kind) },
      '模板生成成功',
    );
  },
);

/**
 * POST /api/imports/table/preview - 上传表格并预览（解析 + 必填列校验 + 建议字段映射）
 * 成绩：管理员或班主任；学生/教师名单按对应导入与管理键校验
 */
router.post(
  '/table/preview',
  requireAnyPermission('import:students', 'grade:import', 'import:teachers', 'import:class-teachers'),
  validate({ body: tableFileSchema }),
  async (req, res) => {
    const input = validatedBody<TableFileInput>(req);
    await assertImportKindAllowed(input.kind, getAuthUser(req));
    sendOk(res, previewTable(input), '表格解析成功');
  },
);

/**
 * POST /api/imports/table/commit - 执行导入（字段映射 + 写入模式 + 结果统计）
 *
 * 路由放行 ADMIN|TEACHER，真正的权限在 service 内按 kind + 班级二次校验：
 * 成绩按班级与科目收口；学生名单按管理键、导入键与班主任/全校范围校验。
 */
router.post(
  '/table/commit',
  requireAnyPermission('import:students', 'grade:import', 'import:teachers', 'import:class-teachers'),
  validate({ body: tableCommitSchema }),
  async (req, res) => {
    const input = validatedBody<TableCommitInput>(req);
    await assertImportKindAllowed(input.kind, getAuthUser(req));
    // 教师名单与班级无关；成绩/学生名单必须带班级，否则拒绝（避免写到"全局"）
    if (input.kind === 'grades' && !input.classId) {
      throw ApiError.badRequest('请先选择要导入的班级');
    }
    const result = await commitTable(getAuthUser(req), input);
    sendOk(
      res,
      result,
      `导入完成：新增 ${result.inserted} / 更新 ${result.updated} / 跳过 ${result.skipped} / 失败 ${result.failed}`,
    );
  },
);

/**
 * POST /api/imports/time-layout/preview - 预览 ClassIsland 课表时间 JSON（只解析不写库）
 * 权限与"课表管理"一致：管理员或本班班主任
 */
router.post(
  '/time-layout/preview',
  requirePermission('import:schedule', 'schedule:write'),
  validate({ body: timeLayoutImportSchema }),
  async (req, res) => {
    const input = validatedBody<TimeLayoutImportInput>(req);
    // 预览也要校验班级权限（与导入一致），避免越权探测
    const { assertCanImportSchedule } = await import('../../lib/access.js');
    await assertCanImportSchedule(getAuthUser(req), input.classId);
    sendOk(res, previewClassIslandTimeLayout(input.payload), '解析完成');
  },
);

/** GET /api/imports/time-layout?classId= - 查看该班已导入的时间配置 */
router.get(
  '/time-layout',
  requirePermissionOrClassDevice('schedule:read'),
  validate({ query: timeLayoutQuerySchema }),
  async (req, res) => {
    const { classId } = validatedQuery<{ classId: string }>(req);
    sendOk(res, await listTimeLayouts(getAuthUser(req), classId), '获取时间配置成功');
  },
);

/**
 * POST /api/imports/time-layout - 导入 ClassIsland 时间配置
 * mode=replace 覆盖 / merge 按开始时间合并；解析失败返回 400 且不修改原配置。
 */
router.post(
  '/time-layout',
  requirePermission('schedule:write', 'import:schedule'),
  validate({ body: timeLayoutImportSchema }),
  async (req, res) => {
    const result = await importTimeLayout(getAuthUser(req), validatedBody<TimeLayoutImportInput>(req));
    sendOk(
      res,
      result,
      result.mode === 'merge'
        ? `合并导入成功：合并 ${result.merged} 节 / 新增 ${result.replaced} 节`
        : `覆盖导入成功：共 ${result.replaced} 节`,
    );
  },
);

/** DELETE /api/imports/time-layout/:id - 删除某份时间配置 */
router.delete(
  '/time-layout/:id',
  requirePermission('import:schedule', 'schedule:write'),
  validate({ params: idParamSchema }),
  async (req, res) => {
    const { id } = validatedParams<{ id: string }>(req);
    await deleteTimeLayout(getAuthUser(req), id);
    sendOk(res, { id }, '时间配置已删除');
  },
);

/**
 * POST /api/imports/class-plan/preview - 预览 ClassIsland 课程表 JSON（只解析不写库）
 * 真实档案里单双周由 ClassPlan.TimeRule.WeekCountDiv / WeekCountDivTotal 表达。
 */
router.post(
  '/class-plan/preview',
  requirePermission('import:schedule', 'schedule:write'),
  validate({ body: classPlanImportSchema }),
  async (req, res) => {
    const result = await previewClassPlan(getAuthUser(req), validatedBody<ClassPlanImportInput>(req));
    sendOk(
      res,
      result,
      `解析出 ${result.entries.length} 节课（${result.subjects.length} 个科目，缺 ${result.missingSubjects.length} 个待建课程）`,
    );
  },
);

/**
 * POST /api/imports/class-plan - 导入 ClassIsland 课程表（支持单双周）
 * replace 清空后写入 / merge 按 星期+开始时间+单双周 去重；解析失败返回 400 且不改动现有课表。
 */
router.post(
  '/class-plan',
  requirePermission('import:schedule', 'schedule:write'),
  validate({ body: classPlanImportSchema }),
  async (req, res) => {
    const result = await importClassPlan(getAuthUser(req), validatedBody<ClassPlanImportInput>(req));
    sendOk(
      res,
      result,
      `导入成功：新增 ${result.created} 节 / 更新 ${result.updated} 节` +
        `${result.createdCourses.length > 0 ? `（自动补建课程：${result.createdCourses.join('、')}）` : ''}`,
    );
  },
);

export const importsModule = defineModule({
  name: 'imports',
  basePath: '/imports',
  router,
});