import { Injectable } from "@nestjs/common";
import { env } from "../config/env.js";
import { logger } from "../shared/observability/logger.js";
import { BadGatewayError } from "../shared/errors/application-error.js";

export interface ViewportItem {
  key: string;
  label: string;
  route: string;
  icon: string | null;
  sortOrder: string;
  requiredPermission: string | null;
}

interface DownstreamEnvelope<T> {
  success: boolean;
  data?: T;
}

interface DashboardData {
  user: unknown;
  classes: unknown;
}

@Injectable()
export class TeacherService {
  // 聚合 IAM + classes 服务的数据
  async getDashboard(userId: string): Promise<DashboardData> {
    const [iamRes, classesRes] = await Promise.allSettled([
      fetch(`${env.IamServiceUrl}/iam/me`, {
        headers: { "x-user-id": userId },
      }),
      fetch(`${env.ClassesServiceUrl}/classes`, {
        headers: { "x-user-id": userId },
      }),
    ]);

    let user: unknown = null;
    let classes: unknown = null;

    if (iamRes.status === "fulfilled") {
      if (iamRes.value.ok) {
        user = await iamRes.value.json();
      } else {
        logger.warn(
          { status: iamRes.value.status, url: iamRes.value.url },
          "Downstream IAM service call failed",
        );
      }
    } else {
      logger.warn(
        { err: iamRes.reason, service: "iam" },
        "Downstream IAM service call rejected",
      );
    }

    if (classesRes.status === "fulfilled") {
      if (classesRes.value.ok) {
        classes = await classesRes.value.json();
      } else {
        logger.warn(
          { status: classesRes.value.status, url: classesRes.value.url },
          "Downstream classes service call failed",
        );
      }
    } else {
      logger.warn(
        { err: classesRes.reason, service: "classes" },
        "Downstream classes service call rejected",
      );
    }

    return { user, classes };
  }

  // 聚合 IAM 视口配置（L1 导航）
  async getViewports(userId: string): Promise<ViewportItem[]> {
    const res = await fetch(`${env.IamServiceUrl}/iam/viewports`, {
      headers: { "x-user-id": userId },
    });
    if (!res.ok) {
      logger.warn(
        { status: res.status, url: res.url },
        "Downstream IAM service call failed",
      );
      throw new BadGatewayError(`Downstream service returned ${res.status}`, {
        service: "iam",
        endpoint: "viewports",
        status: res.status,
      });
    }
    const json = (await res.json()) as DownstreamEnvelope<ViewportItem[]>;
    return json.data ?? [];
  }

  // 聚合班级下的考试列表（core-edu）
  async listExamsByClass(userId: string, classId: string): Promise<unknown> {
    const res = await fetch(
      `${env.CoreEduServiceUrl}/exams/class/${encodeURIComponent(classId)}`,
      { headers: { "x-user-id": userId } },
    );
    if (!res.ok) {
      logger.warn(
        { status: res.status, url: res.url },
        "Downstream core-edu service call failed",
      );
      throw new BadGatewayError(`Downstream service returned ${res.status}`, {
        service: "core-edu",
        endpoint: "exams-by-class",
        status: res.status,
      });
    }
    const json = (await res.json()) as DownstreamEnvelope<unknown>;
    return json.data ?? [];
  }

  // 聚合班级下的作业列表（core-edu）
  async listHomeworkByClass(userId: string, classId: string): Promise<unknown> {
    const res = await fetch(
      `${env.CoreEduServiceUrl}/homework/class/${encodeURIComponent(classId)}`,
      { headers: { "x-user-id": userId } },
    );
    if (!res.ok) {
      logger.warn(
        { status: res.status, url: res.url },
        "Downstream core-edu service call failed",
      );
      throw new BadGatewayError(`Downstream service returned ${res.status}`, {
        service: "core-edu",
        endpoint: "homework-by-class",
        status: res.status,
      });
    }
    const json = (await res.json()) as DownstreamEnvelope<unknown>;
    return json.data ?? [];
  }

  // 聚合考试下的成绩列表（core-edu）
  async listGradesByExam(userId: string, examId: string): Promise<unknown> {
    const res = await fetch(
      `${env.CoreEduServiceUrl}/grades/exam/${encodeURIComponent(examId)}`,
      { headers: { "x-user-id": userId } },
    );
    if (!res.ok) {
      logger.warn(
        { status: res.status, url: res.url },
        "Downstream core-edu service call failed",
      );
      throw new BadGatewayError(`Downstream service returned ${res.status}`, {
        service: "core-edu",
        endpoint: "grades-by-exam",
        status: res.status,
      });
    }
    const json = (await res.json()) as DownstreamEnvelope<unknown>;
    return json.data ?? [];
  }
}