import type {
  AuthResponse,
  UserLogin,
  UserRegister,
  User,
  Subject,
  SubjectCreate,
  SubjectUpdate,
  Grade,
  GradeCreate,
  GradeUpdate,
  ReportPeriod,
  ReportPeriodCreate,
  ReportPeriodUpdate,
  TeacherGrade,
  TeacherGradeCreate,
  TeacherGradeUpdate,
} from "~/types/api";

const API_BASE_URL = import.meta.env.VITE_API_URL || "http://localhost:8000/api";

class ApiClient {
  private getHeaders(includeAuth: boolean = false): HeadersInit {
    const headers: HeadersInit = {
      "Content-Type": "application/json",
    };

    if (includeAuth) {
      const token = localStorage.getItem("access_token");
      if (token) {
        headers["Authorization"] = `Bearer ${token}`;
      }
    }

    return headers;
  }

  private async handleResponse<T>(response: Response): Promise<T> {
    if (!response.ok) {
      const error = await response.json().catch(() => ({ detail: "An error occurred" }));
      throw new Error(error.detail || `HTTP ${response.status}`);
    }

    if (response.status === 204) {
      return undefined as T;
    }

    return response.json();
  }

  // Auth endpoints
  async register(data: UserRegister): Promise<AuthResponse> {
    const response = await fetch(`${API_BASE_URL}/auth/register`, {
      method: "POST",
      headers: this.getHeaders(),
      body: JSON.stringify(data),
    });
    const result = await this.handleResponse<AuthResponse>(response);
    localStorage.setItem("access_token", result.access_token);
    return result;
  }

  async login(data: UserLogin): Promise<AuthResponse> {
    const response = await fetch(`${API_BASE_URL}/auth/login`, {
      method: "POST",
      headers: this.getHeaders(),
      body: JSON.stringify(data),
    });
    const result = await this.handleResponse<AuthResponse>(response);
    localStorage.setItem("access_token", result.access_token);
    return result;
  }

  async getMe(): Promise<User> {
    const response = await fetch(`${API_BASE_URL}/auth/me`, {
      headers: this.getHeaders(true),
    });
    return this.handleResponse<User>(response);
  }

  logout(): void {
    localStorage.removeItem("access_token");
  }

  isAuthenticated(): boolean {
    return !!localStorage.getItem("access_token");
  }

  // Subject endpoints
  async getSubjects(): Promise<Subject[]> {
    const response = await fetch(`${API_BASE_URL}/subjects`, {
      headers: this.getHeaders(true),
    });
    return this.handleResponse<Subject[]>(response);
  }

  async getSubject(id: string): Promise<Subject> {
    const response = await fetch(`${API_BASE_URL}/subjects/${id}`, {
      headers: this.getHeaders(true),
    });
    return this.handleResponse<Subject>(response);
  }

  async createSubject(data: SubjectCreate): Promise<Subject> {
    const response = await fetch(`${API_BASE_URL}/subjects`, {
      method: "POST",
      headers: this.getHeaders(true),
      body: JSON.stringify(data),
    });
    return this.handleResponse<Subject>(response);
  }

  async updateSubject(id: string, data: SubjectUpdate): Promise<Subject> {
    const response = await fetch(`${API_BASE_URL}/subjects/${id}`, {
      method: "PUT",
      headers: this.getHeaders(true),
      body: JSON.stringify(data),
    });
    return this.handleResponse<Subject>(response);
  }

  async deleteSubject(id: string): Promise<void> {
    const response = await fetch(`${API_BASE_URL}/subjects/${id}`, {
      method: "DELETE",
      headers: this.getHeaders(true),
    });
    return this.handleResponse<void>(response);
  }

  // Grade endpoints
  async getGrades(subjectId?: string): Promise<Grade[]> {
    const url = subjectId
      ? `${API_BASE_URL}/grades?subject_id=${subjectId}`
      : `${API_BASE_URL}/grades`;
    const response = await fetch(url, {
      headers: this.getHeaders(true),
    });
    return this.handleResponse<Grade[]>(response);
  }

  async getGrade(id: string): Promise<Grade> {
    const response = await fetch(`${API_BASE_URL}/grades/${id}`, {
      headers: this.getHeaders(true),
    });
    return this.handleResponse<Grade>(response);
  }

  async createGrade(data: GradeCreate): Promise<Grade> {
    const response = await fetch(`${API_BASE_URL}/grades`, {
      method: "POST",
      headers: this.getHeaders(true),
      body: JSON.stringify(data),
    });
    return this.handleResponse<Grade>(response);
  }

  async updateGrade(id: string, data: GradeUpdate): Promise<Grade> {
    const response = await fetch(`${API_BASE_URL}/grades/${id}`, {
      method: "PUT",
      headers: this.getHeaders(true),
      body: JSON.stringify(data),
    });
    return this.handleResponse<Grade>(response);
  }

  async deleteGrade(id: string): Promise<void> {
    const response = await fetch(`${API_BASE_URL}/grades/${id}`, {
      method: "DELETE",
      headers: this.getHeaders(true),
    });
    return this.handleResponse<void>(response);
  }

  // Report Period endpoints
  async getPeriods(): Promise<ReportPeriod[]> {
    const response = await fetch(`${API_BASE_URL}/periods`, {
      headers: this.getHeaders(true),
    });
    return this.handleResponse<ReportPeriod[]>(response);
  }

  async getPeriod(id: string): Promise<ReportPeriod> {
    const response = await fetch(`${API_BASE_URL}/periods/${id}`, {
      headers: this.getHeaders(true),
    });
    return this.handleResponse<ReportPeriod>(response);
  }

  async createPeriod(data: ReportPeriodCreate): Promise<ReportPeriod> {
    const response = await fetch(`${API_BASE_URL}/periods`, {
      method: "POST",
      headers: this.getHeaders(true),
      body: JSON.stringify(data),
    });
    return this.handleResponse<ReportPeriod>(response);
  }

  async updatePeriod(id: string, data: ReportPeriodUpdate): Promise<ReportPeriod> {
    const response = await fetch(`${API_BASE_URL}/periods/${id}`, {
      method: "PUT",
      headers: this.getHeaders(true),
      body: JSON.stringify(data),
    });
    return this.handleResponse<ReportPeriod>(response);
  }

  async deletePeriod(id: string): Promise<void> {
    const response = await fetch(`${API_BASE_URL}/periods/${id}`, {
      method: "DELETE",
      headers: this.getHeaders(true),
    });
    return this.handleResponse<void>(response);
  }

  // Teacher Grade endpoints
  async getTeacherGrades(subjectId?: string, periodId?: string): Promise<TeacherGrade[]> {
    const params = new URLSearchParams();
    if (subjectId) params.append("subject_id", subjectId);
    if (periodId) params.append("period_id", periodId);
    const url = `${API_BASE_URL}/teacher-grades${params.toString() ? `?${params.toString()}` : ""}`;
    
    const response = await fetch(url, {
      headers: this.getHeaders(true),
    });
    return this.handleResponse<TeacherGrade[]>(response);
  }

  async getTeacherGrade(id: string): Promise<TeacherGrade> {
    const response = await fetch(`${API_BASE_URL}/teacher-grades/${id}`, {
      headers: this.getHeaders(true),
    });
    return this.handleResponse<TeacherGrade>(response);
  }

  async createTeacherGrade(data: TeacherGradeCreate): Promise<TeacherGrade> {
    const response = await fetch(`${API_BASE_URL}/teacher-grades`, {
      method: "POST",
      headers: this.getHeaders(true),
      body: JSON.stringify(data),
    });
    return this.handleResponse<TeacherGrade>(response);
  }

  async deleteTeacherGrade(id: string): Promise<void> {
    const response = await fetch(`${API_BASE_URL}/teacher-grades/${id}`, {
      method: "DELETE",
      headers: this.getHeaders(true),
    });
    return this.handleResponse<void>(response);
  }

  // Export endpoints
  async exportGradesCSV(periodId?: string): Promise<void> {
    const url = periodId
      ? `${API_BASE_URL}/export/grades?period_id=${periodId}`
      : `${API_BASE_URL}/export/grades`;
    
    const response = await fetch(url, {
      headers: this.getHeaders(true),
    });

    if (!response.ok) {
      throw new Error("Failed to export grades");
    }

    // Create a blob from the response and trigger download
    const blob = await response.blob();
    const downloadUrl = window.URL.createObjectURL(blob);
    const a = document.createElement("a");
    a.href = downloadUrl;
    
    // Extract filename from Content-Disposition header or use default
    const contentDisposition = response.headers.get("Content-Disposition");
    const filename = contentDisposition
      ? contentDisposition.split("filename=")[1]?.replace(/"/g, "")
      : "grades_export.csv";
    
    a.download = filename;
    document.body.appendChild(a);
    a.click();
    document.body.removeChild(a);
    window.URL.revokeObjectURL(downloadUrl);
  }
}

export const api = new ApiClient();