// ─────────────────────────────────────────────────────────────────────────────
//  src/lib/api/adminApi.ts
// ─────────────────────────────────────────────────────────────────────────────

import { getApiBaseUrl } from './config';

const BASE_URL = getApiBaseUrl();
const TOKEN_KEY = 'authToken';

// ─── Custom Error Class ───────────────────────────────────────────────────────

export class ApiError extends Error {
  readonly status: number;
  readonly path: string;

  constructor(
    status: number,
    message: string,
    path: string,
  ) {
    super(`[${status}] ${path} → ${message}`);
    this.status = status;
    this.path = path;
    this.name = 'ApiError';
  }
}

// ─── Shared helper ────────────────────────────────────────────────────────────

function getHeaders(): HeadersInit {
  const token = localStorage.getItem(TOKEN_KEY) ?? '';
  return {
    'Content-Type': 'application/json',
    ...(token ? { Authorization: `Bearer ${token}` } : {}),
  };
}

async function request<T>(path: string, options?: RequestInit): Promise<T | null> {
  const url = `${BASE_URL}${path}`;

  // Guard: expired token
  const token = localStorage.getItem(TOKEN_KEY);
  if (token) {
    try {
      const payload = JSON.parse(atob(token.split('.')[1]));
      if (payload?.exp && payload.exp * 1000 < Date.now()) {
        localStorage.removeItem(TOKEN_KEY);
        throw new ApiError(401, 'Session expired — please log in again', path);
      }
    } catch (e) {
      if (e instanceof ApiError) throw e;
      localStorage.removeItem(TOKEN_KEY);
    }
  }

  try {
    const res = await fetch(url, {
      ...options,
      headers: { ...getHeaders(), ...options?.headers },
    });

    if (res.status === 204) return null;

    if (!res.ok) {
      const message = await res.text().catch(() => res.statusText);
      throw new ApiError(res.status, message, path);
    }

    const text = await res.text();
    if (!text.trim()) return null;

    try {
      return JSON.parse(text) as T;
    } catch {
      return text as unknown as T;
    }
  } catch (error) {
    if (error instanceof ApiError) throw error;
    throw new Error(`Network error while calling ${path}`);
  }
}

// ─── Response Types ───────────────────────────────────────────────────────────

export interface PendingSheikhDto {
  id: number;
  name: string;
  County: string;   // API returns capital-C "County"
  specialization: string;
  experienceYears: number;
}

/**
 * Matches actual API response from:
 * GET /api/admin/dashboard/platform-analytics-and-stats
 */
export interface PlatformAnalyticsDto {
  totalUsers: number;
  usersThisMonth: number;
  pendingSheikhs: number;
  ongoingSessions: number;
  revenueThisMonth: number;
  totalRevenue: number;
  totalStudents: number;
  totalSheikhs: number;
  growth: number;
}

export interface ApiUser {
  id: number;
  fullName: string;
  email: string;
  role: 'STUDENT' | 'SHEIKH' | 'ADMIN';
  status: 'ACTIVE' | 'BLOCKED' | 'PENDING';
  createdAt: string;
  totalSessions?: number;
  rating?: number;
  earnings?: number;
  streak?: number;
}

export interface PaginatedResponse<T> {
  content: T[];
  totalElements: number;
  totalPages: number;
  size: number;
  number: number;
}

// ─── API Functions ────────────────────────────────────────────────────────────

/**
 * GET /api/admin/sheikh-approval?status=PENDING  (or UNDER_REVIEW, etc.)
 */
export interface SheikhApprovalDto {
  id: number;
  name: string;
  email: string;
  country: string;
  experienceYears: number;
  description: string;
  specializations: string;
  pricePerHour: number;
  statusOfSheikh: 'PENDING' | 'UNDER_REVIEW' | 'APPROVED' | 'REJECTED';
  interviewDateTime: string | null; // ISO: "2026-05-25T14:00:00", null if not scheduled
}

export async function fetchSheikhsByStatus(
  status: 'PENDING' | 'UNDER_REVIEW' | 'APPROVED' | 'REJECTED',
): Promise<SheikhApprovalDto[]> {
  const res = await request<SheikhApprovalDto[]>(
    `/api/admin/sheikh-approval?status=${status}`,
  );
  return Array.isArray(res) ? res : [];
}


/**
 * GET /api/admin/dashboard/platform-analytics-and-stats
 */
export async function fetchPlatformAnalytics(): Promise<PlatformAnalyticsDto> {
  const empty: PlatformAnalyticsDto = {
    totalUsers: 0, usersThisMonth: 0, pendingSheikhs: 0,
    ongoingSessions: 0, revenueThisMonth: 0, totalRevenue: 0,
    totalStudents: 0, totalSheikhs: 0, growth: 0,
  };
  try {
    const res = await request<PlatformAnalyticsDto>(
      '/api/admin/dashboard/platform-analytics-and-stats',
    );
    return res ?? empty;
  } catch (error) {
    if (error instanceof ApiError && error.status === 403) {
      throw new ApiError(403, 'Admin access required.', '/api/admin/dashboard/platform-analytics-and-stats');
    }
    return empty;
  }
}

/**
 * GET /api/admin/users  (may return 403 if endpoint not implemented yet)
 * Falls back to empty paginated response gracefully.
 */
export async function fetchAllUsers(params?: {
  role?: string;
  status?: string;
  page?: number;
  size?: number;
}): Promise<PaginatedResponse<ApiUser>> {
  const empty: PaginatedResponse<ApiUser> = {
    content: [], totalElements: 0, totalPages: 0, size: 0, number: 0,
  };

  const queryParams = new URLSearchParams();
  if (params?.role) queryParams.append('role', params.role);
  if (params?.status) queryParams.append('status', params.status);
  if (params?.page !== undefined) queryParams.append('page', String(params.page));
  if (params?.size !== undefined) queryParams.append('size', String(params.size));
  const query = queryParams.toString() ? `?${queryParams.toString()}` : '';

  try {
    const res = await request<PaginatedResponse<ApiUser>>(`/api/admin/users${query}`);
    if (!res) return empty;
    // Handle both paginated { content: [] } and plain array responses
    if (Array.isArray(res)) {
      return { content: res as ApiUser[], totalElements: (res as ApiUser[]).length, totalPages: 1, size: (res as ApiUser[]).length, number: 0 };
    }
    return res;
  } catch (error) {
    // 403 → endpoint not available for this role/token, return empty silently
    if (error instanceof ApiError && (error.status === 403 || error.status === 404)) {
      return empty;
    }
    throw error;
  }
}

/**
 * POST /api/admin/users/:id/block  or  /api/admin/users/:id/unblock
 */
export async function toggleUserBlock(
  userId: number,
  block: boolean,
): Promise<{ success: boolean; message: string }> {
  const action = block ? 'block' : 'unblock';
  try {
    const res = await request<{ success: boolean; message: string }>(
      `/api/admin/users/${userId}/${action}`,
      { method: 'POST' },
    );
    return res ?? { success: true, message: 'Done' };
  } catch (error) {
    if (error instanceof ApiError) throw error;
    throw new Error(`Failed to ${action} user`);
  }
}

/**
 * DELETE /api/admin/users/:id
 */
export async function deleteUser(
  userId: number,
): Promise<{ success: boolean; message: string }> {
  try {
    const res = await request<{ success: boolean; message: string }>(
      `/api/admin/user-management/users/${userId}`,
      { method: 'DELETE' },
    );
    return res ?? { success: true, message: 'Deleted' };
  } catch (error) {
    if (error instanceof ApiError) throw error;
    throw new Error('Failed to delete user');
  }
}

/**
 * GET /api/admin/dashboard/pending-sheikhs  (used by AdminDashboard)
 */
export async function fetchPendingSheikhs(): Promise<PendingSheikhDto[]> {
  const res = await request<PendingSheikhDto[]>('/api/admin/dashboard/pending-sheikhs');
  return Array.isArray(res) ? res : [];
}

export async function approveSheikh(
  sheikhId: number,
): Promise<void> {
  await request<void>(
    `/api/admin/sheikh-approval/${sheikhId}/approve`,
    { method: 'PATCH' },
  );
}

export async function rejectSheikh(
  sheikhId: number,
  reason: string,
): Promise<void> {
  await request<void>(
    `/api/admin/sheikh-approval/${sheikhId}/reject`,
    { method: 'PATCH', body: JSON.stringify({ rejectionReason: reason }) },
  );
}

/**
 * POST /api/admin/sheikh-approval/:id/schedule-interview
 * Schedules an interview and moves the sheikh status to UNDER_REVIEW.
 */
export async function scheduleInterview(
  sheikhId: number,
  interviewDate: string, // "YYYY-MM-DD"
  interviewTime: string, // "HH:mm"
  optionalMessage?: string,
): Promise<{ success: boolean; message: string }> {
  const res = await request<{ success: boolean; message: string }>(
    `/api/admin/sheikh-approval/${sheikhId}/schedule-interview`,
    { method: 'POST', body: JSON.stringify({ interviewDate, interviewTime, optionalMessage: optionalMessage ?? '' }) },
  );
  return res ?? { success: true, message: 'Interview scheduled' };
}

// eslint-disable-next-line @typescript-eslint/no-explicit-any
export async function fetchSheikhDetails(sheikhId: number): Promise<any> {
  try {
    return await request(`/api/admin/sheikhs/${sheikhId}`);
  } catch {
    return null;
  }
}

export async function saveInterviewNotes(
  sheikhId: string | number | undefined,
  notes: string,
): Promise<void> {
  if (!sheikhId) return;
  await request<void>(
    `/api/admin/sheikh-approval/${sheikhId}/notes`,
    { method: 'PATCH', body: JSON.stringify({ notes }) },
  );
}

// ─── Dashboard loader ─────────────────────────────────────────────────────────

export interface AdminDashboardData {
  pendingSheikhs: PendingSheikhDto[];
  platformAnalytics: PlatformAnalyticsDto;
}

export async function fetchAdminDashboardData(): Promise<{
  data: Partial<AdminDashboardData>;
  errors: Record<string, string>;
}> {
  const [sheikhsRes, analyticsRes] = await Promise.allSettled([
    fetchPendingSheikhs(),
    fetchPlatformAnalytics(),
  ]);

  const data: Partial<AdminDashboardData> = {};
  const errors: Record<string, string> = {};

  data.pendingSheikhs =
    sheikhsRes.status === 'fulfilled'
      ? sheikhsRes.value
      : (errors.pendingSheikhs = sheikhsRes.reason?.message ?? 'Error', []);

  data.platformAnalytics =
    analyticsRes.status === 'fulfilled'
      ? analyticsRes.value
      : (errors.platformAnalytics = analyticsRes.reason?.message ?? 'Error',
      {
        totalUsers: 0, usersThisMonth: 0, pendingSheikhs: 0, ongoingSessions: 0,
        revenueThisMonth: 0, totalRevenue: 0, totalStudents: 0, totalSheikhs: 0, growth: 0
      });

  return { data, errors };
}

const adminApi = {
  fetchPendingSheikhs, fetchSheikhsByStatus, fetchPlatformAnalytics, fetchAdminDashboardData,
  approveSheikh, rejectSheikh, scheduleInterview, fetchSheikhDetails, saveInterviewNotes,
  fetchAllUsers, toggleUserBlock, deleteUser,
};

export default adminApi;