// ─────────────────────────────────────────────────────────────────────────────
//  src/lib/api/studentsapi.ts
//  API layer for My Students page — matches actual backend endpoints
// ─────────────────────────────────────────────────────────────────────────────

import { getApiBaseUrl } from './config';

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

// ─── Shared helpers ───────────────────────────────────────────────────────────

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

export class StudentsApiError extends Error {
  readonly status: number;

  constructor(status: number, message: string) {
    super(message);
    this.status = status;
    this.name = 'StudentsApiError';
  }
}

async function request<T>(path: string, options?: RequestInit): Promise<T> {
  const res = await fetch(`${BASE_URL}${path}`, {
    ...options,
    headers: { ...getHeaders(), ...options?.headers },
  });

  // 204 No Content → return empty array gracefully
  if (res.status === 204) {
    return [] as unknown as T;
  }

  if (!res.ok) {
    const message = await res.text().catch(() => res.statusText);
    throw new StudentsApiError(
      res.status,
      `[${res.status}] ${path} → ${message}`,
    );
  }

  const text = await res.text();
  if (!text) return [] as unknown as T;

  try {
    return JSON.parse(text) as T;
  } catch {
    return text as unknown as T;
  }
}

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

export interface Session {
  id: string;
  date: string;
  duration: number;
  status: 'completed' | 'cancelled' | 'upcoming';
  rating?: number;
  feedback?: string;
  price: number;
  topic: string;
}

export interface Student {
  id: string;
  name: string;
  email: string;
  phone?: string;
  location?: string;
  joinedDate: string;
  totalSessions: number;
  completedSessions: number;
  cancelledSessions: number;
  totalMinutes: number;
  totalSpent: number;
  averageRating: number;
  lastSession: string;
  currentStreak: number;
  progress: number;
  level: string;
  goals: string[];
  sessionHistory?: Session[];
}

export interface StudentsStats {
  totalStudents: number;
  activeLast7Days: number;
  totalSessions: number;
  averageRating: number;
}

// ─── Raw-to-typed normalizer ──────────────────────────────────────────────────
// Maps any backend field naming to our Student shape safely

// eslint-disable-next-line @typescript-eslint/no-explicit-any
function normalizeStudent(raw: any): Student {
  return {
    id: String(
      raw.id ?? raw.studentId ?? raw.userId ?? '',
    ),
    name:
      raw.name ??
      raw.fullName ??
      raw.studentName ??
      '',
    email: raw.email ?? raw.emailAddress ?? '',
    phone: raw.phone ?? raw.phoneNumber ?? undefined,
    location: raw.location ?? raw.city ?? undefined,
    joinedDate:
      raw.joinedDate ?? raw.createdAt ?? new Date().toISOString(),
    totalSessions: raw.totalSessions ?? raw.sessionsCount ?? 0,
    completedSessions: raw.completedSessions ?? raw.completed ?? 0,
    cancelledSessions: raw.cancelledSessions ?? raw.cancelled ?? 0,
    totalMinutes: raw.totalMinutes ?? raw.totalTime ?? 0,
    totalSpent:
      raw.totalSpent ?? raw.totalPaid ?? raw.totalEarnings ?? 0,
    averageRating: raw.averageRating ?? raw.rating ?? 0,
    lastSession:
      raw.lastSession ??
      raw.lastSessionDate ??
      new Date().toISOString(),
    currentStreak: raw.currentStreak ?? raw.streak ?? 0,
    progress: raw.progress ?? raw.progressPercent ?? 0,
    level: raw.level ?? raw.studentLevel ?? 'Beginner',
    goals: Array.isArray(raw.goals) ? raw.goals : [],
    sessionHistory: Array.isArray(raw.sessionHistory)
      ? raw.sessionHistory
      : undefined,
  };
}

// eslint-disable-next-line @typescript-eslint/no-explicit-any
async function requestStudents(path: string): Promise<Student[]> {
  const raw = await request<unknown>(path);
  if (!Array.isArray(raw)) return [];
  return raw.map(normalizeStudent);
}

// ─── API Functions — exact endpoints from backend docs ────────────────────────

/**
 * GET /api/sheikh/my-students
 * All students the sheikh has had sessions with
 */
export function getAllStudents(): Promise<Student[]> {
  return requestStudents('/api/sheikh/my-students');
}

/**
 * GET /api/sheikh/my-students/active-last-7-days
 * Students active in the past 7 days
 */
export function getActiveStudents(): Promise<Student[]> {
  return requestStudents('/api/sheikh/my-students/active-last-7-days');
}

/**
 * GET /api/sheikh/my-students/top-students
 * Top performing students
 */
export function getTopStudents(): Promise<Student[]> {
  return requestStudents('/api/sheikh/my-students/top-students');
}

/**
 * GET /api/sheikh/my-students/search?keyword=query
 * Search students by keyword
 */
export function searchStudents(keyword: string): Promise<Student[]> {
  return requestStudents(
    `/api/sheikh/my-students/search?keyword=${encodeURIComponent(keyword)}`,
  );
}

/**
 * GET /api/sheikh/my-students/View-Student?id=id
 * Detailed info for a specific student
 */
export async function getStudentDetails(id: number): Promise<Student> {
  // eslint-disable-next-line @typescript-eslint/no-explicit-any
  const raw = await request<any>(
    `/api/sheikh/my-students/View-Student?id=${id}`,
  );
  return normalizeStudent(raw);
}

/**
 * GET /api/sheikh/my-students/stats
 * Aggregate statistics for all the sheikh's students
 */
export async function getStudentsStats(): Promise<StudentsStats> {
  // eslint-disable-next-line @typescript-eslint/no-explicit-any
  const raw = await request<any>('/api/sheikh/my-students/stats');
  return {
    totalStudents:
      raw.totalStudents ?? raw.total ?? 0,
    activeLast7Days:
      raw.activeLast7Days ?? raw.activeStudents ?? raw.active ?? 0,
    totalSessions:
      raw.totalSessions ?? raw.sessions ?? 0,
    averageRating:
      raw.averageRating ?? raw.avgRating ?? raw.rating ?? 0,
  };
}