const BASE = '/api/v1';

function getToken(): string | null {
  return localStorage.getItem('token');
}

class ApiError extends Error {
  status: number;
  data: any;
  constructor(message: string, status: number, data: any) {
    super(message);
    this.status = status;
    this.data = data;
  }
}

async function request<T>(method: string, path: string, body?: unknown): Promise<T> {
  const headers: Record<string, string> = { 'Content-Type': 'application/json' };
  const token = getToken();
  if (token) headers['Authorization'] = `Bearer ${token}`;

  const res = await fetch(`${BASE}${path}`, {
    method,
    headers,
    body: body !== undefined ? JSON.stringify(body) : undefined,
  });

  if (res.status === 204) return undefined as T;
  const data = await res.json();
  if (!res.ok) throw new ApiError(data.error || data.message || 'Request failed', res.status, data);
  return data as T;
}

export { ApiError };

export const api = {
  // Setup
  getSetupStatus: () =>
    request<{ needs_setup: boolean }>('GET', '/setup/status'),
  createSetupAdmin: (data: { name: string; email: string; password: string }) =>
    request<{ token: string }>('POST', '/setup/admin', data),

  // Auth
  login: (email: string, password: string) =>
    request<{ token: string }>('POST', '/auth/login', { email, password }),
  activate: (token: string, password: string) =>
    request<Volunteer>('POST', '/auth/activate', { token, password }),

  // Volunteers
  createVolunteer: (data: CreateVolunteerInput) =>
    request<AdminVolunteer>('POST', '/volunteers', data),
  listVolunteers: () => request<Volunteer[] | AdminVolunteer[]>('GET', '/volunteers'),
  getVolunteer: (id: number) => request<Volunteer | AdminVolunteer>('GET', `/volunteers/${id}`),
  updateVolunteer: (id: number, data: Partial<UpdateVolunteerInput>) =>
    request<Volunteer>('PUT', `/volunteers/${id}`, data),
  resendInvite: (id: number) =>
    request<{ invite_token: string }>('POST', `/volunteers/${id}/invite`, {}),

  // Shift templates
  listShiftTemplates: () => request<ShiftTemplate[]>('GET', '/shift-templates'),
  createShiftTemplate: (data: CreateShiftTemplateInput) =>
    request<ShiftTemplate>('POST', '/shift-templates', data),
  updateShiftTemplate: (id: number, data: Partial<CreateShiftTemplateInput>) =>
    request<ShiftTemplate>('PUT', `/shift-templates/${id}`, data),
  deleteShiftTemplate: (id: number) => request<void>('DELETE', `/shift-templates/${id}`),

  // Shift instances
  listShifts: (year: number, month: number) =>
    request<ShiftInstance[]>('GET', `/shifts?year=${year}&month=${month}`),
  generateShifts: (year: number, month: number) =>
    request<ShiftInstance[]>('POST', '/shifts/generate', { year, month }),
  publishShifts: (year: number, month: number) =>
    request<{ year: number; month: number }>('POST', '/shifts/publish', { year, month }),
  unpublishShifts: (year: number, month: number) =>
    request<{ year: number; month: number }>('POST', '/shifts/unpublish', { year, month }),
  updateShift: (id: number, data: UpdateShiftInput) =>
    request<ShiftInstance>('PUT', `/shifts/${id}`, data),
  confirmShift: (id: number) => request<void>('POST', `/shifts/${id}/confirm`, {}),

  // Time off
  listTimeOff: () => request<TimeOffRequest[]>('GET', '/timeoff'),
  createTimeOff: (data: CreateTimeOffInput & { volunteer_id?: number; confirm_conflicts?: boolean }) =>
    request<TimeOffRequest | TimeOffConflictResponse>('POST', '/timeoff', data),
  updateTimeOff: (id: number, data: { starts_at: string; ends_at: string; reason?: string }) =>
    request<TimeOffRequest>('PUT', `/timeoff/${id}`, data),
  deleteTimeOff: (id: number) =>
    request<{ deleted: boolean; restored_shifts: ConflictingShift[] }>('DELETE', `/timeoff/${id}`),
  reviewTimeOff: (id: number, status: 'approved' | 'rejected') =>
    request<TimeOffRequest>('PUT', `/timeoff/${id}/review`, { status }),
  getRemovedShifts: (id: number) =>
    request<ConflictingShift[]>('GET', `/timeoff/${id}/shifts`),

  // Check-in / out
  checkIn: (schedule_id?: number, notes?: string) =>
    request<CheckIn>('POST', '/checkin', { schedule_id, notes }),
  checkOut: (notes?: string) => request<CheckIn>('POST', '/checkout', { notes }),
  getHistory: () => request<CheckIn[]>('GET', '/checkin/history'),

  // Notifications
  listNotifications: () => request<Notification[]>('GET', '/notifications'),
  markRead: (id: number) => request<Notification>('PUT', `/notifications/${id}/read`, {}),
};

export interface Volunteer {
  id: number;
  name: string;
  email: string;
  role: 'admin' | 'volunteer';
  active: boolean;
  is_trainee: boolean;
  phone?: string;
  operational_roles: string;
  notification_preference: string;
  last_login?: string;
  completed_shifts: number;
  created_at: string;
  updated_at: string;
}

export interface AdminVolunteer extends Volunteer {
  admin_notes?: string;
  invite_token?: string;
}

export interface CreateVolunteerInput {
  name: string;
  email: string;
  role?: 'admin' | 'volunteer';
  is_trainee?: boolean;
  phone?: string;
  operational_roles?: string;
}

export interface UpdateVolunteerInput {
  name?: string;
  email?: string;
  phone?: string;
  role?: 'admin' | 'volunteer';
  active?: boolean;
  is_trainee?: boolean;
  operational_roles?: string;
  notification_preference?: string;
  admin_notes?: string;
}

export interface TemplateRole {
  id?: number;
  template_id?: number;
  role_name: string;
  count: number;
}

export interface ShiftTemplate {
  id: number;
  name: string;
  day_of_week: number; // 0=Sun, 1=Mon, ..., 6=Sat
  start_time: string;
  end_time: string;
  min_capacity: number;
  max_capacity: number;
  roles: TemplateRole[];
  volunteer_ids: number[];
  created_at: string;
  updated_at: string;
}

export interface CreateShiftTemplateInput {
  name: string;
  day_of_week: number;
  start_time: string;
  end_time: string;
  min_capacity: number;
  max_capacity: number;
  roles?: TemplateRole[];
  volunteer_ids?: number[];
}

export interface InstanceVolunteer {
  instance_id: number;
  volunteer_id: number;
  name: string;
  confirmed: boolean;
  confirmed_at?: string;
}

export interface ShiftInstance {
  id: number;
  template_id?: number;
  name: string;
  date: string; // "YYYY-MM-DD"
  start_time: string;
  end_time: string;
  min_capacity: number;
  max_capacity: number;
  status: 'draft' | 'published';
  year: number;
  month: number;
  volunteers: InstanceVolunteer[];
  created_at: string;
  updated_at: string;
}

export interface UpdateShiftInput {
  volunteer_ids?: number[];
  min_capacity?: number;
  max_capacity?: number;
}

export interface TimeOffRequest {
  id: number;
  volunteer_id: number;
  starts_at: string;
  ends_at: string;
  reason?: string;
  status: 'pending' | 'approved' | 'rejected';
  reviewed_by?: number;
  reviewed_at?: string;
  created_at: string;
  updated_at: string;
}

export interface CreateTimeOffInput {
  starts_at: string;
  ends_at: string;
  reason?: string;
}

export interface ConflictingShift {
  instance_id: number;
  name: string;
  date: string;
  start_time: string;
  end_time: string;
}

export interface TimeOffConflictResponse {
  message: string;
  conflicts: ConflictingShift[];
}

export interface CheckIn {
  id: number;
  volunteer_id: number;
  schedule_id?: number;
  checked_in_at: string;
  checked_out_at?: string;
  notes?: string;
}

export interface Notification {
  id: number;
  volunteer_id: number;
  message: string;
  is_read: boolean;
  created_at: string;
}

export const OPERATIONAL_ROLES = [
  'Behaviour Team',
  'Dog Log Monitor',
  'Dog Shelter Volunteer',
  'Trainee',
  'Floater',
] as const;