export interface Customer {
  id: number;
  email: string;
  // Nullable because customers who registered before these were required have
  // neither. Registration demands both from anyone new.
  first_name: string | null;
  last_name: string | null;
  email_verified: boolean;
  marketing_consent: boolean;
  favorite_alerts: boolean;
  created_at: string;
}

export interface OrderHistoryItem {
  id: number;
  processor: string;
  amount_cents: number;
  status: string;
  created_at: string;
  item_name: string;
}

async function handle<T>(res: Response): Promise<T> {
  if (!res.ok) {
    const data = await res.json().catch(() => ({}));
    throw new Error(data.error || 'Request failed');
  }
  return res.json();
}

export function registerCustomer(
  email: string,
  password: string,
  firstName: string,
  lastName: string,
  marketingConsent: boolean
): Promise<Customer> {
  return fetch('/api/customers/register', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ email, password, firstName, lastName, marketingConsent })
  }).then(res => handle<Customer>(res));
}

export function loginCustomer(email: string, password: string): Promise<Customer> {
  return fetch('/api/customers/login', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ email, password })
  }).then(res => handle<Customer>(res));
}

export function verifyEmail(token: string): Promise<{ status: string }> {
  return fetch('/api/customers/verify-email', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ token })
  }).then(res => handle<{ status: string }>(res));
}

export function logoutCustomer(): Promise<void> {
  // Not routed through handle(): logout answers 204 with no body, so parsing
  // JSON would throw on success. The failure case still has to reject — the
  // session cookie survives a failed logout, so reporting success would leave
  // the customer logged in and silently signed back in on their next reload.
  return fetch('/api/customers/logout', { method: 'POST' }).then(async (res) => {
    if (!res.ok) {
      const data = await res.json().catch(() => ({}));
      throw new Error(data.error || 'Request failed');
    }
  });
}

export function fetchMe(): Promise<Customer | null> {
  return fetch('/api/customers/me').then(res => (res.ok ? res.json() : null));
}

export function updateConsent(marketingConsent: boolean): Promise<void> {
  return fetch('/api/customers/me/consent', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ marketingConsent })
  }).then(() => undefined);
}

export function fetchMyOrders(): Promise<OrderHistoryItem[]> {
  return fetch('/api/customers/me/orders').then(res => handle<OrderHistoryItem[]>(res));
}

export function deleteMyAccount(): Promise<void> {
  return fetch('/api/customers/me', { method: 'DELETE' }).then(() => undefined);
}

export function exportMyData(): void {
  window.location.href = '/api/customers/me/export';
}

export function requestPasswordReset(email: string): Promise<{ status: string }> {
  return fetch('/api/customers/request-password-reset', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ email })
  }).then(res => handle<{ status: string }>(res));
}

export function resetPassword(token: string, password: string): Promise<Customer> {
  return fetch('/api/customers/reset-password', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ token, password })
  }).then(res => handle<Customer>(res));
}

export function updateMyName(firstName: string, lastName: string): Promise<Customer> {
  return fetch('/api/customers/me', {
    method: 'PUT',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ firstName, lastName })
  }).then(res => handle<Customer>(res));
}

export function changeMyPassword(currentPassword: string, newPassword: string): Promise<void> {
  // Answers 204 with no body, so handle() would throw parsing JSON on success.
  // The failure case still has to reject: the server's message names which of
  // the two passwords was wrong, and that is the only useful thing to show.
  return fetch('/api/customers/change-password', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ currentPassword, newPassword })
  }).then(async (res) => {
    if (!res.ok) {
      const data = await res.json().catch(() => ({}));
      throw new Error(data.error || 'Request failed');
    }
  });
}

export function changeMyEmail(currentPassword: string, email: string): Promise<Customer> {
  return fetch('/api/customers/me/email', {
    method: 'PUT',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ currentPassword, email })
  }).then(res => handle<Customer>(res));
}

export function resendVerificationEmail(): Promise<void> {
  // 204 on success, so handle() would throw parsing an empty body. The failure
  // path must still reject: the server's message distinguishes "already
  // verified" from the rate limit's "check your spam folder", and both are
  // worth showing rather than replacing with something generic.
  return fetch('/api/customers/resend-verification', { method: 'POST' }).then(async (res) => {
    if (!res.ok) {
      const data = await res.json().catch(() => ({}));
      throw new Error(data.error || 'Request failed');
    }
  });
}