// Notification store (Supabase-backed)

import { supabase } from './supabase';

export type NotificationType = 'approval_result' | 'new_request' | 'status_change' | 'system';

export interface Notification {
  id: string;
  userId: string;
  type: NotificationType;
  title: string;
  body: string;
  linkTo?: string;
  relatedApprovalId?: string;
  read: boolean;
  createdAt: string;
}

// --- Mapping helpers ---

function dbToNotif(row: Record<string, unknown>): Notification {
  return {
    id: row.id as string,
    userId: row.user_id as string,
    type: row.type as NotificationType,
    title: row.title as string,
    body: row.body as string,
    linkTo: (row.link_to as string) ?? undefined,
    relatedApprovalId: (row.related_approval_id as string) ?? undefined,
    read: row.read as boolean,
    createdAt: row.created_at as string,
  };
}

// --- CRUD ---

export async function getNotifications(userId: string): Promise<Notification[]> {
  const { data, error } = await supabase
    .from('notifications')
    .select('*')
    .eq('user_id', userId)
    .order('created_at', { ascending: false })
    .limit(50);

  if (error) {
    console.error('getNotifications error:', error);
    return [];
  }
  return (data ?? []).map(dbToNotif);
}

export async function getUnreadCount(userId: string): Promise<number> {
  const { count, error } = await supabase
    .from('notifications')
    .select('*', { count: 'exact', head: true })
    .eq('user_id', userId)
    .eq('read', false);

  if (error) {
    console.error('getUnreadCount error:', error);
    return 0;
  }
  return count ?? 0;
}

export async function createNotification(
  n: Omit<Notification, 'id' | 'createdAt' | 'read'>,
): Promise<Notification | null> {
  const row = {
    user_id: n.userId,
    type: n.type,
    title: n.title,
    body: n.body,
    link_to: n.linkTo ?? null,
    related_approval_id: n.relatedApprovalId ?? null,
    read: false,
  };

  const { data, error } = await supabase
    .from('notifications')
    .insert(row)
    .select()
    .single();

  if (error) {
    console.error('createNotification error:', error);
    return null;
  }
  return dbToNotif(data);
}

export async function markAsRead(id: string): Promise<void> {
  const { error } = await supabase
    .from('notifications')
    .update({ read: true })
    .eq('id', id);

  if (error) console.error('markAsRead error:', error);
}

export async function markAllAsRead(userId: string): Promise<void> {
  const { error } = await supabase
    .from('notifications')
    .update({ read: true })
    .eq('user_id', userId)
    .eq('read', false);

  if (error) console.error('markAllAsRead error:', error);
}