graphs/src/dataService.ts

import type { OrderData, StockData } from './types';

const API_URL = import.meta.env.VITE_API_URL || '/api';

export const login = async (email: string, password: string): Promise<boolean> => {
  try {
    const response = await fetch(`${API_URL}/login`, {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
      },
      body: JSON.stringify({ email, password }),
    });

    if (response.ok) {
      const data = await response.json();
      localStorage.setItem('auth_token', data.token);
      return true;
    }
    return false;
  } catch (error) {
    console.error('Login failed', error);
    return false;
  }
};

export const logout = () => {
  localStorage.removeItem('auth_token');
  window.location.href = '/#/login';
};

export const isAuthenticated = (): boolean => {
  return !!localStorage.getItem('auth_token');
};

export const fetchStock = async (): Promise<StockData[]> => {
    try {
        const token = localStorage.getItem('auth_token');
        const response = await fetch(`${API_URL}/stock`, {
            headers: {
                'Authorization': `Bearer ${token}`
            }
        });
        if (response.status === 401 || response.status === 403) {
            logout();
            return [];
        }
        if (!response.ok) return [];
        return await response.json();
    } catch {
        return [];
    }
};

export const fetchData = async (): Promise<OrderData[]> => {
    try {
        const token = localStorage.getItem('auth_token');
        const response = await fetch(`${API_URL}/data`, {
            headers: {
                'Authorization': `Bearer ${token}`
            }
        });
        if (response.status === 401 || response.status === 403) {
            logout();
            return [];
        }
        if (!response.ok) return [];
        return await response.json();
    } catch (error) {
        console.error("Fetch failed", error);
        return [];
    }
};

export const parseOrderDate = (dateStr: string): Date => {
  if (!dateStr) return new Date(0);
  if (dateStr.includes('T')) return new Date(dateStr);
  const parts = dateStr.split(/[-/]/);
  if (parts.length === 3) {
    if (parts[0].length === 4) {
      // YYYY-MM-DD
      return new Date(Number(parts[0]), Number(parts[1]) - 1, Number(parts[2]));
    } else {
      // DD-MM-YYYY
      return new Date(Number(parts[2]), Number(parts[1]) - 1, Number(parts[0]));
    }
  }
  const fallback = new Date(dateStr);
  return isNaN(fallback.getTime()) ? new Date(0) : fallback;
};

export const exportToCSV = (data: Record<string, unknown>[], filename: string) => {
  if (!data || !data.length) return;
  
  const headers = Object.keys(data[0]);
  const csvRows = [];
  
  // Add headers
  csvRows.push(headers.join(','));
  
  // Add rows
  for (const row of data) {
    const values = headers.map(header => {
      const val = row[header];
      const escaped = String(val ?? '').replace(/"/g, '""');
      return `"${escaped}"`;
    });
    csvRows.push(values.join(','));
  }
  
  const csvString = csvRows.join('\n');
  const blob = new Blob([csvString], { type: 'text/csv;charset=utf-8;' });
  const link = document.createElement('a');
  if (link.download !== undefined) {
    const url = URL.createObjectURL(blob);
    link.setAttribute('href', url);
    link.setAttribute('download', filename);
    link.style.visibility = 'hidden';
    document.body.appendChild(link);
    link.click();
    document.body.removeChild(link);
  }
};