/**
 * API Client for backend communication
 */

import { formatDateISO } from '../utils/dateUtils.js';
import { showNotification } from '../ui/notifications.js';

/**
 * Fetch entries from the backend
 * @param {string|null} fromDate - Start date (YYYY-MM-DD)
 * @param {string|null} toDate - End date (YYYY-MM-DD)
 * @returns {Promise<Array>} - Array of entries
 */
export async function fetchEntries(fromDate = null, toDate = null) {
  try {
    let url = '/api/entries';
    const params = new URLSearchParams();
    
    if (fromDate) params.append('from', fromDate);
    if (toDate) params.append('to', toDate);
    
    if (params.toString()) {
      url += '?' + params.toString();
    }
    
    const response = await fetch(url);
    
    if (!response.ok) {
      throw new Error('Failed to fetch entries');
    }
    
    const entries = await response.json();
    return entries;
  } catch (error) {
    console.error('Error fetching entries:', error);
    showNotification('Fehler beim Laden der Einträge', 'error');
    return [];
  }
}

/**
 * Create a new entry
 * @param {string} date - Date in DD.MM.YYYY format
 * @param {string} startTime - Start time HH:MM
 * @param {string} endTime - End time HH:MM
 * @param {number|null} pauseMinutes - Pause in minutes
 * @param {string} location - Location (office/home)
 * @returns {Promise<Object|null>} - Created entry or null
 */
export async function createEntry(date, startTime, endTime, pauseMinutes, location) {
  try {
    const body = {
      date: formatDateISO(date),
      startTime,
      endTime,
      location: location || 'office'
    };
    
    // Only include pauseMinutes if explicitly provided (not empty)
    if (pauseMinutes !== null && pauseMinutes !== undefined && pauseMinutes !== '') {
      body.pauseMinutes = parseInt(pauseMinutes);
    }
    
    const response = await fetch('/api/entries', {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json'
      },
      body: JSON.stringify(body)
    });
    
    if (!response.ok) {
      const error = await response.json();
      throw new Error(error.error || 'Failed to create entry');
    }
    
    const entry = await response.json();
    return entry;
  } catch (error) {
    console.error('Error creating entry:', error);
    showNotification(error.message || 'Fehler beim Erstellen des Eintrags', 'error');
    return null;
  }
}

/**
 * Update an existing entry
 * @param {number} id - Entry ID
 * @param {string} date - Date in DD.MM.YYYY format
 * @param {string} startTime - Start time HH:MM
 * @param {string} endTime - End time HH:MM
 * @param {number|null} pauseMinutes - Pause in minutes
 * @param {string} location - Location (office/home)
 * @returns {Promise<Object|null>} - Updated entry or null
 */
export async function updateEntry(id, date, startTime, endTime, pauseMinutes, location) {
  try {
    const body = {
      date: formatDateISO(date),
      startTime,
      endTime,
      location: location || 'office'
    };
    
    // Only include pauseMinutes if explicitly provided (not empty)
    if (pauseMinutes !== null && pauseMinutes !== undefined && pauseMinutes !== '') {
      body.pauseMinutes = parseInt(pauseMinutes);
    }
    
    const response = await fetch(`/api/entries/${id}`, {
      method: 'PUT',
      headers: {
        'Content-Type': 'application/json'
      },
      body: JSON.stringify(body)
    });
    
    if (!response.ok) {
      const error = await response.json();
      throw new Error(error.error || 'Failed to update entry');
    }
    
    const entry = await response.json();
    return entry;
  } catch (error) {
    console.error('Error updating entry:', error);
    showNotification(error.message || 'Fehler beim Aktualisieren des Eintrags', 'error');
    return null;
  }
}

/**
 * Delete an entry
 * @param {number} id - Entry ID
 * @returns {Promise<boolean>} - True if successful
 */
export async function deleteEntry(id) {
  try {
    const response = await fetch(`/api/entries/${id}`, {
      method: 'DELETE'
    });
    
    if (!response.ok) {
      throw new Error('Failed to delete entry');
    }
    
    return true;
  } catch (error) {
    console.error('Error deleting entry:', error);
    showNotification('Fehler beim Löschen des Eintrags', 'error');
    return false;
  }
}

/**
 * Export entries as CSV
 * @param {string|null} fromDate - Start date (YYYY-MM-DD)
 * @param {string|null} toDate - End date (YYYY-MM-DD)
 */
export async function exportEntries(fromDate = null, toDate = null) {
  try {
    let url = '/api/export';
    const params = new URLSearchParams();
    
    if (fromDate) params.append('from', fromDate);
    if (toDate) params.append('to', toDate);
    
    if (params.toString()) {
      url += '?' + params.toString();
    }
    
    const response = await fetch(url);
    
    if (!response.ok) {
      throw new Error('Failed to export entries');
    }
    
    const blob = await response.blob();
    const downloadUrl = window.URL.createObjectURL(blob);
    const a = document.createElement('a');
    a.href = downloadUrl;
    a.download = 'zeiterfassung.csv';
    document.body.appendChild(a);
    a.click();
    document.body.removeChild(a);
    window.URL.revokeObjectURL(downloadUrl);
    
    showNotification('Export erfolgreich', 'success');
  } catch (error) {
    console.error('Error exporting entries:', error);
    showNotification('Fehler beim Exportieren', 'error');
  }
}