/*
 * File: fileUpload.ts
 * Description: Utility functions for handling file uploads in React Native
 * Design & Developed by Tech4Biz Solutions
 * Copyright (c) Spurrin Innovations. All rights reserved.
 */

// ============================================================================
// INTERFACES
// ============================================================================

/**
 * FileData Interface
 * 
 * Purpose: Defines the structure for file data from image picker
 */
export interface FileData {
  uri: string;
  name?: string;
  type?: string;
  size?: number;
}

/**
 * UploadFile Interface
 * 
 * Purpose: Defines the structure for file object in FormData
 */
export interface UploadFile {
  uri: string;
  name: string;
  type: string;
}

// ============================================================================
// FILE UPLOAD UTILITIES
// ============================================================================

/**
 * Prepare File for Upload
 * 
 * Purpose: Convert FileData to proper UploadFile structure for FormData
 * 
 * @param fileData - File data from image picker
 * @param fieldName - Form field name for the file
 * @returns Properly formatted UploadFile object
 */
export const prepareFileForUpload = (
  fileData: FileData,
  fieldName: string = 'file'
): UploadFile => {
  // Extract file extension from URI
  const uri = fileData.uri;
  const fileName = fileData.name || `${fieldName}_${Date.now()}`;
  
  // Determine file extension and MIME type
  let fileExtension = 'jpg';
  let mimeType = 'image/jpeg';
  
  if (fileData.type) {
    // Use provided type
    mimeType = fileData.type;
    fileExtension = mimeType.split('/')[1] || 'jpg';
  } else {
    // Extract from URI
    const uriParts = uri.split('.');
    if (uriParts.length > 1) {
      fileExtension = uriParts[uriParts.length - 1].toLowerCase();
      
      // Map extension to MIME type
      switch (fileExtension) {
        case 'png':
          mimeType = 'image/png';
          break;
        case 'jpeg':
        case 'jpg':
          mimeType = 'image/jpeg';
          break;
        case 'gif':
          mimeType = 'image/gif';
          break;
        case 'webp':
          mimeType = 'image/webp';
          break;
        default:
          mimeType = 'image/jpeg';
          fileExtension = 'jpg';
      }
    }
  }
  
  // Ensure filename has proper extension
  const finalFileName = fileName.includes('.') 
    ? fileName 
    : `${fileName}.${fileExtension}`;
  
  return {
    uri,
    name: finalFileName,
    type: mimeType,
  };
};

/**
 * Create FormData with File
 * 
 * Purpose: Create FormData object with proper file attachment
 * 
 * @param data - Object containing form fields
 * @param fileData - File data to upload
 * @param fileFieldName - Form field name for the file
 * @returns FormData object ready for upload
 */
export const createFormDataWithFile = (
  data: Record<string, any>,
  fileData?: FileData,
  fileFieldName: string = 'file'
): FormData => {
  const formData = new FormData();
  
  // Add regular form fields
  Object.keys(data).forEach(key => {
    if (data[key] !== null && data[key] !== undefined) {
      formData.append(key, String(data[key]));
    }
  });
  
  // Add file if provided
  if (fileData) {
    const uploadFile = prepareFileForUpload(fileData, fileFieldName);
    formData.append(fileFieldName, uploadFile as any);
  }
  
  return formData;
};

/**
 * Validate File Type
 * 
 * Purpose: Check if file type is allowed
 * 
 * @param fileData - File data to validate
 * @param allowedTypes - Array of allowed MIME types
 * @returns Boolean indicating if file type is allowed
 */
export const validateFileType = (
  fileData: FileData,
  allowedTypes: string[] = ['image/jpeg', 'image/jpg', 'image/png']
): boolean => {
  if (!fileData.type) {
    // If no type provided, try to determine from URI
    const uri = fileData.uri.toLowerCase();
    if (uri.includes('.jpg') || uri.includes('.jpeg')) {
      return allowedTypes.includes('image/jpeg') || allowedTypes.includes('image/jpg');
    }
    if (uri.includes('.png')) {
      return allowedTypes.includes('image/png');
    }
    return false;
  }
  
  return allowedTypes.includes(fileData.type.toLowerCase());
};

/**
 * Validate File Size
 * 
 * Purpose: Check if file size is within limits
 * 
 * @param fileData - File data to validate
 * @param maxSizeMB - Maximum file size in MB
 * @returns Boolean indicating if file size is acceptable
 */
export const validateFileSize = (
  fileData: FileData,
  maxSizeMB: number = 10
): boolean => {
  if (!fileData.size) {
    return true; // Skip validation if size not available
  }
  
  const maxSizeBytes = maxSizeMB * 1024 * 1024;
  return fileData.size <= maxSizeBytes;
};

/**
 * Format File Size
 * 
 * Purpose: Convert bytes to human readable format
 * 
 * @param bytes - File size in bytes
 * @returns Formatted file size string
 */
export const formatFileSize = (bytes?: number): string => {
  if (!bytes) return '';
  
  const sizes = ['Bytes', 'KB', 'MB', 'GB'];
  if (bytes === 0) return '0 Bytes';
  
  const i = Math.floor(Math.log(bytes) / Math.log(1024));
  return Math.round(bytes / Math.pow(1024, i) * 100) / 100 + ' ' + sizes[i];
};

/**
 * Get File Type Display Name
 * 
 * Purpose: Get user-friendly display name for file type
 * 
 * @param mimeType - MIME type string
 * @returns Display name for file type
 */
export const getFileTypeDisplay = (mimeType: string): string => {
  const typeMap: Record<string, string> = {
    'image/jpeg': 'JPEG',
    'image/jpg': 'JPEG',
    'image/png': 'PNG',
    'image/gif': 'GIF',
    'image/webp': 'WebP',
  };
  
  return typeMap[mimeType.toLowerCase()] || 'Image';
};

/*
 * End of File: fileUpload.ts
 * Design & Developed by Tech4Biz Solutions
 * Copyright (c) Spurrin Innovations. All rights reserved.
 */