// Image URL validation utilities for the ImageInput component

import { apiClient } from './api';

export interface ImageValidationResult {
  isValid: boolean;
  error?: string;
  detectedType?: string;
  filename?: string;
  isCorsBlocked?: boolean;
  base64Data?: string;
}

export interface ImageInputMode {
  type: 'file' | 'url' | null;
  value?: File | string;
}

// Supported image MIME types and extensions
export const IMAGE_MIME_TYPES = [
  'image/jpeg',
  'image/jpg',
  'image/png',
  'image/gif',
  'image/webp',
  'image/bmp',
  'image/svg+xml',
  'image/tiff'
] as const;

export const IMAGE_EXTENSIONS = ['jpg', 'jpeg', 'png', 'gif', 'webp', 'bmp', 'svg', 'tiff'] as const;

export type ImageExtension = typeof IMAGE_EXTENSIONS[number];

// Extract extension from filename or URL
export function extractExtension(filenameOrUrl: string): string | null {
  // Remove query parameters and fragments
  const cleanUrl = filenameOrUrl.split('?')[0].split('#')[0];

  // Get the last part after dot
  const extension = cleanUrl.split('.').pop()?.toLowerCase();

  return extension || null;
}

// Check if URL contains image extension (more flexible than just checking the end)
export function hasImageExtension(url: string): boolean {
  const extension = extractExtension(url);
  return extension ? isValidImageExtension(extension) : false;
}

// Check if extension is a valid image extension
export function isValidImageExtension(extension: string): extension is ImageExtension {
  return IMAGE_EXTENSIONS.includes(extension as ImageExtension);
}

// Get MIME type from extension
export function getMimeTypeFromExtension(extension: string): string {
  const extToMime: Record<ImageExtension, string> = {
    'jpg': 'image/jpeg',
    'jpeg': 'image/jpeg',
    'png': 'image/png',
    'gif': 'image/gif',
    'webp': 'image/webp',
    'bmp': 'image/bmp',
    'svg': 'image/svg+xml',
    'tiff': 'image/tiff'
  };

  return extToMime[extension as ImageExtension] || 'image/unknown';
}

// Validate file object
export function validateFile(file: File): ImageValidationResult {
  // Check if file is empty
  if (!file || file.size === 0) {
    return {
      isValid: false,
      error: 'File is empty or invalid'
    };
  }

  // Check file size (max 10MB)
  const maxSize = 10 * 1024 * 1024; // 10MB
  if (file.size > maxSize) {
    return {
      isValid: false,
      error: `File size (${(file.size / 1024 / 1024).toFixed(1)}MB) exceeds 10MB limit`
    };
  }

  // Check MIME type
  if (!IMAGE_MIME_TYPES.includes(file.type as any)) {
    return {
      isValid: false,
      error: `File type '${file.type}' is not supported. Supported formats: ${IMAGE_EXTENSIONS.join(', ')}`
    };
  }

  return {
    isValid: true,
    detectedType: file.type,
    filename: file.name
  };
}

// Basic URL validation without network requests
export function validateUrlFormat(url: string): ImageValidationResult {
  try {
    new URL(url);
  } catch {
    return {
      isValid: false,
      error: 'Invalid URL format'
    };
  }

  // Check if it has a valid image extension
  if (!hasImageExtension(url)) {
    return {
      isValid: false,
      error: 'URL does not point to a supported image format. Supported formats: ' + IMAGE_EXTENSIONS.join(', ')
    };
  }

  // Basic validation passed - return the extension-based result
  const extension = extractExtension(url);
  return {
    isValid: true,
    detectedType: extension ? getMimeTypeFromExtension(extension) : undefined,
    filename: url.split('/').pop() || url
  };
}

// Validate image URL using server-side download endpoint
export async function validateImageUrlWithBase64(url: string): Promise<ImageValidationResult> {
  // First validate URL format and extension
  const formatValidation = validateUrlFormat(url);
  if (!formatValidation.isValid) {
    return formatValidation;
  }

  try {
    // Use server-side download endpoint to avoid CORS issues
    const result = await apiClient.downloadImageFromUrl(url);

    return {
      isValid: true,
      detectedType: result.mimeType,
      filename: result.filename,
      base64Data: result.base64Data
    };

  } catch (error) {
    return {
      isValid: false,
      error: `Failed to download image from URL: ${error instanceof Error ? error.message : 'Unknown error'}`
    };
  }
}

// Validate image input (file or URL) with base64 conversion
export async function validateImageInput(
  input: File | string
): Promise<ImageValidationResult> {
  if (input instanceof File) {
    return validateFile(input);
  } else {
    return await validateImageUrlWithBase64(input);
  }
}

// Get display name for image input
export function getImageDisplayName(input: File | string): string {
  if (input instanceof File) {
    return input.name;
  } else {
    const url = new URL(input);
    return url.pathname.split('/').pop() || input;
  }
}

// Convert file to data URL for preview
export function fileToDataURL(file: File): Promise<string> {
  return new Promise((resolve, reject) => {
    const reader = new FileReader();
    reader.onload = () => resolve(reader.result as string);
    reader.onerror = reject;
    reader.readAsDataURL(file);
  });
}