import type { FileServiceConfig, ValidationResult } from '../types';

export function validateFile(
  file: File,
  config?: FileServiceConfig
): ValidationResult {
  const errors: string[] = [];
  const warnings: string[] = [];

  // Size validation
  if (config?.maxFileSize && file.size > config.maxFileSize) {
    const maxSizeMB = (config.maxFileSize / (1024 * 1024)).toFixed(2);
    const fileSizeMB = (file.size / (1024 * 1024)).toFixed(2);
    errors.push(
      `File size (${fileSizeMB}MB) exceeds maximum allowed size (${maxSizeMB}MB)`
    );
  }

  // Type validation
  if (config?.acceptedFileTypes && config.acceptedFileTypes.length > 0) {
    const isAccepted = config.acceptedFileTypes.some((acceptedType) => {
      if (acceptedType.endsWith('/*')) {
        // Wildcard match (e.g., "image/*")
        const baseType = acceptedType.split('/')[0];
        return file.type.startsWith(baseType + '/');
      }
      return file.type === acceptedType;
    });

    if (!isAccepted) {
      errors.push(
        `File type "${file.type}" is not accepted. Allowed types: ${config.acceptedFileTypes.join(', ')}`
      );
    }
  }

  // Additional validations
  if (file.size === 0) {
    errors.push('File is empty');
  }

  if (file.name.length === 0) {
    errors.push('File name is empty');
  }

  // Warning for large files
  if (file.size > 10 * 1024 * 1024) {
    warnings.push('File is larger than 10MB, upload may take longer');
  }

  return {
    valid: errors.length === 0,
    errors,
    warnings,
  };
}

export function getFileType(file: File): string {
  return file.type || 'application/octet-stream';
}

export function isImageFile(file: File): boolean {
  return file.type.startsWith('image/');
}

export function isPdfFile(file: File): boolean {
  return file.type === 'application/pdf';
}

export function isWordFile(file: File): boolean {
  return (
    file.type ===
      'application/vnd.openxmlformats-officedocument.wordprocessingml.document' ||
    file.type === 'application/msword'
  );
}

export function isExcelFile(file: File): boolean {
  return (
    file.type ===
      'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet' ||
    file.type === 'application/vnd.ms-excel'
  );
}

export function isCsvFile(file: File): boolean {
  return (
    file.type === 'text/csv' ||
    file.name.toLowerCase().endsWith('.csv')
  );
}

export function formatFileSize(bytes: number): string {
  if (bytes === 0) return '0 Bytes';
  const k = 1024;
  const sizes = ['Bytes', 'KB', 'MB', 'GB', 'TB'];
  const i = Math.floor(Math.log(bytes) / Math.log(k));
  return Math.round((bytes / Math.pow(k, i)) * 100) / 100 + ' ' + sizes[i];
}