import type { FileValidationConfig } from '@admin/utils/validation/file-validation-config'
import type { FileValidationError } from '@admin/utils/validation/file-validation-error'
import type { FileValidationResult } from '@admin/utils/validation/file-validation-result'
import { isFileTypeAllowed } from '@admin/utils/validation/is-file-type-allowed'

export function validateFiles(
  files: File[],
  config: FileValidationConfig = {}
): FileValidationResult {
  const { maxSizeInBytes, allowedTypes, maxFiles } = config

  const errors: FileValidationError[] = []

  if (typeof maxFiles === 'number' && maxFiles > 0 && files.length > maxFiles) {
    errors.push({
      filename: '',
      error: `Too many files. Maximum is ${maxFiles}.`
    })
  }

  for (const file of files) {
    if (typeof maxSizeInBytes === 'number' && maxSizeInBytes > 0 && file.size > maxSizeInBytes) {
      const maxMB = Math.round(maxSizeInBytes / (1024 * 1024))
      errors.push({
        filename: file.name,
        error: `File exceeds maximum size of ${maxMB}MB.`
      })
    }

    if (allowedTypes && allowedTypes.length > 0 && !isFileTypeAllowed(file, allowedTypes)) {
      errors.push({
        filename: file.name,
        error: `File type "${file.type || 'unknown'}" is not allowed.`
      })
    }
  }

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