import { z } from 'zod';

/**
 * Regular expression to validate a data URL.
 * The pattern matches data URLs that start with `data:`, optionally followed by a media type,
 * optionally followed by an encoding (e.g., `base64`), and ending with base64 encoded data.
 */
export const zodDataUrlRegex = /^data:(?:[\w+\/-]+)?(?:[\w+\/-]+)?;base64,[\s\S]*$/;

/**
 * Zod schema for validating data URLs.
 * This schema ensures that the input string matches the format of a data URL.
 *
 * @example
 * const result = dataUrlSchema.safeParse('data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDCAAAAC0BEMAAW9R3AAAAAElFTkSuQmCC');
 * if (result.success) {
 *   console.log('Valid data URL:', result.data);
 * } else {
 *   console.error('Validation error:', result.error.errors);
 * }
 */
export const zodDataUrlSchema = z.string().refine(value => zodDataUrlRegex.test(value), {
  message: 'Invalid data URL',
});


//===============================================================================
/**
 * A schema for validating Base64 encoded strings.
 *
 * This schema checks if the string is valid Base64 and ensures that the first 20 characters
 * do not contain a comma.
 *
 * @example
 * ```typescript
 * const validString = 'SGVsbG8sIHdvcmxkIQ=='; // Base64 for "Hello, world!"
 * const invalidString = 'SGVsbG8sIHdvcmxkIQ,,=='; // Invalid due to commas
 *
 * console.log(base64Schema.safeParse(validString).success); // true
 * console.log(base64Schema.safeParse(invalidString).success); // false
 * ```
 */
export const base64Schema = z.string().refine(value => {
  // Regular expression for Base64 validation
  const isBase64 = /^[A-Za-z0-9+/=]*$/.test(value) && (value.length % 4 === 0);
  // Check if the first 20 characters do not contain a comma
  return isBase64 && !value.substring(0, 20).includes(',');
}, {
  message: 'Invalid Base64 string or comma found in the first 20 characters'
});

/**
 * Validates a given string against the Base64 schema.
 *
 * @param input - The string to validate.
 * @returns `true` if the input is valid according to the schema, `false` otherwise.
 *
 * @example
 * ```typescript
 * console.log(validateInput('SGVsbG8sIHdvcmxkIQ==')); // true
 * console.log(validateInput('SGVsbG8sIHdvcmxkIQ,,==')); // false
 * ```
 */