import type { StringFormat } from "../types.js";

// Email must have at least one dot after the @
const EMAIL_RE =
  /^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)+$/;

const UUID_RE =
  /^[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}$/;

const IPV4_RE =
  /^(?:(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)\.){3}(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)$/;

const IPV6_RE =
  /^(?:(?:[0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}|(?:[0-9a-fA-F]{1,4}:){1,7}:|(?:[0-9a-fA-F]{1,4}:){1,6}:[0-9a-fA-F]{1,4}|(?:[0-9a-fA-F]{1,4}:){1,5}(?::[0-9a-fA-F]{1,4}){1,2}|(?:[0-9a-fA-F]{1,4}:){1,4}(?::[0-9a-fA-F]{1,4}){1,3}|(?:[0-9a-fA-F]{1,4}:){1,3}(?::[0-9a-fA-F]{1,4}){1,4}|(?:[0-9a-fA-F]{1,4}:){1,2}(?::[0-9a-fA-F]{1,4}){1,5}|[0-9a-fA-F]{1,4}:(?::[0-9a-fA-F]{1,4}){1,6}|:(?::[0-9a-fA-F]{1,4}){1,7}|::)$/;

// ISO 8601 date: YYYY-MM-DD
const DATE_RE = /^\d{4}-(?:0[1-9]|1[0-2])-(?:0[1-9]|[12]\d|3[01])$/;

// ISO 8601 date-time: YYYY-MM-DDTHH:MM:SS with optional fractional seconds and timezone
const DATETIME_RE =
  /^\d{4}-(?:0[1-9]|1[0-2])-(?:0[1-9]|[12]\d|3[01])T(?:[01]\d|2[0-3]):[0-5]\d:[0-5]\d(?:\.\d+)?(?:Z|[+-](?:[01]\d|2[0-3]):[0-5]\d)$/;

function isValidDate(str: string): boolean {
  if (!DATE_RE.test(str)) return false;
  const [y, m, d] = str.split("-").map(Number);
  const date = new Date(y, m - 1, d);
  // new Date() maps years 0-99 to 1900-1999; undo that so early ISO years
  // (e.g. 0050-01-01) are not falsely rejected.
  date.setFullYear(y);
  return (
    date.getFullYear() === y &&
    date.getMonth() === m - 1 &&
    date.getDate() === d
  );
}

function isValidDateTime(str: string): boolean {
  if (!DATETIME_RE.test(str)) return false;
  // Validate the date portion
  const datePart = str.substring(0, 10);
  return isValidDate(datePart);
}

function isValidUrl(str: string): boolean {
  try {
    const url = new URL(str);
    // Only accept http and https protocols
    return url.protocol === "http:" || url.protocol === "https:";
  } catch {
    return false;
  }
}

const FORMAT_VALIDATORS: Record<StringFormat, (val: string) => boolean> = {
  email: (val) => EMAIL_RE.test(val),
  url: isValidUrl,
  uuid: (val) => UUID_RE.test(val),
  ipv4: (val) => IPV4_RE.test(val),
  ipv6: (val) => IPV6_RE.test(val),
  date: isValidDate,
  "date-time": isValidDateTime,
};

const FORMAT_NAME_RE = /^[A-Za-z][A-Za-z0-9-]*$/;

export function validateFormat(value: string, format: string): boolean {
  if (!FORMAT_NAME_RE.test(format)) return false;
  const validator = FORMAT_VALIDATORS[format as StringFormat];
  if (!validator) return true; // valid custom formats pass
  return validator(value);
}