// The device sheet's rules for what may be typed into a field: Java's
// EingabenUeberpruefung as FILIUS' settings panels use it
// (JHostKonfiguration, JSwitchKonfiguration, JModemKonfiguration), measured
// with tools/java-oracle's SheetRun (test/sheet.java.json).
//
// Java judges a text twice: while it is typed, the panel colours it red when
// the pattern does not match; when the field loses the focus, the model's
// setter takes it or keeps the old value — and the two disagree. Java takes
// red text ("10..0.0.1", "+10.0.0.1", "-0.0.0.1", Arabic-Indic digits, a
// retention time of "-5"), refuses black text (".0.0.1", a retention time
// past Long's range), and a modem takes any int as its port (0, 65536, -1),
// unchecked. Here one rule decides both: a text is taken exactly when it is
// not marked. What is not taken is not thrown away either (Java puts the old
// value back into the field without a word): the sheet keeps it, marked,
// until it is mended (plan I6).
//
// Spaces around an address or a number are left out (Java refuses
// " 10.0.0.1"; a phone's keyboard puts a space after a word). A name and an
// SSID are taken as typed, spaces included, as Java takes them.

import { IP_ADDRESS_PATTERN, javaIpCheck } from '@mdg-filius/core';

export type FieldRule = 'name' | 'ipAddress' | 'ipAddressOrEmpty' | 'subnetMask' | 'ssid' | 'seconds' | 'port';

/** What a field's text comes to: the value the device takes, or that it takes none. */
export type CheckedField = { readonly value: string } | { readonly invalid: true };

/** EingabenUeberpruefung.musterSubNetz. */
const SUBNET_MASK_PATTERN = /^(0*([1-9]|1?[0-9]{1,2}|2[0-4]?[0-9]|25[0-5]))\.((0*([0-9]|1?[0-9]{1,2}|2[0-4]?[0-9]|25[0-5]))\.){2}(0*([0-9]|1?[0-9]{1,2}|2[0-4]?[0-9]|25[0-5]))$/;
/** EingabenUeberpruefung.musterServiceSetIdentifier: printable ASCII, at least one character. */
const SSID_PATTERN = /^[ -~]+$/;
/** EingabenUeberpruefung.musterPort: 1 to 65535, no leading zero. */
const PORT_PATTERN = /^([1-9]|[1-9][0-9]{1,3}|[1-5][0-9]{1,4}|6[0-4][0-9]{3}|65[0-4][0-9]{2}|655[0-2][0-9]|6553[0-5])$/;
/** EingabenUeberpruefung.musterNurZahlen, at least one digit (Java's Long.parseLong refuses none). */
const DIGITS_PATTERN = /^[0-9]+$/;

const INVALID: CheckedField = { invalid: true };

/**
 * An address as the panel's pattern and the model's IP.ipCheck both accept
 * it: neither alone (the pattern lets ".0.0.1" through, ipCheck "10..0.0.1"
 * and "+10.0.0.1"); the device keeps ipCheck's form ("010.0.0.1" is 10.0.0.1).
 */
function address(text: string, pattern: RegExp): CheckedField {
  const canonical = javaIpCheck(text);
  return canonical !== null && pattern.test(text) ? { value: canonical } : INVALID;
}

export function checkField(rule: FieldRule, text: string): CheckedField {
  switch (rule) {
    case 'name':
      return { value: text };
    case 'ssid':
      return SSID_PATTERN.test(text) ? { value: text } : INVALID;
    case 'ipAddress':
      return address(text.trim(), IP_ADDRESS_PATTERN);
    case 'ipAddressOrEmpty':
      return text.trim() === '' ? { value: '' } : address(text.trim(), IP_ADDRESS_PATTERN);
    case 'subnetMask':
      return address(text.trim(), SUBNET_MASK_PATTERN);
    case 'seconds': {
      const digits = text.trim();
      // In milliseconds the device's number must stay exact.
      return DIGITS_PATTERN.test(digits) && Number(digits) * 1000 <= Number.MAX_SAFE_INTEGER ? { value: String(Number(digits)) } : INVALID;
    }
    case 'port':
      return PORT_PATTERN.test(text.trim()) ? { value: text.trim() } : INVALID;
  }
}