import { type MaybeRef, get } from '@vueuse/core';
import QRCode, { type QRCodeToDataURLOptions } from 'qrcode';
import { isRef, ref, watch } from 'vue';

export const wifiEncryptions = ['WEP', 'WPA', 'nopass', 'WPA2-EAP'] as const;
export type WifiEncryption = typeof wifiEncryptions[number];

// @see https://en.wikipedia.org/wiki/Extensible_Authentication_Protocol
// for a list of available EAP methods. There are a lot (40!) of them.
export const EAPMethods = [
  'MD5',
  'POTP',
  'GTC',
  'TLS',
  'IKEv2',
  'SIM',
  'AKA',
  'AKA\'',
  'TTLS',
  'PWD',
  'LEAP',
  'PSK',
  'FAST',
  'TEAP',
  'EKE',
  'NOOB',
  'PEAP',
] as const;
export type EAPMethod = typeof EAPMethods[number];

export const EAPPhase2Methods = [
  'None',
  'MSCHAPV2',
] as const;
export type EAPPhase2Method = typeof EAPPhase2Methods[number];

interface IWifiQRCodeOptions {
  ssid: MaybeRef<string>
  password: MaybeRef<string>
  eapMethod: MaybeRef<EAPMethod>
  isHiddenSSID: MaybeRef<boolean>
  eapAnonymous: MaybeRef<boolean>
  eapIdentity: MaybeRef<string>
  eapPhase2Method: MaybeRef<EAPPhase2Method>
  color: { foreground: MaybeRef<string>; background: MaybeRef<string> }
  options?: QRCodeToDataURLOptions
}

interface GetQrCodeTextOptions {
  ssid: string
  password: string
  encryption: WifiEncryption
  eapMethod: EAPMethod
  isHiddenSSID: boolean
  eapAnonymous: boolean
  eapIdentity: string
  eapPhase2Method: EAPPhase2Method
}

function escapeString(str: string) {
  // replaces \, ;, ,, " and : with the same character preceded by a backslash
  return str.replace(/([\\;,:"])/g, '\\$1');
}

function getQrCodeText(options: GetQrCodeTextOptions): string | null {
  const { ssid, password, encryption, eapMethod, isHiddenSSID, eapAnonymous, eapIdentity, eapPhase2Method } = options;
  if (!ssid) {
    return null;
  }
  if (encryption === 'nopass') {
    return `WIFI:S:${escapeString(ssid)};;`; // type can be omitted in that case, and password is not needed, makes the QR Code smaller
  }
  if (encryption !== 'WPA2-EAP' && password) {
    // EAP has a lot of options, so we'll handle it separately
    // WPA and WEP are pretty simple though.
    return `WIFI:S:${escapeString(ssid)};T:${encryption};P:${escapeString(password)};${isHiddenSSID ? 'H:true' : ''};`;
  }
  if (encryption === 'WPA2-EAP' && password && eapMethod) {
    // WPA2-EAP string is a lot more complex, first off, we drop the text if there is no identity, and it's not anonymous.
    if (!eapIdentity && !eapAnonymous) {
      return null;
    }
    // From reading, I could only find that a phase 2 is required for the PEAP method, I may be wrong though, I didn't read the whole spec.
    if (eapMethod === 'PEAP' && !eapPhase2Method) {
      return null;
    }
    // The string is built in the following order:
    // 1. SSID
    // 2. Authentication type
    // 3. Password
    // 4. EAP method
    // 5. EAP phase 2 method
    // 6. Identity or anonymous if checked
    // 7. Hidden SSID if checked
    const identity = eapAnonymous ? 'A:anon' : `I:${escapeString(eapIdentity)}`;
    const phase2 = eapPhase2Method !== 'None' ? `PH2:${eapPhase2Method};` : '';
    return `WIFI:S:${escapeString(ssid)};T:WPA2-EAP;P:${escapeString(password)};E:${eapMethod};${phase2}${identity};${isHiddenSSID ? 'H:true' : ''};`;
  }
  return null;
}

export function useWifiQRCode({
  ssid,
  password,
  eapMethod,
  isHiddenSSID,
  eapAnonymous,
  eapIdentity,
  eapPhase2Method,
  color: { background, foreground },
  options,
}: IWifiQRCodeOptions) {
  const qrcode = ref('');
  const encryption = ref<WifiEncryption>('WPA');

  watch(
    [ssid, password, encryption, eapMethod, isHiddenSSID, eapAnonymous, eapIdentity, eapPhase2Method, background, foreground].filter(isRef),
    async () => {
      // @see https://github.com/zxing/zxing/wiki/Barcode-Contents#wi-fi-network-config-android-ios-11
      // This is the full spec, there's quite a bit of logic to generate the string embeddedin the QR code.
      const text = getQrCodeText({
        ssid: get(ssid),
        password: get(password),
        encryption: get(encryption),
        eapMethod: get(eapMethod),
        isHiddenSSID: get(isHiddenSSID),
        eapAnonymous: get(eapAnonymous),
        eapIdentity: get(eapIdentity),
        eapPhase2Method: get(eapPhase2Method),
      });
      if (text) {
        qrcode.value = await QRCode.toDataURL(get(text).trim(), {
          color: {
            dark: get(foreground),
            light: get(background),
            ...options?.color,
          },
          errorCorrectionLevel: 'M',
          ...options,
        });
      }
    },
    { immediate: true },
  );
  return { qrcode, encryption };
}