/*
   PDFSecurity - represents PDF security settings
   By Yang Liu <hi@zesik.com>
 */

import CryptoJS from 'crypto-js';
import saslprep from 'saslprep';

class PDFSecurity {
  static generateFileID(info = {}) {
    let infoStr = `${info.CreationDate.getTime()}\n`;

    for (let key in info) {
      if (!info.hasOwnProperty(key)) {
        continue;
      }
      infoStr += `${key}: ${info[key].toString()}\n`;
    }

    return wordArrayToBuffer(CryptoJS.MD5(infoStr));
  }

  static generateRandomWordArray(bytes) {
    return CryptoJS.lib.WordArray.random(bytes);
  }

  static create(document, options = {}) {
    if (!options.ownerPassword && !options.userPassword) {
      return null;
    }
    return new PDFSecurity(document, options);
  }

  constructor(document, options = {}) {
    if (!options.ownerPassword && !options.userPassword) {
      throw new Error('None of owner password and user password is defined.');
    }

    this.document = document;
    this._setupEncryption(options);
  }

  _setupEncryption(options) {
    switch (options.pdfVersion) {
      case '1.4':
      case '1.5':
        this.version = 2;
        break;
      case '1.6':
      case '1.7':
        this.version = 4;
        break;
      case '1.7ext3':
        this.version = 5;
        break;
      default:
        this.version = 1;
        break;
    }

    const encDict = {
      Filter: 'Standard'
    };

    switch (this.version) {
      case 1:
      case 2:
      case 4:
        this._setupEncryptionV1V2V4(this.version, encDict, options);
        break;
      case 5:
        this._setupEncryptionV5(encDict, options);
        break;
    }

    this.dictionary = this.document.ref(encDict);
  }

  _setupEncryptionV1V2V4(v, encDict, options) {
    let r, permissions;
    switch (v) {
      case 1:
        r = 2;
        this.keyBits = 40;
        permissions = getPermissionsR2(options.permissions);
        break;
      case 2:
        r = 3;
        this.keyBits = 128;
        permissions = getPermissionsR3(options.permissions);
        break;
      case 4:
        r = 4;
        this.keyBits = 128;
        permissions = getPermissionsR3(options.permissions);
        break;
    }

    const paddedUserPassword = processPasswordR2R3R4(options.userPassword);
    const paddedOwnerPassword = options.ownerPassword ?
      processPasswordR2R3R4(options.ownerPassword) : paddedUserPassword;

    const ownerPasswordEntry = getOwnerPasswordR2R3R4(r, this.keyBits, paddedUserPassword, paddedOwnerPassword);
    this.encryptionKey = getEncryptionKeyR2R3R4(r, this.keyBits, this.document._id,
      paddedUserPassword, ownerPasswordEntry, permissions);
    let userPasswordEntry;
    if (r === 2) {
      userPasswordEntry = getUserPasswordR2(this.encryptionKey);
    } else {
      userPasswordEntry = getUserPasswordR3R4(this.document._id, this.encryptionKey);
    }

    encDict.V = v;
    if (v >= 2) {
      encDict.Length = this.keyBits;
    }
    if (v === 4) {
      encDict.CF = {
        StdCF: {
          AuthEvent: 'DocOpen',
          CFM: 'AESV2',
          Length: this.keyBits / 8
        }
      };
      encDict.StmF = 'StdCF';
      encDict.StrF = 'StdCF';
    }
    encDict.R = r;
    encDict.O = wordArrayToBuffer(ownerPasswordEntry);
    encDict.U = wordArrayToBuffer(userPasswordEntry);
    encDict.P = permissions;
  }

  _setupEncryptionV5(encDict, options) {
    this.keyBits = 256;
    const permissions = getPermissionsR3(options);

    const processedUserPassword = processPasswordR5(options.userPassword);
    const processedOwnerPassword = options.ownerPassword ?
      processPasswordR5(options.ownerPassword) : processedUserPassword;

    this.encryptionKey = getEncryptionKeyR5(PDFSecurity.generateRandomWordArray);
    const userPasswordEntry = getUserPasswordR5(processedUserPassword, PDFSecurity.generateRandomWordArray);
    const userKeySalt = CryptoJS.lib.WordArray.create(userPasswordEntry.words.slice(10, 12), 8);
    const userEncryptionKeyEntry = getUserEncryptionKeyR5(processedUserPassword, userKeySalt, this.encryptionKey);
    const ownerPasswordEntry = getOwnerPasswordR5(processedOwnerPassword, userPasswordEntry,
      PDFSecurity.generateRandomWordArray);
    const ownerKeySalt = CryptoJS.lib.WordArray.create(ownerPasswordEntry.words.slice(10, 12), 8);
    const ownerEncryptionKeyEntry = getOwnerEncryptionKeyR5(processedOwnerPassword, ownerKeySalt, userPasswordEntry,
      this.encryptionKey);
    const permsEntry = getEncryptedPermissionsR5(permissions, this.encryptionKey, PDFSecurity.generateRandomWordArray);

    encDict.V = 5;
    encDict.Length = this.keyBits;
    encDict.CF = {
      StdCF: {
        AuthEvent: 'DocOpen',
        CFM: 'AESV3',
        Length: this.keyBits / 8
      }
    };
    encDict.StmF = 'StdCF';
    encDict.StrF = 'StdCF';
    encDict.R = 5;
    encDict.O = wordArrayToBuffer(ownerPasswordEntry);
    encDict.OE = wordArrayToBuffer(ownerEncryptionKeyEntry);
    encDict.U = wordArrayToBuffer(userPasswordEntry);
    encDict.UE = wordArrayToBuffer(userEncryptionKeyEntry);
    encDict.P = permissions;
    encDict.Perms = wordArrayToBuffer(permsEntry);
  }

  getEncryptFn(obj, gen) {
    let digest;
    if (this.version < 5) {
      digest = this.encryptionKey.clone().concat(CryptoJS.lib.WordArray.create([
        ((obj & 0xff) << 24) | ((obj & 0xff00) << 8) | ((obj >> 8) & 0xff00) | (gen & 0xff), (gen & 0xff00) << 16
      ], 5));
    }

    if (this.version === 1 || this.version === 2) {
      let key = CryptoJS.MD5(digest);
      key.sigBytes = Math.min(16, this.keyBits / 8 + 5);
      return buffer => wordArrayToBuffer(
        CryptoJS.RC4.encrypt(CryptoJS.lib.WordArray.create(buffer), key).ciphertext);
    }

    let key;
    if (this.version === 4) {
      key = CryptoJS.MD5(digest.concat(CryptoJS.lib.WordArray.create([0x73416c54], 4)));
    } else {
      key = this.encryptionKey;
    }

    const iv = PDFSecurity.generateRandomWordArray(16);
    const options = {
      mode: CryptoJS.mode.CBC,
      padding: CryptoJS.pad.Pkcs7,
      iv
    };

    return buffer => wordArrayToBuffer(
      iv.clone().concat(CryptoJS.AES.encrypt(CryptoJS.lib.WordArray.create(buffer), key, options).ciphertext));
  }

  end() {
    this.dictionary.end();
  }
}

function getPermissionsR2(permissionObject = {}) {
  let permissions = 0xffffffc0 >> 0;
  if (permissionObject.printing) {
    permissions |= 0b00000000010;
  }
  if (permissionObject.modifying) {
    permissions |= 0b000000001000;
  }
  if (permissionObject.copying) {
    permissions |= 0b000000010000;
  }
  if (permissionObject.annotating) {
    permissions |= 0b000000100000;
  }
  return permissions;
}

function getPermissionsR3(permissionObject = {}) {
  let permissions = 0xfffff0c0 >> 0;
  if (permissionObject.printing === 'lowResolution') {
    permissions |= 0b000000000100;
  }
  if (permissionObject.printing === 'highResolution') {
    permissions |= 0b100000000100;
  }
  if (permissionObject.modifying) {
    permissions |= 0b000000001000;
  }
  if (permissionObject.copying) {
    permissions |= 0b000000010000;
  }
  if (permissionObject.annotating) {
    permissions |= 0b000000100000;
  }
  if (permissionObject.fillingForms) {
    permissions |= 0b000100000000;
  }
  if (permissionObject.contentAccessibility) {
    permissions |= 0b001000000000;
  }
  if (permissionObject.documentAssembly) {
    permissions |= 0b010000000000;
  }
  return permissions;
}

function getUserPasswordR2(encryptionKey) {
  return CryptoJS.RC4.encrypt(processPasswordR2R3R4(), encryptionKey).ciphertext;
}

function getUserPasswordR3R4(documentId, encryptionKey) {
  const key = encryptionKey.clone();
  let cipher = CryptoJS.MD5(processPasswordR2R3R4().concat(CryptoJS.lib.WordArray.create(documentId)));
  for (let i = 0; i < 20; i++) {
    const xorRound = Math.ceil(key.sigBytes / 4);
    for (let j = 0; j < xorRound; j++) {
      key.words[j] = encryptionKey.words[j] ^ (i | (i << 8) | (i << 16) | (i << 24));
    }
    cipher = CryptoJS.RC4.encrypt(cipher, key).ciphertext;
  }
  return cipher.concat(CryptoJS.lib.WordArray.create(null, 16));
}

function getOwnerPasswordR2R3R4(r, keyBits, paddedUserPassword, paddedOwnerPassword) {
  let digest = paddedOwnerPassword;
  let round = r >= 3 ? 51 : 1;
  for (let i = 0; i < round; i++) {
    digest = CryptoJS.MD5(digest);
  }

  const key = digest.clone();
  key.sigBytes = keyBits / 8;
  let cipher = paddedUserPassword;
  round = r >= 3 ? 20 : 1;
  for (let i = 0; i < round; i++) {
    const xorRound = Math.ceil(key.sigBytes / 4);
    for (let j = 0; j < xorRound; j++) {
      key.words[j] = digest.words[j] ^ (i | (i << 8) | (i << 16) | (i << 24));
    }
    cipher = CryptoJS.RC4.encrypt(cipher, key).ciphertext;
  }
  return cipher;
}

function getEncryptionKeyR2R3R4(r, keyBits, documentId, paddedUserPassword, ownerPasswordEntry, permissions) {
  let key = paddedUserPassword.clone()
    .concat(ownerPasswordEntry)
    .concat(CryptoJS.lib.WordArray.create([lsbFirstWord(permissions)], 4))
    .concat(CryptoJS.lib.WordArray.create(documentId));
  const round = r >= 3 ? 51 : 1;
  for (let i = 0; i < round; i++) {
    key = CryptoJS.MD5(key);
    key.sigBytes = keyBits / 8;
  }
  return key;
}

function getUserPasswordR5(processedUserPassword, generateRandomWordArray) {
  const validationSalt = generateRandomWordArray(8);
  const keySalt = generateRandomWordArray(8);
  return CryptoJS.SHA256(processedUserPassword.clone().concat(validationSalt))
    .concat(validationSalt).concat(keySalt);
}

function getUserEncryptionKeyR5(processedUserPassword, userKeySalt, encryptionKey) {
  const key = CryptoJS.SHA256(processedUserPassword.clone().concat(userKeySalt));
  const options = {
    mode: CryptoJS.mode.CBC,
    padding: CryptoJS.pad.NoPadding,
    iv: CryptoJS.lib.WordArray.create(null, 16)
  };
  return CryptoJS.AES.encrypt(encryptionKey, key, options).ciphertext;
}

function getOwnerPasswordR5(processedOwnerPassword, userPasswordEntry, generateRandomWordArray) {
  const validationSalt = generateRandomWordArray(8);
  const keySalt = generateRandomWordArray(8);
  return CryptoJS.SHA256(processedOwnerPassword.clone().concat(validationSalt).concat(userPasswordEntry))
    .concat(validationSalt).concat(keySalt);
}

function getOwnerEncryptionKeyR5(processedOwnerPassword, ownerKeySalt, userPasswordEntry, encryptionKey) {
  const key = CryptoJS.SHA256(processedOwnerPassword.clone().concat(ownerKeySalt).concat(userPasswordEntry));
  const options = {
    mode: CryptoJS.mode.CBC,
    padding: CryptoJS.pad.NoPadding,
    iv: CryptoJS.lib.WordArray.create(null, 16)
  };
  return CryptoJS.AES.encrypt(encryptionKey, key, options).ciphertext;
}

function getEncryptionKeyR5(generateRandomWordArray) {
  return generateRandomWordArray(32);
}

function getEncryptedPermissionsR5(permissions, encryptionKey, generateRandomWordArray) {
  const cipher = CryptoJS.lib.WordArray.create([lsbFirstWord(permissions), 0xffffffff, 0x54616462], 12)
    .concat(generateRandomWordArray(4));
  const options = {
    mode: CryptoJS.mode.ECB,
    padding: CryptoJS.pad.NoPadding
  };
  return CryptoJS.AES.encrypt(cipher, encryptionKey, options).ciphertext;
}

function processPasswordR2R3R4(password = '') {
  const out = new Buffer(32);
  const length = password.length;
  let index = 0;
  while (index < length && index < 32) {
    const code = password.charCodeAt(index);
    if (code > 0xff) {
      throw new Error('Password contains one or more invalid characters.');
    }
    out[index] = code;
    index++;
  }
  while (index < 32) {
    out[index] = PASSWORD_PADDING[index - length];
    index++;
  }
  return CryptoJS.lib.WordArray.create(out);
}

function processPasswordR5(password = '') {
  password = unescape(encodeURIComponent(saslprep(password)));
  const length = Math.min(127, password.length);
  const out = new Buffer(length);

  for (let i = 0; i < length; i++) {
    out[i] = password.charCodeAt(i);
  }

  return CryptoJS.lib.WordArray.create(out);
}

function lsbFirstWord(data) {
  return ((data & 0xff) << 24) | ((data & 0xff00) << 8) | ((data >> 8) & 0xff00) | ((data >> 24) & 0xff);
}

function wordArrayToBuffer(wordArray) {
  const byteArray = [];
  for (let i = 0; i < wordArray.sigBytes; i++) {
    byteArray.push((wordArray.words[Math.floor(i / 4)] >> (8 * (3 - i % 4))) & 0xff);
  }
  return Buffer.from(byteArray);
}

const PASSWORD_PADDING = [
  0x28, 0xbf, 0x4e, 0x5e, 0x4e, 0x75, 0x8a, 0x41, 0x64, 0x00, 0x4e, 0x56, 0xff, 0xfa, 0x01, 0x08,
  0x2e, 0x2e, 0x00, 0xb6, 0xd0, 0x68, 0x3e, 0x80, 0x2f, 0x0c, 0xa9, 0xfe, 0x64, 0x53, 0x69, 0x7a
];

export default PDFSecurity;