module.exports = function convert_cyr_string(str, from, to) {
  //  discuss at: https://locutus.io/php/convert_cyr_string/
  // original by: Brett Zamir (https://brett-zamir.me)
  //      note 1: Assumes and converts to Unicode strings with character
  //      note 1: code equivalents of the same numbers as in the from or
  //      note 1: target character set; Note that neither the input or output
  //      note 1: should be treated as actual Unicode, since the PHP function
  //      note 1: this is original by does not either
  //      note 1: One could easily represent (or convert the results) of a
  //      note 1: string form as arrays of code points instead but since JavaScript
  //      note 1: currently has no clear binary data type, we chose to use strings
  //      note 1: as in PHP
  //   example 1: convert_cyr_string(String.fromCharCode(214), 'k', 'w').charCodeAt(0) === 230; // Char. 214 of KOI8-R gives equivalent number value 230 in win1251
  //   returns 1: true

  const _cyrWin1251 = [
    0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30,
    31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59,
    60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88,
    89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113,
    114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46,
    46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 154, 174, 190, 46, 159, 189, 46,
    46, 179, 191, 180, 157, 46, 46, 156, 183, 46, 46, 182, 166, 173, 46, 46, 158, 163, 152, 164, 155, 46, 46, 46, 167,
    225, 226, 247, 231, 228, 229, 246, 250, 233, 234, 235, 236, 237, 238, 239, 240, 242, 243, 244, 245, 230, 232, 227,
    254, 251, 253, 255, 249, 248, 252, 224, 241, 193, 194, 215, 199, 196, 197, 214, 218, 201, 202, 203, 204, 205, 206,
    207, 208, 210, 211, 212, 213, 198, 200, 195, 222, 219, 221, 223, 217, 216, 220, 192, 209, 0, 1, 2, 3, 4, 5, 6, 7, 8,
    9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37,
    38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66,
    67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95,
    96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119,
    120, 121, 122, 123, 124, 125, 126, 127, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32,
    32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 184, 186, 32, 179, 191, 32, 32, 32, 32, 32, 180,
    162, 32, 32, 32, 32, 168, 170, 32, 178, 175, 32, 32, 32, 32, 32, 165, 161, 169, 254, 224, 225, 246, 228, 229, 244,
    227, 245, 232, 233, 234, 235, 236, 237, 238, 239, 255, 240, 241, 242, 243, 230, 226, 252, 251, 231, 248, 253, 249,
    247, 250, 222, 192, 193, 214, 196, 197, 212, 195, 213, 200, 201, 202, 203, 204, 205, 206, 207, 223, 208, 209, 210,
    211, 198, 194, 220, 219, 199, 216, 221, 217, 215, 218,
  ]
  const _cyrCp866 = [
    0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30,
    31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59,
    60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88,
    89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113,
    114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 225, 226, 247, 231, 228, 229, 246, 250, 233,
    234, 235, 236, 237, 238, 239, 240, 242, 243, 244, 245, 230, 232, 227, 254, 251, 253, 255, 249, 248, 252, 224, 241,
    193, 194, 215, 199, 196, 197, 214, 218, 201, 202, 203, 204, 205, 206, 207, 208, 35, 35, 35, 124, 124, 124, 124, 43,
    43, 124, 124, 43, 43, 43, 43, 43, 43, 45, 45, 124, 45, 43, 124, 124, 43, 43, 45, 45, 124, 45, 43, 45, 45, 45, 45,
    43, 43, 43, 43, 43, 43, 43, 43, 35, 35, 124, 124, 35, 210, 211, 212, 213, 198, 200, 195, 222, 219, 221, 223, 217,
    216, 220, 192, 209, 179, 163, 180, 164, 183, 167, 190, 174, 32, 149, 158, 32, 152, 159, 148, 154, 0, 1, 2, 3, 4, 5,
    6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35,
    36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64,
    65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93,
    94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117,
    118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32,
    32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 205, 186, 213, 241, 243, 201, 32, 245, 187, 212,
    211, 200, 190, 32, 247, 198, 199, 204, 181, 240, 242, 185, 32, 244, 203, 207, 208, 202, 216, 32, 246, 32, 238, 160,
    161, 230, 164, 165, 228, 163, 229, 168, 169, 170, 171, 172, 173, 174, 175, 239, 224, 225, 226, 227, 166, 162, 236,
    235, 167, 232, 237, 233, 231, 234, 158, 128, 129, 150, 132, 133, 148, 131, 149, 136, 137, 138, 139, 140, 141, 142,
    143, 159, 144, 145, 146, 147, 134, 130, 156, 155, 135, 152, 157, 153, 151, 154,
  ]
  const _cyrIso88595 = [
    0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30,
    31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59,
    60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88,
    89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113,
    114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32,
    32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 179, 32, 32, 32, 32, 32, 32,
    32, 32, 32, 32, 32, 32, 32, 32, 225, 226, 247, 231, 228, 229, 246, 250, 233, 234, 235, 236, 237, 238, 239, 240, 242,
    243, 244, 245, 230, 232, 227, 254, 251, 253, 255, 249, 248, 252, 224, 241, 193, 194, 215, 199, 196, 197, 214, 218,
    201, 202, 203, 204, 205, 206, 207, 208, 210, 211, 212, 213, 198, 200, 195, 222, 219, 221, 223, 217, 216, 220, 192,
    209, 32, 163, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,
    14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42,
    43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71,
    72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100,
    101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123,
    124, 125, 126, 127, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32,
    32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 241, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 161,
    32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 238, 208, 209, 230, 212, 213, 228, 211, 229, 216, 217, 218, 219,
    220, 221, 222, 223, 239, 224, 225, 226, 227, 214, 210, 236, 235, 215, 232, 237, 233, 231, 234, 206, 176, 177, 198,
    180, 181, 196, 179, 197, 184, 185, 186, 187, 188, 189, 190, 191, 207, 192, 193, 194, 195, 182, 178, 204, 203, 183,
    200, 205, 201, 199, 202,
  ]
  const _cyrMac = [
    0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30,
    31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59,
    60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88,
    89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113,
    114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 225, 226, 247, 231, 228, 229, 246, 250, 233,
    234, 235, 236, 237, 238, 239, 240, 242, 243, 244, 245, 230, 232, 227, 254, 251, 253, 255, 249, 248, 252, 224, 241,
    160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182,
    183, 184, 185, 186, 187, 188, 189, 190, 191, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141,
    142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 179, 163, 209, 193, 194, 215, 199, 196,
    197, 214, 218, 201, 202, 203, 204, 205, 206, 207, 208, 210, 211, 212, 213, 198, 200, 195, 222, 219, 221, 223, 217,
    216, 220, 192,

    255, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29,
    30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54,

    55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83,
    84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109,
    110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 192, 193, 194, 195, 196,
    197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219,
    220, 221, 222, 223, 160, 161, 162, 222, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178,
    221, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 254, 224, 225, 246, 228, 229, 244, 227, 245, 232,
    233, 234, 235, 236, 237, 238, 239, 223, 240, 241,

    242, 243, 230, 226, 252, 251, 231, 248, 253, 249, 247, 250, 158, 128, 129, 150, 132, 133, 148, 131, 149, 136, 137,
    138, 139, 140, 141, 142, 143, 159, 144, 145, 146, 147, 134, 130, 156, 155, 135, 152, 157, 153, 151, 154,
  ]

  let fromTable = null
  let toTable = null
  let tmp
  let i = 0
  let retStr = ''

  switch (from.toUpperCase()) {
    case 'W':
      fromTable = _cyrWin1251
      break
    case 'A':
    case 'D':
      fromTable = _cyrCp866
      break
    case 'I':
      fromTable = _cyrIso88595
      break
    case 'M':
      fromTable = _cyrMac
      break
    case 'K':
      break
    default:
      // Can we throw a warning instead? That would be more in line with PHP
      throw new Error('Unknown source charset: ' + fromTable)
  }

  switch (to.toUpperCase()) {
    case 'W':
      toTable = _cyrWin1251
      break
    case 'A':
    case 'D':
      toTable = _cyrCp866
      break
    case 'I':
      toTable = _cyrIso88595
      break
    case 'M':
      toTable = _cyrMac
      break
    case 'K':
      break
    default:
      // Can we throw a warning instead? That would be more in line with PHP
      throw new Error('Unknown destination charset: ' + toTable)
  }

  if (!str) {
    return str
  }

  for (i = 0; i < str.length; i++) {
    tmp = fromTable === null ? str.charAt(i) : String.fromCharCode(fromTable[str.charAt(i).charCodeAt(0)])

    retStr += toTable === null ? tmp : String.fromCharCode(toTable[tmp.charCodeAt(0) + 256])
  }

  return retStr
}