import gb2312 from './gb2312.json'

export class StringBase64 {
  static ToBase64_gb2312(str: string): string {
    let bin = this.toGB2312Bytes(str || '')
    let str64 = this.encode(bin)
    return str64
  }

  static _table = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
    'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
    'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
    'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/']

  /** 将二进制转换成base64 */
  static encode(bin: number[]): string {
    let codes = []
    let un = 0
    un = bin.length % 3
    if (un == 1)
      bin.push(0, 0)
    else if (un == 2)
      bin.push(0)
    for (let i = 2; i < bin.length; i += 3) {
      let c = bin[i - 2] << 16
      c |= bin[i - 1] << 8
      c |= bin[i]
      codes.push(this._table[c >> 18 & 0x3F])
      codes.push(this._table[c >> 12 & 0x3F])
      codes.push(this._table[c >> 6 & 0x3F])
      codes.push(this._table[c & 0x3F])
    }
    if (un >= 1) {
      codes[codes.length - 1] = '='
      bin.pop()
    }
    if (un == 1) {
      codes[codes.length - 2] = '='
      bin.pop()
    }
    return codes.join('')
  }

  /** 将utf8 转成gb2312字符串 */
  static toGb2312String(str1: string): string {
    let substr = ''
    let a = ''
    let b = ''
    let c = ''
    let i = -1
    i = str1.indexOf('%')
    if (i == -1) {
      return str1
    }
    while (i != -1) {
      if (i < 3) {
        substr = substr + str1.substr(0, i - 1)
        str1 = str1.substr(i + 1, str1.length - i)
        a = str1.substr(0, 2)
        str1 = str1.substr(2, str1.length - 2)
        if ((Number.parseInt(`0x${a}`) & 0x80) == 0) {
          substr = substr + String.fromCharCode(Number.parseInt(`0x${a}`))
        }
        else if ((Number.parseInt(`0x${a}`) & 0xE0) == 0xC0) { // two byte
          b = str1.substr(1, 2)
          str1 = str1.substr(3, str1.length - 3)
          let widechar = (Number.parseInt(`0x${a}`) & 0x1F) << 6
          widechar = widechar | (Number.parseInt(`0x${b}`) & 0x3F)
          substr = substr + String.fromCharCode(widechar)
        }
        else {
          b = str1.substr(1, 2)
          str1 = str1.substr(3, str1.length - 3)
          c = str1.substr(1, 2)
          str1 = str1.substr(3, str1.length - 3)
          let widechar = (Number.parseInt(`0x${a}`) & 0x0F) << 12
          widechar = widechar | ((Number.parseInt(`0x${b}`) & 0x3F) << 6)
          widechar = widechar | (Number.parseInt(`0x${c}`) & 0x3F)
          substr = substr + String.fromCharCode(widechar)
        }
      }
      else {
        substr = substr + str1.substring(0, i)
        str1 = str1.substring(i)
      }
      i = str1.indexOf('%')
    }

    return substr + str1
  }

  private static _unicode2gb
  static getUnicode2gb() {
    if (this._unicode2gb == null) {
      this._unicode2gb = gb2312
    }
    return this._unicode2gb
  }

  static toGB2312Bytes(str: string): number[] {
    let unicode2gb = this.getUnicode2gb()
    let res = []; let len = str.length
    for (let i = 0; i < len; i++) {
      let code = str.charCodeAt(i)
      if (code <= 0x007F) {
        res.push(code)
      }
      else {
        let hex = unicode2gb[`0x${code.toString(16).toUpperCase()}`]
        let gb = Number(hex)
        if (Number.isNaN(gb))
          gb = Number('0xA1F5')

        let arr = []
        while (gb > 0) {
          arr.push(gb & 0xFF)
          gb >>= 8
        }
        while (arr.length > 0) res.push(arr.pop())
      }
    }
    return res
  }

  static fromGB2312Bytes(gb2312Bytes: number[]): string {
    let unicode2gb = this.getUnicode2gb()
    let res = []
    // var i = 0
    for (let i = 0; i < gb2312Bytes.length; i++) {
      let code = gb2312Bytes[i]
      if (code < 0xA1 || code > 0xFE || i + 1 == gb2312Bytes.length) {
        res.push(String.fromCharCode(code))
        continue
      }
      let c2 = gb2312Bytes[i + 1]
      if (code < 0xA1 || code > 0xFE) {
        res.push(String.fromCharCode(code))
        continue
      }
      let g = c2 | code << 8

      c2 = Number(unicode2gb[`0x${g.toString(16).toUpperCase()}`])
      if (typeof c2 == 'undefined') {
        res.push(String.fromCharCode(code))
        continue
      }
      res.push(String.fromCharCode(c2))
      i++
    }
    return res.join('')
  }
}