/* Copyright 2012 Mozilla Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/* eslint-disable no-var */

import { DecodeStream } from "./stream.js";

var AsciiHexStream = (function AsciiHexStreamClosure() {
  // eslint-disable-next-line no-shadow
  function AsciiHexStream(str, maybeLength) {
    this.str = str;
    this.dict = str.dict;

    this.firstDigit = -1;

    // Most streams increase in size when decoded, but AsciiHex streams shrink
    // by 50%.
    if (maybeLength) {
      maybeLength = 0.5 * maybeLength;
    }
    DecodeStream.call(this, maybeLength);
  }

  AsciiHexStream.prototype = Object.create(DecodeStream.prototype);

  AsciiHexStream.prototype.readBlock = function AsciiHexStream_readBlock() {
    var UPSTREAM_BLOCK_SIZE = 8000;
    var bytes = this.str.getBytes(UPSTREAM_BLOCK_SIZE);
    if (!bytes.length) {
      this.eof = true;
      return;
    }

    var maxDecodeLength = (bytes.length + 1) >> 1;
    var buffer = this.ensureBuffer(this.bufferLength + maxDecodeLength);
    var bufferLength = this.bufferLength;

    var firstDigit = this.firstDigit;
    for (var i = 0, ii = bytes.length; i < ii; i++) {
      var ch = bytes[i],
        digit;
      if (ch >= /* '0' = */ 0x30 && ch <= /* '9' = */ 0x39) {
        digit = ch & 0x0f;
      } else if (
        (ch >= /* 'A' = */ 0x41 && ch <= /* 'Z' = */ 0x46) ||
        (ch >= /* 'a' = */ 0x61 && ch <= /* 'z' = */ 0x66)
      ) {
        digit = (ch & 0x0f) + 9;
      } else if (ch === /* '>' = */ 0x3e) {
        this.eof = true;
        break;
      } else {
        // Probably whitespace, ignoring.
        continue;
      }
      if (firstDigit < 0) {
        firstDigit = digit;
      } else {
        buffer[bufferLength++] = (firstDigit << 4) | digit;
        firstDigit = -1;
      }
    }
    if (firstDigit >= 0 && this.eof) {
      // incomplete byte
      buffer[bufferLength++] = firstDigit << 4;
      firstDigit = -1;
    }
    this.firstDigit = firstDigit;
    this.bufferLength = bufferLength;
  };

  return AsciiHexStream;
})();

export { AsciiHexStream };