import StringUtils from '../../common/StringUtils';
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import StringBuilder from '../../util/StringBuilder';
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import HighLevelEncoder from './HighLevelEncoder';
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import { BASE256_ENCODATION, ASCII_ENCODATION } from './constants';
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export class Base256Encoder {
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getEncodingMode() {
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return BASE256_ENCODATION;
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}
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encode(context) {
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const buffer = new StringBuilder();
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buffer.append(0o0); // Initialize length field
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while (context.hasMoreCharacters()) {
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const c = context.getCurrentChar();
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buffer.append(c);
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context.pos++;
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const newMode = HighLevelEncoder.lookAheadTest(context.getMessage(), context.pos, this.getEncodingMode());
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if (newMode !== this.getEncodingMode()) {
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// Return to ASCII encodation, which will actually handle latch to new mode
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context.signalEncoderChange(ASCII_ENCODATION);
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break;
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}
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}
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const dataCount = buffer.length() - 1;
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const lengthFieldSize = 1;
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const currentSize = context.getCodewordCount() + dataCount + lengthFieldSize;
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context.updateSymbolInfo(currentSize);
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const mustPad = context.getSymbolInfo().getDataCapacity() - currentSize > 0;
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if (context.hasMoreCharacters() || mustPad) {
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if (dataCount <= 249) {
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buffer.setCharAt(0, StringUtils.getCharAt(dataCount));
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}
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else if (dataCount <= 1555) {
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buffer.setCharAt(0, StringUtils.getCharAt(Math.floor(dataCount / 250) + 249));
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buffer.insert(1, StringUtils.getCharAt(dataCount % 250));
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}
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else {
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throw new Error('Message length not in valid ranges: ' + dataCount);
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}
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}
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for (let i = 0, c = buffer.length(); i < c; i++) {
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context.writeCodeword(this.randomize255State(buffer.charAt(i).charCodeAt(0), context.getCodewordCount() + 1));
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}
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}
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randomize255State(ch, codewordPosition) {
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const pseudoRandom = ((149 * codewordPosition) % 255) + 1;
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const tempVariable = ch + pseudoRandom;
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if (tempVariable <= 255) {
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return tempVariable;
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}
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else {
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return tempVariable - 256;
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}
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}
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}
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