import StringBuilder from '../../util/StringBuilder';
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import HighLevelEncoder from './HighLevelEncoder';
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import { C40_ENCODATION, LATCH_TO_C40, ASCII_ENCODATION, C40_UNLATCH, } from './constants';
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export class C40Encoder {
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getEncodingMode() {
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return C40_ENCODATION;
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}
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encodeMaximal(context) {
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const buffer = new StringBuilder();
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let lastCharSize = 0;
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let backtrackStartPosition = context.pos;
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let backtrackBufferLength = 0;
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while (context.hasMoreCharacters()) {
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const c = context.getCurrentChar();
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context.pos++;
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lastCharSize = this.encodeChar(c, buffer);
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if (buffer.length() % 3 === 0) {
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backtrackStartPosition = context.pos;
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backtrackBufferLength = buffer.length();
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}
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}
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if (backtrackBufferLength !== buffer.length()) {
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const unwritten = Math.floor((buffer.length() / 3) * 2);
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const curCodewordCount = Math.floor(context.getCodewordCount() + unwritten + 1); // +1 for the latch to C40
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context.updateSymbolInfo(curCodewordCount);
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const available = context.getSymbolInfo().getDataCapacity() - curCodewordCount;
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const rest = Math.floor(buffer.length() % 3);
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if ((rest === 2 && available !== 2) ||
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(rest === 1 && (lastCharSize > 3 || available !== 1))) {
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// buffer.setLength(backtrackBufferLength);
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context.pos = backtrackStartPosition;
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}
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}
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if (buffer.length() > 0) {
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context.writeCodeword(LATCH_TO_C40);
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}
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this.handleEOD(context, buffer);
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}
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encode(context) {
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// step C
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const buffer = new StringBuilder();
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while (context.hasMoreCharacters()) {
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const c = context.getCurrentChar();
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context.pos++;
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let lastCharSize = this.encodeChar(c, buffer);
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const unwritten = Math.floor(buffer.length() / 3) * 2;
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const curCodewordCount = context.getCodewordCount() + unwritten;
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context.updateSymbolInfo(curCodewordCount);
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const available = context.getSymbolInfo().getDataCapacity() - curCodewordCount;
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if (!context.hasMoreCharacters()) {
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// Avoid having a single C40 value in the last triplet
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const removed = new StringBuilder();
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if (buffer.length() % 3 === 2 && available !== 2) {
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lastCharSize = this.backtrackOneCharacter(context, buffer, removed, lastCharSize);
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}
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while (buffer.length() % 3 === 1 &&
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(lastCharSize > 3 || available !== 1)) {
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lastCharSize = this.backtrackOneCharacter(context, buffer, removed, lastCharSize);
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}
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break;
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}
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const count = buffer.length();
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if (count % 3 === 0) {
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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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}
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this.handleEOD(context, buffer);
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}
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backtrackOneCharacter(context, buffer, removed, lastCharSize) {
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const count = buffer.length();
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const test = buffer.toString().substring(0, count - lastCharSize);
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buffer.setLengthToZero();
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buffer.append(test);
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// buffer.delete(count - lastCharSize, count);
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/*for (let i = count - lastCharSize; i < count; i++) {
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buffer.deleteCharAt(i);
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}*/
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context.pos--;
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const c = context.getCurrentChar();
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lastCharSize = this.encodeChar(c, removed);
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context.resetSymbolInfo(); // Deal with possible reduction in symbol size
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return lastCharSize;
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}
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writeNextTriplet(context, buffer) {
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context.writeCodewords(this.encodeToCodewords(buffer.toString()));
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const test = buffer.toString().substring(3);
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buffer.setLengthToZero();
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buffer.append(test);
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// buffer.delete(0, 3);
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/*for (let i = 0; i < 3; i++) {
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buffer.deleteCharAt(i);
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}*/
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}
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/**
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* Handle "end of data" situations
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*
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* @param context the encoder context
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* @param buffer the buffer with the remaining encoded characters
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*/
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handleEOD(context, buffer) {
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const unwritten = Math.floor((buffer.length() / 3) * 2);
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const rest = buffer.length() % 3;
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const curCodewordCount = context.getCodewordCount() + unwritten;
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context.updateSymbolInfo(curCodewordCount);
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const available = context.getSymbolInfo().getDataCapacity() - curCodewordCount;
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if (rest === 2) {
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buffer.append('\0'); // Shift 1
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while (buffer.length() >= 3) {
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this.writeNextTriplet(context, buffer);
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}
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if (context.hasMoreCharacters()) {
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context.writeCodeword(C40_UNLATCH);
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}
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}
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else if (available === 1 && rest === 1) {
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while (buffer.length() >= 3) {
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this.writeNextTriplet(context, buffer);
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}
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if (context.hasMoreCharacters()) {
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context.writeCodeword(C40_UNLATCH);
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}
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// else no unlatch
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context.pos--;
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}
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else if (rest === 0) {
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while (buffer.length() >= 3) {
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this.writeNextTriplet(context, buffer);
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}
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if (available > 0 || context.hasMoreCharacters()) {
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context.writeCodeword(C40_UNLATCH);
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}
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}
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else {
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throw new Error('Unexpected case. Please report!');
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}
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context.signalEncoderChange(ASCII_ENCODATION);
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}
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encodeChar(c, sb) {
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if (c === ' '.charCodeAt(0)) {
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sb.append(0o3);
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return 1;
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}
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if (c >= '0'.charCodeAt(0) && c <= '9'.charCodeAt(0)) {
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sb.append(c - 48 + 4);
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return 1;
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}
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if (c >= 'A'.charCodeAt(0) && c <= 'Z'.charCodeAt(0)) {
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sb.append(c - 65 + 14);
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return 1;
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}
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if (c < ' '.charCodeAt(0)) {
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sb.append(0o0); // Shift 1 Set
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sb.append(c);
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return 2;
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}
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if (c <= '/'.charCodeAt(0)) {
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sb.append(0o1); // Shift 2 Set
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sb.append(c - 33);
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return 2;
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}
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if (c <= '@'.charCodeAt(0)) {
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sb.append(0o1); // Shift 2 Set
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sb.append(c - 58 + 15);
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return 2;
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}
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if (c <= '_'.charCodeAt(0)) {
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sb.append(0o1); // Shift 2 Set
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sb.append(c - 91 + 22);
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return 2;
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}
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if (c <= 127) {
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sb.append(0o2); // Shift 3 Set
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sb.append(c - 96);
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return 2;
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}
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sb.append(`${0o1}\u001e`); // Shift 2, Upper Shift
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let len = 2;
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len += this.encodeChar(c - 128, sb);
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return len;
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}
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encodeToCodewords(sb) {
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const v = 1600 * sb.charCodeAt(0) + 40 * sb.charCodeAt(1) + sb.charCodeAt(2) + 1;
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const cw1 = v / 256;
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const cw2 = v % 256;
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const result = new StringBuilder();
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result.append(cw1);
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result.append(cw2);
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return result.toString();
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}
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}
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