src/utils/cea-608-parser.ts

import OutputFilter from './output-filter';
 
/**
 *
 * This code was ported from the dash.js project at:
 *   https://github.com/Dash-Industry-Forum/dash.js/blob/development/externals/cea608-parser.js
 *   https://github.com/Dash-Industry-Forum/dash.js/commit/8269b26a761e0853bb21d78780ed945144ecdd4d#diff-71bc295a2d6b6b7093a1d3290d53a4b2
 *
 * The original copyright appears below:
 *
 * The copyright in this software is being made available under the BSD License,
 * included below. This software may be subject to other third party and contributor
 * rights, including patent rights, and no such rights are granted under this license.
 *
 * Copyright (c) 2015-2016, DASH Industry Forum.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *  1. Redistributions of source code must retain the above copyright notice, this
 *  list of conditions and the following disclaimer.
 *  * Redistributions in binary form must reproduce the above copyright notice,
 *  this list of conditions and the following disclaimer in the documentation and/or
 *  other materials provided with the distribution.
 *  2. Neither the name of Dash Industry Forum nor the names of its
 *  contributors may be used to endorse or promote products derived from this software
 *  without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS AS IS AND ANY
 *  EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 *  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 *  IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 *  INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 *  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 *  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 *  WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 *  POSSIBILITY OF SUCH DAMAGE.
 */
/**
 *  Exceptions from regular ASCII. CodePoints are mapped to UTF-16 codes
 */
 
const specialCea608CharsCodes = {
  0x2a: 0xe1, // lowercase a, acute accent
  0x5c: 0xe9, // lowercase e, acute accent
  0x5e: 0xed, // lowercase i, acute accent
  0x5f: 0xf3, // lowercase o, acute accent
  0x60: 0xfa, // lowercase u, acute accent
  0x7b: 0xe7, // lowercase c with cedilla
  0x7c: 0xf7, // division symbol
  0x7d: 0xd1, // uppercase N tilde
  0x7e: 0xf1, // lowercase n tilde
  0x7f: 0x2588, // Full block
  // THIS BLOCK INCLUDES THE 16 EXTENDED (TWO-BYTE) LINE 21 CHARACTERS
  // THAT COME FROM HI BYTE=0x11 AND LOW BETWEEN 0x30 AND 0x3F
  // THIS MEANS THAT \x50 MUST BE ADDED TO THE VALUES
  0x80: 0xae, // Registered symbol (R)
  0x81: 0xb0, // degree sign
  0x82: 0xbd, // 1/2 symbol
  0x83: 0xbf, // Inverted (open) question mark
  0x84: 0x2122, // Trademark symbol (TM)
  0x85: 0xa2, // Cents symbol
  0x86: 0xa3, // Pounds sterling
  0x87: 0x266a, // Music 8'th note
  0x88: 0xe0, // lowercase a, grave accent
  0x89: 0x20, // transparent space (regular)
  0x8a: 0xe8, // lowercase e, grave accent
  0x8b: 0xe2, // lowercase a, circumflex accent
  0x8c: 0xea, // lowercase e, circumflex accent
  0x8d: 0xee, // lowercase i, circumflex accent
  0x8e: 0xf4, // lowercase o, circumflex accent
  0x8f: 0xfb, // lowercase u, circumflex accent
  // THIS BLOCK INCLUDES THE 32 EXTENDED (TWO-BYTE) LINE 21 CHARACTERS
  // THAT COME FROM HI BYTE=0x12 AND LOW BETWEEN 0x20 AND 0x3F
  0x90: 0xc1, // capital letter A with acute
  0x91: 0xc9, // capital letter E with acute
  0x92: 0xd3, // capital letter O with acute
  0x93: 0xda, // capital letter U with acute
  0x94: 0xdc, // capital letter U with diaresis
  0x95: 0xfc, // lowercase letter U with diaeresis
  0x96: 0x2018, // opening single quote
  0x97: 0xa1, // inverted exclamation mark
  0x98: 0x2a, // asterisk
  0x99: 0x2019, // closing single quote
  0x9a: 0x2501, // box drawings heavy horizontal
  0x9b: 0xa9, // copyright sign
  0x9c: 0x2120, // Service mark
  0x9d: 0x2022, // (round) bullet
  0x9e: 0x201c, // Left double quotation mark
  0x9f: 0x201d, // Right double quotation mark
  0xa0: 0xc0, // uppercase A, grave accent
  0xa1: 0xc2, // uppercase A, circumflex
  0xa2: 0xc7, // uppercase C with cedilla
  0xa3: 0xc8, // uppercase E, grave accent
  0xa4: 0xca, // uppercase E, circumflex
  0xa5: 0xcb, // capital letter E with diaresis
  0xa6: 0xeb, // lowercase letter e with diaresis
  0xa7: 0xce, // uppercase I, circumflex
  0xa8: 0xcf, // uppercase I, with diaresis
  0xa9: 0xef, // lowercase i, with diaresis
  0xaa: 0xd4, // uppercase O, circumflex
  0xab: 0xd9, // uppercase U, grave accent
  0xac: 0xf9, // lowercase u, grave accent
  0xad: 0xdb, // uppercase U, circumflex
  0xae: 0xab, // left-pointing double angle quotation mark
  0xaf: 0xbb, // right-pointing double angle quotation mark
  // THIS BLOCK INCLUDES THE 32 EXTENDED (TWO-BYTE) LINE 21 CHARACTERS
  // THAT COME FROM HI BYTE=0x13 AND LOW BETWEEN 0x20 AND 0x3F
  0xb0: 0xc3, // Uppercase A, tilde
  0xb1: 0xe3, // Lowercase a, tilde
  0xb2: 0xcd, // Uppercase I, acute accent
  0xb3: 0xcc, // Uppercase I, grave accent
  0xb4: 0xec, // Lowercase i, grave accent
  0xb5: 0xd2, // Uppercase O, grave accent
  0xb6: 0xf2, // Lowercase o, grave accent
  0xb7: 0xd5, // Uppercase O, tilde
  0xb8: 0xf5, // Lowercase o, tilde
  0xb9: 0x7b, // Open curly brace
  0xba: 0x7d, // Closing curly brace
  0xbb: 0x5c, // Backslash
  0xbc: 0x5e, // Caret
  0xbd: 0x5f, // Underscore
  0xbe: 0x7c, // Pipe (vertical line)
  0xbf: 0x223c, // Tilde operator
  0xc0: 0xc4, // Uppercase A, umlaut
  0xc1: 0xe4, // Lowercase A, umlaut
  0xc2: 0xd6, // Uppercase O, umlaut
  0xc3: 0xf6, // Lowercase o, umlaut
  0xc4: 0xdf, // Esszett (sharp S)
  0xc5: 0xa5, // Yen symbol
  0xc6: 0xa4, // Generic currency sign
  0xc7: 0x2503, // Box drawings heavy vertical
  0xc8: 0xc5, // Uppercase A, ring
  0xc9: 0xe5, // Lowercase A, ring
  0xca: 0xd8, // Uppercase O, stroke
  0xcb: 0xf8, // Lowercase o, strok
  0xcc: 0x250f, // Box drawings heavy down and right
  0xcd: 0x2513, // Box drawings heavy down and left
  0xce: 0x2517, // Box drawings heavy up and right
  0xcf: 0x251b // Box drawings heavy up and left
};
 
/**
 * Utils
 */
const getCharForByte = function (byte: number) {
  let charCode = byte;
  if (specialCea608CharsCodes.hasOwnProperty(byte)) {
    charCode = specialCea608CharsCodes[byte];
  }
 
  return String.fromCharCode(charCode);
};
 
const NR_ROWS = 15;
const NR_COLS = 100;
// Tables to look up row from PAC data
const rowsLowCh1 = { 0x11: 1, 0x12: 3, 0x15: 5, 0x16: 7, 0x17: 9, 0x10: 11, 0x13: 12, 0x14: 14 };
const rowsHighCh1 = { 0x11: 2, 0x12: 4, 0x15: 6, 0x16: 8, 0x17: 10, 0x13: 13, 0x14: 15 };
const rowsLowCh2 = { 0x19: 1, 0x1A: 3, 0x1D: 5, 0x1E: 7, 0x1F: 9, 0x18: 11, 0x1B: 12, 0x1C: 14 };
const rowsHighCh2 = { 0x19: 2, 0x1A: 4, 0x1D: 6, 0x1E: 8, 0x1F: 10, 0x1B: 13, 0x1C: 15 };
 
const backgroundColors = ['white', 'green', 'blue', 'cyan', 'red', 'yellow', 'magenta', 'black', 'transparent'];
 
enum VerboseFilter {
  ERROR = 0,
  TEXT = 1,
  WARNING = 2,
  INFO = 2,
  DEBUG = 3,
  DATA = 3,
}
 
/**
 * Simple logger class to be able to write with time-stamps and filter on level.
 */
const logger: {
  verboseFilter: {
    'DATA': VerboseFilter.DATA;
    'DEBUG': VerboseFilter.DEBUG;
    'INFO': VerboseFilter.INFO;
    'WARNING': VerboseFilter.WARNING;
    'TEXT': VerboseFilter.TEXT;
    'ERROR': VerboseFilter.ERROR;
  },
  time: number | null
  verboseLevel: VerboseFilter,
  setTime: (newTime: number | null) => void,
  log: (severity: keyof typeof VerboseFilter, msg: string) => void,
} = {
  verboseFilter: { DATA: 3, DEBUG: 3, INFO: 2, WARNING: 2, TEXT: 1, ERROR: 0 },
  time: null,
  verboseLevel: 0, // Only write errors
  setTime: function (newTime) {
    this.time = newTime;
  },
  log: function (severity, msg) {
    const minLevel = this.verboseFilter[severity];
    if (this.verboseLevel >= minLevel) {
      console.log(this.time + ' [' + severity + '] ' + msg);
    }
  }
};
 
const numArrayToHexArray = function (numArray: number[]): string[] {
  const hexArray: string[] = [];
  for (let j = 0; j < numArray.length; j++) {
    hexArray.push(numArray[j].toString(16));
  }
 
  return hexArray;
};
 
type PenStyles = {
  foreground: string | null,
  underline: boolean,
  italics: boolean,
  background: string,
  flash: boolean,
};
 
class PenState {
  public foreground: string;
  public underline: boolean;
  public italics: boolean;
  public background: string;
  public flash: boolean;
 
  constructor (foreground?: string, underline?: boolean, italics?: boolean, background?: string, flash?: boolean) {
    this.foreground = foreground || 'white';
    this.underline = underline || false;
    this.italics = italics || false;
    this.background = background || 'black';
    this.flash = flash || false;
  }
 
  reset () {
    this.foreground = 'white';
    this.underline = false;
    this.italics = false;
    this.background = 'black';
    this.flash = false;
  }
 
  setStyles (styles: Partial<PenStyles>) {
    const attribs = ['foreground', 'underline', 'italics', 'background', 'flash'];
    for (let i = 0; i < attribs.length; i++) {
      const style = attribs[i];
      if (styles.hasOwnProperty(style)) {
        this[style] = styles[style];
      }
    }
  }
 
  isDefault () {
    return (this.foreground === 'white' && !this.underline && !this.italics &&
      this.background === 'black' && !this.flash);
  }
 
  equals (other: PenState) {
    return ((this.foreground === other.foreground) &&
      (this.underline === other.underline) &&
      (this.italics === other.italics) &&
      (this.background === other.background) &&
      (this.flash === other.flash));
  }
 
  copy (newPenState: PenState) {
    this.foreground = newPenState.foreground;
    this.underline = newPenState.underline;
    this.italics = newPenState.italics;
    this.background = newPenState.background;
    this.flash = newPenState.flash;
  }
 
  toString (): string {
    return ('color=' + this.foreground + ', underline=' + this.underline + ', italics=' + this.italics +
      ', background=' + this.background + ', flash=' + this.flash);
  }
}
 
/**
 * Unicode character with styling and background.
 * @constructor
 */
class StyledUnicodeChar {
  uchar: string;
  penState: PenState;
  constructor (uchar?: string, foreground?: string, underline?: boolean, italics?: boolean, background?: string, flash?: boolean) {
    this.uchar = uchar || ' '; // unicode character
    this.penState = new PenState(foreground, underline, italics, background, flash);
  }
 
  reset () {
    this.uchar = ' ';
    this.penState.reset();
  }
 
  setChar (uchar: string, newPenState: PenState) {
    this.uchar = uchar;
    this.penState.copy(newPenState);
  }
 
  setPenState (newPenState: PenState) {
    this.penState.copy(newPenState);
  }
 
  equals (other: StyledUnicodeChar) {
    return this.uchar === other.uchar && this.penState.equals(other.penState);
  }
 
  copy (newChar: StyledUnicodeChar) {
    this.uchar = newChar.uchar;
    this.penState.copy(newChar.penState);
  }
 
  isEmpty (): boolean {
    return this.uchar === ' ' && this.penState.isDefault();
  }
}
 
/**
 * CEA-608 row consisting of NR_COLS instances of StyledUnicodeChar.
 * @constructor
 */
export class Row {
  public chars: StyledUnicodeChar[];
  public pos: number;
  public currPenState: PenState;
  public cueStartTime?: number;
  constructor () {
    this.chars = [];
    for (let i = 0; i < NR_COLS; i++) {
      this.chars.push(new StyledUnicodeChar());
    }
 
    this.pos = 0;
    this.currPenState = new PenState();
  }
 
  equals (other: Row) {
    let equal = true;
    for (let i = 0; i < NR_COLS; i++) {
      if (!this.chars[i].equals(other.chars[i])) {
        equal = false;
        break;
      }
    }
    return equal;
  }
 
  copy (other: Row) {
    for (let i = 0; i < NR_COLS; i++) {
      this.chars[i].copy(other.chars[i]);
    }
  }
 
  isEmpty (): boolean {
    let empty = true;
    for (let i = 0; i < NR_COLS; i++) {
      if (!this.chars[i].isEmpty()) {
        empty = false;
        break;
      }
    }
    return empty;
  }
 
  /**
   *  Set the cursor to a valid column.
   */
  setCursor (absPos: number) {
    if (this.pos !== absPos) {
      this.pos = absPos;
    }
 
    if (this.pos < 0) {
      logger.log('DEBUG', 'Negative cursor position ' + this.pos);
      this.pos = 0;
    } else if (this.pos > NR_COLS) {
      logger.log('DEBUG', 'Too large cursor position ' + this.pos);
      this.pos = NR_COLS;
    }
  }
 
  /**
   * Move the cursor relative to current position.
   */
  moveCursor (relPos: number) {
    const newPos = this.pos + relPos;
    if (relPos > 1) {
      for (let i = this.pos + 1; i < newPos + 1; i++) {
        this.chars[i].setPenState(this.currPenState);
      }
    }
    this.setCursor(newPos);
  }
 
  /**
   * Backspace, move one step back and clear character.
   */
  backSpace () {
    this.moveCursor(-1);
    this.chars[this.pos].setChar(' ', this.currPenState);
  }
 
  insertChar (byte: number) {
    if (byte >= 0x90) { // Extended char
      this.backSpace();
    }
    const char = getCharForByte(byte);
    if (this.pos >= NR_COLS) {
      logger.log('ERROR', 'Cannot insert ' + byte.toString(16) +
        ' (' + char + ') at position ' + this.pos + '. Skipping it!');
      return;
    }
    this.chars[this.pos].setChar(char, this.currPenState);
    this.moveCursor(1);
  }
 
  clearFromPos (startPos: number) {
    let i: number;
    for (i = startPos; i < NR_COLS; i++) {
      this.chars[i].reset();
    }
  }
 
  clear () {
    this.clearFromPos(0);
    this.pos = 0;
    this.currPenState.reset();
  }
 
  clearToEndOfRow () {
    this.clearFromPos(this.pos);
  }
 
  getTextString () {
    const chars: string[] = [];
    let empty = true;
    for (let i = 0; i < NR_COLS; i++) {
      const char = this.chars[i].uchar;
      if (char !== ' ') {
        empty = false;
      }
 
      chars.push(char);
    }
    if (empty) {
      return '';
    } else {
      return chars.join('');
    }
  }
 
  setPenStyles (styles: Partial<PenStyles>) {
    this.currPenState.setStyles(styles);
    const currChar = this.chars[this.pos];
    currChar.setPenState(this.currPenState);
  }
}
 
/**
 * Keep a CEA-608 screen of 32x15 styled characters
 * @constructor
 */
export class CaptionScreen {
  rows: Row[];
  currRow: number;
  nrRollUpRows: number | null;
  lastOutputScreen: any;
  constructor () {
    this.rows = [];
    for (let i = 0; i < NR_ROWS; i++) {
      this.rows.push(new Row());
    } // Note that we use zero-based numbering (0-14)
 
    this.currRow = NR_ROWS - 1;
    this.nrRollUpRows = null;
    this.lastOutputScreen = null;
    this.reset();
  }
 
  reset () {
    for (let i = 0; i < NR_ROWS; i++) {
      this.rows[i].clear();
    }
 
    this.currRow = NR_ROWS - 1;
  }
 
  equals (other: CaptionScreen): boolean {
    let equal = true;
    for (let i = 0; i < NR_ROWS; i++) {
      if (!this.rows[i].equals(other.rows[i])) {
        equal = false;
        break;
      }
    }
    return equal;
  }
 
  copy (other: CaptionScreen) {
    for (let i = 0; i < NR_ROWS; i++) {
      this.rows[i].copy(other.rows[i]);
    }
  }
 
  isEmpty (): boolean {
    let empty = true;
    for (let i = 0; i < NR_ROWS; i++) {
      if (!this.rows[i].isEmpty()) {
        empty = false;
        break;
      }
    }
    return empty;
  }
 
  backSpace () {
    const row = this.rows[this.currRow];
    row.backSpace();
  }
 
  clearToEndOfRow () {
    const row = this.rows[this.currRow];
    row.clearToEndOfRow();
  }
 
  /**
   * Insert a character (without styling) in the current row.
   */
  insertChar (char: number) {
    const row = this.rows[this.currRow];
    row.insertChar(char);
  }
 
  setPen (styles: Partial<PenStyles>) {
    const row = this.rows[this.currRow];
    row.setPenStyles(styles);
  }
 
  moveCursor (relPos: number) {
    const row = this.rows[this.currRow];
    row.moveCursor(relPos);
  }
 
  setCursor (absPos: number) {
    logger.log('INFO', 'setCursor: ' + absPos);
    const row = this.rows[this.currRow];
    row.setCursor(absPos);
  }
 
  setPAC (pacData: PACData) {
    logger.log('INFO', 'pacData = ' + JSON.stringify(pacData));
    let newRow = pacData.row - 1;
    if (this.nrRollUpRows && newRow < this.nrRollUpRows - 1) {
      newRow = this.nrRollUpRows - 1;
    }
 
    // Make sure this only affects Roll-up Captions by checking this.nrRollUpRows
    if (this.nrRollUpRows && this.currRow !== newRow) {
      // clear all rows first
      for (let i = 0; i < NR_ROWS; i++) {
        this.rows[i].clear();
      }
 
      // Copy this.nrRollUpRows rows from lastOutputScreen and place it in the newRow location
      // topRowIndex - the start of rows to copy (inclusive index)
      const topRowIndex = this.currRow + 1 - (this.nrRollUpRows);
      // We only copy if the last position was already shown.
      // We use the cueStartTime value to check this.
      const lastOutputScreen = this.lastOutputScreen as any;
      if (lastOutputScreen) {
        const prevLineTime = lastOutputScreen.rows[topRowIndex].cueStartTime;
        if (prevLineTime && logger.time && prevLineTime < logger.time) {
          for (let i = 0; i < this.nrRollUpRows; i++) {
            this.rows[newRow - this.nrRollUpRows + i + 1].copy(lastOutputScreen.rows[topRowIndex + i]);
          }
        }
      }
    }
 
    this.currRow = newRow;
    const row = this.rows[this.currRow];
    if (pacData.indent !== null) {
      const indent = pacData.indent;
      const prevPos = Math.max(indent - 1, 0);
      row.setCursor(pacData.indent);
      pacData.color = row.chars[prevPos].penState.foreground;
    }
    const styles: PenStyles = { foreground: pacData.color, underline: pacData.underline, italics: pacData.italics, background: 'black', flash: false };
    this.setPen(styles);
  }
 
  /**
   * Set background/extra foreground, but first do back_space, and then insert space (backwards compatibility).
   */
  setBkgData (bkgData: Partial<PenStyles>) {
    logger.log('INFO', 'bkgData = ' + JSON.stringify(bkgData));
    this.backSpace();
    this.setPen(bkgData);
    this.insertChar(0x20); // Space
  }
 
  setRollUpRows (nrRows: number | null) {
    this.nrRollUpRows = nrRows;
  }
 
  rollUp () {
    if (this.nrRollUpRows === null) {
      logger.log('DEBUG', 'roll_up but nrRollUpRows not set yet');
      return; // Not properly setup
    }
    logger.log('TEXT', this.getDisplayText());
    const topRowIndex = this.currRow + 1 - this.nrRollUpRows;
    const topRow = this.rows.splice(topRowIndex, 1)[0];
    topRow.clear();
    this.rows.splice(this.currRow, 0, topRow);
    logger.log('INFO', 'Rolling up');
    // logger.log('TEXT', this.get_display_text())
  }
 
  /**
   * Get all non-empty rows with as unicode text.
   */
  getDisplayText (asOneRow?: boolean) {
    asOneRow = asOneRow || false;
    const displayText: string[] = [];
    let text = '';
    let rowNr = -1;
    for (let i = 0; i < NR_ROWS; i++) {
      const rowText = this.rows[i].getTextString();
      if (rowText) {
        rowNr = i + 1;
        if (asOneRow) {
          displayText.push('Row ' + rowNr + ': \'' + rowText + '\'');
        } else {
          displayText.push(rowText.trim());
        }
      }
    }
    if (displayText.length > 0) {
      if (asOneRow) {
        text = '[' + displayText.join(' | ') + ']';
      } else {
        text = displayText.join('\n');
      }
    }
    return text;
  }
 
  getTextAndFormat () {
    return this.rows;
  }
}
 
// var modes = ['MODE_ROLL-UP', 'MODE_POP-ON', 'MODE_PAINT-ON', 'MODE_TEXT'];
 
type CaptionModes = 'MODE_ROLL-UP' | 'MODE_POP-ON' | 'MODE_PAINT-ON' | 'MODE_TEXT' | null;
 
class Cea608Channel {
  chNr: number;
  outputFilter: OutputFilter;
  mode: CaptionModes;
  verbose: number;
  displayedMemory: CaptionScreen;
  nonDisplayedMemory: CaptionScreen;
  lastOutputScreen: CaptionScreen;
  currRollUpRow: Row;
  writeScreen: CaptionScreen;
  cueStartTime: number | null;
  lastCueEndTime: null;
  constructor (channelNumber: number, outputFilter: OutputFilter) {
    this.chNr = channelNumber;
    this.outputFilter = outputFilter;
    this.mode = null;
    this.verbose = 0;
    this.displayedMemory = new CaptionScreen();
    this.nonDisplayedMemory = new CaptionScreen();
    this.lastOutputScreen = new CaptionScreen();
    this.currRollUpRow = this.displayedMemory.rows[NR_ROWS - 1];
    this.writeScreen = this.displayedMemory;
    this.mode = null;
    this.cueStartTime = null; // Keeps track of where a cue started.
  }
 
  reset () {
    this.mode = null;
    this.displayedMemory.reset();
    this.nonDisplayedMemory.reset();
    this.lastOutputScreen.reset();
    this.currRollUpRow = this.displayedMemory.rows[NR_ROWS - 1];
    this.writeScreen = this.displayedMemory;
    this.mode = null;
    this.cueStartTime = null;
  }
 
  getHandler (): OutputFilter {
    return this.outputFilter;
  }
 
  setHandler (newHandler: OutputFilter) {
    this.outputFilter = newHandler;
  }
 
  setPAC (pacData: PACData) {
    this.writeScreen.setPAC(pacData);
  }
 
  setBkgData (bkgData: Partial<PenStyles>) {
    this.writeScreen.setBkgData(bkgData);
  }
 
  setMode (newMode: CaptionModes) {
    if (newMode === this.mode) {
      return;
    }
 
    this.mode = newMode;
    logger.log('INFO', 'MODE=' + newMode);
    if (this.mode === 'MODE_POP-ON') {
      this.writeScreen = this.nonDisplayedMemory;
    } else {
      this.writeScreen = this.displayedMemory;
      this.writeScreen.reset();
    }
    if (this.mode !== 'MODE_ROLL-UP') {
      this.displayedMemory.nrRollUpRows = null;
      this.nonDisplayedMemory.nrRollUpRows = null;
    }
    this.mode = newMode;
  }
 
  insertChars (chars: number[]) {
    for (let i = 0; i < chars.length; i++) {
      this.writeScreen.insertChar(chars[i]);
    }
 
    const screen = this.writeScreen === this.displayedMemory ? 'DISP' : 'NON_DISP';
    logger.log('INFO', screen + ': ' + this.writeScreen.getDisplayText(true));
    if (this.mode === 'MODE_PAINT-ON' || this.mode === 'MODE_ROLL-UP') {
      logger.log('TEXT', 'DISPLAYED: ' + this.displayedMemory.getDisplayText(true));
      this.outputDataUpdate();
    }
  }
 
  ccRCL () { // Resume Caption Loading (switch mode to Pop On)
    logger.log('INFO', 'RCL - Resume Caption Loading');
    this.setMode('MODE_POP-ON');
  }
 
  ccBS () { // BackSpace
    logger.log('INFO', 'BS - BackSpace');
    if (this.mode === 'MODE_TEXT') {
      return;
    }
 
    this.writeScreen.backSpace();
    if (this.writeScreen === this.displayedMemory) {
      this.outputDataUpdate();
    }
  }
 
  ccAOF () { // Reserved (formerly Alarm Off)
 
  }
 
  ccAON () { // Reserved (formerly Alarm On)
 
  }
 
  ccDER () { // Delete to End of Row
    logger.log('INFO', 'DER- Delete to End of Row');
    this.writeScreen.clearToEndOfRow();
    this.outputDataUpdate();
  }
 
  ccRU (nrRows: number | null) { // Roll-Up Captions-2,3,or 4 Rows
    logger.log('INFO', 'RU(' + nrRows + ') - Roll Up');
    this.writeScreen = this.displayedMemory;
    this.setMode('MODE_ROLL-UP');
    this.writeScreen.setRollUpRows(nrRows);
  }
 
  ccFON () { // Flash On
    logger.log('INFO', 'FON - Flash On');
    this.writeScreen.setPen({ flash: true });
  }
 
  ccRDC () { // Resume Direct Captioning (switch mode to PaintOn)
    logger.log('INFO', 'RDC - Resume Direct Captioning');
    this.setMode('MODE_PAINT-ON');
  }
 
  ccTR () { // Text Restart in text mode (not supported, however)
    logger.log('INFO', 'TR');
    this.setMode('MODE_TEXT');
  }
 
  ccRTD () { // Resume Text Display in Text mode (not supported, however)
    logger.log('INFO', 'RTD');
    this.setMode('MODE_TEXT');
  }
 
  ccEDM () { // Erase Displayed Memory
    logger.log('INFO', 'EDM - Erase Displayed Memory');
    this.displayedMemory.reset();
    this.outputDataUpdate(true);
  }
 
  ccCR () { // Carriage Return
    logger.log('INFO', 'CR - Carriage Return');
    this.writeScreen.rollUp();
    this.outputDataUpdate(true);
  }
 
  ccENM () { // Erase Non-Displayed Memory
    logger.log('INFO', 'ENM - Erase Non-displayed Memory');
    this.nonDisplayedMemory.reset();
  }
 
  ccEOC () { // End of Caption (Flip Memories)
    logger.log('INFO', 'EOC - End Of Caption');
    if (this.mode === 'MODE_POP-ON') {
      const tmp = this.displayedMemory;
      this.displayedMemory = this.nonDisplayedMemory;
      this.nonDisplayedMemory = tmp;
      this.writeScreen = this.nonDisplayedMemory;
      logger.log('TEXT', 'DISP: ' + this.displayedMemory.getDisplayText());
    }
    this.outputDataUpdate(true);
  }
 
  ccTO (nrCols: number) { // Tab Offset 1,2, or 3 columns
    logger.log('INFO', 'TO(' + nrCols + ') - Tab Offset');
    this.writeScreen.moveCursor(nrCols);
  }
 
  ccMIDROW (secondByte: number) { // Parse MIDROW command
    const styles: Partial<PenStyles> = { flash: false };
    styles.underline = secondByte % 2 === 1;
    styles.italics = secondByte >= 0x2e;
    if (!styles.italics) {
      const colors = ['white', 'green', 'blue', 'cyan', 'red', 'yellow', 'magenta'];
      styles.foreground = colors[Math.floor(secondByte / 2) - 0x10];
    } else {
      styles.foreground = 'white';
    }
    logger.log('INFO', 'MIDROW: ' + JSON.stringify(styles));
    this.writeScreen.setPen(styles);
  }
 
  outputDataUpdate (dispatch = false) {
    const t = logger.time;
    if (t === null) {
      return;
    }
 
    if (this.outputFilter) {
      if (this.cueStartTime === null && !this.displayedMemory.isEmpty()) { // Start of a new cue
        this.cueStartTime = t;
      } else {
        if (!this.displayedMemory.equals(this.lastOutputScreen)) {
          this.outputFilter.newCue(this.cueStartTime!, t, this.lastOutputScreen);
          if (dispatch === true && this.outputFilter.dispatchCue) {
            this.outputFilter.dispatchCue();
          }
 
          this.cueStartTime = this.displayedMemory.isEmpty() ? null : t;
        }
      }
      this.lastOutputScreen.copy(this.displayedMemory);
    }
  }
 
  cueSplitAtTime (t: number) {
    if (this.outputFilter) {
      if (!this.displayedMemory.isEmpty()) {
        if (this.outputFilter.newCue) {
          this.outputFilter.newCue(this.cueStartTime!, t, this.displayedMemory);
        }
 
        this.cueStartTime = t;
      }
    }
  }
}
 
interface PACData {
  row: number;
  indent: number | null;
  color: string | null;
  underline: boolean;
  italics: boolean;
}
 
class Cea608Parser {
  outputs: OutputFilter[];
  channels: Array<Cea608Channel | null>;
  currChNr: 0 | 1 | 2 | 3 | 4 = 0; // Will be 1, 2, 3 or 4 when parsing captions
  cmdHistory: CmdHistory;
  constructor (out1: OutputFilter, out2: OutputFilter, out3: OutputFilter, out4: OutputFilter) {
    this.outputs = [out1, out2];
    this.channels = [
      null,
      new Cea608Channel(1, out1),
      new Cea608Channel(2, out2),
      new Cea608Channel(3, out3),
      new Cea608Channel(4, out4)
    ];
    this.cmdHistory = createCmdHistory();
  }
 
  getHandler (channel: number) {
    return (this.channels[channel] as Cea608Channel).getHandler();
  }
 
  setHandler (channel: number, newHandler: OutputFilter) {
    (this.channels[channel] as Cea608Channel).setHandler(newHandler);
  }
 
  /**
   * Add data for time t in forms of list of bytes (unsigned ints). The bytes are treated as pairs.
   */
  addData (t: number | null, byteList: number[], field: number) {
    let cmdFound: boolean;
    let a: number;
    let b: number;
    let charsFound: number[] | boolean | null = false;
 
    logger.setTime(t);
 
    for (let i = 0; i < byteList.length; i += 2) {
      a = byteList[i] & 0x7f;
      b = byteList[i + 1] & 0x7f;
      if (a === 0 && b === 0) {
        continue;
      } else {
        logger.log('DATA', '[' + numArrayToHexArray([byteList[i], byteList[i + 1]]) + '] -> (' + numArrayToHexArray([a, b]) + ')');
      }
 
      cmdFound = this.parseCmd(a, b, field);
 
      if (!cmdFound) {
        cmdFound = this.parseMidrow(a, b, field);
      }
 
      if (!cmdFound) {
        cmdFound = this.parsePAC(a, b, field);
      }
 
      if (!cmdFound) {
        cmdFound = this.parseBackgroundAttributes(a, b, field);
      }
 
      if (!cmdFound) {
        charsFound = this.parseChars(a, b, field);
        if (charsFound) {
          const currChNr = this.currChNr;
          if (currChNr && currChNr > 0) {
            if (field === 3 && currChNr > 2 || field === 1 && currChNr < 3) {
              const channel = this.channels[currChNr] as Cea608Channel;
              channel.insertChars(charsFound);
            } else {
              logger.log('WARNING', 'The last seen channel number does not fall within the current field. ' +
                'Deferring character insertion until the field and channel match.');
            }
          } else {
            logger.log('WARNING', 'No channel found yet. TEXT-MODE?');
          }
        }
      }
      if (!cmdFound && !charsFound) {
        logger.log('WARNING', 'Couldn\'t parse cleaned data ' + numArrayToHexArray([a, b]) +
          ' orig: ' + numArrayToHexArray([byteList[i], byteList[i + 1]]));
      }
    }
  }
 
  /**
   * Parse Command.
   * @returns {Boolean} Tells if a command was found
   */
  parseCmd (a: number, b: number, field: number) {
    const cmdHistory = this.cmdHistory;
    const chNr = getChannelNumber(a);
    const dataChannel = getDataChannel(b, field);
    const cond1 = chNr && (b >= 0x20 && b <= 0x2F);
    const cond2 = dataChannel && (b >= 0x21 && b <= 0x23);
 
    if (!(cond1 || cond2)) {
      return false;
    }
 
    if (hasCmdRepeated(a, b, cmdHistory[field])) {
      setLastCmd(null, null, cmdHistory[field]);
      logger.log('DEBUG', 'Repeated command (' + numArrayToHexArray([a, b]) + ') is dropped');
      return true;
    }
 
    let channel;
    if (chNr) {
      channel = this.channels[chNr] as Cea608Channel;
      if (b === 0x20) {
        channel.ccRCL();
      } else if (b === 0x21) {
        channel.ccBS();
      } else if (b === 0x22) {
        channel.ccAOF();
      } else if (b === 0x23) {
        channel.ccAON();
      } else if (b === 0x24) {
        channel.ccDER();
      } else if (b === 0x25) {
        channel.ccRU(2);
      } else if (b === 0x26) {
        channel.ccRU(3);
      } else if (b === 0x27) {
        channel.ccRU(4);
      } else if (b === 0x28) {
        channel.ccFON();
      } else if (b === 0x29) {
        channel.ccRDC();
      } else if (b === 0x2A) {
        channel.ccTR();
      } else if (b === 0x2B) {
        channel.ccRTD();
      } else if (b === 0x2C) {
        channel.ccEDM();
      } else if (b === 0x2D) {
        channel.ccCR();
      } else if (b === 0x2E) {
        channel.ccENM();
      } else if (b === 0x2F) {
        channel.ccEOC();
      }
    } else { // a == 0x17 || a == 0x1F
      channel = this.channels[dataChannel!] as Cea608Channel;
      channel.ccTO(b - 0x20);
    }
    setLastCmd(a, b, cmdHistory[field]);
    this.currChNr = chNr;
    return true;
  }
 
  /**
   * Parse midrow styling command
   * @returns {Boolean}
   */
  parseMidrow (a: number, b: number, field: number) {
    let chNr: number = 0;
 
    if (((a === 0x11) || (a === 0x19)) && b >= 0x20 && b <= 0x2f) {
      if (a === 0x11) {
        chNr = field;
      } else {
        chNr = field + 1;
      }
 
      if (chNr !== this.currChNr) {
        logger.log('ERROR', 'Mismatch channel in midrow parsing');
        return false;
      }
      const channel = this.channels[chNr];
      if (!channel) {
        return false;
      }
      channel.ccMIDROW(b);
      logger.log('DEBUG', 'MIDROW (' + numArrayToHexArray([a, b]) + ')');
      return true;
    }
    return false;
  }
 
  /**
   * Parse Preable Access Codes (Table 53).
   * @returns {Boolean} Tells if PAC found
   */
  parsePAC (a: number, b: number, field: number): boolean {
    let chNr: number = 0;
    let row: number;
    const cmdHistory = this.cmdHistory;
 
    const case1 = ((a >= 0x11 && a <= 0x17) || (a >= 0x19 && a <= 0x1F)) && (b >= 0x40 && b <= 0x7F);
    const case2 = (a === 0x10 || a === 0x18) && (b >= 0x40 && b <= 0x5F);
    if (!(case1 || case2)) {
      return false;
    }
 
    if (hasCmdRepeated(a, b, cmdHistory[field])) {
      setLastCmd(null, null, cmdHistory[field]);
      return true; // Repeated commands are dropped (once)
    }
 
    let dataChannel;
    if (a <= 0x17) {
      dataChannel = 1;
      chNr = field;
    } else {
      dataChannel = 2;
      chNr = field + 1;
    }
 
    if (b >= 0x40 && b <= 0x5F) {
      row = (dataChannel === 1) ? rowsLowCh1[a] : rowsLowCh2[a];
    } else { // 0x60 <= b <= 0x7F
      row = (dataChannel === 1) ? rowsHighCh1[a] : rowsHighCh2[a];
    }
    const channel = this.channels[chNr];
    if (!channel) {
      return false;
    }
    channel.setPAC(this.interpretPAC(row, b));
    setLastCmd(a, b, cmdHistory[field]);
    this.currChNr = chNr as 0 | 1 | 2 | 3 | 4;
    return true;
  }
 
  /**
   * Interpret the second byte of the pac, and return the information.
   * @returns {Object} pacData with style parameters.
   */
  interpretPAC (row: number, byte: number): PACData {
    let pacIndex = byte;
    const pacData: PACData = { color: null, italics: false, indent: null, underline: false, row: row };
 
    if (byte > 0x5F) {
      pacIndex = byte - 0x60;
    } else {
      pacIndex = byte - 0x40;
    }
 
    pacData.underline = (pacIndex & 1) === 1;
    if (pacIndex <= 0xd) {
      pacData.color = ['white', 'green', 'blue', 'cyan', 'red', 'yellow', 'magenta', 'white'][Math.floor(pacIndex / 2)];
    } else if (pacIndex <= 0xf) {
      pacData.italics = true;
      pacData.color = 'white';
    } else {
      pacData.indent = (Math.floor((pacIndex - 0x10) / 2)) * 4;
    }
    return pacData; // Note that row has zero offset. The spec uses 1.
  }
 
  /**
   * Parse characters.
   * @returns An array with 1 to 2 codes corresponding to chars, if found. null otherwise.
   */
  parseChars (a: number, b: number, field: number): number[] | null {
    let channelNr: number | null = null;
    let charCodes: number[] | null = null;
    let charCode1: number | null = null;
 
    if (a >= 0x19) {
      channelNr = 2;
      charCode1 = a - 8;
    } else {
      channelNr = 1;
      charCode1 = a;
    }
    if (charCode1 >= 0x11 && charCode1 <= 0x13) {
      // Special character
      let oneCode = b;
      if (charCode1 === 0x11) {
        oneCode = b + 0x50;
      } else if (charCode1 === 0x12) {
        oneCode = b + 0x70;
      } else {
        oneCode = b + 0x90;
      }
 
      logger.log('INFO', 'Special char \'' + getCharForByte(oneCode) + '\' in channel ' + channelNr);
      charCodes = [oneCode];
    } else if (a >= 0x20 && a <= 0x7f) {
      charCodes = (b === 0) ? [a] : [a, b];
    }
    if (charCodes) {
      const hexCodes = numArrayToHexArray(charCodes);
      logger.log('DEBUG', 'Char codes =  ' + hexCodes.join(','));
      setLastCmd(a, b, this.cmdHistory[field]);
    }
    return charCodes;
  }
 
  /**
   * Parse extended background attributes as well as new foreground color black.
   * @returns {Boolean} Tells if background attributes are found
   */
  parseBackgroundAttributes (a: number, b: number, field: number): boolean {
    const case1 = (a === 0x10 || a === 0x18) && (b >= 0x20 && b <= 0x2f);
    const case2 = (a === 0x17 || a === 0x1f) && (b >= 0x2d && b <= 0x2f);
    if (!(case1 || case2)) {
      return false;
    }
    let index: number;
    const bkgData: Partial<PenStyles> = {};
    if (a === 0x10 || a === 0x18) {
      index = Math.floor((b - 0x20) / 2);
      bkgData.background = backgroundColors[index];
      if (b % 2 === 1) {
        bkgData.background = bkgData.background + '_semi';
      }
    } else if (b === 0x2d) {
      bkgData.background = 'transparent';
    } else {
      bkgData.foreground = 'black';
      if (b === 0x2f) {
        bkgData.underline = true;
      }
    }
    const chNr: number = (a < 0x18) ? field : field + 1;
    const channel: Cea608Channel = this.channels[chNr] as Cea608Channel;
    channel.setBkgData(bkgData);
    setLastCmd(a, b, this.cmdHistory[field]);
    return true;
  }
 
  /**
   * Reset state of parser and its channels.
   */
  reset () {
    for (let i = 0; i < Object.keys(this.channels).length; i++) {
      const channel = this.channels[i];
      if (channel) {
        channel.reset();
      }
    }
    this.cmdHistory = createCmdHistory();
  }
 
  /**
   * Trigger the generation of a cue, and the start of a new one if displayScreens are not empty.
   */
  cueSplitAtTime (t: number) {
    for (let i = 0; i < this.channels.length; i++) {
      const channel = this.channels[i];
      if (channel) {
        channel.cueSplitAtTime(t);
      }
    }
  }
}
 
function getChannelNumber (ccData0: number): 0 | 1 | 2 | 3 | 4 {
  if (ccData0 === 0x14) {
    return 1;
  } else if (ccData0 === 0x1C) {
    return 2;
  } else if (ccData0 === 0x15) {
    return 3;
  } else if (ccData0 === 0x1D) {
    return 4;
  }
  return 0;
}
 
function getDataChannel (ccData1: number, field: number): number | null {
  let dataChannel: number | null = null;
  if (ccData1 === 0x17) {
    dataChannel = field;
  } else if (ccData1 === 0x1F) {
    dataChannel = field + 1;
  }
 
  return dataChannel;
}
 
function setLastCmd (a, b, cmdHistory) {
  if (!cmdHistory) {
    return;
  }
 
  cmdHistory.a = a;
  cmdHistory.b = b;
}
 
function hasCmdRepeated (a, b, cmdHistory) {
  if (!cmdHistory) {
    return;
  }
 
  return cmdHistory.a === a && cmdHistory.b === b;
}
 
type CmdHistory = {
  [key: number]: {
    a: number | null,
    b: number | null
  }
};
 
function createCmdHistory (): CmdHistory {
  return {
    1: {
      a: null,
      b: null
    },
    3: {
      a: null,
      b: null
    }
  };
}
 
export default Cea608Parser;