/*
Copyright 2022 Paul Ratcliffe

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

const size = 4;
let lang = "en";
const messages = {
  en: {
    cellValue: "The value of this cell is ",
    cellEmpty: "This cell is empty.",
    cellEmptyShort: "Empty",
    cellCorrect: "This cell is correct",
    cellCorrectShort: "correct",
    cellIncorrect: "This cell is incorrect",
    cellIncorrectShort: "incorrect",
    cellFixedShort: "fixed value",
    boardCorrect: "Congratulations, you completed the Sudoku correctly!",
    boardIncorrect: "Hmmm... Not quite correct! Try again. Check 'HIGHLIGHT' to see where you went wrong.",
    where: "You are currently in ",
    currentRow: "current row",
    currentColumn: "current column",
    currentSquare: "square",
    reading: "Reading",
    help: `
            <div class="welcome-message">
              <h2>How to play</h2>
              <p>Note: this version of the game has the partial vision simulation on by default. You can turn it off using the controls below the board or by using the keyboard shortcuts explained below. Other than this simulation, mouse users can use the game just as any other online sudoku game.
              <p>This is a simpler version of sudoku that uses just the numbers 1 to 4 rather than 1 to 9.
              <p>The game BOARD consists of 4 SQUARES arranged in a 2 by 2 grid. The SQUARES in the top row are designated SQUARE A and SQUARE B. The SQUARES in the bottom row are designated SQUARE C and SQUARE D.
              <p>Each SQUARE contains 4 CELLS arranged in a 2 by 2 grid. The CELLS in the top row of each SQUARE are designated CELL A and CELL B. The CELLS in the bottom row are designated CELL C and CELL D.
              <p>Keyboard users can use TAB and SHIFT+TAB to move through each of the cells one by one in SQUARE, then CELL order. So, as you tab you will travel through all 4 CELLS of SQUARE A, then all 4 CELLS of SQUARE B, etc.
              <p>If you are using a screenreader or can see the simulated screenreader output, you can tell which SQUARE and which CELL you are in at all times, as well as the current value of the cell.
              <p>You can use keyboard shortcuts to move quickly around the board and also to have the screenreader announce the other numbers that are entered in your current SQUARE, ROW or COLUMN. Keyboard shortcuts are only active whilst the keyboard focus is within the game. The keyboard shortcuts are:
              <ul>
                <li>W: Give details of current cell.
                <li>RR: Read current ROW.
                <li>RC: Read current COLUMN.
                <li>RS: Read current SQUARE.
                <li>Cursor keys: Go to adjacent cell in indicated direction. 
                <li>G[SQUARE][CELL]: Go to chosen cell. E.g. GBC will move the keyboard focus to SQUARE B, CELL C.
                <li>CC: Check your answers. This will tell you if the sudoku is completely solved or not.
                <li>CH: Toggle highlighting which cells are correct and which are incorrect.
                <li>CS: Reveal solution.
                <li>CR: Restart game.
                <li>CF: Toggle simulating full loss of vision by hiding the board completely.
                <li>CP: Toggle simulating partial sight by blurring the board. This is on by default.
                <li>CO: Toggle displaying simulated screenreader output below the board.
              </ul>
            </div>
          `
  },
  announcementScreenreaderOnlyDisplayed: false,
  announcementAllUsersDisplayed: false
}
let keyboardNavCapture = 0;
let capturedKeys = "";

document.querySelector('#help').innerHTML = messages[lang].help;

document.querySelectorAll('.square input').forEach( (cell) => {

  cell.addEventListener('focus', (e) => {
    let cellValue = e.target.value;
    let cellMessage = " " + messages[lang].cellValue + " " + cellValue + ".";
    if(cellValue == ""){
      cellMessage = " " + messages[lang].cellEmpty;
    }

    document.querySelector('#sr-simulation-text').innerHTML = e.target.ariaLabel + cellMessage;
  } );
  
  cell.addEventListener('blur', (e) => {
    document.querySelector("#announcement-sr-only").innerText = "";
    if(e.target.classList.contains('readonly')){
     e.target.value = e.target.dataset.correct; 
    } else {
      let currentValue = parseInt(e.target.value);
      if(Number.isNaN(currentValue)) {
        currentValue = 0;
      }
      if(currentValue < 1 || currentValue > size){
        e.target.value = "";
      }
    }
    document.querySelector('#sr-simulation-text').innerHTML = "";
    if(messages.announcementScreenreaderOnlyDisplayed){
      document.querySelector('#announcement-sr-only').innerHTML = "";
      messages.announcementScreenreaderOnlyDisplayed = false;
    }
    if(messages.announcementAllUsersDisplayed){
      document.querySelector('#announcement-all-users').innerHTML = "";
      messages.announcementAllUsersDisplayed = false;
    }
    if(document.querySelector('#highlight').checked){
      let ariaLabelSplit = e.target.ariaLabel.split('.');
      if(e.target.value === e.target.dataset.correct){
        e.target.classList.add("correct");
        e.target.classList.remove("incorrect");
        e.target.ariaLabel = ariaLabelSplit[0] + ". " + messages[lang].cellCorrect;
      } else {
        e.target.classList.add("incorrect");
        e.target.classList.remove("correct");
        e.target.ariaLabel = ariaLabelSplit[0] + ". " + messages[lang].cellIncorrect;
      }
    }
  } );
} );

function checkAnswer(e) {
  let allCorrect = true;
  document.querySelectorAll('.square input').forEach( (cell) => {
    if( cell.value !== cell.dataset.correct){
      allCorrect = false;
    }  
  } );
  if(allCorrect){
    document.querySelector('#announcement-all-users').innerHTML = messages[lang].boardCorrect;
  } else {
    document.querySelector('#announcement-all-users').innerHTML = messages[lang].boardIncorrect;    
  }
  messages.announcementAllUsersDisplayed = true;  
}

document.querySelector('#check').addEventListener('click', checkAnswer );


function showSolution(e){
  if(messages.announcementScreenreaderOnlyDisplayed){
    document.querySelector('#announcement-sr-only').innerHTML = "";
    messages.announcementScreenreaderOnlyDisplayed = false;
  }
  if(messages.announcementAllUsersDisplayed){
    document.querySelector('#announcement-all-users').innerHTML = "";
    messages.announcementAllUsersDisplayed = false;
  }
  document.querySelectorAll('.square input').forEach( (cell) => {
    cell.value = cell.dataset.correct;
  } );  
}

document.querySelector('#show').addEventListener('click', showSolution );


function restartGame(e){
  if(messages.announcementScreenreaderOnlyDisplayed){
    document.querySelector('#announcement-sr-only').innerHTML = "";
    messages.announcementScreenreaderOnlyDisplayed = false;
  }
  if(messages.announcementAllUsersDisplayed){
    document.querySelector('#announcement-all-users').innerHTML = "";
    messages.announcementAllUsersDisplayed = false;
  }
  document.querySelectorAll('.square input:not(.readonly)').forEach( (cell) => {
      cell.value = "";   
  } );  
}

document.querySelector('#restart').addEventListener('click', restartGame );


function highlightCells(e){
  if(messages.announcementScreenreaderOnlyDisplayed){
    document.querySelector('#announcement-sr-only').innerHTML = "";
    messages.announcementScreenreaderOnlyDisplayed = false;
  }
  if(document.querySelector('#highlight').checked){
    document.querySelector('#highlight-help').classList.remove('v-hidden');
  } else {
    document.querySelector('#highlight-help').classList.add('v-hidden');    
  }
  document.querySelectorAll('.square input:not(.readonly)').forEach( (cell) => {
    let ariaLabelSplit = cell.ariaLabel.split('.');
    if(document.querySelector('#highlight').checked){
      if(cell.value === cell.dataset.correct){
        cell.classList.add("correct");
        cell.classList.remove("incorrect");
        cell.ariaLabel = ariaLabelSplit[0] + ". " + messages[lang].cellCorrect;
      } else {
        cell.classList.add("incorrect");
        cell.classList.remove("correct");
        cell.ariaLabel = ariaLabelSplit[0] + ". " + messages[lang].cellIncorrect;
      }
    } else {
      cell.classList.remove("correct","incorrect");
      cell.ariaLabel = ariaLabelSplit[0];
    }  
  } );
}

document.querySelector('#highlight').addEventListener('change', highlightCells );


function blurBoard(e){
  if(document.querySelector('#blur').checked){
    document.querySelector('.board').classList.add('blur');    
  } else {
    document.querySelector('.board').classList.remove('blur');
  }
}

document.querySelector('#blur').addEventListener('change', blurBoard );


function hideBoard(e){
  if(document.querySelector('#hide').checked){
    document.querySelector('.board').classList.add('hide');    
  } else {
    document.querySelector('.board').classList.remove('hide');
  }
}

document.querySelector('#hide').addEventListener('change', hideBoard );


function showScreenreaderSimulation(e){
  if(document.querySelector('#simulate-sr').checked){
    document.querySelector('.sr-simulation').classList.remove('hide');    
  } else {
    document.querySelector('.sr-simulation').classList.add('hide');
  }
}

document.querySelector('#simulate-sr').addEventListener('change', showScreenreaderSimulation );


document.querySelector('.board').addEventListener('keydown', (e) => {
  if (e.defaultPrevented) {
    return; // Do nothing if the event was already processed
  }
 
  if(e.key === "Escape"){
    keyboardNavCapture = 0;
    capturedKeys = "";
  } else if(e.key.length > 5 && e.key.substring(0,5) === "Arrow"){
    keyboardNavCapture = 0;
    capturedKeys = "";
    e.preventDefault();
    let activeCellId = parseInt(document.activeElement.id);
    if(!Number.isNaN(activeCellId)) {
      let targetCellId = 0;
      switch (e.key) {
        case "ArrowUp":
          targetCellId = activeCellId - 10;
          break;
        case "ArrowRight":
          targetCellId = activeCellId + 1;
          break;
        case "ArrowDown":
          targetCellId = activeCellId + 10;
          break;
        case "ArrowLeft":
          targetCellId = activeCellId - 1;
          break;
      }
      if(targetCellId > 10 && targetCellId < ((size * 11) + 1)  ) {
        if(document.getElementById('' + targetCellId)){
          document.getElementById('' + targetCellId).focus();      
          document.getElementById('' + targetCellId).select();      
        }
      }
    }
  } else if(keyboardNavCapture === 0){
    
    if(e.key === "g" || e.key === "G"){ // GO action. Capture the next two key presses to determine where to go
      keyboardNavCapture = 2;
      capturedKeys = "G";
      e.preventDefault();
    } else if(e.key === "r" || e.key === "R"){ // READ action. Capture the next key press to determine what to read
      keyboardNavCapture = 1;
      capturedKeys = "R";
      e.preventDefault();
    } else if(e.key === "c" || e.key === "C"){ // CONTROL action. Capture the next key press to determine which control action
      keyboardNavCapture = 1;
      capturedKeys = "C";
      e.preventDefault();
    } else if(e.key === "w" || e.key === "W"){ // WHERE action. Carry out immediately
      let announcementScreenreaderOnly = messages[lang].where + document.activeElement.ariaLabel;
      cellValue = document.activeElement.value;
      if(cellValue === ""){
        cellValue = messages[lang].cellEmptyShort;
      } else if(document.activeElement.classList.contains('readonly')){
        cellValue += " (" + messages[lang].cellFixedShort + ")";
      } else if(document.querySelector('#highlight').checked){
        if(cellValue === document.activeElement.dataset.correct){
          cellValue += " (" + messages[lang].cellCorrectShort + ")";
        } else {
          cellValue += " (" + messages[lang].cellIncorrectShort + ")";
        }                  
      }
      document.querySelector("#announcement-sr-only").innerText = announcementScreenreaderOnly + " " + messages[lang].cellValue + cellValue + ".";
      e.preventDefault();
    } else if(e.key === "h" || e.key === "H"){ // HELP action. Carry out immediately
      document.querySelector("#announcement-sr-only").innerHTML = messages[lang].help;
      e.preventDefault();
    }
    
  } else {
    capturedKeys += e.key.toUpperCase();
    keyboardNavCapture = keyboardNavCapture - 1;
    e.preventDefault();
    if(keyboardNavCapture == 0){
      let actionType = capturedKeys[0];
      let actionDetails = capturedKeys.substring(1); 
      capturedKeys = "";
      if(actionType === "R"){ // READ action
        let activeCellId = parseInt(document.activeElement.id);
        if( (actionDetails === "R" || actionDetails === "C" || actionDetails === "S") && !Number.isNaN(activeCellId) ){
          let row = parseInt(document.activeElement.id[0]) * 10;
          let column = parseInt(document.activeElement.id[1]);
          let cellValue = "";
          let announcementScreenreaderOnly = messages[lang].reading + " ";
          switch (actionDetails){
            case "R":
              announcementScreenreaderOnly += messages[lang].currentRow + ":";
              for (let col = 1; col < (size + 1); col++) {
                cellValue = document.getElementById("" + (row + col)).value;
                if(cellValue === ""){
                  cellValue = messages[lang].cellEmptyShort;
                } else if(document.getElementById("" + (row + col)).classList.contains('readonly')){
                  cellValue += " (" + messages[lang].cellFixedShort + ")";
                } else if(document.querySelector('#highlight').checked){
                  if(cellValue === document.getElementById("" + (row + col)).dataset.correct){
                    cellValue += " (" + messages[lang].cellCorrectShort + ")";  
                  } else {
                    cellValue += " (" + messages[lang].cellIncorrectShort + ")";
                  }                  
                }
                announcementScreenreaderOnly += " " + cellValue;
                if(col < size){
                  announcementScreenreaderOnly += ",";
                }
              }
              break;
            case "C":
              announcementScreenreaderOnly += messages[lang].currentColumn + ":";
              for (let r = 10; r < ((size + 1) * 10); r = r+10) {
                cellValue = document.getElementById("" + (r + column)).value;
                if(cellValue === ""){
                  cellValue = messages[lang].cellEmptyShort;
                } else if(document.getElementById("" + (r + column)).classList.contains('readonly')){
                  cellValue += " (" + messages[lang].cellFixedShort + ")";
                } else if(document.querySelector('#highlight').checked){
                  if(cellValue === document.getElementById("" + (r + column)).dataset.correct){
                    cellValue += " (" + messages[lang].cellCorrectShort + ")";
                  } else {
                    cellValue += " (" + messages[lang].cellIncorrectShort + ")";
                  }                  
                }
                announcementScreenreaderOnly += " " + cellValue;
                if(r < size * 10){
                  announcementScreenreaderOnly += ",";
                }
              }
              break;
            case "S":
              let square = document.activeElement.parentNode;
              announcementScreenreaderOnly += messages[lang].currentSquare + " " + square.dataset.id + ":";
              for (let cell = 65; cell < (size + 65); cell++) {
                cellValue = square.querySelector('input[data-id="' + String.fromCharCode(cell) + '"]').value;
                if(cellValue === ""){
                  cellValue = messages[lang].cellEmptyShort;
                } else if(square.querySelector('input[data-id="' + String.fromCharCode(cell) + '"]').classList.contains('readonly')){
                  cellValue += " (" + messages[lang].cellFixedShort + ")";
                } else if(document.querySelector('#highlight').checked){
                  if(cellValue === square.querySelector('input[data-id="' + String.fromCharCode(cell) + '"]').dataset.correct){
                    cellValue += " (" + messages[lang].cellCorrectShort + ")";
                  } else {
                    cellValue += " (" + messages[lang].cellIncorrectShort + ")";
                  }                  
                }
                announcementScreenreaderOnly += " " + cellValue;
                if(cell < (size + 64) ){
                  announcementScreenreaderOnly += ",";
                }
              }

              break;
          }
          document.querySelector("#announcement-sr-only").innerText = announcementScreenreaderOnly;
        }
      }
      if(actionType === "G"){ // GO action
        if( (actionDetails.charCodeAt(0) - 65) < size && (actionDetails.charCodeAt(1) - 65) < size ){
          let targetCell = document.querySelector('.square[data-id="' + actionDetails[0] + '"] input[data-id="' + actionDetails[1] + '"]');
          if(targetCell){
            targetCell.focus();
            targetCell.select();
          }
        }
      }
      if(actionType === "C"){
        switch (actionDetails){
          case "F":
            if(document.querySelector('#hide').checked){
              document.querySelector('#hide').checked = false;
            } else {
              document.querySelector('#hide').checked = true;
            }
            hideBoard(null);
            break;
          case "P":
            if(document.querySelector('#blur').checked){
              document.querySelector('#blur').checked = false;
            } else {
              document.querySelector('#blur').checked = true;
            }
            blurBoard(null);
            break;
          case "O":
            if(document.querySelector('#simulate-sr').checked){
              document.querySelector('#simulate-sr').checked = false;
            } else {
              document.querySelector('#simulate-sr').checked = true;
            }
            showScreenreaderSimulation(null);
            break;
          case "H":
            if(document.querySelector('#highlight').checked){
              document.querySelector('#highlight').checked = false;
            } else {
              document.querySelector('#highlight').checked = true;
            }
            highlightCells(null);
            break;
          case "C":
            checkAnswer(null);
            break;
          case "S":
            showSolution(null);
            break;
          case "R":
            restartGame(null);
            break;
        }

      }

    }
  }

});