matrix.js

// List of pieces
const PIECES_LIST = [
    {
        id: 1,
        size: { col: 6, row: 2 },
        length: 1,
    },
    {
        id: 2,
        size: { col: 2, row: 2 },
        length: 1,
    },
    {
        id: 3,
        size: { col: 1, row: 2 },
        length: 2,
    },
    {
        id: 4,
        size: { col: 8, row: 1 },
        length: 1,
    },
    {
        id: 5,
        size: { col: 2, row: 1 },
        length: 3,
    },
    {
        id: 6,
        size: { col: 1, row: 1 },
        length: 6,
    }
];

// Matrix configuration
const MATRIX_CONFIG = { col: 8, row: 5 };

/////////////////////////////////////////

// Create the matrix
function createMatrix(matrix) {
    const row = matrix.row;
    const col = matrix.col;
    const buff = [];

    for (let i = 0; i < row; i++) {
        buff[i] = [];
        for (let j = 0; j < col; j++) {
            buff[i][j] = 0;
        }
    }
    return buff;
}

// Print matrix to console
function printMatrix(matrix) {
    let buff = '';
    for (let i = 0; i < matrix.length; i++) {
        buff += '\r\n' + matrix[i].join(',');
    }

    console.log(buff);
}


// Sorting pieces from < to >
function sortPieces(pieces) {
    return pieces.sort((a, b) => (b.size.col * b.size.row) - (a.size.col * a.size.row));
}

// Get a random number between min and max
function getRandomBetween(min, max) {
    return Math.floor(Math.random() * (max - min + 1) + min);
}

// Function responsible for finding an empty space within the matrix to place the given piece
function findPlace(piece, matrix) {
    let randomRow;
    let randomCol;
    let error;
    let coordinates = [];

    do {
        error = 0;

        do {
            // If the length of the coordinates is equal to the number of tiles in the matrix
            if (coordinates.length === MATRIX_CONFIG.col * MATRIX_CONFIG.row) {
                return false;
            }

            // Get a random coordinate
            randomRow = getRandomBetween(0, matrix.length - 1);
            randomCol = getRandomBetween(0, matrix[randomRow].length - 1);

        } while (coordinates.includes(`${randomRow},${randomCol}`)
            || (matrix[randomRow] > 0 && matrix[randomRow][randomCol] > 0));

        coordinates.push(`${randomRow},${randomCol}`);

        // Check available positions for the given piece
        for (let i = 0; i < piece.size.row; i++) {
            if (matrix[randomRow + i] === undefined || matrix[randomRow + i] > 0) {
                error++;
                break;
            } else {
                for (let j = 0; j < piece.size.col; j++) {
                    if (matrix[randomRow + i][randomCol + j] === undefined
                        || matrix[randomRow + i][randomCol + j] > 0) {
                        error++;
                        break;
                    }
                }
            }
        }

    } while (error > 0);

    // Place piece to the matrix
    const coordinate = { row: randomRow, col: randomCol };
    placePiece(piece, coordinate, matrix);
    return true;
}

// Place given piece id to the matrix 
function placePiece(piece, coordinate, matrix) {
    for (let i = 0; i < piece.size.row; i++) {
        for (let j = 0; j < piece.size.col; j++) {
            matrix[coordinate.row + i][coordinate.col + j] = piece.id;
        }
    }
}

// Walk through pieces
function placePieces(pieces, matrix) {
    let error = 0;

    for (let i = 0; i < pieces.length; i++) {
        const piece = pieces[i];
        let j = piece.length;
        while (j--) {
            if (!findPlace(piece, matrix)) {
                error++
                break;
            }
        }

        if (error > 0) { break; }
    }

    // if there's error try again
    if (error > 0) {
        return false;
    }

    return true;
}

// Recursive process
function process(pieces) {
    const matrix = createMatrix(MATRIX_CONFIG);

    if (!placePieces(pieces, matrix)) {
        process(pieces);
        return false;
    }

    printMatrix(matrix);
}

// Start the process
function start() {
    const pieces = sortPieces(PIECES_LIST);
    process(pieces)
}


// INIT
start();