var Sudoku = (function() {

    var matrix;

    var createMatrix = function() {
        matrix = new Array(9);
        for (var i=0; i<matrix.length; i++) {
            matrix[i] = new Array(9);
        }
        populateMatrix();
    };

    var populateMatrix = function() {
        var possibles = generatePossibleNumbersArray();
        var found = false;
        for(var i=0; i< matrix.length; i++) {
            for(var j=0; j< matrix[i].length; j++) {
                while(possibles[i][j].length > 0) {
                    var rnd = Math.floor(Math.random() * possibles[i][j].length);
                    var num = possibles[i][j].splice(rnd, 1)[0];
                    if(isValid(i, j, num)) {
                        matrix[i][j] = num;
                        found = true;
                        break;
                    } else {
                        found = false;
                        continue;
                    }
                }
                if(!found) {
                    matrix[i][j] = undefined;
                    possibles[i][j] = [1,2,3,4,5,6,7,8,9];
                    j -= 2;
                }
            }
        }
    }

    var generatePossibleNumbersArray = function() {
        var possibles = new Array(9);
        for(var i=0; i<possibles.length; i++) {
            possibles[i] = new Array(9);
            for(var j=0; j< possibles[i].length; j++) {
                possibles[i][j] = [1,2,3,4,5,6,7,8,9];
            }
        }
        return possibles;
    }

    var getRow = function(index) {
        var row = [];
        for (var i=0; i< 9; i++) {
            row.push(matrix[index][i]);
        }
        return row;
    }

    var getCol = function(index) {
        var col = [];
        for (var i=0; i<9; i++) {
            col.push(matrix[i][index]);
        }
        return col;
    }

    var isValid = function(row, col, val) {
        var valid = true;
        if(inRow(row, val) || inCol(col, val) || inGrid(row, col, val)) {
            valid = false;
        }
        return valid;
    }

    var inGrid = function(row, col, val) {
        var x, y;
        var found = false;

        x = Math.floor(row / 3) * 3;
        y = Math.floor(col / 3) * 3;

        for (var i=x; i < x+3; i++) {
            for (var j=y; j < y+3; j++) {
                if(matrix[i][j] === val) {
                    found = true;
                }
            }
        }
        return found;
    }

    var inRow = function(row, val) {
        var theRow = getRow(row);
        return inArr(theRow, val);
    }

    var inCol = function(col, val) {
        var theCol = getCol(col);
        return inArr(theCol, val);
    }

    var inArr = function(arr, val) {
        var found = false;
        var length = arr.length;
        for (var i=0; i< length; i++) {
            if(arr[i] === val && val !== undefined) {
                found = true;
                break;
                console.log("Matched "+arr[i] + " with "+val);
            }
        }
        return found;
    }

    var createBoard = function() {
        var body = document.getElementsByTagName("body")[0];
        var input;
        for (var i=0; i<9; i++) {
            for (var j=0; j<9; j++) {
                var br = document.createElement('br');
                input = document.createElement('input');
                input.name = 'cell'+i+j;
                input.id = 'cell'+i+j;
                input.style.width = "20px";
                input.style.height = "20px";
                input.style.margin = "1px";
                document.getElementsByTagName('body')[0].appendChild(input);
                if((j+1) % 9 === 0) {
                    document.getElementsByTagName('body')[0].appendChild(br);
                }
            }
        }
        updateBoard();
    }

    var updateBoard = function() {
        for (var i=0; i<9; i++) {
            for (var j=0; j<9; j++) {
                var input = document.getElementById("cell"+i+j);
                input.value = matrix[i][j];
            }
        }
    }

    var randomNum = function() {
        return Math.floor(Math.random() * 9 + 1);
    }

    return {
        createMatrix : createMatrix,
        populateMatrix : populateMatrix,
        createBoard : createBoard,
        updateBoard : updateBoard
    };

})();

Sudoku.createMatrix();
Sudoku.populateMatrix();
Sudoku.createBoard();
Sudoku.populateBoard();