var _ = require('lodash');
module.exports = exports = function(pixels, constantFactor, kernelValues) {
    let kernel = kernelGenerator(constantFactor, kernelValues), oldpix = _.cloneDeep(pixels);
    kernel = flipKernel(kernel);

    for (let i = 0; i < pixels.shape[0]; i++) {
        for (let j = 0; j < pixels.shape[1]; j++) {
            let neighboutPos = getNeighbouringPixelPositions([i, j]);
            let acc = [0.0, 0.0, 0.0, 0.0];
            for (let a = 0; a < kernel.length; a++) {
                for (let b = 0; b < kernel.length; b++) {
                    acc[0] += (oldpix.get(neighboutPos[a][b][0], neighboutPos[a][b][1], 0) * kernel[a][b]);
                    acc[1] += (oldpix.get(neighboutPos[a][b][0], neighboutPos[a][b][1], 1) * kernel[a][b]);
                    acc[2] += (oldpix.get(neighboutPos[a][b][0], neighboutPos[a][b][1], 2) * kernel[a][b]);
                    acc[3] += (oldpix.get(neighboutPos[a][b][0], neighboutPos[a][b][1], 3) * kernel[a][b]);
                }
            }
            acc[0] = Math.min(acc[0], 255);
            acc[1] = Math.min(acc[1], 255);
            acc[2] = Math.min(acc[2], 255);
            pixels.set(i, j, 0, acc[0]);
            pixels.set(i, j, 1, acc[1]);
            pixels.set(i, j, 2, acc[2]);
        }
    }
    return pixels;


    function kernelGenerator(constantFactor, kernelValues) {
        kernelValues = kernelValues.split(" ");
        for (i = 0; i < 9; i++) {
            kernelValues[i] = Number(kernelValues[i]) * constantFactor;
        }
        let k = 0;
        let arr = [];
        for (i = 0; i < 3; i++) {
            let columns = [];
            for (j = 0; j < 3; j++) {
                columns.push(kernelValues[k]);
                k += 1;
            }
            arr.push(columns);
        }
        return arr;
    }

    function getNeighbouringPixelPositions(pixelPosition) {
        let x = pixelPosition[0], y = pixelPosition[1], result = [];

        for (let i = -1; i <= 1; i++) {
            let arr = [];
            for (let j = -1; j <= 1; j++)
                arr.push([x + i, y + j]);

            result.push(arr);
        }
        return result;
    }

    function flipKernel(kernel) {
        let result = [];
        for (let i = kernel.length - 1; i >= 0; i--) {
            let arr = [];
            for (let j = kernel[i].length - 1; j >= 0; j--) {
                arr.push(kernel[i][j]);
            }
            result.push(arr);
        }
        return result;
    }
}