let vertTemplate = [
	'attribute vec2 aVertexPosition;',
	'attribute vec2 aTextureCoord;',

	'uniform float strength;',
	'uniform mat3 projectionMatrix;',

	'varying vec2 vBlurTexCoords[%size%];',

	'void main(void)',
	'{',
	    'gl_Position = vec4((projectionMatrix * vec3((aVertexPosition), 1.0)).xy, 0.0, 1.0);',
		'%blur%',
	'}'
].join('\n');

let generateVertBlurSource = function(kernelSize, x)
{
    let halfLength = Math.ceil(kernelSize/2);

    let vertSource = vertTemplate;

    let blurLoop = '';
    let template;
    let value;

    if(x)
    {
    	template = 'vBlurTexCoords[%index%] = aTextureCoord + vec2(%sampleIndex% * strength, 0.0);';
    }
    else
    {
    	template = 'vBlurTexCoords[%index%] = aTextureCoord + vec2(0.0, %sampleIndex% * strength);';

    }


    for (let i = 0; i < kernelSize; i++)
    {
    	let blur = template.replace('%index%', i);

    	value = i;

    	if(i >= halfLength)
    	{
    		value = kernelSize - i - 1;
    	}

    	blur = blur.replace('%sampleIndex%', (i - (halfLength-1)) + '.0');

    	blurLoop += blur;
    	blurLoop += '\n';
    }

    vertSource = vertSource.replace('%blur%', blurLoop);
    vertSource = vertSource.replace('%size%', kernelSize);

    return vertSource;
};



module.exports = generateVertBlurSource;