var AbstractFilter = require('./AbstractFilter');

/**
 * The NormalMapFilter class uses the pixel values from the specified texture (called the displacement map) to perform a displacement of an object.
 * You can use this filter to apply all manor of crazy warping effects
 * Currently the r property of the texture is used offset the x and the g property of the texture is used to offset the y.
 *
 * @class
 * @extends AbstractFilter
 * @namespace PIXI
 * @param texture {Texture} The texture used for the normal map, must be power of 2 texture at the moment
 */
function NormalMapFilter(texture) {
    AbstractFilter.call(this);

    texture.baseTexture._powerOf2 = true;

    // set the uniforms
    this.uniforms = {
        displacementMap:  { type: 'sampler2D', value: texture },
        scale:            { type: '2f', value: { x: 15, y: 15 } },
        offset:           { type: '2f', value: { x: 0,  y: 0 } },
        mapDimensions:    { type: '2f', value: { x: 1,  y: 1 } },
        dimensions:       { type: '4f', value: [0, 0, 0, 0] },
        // LightDir:         { type: 'f3', value: [0, 1, 0] },
        LightPos:         { type: '3f', value: [0, 1, 0] }
    };

    if (texture.baseTexture.hasLoaded) {
        this.onTextureLoaded();
    }
    else {
        this.boundLoadedFunction = this.onTextureLoaded.bind(this);

        texture.baseTexture.on('loaded', this.boundLoadedFunction);
    }

    this.fragmentSrc = [
        'precision mediump float;',

        'varying vec2 vTextureCoord;',
        'varying float vColor;',

        'uniform sampler2D displacementMap;',
        'uniform sampler2D uSampler;',

        'uniform vec4 dimensions;',

        'const vec2 Resolution = vec2(1.0,1.0);',      //resolution of screen
        'uniform vec3 LightPos;',    //light position, normalized
        'const vec4 LightColor = vec4(1.0, 1.0, 1.0, 1.0);',      //light RGBA -- alpha is intensity
        'const vec4 AmbientColor = vec4(1.0, 1.0, 1.0, 0.5);',    //ambient RGBA -- alpha is intensity
        'const vec3 Falloff = vec3(0.0, 1.0, 0.2);',         //attenuation coefficients

        'uniform vec3 LightDir;',//' = vec3(1.0, 0.0, 1.0);',


        'uniform vec2 mapDimensions;',// = vec2(256.0, 256.0);',


        'void main(void) {',
        '   vec2 mapCords = vTextureCoord.xy;',

        '   vec4 color = texture2D(uSampler, vTextureCoord.st);',
        '   vec3 nColor = texture2D(displacementMap, vTextureCoord.st).rgb;',


        '   mapCords *= vec2(dimensions.x/512.0, dimensions.y/512.0);',

        '   mapCords.y *= -1.0;',
        '   mapCords.y += 1.0;',

        //RGBA of our diffuse color
        '   vec4 DiffuseColor = texture2D(uSampler, vTextureCoord);',

        //RGB of our normal map
        '   vec3 NormalMap = texture2D(displacementMap, mapCords).rgb;',

        //The delta position of light
        //'vec3 LightDir = vec3(LightPos.xy - (gl_FragCoord.xy / Resolution.xy), LightPos.z);',
        '   vec3 LightDir = vec3(LightPos.xy - (mapCords.xy), LightPos.z);',
        //Correct for aspect ratio
        // '   LightDir.x *= Resolution.x / Resolution.y;',

        //Determine distance (used for attenuation) BEFORE we normalize our LightDir
        '   float D = length(LightDir);',

        //normalize our vectors
        '   vec3 N = normalize(NormalMap * 2.0 - 1.0);',
        '   vec3 L = normalize(LightDir);',

        //Pre-multiply light color with intensity
        //Then perform 'N dot L' to determine our diffuse term
        '   vec3 Diffuse = (LightColor.rgb * LightColor.a) * max(dot(N, L), 0.0);',

        //pre-multiply ambient color with intensity
        '   vec3 Ambient = AmbientColor.rgb * AmbientColor.a;',

        //calculate attenuation
        '   float Attenuation = 1.0 / ( Falloff.x + (Falloff.y*D) + (Falloff.z*D*D) );',

        //the calculation which brings it all together
        '   vec3 Intensity = Ambient + Diffuse * Attenuation;',
        '   vec3 FinalColor = DiffuseColor.rgb * Intensity;',
        '   gl_FragColor = vColor * vec4(FinalColor, DiffuseColor.a);',
        // '   gl_FragColor = vec4(1.0, 0.0, 0.0, Attenuation);',//vColor * vec4(FinalColor, DiffuseColor.a);',

        /*// normalise color
        '   vec3 normal = normalize(nColor * 2.0 - 1.0);',

        '   vec3 deltaPos = vec3( (light.xy - gl_FragCoord.xy) / resolution.xy, light.z );',

        '   float lambert = clamp(dot(normal, lightDir), 0.0, 1.0);',

        '   float d = sqrt(dot(deltaPos, deltaPos));',
        '   float att = 1.0 / ( attenuation.x + (attenuation.y*d) + (attenuation.z*d*d) );',

        '   vec3 result = (ambientColor * ambientIntensity) + (lightColor.rgb * lambert) * att;',
        '   result *= color.rgb;',

        '   gl_FragColor = vec4(result, 1.0);',*/
        '}'
    ];
}

NormalMapFilter.prototype = Object.create(AbstractFilter.prototype);
NormalMapFilter.prototype.constructor = NormalMapFilter;
module.exports = NormalMapFilter;

/**
 * Sets the map dimensions uniforms when the texture becomes available.
 *
 */
NormalMapFilter.prototype.onTextureLoaded = function () {
    this.uniforms.mapDimensions.value.x = this.uniforms.displacementMap.value.width;
    this.uniforms.mapDimensions.value.y = this.uniforms.displacementMap.value.height;

    this.uniforms.displacementMap.value.baseTexture.off('loaded', this.boundLoadedFunction);
};

Object.defineProperties(NormalMapFilter.prototype, {
    /**
     * The texture used for the displacement map. Must be power of 2 texture.
     *
     * @member {Texture}
     * @memberof NormalMapFilter#
     */
    map: {
        get: function () {
            return this.uniforms.displacementMap.value;
        },
        set: function (value) {
            this.uniforms.displacementMap.value = value;
        }
    },

    /**
     * The multiplier used to scale the displacement result from the map calculation.
     *
     * @member {Point}
     * @memberof NormalMapFilter#
     */
    scale: {
        get: function () {
            return this.uniforms.scale.value;
        },
        set: function (value) {
            this.uniforms.scale.value = value;
        }
    },

    /**
     * The offset used to move the displacement map.
     *
     * @member {Point}
     * @memberof NormalMapFilter#
     */
    offset: {
        get: function () {
            return this.uniforms.offset.value;
        },
        set: function (value) {
            this.uniforms.offset.value = value;
        }
    }
});