import {AbstractGlFilter} from "@engine/renderer/webGl/filters/abstract/abstractGlFilter";
import {ShaderGenerator} from "@engine/renderer/webGl/shaders/generators/shaderGenerator";
import {Game} from "@engine/core/game";
import {GL_TYPE} from "@engine/renderer/webGl/base/shaderProgramUtils";
import {FrameBuffer} from "@engine/renderer/webGl/base/frameBuffer";
import {ISize} from "@engine/geometry/size";

// from https://www.shadertoy.com/view/XtK3W3

export class VideoGlitchFilter extends AbstractGlFilter {

    private readonly iTime:string;
    private readonly iResolution:string;
    private time:number = 0;
    private readonly resolution:[number,number] = [0,0];

    constructor(game:Game){
        super(game);

        const programGen:ShaderGenerator = this.simpleRectDrawer.gen;
        //language=GLSL
        programGen.setFragmentMainFn(MACRO_GL_COMPRESS`
            //
            // Description : Array and textureless GLSL 2D simplex noise function.
            //      Author : Ian McEwan, Ashima Arts.
            //  Maintainer : stegu
            //     Lastmod : 20110822 (ijm)
            //     License : Copyright (C) 2011 Ashima Arts. All rights reserved.
            //               Distributed under the MIT License. See LICENSE file.
            //               https://github.com/ashima/webgl-noise
            //               https://github.com/stegu/webgl-noise
            // 

            vec3 mod289(vec3 x) {
                return x - floor(x * (1.0 / 289.0)) * 289.0;
            }

            vec2 mod289(vec2 x) {
                return x - floor(x * (1.0 / 289.0)) * 289.0;
            }

            vec3 permute(vec3 x) {
                return mod289(((x*34.0)+1.0)*x);
            }

            float snoise(vec2 v)
            {
                const vec4 C = vec4(0.211324865405187,  // (3.0-sqrt(3.0))/6.0
                0.366025403784439,  // 0.5*(sqrt(3.0)-1.0)
                -0.577350269189626,  // -1.0 + 2.0 * C.x
                0.024390243902439); // 1.0 / 41.0
                // First corner
                vec2 i  = floor(v + dot(v, C.yy) );
                vec2 x0 = v -   i + dot(i, C.xx);

                // Other corners
                vec2 i1;
                //i1.x = step( x0.y, x0.x ); // x0.x > x0.y ? 1.0 : 0.0
                //i1.y = 1.0 - i1.x;
                i1 = (x0.x > x0.y) ? vec2(1.0, 0.0) : vec2(0.0, 1.0);
                // x0 = x0 - 0.0 + 0.0 * C.xx ;
                // x1 = x0 - i1 + 1.0 * C.xx ;
                // x2 = x0 - 1.0 + 2.0 * C.xx ;
                vec4 x12 = x0.xyxy + C.xxzz;
                x12.xy -= i1;

                // Permutations
                i = mod289(i); // Avoid truncation effects in permutation
                vec3 p = permute( permute( i.y + vec3(0.0, i1.y, 1.0 ))
                + i.x + vec3(0.0, i1.x, 1.0 ));

                vec3 m = max(0.5 - vec3(dot(x0,x0), dot(x12.xy,x12.xy), dot(x12.zw,x12.zw)), 0.0);
                m = m*m ;
                m = m*m ;

                // Gradients: 41 points uniformly over a line, mapped onto a diamond.
                // The ring size 17*17 = 289 is close to a multiple of 41 (41*7 = 287)

                vec3 x = 2.0 * fract(p * C.www) - 1.0;
                vec3 h = abs(x) - 0.5;
                vec3 ox = floor(x + 0.5);
                vec3 a0 = x - ox;

                // Normalise gradients implicitly by scaling m
                // Approximation of: m *= inversesqrt( a0*a0 + h*h );
                m *= 1.79284291400159 - 0.85373472095314 * ( a0*a0 + h*h );

                // Compute final noise value at P
                vec3 g;
                g.x  = a0.x  * x0.x  + h.x  * x0.y;
                g.yz = a0.yz * x12.xz + h.yz * x12.yw;
                return 130.0 * dot(m, g);
            }

            float rand(vec2 co)
            {
                return fract(sin(dot(co.xy,vec2(12.9898,78.233))) * 43758.5453);
            }


            void main()
            {
                vec2 uv = gl_FragCoord.xy / iResolution.xy;
                float time = iTime * 2.0;

                // Create large, incidental noise waves
                float noise = max(0.0, snoise(vec2(time, uv.y * 0.3)) - 0.3) * (1.0 / 0.7);

                // Offset by smaller, constant noise waves
                noise = noise + (snoise(vec2(time*10.0, uv.y * 2.4)) - 0.5) * 0.15;

                // Apply the noise as x displacement for every line
                float xpos = uv.x - noise * noise * 0.25;
                gl_FragColor = texture2D(texture, vec2(xpos, uv.y));

                // Mix in some random interference for lines
                gl_FragColor.rgb = mix(gl_FragColor.rgb, vec3(rand(vec2(uv.y * time))), noise * 0.3).rgb;

                // Apply a line pattern every 4 pixels
                if (floor(mod(gl_FragCoord.y * 0.25, 2.0)) == 0.0)
                {
                    gl_FragColor.rgb *= 1.0 - (0.15 * noise);
                }

                // Shift green/blue channels (using the red channel)
                gl_FragColor.g = mix(gl_FragColor.r, texture2D(texture, vec2(xpos + noise * 0.05, uv.y)).g, 0.25);
                gl_FragColor.b = mix(gl_FragColor.r, texture2D(texture, vec2(xpos - noise * 0.05, uv.y)).b, 0.25);
            }
            `
        );
        this.iTime = programGen.addScalarFragmentUniform(GL_TYPE.FLOAT,'iTime');
        this.iResolution = programGen.addScalarFragmentUniform(GL_TYPE.FLOAT_VEC2,'iResolution');
        this.simpleRectDrawer.initProgram();
    }


    public doFilter(destFrameBuffer:FrameBuffer):void{
        this.setUniform(this.iTime,this.time+=0.01);
        const size:ISize = this.simpleRectDrawer.getAttachedTextureAt(0).size;
        this.resolution[0] = size.width;
        this.resolution[1] = size.height;
        this.setUniform(this.iResolution,this.resolution);
        super.doFilter(destFrameBuffer);
    }

}
