/**
 * @author       Richard Davey <rich@photonstorm.com>
 * @copyright    2020 Photon Storm Ltd.
 * @license      {@link https://opensource.org/licenses/MIT|MIT License}
 */

var AddBlendFS = require('../shaders/AddBlend-frag.js');
var Class = require('../../../utils/Class');
var ColorMatrix = require('../../../display/ColorMatrix');
var ColorMatrixFS = require('../shaders/ColorMatrix-frag.js');
var CopyFS = require('../shaders/Copy-frag.js');
var GetFastValue = require('../../../utils/object/GetFastValue');
var LinearBlendFS = require('../shaders/LinearBlend-frag.js');
var QuadVS = require('../shaders/Quad-vert.js');
var WEBGL_CONST = require('../const');
var WebGLPipeline = require('../WebGLPipeline');

/**
 * @classdesc
 * The Utility Pipeline is a special-use pipeline that belongs to the Pipeline Manager.
 *
 * It provides 4 shaders and handy associated methods:
 *
 * 1) Copy Shader. A fast texture to texture copy shader with optional brightness setting.
 * 2) Additive Blend Mode Shader. Blends two textures using an additive blend mode.
 * 3) Linear Blend Mode Shader. Blends two textures using a linear blend mode.
 * 4) Color Matrix Copy Shader. Draws a texture to a target using a Color Matrix.
 *
 * You typically do not extend or access this pipeline directly, but instead go
 * via the following methods in the Pipeline Manager:
 *
 * `copyFrame`
 * `drawFrame`
 * `blendFrames`
 * `blendFramesAdditive`
 *
 * The default shader attributes for this pipeline are:
 *
 * `inPosition` (vec2, offset 0)
 * `inTexCoord` (vec2, offset 8)
 *
 * This pipeline has a hard-coded batch size of 1 and a hard coded set of vertices.
 *
 * @class UtilityPipeline
 * @extends Phaser.Renderer.WebGL.WebGLPipeline
 * @memberof Phaser.Renderer.WebGL.Pipelines
 * @constructor
 * @since 3.50.0
 *
 * @param {Phaser.Types.Renderer.WebGL.WebGLPipelineConfig} config - The configuration options for this pipeline.
 */
var UtilityPipeline = new Class({

    Extends: WebGLPipeline,

    initialize:

    function UtilityPipeline (config)
    {
        config.renderTarget = GetFastValue(config, 'renderTarget', [
            {
                scale: 1
            },
            {
                scale: 1
            },
            {
                scale: 0.5
            },
            {
                scale: 0.5
            }
        ]);

        config.vertShader = GetFastValue(config, 'vertShader', QuadVS);

        config.shaders = GetFastValue(config, 'shaders', [
            {
                name: 'Copy',
                fragShader: CopyFS,
                uniforms: [
                    'uMainSampler',
                    'uBrightness'
                ]
            },
            {
                name: 'AddBlend',
                fragShader: AddBlendFS,
                uniforms: [
                    'uMainSampler1',
                    'uMainSampler2',
                    'uStrength'
                ]
            },
            {
                name: 'LinearBlend',
                fragShader: LinearBlendFS,
                uniforms: [
                    'uMainSampler1',
                    'uMainSampler2',
                    'uStrength'
                ]
            },
            {
                name: 'ColorMatrix',
                fragShader: ColorMatrixFS,
                uniforms: [
                    'uMainSampler',
                    'uColorMatrix',
                    'uAlpha'
                ]
            }
        ]);

        config.attributes = GetFastValue(config, 'attributes', [
            {
                name: 'inPosition',
                size: 2,
                type: WEBGL_CONST.FLOAT
            },
            {
                name: 'inTexCoord',
                size: 2,
                type: WEBGL_CONST.FLOAT
            }
        ]);

        //  x, y, u, v (x/y in NDC)
        config.vertices = new Float32Array([
            -1, -1, 0, 0,
            -1, 1, 0, 1,
            1, 1, 1, 1,
            -1, -1, 0, 0,
            1, 1, 1, 1,
            1, -1, 1, 0
        ]);

        config.batchSize = 1;

        WebGLPipeline.call(this, config);

        /**
         * A default Color Matrix, used by the Color Matrix Shader when one
         * isn't provided.
         *
         * @name Phaser.Renderer.WebGL.Pipelines.UtilityPipeline#colorMatrix
         * @type {Phaser.Display.ColorMatrix}
         * @since 3.50.0
         */
        this.colorMatrix = new ColorMatrix();

        /**
         * A reference to the Copy Shader belonging to this Utility Pipeline.
         *
         * This property is set during the `boot` method.
         *
         * @name Phaser.Renderer.WebGL.Pipelines.UtilityPipeline#copyShader
         * @type {Phaser.Renderer.WebGL.WebGLShader}
         * @default null
         * @since 3.50.0
         */
        this.copyShader;

        /**
         * A reference to the Additive Blend Shader belonging to this Utility Pipeline.
         *
         * This property is set during the `boot` method.
         *
         * @name Phaser.Renderer.WebGL.Pipelines.UtilityPipeline#addShader
         * @type {Phaser.Renderer.WebGL.WebGLShader}
         * @since 3.50.0
         */
        this.addShader;

        /**
         * A reference to the Linear Blend Shader belonging to this Utility Pipeline.
         *
         * This property is set during the `boot` method.
         *
         * @name Phaser.Renderer.WebGL.Pipelines.UtilityPipeline#linearShader
         * @type {Phaser.Renderer.WebGL.WebGLShader}
         * @since 3.50.0
         */
        this.linearShader;

        /**
         * A reference to the Color Matrix Shader belonging to this Utility Pipeline.
         *
         * This property is set during the `boot` method.
         *
         * @name Phaser.Renderer.WebGL.Pipelines.UtilityPipeline#colorMatrixShader
         * @type {Phaser.Renderer.WebGL.WebGLShader}
         * @since 3.50.0
         */
        this.colorMatrixShader;

        /**
         * A reference to the Full Frame 1 Render Target.
         *
         * This property is set during the `boot` method.
         *
         * This Render Target is the full size of the renderer.
         *
         * You can use this directly in Post FX Pipelines for multi-target effects.
         * However, be aware that these targets are shared between all post fx pipelines.
         *
         * @name Phaser.Renderer.WebGL.Pipelines.UtilityPipeline#fullFrame1
         * @type {Phaser.Renderer.WebGL.RenderTarget}
         * @since 3.50.0
         */
        this.fullFrame1;

        /**
         * A reference to the Full Frame 2 Render Target.
         *
         * This property is set during the `boot` method.
         *
         * This Render Target is the full size of the renderer.
         *
         * You can use this directly in Post FX Pipelines for multi-target effects.
         * However, be aware that these targets are shared between all post fx pipelines.
         *
         * @name Phaser.Renderer.WebGL.Pipelines.UtilityPipeline#fullFrame2
         * @type {Phaser.Renderer.WebGL.RenderTarget}
         * @since 3.50.0
         */
        this.fullFrame2;

        /**
         * A reference to the Half Frame 1 Render Target.
         *
         * This property is set during the `boot` method.
         *
         * This Render Target is half the size of the renderer.
         *
         * You can use this directly in Post FX Pipelines for multi-target effects.
         * However, be aware that these targets are shared between all post fx pipelines.
         *
         * @name Phaser.Renderer.WebGL.Pipelines.UtilityPipeline#halfFrame1
         * @type {Phaser.Renderer.WebGL.RenderTarget}
         * @since 3.50.0
         */
        this.halfFrame1;

        /**
         * A reference to the Half Frame 2 Render Target.
         *
         * This property is set during the `boot` method.
         *
         * This Render Target is half the size of the renderer.
         *
         * You can use this directly in Post FX Pipelines for multi-target effects.
         * However, be aware that these targets are shared between all post fx pipelines.
         *
         * @name Phaser.Renderer.WebGL.Pipelines.UtilityPipeline#halfFrame2
         * @type {Phaser.Renderer.WebGL.RenderTarget}
         * @since 3.50.0
         */
        this.halfFrame2;
    },

    boot: function ()
    {
        WebGLPipeline.prototype.boot.call(this);

        var shaders = this.shaders;
        var targets = this.renderTargets;

        this.copyShader = shaders[0];
        this.addShader = shaders[1];
        this.linearShader = shaders[2];
        this.colorMatrixShader = shaders[3];

        this.fullFrame1 = targets[0];
        this.fullFrame2 = targets[1];
        this.halfFrame1 = targets[2];
        this.halfFrame2 = targets[3];
    },

    /**
     * Copy the `source` Render Target to the `target` Render Target.
     *
     * You can optionally set the brightness factor of the copy.
     *
     * The difference between this method and `drawFrame` is that this method
     * uses a faster copy shader, where only the brightness can be modified.
     * If you need color level manipulation, see `drawFrame` instead.
     *
     * @method Phaser.Renderer.WebGL.Pipelines.UtilityPipeline#copyFrame
     * @since 3.50.0
     *
     * @param {Phaser.Renderer.WebGL.RenderTarget} source - The source Render Target.
     * @param {Phaser.Renderer.WebGL.RenderTarget} [target] - The target Render Target.
     * @param {number} [brightness=1] - The brightness value applied to the frame copy.
     * @param {boolean} [clearAlpha=true] - Clear the alpha channel when running `gl.clear` on the target?
     */
    copyFrame: function (source, target, brightness, clearAlpha)
    {
        if (brightness === undefined) { brightness = 1; }
        if (clearAlpha === undefined) { clearAlpha = true; }

        var gl = this.gl;

        this.set1i('uMainSampler', 0, this.copyShader);
        this.set1f('uBrightness', brightness, this.copyShader);

        gl.activeTexture(gl.TEXTURE0);
        gl.bindTexture(gl.TEXTURE_2D, source.texture);

        if (target)
        {
            gl.viewport(0, 0, target.width, target.height);
            gl.bindFramebuffer(gl.FRAMEBUFFER, target.framebuffer);
            gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, target.texture, 0);
        }
        else
        {
            gl.viewport(0, 0, source.width, source.height);
        }

        if (clearAlpha)
        {
            gl.clearColor(0, 0, 0, 0);
        }
        else
        {
            gl.clearColor(0, 0, 0, 1);
        }

        gl.clear(gl.COLOR_BUFFER_BIT);

        gl.bufferData(gl.ARRAY_BUFFER, this.vertexData, gl.STATIC_DRAW);
        gl.drawArrays(gl.TRIANGLES, 0, 6);

        gl.bindFramebuffer(gl.FRAMEBUFFER, null);
        gl.bindTexture(gl.TEXTURE_2D, null);
    },

    /**
     * Copy the `source` Render Target to the `target` Render Target, using the
     * given Color Matrix.
     *
     * The difference between this method and `copyFrame` is that this method
     * uses a color matrix shader, where you have full control over the luminance
     * values used during the copy. If you don't need this, you can use the faster
     * `copyFrame` method instead.
     *
     * @method Phaser.Renderer.WebGL.Pipelines.UtilityPipeline#drawFrame
     * @since 3.50.0
     *
     * @param {Phaser.Renderer.WebGL.RenderTarget} source - The source Render Target.
     * @param {Phaser.Renderer.WebGL.RenderTarget} [target] - The target Render Target.
     * @param {boolean} [clearAlpha=true] - Clear the alpha channel when running `gl.clear` on the target?
     * @param {Phaser.Display.ColorMatrix} [colorMatrix] - The Color Matrix to use when performing the draw.
     */
    drawFrame: function (source, target, clearAlpha, colorMatrix)
    {
        if (clearAlpha === undefined) { clearAlpha = true; }
        if (colorMatrix === undefined) { colorMatrix = this.colorMatrix; }

        var gl = this.gl;

        this.set1i('uMainSampler', 0, this.colorMatrixShader);
        this.set1fv('uColorMatrix', colorMatrix.getData(), this.colorMatrixShader);
        this.set1f('uAlpha', colorMatrix.alpha, this.colorMatrixShader);

        gl.activeTexture(gl.TEXTURE0);
        gl.bindTexture(gl.TEXTURE_2D, source.texture);

        if (target)
        {
            gl.viewport(0, 0, target.width, target.height);
            gl.bindFramebuffer(gl.FRAMEBUFFER, target.framebuffer);
            gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, target.texture, 0);
        }
        else
        {
            gl.viewport(0, 0, source.width, source.height);
        }

        if (clearAlpha)
        {
            gl.clearColor(0, 0, 0, 0);
        }
        else
        {
            gl.clearColor(0, 0, 0, 1);
        }

        gl.clear(gl.COLOR_BUFFER_BIT);

        gl.bufferData(gl.ARRAY_BUFFER, this.vertexData, gl.STATIC_DRAW);
        gl.drawArrays(gl.TRIANGLES, 0, 6);

        gl.bindFramebuffer(gl.FRAMEBUFFER, null);
        gl.bindTexture(gl.TEXTURE_2D, null);
    },

    /**
     * Draws the `source1` and `source2` Render Targets to the `target` Render Target
     * using a linear blend effect, which is controlled by the `strength` parameter.
     *
     * @method Phaser.Renderer.WebGL.Pipelines.UtilityPipeline#blendFrames
     * @since 3.50.0
     *
     * @param {Phaser.Renderer.WebGL.RenderTarget} source1 - The first source Render Target.
     * @param {Phaser.Renderer.WebGL.RenderTarget} source2 - The second source Render Target.
     * @param {Phaser.Renderer.WebGL.RenderTarget} [target] - The target Render Target.
     * @param {number} [strength=1] - The strength of the blend.
     * @param {boolean} [clearAlpha=true] - Clear the alpha channel when running `gl.clear` on the target?
     * @param {Phaser.Renderer.WebGL.WebGLShader} [blendShader] - The shader to use during the blend copy.
     */
    blendFrames: function (source1, source2, target, strength, clearAlpha, blendShader)
    {
        if (strength === undefined) { strength = 1; }
        if (clearAlpha === undefined) { clearAlpha = true; }
        if (blendShader === undefined) { blendShader = this.linearShader; }

        var gl = this.gl;

        this.set1i('uMainSampler1', 0, blendShader);
        this.set1i('uMainSampler2', 1, blendShader);
        this.set1f('uStrength', strength, blendShader);

        gl.activeTexture(gl.TEXTURE0);
        gl.bindTexture(gl.TEXTURE_2D, source1.texture);

        gl.activeTexture(gl.TEXTURE1);
        gl.bindTexture(gl.TEXTURE_2D, source2.texture);

        if (target)
        {
            gl.bindFramebuffer(gl.FRAMEBUFFER, target.framebuffer);
            gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, target.texture, 0);
            gl.viewport(0, 0, target.width, target.height);
        }
        else
        {
            gl.viewport(0, 0, source1.width, source1.height);
        }

        if (clearAlpha)
        {
            gl.clearColor(0, 0, 0, 0);
        }
        else
        {
            gl.clearColor(0, 0, 0, 1);
        }

        gl.clear(gl.COLOR_BUFFER_BIT);

        gl.bufferData(gl.ARRAY_BUFFER, this.vertexData, gl.STATIC_DRAW);
        gl.drawArrays(gl.TRIANGLES, 0, 6);

        gl.bindTexture(gl.TEXTURE_2D, null);
    },

    /**
     * Draws the `source1` and `source2` Render Targets to the `target` Render Target
     * using an additive blend effect, which is controlled by the `strength` parameter.
     *
     * @method Phaser.Renderer.WebGL.Pipelines.UtilityPipeline#blendFramesAdditive
     * @since 3.50.0
     *
     * @param {Phaser.Renderer.WebGL.RenderTarget} source1 - The first source Render Target.
     * @param {Phaser.Renderer.WebGL.RenderTarget} source2 - The second source Render Target.
     * @param {Phaser.Renderer.WebGL.RenderTarget} [target] - The target Render Target.
     * @param {number} [strength=1] - The strength of the blend.
     * @param {boolean} [clearAlpha=true] - Clear the alpha channel when running `gl.clear` on the target?
     */
    blendFramesAdditive: function (source1, source2, target, strength, clearAlpha)
    {
        this.blendFrames(source1, source2, target, strength, clearAlpha, this.addShader);
    }

});

module.exports = UtilityPipeline;