import { ShaderProgram } from "../webgl/ShaderProgram";
import { Scene } from "./Scene";
import type { WebGLBufferExt } from "../webgl/Handler";

class Axes extends Scene {
    public size: number;
    public axesBuffer: WebGLBufferExt | null;
    public axesColorBuffer: WebGLBufferExt | null;

    constructor(size: number = 100) {
        super("Axes");

        this.size = size;
        this.axesBuffer = null;
        this.axesColorBuffer = null;
    }

    public override init() {
        this.createAxesBuffer(this.size);
        this.drawMode = this.renderer!.handler.gl!.LINES;
        this.renderer!.handler.addProgram(
            new ShaderProgram("axesShader", {
                uniforms: {
                    projectionViewMatrix: "mat4"
                },
                attributes: {
                    aVertexPosition: "vec3",
                    aVertexColor: "vec4"
                },
                vertexShader: `attribute vec3 aVertexPosition;
            attribute vec4 aVertexColor;
            uniform mat4 projectionViewMatrix;
            varying vec4 vColor;
            void main(void) {
                gl_Position = projectionViewMatrix * vec4(aVertexPosition, 1.0);
                vColor = aVertexColor;
            }`,
                fragmentShader: `precision highp float;
            varying vec4 vColor;
            void main(void) {
                gl_FragColor = vColor;
            }`
            })
        );

        this.renderer?.events.on("forwardpass", this.forward);
    }

    public override onremove() {
        this.renderer?.events.off("forwardpass", this.forward);
    }

    public forward = () => {
        this.renderer!.handler.programs.axesShader.activate().set({
            projectionViewMatrix: this.renderer!.activeCamera!.getProjectionViewMatrix(),
            aVertexPosition: this.axesBuffer,
            aVertexColor: this.axesColorBuffer
        });

        this.renderer!.handler.programs.axesShader.drawArrays(this.drawMode, this.axesBuffer!.numItems);
    };

    public createAxesBuffer(gridSize: number) {
        const vertices = [
            0.0,
            0.0,
            0.0,
            gridSize - 1,
            0.0,
            0.0, // x - R
            0.0,
            0.0,
            0.0,
            0.0,
            gridSize - 1,
            0.0, // y - B
            0.0,
            0.0,
            0.0,
            0.0,
            0.0,
            gridSize - 1 // z - G
        ];

        const colors = [
            1.0,
            0.0,
            0.0,
            1.0,
            1.0,
            0.0,
            0.0,
            1.0, // x - R
            0.0,
            0.0,
            1.0,
            1.0,
            0.0,
            0.0,
            1.0,
            1.0, // y - B
            0.0,
            1.0,
            0.0,
            1.0,
            0.0,
            1.0,
            0.0,
            1.0 // z - G
        ];

        this.axesBuffer = this.renderer!.handler.createArrayBuffer(new Float32Array(vertices), 3, 6);
        this.axesColorBuffer = this.renderer!.handler.createArrayBuffer(new Float32Array(colors), 4, 6);
    }
}

export { Axes };