import { gl } from './Renderer.js'

export class Shader {

    #vertexShader;
    #fragmentShader;
    #program;
    #attributes;
    #uniforms;

    constructor(vertexCode, fragmentCode) {

        this.#vertexShader = gl.createShader(gl.VERTEX_SHADER)
        this.#fragmentShader = gl.createShader(gl.FRAGMENT_SHADER)

        gl.shaderSource(this.#vertexShader, vertexCode)
        gl.shaderSource(this.#fragmentShader, fragmentCode)

        gl.compileShader(this.#vertexShader)
        if (!gl.getShaderParameter(this.#vertexShader, gl.COMPILE_STATUS)) {
            console.error('Failed to compile vertex shader!', gl.getShaderInfoLog(this.#vertexShader))
            return
        }

        gl.compileShader(this.#fragmentShader)
        if (!gl.getShaderParameter(this.#fragmentShader, gl.COMPILE_STATUS)) {
            console.error('Failed to compile fragment shader!', gl.getShaderInfoLog(this.#fragmentShader))
            return
        }

        this.#program = gl.createProgram()
        gl.attachShader(this.#program, this.#vertexShader)
        gl.attachShader(this.#program, this.#fragmentShader)
        gl.linkProgram(this.#program)
        if (!gl.getProgramParameter(this.#program, gl.LINK_STATUS)) {
            console.error("Failed to link shader program!", gl.getProgramInfoLog(this.#program));
            return
        }

        gl.validateProgram(this.#program);
        if (!gl.getProgramParameter(this.#program, gl.VALIDATE_STATUS)) {
            console.error("Failed to validate shader program!", gl.getProgramInfoLog(this.#program));
            return
        }

        this.#attributes = []
        this.#uniforms = {} 

        vertexCode.split('\n').forEach((line) => {
            const tokens = line.trim().split(" ")
            if (tokens.length != 3) return
            if (tokens[0] === "attribute") {
                this.#attributes.push(tokens[2].replace(/\s+/g, '').split(';')[0])
            }
            if (tokens[0] == "uniform") {
                const loc = gl.getUniformLocation(this.#program, tokens[2].replace(/\s+/g, '').split(';')[0])
                this.#uniforms[tokens[2].replace(/\s+/g, '').split(';')[0]] = loc
            }
        })

    }

    start() {
        gl.useProgram(this.#program)
        for (let i = 0; i < this.#attributes.length; i++) {
            gl.bindAttribLocation(this.#program, i, this.#attributes[i])
        }
    }

    stop() {
        gl.useProgram(null)
    }

    loadFloat(name, float) {
        gl.uniform1f(this.#uniforms[name], float)
    }

    loadInt(name, int) {
        gl.uniform1i(this.#uniforms[name], int)
    }

    loadVec2(name, v) {
        gl.uniform2f(this.#uniforms[name], v.x, v.y)
    }

    loadVec3(name, v) {
        gl.uniform3f(this.#uniforms[name], v.x, v.y, v.z)
    }

    loadMat4(name, m) {
        if(this.#uniforms[name] == undefined) return;
        gl.uniformMatrix4fv(this.#uniforms[name], gl.FALSE, m.data)
    }

    loadBool(name, bool) {
        gl.uniform1f(this.#uniforms[name], bool ? 1 : 0)
    }

}