import * as Assets from "./assets.js";
import {Vec2, Vec3, Vec4} from "./common.js";

export function fullscreenCanvas(gfx: Graphics, id: string) {
    const canvas  = document.getElementById(id) as HTMLCanvasElement;
    canvas.width  = window.innerWidth;
    canvas.height = window.innerHeight;
    gfx.ctx.viewport(0, 0, canvas.width, canvas.height);
}

function createShader(ctx: WebGL2RenderingContext, type: GLenum, source: string): WebGLShader {
    var shader = ctx.createShader(type);
    if (!shader) {
        throw new Error("Couldn't create shader: " + type);
    }

    ctx.shaderSource(shader, source);
    ctx.compileShader(shader);

    var success = ctx.getShaderParameter(shader, ctx.COMPILE_STATUS);
    if (!success) {
        console.log(ctx.getShaderInfoLog(shader));
        ctx.deleteShader(shader);
        throw new Error("Couldn't compile shader: " + type);
    }

    return shader;
}

function createProgram(ctx: WebGL2RenderingContext, vertexShaderSource: string | null, fragmentShaderSource: string | null): WebGLProgram {
    var program = ctx.createProgram();

    if (vertexShaderSource !== null) {
        const vs = createShader(ctx, ctx.VERTEX_SHADER, vertexShaderSource);
        ctx.attachShader(program, vs);
    }

    if (fragmentShaderSource !== null) {
        const fs = createShader(ctx, ctx.FRAGMENT_SHADER, fragmentShaderSource);
        ctx.attachShader(program, fs);
    }

    ctx.linkProgram(program);

    var success = ctx.getProgramParameter(program, ctx.LINK_STATUS);
    if (!success) {
        console.log(ctx.getProgramInfoLog(program));
        ctx.deleteProgram(program);
        throw new Error("Failed to create program!");
    }

    return program;
}

export enum DrawTag {
    ISO,
}

export interface Drawable {
    fill: Texture | Assets.Color;
    attribs: string[];
    tags: Array<DrawTag>;

    data: Array<number>;
    vertexStride: number;
    stride: number;
}

export class Graphics {
    ctx: WebGL2RenderingContext;
    program: WebGLProgram;
    attribs: Map<string, Attribute> = new Map();
    uniforms: Map<string, WebGLUniformLocation> = new Map();
    vao: WebGLVertexArrayObject;
    vbo: WebGLBuffer;

    toRender: Array<Drawable> = [];
    texCount: number = 0;

    constructor(ctx: WebGL2RenderingContext, vs: string, fs: string) {
        this.ctx = ctx;
        this.program = createProgram(ctx, vs, fs);
        this.vao = ctx.createVertexArray();
        this.vbo = ctx.createBuffer();

        ctx.bindVertexArray(this.vao);
        ctx.viewport(0, 0, ctx.canvas.width, ctx.canvas.height);
        ctx.useProgram(this.program);

        ctx.blendFunc(ctx.SRC_ALPHA, ctx.ONE_MINUS_SRC_ALPHA);
        ctx.enable(ctx.BLEND);
    }

    clear(r: number, g: number, b: number, a: number) {
        this.ctx.clearColor(r, g, b, a);
        this.ctx.clear(this.ctx.COLOR_BUFFER_BIT);
    }

    createAttribute(name: string): Attribute {
        const attrib = new Attribute(this.ctx, this.program, name);
        this.attribs.set(name, attrib);
        return attrib;
    }

    getAttribute(name: string): Attribute {
        const attrib = this.attribs.get(name);

        if (attrib === undefined)
            throw new Error("Tried to get uninitialized attribute: " + name);

        return attrib;
    }

    createUniform(name: string) {
        const loc = this.ctx.getUniformLocation(this.program, name);

        if (loc === null)
            throw new Error("Couldn't get location for uniform: " + name);

        this.uniforms.set(name, loc);
    }

    getUniform(name: string): WebGLUniformLocation {
        const loc = this.uniforms.get(name);

        if (loc === undefined)
            throw new Error("Tried to get uninitialized uniform: " + name);

        return loc;
    }

    draw() {
        for (let o of this.toRender) {
            this.ctx.bindBuffer(this.ctx.ARRAY_BUFFER, this.vbo);
            this.ctx.bufferData(this.ctx.ARRAY_BUFFER, new Float32Array(o.data), this.ctx.STATIC_DRAW);

            let aid = 0;
            for (let a of o.attribs) {
                let attr = this.getAttribute(a);
                if (!attr.formatted)
                    throw new Error("Tried to use unformatted attribute!");
                
                this.ctx.enableVertexAttribArray(attr.loc);
                this.ctx.vertexAttribPointer(attr.loc, attr.size, attr.type, attr.normalized, o.stride, aid * 4);
                aid += attr.size;
            }

            // Generalize the tag uniforms aka. don't hard code them
            for (let t of o.tags) {
                switch (t) {
                    case DrawTag.ISO: {
                        this.ctx.uniform1ui(this.getUniform("u_isIso"), 1);
                        break;
                    }
                }
            }

            if (o.fill instanceof Texture)
            {
                this.ctx.uniform1i(this.getUniform("u_isTex"), 1);
                o.fill.bind(this);
            }

            this.ctx.drawArrays(this.ctx.TRIANGLES, 0, o.data.length / o.vertexStride);

            if (o.fill instanceof Texture)
            {
                this.ctx.uniform1i(this.getUniform("u_isTex"), 0);
                o.fill.unbind(this);
            }

            for (let t of o.tags) {
                switch (t) {
                    case DrawTag.ISO: {
                        this.ctx.uniform1ui(this.getUniform("u_isIso"), 0);
                        break;
                    }
                }
            }

        }

        // TODO: Maybe add persistent rendering?
        this.toRender = [];
    }
}

export class Attribute {
    loc: GLint;
    formatted: boolean = false;

    size: GLint = 0;
    type: GLenum = 0;
    offset: GLintptr = 0;
    normalized: GLboolean = false;

    constructor(ctx: WebGL2RenderingContext, program: WebGLProgram, name: string) {
        this.loc = ctx.getAttribLocation(program, name);
    }

    format(
        size: GLint,
        type: GLenum,
        normalized: GLboolean,
        offset: GLintptr)
    {
        this.size = size;
        this.type = type;
        this.normalized = normalized;
        this.offset = offset;

        this.formatted = true;
    }
}

export class Texture {
    tex: WebGLTexture | null;
    texId: number;
    width: number = 0;
    height: number = 0;

    constructor(texId: number, tex: WebGLTexture, width: number, height: number) {
        this.height = height;
        this.width = width;
        this.tex = tex;
        this.texId = texId;
    }

    // TODO: Load sprite sheet only once
    // TODO: Allow changing sprite size
    static async load(gfx: Graphics, path: string): Promise<Texture> {
        let image = await loadTexture(path);
        
        let tex = gfx.ctx.createTexture();
        gfx.ctx.bindTexture(gfx.ctx.TEXTURE_2D, tex);
        gfx.ctx.texImage2D(gfx.ctx.TEXTURE_2D, 0, gfx.ctx.RGBA, gfx.ctx.RGBA, gfx.ctx.UNSIGNED_BYTE, image);
        gfx.ctx.texParameteri(gfx.ctx.TEXTURE_2D, gfx.ctx.TEXTURE_MAG_FILTER, gfx.ctx.NEAREST);
        gfx.ctx.texParameteri(gfx.ctx.TEXTURE_2D, gfx.ctx.TEXTURE_MIN_FILTER, gfx.ctx.NEAREST);
        gfx.ctx.bindTexture(gfx.ctx.TEXTURE_2D, null);

        gfx.texCount += 1;
        return new Texture(gfx.texCount, tex, image.width, image.height);
    }

    bind(gfx: Graphics) {
        gfx.ctx.bindTexture(gfx.ctx.TEXTURE_2D, this.tex);
    }

    unbind(gfx: Graphics) {
        gfx.ctx.bindTexture(gfx.ctx.TEXTURE_2D, null);
    }
}

async function loadTexture(path: string): Promise<HTMLImageElement> {
    return new Promise(resolve => {
        const img = new Image();
        img.addEventListener("load", () => {
            resolve(img);
        })
        img.src = path;
    });
}

export class Camera {
    dt: number = 0;
    position: Vec3;
    movement: Vec4;
    speed: number = 600;

    constructor(position: Vec3) {
        this.position = position;
        this.movement = new Vec4(0, 0, 0, 0);
    }

    update(dt: number) {
        this.dt = dt;

        let newPosition = this.movement.multScalarNew(this.dt);
        this.position.x += (newPosition.x + newPosition.y) * this.speed;
        this.position.y += (newPosition.z + newPosition.w) * this.speed;
    }
}