// pathfinder/client/src/gl-utils.ts
//
// Copyright © 2017 The Pathfinder Project Developers.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

import * as glmatrix from 'gl-matrix';

import {assert, UINT32_SIZE, unwrapNull} from './utils';
import { DemoView } from './view';

export type WebGLVertexArrayObject = any;

export interface AttributeMap {
    [attributeName: string]: number;
}

export interface UniformMap {
    [uniformName: string]: WebGLUniformLocation;
}

export const QUAD_ELEMENTS: Uint8Array = new Uint8Array([2, 0, 1, 1, 3, 2]);

export function createFramebufferColorTexture(view: DemoView, size: glmatrix.vec2): WebGLTexture {
    // Firefox seems to have a bug whereby textures don't get marked as initialized when cleared
    // if they're anything other than the first attachment of an FBO. To work around this, supply
    // zero data explicitly when initializing the texture.
    const zeroes = new Uint8Array(size[0] * size[1] * UINT32_SIZE);
    const texture = unwrapNull(view.gl.createTexture());
    view.gl.activeTexture(view.gl.TEXTURE0);
    view.gl.bindTexture(view.gl.TEXTURE_2D, texture);
    view.gl.texImage2D(view.gl.TEXTURE_2D,
                  0,
                  view.colorAlphaFormat,
                  size[0],
                  size[1],
                  0,
                  view.colorAlphaFormat,
                  view.gl.UNSIGNED_BYTE,
                  zeroes);
    setTextureParameters(view.gl, view.gl.NEAREST);
    return texture;
}

export function createFramebufferDepthTexture(gl: WebGLRenderingContext, size: glmatrix.vec2):
                                              WebGLTexture {
    const texture = unwrapNull(gl.createTexture());
    gl.activeTexture(gl.TEXTURE0);
    gl.bindTexture(gl.TEXTURE_2D, texture);
    gl.texImage2D(gl.TEXTURE_2D,
                  0,
                  gl.DEPTH_COMPONENT,
                  size[0],
                  size[1],
                  0,
                  gl.DEPTH_COMPONENT,
                  gl.UNSIGNED_INT,
                  null);
    setTextureParameters(gl, gl.NEAREST);
    return texture;
}

export function setTextureParameters(gl: WebGLRenderingContext, filter: number) {
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, filter);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, filter);
}

export function createFramebuffer(gl: WebGLRenderingContext,
                                  drawBuffersExt: any,
                                  colorAttachments: WebGLTexture[],
                                  depthAttachment: WebGLTexture | null):
                                  WebGLFramebuffer {
    const framebuffer = unwrapNull(gl.createFramebuffer());
    gl.bindFramebuffer(gl.FRAMEBUFFER, framebuffer);

    const colorAttachmentCount = colorAttachments.length;
    for (let colorAttachmentIndex = 0;
         colorAttachmentIndex < colorAttachmentCount;
         colorAttachmentIndex++) {
        gl.framebufferTexture2D(gl.FRAMEBUFFER,
                                drawBuffersExt[`COLOR_ATTACHMENT${colorAttachmentIndex}_WEBGL`],
                                gl.TEXTURE_2D,
                                colorAttachments[colorAttachmentIndex],
                                0);
    }

    if (depthAttachment != null) {
        gl.framebufferTexture2D(gl.FRAMEBUFFER,
                                gl.DEPTH_ATTACHMENT,
                                gl.TEXTURE_2D,
                                depthAttachment,
                                0);
    }

    assert(gl.checkFramebufferStatus(gl.FRAMEBUFFER) === gl.FRAMEBUFFER_COMPLETE,
           "Framebuffer was incomplete!");
    return framebuffer;
}