/**
 * Copyright (c) 2019 mol* contributors, licensed under MIT, See LICENSE file for more info.
 *
 * @author Alexander Rose <alexander.rose@weirdbyte.de>
 */

import { WebGLContext } from 'mol-gl/webgl/context';
import { Texture } from 'mol-gl/webgl/texture';
import { printTextureImage } from 'mol-gl/renderable/util';
import { defaults, ValueCell } from 'mol-util';
import { ValueSpec, AttributeSpec, UniformSpec, Values } from 'mol-gl/renderable/schema';
import { Vec2 } from 'mol-math/linear-algebra';
import { GLRenderingContext } from 'mol-gl/webgl/compat';

export const QuadPositions = new Float32Array([
     1.0,  1.0,  -1.0,  1.0,  -1.0, -1.0, // First triangle
    -1.0, -1.0,   1.0, -1.0,   1.0,  1.0  // Second triangle
])

export const QuadSchema = {
    drawCount: ValueSpec('number'),
    instanceCount: ValueSpec('number'),
    aPosition: AttributeSpec('float32', 2, 0),
    uQuadScale: UniformSpec('v2'),
}

export const QuadValues: Values<typeof QuadSchema> = {
    drawCount: ValueCell.create(6),
    instanceCount: ValueCell.create(1),
    aPosition: ValueCell.create(QuadPositions),
    uQuadScale: ValueCell.create(Vec2.create(1, 1)),
}

//

function getArrayForTexture(gl:GLRenderingContext, texture: Texture, size: number) {
    switch (texture.type) {
        case gl.UNSIGNED_BYTE: return new Uint8Array(size)
        case gl.FLOAT: return new Float32Array(size)
    }
    throw new Error('unknown/unsupported texture type')
}

export function readTexture(ctx: WebGLContext, texture: Texture, width?: number, height?: number) {
    const { gl, framebufferCache } = ctx
    width = defaults(width, texture.width)
    height = defaults(height, texture.height)
    const size = width * height * 4
    const framebuffer = framebufferCache.get('read-texture').value
    const array = getArrayForTexture(gl, texture, size)
    framebuffer.bind()
    texture.attachFramebuffer(framebuffer, 0)
    ctx.readPixels(0, 0, width, height, array)

    return { array, width, height }
}

export function printTexture(ctx: WebGLContext, texture: Texture, scale: number) {
    printTextureImage(readTexture(ctx, texture), scale)
}