/*
 * Copyright (C) 2018 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "filaweb.h"

#include <filament/Engine.h>
#include <filament/IndexBuffer.h>
#include <filament/Material.h>
#include <filament/MaterialInstance.h>
#include <filament/RenderableManager.h>
#include <filament/Scene.h>
#include <filament/TransformManager.h>
#include <filament/VertexBuffer.h>
#include <filament/View.h>

#include <cmath>

using namespace filament;

using utils::Entity;
using utils::EntityManager;

struct TriangleApp {
    VertexBuffer* vb;
    IndexBuffer* ib;
    Material* mat;
    Camera* cam;
    Entity renderable;
};

struct Vertex {
    math::float2 position;
    uint32_t color;
};

static const Vertex TRIANGLE_VERTICES[3] = {
    {{1, 0}, 0xffff0000u},
    {{cos(M_PI * 2 / 3), sin(M_PI * 2 / 3)}, 0xff00ff00u},
    {{cos(M_PI * 4 / 3), sin(M_PI * 4 / 3)}, 0xff0000ffu},
};

static constexpr uint16_t TRIANGLE_INDICES[3] = { 0, 1, 2 };

static constexpr uint8_t BAKED_COLOR_PACKAGE[] = {
    #include "generated/material/bakedColor.inc"
};

static TriangleApp app;

void setup(Engine* engine, View* view, Scene* scene) {
    view->setClearColor({0.1, 0.125, 0.25, 1.0});
    view->setPostProcessingEnabled(false);
    view->setDepthPrepass(filament::View::DepthPrepass::DISABLED);
    static_assert(sizeof(Vertex) == 12, "Strange vertex size.");
    app.vb = VertexBuffer::Builder()
            .vertexCount(3)
            .bufferCount(1)
            .attribute(VertexAttribute::POSITION, 0, VertexBuffer::AttributeType::FLOAT2, 0, 12)
            .attribute(VertexAttribute::COLOR, 0, VertexBuffer::AttributeType::UBYTE4, 8, 12)
            .normalized(VertexAttribute::COLOR)
            .build(*engine);
    app.vb->setBufferAt(*engine, 0,
            VertexBuffer::BufferDescriptor(TRIANGLE_VERTICES, 36, nullptr));
    app.ib = IndexBuffer::Builder()
            .indexCount(3)
            .bufferType(IndexBuffer::IndexType::USHORT)
            .build(*engine);
    app.ib->setBuffer(*engine,
            IndexBuffer::BufferDescriptor(TRIANGLE_INDICES, 6, nullptr));
    app.mat = Material::Builder()
            .package((void*) BAKED_COLOR_PACKAGE, sizeof(BAKED_COLOR_PACKAGE))
            .build(*engine);
    app.renderable = EntityManager::get().create();
    RenderableManager::Builder(1)
            .boundingBox({{ -1, -1, -1 }, { 1, 1, 1 }})
            .material(0, app.mat->getDefaultInstance())
            .geometry(0, RenderableManager::PrimitiveType::TRIANGLES, app.vb, app.ib, 0, 3)
            .culling(false)
            .receiveShadows(false)
            .castShadows(false)
            .build(*engine, app.renderable);
    scene->addEntity(app.renderable);
    app.cam = engine->createCamera();
    view->setCamera(app.cam);
};

void animate(Engine* engine, View* view, double now) {
    constexpr float ZOOM = 1.5f;
    const uint32_t w = view->getViewport().width;
    const uint32_t h = view->getViewport().height;
    const float aspect = (float) w / h;
    app.cam->setProjection(Camera::Projection::ORTHO,
        -aspect * ZOOM, aspect * ZOOM,
        -ZOOM, ZOOM, 0, 1);
    auto& tcm = engine->getTransformManager();
    tcm.setTransform(tcm.getInstance(app.renderable),
            math::mat4f::rotate(now, math::float3{0, 0, 1}));
};

// This is called only after the JavaScript layer has created a WebGL 2.0 context and all assets
// have been downloaded.
extern "C" void launch() {
    filaweb::Application::get()->run(setup, animate);
}

// The main() entry point is implicitly called after JIT compilation, but potentially before the
// WebGL context has been created or assets have finished loading.
int main() { }