/*
 * 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 "filamesh.h"
#include "filaweb.h"

#include <filament/Engine.h>
#include <filament/IndexBuffer.h>
#include <filament/LightManager.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 <utils/Entity.h>
#include <utils/EntityManager.h>

#include <math/vec3.h>

using namespace filament;
using namespace math;
using namespace std;
using namespace utils;

using MagFilter = TextureSampler::MagFilter;
using WrapMode = TextureSampler::WrapMode;
using Format = Texture::InternalFormat;

struct SuzanneApp {
    Filamesh filamesh;
    Material* mat;
    MaterialInstance* mi;
    Camera* cam;
    Entity sun;
    Entity ptlight[4];
};

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

static SuzanneApp app;

static Texture* setTextureParameter(Engine& engine, filaweb::Asset& asset, string name,
        TextureSampler const &sampler, Format internalFormat) {

    const auto destructor = [](void* buffer, size_t size, void* user) {
        auto asset = (filaweb::Asset*) user;
        asset->data.reset();
    };

    Texture::PixelBufferDescriptor pb(
            asset.data.get(), asset.nbytes, Texture::Format::RGBA, Texture::Type::UBYTE,
            destructor, &asset);

    // TODO: Since we use a Canvas 2D to decode textures, they are always 4-component. We should
    // manually reshape the data here to improve footprint.
    if (internalFormat == Format::R8) {
        internalFormat = Format::RGBA8;
    }

    auto texture = Texture::Builder()
            .width(asset.width)
            .height(asset.height)
            .sampler(Texture::Sampler::SAMPLER_2D)
            .format(internalFormat)
            .build(engine);

    texture->setImage(engine, 0, std::move(pb));
    app.mi->setParameter(name.c_str(), texture, sampler);
    return texture;
}

void setup(Engine* engine, View* view, Scene* scene) {

    // Create material.
    app.mat = Material::Builder()
            .package((void*) MATERIAL_LIT_PACKAGE, sizeof(MATERIAL_LIT_PACKAGE))
            .build(*engine);
    app.mi = app.mat->createInstance();
    app.mi->setParameter("clearCoat", 0.0f);

    // Move raw asset data from JavaScript to C++ static storage. Their held data will be freed via
    // BufferDescriptor callbacks after Filament creates the corresponding GPU objects.
    static auto mesh = filaweb::getRawFile("mesh");
    static auto albedo = filaweb::getTexture("albedo");
    static auto metallic = filaweb::getTexture("metallic");
    static auto roughness = filaweb::getTexture("roughness");
    static auto normal = filaweb::getTexture("normal");
    static auto ao = filaweb::getTexture("ao");

    // Create mesh.
    printf("%s: %d bytes\n", "mesh", mesh.nbytes);
    const uint8_t* mdata = mesh.data.get();
    const auto destructor = [](void* buffer, size_t size, void* user) {
        auto asset = (filaweb::Asset*) user;
        asset->data.reset();
    };
    app.filamesh = decodeMesh(*engine, mdata, 0, app.mi, destructor, &mesh);
    scene->addEntity(app.filamesh->renderable);

    // Create textures.
    TextureSampler sampler(MagFilter::LINEAR, WrapMode::CLAMP_TO_EDGE);
    auto setTexture = [engine, sampler] (filaweb::Asset& asset, const char* name, Format format) {
        printf("%s: %d x %d\n", name, asset.width, asset.height);
        setTextureParameter(*engine, asset, name, sampler, format);
    };
    setTexture(albedo, "albedo", Format::SRGB8_A8);
    setTexture(metallic, "metallic", Format::R8);
    setTexture(roughness, "roughness", Format::R8);
    setTexture(normal, "normal", Format::RGBA8);
    setTexture(ao, "ao", Format::R8);

    // Create the sun.
    auto& em = EntityManager::get();
    app.sun = em.create();
    LightManager::Builder(LightManager::Type::SUN)
            .color(Color::toLinear<ACCURATE>({ 0.98f, 0.92f, 0.89f }))
            .intensity(110000)
            .direction({ 0.7, -1, -0.8 })
            .sunAngularRadius(1.2f)
            .castShadows(true)
            .build(*engine, app.sun);
    scene->addEntity(app.sun);

    // Create point lights.
    em.create(4, app.ptlight);
    LightManager::Builder(LightManager::Type::POINT)
            .color(Color::toLinear<ACCURATE>({0.98f, 0.92f, 0.89f}))
            .intensity(LightManager::EFFICIENCY_LED, 300.0f)
            .position({0.0f, -0.2f, -3.0f})
            .falloff(4.0f)
            .build(*engine, app.ptlight[0]);
    LightManager::Builder(LightManager::Type::POINT)
            .color(Color::toLinear<ACCURATE>({0.98f, 0.12f, 0.19f}))
            .intensity(LightManager::EFFICIENCY_LED, 200.0f)
            .position({0.6f, 0.6f, -3.2f})
            .falloff(2.0f)
            .build(*engine, app.ptlight[1]);
    LightManager::Builder(LightManager::Type::POINT)
            .color(Color::toLinear<ACCURATE>({0.18f, 0.12f, 0.89f}))
            .intensity(LightManager::EFFICIENCY_LED, 200.0f)
            .position({-0.6f, 0.6f, -3.2f})
            .falloff(2.0f)
            .build(*engine, app.ptlight[2]);
    LightManager::Builder(LightManager::Type::POINT)
            .color(Color::toLinear<ACCURATE>({0.88f, 0.82f, 0.29f}))
            .intensity(LightManager::EFFICIENCY_LED, 200.0f)
            .position({0.0f, 1.5f, -3.5f})
            .falloff(2.0f)
            .build(*engine, app.ptlight[3]);
    scene->addEntity(app.ptlight[0]);
    scene->addEntity(app.ptlight[1]);
    scene->addEntity(app.ptlight[2]);
    scene->addEntity(app.ptlight[3]);

    // Create skybox and image-based light source.
    auto skylight = filaweb::getSkyLight(*engine, "syferfontein_18d_clear_2k");
    scene->setIndirectLight(skylight.indirectLight);
    scene->setSkybox(skylight.skybox);
    skylight.indirectLight->setRotation(
            mat3f::rotate(M_PI, float3{ 0, 1, 0 }));

    app.cam = engine->createCamera();
    app.cam->setExposure(16.0f, 1 / 125.0f, 100.0f);
    app.cam->lookAt(float3{0}, float3{0, 0, -4});
    view->setCamera(app.cam);
    view->setClearColor({0.1, 0.125, 0.25, 1.0});
};

void animate(Engine* engine, View* view, double now) {
    using Fov = Camera::Fov;
    const uint32_t width = view->getViewport().width;
    const uint32_t height = view->getViewport().height;
    double ratio = double(width) / height;
    app.cam->setProjection(45.0, ratio, 0.1, 50.0, ratio < 1 ? Fov::HORIZONTAL : Fov::VERTICAL);
    auto& tcm = engine->getTransformManager();
    tcm.setTransform(tcm.getInstance(app.filamesh->renderable),
        mat4f{mat3f{1.0}, float3{0.0f, 0.0f, -4.0f}} *
        mat4f::rotate(now, math::float3{0, 1, 0}));
};

// 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() { }