/*
 * 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 "common/arguments.h"

#include <filament/Engine.h>
#include <filament/LightManager.h>
#include <filament/Material.h>
#include <filament/RenderableManager.h>
#include <filament/Scene.h>
#include <filament/TransformManager.h>
#include <filament/View.h>

#include <utils/EntityManager.h>

#include <filameshio/MeshReader.h>

#include <filamentapp/Config.h>
#include <filamentapp/FilamentApp.h>

#include <getopt/getopt.h>

#include <iostream>
#include <string>// for printing usage/help

#include "generated/resources/resources.h"
#include "generated/resources/monkey.h"

using namespace filament;
using namespace filamesh;
using namespace filament::math;

using Backend = Engine::Backend;

struct App {
    Config config;
    utils::Entity light;
    Material* material;
    MaterialInstance* materialInstance;
    MeshReader::Mesh mesh;
    mat4f transform;
};

static const char* IBL_FOLDER = "assets/ibl/lightroom_14b";

static void printUsage(char* name) {
    std::string exec_name(utils::Path(name).getName());
    std::string usage(
            "EXEC renders a simple PBR example\n"
            "Usage:\n"
            "    EXEC [options]\n"
            "Options:\n"
            "   --help, -h\n"
            "       Prints this message\n\n"
            "API_USAGE"
    );
    const std::string from("EXEC");
    for (size_t pos = usage.find(from); pos != std::string::npos; pos = usage.find(from, pos)) {
        usage.replace(pos, from.length(), exec_name);
    }
    const std::string apiUsage("API_USAGE");
    for (size_t pos = usage.find(apiUsage); pos != std::string::npos; pos = usage.find(apiUsage, pos)) {
        usage.replace(pos, apiUsage.length(), samples::getBackendAPIArgumentsUsage());
    }
    std::cout << usage;
}

static int handleCommandLineArguments(int argc, char* argv[], App* app) {
    static constexpr const char* OPTSTR = "ha:";
    static const struct option OPTIONS[] = {
            { "help", no_argument,       nullptr, 'h' },
            { "api",  required_argument, nullptr, 'a' },
            { nullptr, 0,                nullptr, 0 }
    };
    int opt;
    int option_index = 0;
    while ((opt = getopt_long(argc, argv, OPTSTR, OPTIONS, &option_index)) >= 0) {
        std::string arg(optarg ? optarg : "");
        switch (opt) {
            default:
            case 'h':
                printUsage(argv[0]);
                exit(0);
            case 'a':
                app->config.backend = samples::parseArgumentsForBackend(arg);
                break;
        }
    }
    return optind;
}

int main(int argc, char** argv) {
    App app;
    app.config.title = "hellopbr";
    app.config.iblDirectory = FilamentApp::getRootAssetsPath() + IBL_FOLDER;
    handleCommandLineArguments(argc, argv, &app);

    auto setup = [config=app.config, &app](Engine* engine, View* view, Scene* scene) {
        auto& tcm = engine->getTransformManager();
        auto& rcm = engine->getRenderableManager();
        auto& em = utils::EntityManager::get();

        // Instantiate material.
        app.material = Material::Builder()
            .package(RESOURCES_AIDEFAULTMAT_DATA, RESOURCES_AIDEFAULTMAT_SIZE).build(*engine);
        auto mi = app.materialInstance = app.material->createInstance();
        mi->setParameter("baseColor", RgbType::LINEAR, float3{0.8});
        mi->setParameter("metallic", 1.0f);
        mi->setParameter("roughness", 0.4f);
        mi->setParameter("reflectance", 0.5f);

        // Add geometry into the scene.
        app.mesh = MeshReader::loadMeshFromBuffer(engine, MONKEY_SUZANNE_DATA, nullptr, nullptr, mi);
        auto ti = tcm.getInstance(app.mesh.renderable);
        app.transform = mat4f{ mat3f(1), float3(0, 0, -4) } * tcm.getWorldTransform(ti);
        rcm.setCastShadows(rcm.getInstance(app.mesh.renderable), false);
        scene->addEntity(app.mesh.renderable);

        // Add light sources into the scene.
        app.light = em.create();
        LightManager::Builder(LightManager::Type::SUN)
                .color(Color::toLinear<ACCURATE>(sRGBColor(0.98f, 0.92f, 0.89f)))
                .intensity(110000)
                .direction({ 0.7, -1, -0.8 })
                .sunAngularRadius(1.9f)
                .castShadows(false)
                .build(*engine, app.light);
        scene->addEntity(app.light);
    };

    auto cleanup = [&app](Engine* engine, View*, Scene*) {
        engine->destroy(app.light);
        engine->destroy(app.mesh.renderable);
        engine->destroy(app.materialInstance);
        engine->destroy(app.material);
    };

    FilamentApp::get().animate([&app](Engine* engine, View* view, double now) {
        auto& tcm = engine->getTransformManager();
        auto ti = tcm.getInstance(app.mesh.renderable);
        tcm.setTransform(ti, app.transform * mat4f::rotation(now, float3{ 0, 1, 0 }));
    });

    FilamentApp::get().run(app.config, setup, cleanup);

    return 0;
}