//
//  manager_test.cxx
//  graphics
//
//  Created by Sam Jaffe on 6/6/19.
//  Copyright © 2019 Sam Jaffe. All rights reserved.
//

#include <gmock/gmock.h>

#include "../src/helper.hpp"
#include "game/graphics/manager.hpp"
#include "game/graphics/material.hpp"
#include "game/graphics/shader.hpp"
#include "game/graphics/shader_program.hpp"
#include "game/graphics/texture.hpp"

using testing::AllOf;
using testing::AnyNumber;
using testing::Eq;
using testing::Ge;
using testing::Le;
using testing::Ne;
using testing::SizeIs;
using testing::_;

struct mock_manager_impl : graphics::manager {
  using shader = graphics::shader;
  using shader_program = graphics::shader_program;
  using texture = graphics::texture;

  MOCK_CONST_METHOD2(compile_shader,
                     shader(graphics::shaders::type, std::string const &));
  MOCK_CONST_METHOD2(compile_program,
                     shader_program(identity<shader>, identity<shader>));
  shader compile(graphics::shaders::type t, std::string const & s) const {
    return compile_shader(t, s);
  }
  shader_program compile(identity<shader> f, identity<shader> v) const {
    return compile_program(f, v);
  }
  MOCK_CONST_METHOD3(compile, texture(graphics::textures::format, math::vec2i,
                                      void const *));
};

template <typename T> identity<T> cast(unsigned int id) {
  return *reinterpret_cast<identity<T> *>(&id);
}

auto cast_p(unsigned int id) { return cast<graphics::shader_program>(id); }

class ManagerTest : public testing::Test {
public:
  void SetUp() override;

  mock_manager_impl mock;

private:
  struct {
    graphics::texture operator()(math::vec2i const & sz) { return {++i, sz}; }
    unsigned int i{0};
  } next_tex;
};

void ManagerTest::SetUp() {
  using testing::Invoke;
  using testing::WithArg;
  // Start with a new set of IDs
  ON_CALL(mock, compile(_, _, _))
      .WillByDefault(WithArg<1>(Invoke(std::ref(next_tex))));
}

TEST_F(ManagerTest, DoesNotGreedilyCompile) {
  EXPECT_CALL(mock, compile(_, _, _)).Times(0);
  EXPECT_CALL(mock, compile_shader(_, _)).Times(0);
  EXPECT_CALL(mock, compile_program(_, _)).Times(0);
}

using MaterialTest = ManagerTest;

// TEST_F(MaterialTest, ThrowsExceptionIfNoTexOrUniform) {
//  EXPECT_CALL(mock, compile(_, _, _)).Times(AnyNumber());
//  // TODO (sjaffe): Throw a specific exception here, since throw; kills us
//  EXPECT_ANY_THROW(mock.get(cast_p(1), "", ""));
//}

TEST_F(MaterialTest, GeneratesUniformTexturesIfNoTexFile) {
  using graphics::materials::uniform;
  EXPECT_CALL(mock, compile(_, make_vector(1, 1), _)).Times(3);
  EXPECT_NO_THROW(mock.get(cast_p(1), "", "u_normalMap"));
}

TEST_F(MaterialTest, CreatedMaterialCanBeRefetched) {
  using graphics::materials::uniform;
  EXPECT_CALL(mock, compile(_, make_vector(1, 1), _)).Times(3);
  auto material_id = mock.get(cast_p(1), "", "u_normalMap");
  auto material = mock.get(material_id);
  // Ensure that the material is the 'same one' i.e.
  // mock.get(mock.get(id)) == mock.get(id)
  EXPECT_THAT(material, Eq(material_id));
}

TEST_F(MaterialTest, UniformMaterialIsOneByOne) {
  using graphics::materials::uniform;
  EXPECT_CALL(mock, compile(_, make_vector(1, 1), _)).Times(3);
  auto material = mock.get(mock.get(cast_p(1), "", "u_normalMap"));
  // Uniforms are always sized 1x1
  EXPECT_THAT(material.size, Eq(make_vector(1, 1)));
}

TEST_F(MaterialTest, UniformMaterialHasDataBindingToNormalTex) {
  using graphics::materials::uniform;
  EXPECT_CALL(mock, compile(_, make_vector(1, 1), _)).Times(3);
  auto material = mock.get(mock.get(cast_p(1), "", "u_normalMap"));
  EXPECT_THAT(material.uniforms, SizeIs(1));
  // Because we never initialize any textures, we are within the first three
  // texture ID units.
  EXPECT_THAT(material.uniforms[0].texture.id, AllOf(Ge(1), Le(3)));
  // Test the mapping from "u_normalMap" to uniform::NORMAL
  EXPECT_THAT(material.uniforms[0].uniform_id, Eq(uniform::NORMAL));
}

TEST_F(MaterialTest, DifferentProgramMakesDifferentMaterial) {
  using graphics::materials::uniform;
  EXPECT_CALL(mock, compile(_, make_vector(1, 1), _)).Times(3);
  auto id_1 = mock.get(cast_p(1), "", "u_normalMap");
  auto id_2 = mock.get(cast_p(2), "", "u_normalMap");
  EXPECT_THAT(id_1, Ne(id_2));
}

TEST_F(MaterialTest, DifferentProgramDoesntChangeUniformId) {
  using graphics::materials::uniform;
  EXPECT_CALL(mock, compile(_, make_vector(1, 1), _)).Times(3);
  auto mat_1 = mock.get(mock.get(cast_p(1), "", "u_normalMap"));
  auto mat_2 = mock.get(mock.get(cast_p(2), "", "u_normalMap"));
  EXPECT_THAT(mat_1.uniforms[0].texture, Eq(mat_2.uniforms[0].texture));
}