// ----------------------------------------------------------------
// From Game Programming in C++ by Sanjay Madhav
// Copyright (C) 2017 Sanjay Madhav. All rights reserved.
// 
// Released under the BSD License
// See LICENSE in root directory for full details.
// ----------------------------------------------------------------

#include "Game.h"
#include <algorithm>
#include "Renderer.h"
#include "AudioSystem.h"
#include "Actor.h"
#include "SpriteComponent.h"
#include "MeshComponent.h"
#include "FPSActor.h"
#include "PlaneActor.h"
#include "AudioComponent.h"
#include "FollowActor.h"
#include "OrbitActor.h"
#include "SplineActor.h"

Game::Game()
:mRenderer(nullptr)
,mAudioSystem(nullptr)
,mIsRunning(true)
,mUpdatingActors(false)
{
	
}

bool Game::Initialize()
{
	if (SDL_Init(SDL_INIT_VIDEO|SDL_INIT_AUDIO) != 0)
	{
		SDL_Log("Unable to initialize SDL: %s", SDL_GetError());
		return false;
	}

	// Create the renderer
	mRenderer = new Renderer(this);
	if (!mRenderer->Initialize(1024.0f, 768.0f))
	{
		SDL_Log("Failed to initialize renderer");
		delete mRenderer;
		mRenderer = nullptr;
		return false;
	}

	// Create the audio system
	mAudioSystem = new AudioSystem(this);
	if (!mAudioSystem->Initialize())
	{
		SDL_Log("Failed to initialize audio system");
		mAudioSystem->Shutdown();
		delete mAudioSystem;
		mAudioSystem = nullptr;
		return false;
	}

	LoadData();

	mTicksCount = SDL_GetTicks();
	
	return true;
}

void Game::RunLoop()
{
	while (mIsRunning)
	{
		ProcessInput();
		UpdateGame();
		GenerateOutput();
	}
}

void Game::ProcessInput()
{
	SDL_Event event;
	while (SDL_PollEvent(&event))
	{
		switch (event.type)
		{
			case SDL_QUIT:
				mIsRunning = false;
				break;
			// This fires when a key's initially pressed
			case SDL_KEYDOWN:
				if (!event.key.repeat)
				{
					HandleKeyPress(event.key.keysym.sym);
				}
				break;
			case SDL_MOUSEBUTTONDOWN:
				HandleKeyPress(event.button.button);
				break;
			default:
				break;
		}
	}
	
	const Uint8* state = SDL_GetKeyboardState(NULL);
	if (state[SDL_SCANCODE_ESCAPE])
	{
		mIsRunning = false;
	}

	for (auto actor : mActors)
	{
		actor->ProcessInput(state);
	}
}

void Game::HandleKeyPress(int key)
{
	switch (key)
	{
	case '-':
	{
		// Reduce master volume
		float volume = mAudioSystem->GetBusVolume("bus:/");
		volume = Math::Max(0.0f, volume - 0.1f);
		mAudioSystem->SetBusVolume("bus:/", volume);
		break;
	}
	case '=':
	{
		// Increase master volume
		float volume = mAudioSystem->GetBusVolume("bus:/");
		volume = Math::Min(1.0f, volume + 0.1f);
		mAudioSystem->SetBusVolume("bus:/", volume);
		break;
	}
	case '1':
	case '2':
	case '3':
	case '4':
		ChangeCamera(key);
		break;
	case SDL_BUTTON_LEFT:
	{
		// Get start point (in center of screen on near plane)
		Vector3 screenPoint(0.0f, 0.0f, 0.0f);
		Vector3 start = mRenderer->Unproject(screenPoint);
		// Get end point (in center of screen, between near and far)
		screenPoint.z = 0.9f;
		Vector3 end = mRenderer->Unproject(screenPoint);
		// Set spheres to points
		mStartSphere->SetPosition(start);
		mEndSphere->SetPosition(end);
		break;
	}
	default:
		break;
	}
}

void Game::UpdateGame()
{
	// Compute delta time
	// Wait until 16ms has elapsed since last frame
	while (!SDL_TICKS_PASSED(SDL_GetTicks(), mTicksCount + 16))
		;

	float deltaTime = (SDL_GetTicks() - mTicksCount) / 1000.0f;
	if (deltaTime > 0.05f)
	{
		deltaTime = 0.05f;
	}
	mTicksCount = SDL_GetTicks();

	// Update all actors
	mUpdatingActors = true;
	for (auto actor : mActors)
	{
		actor->Update(deltaTime);
	}
	mUpdatingActors = false;

	// Move any pending actors to mActors
	for (auto pending : mPendingActors)
	{
		pending->ComputeWorldTransform();
		mActors.emplace_back(pending);
	}
	mPendingActors.clear();

	// Add any dead actors to a temp vector
	std::vector<Actor*> deadActors;
	for (auto actor : mActors)
	{
		if (actor->GetState() == Actor::EDead)
		{
			deadActors.emplace_back(actor);
		}
	}

	// Delete dead actors (which removes them from mActors)
	for (auto actor : deadActors)
	{
		delete actor;
	}

	// Update audio system
	mAudioSystem->Update(deltaTime);
}

void Game::GenerateOutput()
{
	mRenderer->Draw();
}

void Game::LoadData()
{
	// Create actors
	Actor* a = new Actor(this);
	a->SetPosition(Vector3(200.0f, 75.0f, 0.0f));
	a->SetScale(100.0f);
	Quaternion q(Vector3::UnitY, -Math::PiOver2);
	q = Quaternion::Concatenate(q, Quaternion(Vector3::UnitZ, Math::Pi + Math::Pi / 4.0f));
	a->SetRotation(q);
	MeshComponent* mc = new MeshComponent(a);
	mc->SetMesh(mRenderer->GetMesh("Assets/Cube.gpmesh"));

	a = new Actor(this);
	a->SetPosition(Vector3(200.0f, -75.0f, 0.0f));
	a->SetScale(3.0f);
	mc = new MeshComponent(a);
	mc->SetMesh(mRenderer->GetMesh("Assets/Sphere.gpmesh"));

	// Setup floor
	const float start = -1250.0f;
	const float size = 250.0f;
	for (int i = 0; i < 10; i++)
	{
		for (int j = 0; j < 10; j++)
		{
			a = new PlaneActor(this);
			a->SetPosition(Vector3(start + i * size, start + j * size, -100.0f));
		}
	}

	// Left/right walls
	q = Quaternion(Vector3::UnitX, Math::PiOver2);
	for (int i = 0; i < 10; i++)
	{
		a = new PlaneActor(this);
		a->SetPosition(Vector3(start + i * size, start - size, 0.0f));
		a->SetRotation(q);
		
		a = new PlaneActor(this);
		a->SetPosition(Vector3(start + i * size, -start + size, 0.0f));
		a->SetRotation(q);
	}

	q = Quaternion::Concatenate(q, Quaternion(Vector3::UnitZ, Math::PiOver2));
	// Forward/back walls
	for (int i = 0; i < 10; i++)
	{
		a = new PlaneActor(this);
		a->SetPosition(Vector3(start - size, start + i * size, 0.0f));
		a->SetRotation(q);

		a = new PlaneActor(this);
		a->SetPosition(Vector3(-start + size, start + i * size, 0.0f));
		a->SetRotation(q);
	}

	// Setup lights
	mRenderer->SetAmbientLight(Vector3(0.2f, 0.2f, 0.2f));
	DirectionalLight& dir = mRenderer->GetDirectionalLight();
	dir.mDirection = Vector3(0.0f, -0.707f, -0.707f);
	dir.mDiffuseColor = Vector3(0.78f, 0.88f, 1.0f);
	dir.mSpecColor = Vector3(0.8f, 0.8f, 0.8f);

	// UI elements
	a = new Actor(this);
	a->SetPosition(Vector3(-350.0f, -350.0f, 0.0f));
	SpriteComponent* sc = new SpriteComponent(a);
	sc->SetTexture(mRenderer->GetTexture("Assets/HealthBar.png"));

	a = new Actor(this);
	a->SetPosition(Vector3(-390.0f, 275.0f, 0.0f));
	a->SetScale(0.75f);
	sc = new SpriteComponent(a);
	sc->SetTexture(mRenderer->GetTexture("Assets/Radar.png"));

	a = new Actor(this);
	a->SetScale(2.0f);
	mCrosshair = new SpriteComponent(a);
	mCrosshair->SetTexture(mRenderer->GetTexture("Assets/Crosshair.png"));

	// Start music
	mMusicEvent = mAudioSystem->PlayEvent("event:/Music");

	// Enable relative mouse mode for camera look
	SDL_SetRelativeMouseMode(SDL_TRUE);
	// Make an initial call to get relative to clear out
	SDL_GetRelativeMouseState(nullptr, nullptr);

	// Different camera actors
	mFPSActor = new FPSActor(this);
	mFollowActor = new FollowActor(this);
	mOrbitActor = new OrbitActor(this);
	mSplineActor = new SplineActor(this);

	ChangeCamera('1');

	// Spheres for demonstrating unprojection
	mStartSphere = new Actor(this);
	mStartSphere->SetPosition(Vector3(10000.0f, 0.0f, 0.0f));
	mStartSphere->SetScale(0.25f);
	mc = new MeshComponent(mStartSphere);
	mc->SetMesh(mRenderer->GetMesh("Assets/Sphere.gpmesh"));
	mEndSphere = new Actor(this);
	mEndSphere->SetPosition(Vector3(10000.0f, 0.0f, 0.0f));
	mEndSphere->SetScale(0.25f);
	mc = new MeshComponent(mEndSphere);
	mc->SetMesh(mRenderer->GetMesh("Assets/Sphere.gpmesh"));
	mc->SetTextureIndex(1);
}

void Game::UnloadData()
{
	// Delete actors
	// Because ~Actor calls RemoveActor, have to use a different style loop
	while (!mActors.empty())
	{
		delete mActors.back();
	}

	if (mRenderer)
	{
		mRenderer->UnloadData();
	}
}

void Game::Shutdown()
{
	UnloadData();
	if (mRenderer)
	{
		mRenderer->Shutdown();
	}
	if (mAudioSystem)
	{
		mAudioSystem->Shutdown();
	}
	SDL_Quit();
}

void Game::AddActor(Actor* actor)
{
	// If we're updating actors, need to add to pending
	if (mUpdatingActors)
	{
		mPendingActors.emplace_back(actor);
	}
	else
	{
		mActors.emplace_back(actor);
	}
}

void Game::RemoveActor(Actor* actor)
{
	// Is it in pending actors?
	auto iter = std::find(mPendingActors.begin(), mPendingActors.end(), actor);
	if (iter != mPendingActors.end())
	{
		// Swap to end of vector and pop off (avoid erase copies)
		std::iter_swap(iter, mPendingActors.end() - 1);
		mPendingActors.pop_back();
	}

	// Is it in actors?
	iter = std::find(mActors.begin(), mActors.end(), actor);
	if (iter != mActors.end())
	{
		// Swap to end of vector and pop off (avoid erase copies)
		std::iter_swap(iter, mActors.end() - 1);
		mActors.pop_back();
	}
}

void Game::ChangeCamera(int mode)
{
	// Disable everything
	mFPSActor->SetState(Actor::EPaused);
	mFPSActor->SetVisible(false);
	mCrosshair->SetVisible(false);
	mFollowActor->SetState(Actor::EPaused);
	mFollowActor->SetVisible(false);
	mOrbitActor->SetState(Actor::EPaused);
	mOrbitActor->SetVisible(false);
	mSplineActor->SetState(Actor::EPaused);

	// Enable the camera specified by the mode
	switch (mode)
	{
	case '1':
	default:
		mFPSActor->SetState(Actor::EActive);
		mFPSActor->SetVisible(true);
		mCrosshair->SetVisible(true);
		break;
	case '2':
		mFollowActor->SetState(Actor::EActive);
		mFollowActor->SetVisible(true);
		break;
	case '3':
		mOrbitActor->SetState(Actor::EActive);
		mOrbitActor->SetVisible(true);
		break;
	case '4':
		mSplineActor->SetState(Actor::EActive);
		mSplineActor->RestartSpline();
		break;
	}
}