#define OLC_PGE_APPLICATION
#include "olcPixelGameEngine.h"

struct Rect{
	int x,y,w,h;
};

class Enemy{
	olc::vf2d pos;
	Rect*sprite;
	int health;
public:
	Enemy(olc::vi2d pos,Rect*sprite,int health=1)
		:pos(pos),sprite(sprite),health(health){};
	olc::vf2d GetPos(){
		return pos;	
	}
	olc::vi2d GetSprPos(){
		return {sprite->x,sprite->y};	
	}
	olc::vi2d GetSprSize(){
		return {sprite->w,sprite->h};	
	}
	void Hurt(int damage=1){
		health-=damage;
	}
	bool IsAlive(){
		return health>0;
	}
	void Move(olc::vi2d moveAmt){
		pos+=moveAmt;
	}
	olc::Pixel GetColor(){
		if(health>1){
			return {255,96,96};
		} else {
			return olc::GREEN;
		}
	}
};

class Player{
	olc::vf2d pos;
	Rect*sprite;
	float lastShootTime=0;
public:
	Player(olc::vi2d pos,Rect*sprite)
		:pos(pos),sprite(sprite){}
	olc::vf2d GetPos(){
		return pos;
	}
	olc::vi2d GetSprPos(){
		return {sprite->x,sprite->y};	
	}
	olc::vi2d GetSprSize(){
		return {sprite->w,sprite->h};	
	}
	void Update(float fElapsedTime){
		lastShootTime=std::max(lastShootTime-fElapsedTime,0.f);
	}
	bool CanShoot(){
		return lastShootTime==0;
	}
	void OnShoot(){
		lastShootTime=0.5;
	}
	void Move(olc::vf2d moveAmt){
		pos+=moveAmt;
	}
};

class Bullet{
	olc::vf2d pos;
	bool alive=true;
public:
	Bullet(olc::vi2d pos)
		:pos(pos){}
	olc::vf2d GetPos(){
		return pos;
	}
	void Update(float fElapsedTime){
		pos+={0,-72*fElapsedTime};
	}
	bool CollidesWith(Enemy&enemy){
		float dist2=pow(enemy.GetPos().x+enemy.GetSprSize().x-pos.x,2)+pow(enemy.GetPos().y+enemy.GetSprSize().y-pos.y,2);
		return dist2<64;
	}
	void KillBullet(){
		alive=false;
	}
	bool IsAlive(){
		return alive||pos.y<0;
	}
};

// Override base class with your custom functionality
class ShooterExample : public olc::PixelGameEngine
{
public:
	ShooterExample()
	{
		// Name your application
		sAppName = "Shooter Example";
	}

public:
	olc::Renderable spriteSheet;
	Rect enemyA={5,21,	11,9};
	Rect enemyB={19,22,	12,6};
	Rect enemyC={34,20,	11,8};
	Rect ship={35,6,	11,7};

	std::vector<Enemy>enemies;
	std::vector<Bullet>bullets;

	Player player{{ScreenWidth()/2,ScreenHeight()-36},&ship};
	int alienShift=0;
	bool movingRight=true;
	float lastShiftTime=0;
	
	bool OnUserCreate() override
	{
		spriteSheet.Load("8-bit Aliens.png");

		olc::vf2d alienOffset={24,38};
		for (int y=0;y<4;y++){
			for (int x=0;x<12;x++){
				switch(rand()%3){
					case 0:{
						Enemy enemy{alienOffset+olc::vi2d{x*16,y*12},&enemyA};
						enemies.push_back(enemy);
					}break;
					case 1:{
						Enemy enemy{alienOffset+olc::vi2d{x*16,y*12},&enemyB};
						enemies.push_back(enemy);
					}break;
					case 2:{
						Enemy enemy{alienOffset+olc::vi2d{x*16,y*12},&enemyC,2};
						enemies.push_back(enemy);
					}break;
				}
			}
		}
		return true;
	}

	bool OnUserUpdate(float fElapsedTime) override
	{
		//Update Game Objects
		player.Update(fElapsedTime);

		for(Bullet&b:bullets){
			b.Update(fElapsedTime);
		}

		lastShiftTime+=fElapsedTime;
		if(lastShiftTime>0.8){
			lastShiftTime-=0.8;
			if(abs(alienShift)>=3){
				alienShift+=movingRight?-1:1;
				movingRight=!movingRight;
				for(Enemy&e:enemies){
					e.Move({0,12});
				}
			} else
			if(movingRight){
				alienShift++;
				for(Enemy&e:enemies){
					e.Move({12,0});
				}
			} else {
				alienShift--;
				for(Enemy&e:enemies){
					e.Move({-12,0});
				}
			}
		}

		if(GetKey(olc::SPACE).bHeld){
			if(player.CanShoot()){
				player.OnShoot();
				bullets.push_back({player.GetPos()+player.GetSprSize()});
			}
		}
		if(GetKey(olc::LEFT).bHeld){
			player.Move({-48*fElapsedTime,0});
		}
		if(GetKey(olc::RIGHT).bHeld){
			player.Move({48*fElapsedTime,0});
		}

		// Called once per frame, draws random coloured pixels
		Clear(olc::BLACK);
		for(Enemy&e:enemies){
			for(Bullet&b:bullets){
				if(!b.IsAlive())continue;
				if(b.CollidesWith(e)){
					e.Hurt();
					b.KillBullet();
				}
				DrawLineDecal(b.GetPos(),b.GetPos()+olc::vi2d{0,-4},olc::WHITE);
			}
			DrawPartialDecal(e.GetPos()+e.GetSprSize()/2,e.GetSprSize(),spriteSheet.Decal(),e.GetSprPos(),e.GetSprSize(),e.GetColor());
		}

		DrawPartialDecal(player.GetPos()+player.GetSprSize()/2,player.GetSprSize(),spriteSheet.Decal(),player.GetSprPos(),player.GetSprSize());

		enemies.erase(std::remove_if(enemies.begin(),enemies.end(),[](Enemy&e){return !e.IsAlive();}),enemies.end());
		bullets.erase(std::remove_if(bullets.begin(),bullets.end(),[](Bullet&b){return !b.IsAlive();}),bullets.end());
		return true;
	}
};

int main()
{
	ShooterExample demo;
	if (demo.Construct(256, 240, 4, 4))
		demo.Start();
	return 0;
}