#include <SDL2/SDL.h>

#include <assert.h>
#include <stdbool.h>
#include <math.h>

#include "game.h"

#define SPEED  0.00006
#define ROTATE 0.00004
#define BULL_SPEED 0.008

Player g_player[MAX_PLAYERS];
Bullet g_bullet[MAX_BULLETS];

void g_player_set(unsigned int id, bool live, float x, float y, float r, float vx, float vy, float vr) {
	assert(id < MAX_PLAYERS);
	g_player[id] = (Player) {
		.updated = true,
		.live    = live,
		.x       = x,
		.y       = y,
		.r       = r,
		.vx      = vx,
		.vy      = vy,
		.vr      = vr,
	};
}

void g_bullet_set(unsigned int id, unsigned int owner, bool live, float x, float y, float vx, float vy, int tick) {
	assert(id < MAX_BULLETS);
	assert(owner < MAX_PLAYERS);
	g_bullet[id] = (Bullet) {
		.live  = live,
		.owner = owner,
		.x     = x,
		.y     = y,
		.vx    = vx,
		.vy    = vy,
		.tick  = tick,
	};
}

static int freebullet() {
	for(int i = 0; i < MAX_BULLETS; i++)
		if(!g_bullet[i].live)
			return i;
	return -1;
}

static void moveplayer(int id, float speed) {
	g_player[id].vx += speed * cos(g_player[id].r * 2 * M_PI);
	g_player[id].vy += speed * sin(g_player[id].r * 2 * M_PI);
}

static void roteplayer(int id, float speed) {
	g_player[id].vr += speed;
}

static void fireplayer(int id) {
	int j = freebullet();
	if(j < 0)
		return;

	float vx = BULL_SPEED * cos(g_player[id].r * 2 * M_PI);
	float vy = BULL_SPEED * sin(g_player[id].r * 2 * M_PI);
	g_bullet_set(j, id, true, g_player[id].x, g_player[id].y, vx, vy, 0);
}

static void checkspacebound(float * a) {
	float x = *a;
	if(x < -1)
		x = fabs(x);
	else if(x > 1)
		x = -x;
	*a = x;
}

static bool collide(float x1, float y1, float r1, float x2, float y2, float r2) {
	float l = sqrtf(powf(x1 - x2, 2) + powf(y1 - y2, 2));
	return ((l - r1 - r2) <= 0);
}

void g_player_does(unsigned int id, DoesCode code) {
	assert(id < MAX_PLAYERS);
	g_player[id].updated = true;
	switch(code) {
	case DOES_UP:    moveplayer(id, SPEED); break;
	case DOES_DOWN:  moveplayer(id, -SPEED); break;
	case DOES_LEFT:  roteplayer(id, -ROTATE); break;
	case DOES_RIGHT: roteplayer(id, ROTATE); break;
	case DOES_FIRE:  fireplayer(id); break;
	}
}

void g_update() {
	for(int i = 0; i < MAX_PLAYERS; i++) {
		if(g_player[i].live) {
			g_player[i].updated = true;
			g_player[i].x += g_player[i].vx;
			g_player[i].y += g_player[i].vy;
			g_player[i].r += g_player[i].vr;
			checkspacebound(&g_player[i].x);
			checkspacebound(&g_player[i].y);
		}
	}

	for(int i = 0; i < MAX_BULLETS; i++) {
		if(g_bullet[i].live) {
			g_bullet[i].updated = true;
			g_bullet[i].tick += 1;
			g_bullet[i].x += g_bullet[i].vx;
			g_bullet[i].y += g_bullet[i].vy;

			checkspacebound(&g_bullet[i].x);
			checkspacebound(&g_bullet[i].y);

			for(int j = 0; j < MAX_PLAYERS; j++)
				if(g_player[j].live)
					if(collide(g_bullet[i].x, g_bullet[i].y, 0.0001, g_player[j].x, g_player[j].y, PLAYER_SIZE))
						if(j != g_bullet[i].owner)
							g_player[j].live = false;

			if(g_bullet[i].tick > BULLET_TIME)
				g_bullet[i].live = false;
		}
	}
}