/*
 * Copyright (C) 2021  P. J. McDermott
 *
 * This file is part of Dodge Balls
 *
 * Dodge Balls is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Dodge Balls is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Dodge Balls.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <math.h>
#include <stdlib.h>
#include "ball.h"
#include "collision.h"
#include "map.h"
#include "tileset.h"
#include "output.h"

struct db_ball {
	int                cx;
	int                cy;
	double             x;
	double             y;
	int                r;
	double             a;
	int                d;
	int                sr;
	double             s;
	struct db_tileset *tilesets;
	int                gid;
	struct db_map     *map;
	struct db_ball    *next;
};

struct db_ball *
db_ball_new(int x, int y, int r, int a, int d, int sr, double s,
		struct db_tileset *tilesets, int gid, struct db_map *map,
		struct db_ball *prev)
{
	struct db_ball *ball;

	ball = calloc(1, sizeof(*ball));
	if (ball == NULL) {
		db_err("Failed to allocate memory");
		return NULL;
	}

	db_dbg("Ball at (%d,%d)", x, y);
	if (sr == 0) {
		ball->x  = x;
		ball->y  = y;
	} else {
		ball->cx = x;
		ball->cy = y;
		ball->x  = x + cos(a * (M_PI / 180)) * sr;
		ball->y  = y + sin(a * (M_PI / 180)) * sr;
	}
	ball->r        = r;
	ball->a        = a;
	ball->d        = d;
	ball->sr       = sr;
	ball->s        = s;
	ball->tilesets = tilesets;
	ball->gid      = gid;
	ball->map      = map;

	if (prev != NULL) {
		prev->next = ball;
	}

	return ball;
}

void
db_balls_move(struct db_ball *ball)
{
	if (ball->sr == 0) {
		ball->x += cos(ball->a * (M_PI / 180)) * ball->s;
		ball->y += sin(ball->a * (M_PI / 180)) * ball->s;
	} else {
		ball->a  = fmod(ball->a + ball->d * ball->s, 360);
		ball->x  = ball->cx + cos(ball->a * (M_PI / 180)) * ball->sr;
		ball->y  = ball->cy + sin(ball->a * (M_PI / 180)) * ball->sr;
		db_dbg("Spinning ball angle %f (speed %f, direction %d)",
				ball->a, ball->s, ball->d);
	}

	if (ball->next != NULL) {
		db_balls_move(ball->next);
	}
}

static void
_db_ball_bounce(struct db_ball *ball, double col_x, double col_y)
{
	double col_a;

	col_a = atan2(col_y - ball->y, col_x - ball->x) * 180 / M_PI;
	ball->a = fmod(2 * col_a - ball->a - 180, 360);
}

void
db_balls_collisions(struct db_ball *ball)
{
	struct db_ball     *other;
	double              col_x;
	double              col_y;
	struct db_map_line *line;
	double              prev_col_x;
	double              prev_col_y;
	int                 line_x1;
	int                 line_y1;
	int                 line_x2;
	int                 line_y2;

	/* Spinning balls shouldn't collide with any other balls */
	if (ball->sr == 0) {
		for (other = ball->next; other != NULL; other = other->next) {
			if (other->sr == 0 && db_col_pt_cir_cir(
						 ball->x,  ball->y,  ball->r,
						other->x, other->y, other->r,
						&col_x, &col_y)) {
				_db_ball_bounce(ball , col_x, col_y);
				_db_ball_bounce(other, col_x, col_y);
			}
		}
	}

	/* Spinning balls shouldn't bounce off walls */
	if (ball->sr == 0) {
		prev_col_x = prev_col_y = -1;
		for (line = db_map_get_lines(ball->map); line != NULL;
				line = db_map_line_get_next(line)) {
			db_map_line_get_coords(line, &line_x1, &line_y1,
					&line_x2, &line_y2);
			col_x = col_y = 0;  /* Shut up GCC */
			if (db_col_cir_line(ball->x, ball->y, ball->r,
						line_x1, line_y1,
						line_x2, line_y2,
						&col_x, &col_y)){
				if (col_x == prev_col_x || col_y == prev_col_y){
					continue;
				}
				_db_ball_bounce(ball, col_x, col_y);
				prev_col_x = col_x;
				prev_col_y = col_y;
			}
		}
	}

	if (ball->next != NULL) {
		db_balls_collisions(ball->next);
	}
}

int
db_balls_player_collisions(struct db_ball *ball,
		int player_x, int player_y, int player_r)
{
	if (db_col_cir_cir(ball->x, ball->y, ball->r,
				player_x, player_y, player_r)) {
		return 1;
	}

	if (ball->next != NULL) {
		return db_balls_player_collisions(ball->next,
				player_x, player_y, player_r);
	} else {
		return 0;
	}
}

void
db_balls_render(struct db_ball *ball, SDL_Renderer *renderer)
{
	SDL_Rect dstrect;

	dstrect.x = ball->x - ball->r;
	dstrect.y = ball->y - ball->r;
	dstrect.w = ball->r * 2;
	dstrect.h = ball->r * 2;
	db_dbg("Rendering ball (%dx%d) at (%d,%d)",
			dstrect.w, dstrect.h, dstrect.x, dstrect.y);
	db_tile_render(ball->tilesets, renderer, ball->gid, &dstrect);

	if (ball->next != NULL) {
		db_balls_render(ball->next, renderer);
	}
}