#include <gint/display.h>
#include <gint/keyboard.h>
#include <gint/std/string.h>
#include "engine.h"

#define CELL_X(x) (-2 + 10 * (x))
#define CELL_Y(y) (-3 + 10 * (y))

//---
//  Utilities
//---


/* Determine the cycle pattern for a certain door */
static char const *map_door_cycle(struct map const *map, int x, int y)
{
	int door = map->tiles[y * map->w + x];
	int cycle_id = -1;

	if(door >= TILE_VDOOR && door < TILE_VDOOR + 8)
		cycle_id = door - TILE_VDOOR;
	else if(door >= TILE_HDOOR && door < TILE_HDOOR + 8)
		cycle_id = door - TILE_HDOOR + 8;
	else
		return NULL;

	return map->door_cycle + map->door_cycle_index[cycle_id];
}

/* Check whether a cell of the map is walkable */
static bool map_walkable(struct game const *game, int x, int y)
{
	/* Refuse to walk on walls */
	int tile = game->map->tiles[y * game->map->w + x];
	if(tile == TILE_WALL) return false;

	/* Refuse to walk on closed doors */
	for(int t = 0; t < game->dynamic_tile_count; t++)
	{
		struct dynamic_tile const *dt = &game->dynamic_tiles[t];
		if(dt->x != x || dt->y != y) continue;

		char const *cycle = map_door_cycle(game->map, x, y);
		if(!dt->state2 && cycle[dt->state] == '#')
			return false;
	}

	return true;
}

//---
//  Map loading
//---

void engine_load(struct game *game, struct map const *map)
{
	game->map = map;
	game->time = 0;

	for(int p = 0; p < PLAYER_COUNT + 1; p++)
		game->players[p] = NULL;

	memset(&game->dynamic_tiles, 0,
		MAP_DYNAMIC_TILES * sizeof(struct dynamic_tile));

	/* Create dynamic tiles for suitable tiles in the map */
	int t = 0;

	for(int y = 0; y < map->h && t < MAP_DYNAMIC_TILES; y++)
	for(int x = 0; x < map->w && t < MAP_DYNAMIC_TILES; x++)
	{
		int tile = map->tiles[y*map->w + x];
		struct dynamic_tile *dt = &game->dynamic_tiles[t];

		dt->y = y;
		dt->x = x;
		dt->state = 0;

		int is_dynamic = 1;

		if(tile == TILE_START)
		{
			dt->idle = !anim_tile_start(&dt->anim, 1);
		}
		else if(tile == TILE_END)
		{
			dt->idle = !anim_tile_end(&dt->anim, 1);
		}
		else if(tile >= TILE_KEY && tile < TILE_KEY + 8)
		{
			/* TODO: Initial keys' dynamic tile information */
		}
		else if((tile >= TILE_VDOOR && tile < TILE_VDOOR + 8) ||
		        (tile >= TILE_HDOOR && tile < TILE_HDOOR + 8))
		{
			dt->anim.dir = (tile < TILE_HDOOR) ? DIR_UP : DIR_LEFT;
			char const *cycle = map_door_cycle(map, x, y);

			if(cycle[dt->state] == '#')
				dt->idle = !anim_door_closed(&dt->anim, 1);
			else
				dt->idle = !anim_door_open(&dt->anim, 1);

		}
		else is_dynamic = 0;

		t += is_dynamic;
	}

	game->dynamic_tile_count = t;
}

void engine_spawn(struct game *game)
{
	struct map const *map = game->map;
	int p = 0;

	for(int y = 0; y < map->h && game->players[p]; y++)
	for(int x = 0; x < map->w && game->players[p]; x++)
	{
		/* Try to spawn a player at (x,y) */
		if(map->tiles[y*map->w + x] == TILE_START)
		{
			struct player *player = game->players[p];

			player->y = y;
			player->x = x;
			player->dir = DIR_DOWN;
			player->anim.dir = DIR_DOWN;
			player->idle = !anim_player_idle(&player->anim, 1);

			p++;
		}
	}
}

bool engine_all_players_idle(struct game *game)
{
	for(int p = 0; game->players[p]; p++)
	{
		if(!game->players[p]->idle) return false;
	}
	return true;
}

bool engine_all_dynamic_tiles_idle(struct game *game)
{
	for(int t = 0; t < game->dynamic_tile_count; t++)
	{
		if(!game->dynamic_tiles[t].idle) return false;
	}
	return true;
}

bool engine_wins(struct game *game, struct player *player)
{
	/* First check that the player is participating in this game */
	bool found = false;
	for(int p = 0; game->players[p] && !found; p++)
	{
		if(game->players[p] == player) found = true;
	}
	if(!found) return false;

	int tile = game->map->tiles[player->y * game->map->w + player->x];
	return (tile == TILE_END);
}

//---
//  Animations
//---

void engine_tick(struct game *game, int delta_time)
{
	game->time += delta_time;

	/* Update the animations for every player */
	for(int p = 0; game->players[p]; p++)
	{
		struct player *player = game->players[p];

		player->anim.duration -= delta_time;
		if(player->anim.duration > 0) continue;

		/* Call the animation function to generate the next frame */
		player->idle = !player->anim.function(&player->anim, 0);
	}

	/* Update animations for dynamic tiles */
	for(int t = 0; t < game->dynamic_tile_count; t++)
	{
		struct dynamic_tile *dt = &game->dynamic_tiles[t];

		dt->anim.duration -= delta_time;
		if(dt->anim.duration > 0) continue;

		dt->idle = !dt->anim.function(&dt->anim, 0);
	}
}

//---
//  Rendering
//---

static void engine_draw_player(struct player const *player)
{
	dframe(CELL_X(player->x) - 1 + player->anim.dx,
	       CELL_Y(player->y) - 5 + player->anim.dy,
	       player->anim.img);
}

static void engine_draw_dynamic_tile(struct dynamic_tile const *dt)
{
	/* The -10 is hardcoded to suit the format of the tilesheet */
	dframe(CELL_X(dt->x) + dt->anim.dx,
	       CELL_Y(dt->y) + dt->anim.dy - 10,
	       dt->anim.img);
}

void engine_draw(struct game const *game)
{
	dclear(C_WHITE);
	dimage(0, 0, game->map->img);

	for(int t = 0; t < game->dynamic_tile_count; t++)
	{
		engine_draw_dynamic_tile(&game->dynamic_tiles[t]);
	}

	for(int p = 0; game->players[p]; p++)
	{
		engine_draw_player(game->players[p]);
	}
}

//---
//  Physics
//---

int engine_move(struct game *game, struct player *player, int dir)
{
	int dx = (dir == DIR_RIGHT) - (dir == DIR_LEFT);
	int dy = (dir == DIR_DOWN)  - (dir == DIR_UP);
	int olddir = player->dir;

	/* Don't move players that are already moving */
	if(!player->idle) return 0;

	/* Update the direction */
	player->dir = dir;
	player->anim.dir = dir;

	/* Only move the player if the destination is walkable */
	if(!map_walkable(game, player->x + dx, player->y + dy))
	{
		/* If not, set the new idle animation */
		if(dir != olddir)
		{
			player->idle = !anim_player_idle(&player->anim,1);
		}
		return 0;
	}

	player->x += dx;
	player->y += dy;

	/* Set the walking animation */
	player->idle = !anim_player_walking(&player->anim, 1);

	return 1;
}

void engine_finish_turn(struct game *game)
{
	/* TODO: Have players pick up keys and open corresponding doors */

	/* Update door cycles */
	for(int t = 0; t < game->dynamic_tile_count; t++)
	{
		struct dynamic_tile *dt = &game->dynamic_tiles[t];
		char const *cycle = map_door_cycle(game->map, dt->x, dt->y);
		if(!cycle) continue;

		/* Determine current open/closed status */
		int current_status = dt->state2 ? '.' : cycle[dt->state];

		/* Move to next cycle state */
		dt->state++;
		if(cycle[dt->state] == ' ' || cycle[dt->state] == 0)
			dt->state = 0;
		dt->state2 = 0;

		/* Determine next open/closed status (this might be different
		   from the cycle state if a player standing in the door
		   prevents if from closing) */
		int new_status = cycle[dt->state];

		for(int p = 0; game->players[p]; p++)
		{
			struct player *player = game->players[p];
			if(player->x == dt->x && player->y == dt->y)
			{
				new_status = '.';
				dt->state2 = 1;
			}
		}

		if(new_status == current_status) continue;

		/* Set animations when changing status */
		if(new_status == '#')
			dt->idle = !anim_door_closing(&dt->anim, 1);
		else if(new_status == '.')
			dt->idle = !anim_door_opening(&dt->anim, 1);
	}
}