/*
 * Copyright (C) 2013  Patrick "P. J." McDermott
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this program.  If not, see
 * <http://www.gnu.org/licenses/>.
 */

#include <SDL.h>
#include "area.h"
#include "viewport.h"
#include "resources/map.h"
#include "resources/tileset.h"
#include "logging.h"

static void init_map_layers(struct area *);
static void blit_map_layers(struct area *);
static void blit_map_layer(struct area *, enum map_layer, enum area_layer);

struct area *
area_new(struct map *map, SDL_Palette *pal)
{
	struct area *a;

	if (map == NULL) {
		return NULL;
	}

	a = malloc(sizeof(*a));
	if (a == NULL) {
		return NULL;
	}

	a->map = map;
	init_map_layers(a);
	set_area_palette(a, pal);
	blit_map_layers(a);

	return a;
}

void
set_area_palette(struct area *area, SDL_Palette *pal)
{
	enum area_layer l;

	for (l = 0; l < AREA_LAYERS_MAX; ++l) {
		SDL_SetPalette(area->map_layers[l], SDL_LOGPAL,
				pal->colors, 0, pal->ncolors);
	}
}

static void
init_map_layers(struct area *area)
{
	SDL_Rect dstrect;
	enum area_layer l;

	dstrect.x = 0;
	dstrect.y = 0;
	dstrect.w = area->map->width * area->map->tilewidth;
	dstrect.h = area->map->height * area->map->tileheight;

	for (l = 0; l < AREA_LAYERS_MAX; ++l) {
		area->map_layers[l] = SDL_CreateRGBSurface(
				SDL_HWSURFACE | SDL_SRCCOLORKEY,
				area->map->width * area->map->tilewidth,
				area->map->height * area->map->tileheight,
				8, 0x00, 0x00, 0x00, 0x00);
		SDL_FillRect(area->map_layers[l], &dstrect,
				SDL_MapRGB(area->map_layers[l]->format,
					0xFC, 0x00, 0xFF));
		SDL_SetColorKey(area->map_layers[l], SDL_SRCCOLORKEY,
				SDL_MapRGB(area->map_layers[l]->format,
					0xFC, 0x00, 0xFF));
	}
}

static void
blit_map_layers(struct area *area)
{
	blit_map_layer(area, MAP_LAYER_GROUND, AREA_LAYER_BOT);
	blit_map_layer(area, MAP_LAYER_OBJ_LOW, AREA_LAYER_BOT);
	blit_map_layer(area, MAP_LAYER_OBJ_MID, AREA_LAYER_MID);
	blit_map_layer(area, MAP_LAYER_OBJ_HIGH, AREA_LAYER_TOP);
}

static void
blit_map_layer(struct area *area, enum map_layer map_layer,
		enum area_layer area_layer)
{
	int i;
	Uint32 gid;
	int tile_found;
	struct map_tileset *mts;
	Uint32 mts_lastgid;
	SDL_Rect tilerect, layerrect;

	for (i = 0; i < area->map->width * area->map->height; ++i) {
		gid = area->map->layers[map_layer].tiles[i];
		if (gid == 0) {
			continue;
		}
		tile_found = 0;
		for (mts = area->map->tilesets_head;
				mts != NULL; mts = mts->next) {
			mts_lastgid = mts->firstgid +
				mts->tileset->width * mts->tileset->height;
			if (gid >= mts->firstgid && gid < mts_lastgid) {
				gid -= mts->firstgid;
				tilerect.x = gid % mts->tileset->width;
				tilerect.y = gid / mts->tileset->width;
				tilerect.w = mts->tileset->tilewidth;
				tilerect.h = mts->tileset->tileheight;
				tilerect.x *= tilerect.w;
				tilerect.y *= tilerect.h;
				layerrect.x = i % area->map->width;
				layerrect.y = i / area->map->width;
				layerrect.w = mts->tileset->tilewidth;
				layerrect.h = mts->tileset->tileheight;
				layerrect.x *= layerrect.w;
				layerrect.y *= layerrect.h;
#ifdef DEBUG_RENDER
				debug("Blitting %dx%d tile at (%d,%d) "
						"onto layer at (%d,%d)...",
						tilerect.w, tilerect.h,
						tilerect.x, tilerect.y,
						layerrect.x, layerrect.y);
#endif
				SDL_BlitSurface(mts->tileset->image->image,
						&tilerect,
						area->map_layers[area_layer],
						&layerrect);
				tile_found = 1;
				break;
			}
		}
		if (!tile_found) {
			warn("Tile with gid 0x%8.8x not found", gid);
		}
	}
}

void
render_area_to_viewport(struct area *area, struct viewport *vp)
{
	SDL_Rect srcrect;
	SDL_Rect dstrect;

	if (area == NULL || vp == NULL) {
		return;
	}

	srcrect.x = vp->x;
	srcrect.y = vp->y;
	srcrect.w = vp->w;
	srcrect.h = vp->h;
	dstrect.x = 0;
	dstrect.y = 0;
	dstrect.w = vp->w;
	dstrect.h = vp->h;

	render_area_to_surface(area, &srcrect, vp->screen, &dstrect);
}

void
render_area_to_surface(struct area *area, SDL_Rect *arearect,
		SDL_Surface *surface, SDL_Rect *surfacerect)
{
	SDL_Rect srcrect, dstrect;
	/* For demo */
	SDL_Rect tmprect;

	if (area == NULL || arearect == NULL) {
		return;
	}
	if (surface == NULL || surfacerect == NULL) {
		return;
	}

	memcpy(&srcrect, arearect, sizeof(srcrect));
	memcpy(&dstrect, surfacerect, sizeof(dstrect));

	/* Fast fill with black to avoid artifacts in off-map pixels. */
	/* NB: This is gray, at least temporarily. */
	SDL_FillRect(surface, &dstrect,
			SDL_MapRGB(surface->format, 0, 0, 0));

	/* For demo */
	tmprect.x = dstrect.x + 160 -  8;
	tmprect.y = dstrect.y + 120 - 12;
	tmprect.w = 16;
	tmprect.h = 20;

	/* Avoid fun glitches due to negative coordinates in source
	 * rectangles. */
	if (srcrect.x < 0) {
		srcrect.x = 0;
		dstrect.x = surfacerect->x - arearect->x;
	}
	if (srcrect.y < 0) {
		srcrect.y = 0;
		dstrect.y = surfacerect->y - arearect->y;
	}

#ifdef DEBUG_RENDER
	debug("Rendering %dx%d area rect at (%d,%d) "
			"onto %dx%d surface rect at (%d,%d)...",
			srcrect.w, srcrect.h, srcrect.x, srcrect.y,
			dstrect.w, dstrect.h, dstrect.x, dstrect.y);
#endif

	/* Blit bottom layer. */
	SDL_BlitSurface(area->map_layers[AREA_LAYER_BOT], &srcrect,
			surface, &dstrect);
/*	return;*/

	/* TODO: Blit low sprites. */

	/* For demo */
	SDL_FillRect(surface, &tmprect,
			SDL_MapRGB(surface->format, 255, 0, 255));

	/* Blit middle layer. */
	SDL_BlitSurface(area->map_layers[AREA_LAYER_MID], &srcrect,
			surface, &dstrect);

	/* TODO: Blit high sprites. */

	/* Blit top layer. */
	SDL_BlitSurface(area->map_layers[AREA_LAYER_TOP], &srcrect,
			surface, &dstrect);
}