/* Copyright (C) 2019  C. McEnroe <june@causal.agency>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <errno.h>
#include <stdlib.h>
#include <string.h>

#include "cards.h"

static SDL_Surface *
dibSurface(SDL_RWops *rw, Uint32 offset, Uint32 length) {
	Uint32 bitmapLength = 0x0E + length;

	Uint8 *buffer = malloc(bitmapLength);
	if (!buffer) {
		SDL_SetError("malloc error: %s", strerror(errno));
		return NULL;
	}

	SDL_RWops *bitmap = SDL_RWFromMem(buffer, bitmapLength);
	if (!bitmap) {
		free(buffer);
		return NULL;
	}

	if (SDL_RWseek(rw, offset, RW_SEEK_SET) < 0) goto fail;
	Uint32 dibHeaderLength = SDL_ReadLE32(rw);
	Uint32 bitmapDataOffset = 0x0E + dibHeaderLength;

	if (dibHeaderLength == 0x0C) {
		if (SDL_RWseek(rw, 0x06, RW_SEEK_CUR) < 0) goto fail;
		Uint16 bitsPerPixel = SDL_ReadLE16(rw);
		bitmapDataOffset += 3 * (1 << bitsPerPixel);

	} else if (dibHeaderLength == 0x28) {
		if (SDL_RWseek(rw, 0x0A, RW_SEEK_CUR) < 0) goto fail;
		Uint16 bitsPerPixel = SDL_ReadLE16(rw);
		if (SDL_RWseek(rw, 0x10, RW_SEEK_CUR) < 0) goto fail;
		Uint32 paletteLength = SDL_ReadLE32(rw);

		if (!paletteLength) paletteLength = 1 << bitsPerPixel;
		bitmapDataOffset += 4 * paletteLength;

	} else {
		SDL_SetError("unrecognized DIB header length %u", dibHeaderLength);
		goto fail;
	}

	SDL_WriteU8(bitmap, 'B');
	SDL_WriteU8(bitmap, 'M');
	SDL_WriteLE32(bitmap, bitmapLength);
	SDL_WriteLE16(bitmap, 0); // reserved
	SDL_WriteLE16(bitmap, 0); // reserved
	SDL_WriteLE32(bitmap, bitmapDataOffset);

	if (SDL_RWseek(rw, offset, RW_SEEK_SET) < 0) goto fail;
	if (SDL_RWread(rw, &buffer[SDL_RWtell(bitmap)], length, 1) < 1) goto fail;

	SDL_RWseek(bitmap, 0, RW_SEEK_SET);
	SDL_Surface *surface = SDL_LoadBMP_RW(bitmap, 1);
	free(buffer);
	return surface;

fail:
	SDL_RWclose(bitmap);
	free(buffer);
	return NULL;
}

static int setColorKey(struct Cards *cards) {
	int i = Cards_Empty;
	if (SDL_SetColorKey(cards->surfaces[i], SDL_TRUE, 1) < 0) return -1;
	for (i = Cards_X; i <= Cards_O; ++i) {
		if (SDL_SetColorKey(cards->surfaces[i], SDL_TRUE, 12) < 0) return -1;
	}
	return 0;
}

static int setAlphaCorners(struct Cards *cards) {
	SDL_Surface *alpha = NULL;
	for (int i = 0; i < Cards_Count; ++i) {
		if (!cards->surfaces[i]) continue;

		alpha = SDL_ConvertSurfaceFormat(
			cards->surfaces[i], SDL_PIXELFORMAT_RGBA32, 0
		);
		if (!alpha) return -1;

		if (SDL_SetSurfaceBlendMode(alpha, SDL_BLENDMODE_BLEND) < 0) goto fail;

		SDL_Rect rects[8] = {
			{ 0, 0, 2, 1 },
			{ 0, 1, 1, 1 },
			{ Cards_Width - 2, 0, 2, 1 },
			{ Cards_Width - 1, 1, 1, 1 },
			{ 0, Cards_Height - 1, 2, 1 },
			{ 0, Cards_Height - 2, 1, 1 },
			{ Cards_Width - 2, Cards_Height - 1, 2, 1 },
			{ Cards_Width - 1, Cards_Height - 2, 1, 1 },
		};
		Uint32 trans = SDL_MapRGBA(alpha->format, 0x00, 0x00, 0x00, 0x00);
		if (SDL_FillRects(alpha, rects, 8, trans) < 0) goto fail;

		SDL_FreeSurface(cards->surfaces[i]);
		cards->surfaces[i] = alpha;
	}
	return 0;

fail:
	SDL_FreeSurface(alpha);
	return -1;
}

static int setBlackBorders(struct Cards *cards) {
	for (int i = Cards_Diamond + Cards_A; i <= Cards_Heart + Cards_K; ++i) {
		if (!cards->surfaces[i]) continue;
		SDL_Rect rects[8] = {
			{ 2, 0, Cards_Width - 4, 1 },
			{ 2, Cards_Height - 1, Cards_Width - 4, 1 },
			{ 0, 2, 1, Cards_Height - 4 },
			{ Cards_Width - 1, 2, 1, Cards_Height - 4 },
			{ 1, 1, 1, 1 },
			{ Cards_Width - 2, 1, 1, 1 },
			{ 1, Cards_Height - 2, 1, 1 },
			{ Cards_Width - 2, Cards_Height - 2, 1, 1 },
		};
		Uint32 black = SDL_MapRGB(cards->surfaces[i]->format, 0x00, 0x00, 0x00);
		if (SDL_FillRects(cards->surfaces[i], rects, 8, black) < 0) return -1;
	}
	return 0;
}

struct Cards *Cards_Load(SDL_RWops *rw, enum Cards_Flags flags) {
	struct Cards *cards = calloc(1, sizeof(*cards));
	if (!cards) {
		SDL_SetError("calloc error: %s", strerror(errno));
		return NULL;
	}

	if (SDL_RWseek(rw, 0, RW_SEEK_SET) < 0) goto fail;
	if (SDL_ReadU8(rw) != 'M' || SDL_ReadU8(rw) != 'Z') {
		SDL_SetError("invalid MZ signature");
		goto fail;
	}

	if (SDL_RWseek(rw, 0x3C, RW_SEEK_SET) < 0) goto fail;
	Uint16 neOffset = SDL_ReadLE16(rw);

	if (SDL_RWseek(rw, neOffset, RW_SEEK_SET) < 0) goto fail;
	if (SDL_ReadU8(rw) != 'N' || SDL_ReadU8(rw) != 'E') {
		SDL_SetError("invalid NE signature");
		goto fail;
	}

	if (SDL_RWseek(rw, neOffset + 0x24, RW_SEEK_SET) < 0) goto fail;
	Uint16 resourceTableOffset = neOffset + SDL_ReadLE16(rw);

	if (SDL_RWseek(rw, resourceTableOffset, RW_SEEK_SET) < 0) goto fail;
	Uint16 alignmentShift = SDL_ReadLE16(rw);

	Uint16 resourceCount;
	for (;;) {
		Uint16 typeID = SDL_ReadLE16(rw);
		resourceCount = SDL_ReadLE16(rw);
		SDL_ReadLE32(rw); // reserved

		if (!typeID) {
			SDL_SetError("no bitmap resources");
			goto fail;
		}
		if (typeID == 0x8002) break;

		if (SDL_RWseek(rw, 0x0C * resourceCount, RW_SEEK_CUR) < 0) goto fail;
	}

	for (Uint16 i = 0; i < resourceCount; ++i) {
		Uint16 offset = SDL_ReadLE16(rw);
		Uint16 length = SDL_ReadLE16(rw);
		SDL_ReadLE16(rw); // flags
		Uint16 id = SDL_ReadLE16(rw);
		SDL_ReadLE32(rw); // reserved

		id &= 0x7FFF;
		if (id >= Cards_Count) continue;

		Sint64 next = SDL_RWtell(rw);
		if (next < 0) goto fail;

		cards->surfaces[id] = dibSurface(
			rw,
			(Uint32)offset << alignmentShift,
			(Uint32)length << alignmentShift
		);
		if (!cards->surfaces[id]) goto fail;

		if (SDL_RWseek(rw, next, RW_SEEK_SET) < 0) goto fail;
	}

	for (int i = Cards_Club + Cards_A; i <= Cards_Spade + Cards_K; ++i) {
		if (cards->surfaces[i]) continue;
		SDL_SetError("missing resource %d", i);
		goto fail;
	}
	for (int i = Cards_Empty; i <= Cards_Back12; ++i) {
		if (cards->surfaces[i]) continue;
		SDL_SetError("missing resource %d", i);
		goto fail;
	}
	for (int i = Cards_X; i <= Cards_O; ++i) {
		if (cards->surfaces[i]) continue;
		SDL_SetError("missing resource %d", i);
		goto fail;
	}

	if (flags & Cards_ColorKey) {
		if (setColorKey(cards) < 0) goto fail;
	}
	if (flags & Cards_AlphaCorners) {
		if (setAlphaCorners(cards) < 0) goto fail;
	}
	if (flags & Cards_BlackBorders) {
		if (setBlackBorders(cards) < 0) goto fail;
	}

	return cards;

fail:
	Cards_Free(cards);
	return NULL;
}

void Cards_Free(struct Cards *cards) {
	for (int i = 0; i < Cards_Count; ++i) {
		if (!cards->surfaces[i]) continue;
		SDL_FreeSurface(cards->surfaces[i]);
	}
	free(cards);
}