/***************************************************************************
 decompress1.c Copyright (C) 1999 The FreeSCI project


 This program may be modified and copied freely according to the terms of
 the GNU general public license (GPL), as long as the above copyright
 notice and the licensing information contained herein are preserved.

 Please refer to www.gnu.org for licensing details.

 This work is provided AS IS, without warranty of any kind, expressed or
 implied, including but not limited to the warranties of merchantibility,
 noninfringement, and fitness for a specific purpose. The author will not
 be held liable for any damage caused by this work or derivatives of it.

 By using this source code, you agree to the licensing terms as stated
 above.


 Please contact the maintainer for bug reports or inquiries.

 Current Maintainer:

    Christoph Reichenbach (CJR) [creichen@rbg.informatik.tu-darmstadt.de]

***************************************************************************/
/* Reads data from a resource file and stores the result in memory */

#include <sci_memory.h>
#include <sciresource.h>



/* DEFLATE-DCL
** Refer to the FreeSCI docs for a full description.
*/

#define HUFFMAN_LEAF 0x40000000

struct bit_read_struct {
	int length;
	int bitpos;
	int bytepos;
	byte *data;
};

#define BRANCH_SHIFT 12
#define BRANCH_NODE(pos, left, right)  ((left << BRANCH_SHIFT) | (right)),
#define LEAF_NODE(pos, value)  ((value) | HUFFMAN_LEAF),


static int length_tree[] = {
#include "treedef.1"
	0 /* We need something witout a comma at the end */
};

static int distance_tree[] = {
#include "treedef.2"
	0 /* We need something witout a comma at the end */
};

static int ascii_tree[] = {
#include "treedef.3"
	0 /* We need something witout a comma at the end */
};

#define CALLC(x) { if ((x) == -SCI_ERROR_DECOMPRESSION_OVERFLOW) return -SCI_ERROR_DECOMPRESSION_OVERFLOW; }

static inline int
getbits_msb_first(struct bit_read_struct *inp, int bits)
{
	int morebytes = (bits + inp->bitpos - 1) >> 3;
	int result = 0;
	int i;

	if (inp->bytepos + morebytes >= inp->length) {
		fprintf(stderr,"read out-of-bounds with bytepos %d + morebytes %d >= length %d\n",
			inp->bytepos, morebytes, inp->length);
		return -SCI_ERROR_DECOMPRESSION_OVERFLOW;
	}

	for (i = 0; i <= morebytes; i++)
		result |= (inp->data[inp->bytepos + i]) << (i << 3);

	result >>= inp->bitpos;
	result &= ~(~0 << bits);

	inp->bitpos += bits - (morebytes << 3);
	inp->bytepos += morebytes;

	return result;
}

static int DEBUG_DCL_INFLATE = 0; /* FIXME: Make this a define eventually */

static inline int
getbits(struct bit_read_struct *inp, int bits)
{
	int morebytes = (bits + inp->bitpos - 1) >> 3;
	int result = 0;
	int i;

	if (inp->bytepos + morebytes >= inp->length) {
		fprintf(stderr,"read out-of-bounds with bytepos %d + morebytes %d >= length %d\n",
			inp->bytepos, morebytes, inp->length);
		return -SCI_ERROR_DECOMPRESSION_OVERFLOW;
	}

	for (i = 0; i <= morebytes; i++)
		result |= (inp->data[inp->bytepos + i]) << (i << 3);

	result >>= inp->bitpos;
	result &= ~((~0) << bits);

	inp->bitpos += bits - (morebytes << 3);
	inp->bytepos += morebytes;

	if (DEBUG_DCL_INFLATE)
		fprintf(stderr,"(%d:%04x)", bits, result);

	return result;
}

static int
huffman_lookup(struct bit_read_struct *inp, int *tree)
{
	int pos = 0;
	int bit;

	while (!(tree[pos] & HUFFMAN_LEAF)) {
		CALLC(bit = getbits(inp, 1));
		if (DEBUG_DCL_INFLATE)
			fprintf(stderr,"[%d]:%d->", pos, bit);
		if (bit)
			pos = tree[pos] & ~(~0 << BRANCH_SHIFT);
		else
			pos = tree[pos] >> BRANCH_SHIFT;
	}
	if (DEBUG_DCL_INFLATE)
		fprintf(stderr,"=%02x\n", tree[pos] & 0xffff);
	return tree[pos] & 0xffff;
}

#define VALUE_M(i) ((i == 0)? 7 : (VALUE_M(i - 1) + 2**i));

#define DCL_ASCII_MODE 1

static int
decrypt4_hdyn(byte *dest, int length, struct bit_read_struct *reader)
{
	int mode, length_param, value, val_length, val_distance;
	int write_pos = 0;
	int M[] = {0x07, 0x08, 0x0A, 0x0E, 0x16, 0x26, 0x46, 0x86, 0x106};

	CALLC(mode = getbits(reader, 8));
	CALLC(length_param = getbits(reader, 8));

	if (mode == DCL_ASCII_MODE) {
		fprintf(stderr,"DCL-INFLATE: Warning: Decompressing ASCII mode (untested)\n");
		/*		DEBUG_DCL_INFLATE = 1; */
	} else if (mode) {
		fprintf(stderr,"DCL-INFLATE: Error: Encountered mode %02x, expected 00 or 01\n", mode);
		return 1;
	}

	if (DEBUG_DCL_INFLATE) {
		int i;
		for (i = 0; i < reader->length; i++) {
			fprintf(stderr,"%02x ", reader->data[i]);
			if (!((i+1) & 0x1f))
				fprintf(stderr,"\n");
		}


		fprintf(stderr,"\n---\n");
	}


	if (length_param < 3 || length_param > 6)
		fprintf(stderr,"Warning: Unexpected length_param value %d (expected in [3,6])\n", length_param);

	while (write_pos < length) {
		CALLC(value = getbits(reader, 1));

		if (value) { /* (length,distance) pair */
			int val_length_backup;

			CALLC(value = huffman_lookup(reader, length_tree));

			if (value < 8)
				val_length = value + 2;
			else {
				int length_bonus;

				val_length = M[value - 7] + 2;
				CALLC(length_bonus = getbits(reader, value - 7));
				val_length += length_bonus;
			}

			if (DEBUG_DCL_INFLATE)
				fprintf(stderr," | ");

			CALLC(value = huffman_lookup(reader, distance_tree));

			if (val_length == 2) {
				val_distance = value << 2;

				CALLC(value = getbits(reader, 2));
				val_distance |= value;
			} else {
				val_distance = value << length_param;

				CALLC(value = getbits(reader, length_param));
				val_distance |= value;
			}
			++val_distance;

			if (DEBUG_DCL_INFLATE)
				fprintf(stderr,"\nCOPY(%d from %d)\n", val_length, val_distance);

			if (val_length + write_pos > length) {
				fprintf(stderr, "DCL-INFLATE Error: Write out of bounds while copying %d bytes\n", val_length);
				return -SCI_ERROR_DECOMPRESSION_OVERFLOW;
			}

			if (write_pos < val_distance) {
				fprintf(stderr, "DCL-INFLATE Error: Attempt to copy from before beginning of input stream\n");
				return -SCI_ERROR_DECOMPRESSION_INSANE;
			}

			val_length_backup = val_length;

			while (val_length) {
				int copy_length = (val_length > val_distance)? val_distance : val_length;

				memcpy(dest + write_pos, dest + write_pos - val_distance, copy_length);

				if (DEBUG_DCL_INFLATE) {
					int i;
					for (i = 0; i < copy_length; i++)
						fprintf(stderr,"\33[32;31m%02x\33[37;37m ", dest[write_pos + i]);
					fprintf(stderr, "\n");
				}

				val_length -= copy_length;
			}

			write_pos += val_length_backup;

		} else { /* Copy byte verbatim */
			if (mode == DCL_ASCII_MODE) {
				CALLC(value = huffman_lookup(reader, ascii_tree));
			} else {
				CALLC(value = getbits(reader, 8));
			}

			dest[write_pos++] = value;

			if (DEBUG_DCL_INFLATE)
				fprintf(stderr, "\33[32;31m%02x \33[37;37m", value);
		}
	}

	return 0;
}

int
decrypt4(guint8* dest, guint8* src, int length, int complength)
{
	struct bit_read_struct reader;

	reader.length = complength;
	reader.bitpos = 0;
	reader.bytepos = 0;
	reader.data = src;

	return -decrypt4_hdyn(dest, length, &reader);
}




void decryptinit3();
int decrypt3(guint8* dest, guint8* src, int length, int complength);
int decompress1(resource_t *result, int resh, int early);

int decompress1e(resource_t *result, int resh)
{
  return decompress1(result, resh, 1);
}

int decompress1l(resource_t *result, int resh)
{
  return decompress1(result, resh, 0);
}


int decompress1(resource_t *result, int resh, int early)
{
	guint16 compressedLength;
	guint16 compressionMethod, result_size;
	guint8 *buffer;
	guint8 tempid;

	if (early) {
		if (read(resh, &(result->id),2) != 2)
			return SCI_ERROR_IO_ERROR;

#ifdef WORDS_BIGENDIAN
		result->id = GUINT16_SWAP_LE_BE_CONSTANT(result->id);
#endif

		result->number = result->id & 0x07ff;
		result->type = result->id >> 11;

		if ((result->number >= sci_max_resource_nr[SCI_VERSION_1_EARLY]) || (result->type > sci_invalid_resource))
			return SCI_ERROR_DECOMPRESSION_INSANE;
	} else {
		if (read(resh, &tempid, 1) != 1)
			return SCI_ERROR_IO_ERROR;

		result->id = tempid;

		result->type = result->id &0x7f;
		if (read(resh, &(result->number), 2) != 2)
			return SCI_ERROR_IO_ERROR;

#ifdef WORDS_BIGENDIAN
		result->number = GUINT16_SWAP_LE_BE_CONSTANT(result->number);
#endif /* WORDS_BIGENDIAN */
		if ((result->number >= sci_max_resource_nr[SCI_VERSION_1_LATE]) || (result->type > sci_invalid_resource))
			return SCI_ERROR_DECOMPRESSION_INSANE;
	}

	if ((read(resh, &compressedLength, 2) != 2) ||
	    (read(resh, &result_size, 2) != 2) ||
	    (read(resh, &compressionMethod, 2) != 2))
		return SCI_ERROR_IO_ERROR;

#ifdef WORDS_BIGENDIAN
	compressedLength = GUINT16_SWAP_LE_BE_CONSTANT(compressedLength);
	result_size = GUINT16_SWAP_LE_BE_CONSTANT(result_size);
	compressionMethod = GUINT16_SWAP_LE_BE_CONSTANT(compressionMethod);
#endif
	result->size = result_size;

	if ((result->size > SCI_MAX_RESOURCE_SIZE) ||
	    (compressedLength > SCI_MAX_RESOURCE_SIZE))
		return SCI_ERROR_RESOURCE_TOO_BIG;

	if (compressedLength > 4)
		compressedLength -= 4;
	else { /* Object has size zero (e.g. view.000 in sq3) (does this really exist?) */
		result->data = 0;
		result->status = SCI_STATUS_NOMALLOC;
		return SCI_ERROR_EMPTY_OBJECT;
	}

	buffer = sci_malloc(compressedLength);
	result->data = sci_malloc(result->size);

	if (read(resh, buffer, compressedLength) != compressedLength) {
		free(result->data);
		free(buffer);
		return SCI_ERROR_IO_ERROR;
	};


#ifdef _SCI_DECOMPRESS_DEBUG
	fprintf(stderr, "Resource %i.%s encrypted with method SCI1%c/%hi at %.2f%%"
		" ratio\n",
		result->number, sci_resource_type_suffixes[result->type],
		early? 'e' : 'l',
		compressionMethod,
		(result->size == 0)? -1.0 :
		(100.0 * compressedLength / result->size));
	fprintf(stderr, "  compressedLength = 0x%hx, actualLength=0x%hx\n",
		compressedLength, result->size);
#endif

	switch(compressionMethod) {

	case 0: /* no compression */
		if (result->size != compressedLength) {
			free(result->data);
			result->data = NULL;
			result->status = SCI_STATUS_NOMALLOC;
			free(buffer);
			return SCI_ERROR_DECOMPRESSION_OVERFLOW;
		}
		memcpy(result->data, buffer, compressedLength);
		result->status = SCI_STATUS_ALLOCATED;
		break;

	case 1: /* LZW */
		if (decrypt2(result->data, buffer, result->size, compressedLength)) {
			free(result->data);
			result->data = 0; /* So that we know that it didn't work */
			result->status = SCI_STATUS_NOMALLOC;
			free(buffer);
			return SCI_ERROR_DECOMPRESSION_OVERFLOW;
		}
		result->status = SCI_STATUS_ALLOCATED;
		break;

	case 2: /* ??? */
		decryptinit3();
		if (decrypt3(result->data, buffer, result->size, compressedLength)) {
			free(result->data);
			result->data = 0; /* So that we know that it didn't work */
			result->status = SCI_STATUS_NOMALLOC;
			free(buffer);
			return SCI_ERROR_DECOMPRESSION_OVERFLOW;
		}
		result->status = SCI_STATUS_ALLOCATED;
		break;

	case 3: /* Some sort of Huffman encoding */
		if (decrypt4(result->data, buffer, result->size, compressedLength)) {
			free(result->data);
			result->data = 0; /* So that we know that it didn't work */
			result->status = SCI_STATUS_NOMALLOC;
			free(buffer);
			return SCI_ERROR_DECOMPRESSION_OVERFLOW;
		}
		result->status = SCI_STATUS_ALLOCATED;
		break;

	case 4: /* NYI */
		fprintf(stderr,"Resource %d.%s: Warning: compression type #%d not yet implemented\n",
			result->number, sci_resource_type_suffixes[result->type], compressionMethod);
		free(result->data);
		result->data = NULL;
		result->status = SCI_STATUS_NOMALLOC;
		break;

	default:
		fprintf(stderr,"Resource %d.%s: Compression method SCI1/%hi not "
			"supported!\n", result->number, sci_resource_type_suffixes[result->type],
			compressionMethod);
		free(result->data);
		result->data = 0; /* So that we know that it didn't work */
		result->status = SCI_STATUS_NOMALLOC;
		free(buffer);
		return SCI_ERROR_UNKNOWN_COMPRESSION;
	}

	free(buffer);
	return 0;
}