/*=============================================================================
 *
 * Copyright (C) 2003, 2004 Alessandro Duca
 *
 * This program 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 2
 * 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 General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 *=============================================================================
 *
 * $Id: _yenc.c,v 1.2 2004/02/18 23:06:14 cvs Exp $
 * 
 */

#include "_yenc.h"

/* Typedefs */
typedef struct {
	int crc;
	uLong bytes;
} Crc32;

/* Declarations */
static int crc_tab[256] = {
0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, 
0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, 
0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2, 
0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, 
0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172, 
0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c, 
0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 
0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, 
0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106, 
0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 
0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 
0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950, 
0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7, 
0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, 
0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 
0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81, 
0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a, 
0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84, 
0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, 
0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc, 
0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e, 
0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 
0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, 
0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28, 
0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f, 
0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 
0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242, 
0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69, 
0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 
0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 
0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, 
0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, 
0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
};
static char* argnames[] = {"infile", "outfile", "bytes", NULL};

/* Function declarations */
static void crc_init(Crc32 *, int);
static void crc_update(Crc32 *, int);
static Bool readable(FILE *);
static Bool writable(FILE *);
void init_yenc(void);
static int encode_buffer(char *, char *, int, Crc32*, int *);
static int decode_buffer(char *, char *, int, Crc32*, Bool *);
PyObject* decode_string(PyObject* ,PyObject* ,PyObject* );

/* Python API requirements */
static char encode_doc[] = "encode(input_file, output_file, <size>)";
static char decode_doc[] = "decode(input_file, output_file, <size>)";
static char encode_string_doc[] = "encode_string(input_string, output_string, startcolumn)";
static char decode_string_doc[] = "decode_string(input_string, output_string, escape)";
static PyMethodDef funcs[] = {
		{"encode", (PyCFunction) encode_file, METH_KEYWORDS | METH_VARARGS, encode_doc},
		{"decode", (PyCFunction) decode_file, METH_KEYWORDS | METH_VARARGS, decode_doc},
		{"encode_string", (PyCFunction) encode_string, METH_KEYWORDS | METH_VARARGS, encode_string_doc},
		{"decode_string", (PyCFunction) decode_string, METH_KEYWORDS | METH_VARARGS, decode_string_doc},
		{NULL, NULL, 0, NULL}
};
/* Function definitions */
static void crc_init(Crc32 *crc, int value)
{
	crc->crc = value;
	crc->bytes = 0UL;
}

static void crc_update(Crc32 *crc ,int c)
{
	crc->crc=crc_tab[(crc->crc^(c&0x000000ffL))&0xffL]^((crc->crc>>8L)&0xffffffL);
	crc->bytes++;
}

/*
 * Todo: provide alternatives for this to work on win32
 */
static Bool writable(FILE *file)
{
	int mode = fcntl(fileno(file),F_GETFL) & O_ACCMODE;
	return (mode == O_WRONLY) || (mode == O_RDWR);
}

static Bool readable(FILE *file)
{
	int mode = fcntl(fileno(file),F_GETFL) & O_ACCMODE;
	return (mode == O_RDONLY) || (mode == O_RDWR);
}
/*
 * 
 */

static int encode_buffer(
		char *input_buffer, 
		char *output_buffer, 
		int bytes, 
		Crc32 *crc, 
		int *col
		)
{
	int encoded;
	int in_ind;
	int out_ind;
	Byte byte;
		
	out_ind = 0;
	for(in_ind=0; in_ind < bytes; in_ind++) {
		byte = (Byte)( input_buffer[in_ind] + 42 );
		crc_update(crc, input_buffer[in_ind]);
		switch(byte){
			case ZERO:
			case LF:
			case CR:
			case ESC:
				goto escape_string;
			case TAB:
			case SPACE:
				if(*col == 0 || *col == LINESIZE-1) {
					goto escape_string;
				}
			default:
				goto plain_string;
		}
		escape_string:
		byte = (Byte)(byte + 64);
		output_buffer[out_ind++] = ESC;
		(*col)++;
		plain_string:
		output_buffer[out_ind++] = byte;
		(*col)++;
		encoded++;
		if(*col >= LINESIZE) {
			output_buffer[out_ind++] = CR;
			output_buffer[out_ind++] = LF;
			*col = 1;
		}
	}
	return out_ind;
}

PyObject* encode_file(
		PyObject* self,
		PyObject* args,
		PyObject* kwds
		)
{
	Byte read_buffer[BLOCK];
	Byte write_buffer[LONGBUFF];
	uLong encoded	= 0;
	int col		= 0;
	int read_bytes;
	int in_ind;
	int encoded_bytes;
	uLong bytes = 0;
	Crc32 crc;

	FILE *infile = NULL, *outfile = NULL;
	PyObject *Py_infile = NULL, *Py_outfile = NULL;
	
	if(!PyArg_ParseTupleAndKeywords(args, kwds, "O!O!|l", argnames, \
				&PyFile_Type, &Py_infile, \
				&PyFile_Type, &Py_outfile, \
				&bytes)) return NULL;

	infile = PyFile_AsFile(Py_infile);
	outfile = PyFile_AsFile(Py_outfile);
	
	if(!readable(infile) || !writable(outfile) ) {
		return PyErr_Format(PyExc_ValueError, "file objects not writeable/readable");
	} 
	
	crc_init(&crc, -1);

	while(encoded < bytes || bytes == 0){
		if( bytes && (bytes - encoded) < BLOCK) {
			in_ind = bytes - encoded;
		} else {
			in_ind = BLOCK;
		}
		read_bytes = fread(&read_buffer, 1, in_ind, infile);
		if(read_bytes < 1) break;
		encoded_bytes = encode_buffer(&read_buffer[0], &write_buffer[0], read_bytes, &crc, &col);
		if(fwrite(&write_buffer, 1, encoded_bytes, outfile) != encoded_bytes) {
			break;
		}
		encoded += read_bytes;
	}
	if(ferror(infile) || ferror(outfile)) {
		return PyErr_Format(PyExc_IOError, "I/O Error while encoding");
	}
	if(col > 0) {
		fputc( CR, outfile );
		fputc( LF, outfile );
	}
	fflush(outfile);
	return Py_BuildValue("(l,i)",encoded,(unsigned int) (crc.crc ^ 0xFFFFFFFF));
}

static int decode_buffer(
		char *input_buffer, 
		char *output_buffer, 
		int bytes, 
		Crc32 *crc, 
		Bool *escape
		)
{
	int read_ind;
	int decoded_bytes;
	Byte byte;
	
	decoded_bytes = 0;
	for(read_ind = 0; read_ind < bytes; read_ind++) {
		byte = input_buffer[read_ind];
		if(*escape) {
			byte = (Byte)( byte - 106 );
			*escape = 0;
		} else if(byte == ESC) {
			*escape = 1;
			continue;
		} else if(byte == LF || byte == CR) {
			continue;
		} else {
			byte = (Byte)( byte - 42 );
		}
		output_buffer[decoded_bytes] = byte;
		decoded_bytes++;
		crc_update(crc, byte);
	}
	return decoded_bytes;
}

PyObject* encode_string(
		PyObject* self, 
		PyObject* args, 
		PyObject* kwds
		)
{
	PyObject *Py_input_string;
	PyObject *Py_output_string;
	PyObject *retval;
	
	Byte *input_buffer = NULL;
	Byte *output_buffer = NULL;
	int crc_value = -1;
	int input_len = 0;
	int output_len = 0;
	int col = 0;
	Crc32 crc;
	
	static char *kwlist[] = { "string", "crc32", "column", NULL };
	if(!PyArg_ParseTupleAndKeywords(args, 
				kwds,
				"O!|ii", 
				kwlist,
				&PyString_Type,
				&Py_input_string, 
				&crc_value,
				&col
				)) 
		return NULL;
	crc_init(&crc, crc_value);
	input_len = PyString_Size(Py_input_string);
	input_buffer = PyString_AsString(Py_input_string);
	output_buffer = (char *) malloc(( 2 * input_len / LINESIZE + 1 ) * ( LINESIZE + 2 ));
	output_len = encode_buffer(input_buffer, output_buffer, input_len, &crc, &col);
	Py_output_string = PyString_FromStringAndSize(output_buffer, output_len);
	retval = Py_BuildValue("(S,i,i)", Py_output_string, crc.crc, col);

	free(output_buffer);
	Py_DECREF(Py_output_string);
	
	return retval;
}

PyObject* decode_file(
		PyObject* self, 
		PyObject* args, 
		PyObject* kwds
		)
{
	Byte read_buffer[BLOCK];
	Byte write_buffer[LONGBUFF];
	uLong decoded = 0;
	int decoded_bytes;
	int read_bytes;
	uLong read_max;
	
	Bool escape = 0;
	uLong bytes = 0;
	Crc32 crc;

	FILE *infile = NULL, *outfile = NULL;
	PyObject *Py_infile = NULL, *Py_outfile = NULL;
	
	if(!PyArg_ParseTupleAndKeywords(args, kwds, "O!O!|l", argnames, \
				&PyFile_Type, &Py_infile, \
				&PyFile_Type, &Py_outfile, \
				&bytes)) return NULL;

	infile = PyFile_AsFile(Py_infile);
	outfile = PyFile_AsFile(Py_outfile);

	if(!readable(infile) || !writable(outfile)) {
		return PyErr_Format(PyExc_ValueError,
				"file objects not writeable/readable");
	} 

	crc_init(&crc, -1);
	
	while(decoded < bytes || bytes == 0){
		if(bytes){
			read_max=(bytes-decoded)<BLOCK?(bytes-decoded):BLOCK;
		} else {
			read_max=BLOCK;
		};
		read_bytes = fread((Byte *)&read_buffer, 1, read_max, infile);
		if(read_bytes == 0) break;
		decoded_bytes = decode_buffer(&read_buffer[0],
				&write_buffer[0],read_bytes, &crc, &escape);
		if(fwrite(&write_buffer[0],1,decoded_bytes,outfile)!=decoded_bytes){
			break;
		}
		decoded += decoded_bytes;
	}
	if(ferror(infile) || ferror(outfile)) {
		return PyErr_Format(PyExc_IOError, "I/O Error while decoding");
	}
	fflush(outfile);
	return Py_BuildValue("(l,i)", 
			decoded,(unsigned int) (crc.crc ^ 0xFFFFFFFF));
}

PyObject* decode_string(
		PyObject* self, 
		PyObject* args, 
		PyObject* kwds
		)
{
	PyObject *Py_input_string;
	PyObject *Py_output_string;
	PyObject *retval;
	
	char *input_buffer = NULL;
	char *output_buffer = NULL;
	long crc_value = -1L;
	int input_len = 0;
	int output_len = 0;
	int escape = 0;
	Crc32 crc;
	
	static char *kwlist[] = { "string", "crc32", "escape", NULL };
	if(!PyArg_ParseTupleAndKeywords(args, 
				kwds,
				"O!|ii", 
				kwlist,
				&PyString_Type,
				&Py_input_string, 
				&crc_value,
				&escape
				)) 
		return NULL;
	crc_init(&crc, crc_value);
	input_len = PyString_Size(Py_input_string);
	input_buffer = PyString_AsString(Py_input_string);
	output_buffer = (char *) malloc( input_len );
	output_len = decode_buffer(input_buffer, output_buffer, input_len, &crc, &escape);
	Py_output_string = PyString_FromStringAndSize(output_buffer, output_len);
	retval = Py_BuildValue("(S,i,i)", Py_output_string, crc.crc, escape);
	
	free(output_buffer);
	Py_DECREF(Py_output_string);

	return retval;
}


void init_yenc()
{
	Py_InitModule3("_yenc", funcs, "Raw yenc operations");
}

