/* This file is part of vmod-binlog
   Copyright (C) 2013 Sergey Poznyakoff

   Vmod-binlog 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 3, or (at your option)
   any later version.

   Vmod-binlog 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 vmod-binlog.  If not, see <http://www.gnu.org/licenses/>.
*/
#include <config.h>
#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <inttypes.h>
#include <limits.h>
#include <arpa/inet.h>
#include <errno.h>
#include "pack.h"

/* Data format specification is a simplified form of Perl pack() template.
   It consists of a series of template letters optionally followed by
   numeric repeat count (which may be enclosed in square brackets).  The
   valid template letters are:
   
   Z  A null-terminated (ASCIZ) string of at most N-1 characters, will be
      null padded.  This letter must be followed by repeat count.

   c  A signed char (8-bit) value.
   C  An unsigned char (octet) value.

   s  A signed short (16-bit) value.
   S  An unsigned short value.

   l  A signed long (32-bit) value.
   L  An unsigned long value.

   q  A signed quad (64-bit) value.
   Q  An unsigned quad value.

   i  A signed integer value.
   I  A unsigned integer value.

   n  An unsigned short (16-bit) in "network" (big-endian) order.
   N  An unsigned long (32-bit) in "network" (big-endian) order.
   v  An unsigned short (16-bit) in "VAX" (little-endian) order.
   V  An unsigned long (32-bit) in "VAX" (little-endian) order.
   
   f  A single-precision float in native format.
   d  A double-precision float in native format.
   
   x  A null byte (a.k.a ASCII NUL, "\000", chr(0))
   X  Back up a byte.
   @  Null-fill or truncate to absolute position, counted from the
      current position.
   .  Null-fill or truncate to absolute position specified by
      the repeat count.
*/

#define F_REP 0x01

struct packspec {
	int ch;
	int flags;
	void (*packer)(struct packenv *, int);
	void (*unpacker)(struct packenv *, int);
};

struct packinst {
	struct packinst *next;
	struct packspec *spec;
	int rep;
	int cur;
};

static char *
packenv_get(struct packenv *env)
{
	if (env->argi == env->argc)
		return NULL;
	return env->argv[env->argi++];
}

static void
printunum(FILE *fp, uintmax_t num)
{
	char numbuf[512];
	char *p = numbuf + sizeof(numbuf);
	*--p = 0;
	do
		*--p = num % 10 + '0';
	while (num /= 10);
	fputs(p, fp);
}

static void
printsnum(FILE *fp, intmax_t num)
{
	if (num < 0) {
		fputc('-', fp);
		num = - num;
	}
	printunum(fp, num);
}

static int
getunum(char *s, uintmax_t maxval, uintmax_t *retval)
{
	uintmax_t x = 0;

	for (; *s && isspace(*s); s++);
	for (; *s; s++) {
		if (!isdigit(*s))
			return -1;
		x = x*10 + *s - '0';
	}
	if (x > maxval)
		return -1;
	*retval = x;
	return 0;
}

static int
getsnum(char *s, intmax_t minval, intmax_t maxval, intmax_t *retval)
{
	uintmax_t x = 0;
	int neg = 0;
	
	for (; *s && isspace(*s); s++);
	if (*s == '-') {
		neg = 1;
		++s;
	}
	for (; *s; s++) {
		if (!isdigit(*s))
			return -1;
		x = x*10 + *s - '0';
	}

	if (neg) {
		if (x > -minval)
			return -1;
		*retval = -x;
	} else if (x > maxval)
		return -1;
	else
		*retval = x;
	return 0;
}

#define GETSARG(env, type, minv, maxv) do {				\
	if ((env)->buf_base) {					        \
		char *arg = packenv_get(env);				\
		if (arg) {						\
			intmax_t x;					\
			if (getsnum(arg, minv, maxv, &x) == 0) {	\
				type v = (type) x;			\
				memcpy(env->buf_base + env->buf_pos,	\
				       &v, sizeof(v));			\
			}						\
		}							\
	}								\
 } while(0)

#define GETUARG(env, type, maxv) do {					\
	if ((env)->buf_base) {						\
		char *arg = packenv_get(env);				\
		if (arg) {						\
			uintmax_t x;					\
			if (getunum(arg, maxv, &x) == 0) {		\
				type v = (type) x;			\
				memcpy(env->buf_base + env->buf_pos,	\
				       &v, sizeof(v));			\
			}						\
		}							\
        }								\
 } while(0)


static void
Z_packer(struct packenv *env, int rep)
{
	if (env->buf_base) {
		char *arg = packenv_get(env);

		memset(env->buf_base + env->buf_pos, 0, rep);
		if (arg) {
			size_t len = strlen(arg);
			if (len > rep - 1)
				len = rep - 1;
			memcpy(env->buf_base + env->buf_pos, arg, len);
		}
	}
	env->buf_pos += rep;
}
		
static void
Z_unpacker(struct packenv *env, int rep)
{
	fprintf(env->fp, "%-*.*s", rep, rep, env->buf_base + env->buf_pos);
 	env->buf_pos += rep;
}

static void
c_packer(struct packenv *env, int rep)
{
	if (env->buf_base) {
		char *arg = packenv_get(env);
		if (arg)
			env->buf_base[env->buf_pos] = *arg;
	}
	env->buf_pos++;
}

static void
c_unpacker(struct packenv *env, int rep)
{
	fprintf(env->fp, "%c", env->buf_base[env->buf_pos++]);
}

static void
s_packer(struct packenv *env, int rep)
{
	GETSARG(env, int16_t, INT16_MIN, INT16_MAX);
	env->buf_pos += sizeof(int16_t);
}

static void
s_unpacker(struct packenv *env, int rep)
{
	printsnum(env->fp, *(int16_t *) (env->buf_base + env->buf_pos));
	env->buf_pos += sizeof(int16_t);
}

static void
S_packer(struct packenv *env, int rep)
{
	GETUARG(env, uint16_t, UINT16_MAX);
	env->buf_pos += sizeof(uint16_t);
}

static void
S_unpacker(struct packenv *env, int rep)
{
	printunum(env->fp, *(uint16_t *)(env->buf_base + env->buf_pos));
	env->buf_pos += sizeof(uint16_t);
}

static void
l_packer(struct packenv *env, int rep)
{
	GETSARG(env, int32_t, INT32_MIN, INT32_MAX);
	env->buf_pos += sizeof(int32_t);
}

static void
l_unpacker(struct packenv *env, int rep)
{
	printsnum(env->fp, *(int32_t *)(env->buf_base + env->buf_pos));
	env->buf_pos += sizeof(int32_t);
}

static void
L_packer(struct packenv *env, int rep)
{
	GETUARG(env, uint32_t, UINT32_MAX);
	env->buf_pos += sizeof(uint32_t);
}

static void
L_unpacker(struct packenv *env, int rep)
{
	printunum(env->fp, *(uint32_t *)(env->buf_base + env->buf_pos));
	env->buf_pos += sizeof(uint32_t);
}

static void
q_packer(struct packenv *env, int rep)
{
	GETSARG(env, int64_t, INT64_MIN, INT64_MAX);
	env->buf_pos += sizeof(int64_t);
}

static void
q_unpacker(struct packenv *env, int rep)
{
	printsnum(env->fp, *(int64_t *)(env->buf_base + env->buf_pos));
	env->buf_pos += sizeof(int64_t);
}

static void
Q_packer(struct packenv *env, int rep)
{
	GETUARG(env, uint64_t, UINT64_MAX);
	env->buf_pos += sizeof(uint64_t);
}

static void
Q_unpacker(struct packenv *env, int rep)
{
	printunum(env->fp, *(uint64_t *)(env->buf_base + env->buf_pos));
	env->buf_pos += sizeof(uint64_t);
}

static void
i_packer(struct packenv *env, int rep)
{
	GETSARG(env, int, INT_MIN, INT_MAX);
	env->buf_pos += sizeof(int);
}

static void
i_unpacker(struct packenv *env, int rep)
{
	printsnum(env->fp, *(int *)(env->buf_base + env->buf_pos));
	env->buf_pos += sizeof(int);
}

static void
I_packer(struct packenv *env, int rep)
{
	GETUARG(env, unsigned, UINT_MAX);
	env->buf_pos += sizeof(unsigned);
}

static void
I_unpacker(struct packenv *env, int rep)
{
	printunum(env->fp, *(unsigned *)(env->buf_base + env->buf_pos));
	env->buf_pos += sizeof(unsigned);
}

/* n - An unsigned short (16-bit) in "network" (big-endian) order. */
static void
n_packer(struct packenv *env, int rep)
{
	if (env->buf_base) {
		char *arg = packenv_get(env);
		if (arg) {
			uintmax_t x;
			if (getunum(arg, UINT16_MAX, &x) == 0) {
				uint16_t v = htons((uint16_t) x);
				memcpy(env->buf_base + env->buf_pos,
				       &v, sizeof(v));
			}
		}
        }
	env->buf_pos += sizeof(uint16_t);
}

static void
n_unpacker(struct packenv *env, int rep)
{
	uint16_t v = ntohs(*(uint16_t *)(env->buf_base + env->buf_pos));
	printunum(env->fp, v);
	env->buf_pos += sizeof(uint16_t);
}

/* N - An unsigned long (32-bit) in "network" (big-endian) order. */
static void
N_packer(struct packenv *env, int rep)
{
	if (env->buf_base) {
		char *arg = packenv_get(env);
		if (arg) {
			uintmax_t x;
			if (getunum(arg, UINT32_MAX, &x) == 0) {
				uint32_t v = htonl((uint32_t) x);
				memcpy(env->buf_base + env->buf_pos,
				       &v, sizeof(v));
			}
		}
        }
	env->buf_pos += sizeof(uint32_t);
}

static void
N_unpacker(struct packenv *env, int rep)
{
	uint32_t v = ntohl(*(uint32_t *)(env->buf_base + env->buf_pos));
	printunum(env->fp, v);
	env->buf_pos += sizeof(uint32_t);
}

/* v - An unsigned short (16-bit) in "VAX" (little-endian) order. */
static void
v_packer(struct packenv *env, int rep)
{
	if (env->buf_base) {
		char *arg = packenv_get(env);
		if (arg) {
			uintmax_t x;
			if (getunum(arg, UINT16_MAX, &x) == 0) {
				uint16_t v = ntohs((uint16_t) x);
				memcpy(env->buf_base + env->buf_pos,
				       &v, sizeof(v));
			}
		}
        }
	env->buf_pos += sizeof(uint16_t);
}

static void
v_unpacker(struct packenv *env, int rep)
{
	uint16_t v = htons(*(uint16_t *)(env->buf_base + env->buf_pos));
	printunum(env->fp, v);
	env->buf_pos += sizeof(uint16_t);
}

/* V - An unsigned long (32-bit) in "VAX" (little-endian) order. */
static void
V_packer(struct packenv *env, int rep)
{
	if (env->buf_base) {
		char *arg = packenv_get(env);
		if (arg) {
			uintmax_t x;
			if (getunum(arg, UINT32_MAX, &x) == 0) {
				uint32_t v = ntohl((uint32_t) x);
				memcpy(env->buf_base + env->buf_pos,
				       &v, sizeof(v));
			}
		}
        }
	env->buf_pos += sizeof(uint32_t);
}

static void
V_unpacker(struct packenv *env, int rep)
{
	uint32_t v = htonl(*(uint32_t *)(env->buf_base + env->buf_pos));
	printunum(env->fp, v);
	env->buf_pos += sizeof(uint32_t);
}

/* f - A single-precision float in native format. */
static void
f_packer(struct packenv *env, int rep)
{
	if (env->buf_base) {
		char *arg = packenv_get(env);
		if (arg) {
			float v;
			char *p;
			
			errno = 0;
			v = strtof(arg, &p);
			if (*p == 0 && errno == 0)
				memcpy(env->buf_base + env->buf_pos,
				       &v, sizeof(v));
		}
	}
	env->buf_pos += sizeof(float);
}

static void
f_unpacker(struct packenv *env, int rep)
{
	float v = *(float *)(env->buf_base + env->buf_pos);
	fprintf(env->fp, "%f", v); /* FIXME: Format? */
	env->buf_pos += sizeof(uint32_t);
}

/* d - A double-precision float in native format. */
static void
d_packer(struct packenv *env, int rep)
{
	if (env->buf_base) {
		char *arg = packenv_get(env);
		if (arg) {
			double v;
			char *p;
			
			errno = 0;
			v = strtod(arg, &p);
			if (*p == 0 && errno == 0)
				memcpy(env->buf_base + env->buf_pos,
				       &v, sizeof(v));
		}
	}
	env->buf_pos += sizeof(double);
}

static void
d_unpacker(struct packenv *env, int rep)
{
	double v = *(double *)(env->buf_base + env->buf_pos);
	fprintf(env->fp, "%g", v); /* FIXME: Format? */
	env->buf_pos += sizeof(double);
}

static void
x_packer(struct packenv *env, int rep)
{
	if (env->buf_base)
		env->buf_base[env->buf_pos] = 0;
	env->buf_pos++;
}

static void
x_unpacker(struct packenv *env, int rep)
{
	fputc(0, env->fp);
}

static void
X_packer(struct packenv *env, int rep)
{
	if (env->buf_pos)
		--env->buf_pos;
}

static void
at_packer(struct packenv *env, int rep)
{
	if (env->buf_base)
		memset(env->buf_base + env->buf_pos, 0, rep);
	env->buf_pos += rep;
}

static void
at_unpacker(struct packenv *env, int rep)
{
	env->buf_pos += rep;
}

static void
dot_packer(struct packenv *env, int rep)
{
	if (env->buf_base) {
		if (rep < env->buf_pos)
			memset(env->buf_base + rep, 0, env->buf_pos - rep);
		else
			memset(env->buf_base + env->buf_pos, 0,
			       rep - env->buf_pos);
	}
	env->buf_pos = rep;
}

static void
dot_unpacker(struct packenv *env, int rep)
{
	env->buf_pos = rep;
}

static struct packspec packspec[] = {
	{ 'Z', F_REP, Z_packer, Z_unpacker },
	{ 'c', 0, c_packer, c_unpacker },
	{ 's', 0, s_packer, s_unpacker },
	{ 'S', 0, S_packer, S_unpacker },
	{ 'l', 0, l_packer, l_unpacker },
	{ 'L', 0, L_packer, L_unpacker },
	{ 'q', 0, q_packer, q_unpacker },
	{ 'Q', 0, Q_packer, Q_unpacker },
	{ 'i', 0, i_packer, i_unpacker },
	{ 'I', 0, I_packer, I_unpacker },
	{ 'n', 0, n_packer, n_unpacker },
	{ 'N', 0, N_packer, N_unpacker },
	{ 'v', 0, v_packer, v_unpacker },
	{ 'V', 0, V_packer, V_unpacker },
	{ 'f', 0, f_packer, f_unpacker },
	{ 'd', 0, d_packer, d_unpacker },

	{ 'x', 0, x_packer, x_unpacker },
	{ 'X', 0, X_packer, X_packer },
	{ '@', F_REP, at_packer, at_unpacker },
	{ '.', F_REP, dot_packer, dot_unpacker },
	
	{ 0 }
};

static int
getrep(const char *s, char const **endp, int *rep)
{
	int n;
	char *p;

	if (*s == '[') {
		if (s[1]) {
			if (isdigit(s[1])) {
				n = strtol(s + 1, &p, 10);
				if (n <= 0) {
					*endp = s;
					return -1;
				} else if (*p != ']') {
					*endp = p;
					return -1;
				}
				*rep = n;
				*endp = p + 1;
			} else {
				*endp = s;
				return -1;
			}
		} else {
			*endp = s;
			return -1;
		}
	} else if (isdigit(*s)) {
		n = strtol(s, &p, 10);
		if (n <= 0) {
			*endp = s;
			return -1;
		}
		*rep = n;
		*endp = p;
	} else {
		*rep = 1;
		*endp = s;
	}
	return 0;
}

struct packinst *
packcomp(const char *s, char **endp)
{
	struct packinst *head = NULL, *tail = NULL, *pi;
	struct packspec *ps;
	int rep;
	
	while (s) {
		for (ps = packspec; ps->ch; ps++)
			if (ps->ch == *s)
				break;
		if (!ps->ch)
			break;
		if (getrep(s + 1, &s, &rep))
			break;
		pi = malloc(sizeof(*pi));
		if (!pi)
			return NULL;
		pi->next = NULL;
		pi->spec = ps;
		pi->rep = rep;
		if (tail)
			tail->next = pi;
		else
			head = pi;
		tail = pi; 
	}
	if (endp)
		*endp = (char*) s;
	return head;
}

void
packfree(struct packinst *pi)
{
	while (pi) {
		struct packinst *next = pi->next;
		free(pi);
		pi = next;
	}
}

void
packin(struct packinst *pi, struct packenv *env)
{
	int i;
	
	for (; pi; pi = pi->next) {
		if (pi->spec->flags & F_REP)
			pi->spec->packer(env, pi->rep);
		else
			for (i = 0; i < pi->rep; i++)
				pi->spec->packer(env, 1);
	}
}

struct packinst *
packinnext(struct packinst *pi, struct packenv *env)
{
	int i;

	if (!pi)
		return NULL;
	if (pi->spec->flags & F_REP)
		pi->spec->packer(env, pi->rep);
	else {
		pi->spec->packer(env, 1);
		if (++pi->cur < pi->rep)
			return pi;
	}
	return packinit(pi->next);
}

void
packout(struct packinst *pi, struct packenv *env)
{
	int i;

	for (; pi; pi = pi->next) {
		if (pi->spec->flags & F_REP)
			pi->spec->unpacker(env, pi->rep);
		else
			for (i = 0; i < pi->rep; i++) {
				if (i > 0)
					fputc(' ', env->fp);
				pi->spec->unpacker(env, 1);
			}
		if (pi->next)
			fputc(' ', env->fp);
	}
}

size_t
packsize(struct packinst *pi)
{
	struct packenv env;

	memset(&env, 0, sizeof env);
	packin(pi, &env);
	return env.buf_pos;
}

struct packinst *
packinit(struct packinst *inst)
{
	if (inst)
		inst->cur = 0;
	return inst;
}

struct packenv *
packenv_create(size_t size)
{
	struct packenv *env = calloc(1, sizeof(*env));
	if (env) {
		env->buf_base = calloc(1, size);
		if (!env->buf_base) {
			free(env);
			return NULL;
		}
		env->buf_size = size;
	}
	return env;
}

void
packenv_free(struct packenv *env)
{
	if (!env)
		return;
	free(env->buf_base);
	free(env);
}

void
packenv_init(struct packenv *env)
{
	memset(env->buf_base, 0, env->buf_size);
	env->buf_pos = 0;
}

#ifdef STANDALONE
#include <unistd.h>

int
main(int argc, char **argv)
{
	void (*fn)(struct packinst *pi, struct packenv *env) = packin;
	struct packinst *pi;
	struct packenv *env;
	char *end;
	int c;
	
	while ((c = getopt(argc, argv, "d")) != EOF) {
		switch (c) {
		case 'd':
			fn = packout;
			break;
		default:
			exit(1);
		}
	}

	argc -= optind;
	argv += optind;

	if (argc == 0)
		abort();

	pi = packcomp(argv[0], &end);
	if (!pi) {
		fprintf(stderr, "out of memory\n");
		abort();
	}
	if (*end) {
		fprintf(stderr, "compile error near %s\n", end);
		exit(1);
	}
	env = packenv_create(packsize(pi));
	if (!env)  {
		fprintf(stderr, "out of memory\n");
		abort();
	}
		
	env->fp = stdout;
	env->argv = argv + 1;
	env->argc = argc - 1;

	if (fn == packout)
		fread(env->buf_base, env->buf_size, 1, stdin);
	
	fn(pi, env);
	if (fn == packin) {
		fwrite(env->buf_base, env->buf_size, 1, stdout);
	}
	
	packenv_free(env);
	packfree(pi);
}
#endif