/*
 * parse.c
 * This file is part of LCDd, the lcdproc server.
 *
 * This file is released under the GNU General Public License. Refer to the
 * COPYING file distributed with this package.
 *
 * Copyright (c) 1999, William Ferrell, Scott Scriven
 *
 *
 * Handles input commands from clients, by splitting strings into tokens
 * and passing arguments to the appropriate handler.
 *
 * It works much like a command line.  Only the first token is used to
 * determine what function to call.
 *
 */

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

#include "shared/LL.h"
#include "shared/sockets.h"
#include "shared/report.h"
#include "clients.h"
#include "commands/command_list.h"
#include "parse.h"


#define MAX_ARGUMENTS 40



static int parse_message (const char *str, Client *c);

int
parse_all_client_messages ()
{
	Client * c;

	debug( RPT_DEBUG, "%s()", __FUNCTION__ );

	for (c = clients_getfirst(); c != NULL; c = clients_getnext()) {
		char * str;

		/* And parse all its messages...*/
		/*debug(RPT_DEBUG, "parse: Getting messages...");*/
		for (str = client_get_message (c); str != NULL; str = client_get_message (c)) {
			parse_message (str, c);
			free (str);
		}
	}
	return 0;
}

#define is_whitespace(x)	(((x) == ' ') || ((x) == '\t') || ((x) == '\r'))
#define is_final(x)		(((x) == '\n') || ((x) == '\0'))
#define is_opening_quote(x,q)   (((q) == '\0') && (((x) == '\"') || ((x) == '{')))
#define is_closing_quote(x,q)   ((((q) == '{') && ((x) == '}')) || (((q) == '\"') && ((x) == '\"')))

static int parse_message (const char *str, Client *c)
{
	typedef enum { ST_INITIAL, ST_WHITESPACE, ST_ARGUMENT, ST_FINAL } State;
	State state = ST_INITIAL;

	char errmsg[256];
	int error = 0;
	char quote = '\0';	/* The quote used to open a quote string */
	int pos = 0;
	char *arg_space;
	int argc = 0;
	char *argv[MAX_ARGUMENTS];
	int argpos = 0;

	void close_arg() {
		if (argc >= MAX_ARGUMENTS-1) {
			error = 1;
		}
		else {
			argv[argc][argpos] = '\0';
			argv[argc+1] = argv[argc] + argpos + 1;
			argc++;
			argpos = 0;
		}
	}

	debug( RPT_DEBUG, "%s( str=\"%.120s\", client=[%d] )", __FUNCTION__, str, c->sock );

	/* We will create a list of strings that is shorter or equally long as
	 * the original string str.
	 */
	arg_space = malloc(strlen(str)+1);
	if (arg_space == NULL) {
		report (RPT_ERR, "%s: Could not allocate memory", __FUNCTION__);
		sock_send_string(c->sock, "huh? error allocating memory!\n");
	}

	argv[0] = arg_space;

	while ((state != ST_FINAL) && !error) {
		char ch = str[pos++];

		switch (state) {
		  case ST_INITIAL:
		  case ST_WHITESPACE:
			if (is_whitespace(ch))
				break;
			if (is_final(ch)) {
				state = ST_FINAL;
				break;
			}	  
			/* otherwise fall through */
			state = ST_ARGUMENT;
		  case ST_ARGUMENT:
			if (is_final(ch)) {
				if (quote)
					error = 2;
				close_arg();
				state = ST_FINAL;
			}
			else if (ch == '\\') {
			 	if (str[pos]) {
			 		/* We solve quoted chars here right away */
					const char escape_chars[] = "nrt";
					const char escape_trans[] = "\n\r\t";
			 		char *p = strchr( escape_chars, str[pos] );
					
					/* Is it wise to have the characters \n, \r & \t expanded ?
					 * Can the displays deal with them ?
					 */
					if (p != NULL) {
						/* Insert a replacement for the code */
						argv[argc][argpos++] = escape_trans[p - escape_chars];
					}
					else {
						 /* Copy char literally */
						argv[argc][argpos++] = str[pos];
					}
					pos++;
			 	}
			 	else {
			 		error = 2;
					/* alternative: argv[argc][argpos++] = ch; */
			 		close_arg();
			 		state = ST_FINAL;
			 	}
			}
			else if (is_opening_quote(ch, quote)) {
				quote = ch;
			}	
			else if (is_closing_quote(ch, quote)) {
				quote = '\0';
				close_arg();
				state = ST_WHITESPACE;
			}
			else if (is_whitespace(ch) && (quote == '\0')) {
				close_arg();
				state = ST_WHITESPACE;
			}	
			else {
				argv[argc][argpos++] = ch;
			}	
			break;
		  case ST_FINAL:
		  	/* This will never be reached */
			break;
		}
	}
	if (argc < MAX_ARGUMENTS)
		argv[argc] = NULL;
	else
		error = 1;

	if (error) {
		report( RPT_WARNING, "Could not parse command from client on socket %d: %.40s", c->sock, str );
		snprintf (errmsg, sizeof(errmsg), "huh? Could not parse command\n");
		sock_send_string (c->sock, errmsg);
		free( arg_space  );
		return 0;
	}

	/* Now find and call the appropriate function...*/
	CommandFunc function = get_command_function(argv[0]);

	if (function != NULL) {
		error = function (c, argc, argv);
		if (error) {
			snprintf (errmsg, sizeof(errmsg), "huh? Function returned error \"%.40s\"\n", argv[0]);
			sock_send_string (c->sock, errmsg);
			report( RPT_WARNING, "Command function returned an error after command from client on socket %d: %.40s", c->sock, str );
		}	
	}
	else {
		snprintf (errmsg, sizeof(errmsg), "huh? Invalid command \"%.40s\"\n", argv[0]);
		sock_send_string (c->sock, errmsg);
		report( RPT_WARNING, "Invalid command from client on socket %d: %.40s", c->sock, str );
	}
		
	free( arg_space );
	return 0;
}