/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2002, Christos Ricudis
 *
 * Christos Ricudis <ricudis@itc.auth.gr>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * \brief Connect to PostgreSQL
 *
 * \author Christos Ricudis <ricudis@itc.auth.gr>
 *
 * \ingroup applications
 */

#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <stdio.h>
#include <unistd.h>

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision$")

#include "asterisk/file.h"
#include "asterisk/logger.h"
#include "asterisk/channel.h"
#include "asterisk/pbx.h"
#include "asterisk/module.h"
#include "asterisk/linkedlists.h"
#include "asterisk/chanvars.h"
#include "asterisk/lock.h"
#include "asterisk/utils.h"

#include "libpq-fe.h"

static char *tdesc = "Simple PostgreSQL Interface";

static char *app = "PGSQL";

static char *synopsis = "Do several SQLy things";

static char *descrip =
"PGSQL():  Do several SQLy things\n"
"Syntax:\n"
"  PGSQL(Connect var option-string)\n"
"    Connects to a database.  Option string contains standard PostgreSQL\n"
"    parameters like host=, dbname=, user=.  Connection identifier returned\n"
"    in ${var}.\n"
"  PGSQL(Query var ${connection_identifier} query-string)\n"
"    Executes standard SQL query contained in query-string using established\n"
"    connection identified by ${connection_identifier}.  Result of query is\n"
"    stored in ${var}.\n"
"  PGSQL(Fetch statusvar ${result_identifier} var1 var2 ... varn)\n"
"    Fetches a single row from a result set contained in ${result_identifier}.\n"
"    Assigns returned fields to ${var1} ... ${varn}.  ${statusvar} is set TRUE\n"
"    if additional rows exist in result set.\n"
"  PGSQL(Clear ${result_identifier})\n"
"    Frees memory and data structures associated with result set.\n"
"  PGSQL(Disconnect ${connection_identifier})\n"
"    Disconnects from named connection to PostgreSQL.\n" ;

/*

Syntax of SQL commands :

	Connect var option-string

	Connects to a database using the option-string and stores the
	connection identifier in ${var}


	Query var ${connection_identifier} query-string

	Submits query-string to database backend and stores the result
	identifier in ${var}


	Fetch statusvar ${result_identifier} var1 var2 var3 ... varn

	Fetches a row from the query and stores end-of-table status in
	${statusvar} and columns in ${var1} ... ${varn}


	Clear ${result_identifier}

	Clears data structures associated with ${result_identifier}


	Disconnect ${connection_identifier}

	Disconnects from named connection


EXAMPLES OF USE :

exten => s,2,PGSQL(Connect connid host=localhost user=asterisk dbname=credit)
exten => s,3,PGSQL(Query resultid ${connid} SELECT username,credit FROM credit WHERE callerid=${CALLERIDNUM})
exten => s,4,PGSQL(Fetch fetchid ${resultid} datavar1 datavar2)
exten => s,5,GotoIf(${fetchid}?6:8)
exten => s,6,Festival("User ${datavar1} currently has credit balance of ${datavar2} dollars.")
exten => s,7,Goto(s,4)
exten => s,8,PGSQL(Clear ${resultid})
exten => s,9,PGSQL(Disconnect ${connid})

*/

STANDARD_LOCAL_USER;

LOCAL_USER_DECL;

enum id_type {
	AST_PGSQL_ID_DUMMY = 0,
	AST_PGSQL_ID_CONNID,
	AST_PGSQL_ID_RESID,
	AST_PGSQL_ID_FETCHID
};

struct ast_PGSQL_id {
	enum id_type identifier_type; /* 0 = dummy, 1 = connid, 2 = resultid, 3 = fetchid */
	int identifier;
	void *data;
	AST_LIST_ENTRY(ast_PGSQL_id) entries;
} *ast_PGSQL_id;

AST_LIST_HEAD(PGSQLidshead, ast_PGSQL_id) PGSQLidshead;

static void *find_identifier(const int identifier, const enum id_type identifier_type)
{
	struct PGSQLidshead *headp;
	struct ast_PGSQL_id *i;
	void *res = NULL;
	int found = 0;

	headp = &PGSQLidshead;

	if (AST_LIST_LOCK(headp)) {
		ast_log(LOG_WARNING, "Unable to lock identifiers list\n");
	} else {
		AST_LIST_TRAVERSE(headp, i, entries) {
			if ((i->identifier == identifier) && (i->identifier_type == identifier_type)) {
				found = 1;
				res = i->data;
				break;
			}
		}
		if (!found) {
			ast_log(LOG_WARNING, "Identifier %d, identifier_type %d not found in identifier list\n", identifier, identifier_type);
		}
		AST_LIST_UNLOCK(headp);
	}

	return res;
}

static int add_identifier(const enum id_type identifier_type, void *data)
{
	struct ast_PGSQL_id *i, *j;
	struct PGSQLidshead *headp;
	int maxidentifier = 0;

	headp = &PGSQLidshead;
	i = NULL;
	j = NULL;

	if (AST_LIST_LOCK(headp)) {
		ast_log(LOG_WARNING, "Unable to lock identifiers list\n");
		return -1;
	}

	if (!(i = ast_malloc(sizeof(*i)))) {
		AST_LIST_UNLOCK(headp);
		return -1;
	}
	
	AST_LIST_TRAVERSE(headp, j, entries) {
		if (j->identifier > maxidentifier)
			maxidentifier = j->identifier;
	}
	i->identifier = maxidentifier + 1;
	i->identifier_type = identifier_type;
	i->data = data;
	AST_LIST_INSERT_HEAD(headp, i, entries);
	AST_LIST_UNLOCK(headp);

	return i->identifier;
}

static int del_identifier(const int identifier, const enum id_type identifier_type)
{
	struct ast_PGSQL_id *i;
	struct PGSQLidshead *headp;
	int found = 0;

	headp = &PGSQLidshead;

	if (AST_LIST_LOCK(headp)) {
		ast_log(LOG_WARNING, "Unable to lock identifiers list\n");
	} else {
		AST_LIST_TRAVERSE(headp, i, entries) {
			if ((i->identifier == identifier) && (i->identifier_type == identifier_type)) {
				AST_LIST_REMOVE(headp, i, entries);
				free(i);
				found = 1;
				break;
			}
		}
		AST_LIST_UNLOCK(headp);
	}

	if (!found) {
		ast_log(LOG_WARNING, "Could not find identifier %d, identifier_type %d in list to delete\n", identifier, identifier_type);
		return -1;
	} else {
		return 0;
	}
}

static int aPGSQL_connect(struct ast_channel *chan, void *data)
{
	char s[100] = "";
	char *optionstring;
	char *var;
	int res = 0;
	PGconn *PGSQLconn;
	int id;
	char *stringp = NULL;

	if (!(stringp = ast_strdupa(data)))
		return -1;
	
	strsep(&stringp, " "); /* eat the first token, we already know it :P  */
	var = strsep(&stringp, " ");
	optionstring = strsep(&stringp, "\n");

	PGSQLconn = PQconnectdb(optionstring);
	if (PQstatus(PGSQLconn) == CONNECTION_BAD) {
		ast_log(LOG_WARNING, "Connection to database using '%s' failed. postgress reports : %s\n", optionstring, PQerrorMessage(PGSQLconn));
		res = -1;
	} else {
		ast_log(LOG_WARNING, "Adding identifier\n");
		id = add_identifier(AST_PGSQL_ID_CONNID, PGSQLconn);
		snprintf(s, sizeof(s), "%d", id);
		pbx_builtin_setvar_helper(chan, var, s);
	}

	return res;
}

static int aPGSQL_query(struct ast_channel *chan, void *data)
{
	char *s2, *s3;
	char s[100] = "";
	char *querystring;
	char *var;
	int res = 0, nres;
	PGconn *PGSQLconn;
	PGresult *PGSQLres;
	int id, id1;
	char *stringp = NULL;

	if (!(stringp = ast_strdupa(data)))
		return -1;
	
	strsep(&stringp, " "); /* eat the first token, we already know it :P  */
	s2 = strsep(&stringp, " ");
	while (1) {	/* ugly trick to make branches with break; */
		var = s2;
		s3 = strsep(&stringp, " ");
		id = atoi(s3);
		querystring = strsep(&stringp, "\n");
		if (!(PGSQLconn = find_identifier(id, AST_PGSQL_ID_CONNID))) {
			ast_log(LOG_WARNING, "Invalid connection identifier %d passed in aPGSQL_query\n", id);
			res = -1;
			break;
		}
		if (!(PGSQLres = PQexec(PGSQLconn, querystring))) {
			ast_log(LOG_WARNING, "aPGSQL_query: Connection Error (connection identifier = %d, error message : %s)\n", id, PQerrorMessage(PGSQLconn));
			res = -1;
			break;
		}
		if (PQresultStatus(PGSQLres) == PGRES_BAD_RESPONSE ||
		    PQresultStatus(PGSQLres) == PGRES_NONFATAL_ERROR ||
		    PQresultStatus(PGSQLres) == PGRES_FATAL_ERROR) {
		    	ast_log(LOG_WARNING, "aPGSQL_query: Query Error (connection identifier : %d, error message : %s)\n", id, PQcmdStatus(PGSQLres));
		    	res = -1;
		    	break;
		}
		nres = PQnfields(PGSQLres);
		id1 = add_identifier(AST_PGSQL_ID_RESID, PGSQLres);
		snprintf(s, sizeof(s), "%d", id1);
		pbx_builtin_setvar_helper(chan, var, s);
	 	break;
	}

	return res;
}

static int aPGSQL_fetch(struct ast_channel *chan, void *data)
{
	char *s2, *s3, *s4, *fetchid_var;
	const char *s5 = NULL;
	char s[100];
	char *var;
	int res = 0;
	PGresult *PGSQLres;
	int id, id1, i, j, fnd;
	int *identp = NULL;
	int nres;
	struct ast_var_t *variables;
	struct varshead *headp;
	char *stringp = NULL;

	headp = &chan->varshead;

	if (!(stringp = ast_strdupa(data)))
		return -1;
	
	strsep(&stringp, " "); /* eat the first token, we already know it :P  */
	fetchid_var = strsep(&stringp, " ");
	while (1) {	/* ugly trick to make branches with break; */
		var = fetchid_var; /* fetchid */
		fnd = 0;

		AST_LIST_TRAVERSE(headp, variables, entries) {
			if (!(strncasecmp(ast_var_name(variables), fetchid_var, strlen(fetchid_var)))) {
				s5 = ast_var_value(variables);
				fnd = 1;
				break;
			}
		}

		if (!fnd) {
			s5 = "0";
			pbx_builtin_setvar_helper(chan, fetchid_var, s5);
		}

		s2 = strsep(&stringp, " ");
		id = atoi(s2); /* resultid */
		if (!(PGSQLres = find_identifier(id, AST_PGSQL_ID_RESID))) {
			ast_log(LOG_WARNING, "Invalid result identifier %d passed in aPGSQL_fetch\n", id);
			res = -1;
			break;
		}
		id = atoi(s5); /*fetchid */
		if (!(identp = find_identifier(id, AST_PGSQL_ID_FETCHID))) {
			i = 0; /* fetching the very first row */
		} else {
			i = *identp;
			free(identp);
			del_identifier(id, AST_PGSQL_ID_FETCHID); /* will re-add it a bit later */
		}

		if (i < PQntuples(PGSQLres)) {
			nres = PQnfields(PGSQLres);
			ast_log(LOG_WARNING, "ast_PGSQL_fetch : nres = %d i = %d ;\n", nres, i);
			for (j = 0; j < nres; j++) {
				if (!(s3 = strsep(&stringp, " "))) {
					ast_log(LOG_WARNING, "ast_PGSQL_fetch : More tuples (%d) than variables (%d)\n", nres, j);
					break;
				}
				if (!(s4 = PQgetvalue(PGSQLres, i, j))) {
					ast_log(LOG_WARNING, "PQgetvalue(res, %d, %d) returned NULL in ast_PGSQL_fetch\n", i, j);
					break;
				}
				ast_log(LOG_WARNING, "===setting variable '%s' to '%s'\n", s3, s4);
				pbx_builtin_setvar_helper(chan, s3, s4);
			}
			if (!(identp = ast_malloc(sizeof(int))))
				return -1;
			*identp = ++i; /* advance to the next row */
			id1 = add_identifier(AST_PGSQL_ID_FETCHID, identp);
		} else {
			ast_log(LOG_WARNING, "ast_PGSQL_fetch : EOF\n");
			id1 = 0; /* no more rows */
		}
		snprintf(s, sizeof(s), "%d", id1);
		ast_log(LOG_WARNING, "Setting var '%s' to value '%s'\n", fetchid_var, s);
		pbx_builtin_setvar_helper(chan, fetchid_var, s);
		break;
	}

	return res;
}

static int aPGSQL_reset(struct ast_channel *chan, void *data)
{
	char *s;
	PGconn *PGSQLconn;
	int id;
	char *stringp = NULL;

	if (!(stringp = ast_strdupa(data)))
		return -1;

	strsep(&stringp, " "); /* eat the first token, we already know it :P  */
	s = strsep(&stringp, " ");
	id = atoi(s);
	if (!(PGSQLconn = find_identifier(id, AST_PGSQL_ID_CONNID))) {
		ast_log(LOG_WARNING, "Invalid connection identifier %d passed in aPGSQL_reset\n", id);
	} else {
		PQreset(PGSQLconn);
	}
	
	return 0;
}

static int aPGSQL_clear(struct ast_channel *chan, void *data)
{
	char *s;
	PGresult *PGSQLres;
	int id;
	char *stringp = NULL;

	if (!(stringp = ast_strdupa(data)))
		return -1;
	
	strsep(&stringp, " "); /* eat the first token, we already know it :P  */
	s = strsep(&stringp, " ");
	id = atoi(s);
	if (!(PGSQLres = find_identifier(id, AST_PGSQL_ID_RESID))) {
		ast_log(LOG_WARNING, "Invalid result identifier %d passed in aPGSQL_clear\n", id);
	} else {
		PQclear(PGSQLres);
		del_identifier(id, AST_PGSQL_ID_RESID);
	}

	return 0;
}

static int aPGSQL_disconnect(struct ast_channel *chan, void *data)
{
	char *s;
	PGconn *PGSQLconn;
	int id;
	char *stringp = NULL;

	if (!(stringp = ast_strdupa(data)))
		return -1;
	
	strsep(&stringp, " "); /* eat the first token, we already know it :P  */
	s = strsep(&stringp, " ");
	id = atoi(s);
	if (!(PGSQLconn = find_identifier(id, AST_PGSQL_ID_CONNID))) {
		ast_log(LOG_WARNING, "Invalid connection identifier %d passed in aPGSQL_disconnect\n", id);
	} else {
		PQfinish(PGSQLconn);
		del_identifier(id, AST_PGSQL_ID_CONNID);
	}
	
	return 0;
}

static int aPGSQL_debug(struct ast_channel *chan, void *data)
{
	ast_log(LOG_WARNING, "Debug : %s\n", (char *)data);
	return 0;
}

static int PGSQL_exec(struct ast_channel *chan, void *data)
{
	struct localuser *u;
	int result;

	if (ast_strlen_zero(data)) {
		ast_log(LOG_WARNING, "APP_PGSQL requires an argument (see manual)\n");
		return -1;
	}

	LOCAL_USER_ADD(u);

	result = 0;

	if (!(strncasecmp("connect", data, strlen("connect")))) {
		result = (aPGSQL_connect(chan, data));
	} else if (!(strncasecmp("query", data, strlen("query")))) {
		result = (aPGSQL_query(chan, data));
	} else if (!(strncasecmp("fetch", data, strlen("fetch")))) {
		result = (aPGSQL_fetch(chan, data));
	} else if (!(strncasecmp("reset", data, strlen("reset")))) {
		result = (aPGSQL_reset(chan, data));
	} else if (!(strncasecmp("clear", data, strlen("clear")))) {
		result = (aPGSQL_clear(chan, data));
	} else if (!(strncasecmp("debug", data, strlen("debug")))) {
		result = (aPGSQL_debug(chan, data));
	} else if (!(strncasecmp("disconnect", data, strlen("disconnect")))) {
		result = (aPGSQL_disconnect(chan, data));
	} else {
		ast_log(LOG_WARNING, "Unknown APP_PGSQL argument : %s\n", (char *)data);
		result = -1;
	}

	LOCAL_USER_REMOVE(u);

	return result;
}

int unload_module(void)
{
	int res = ast_unregister_application(app);
	STANDARD_HANGUP_LOCALUSERS;
	return res;
}

int load_module(void)
{
	struct PGSQLidshead *headp = &PGSQLidshead;
	AST_LIST_HEAD_INIT(headp);
	return ast_register_application(app, PGSQL_exec, synopsis, descrip);
}

char *description(void)
{
	return tdesc;
}

int usecount(void)
{
	int res;
	STANDARD_USECOUNT(res);
	return res;
}

char *key()
{
	return ASTERISK_GPL_KEY;
}