/**
 * collectd - src/apache.c
 * Copyright (C) 2006-2010  Florian octo Forster
 * Copyright (C) 2007       Florent EppO Monbillard
 * Copyright (C) 2009       Amit Gupta
 *
 * 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; only version 2 of the License is applicable.
 *
 * 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.,
 * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
 *
 * Authors:
 *   Florian octo Forster <octo at verplant.org>
 *   Florent EppO Monbillard <eppo at darox.net>
 *   - connections/lighttpd extension
 *   Amit Gupta <amit.gupta221 at gmail.com>
 **/

#include "collectd.h"
#include "common.h"
#include "plugin.h"
#include "configfile.h"

#include <curl/curl.h>

enum server_enum
{
	APACHE = 0,
	LIGHTTPD
};

struct apache_s
{
	int server_type;
	char *name;
	char *host;
	char *url;
	char *user;
	char *pass;
	int   verify_peer;
	int   verify_host;
	char *cacert;
	char *server; /* user specific server type */
	char *apache_buffer;
	char apache_curl_error[CURL_ERROR_SIZE];
	size_t apache_buffer_size;
	size_t apache_buffer_fill;
	CURL *curl;
}; /* apache_s */

typedef struct apache_s apache_t;

/* TODO: Remove this prototype */
static int apache_read_host (user_data_t *user_data);

static void apache_free (apache_t *st)
{
	if (st == NULL)
		return;

	sfree (st->name);
	sfree (st->host);
	sfree (st->url);
	sfree (st->user);
	sfree (st->pass);
	sfree (st->cacert);
	sfree (st->server);
	sfree (st->apache_buffer);
	if (st->curl) {
		curl_easy_cleanup(st->curl);
		st->curl = NULL;
	}
} /* apache_free */

static size_t apache_curl_callback (void *buf, size_t size, size_t nmemb,
		void *user_data)
{
	size_t len = size * nmemb;
	apache_t *st;

	st = user_data;
	if (st == NULL)
	{
		ERROR ("apache plugin: apache_curl_callback: "
				"user_data pointer is NULL.");
		return (0);
	}

	if (len <= 0)
		return (len);

	if ((st->apache_buffer_fill + len) >= st->apache_buffer_size)
	{
		char *temp;

		temp = (char *) realloc (st->apache_buffer,
				st->apache_buffer_fill + len + 1);
		if (temp == NULL)
		{
			ERROR ("apache plugin: realloc failed.");
			return (0);
		}
		st->apache_buffer = temp;
		st->apache_buffer_size = st->apache_buffer_fill + len + 1;
	}

	memcpy (st->apache_buffer + st->apache_buffer_fill, (char *) buf, len);
	st->apache_buffer_fill += len;
	st->apache_buffer[st->apache_buffer_fill] = 0;

	return (len);
} /* int apache_curl_callback */

static size_t apache_header_callback (void *buf, size_t size, size_t nmemb,
		void *user_data)
{
	size_t len = size * nmemb;
	apache_t *st;

	st = user_data;
	if (st == NULL)
	{
		ERROR ("apache plugin: apache_header_callback: "
				"user_data pointer is NULL.");
		return (0);
	}

	if (len <= 0)
		return (len);

	/* look for the Server header */
	if (strncasecmp (buf, "Server: ", strlen ("Server: ")) != 0)
		return (len);

	if (strstr (buf, "Apache") != NULL)
		st->server_type = APACHE;
	else if (strstr (buf, "lighttpd") != NULL)
		st->server_type = LIGHTTPD;
	else if (strstr (buf, "IBM_HTTP_Server") != NULL)
		st->server_type = APACHE;
	else
	{
		const char *hdr = buf;

		hdr += strlen ("Server: ");
		NOTICE ("apache plugin: Unknown server software: %s", hdr);
	}

	return (len);
} /* apache_header_callback */

/* Configuration handling functiions
 * <Plugin apache>
 *   <Instance "instance_name">
 *     URL ...
 *   </Instance>
 *   URL ...
 * </Plugin>
 */
static int config_set_string (char **ret_string, /* {{{ */
				    oconfig_item_t *ci)
{
	char *string;

	if ((ci->values_num != 1)
			|| (ci->values[0].type != OCONFIG_TYPE_STRING))
	{
		WARNING ("apache plugin: The `%s' config option "
				"needs exactly one string argument.", ci->key);
		return (-1);
	}

	string = strdup (ci->values[0].value.string);
	if (string == NULL)
	{
		ERROR ("apache plugin: strdup failed.");
		return (-1);
	}

	if (*ret_string != NULL)
		free (*ret_string);
	*ret_string = string;

	return (0);
} /* }}} int config_set_string */

static int config_set_boolean (int *ret_boolean, /* {{{ */
				    oconfig_item_t *ci)
{
	if ((ci->values_num != 1)
			|| ((ci->values[0].type != OCONFIG_TYPE_BOOLEAN)
				&& (ci->values[0].type != OCONFIG_TYPE_STRING)))
	{
		WARNING ("apache plugin: The `%s' config option "
				"needs exactly one boolean argument.", ci->key);
		return (-1);
	}

	if (ci->values[0].type == OCONFIG_TYPE_BOOLEAN)
	{
		if (ci->values[0].value.boolean)
			*ret_boolean = 1;
		else
			*ret_boolean = 0;
	}
	else /* if (ci->values[0].type != OCONFIG_TYPE_STRING) */
	{
		char *string = ci->values[0].value.string;
		if (IS_TRUE (string))
			*ret_boolean = 1;
		else if (IS_FALSE (string))
			*ret_boolean = 0;
		else
		{
			ERROR ("apache plugin: Cannot parse string "
					"as boolean value: %s", string);
			return (-1);
		}
	}

	return (0);
} /* }}} int config_set_boolean */

static int config_add (oconfig_item_t *ci)
{
	apache_t *st;
	int i;
	int status;

	if ((ci->values_num != 1)
		|| (ci->values[0].type != OCONFIG_TYPE_STRING))
	{
		WARNING ("apache plugin: The `%s' config option "
			"needs exactly one string argument.", ci->key);
		return (-1);
	}

	st = (apache_t *) malloc (sizeof (*st));
	if (st == NULL)
	{
		ERROR ("apache plugin: malloc failed.");
		return (-1);
	}

	memset (st, 0, sizeof (*st));

	status = config_set_string (&st->name, ci);
	if (status != 0)
	{
		sfree (st);
		return (status);
	}
	assert (st->name != NULL);

	for (i = 0; i < ci->children_num; i++)
	{
		oconfig_item_t *child = ci->children + i;

		if (strcasecmp ("URL", child->key) == 0)
			status = config_set_string (&st->url, child);
		else if (strcasecmp ("Host", child->key) == 0)
			status = config_set_string (&st->host, child);
		else if (strcasecmp ("User", child->key) == 0)
			status = config_set_string (&st->user, child);
		else if (strcasecmp ("Password", child->key) == 0)
			status = config_set_string (&st->pass, child);
		else if (strcasecmp ("VerifyPeer", child->key) == 0)
			status = config_set_boolean (&st->verify_peer, child);
		else if (strcasecmp ("VerifyHost", child->key) == 0)
			status = config_set_boolean (&st->verify_host, child);
		else if (strcasecmp ("CACert", child->key) == 0)
			status = config_set_string (&st->cacert, child);
		else if (strcasecmp ("Server", child->key) == 0)
			status = config_set_string (&st->server, child);
		else
		{
			WARNING ("apache plugin: Option `%s' not allowed here.",
					child->key);
			status = -1;
		}

		if (status != 0)
			break;
	}

	/* Check if struct is complete.. */
	if ((status == 0) && (st->url == NULL))
	{
		ERROR ("apache plugin: Instance `%s': "
				"No URL has been configured.",
				st->name);
		status = -1;
	}

	if (status == 0)
	{
		user_data_t ud;
		char callback_name[3*DATA_MAX_NAME_LEN];

		memset (&ud, 0, sizeof (ud));
		ud.data = st;
		ud.free_func = (void *) apache_free;

		memset (callback_name, 0, sizeof (callback_name));
		ssnprintf (callback_name, sizeof (callback_name),
				"apache/%s/%s",
				(st->host != NULL) ? st->host : hostname_g,
				(st->name != NULL) ? st->name : "default"),

		status = plugin_register_complex_read (/* group = */ NULL,
				/* name      = */ callback_name,
				/* callback  = */ apache_read_host,
				/* interval  = */ NULL,
				/* user_data = */ &ud);
	}

	if (status != 0)
	{
		apache_free(st);
		return (-1);
	}

	return (0);
} /* int config_add */

static int config (oconfig_item_t *ci)
{
	int status = 0;
	int i;

	for (i = 0; i < ci->children_num; i++)
	{
		oconfig_item_t *child = ci->children + i;

		if (strcasecmp ("Instance", child->key) == 0)
			config_add (child);
		else
			WARNING ("apache plugin: The configuration option "
					"\"%s\" is not allowed here. Did you "
					"forget to add an <Instance /> block "
					"around the configuration?",
					child->key);
	} /* for (ci->children) */

	return (status);
} /* int config */

/* initialize curl for each host */
static int init_host (apache_t *st) /* {{{ */
{
	static char credentials[1024];

	assert (st->url != NULL);
	/* (Assured by `config_add') */

	if (st->curl != NULL)
	{
		curl_easy_cleanup (st->curl);
		st->curl = NULL;
	}

	if ((st->curl = curl_easy_init ()) == NULL)
	{
		ERROR ("apache plugin: init_host: `curl_easy_init' failed.");
		return (-1);
	}

	curl_easy_setopt (st->curl, CURLOPT_NOSIGNAL, 1L);
	curl_easy_setopt (st->curl, CURLOPT_WRITEFUNCTION, apache_curl_callback);
	curl_easy_setopt (st->curl, CURLOPT_WRITEDATA, st);

	/* not set as yet if the user specified string doesn't match apache or
	 * lighttpd, then ignore it. Headers will be parsed to find out the
	 * server type */
	st->server_type = -1;

	if (st->server != NULL)
	{
		if (strcasecmp(st->server, "apache") == 0)
			st->server_type = APACHE;
		else if (strcasecmp(st->server, "lighttpd") == 0)
			st->server_type = LIGHTTPD;
		else if (strcasecmp(st->server, "ibm_http_server") == 0)
			st->server_type = APACHE;
		else
			WARNING ("apache plugin: Unknown `Server' setting: %s",
					st->server);
	}

	/* if not found register a header callback to determine the server_type */
	if (st->server_type == -1)
	{
		curl_easy_setopt (st->curl, CURLOPT_HEADERFUNCTION, apache_header_callback);
		curl_easy_setopt (st->curl, CURLOPT_WRITEHEADER, st);
	}

	curl_easy_setopt (st->curl, CURLOPT_USERAGENT, PACKAGE_NAME"/"PACKAGE_VERSION);
	curl_easy_setopt (st->curl, CURLOPT_ERRORBUFFER, st->apache_curl_error);

	if (st->user != NULL)
	{
		int status;

		status = ssnprintf (credentials, sizeof (credentials), "%s:%s",
				st->user, (st->pass == NULL) ? "" : st->pass);
		if ((status < 0) || ((size_t) status >= sizeof (credentials)))
		{
			ERROR ("apache plugin: init_host: Returning an error "
					"because the credentials have been "
					"truncated.");
			curl_easy_cleanup (st->curl);
			st->curl = NULL;
			return (-1);
		}

		curl_easy_setopt (st->curl, CURLOPT_USERPWD, credentials);
	}

	curl_easy_setopt (st->curl, CURLOPT_URL, st->url);
	curl_easy_setopt (st->curl, CURLOPT_FOLLOWLOCATION, 1L);
	curl_easy_setopt (st->curl, CURLOPT_MAXREDIRS, 50L);

	if (st->verify_peer != 0)
	{
		curl_easy_setopt (st->curl, CURLOPT_SSL_VERIFYPEER, 1L);
	}
	else
	{
		curl_easy_setopt (st->curl, CURLOPT_SSL_VERIFYPEER, 0L);
	}

	if (st->verify_host != 0)
	{
		curl_easy_setopt (st->curl, CURLOPT_SSL_VERIFYHOST, 2L);
	}
	else
	{
		curl_easy_setopt (st->curl, CURLOPT_SSL_VERIFYHOST, 0L);
	}

	if (st->cacert != NULL)
	{
		curl_easy_setopt (st->curl, CURLOPT_CAINFO, st->cacert);
	}

	return (0);
} /* }}} int init_host */

static void submit_value (const char *type, const char *type_instance,
		value_t value, apache_t *st)
{
	value_list_t vl = VALUE_LIST_INIT;

	vl.values = &value;
	vl.values_len = 1;

	sstrncpy (vl.host, (st->host != NULL) ? st->host : hostname_g,
			sizeof (vl.host));

	sstrncpy (vl.plugin, "apache", sizeof (vl.plugin));
	if (st->name != NULL)
		sstrncpy (vl.plugin_instance, st->name,
				sizeof (vl.plugin_instance));

	sstrncpy (vl.type, type, sizeof (vl.type));
	if (type_instance != NULL)
		sstrncpy (vl.type_instance, type_instance,
				sizeof (vl.type_instance));

	plugin_dispatch_values (&vl);
} /* void submit_value */

static void submit_derive (const char *type, const char *type_instance,
		derive_t c, apache_t *st)
{
	value_t v;
	v.derive = c;
	submit_value (type, type_instance, v, st);
} /* void submit_derive */

static void submit_gauge (const char *type, const char *type_instance,
		gauge_t g, apache_t *st)
{
	value_t v;
	v.gauge = g;
	submit_value (type, type_instance, v, st);
} /* void submit_gauge */

static void submit_scoreboard (char *buf, apache_t *st)
{
	/*
	 * Scoreboard Key:
	 * "_" Waiting for Connection, "S" Starting up,
	 * "R" Reading Request for apache and read-POST for lighttpd,
	 * "W" Sending Reply, "K" Keepalive (read), "D" DNS Lookup,
	 * "C" Closing connection, "L" Logging, "G" Gracefully finishing,
	 * "I" Idle cleanup of worker, "." Open slot with no current process
	 * Lighttpd specific legends -
	 * "E" hard error, "." connect, "h" handle-request,
	 * "q" request-start, "Q" request-end, "s" response-start
	 * "S" response-end, "r" read
	 */
	long long open      = 0LL;
	long long waiting   = 0LL;
	long long starting  = 0LL;
	long long reading   = 0LL;
	long long sending   = 0LL;
	long long keepalive = 0LL;
	long long dnslookup = 0LL;
	long long closing   = 0LL;
	long long logging   = 0LL;
	long long finishing = 0LL;
	long long idle_cleanup = 0LL;

	/* lighttpd specific */
	long long hard_error     = 0LL;
	long long lighttpd_read  = 0LL;
	long long handle_request = 0LL;
	long long request_start  = 0LL;
	long long request_end    = 0LL;
	long long response_start = 0LL;
	long long response_end   = 0LL;

	int i;
	for (i = 0; buf[i] != '\0'; i++)
	{
		if (buf[i] == '.') open++;
		else if (buf[i] == '_') waiting++;
		else if (buf[i] == 'S') starting++;
		else if (buf[i] == 'R') reading++;
		else if (buf[i] == 'W') sending++;
		else if (buf[i] == 'K') keepalive++;
		else if (buf[i] == 'D') dnslookup++;
		else if (buf[i] == 'C') closing++;
		else if (buf[i] == 'L') logging++;
		else if (buf[i] == 'G') finishing++;
		else if (buf[i] == 'I') idle_cleanup++;
		else if (buf[i] == 'r') lighttpd_read++;
		else if (buf[i] == 'h') handle_request++;
		else if (buf[i] == 'E') hard_error++;
		else if (buf[i] == 'q') request_start++;
		else if (buf[i] == 'Q') request_end++;
		else if (buf[i] == 's') response_start++;
		else if (buf[i] == 'S') response_end++;
	}

	if (st->server_type == APACHE)
	{
		submit_gauge ("apache_scoreboard", "open"     , open, st);
		submit_gauge ("apache_scoreboard", "waiting"  , waiting, st);
		submit_gauge ("apache_scoreboard", "starting" , starting, st);
		submit_gauge ("apache_scoreboard", "reading"  , reading, st);
		submit_gauge ("apache_scoreboard", "sending"  , sending, st);
		submit_gauge ("apache_scoreboard", "keepalive", keepalive, st);
		submit_gauge ("apache_scoreboard", "dnslookup", dnslookup, st);
		submit_gauge ("apache_scoreboard", "closing"  , closing, st);
		submit_gauge ("apache_scoreboard", "logging"  , logging, st);
		submit_gauge ("apache_scoreboard", "finishing", finishing, st);
		submit_gauge ("apache_scoreboard", "idle_cleanup", idle_cleanup, st);
	}
	else
	{
		submit_gauge ("apache_scoreboard", "connect"       , open, st);
		submit_gauge ("apache_scoreboard", "close"         , closing, st);
		submit_gauge ("apache_scoreboard", "hard_error"    , hard_error, st);
		submit_gauge ("apache_scoreboard", "read"          , lighttpd_read, st);
		submit_gauge ("apache_scoreboard", "read_post"     , reading, st);
		submit_gauge ("apache_scoreboard", "write"         , sending, st);
		submit_gauge ("apache_scoreboard", "handle_request", handle_request, st);
		submit_gauge ("apache_scoreboard", "request_start" , request_start, st);
		submit_gauge ("apache_scoreboard", "request_end"   , request_end, st);
		submit_gauge ("apache_scoreboard", "response_start", response_start, st);
		submit_gauge ("apache_scoreboard", "response_end"  , response_end, st);
	}
}

static int apache_read_host (user_data_t *user_data) /* {{{ */
{
	int i;

	char *ptr;
	char *saveptr;
	char *lines[16];
	int   lines_num = 0;

	char *fields[4];
	int   fields_num;

	apache_t *st;

	st = user_data->data;

	assert (st->url != NULL);
	/* (Assured by `config_add') */

	if (st->curl == NULL)
	{
		int status;

		status = init_host (st);
		if (status != 0)
			return (-1);
	}
	assert (st->curl != NULL);

	st->apache_buffer_fill = 0;
	if (curl_easy_perform (st->curl) != CURLE_OK)
	{
		ERROR ("apache: curl_easy_perform failed: %s",
				st->apache_curl_error);
		return (-1);
	}

	/* fallback - server_type to apache if not set at this time */
	if (st->server_type == -1)
	{
		WARNING ("apache plugin: Unable to determine server software "
				"automatically. Will assume Apache.");
		st->server_type = APACHE;
	}

	ptr = st->apache_buffer;
	saveptr = NULL;
	while ((lines[lines_num] = strtok_r (ptr, "\n\r", &saveptr)) != NULL)
	{
		ptr = NULL;
		lines_num++;

		if (lines_num >= 16)
			break;
	}

	for (i = 0; i < lines_num; i++)
	{
		fields_num = strsplit (lines[i], fields, 4);

		if (fields_num == 3)
		{
			if ((strcmp (fields[0], "Total") == 0)
					&& (strcmp (fields[1], "Accesses:") == 0))
				submit_derive ("apache_requests", "",
						atoll (fields[2]), st);
			else if ((strcmp (fields[0], "Total") == 0)
					&& (strcmp (fields[1], "kBytes:") == 0))
				submit_derive ("apache_bytes", "",
						1024LL * atoll (fields[2]), st);
		}
		else if (fields_num == 2)
		{
			if (strcmp (fields[0], "Scoreboard:") == 0)
				submit_scoreboard (fields[1], st);
			else if ((strcmp (fields[0], "BusyServers:") == 0) /* Apache 1.* */
					|| (strcmp (fields[0], "BusyWorkers:") == 0) /* Apache 2.* */)
				submit_gauge ("apache_connections", NULL, atol (fields[1]), st);
			else if ((strcmp (fields[0], "IdleServers:") == 0) /* Apache 1.x */
					|| (strcmp (fields[0], "IdleWorkers:") == 0) /* Apache 2.x */)
				submit_gauge ("apache_idle_workers", NULL, atol (fields[1]), st);
		}
	}

	st->apache_buffer_fill = 0;

	return (0);
} /* }}} int apache_read_host */

void module_register (void)
{
	plugin_register_complex_config ("apache", config);
} /* void module_register */

/* vim: set sw=8 noet fdm=marker : */
