/*       +------------------------------------+
 *       | Inspire Internet Relay Chat Daemon |
 *       +------------------------------------+
 *
 *  InspIRCd is copyright (C) 2002-2004 ChatSpike-Dev.
 *		       E-mail:
 *		<brain@chatspike.net>
 *	   	  <Craig@chatspike.net>
 *     
 * Written by Craig Edwards, Craig McLure, and others.
 * This program is free but copyrighted software; see
 *	    the file COPYING for details.
 *
 * ---------------------------------------------------
 */

using namespace std;

#include <stdio.h>
#include <string>
#include <mysql.h>
#include <pthread.h>
#include "users.h"
#include "channels.h"
#include "modules.h"
#include "helperfuncs.h"
#include "m_sqlv2.h"

/* VERSION 2 API: With nonblocking (threaded) requests */

/* $ModDesc: SQL Service Provider module for all other m_sql* modules */
/* $CompileFlags: `mysql_config --include` */
/* $LinkerFlags: `mysql_config --libs_r` `perl ../mysql_rpath.pl` */

/* THE NONBLOCKING MYSQL API!
 * 
 * MySQL provides no nonblocking (asyncronous) API of its own, and its developers recommend
 * that instead, you should thread your program. This is what i've done here to allow for
 * asyncronous SQL requests via mysql. The way this works is as follows:
 *
 * The module spawns a thread via pthreads, and performs its mysql queries in this thread,
 * using a queue with priorities. There is a mutex on either end which prevents two threads
 * adjusting the queue at the same time, and crashing the ircd. Every 50 milliseconds, the
 * worker thread wakes up, and checks if there is a request at the head of its queue.
 * If there is, it processes this request, blocking the worker thread but leaving the ircd
 * thread to go about its business as usual. During this period, the ircd thread is able
 * to insert futher pending requests into the queue.
 *
 * Once the processing of a request is complete, it is removed from the incoming queue to
 * an outgoing queue, and initialized as a 'response'. The worker thread then signals the
 * ircd thread (via a loopback socket) of the fact a result is available, by sending the
 * connection ID through the connection.
 *
 * The ircd thread then mutexes the queue once more, reads the outbound response off the head
 * of the queue, and sends it on its way to the original calling module.
 *
 * XXX: You might be asking "why doesnt he just send the response from within the worker thread?"
 * The answer to this is simple. The majority of InspIRCd, and in fact most ircd's are not
 * threadsafe. This module is designed to be threadsafe and is careful with its use of threads,
 * however, if we were to call a module's OnRequest even from within a thread which was not the
 * one the module was originally instantiated upon, there is a chance of all hell breaking loose
 * if a module is ever put in a re-enterant state (stack corruption could occur, crashes, data
 * corruption, and worse, so DONT think about it until the day comes when InspIRCd is 100%
 * gauranteed threadsafe!)
 *
 * For a diagram of this system please see http://www.inspircd.org/wiki/Mysql2
 */


class SQLConnection;
class Notifier;

extern InspIRCd* ServerInstance;
typedef std::map<std::string, SQLConnection*> ConnMap;
bool giveup = false;
static Module* SQLModule = NULL;
static Notifier* MessagePipe = NULL;
int QueueFD = -1;


#if !defined(MYSQL_VERSION_ID) || MYSQL_VERSION_ID<32224
#define mysql_field_count mysql_num_fields
#endif

typedef std::deque<SQLresult*> ResultQueue;

class QueryQueue : public classbase
{
private:
	typedef std::deque<SQLrequest> ReqDeque;

	ReqDeque priority;      /* The priority queue */
	ReqDeque normal;	/* The 'normal' queue */
	enum { PRI, NOR, NON } which;   /* Which queue the currently active element is at the front of */

public:
	QueryQueue()
	: which(NON)
	{
	}

	void push(const SQLrequest &q)
	{
		log(DEBUG, "QueryQueue::push(): Adding %s query to queue: %s", ((q.pri) ? "priority" : "non-priority"), q.query.q.c_str());

		if(q.pri)
			priority.push_back(q);
		else
			normal.push_back(q);
	}

	void pop()
	{
		if((which == PRI) && priority.size())
		{
			priority.pop_front();
		}
		else if((which == NOR) && normal.size())
		{
			normal.pop_front();
		}

		/* Reset this */
		which = NON;

		/* Silently do nothing if there was no element to pop() */
	}

	SQLrequest& front()
	{
		switch(which)
		{
			case PRI:
				return priority.front();
			case NOR:
				return normal.front();
			default:
				if(priority.size())
				{
					which = PRI;
					return priority.front();
				}

				if(normal.size())
				{
					which = NOR;
					return normal.front();
				}

				/* This will probably result in a segfault,
				 * but the caller should have checked totalsize()
				 * first so..meh - moron :p
				 */

				return priority.front();
		}
	}

	std::pair<int, int> size()
	{
		return std::make_pair(priority.size(), normal.size());
	}

	int totalsize()
	{
		return priority.size() + normal.size();
	}

	void PurgeModule(Module* mod)
	{
		DoPurgeModule(mod, priority);
		DoPurgeModule(mod, normal);
	}

private:
	void DoPurgeModule(Module* mod, ReqDeque& q)
	{
		for(ReqDeque::iterator iter = q.begin(); iter != q.end(); iter++)
		{
			if(iter->GetSource() == mod)
			{
				if(iter->id == front().id)
				{
					/* It's the currently active query.. :x */
					iter->SetSource(NULL);
				}
				else
				{
					/* It hasn't been executed yet..just remove it */
					iter = q.erase(iter);
				}
			}
		}
	}
};

/* A mutex to wrap around queue accesses */
pthread_mutex_t queue_mutex = PTHREAD_MUTEX_INITIALIZER;

pthread_mutex_t results_mutex = PTHREAD_MUTEX_INITIALIZER;

class MySQLresult : public SQLresult
{
	int currentrow;
	//std::vector<std::map<std::string,std::string> > results;
	std::vector<std::string> colnames;
	std::vector<SQLfieldList> fieldlists;
	SQLfieldMap* fieldmap;
	int rows;
	int cols;
 public:

	MySQLresult(Module* self, Module* to, MYSQL_RES* res, int affected_rows, unsigned int id) : SQLresult(self, to, id), currentrow(0), fieldmap(NULL)
	{
		/* A number of affected rows from from mysql_affected_rows.
		 */
		log(DEBUG,"Created new MySQLresult of non-error type");
		fieldlists.clear();
		rows = 0;
		if (affected_rows >= 1)
		{
			rows = affected_rows;
			fieldlists.resize(rows);
		}
		unsigned int field_count;
		if (res)
		{
			MYSQL_ROW row;
			int n = 0;
			while ((row = mysql_fetch_row(res)))
			{
				if (fieldlists.size() < (unsigned int)rows+1)
				{
					fieldlists.resize(fieldlists.size()+1);
				}
				field_count = 0;
				MYSQL_FIELD *fields = mysql_fetch_fields(res);
				if(mysql_num_fields(res) == 0)
					break;
				if (fields && mysql_num_fields(res))
				{
					colnames.clear();
					while (field_count < mysql_num_fields(res))
					{
						std::string a = (fields[field_count].name ? fields[field_count].name : "");
						std::string b = (row[field_count] ? row[field_count] : "");
						SQLfield sqlf(b, !row[field_count]);
						colnames.push_back(a);
						fieldlists[n].push_back(sqlf); 
						field_count++;
					}
					n++;
				}
				rows++;
			}
			cols = mysql_num_fields(res);
			mysql_free_result(res);
		}
		cols = field_count;
		log(DEBUG, "Created new MySQL result; %d rows, %d columns", rows, cols);
	}

	MySQLresult(Module* self, Module* to, SQLerror e, unsigned int id) : SQLresult(self, to, id), currentrow(0)
	{
		rows = 0;
		cols = 0;
		error = e;
		log(DEBUG,"Created new MySQLresult of error type");
	}

	~MySQLresult()
	{
	}

	virtual int Rows()
	{
		return rows;
	}

	virtual int Cols()
	{
		return cols;
	}

	virtual std::string ColName(int column)
	{
		if (column < (int)colnames.size())
		{
			return colnames[column];
		}
		else
		{
			throw SQLbadColName();
		}
		return "";
	}

	virtual int ColNum(const std::string &column)
	{
		for (unsigned int i = 0; i < colnames.size(); i++)
		{
			if (column == colnames[i])
				return i;
		}
		throw SQLbadColName();
		return 0;
	}

	virtual SQLfield GetValue(int row, int column)
	{
		if ((row >= 0) && (row < rows) && (column >= 0) && (column < cols))
		{
			return fieldlists[row][column];
		}

		log(DEBUG,"Danger will robinson, we don't have row %d, column %d!", row, column);
		throw SQLbadColName();

		/* XXX: We never actually get here because of the throw */
		return SQLfield("",true);
	}

	virtual SQLfieldList& GetRow()
	{
		return fieldlists[currentrow];
	}

	virtual SQLfieldMap& GetRowMap()
	{
		fieldmap = new SQLfieldMap();
		
		for (int i = 0; i < cols; i++)
		{
			fieldmap->insert(std::make_pair(colnames[cols],GetValue(currentrow, i)));
		}
		currentrow++;

		return *fieldmap;
	}

	virtual SQLfieldList* GetRowPtr()
	{
		return &fieldlists[currentrow++];
	}

	virtual SQLfieldMap* GetRowMapPtr()
	{
		fieldmap = new SQLfieldMap();

		for (int i = 0; i < cols; i++)
		{
			fieldmap->insert(std::make_pair(colnames[cols],GetValue(currentrow, i)));
		}
		currentrow++;

		return fieldmap;
	}

	virtual void Free(SQLfieldMap* fm)
	{
		delete fm;
	}

	virtual void Free(SQLfieldList* fl)
	{
		/* XXX: Yes, this is SUPPOSED to do nothing, we
		 * dont want to free our fieldlist until we
		 * destruct the object. Unlike the pgsql module,
		 * we only have the one.
		 */
	}
};

class SQLConnection;

void NotifyMainThread(SQLConnection* connection_with_new_result);

class SQLConnection : public classbase
{
 protected:

	MYSQL connection;
	MYSQL_RES *res;
	MYSQL_ROW row;
	std::string host;
	std::string user;
	std::string pass;
	std::string db;
	std::map<std::string,std::string> thisrow;
	bool Enabled;
	std::string id;

 public:

	QueryQueue queue;
	ResultQueue rq;

	// This constructor creates an SQLConnection object with the given credentials, and creates the underlying
	// MYSQL struct, but does not connect yet.
	SQLConnection(std::string thishost, std::string thisuser, std::string thispass, std::string thisdb, const std::string &myid)
	{
		this->Enabled = true;
		this->host = thishost;
		this->user = thisuser;
		this->pass = thispass;
		this->db = thisdb;
		this->id = myid;
	}

	// This method connects to the database using the credentials supplied to the constructor, and returns
	// true upon success.
	bool Connect()
	{
		unsigned int timeout = 1;
		mysql_init(&connection);
		mysql_options(&connection,MYSQL_OPT_CONNECT_TIMEOUT,(char*)&timeout);
		return mysql_real_connect(&connection, host.c_str(), user.c_str(), pass.c_str(), db.c_str(), 0, NULL, 0);
	}

	void DoLeadingQuery()
	{
		if (!CheckConnection())
			return;

		/* Parse the command string and dispatch it to mysql */
		SQLrequest& req = queue.front();
		log(DEBUG,"DO QUERY: %s",req.query.q.c_str());

		/* Pointer to the buffer we screw around with substitution in */
		char* query;

		/* Pointer to the current end of query, where we append new stuff */
		char* queryend;

		/* Total length of the unescaped parameters */
		unsigned long paramlen;

		/* Total length of query, used for binary-safety in mysql_real_query */
		unsigned long querylength = 0;

		paramlen = 0;

		for(ParamL::iterator i = req.query.p.begin(); i != req.query.p.end(); i++)
		{
			paramlen += i->size();
		}

		/* To avoid a lot of allocations, allocate enough memory for the biggest the escaped query could possibly be.
		 * sizeofquery + (totalparamlength*2) + 1
		 *
		 * The +1 is for null-terminating the string for mysql_real_escape_string
		 */

		query = new char[req.query.q.length() + (paramlen*2)];
		queryend = query;

		/* Okay, now we have a buffer large enough we need to start copying the query into it and escaping and substituting
		 * the parameters into it...
		 */

		for(unsigned long i = 0; i < req.query.q.length(); i++)
		{
			if(req.query.q[i] == '?')
			{
				/* We found a place to substitute..what fun.
				 * use mysql calls to escape and write the
				 * escaped string onto the end of our query buffer,
				 * then we "just" need to make sure queryend is
				 * pointing at the right place.
				 */
				if(req.query.p.size())
				{
					unsigned long len = mysql_real_escape_string(&connection, queryend, req.query.p.front().c_str(), req.query.p.front().length());

					queryend += len;
					req.query.p.pop_front();
				}
				else
				{
					log(DEBUG, "Found a substitution location but no parameter to substitute :|");
					break;
				}
			}
			else
			{
				*queryend = req.query.q[i];
				queryend++;
			}
			querylength++;
		}

		*queryend = 0;

		log(DEBUG, "Attempting to dispatch query: %s", query);

		pthread_mutex_lock(&queue_mutex);
		req.query.q = query;
		pthread_mutex_unlock(&queue_mutex);

		if (!mysql_real_query(&connection, req.query.q.data(), req.query.q.length()))
		{
			/* Successfull query */
			res = mysql_use_result(&connection);
			unsigned long rows = mysql_affected_rows(&connection);
			MySQLresult* r = new MySQLresult(SQLModule, req.GetSource(), res, rows, req.id);
			r->dbid = this->GetID();
			r->query = req.query.q;
			/* Put this new result onto the results queue.
			 * XXX: Remember to mutex the queue!
			 */
			pthread_mutex_lock(&results_mutex);
			rq.push_back(r);
			pthread_mutex_unlock(&results_mutex);
		}
		else
		{
			/* XXX: See /usr/include/mysql/mysqld_error.h for a list of
			 * possible error numbers and error messages */
			log(DEBUG,"SQL ERROR: %s",mysql_error(&connection));
			SQLerror e((SQLerrorNum)mysql_errno(&connection), mysql_error(&connection));
			MySQLresult* r = new MySQLresult(SQLModule, req.GetSource(), e, req.id);
			r->dbid = this->GetID();
			r->query = req.query.q;

			pthread_mutex_lock(&results_mutex);
			rq.push_back(r);
			pthread_mutex_unlock(&results_mutex);
		}

		/* Now signal the main thread that we've got a result to process.
		 * Pass them this connection id as what to examine
		 */

		NotifyMainThread(this);
	}

	bool ConnectionLost()
	{
		if (&connection) {
			return (mysql_ping(&connection) != 0);
		}
		else return false;
	}

	bool CheckConnection()
	{
		if (ConnectionLost()) {
			return Connect();
		}
		else return true;
	}

	std::string GetError()
	{
		return mysql_error(&connection);
	}

	const std::string& GetID()
	{
		return id;
	}

	std::string GetHost()
	{
		return host;
	}

	void SetEnable(bool Enable)
	{
		Enabled = Enable;
	}

	bool IsEnabled()
	{
		return Enabled;
	}

};

ConnMap Connections;

void ConnectDatabases(Server* Srv)
{
	for (ConnMap::iterator i = Connections.begin(); i != Connections.end(); i++)
	{
		i->second->SetEnable(true);
		if (i->second->Connect())
		{
			Srv->Log(DEFAULT,"SQL: Successfully connected database "+i->second->GetHost());
		}
		else
		{
			Srv->Log(DEFAULT,"SQL: Failed to connect database "+i->second->GetHost()+": Error: "+i->second->GetError());
			i->second->SetEnable(false);
		}
	}
}


void LoadDatabases(ConfigReader* ThisConf, Server* Srv)
{
	Srv->Log(DEFAULT,"SQL: Loading database settings");
	Connections.clear();
	Srv->Log(DEBUG,"Cleared connections");
	for (int j =0; j < ThisConf->Enumerate("database"); j++)
	{
		std::string db = ThisConf->ReadValue("database","name",j);
		std::string user = ThisConf->ReadValue("database","username",j);
		std::string pass = ThisConf->ReadValue("database","password",j);
		std::string host = ThisConf->ReadValue("database","hostname",j);
		std::string id = ThisConf->ReadValue("database","id",j);
		Srv->Log(DEBUG,"Read database settings");
		if ((db != "") && (host != "") && (user != "") && (id != "") && (pass != ""))
		{
			SQLConnection* ThisSQL = new SQLConnection(host,user,pass,db,id);
			Srv->Log(DEFAULT,"Loaded database: "+ThisSQL->GetHost());
			Connections[id] = ThisSQL;
			Srv->Log(DEBUG,"Pushed back connection");
		}
	}
	ConnectDatabases(Srv);
}

void NotifyMainThread(SQLConnection* connection_with_new_result)
{
	/* Here we write() to the socket the main thread has open
	 * and we connect()ed back to before our thread became active.
	 * The main thread is using a nonblocking socket tied into
	 * the socket engine, so they wont block and they'll receive
	 * nearly instant notification. Because we're in a seperate
	 * thread, we can just use standard connect(), and we can
	 * block if we like. We just send the connection id of the
	 * connection back.
	 */
	log(DEBUG,"Notify of result on connection: %s",connection_with_new_result->GetID().c_str());
	if (send(QueueFD, connection_with_new_result->GetID().c_str(), connection_with_new_result->GetID().length()+1, 0) < 1) // add one for null terminator
	{
		log(DEBUG,"Error writing to QueueFD: %s",strerror(errno));
	}
	log(DEBUG,"Sent it on its way via fd=%d",QueueFD);
}

void* DispatcherThread(void* arg);

class Notifier : public InspSocket
{
	sockaddr_in sock_us;
	socklen_t uslen;
	Server* Srv;

 public:

	/* Create a socket on a random port. Let the tcp stack allocate us an available port */
	Notifier(Server* S) : InspSocket("127.0.0.1", 0, true, 3000), Srv(S)
	{
		uslen = sizeof(sock_us);
		if (getsockname(this->fd,(sockaddr*)&sock_us,&uslen))
		{
			throw ModuleException("Could not create random listening port on localhost");
		}
	}

	Notifier(int newfd, char* ip, Server* S) : InspSocket(newfd, ip), Srv(S)
	{
		log(DEBUG,"Constructor of new socket");
	}

	/* Using getsockname and ntohs, we can determine which port number we were allocated */
	int GetPort()
	{
		return ntohs(sock_us.sin_port);
	}

	virtual int OnIncomingConnection(int newsock, char* ip)
	{
		log(DEBUG,"Inbound connection on fd %d!",newsock);
		Notifier* n = new Notifier(newsock, ip, Srv);
		Srv->AddSocket(n);
		return true;
	}

	virtual bool OnDataReady()
	{
		log(DEBUG,"Inbound data!");
		char* data = this->Read();
		ConnMap::iterator iter;

		if (data && *data)
		{
			log(DEBUG,"Looking for connection %s",data);
			/* We expect to be sent a null terminated string */
			if((iter = Connections.find(data)) != Connections.end())
			{
				log(DEBUG,"Found it!");

				/* Lock the mutex, send back the data */
				pthread_mutex_lock(&results_mutex);
				ResultQueue::iterator n = iter->second->rq.begin();
				(*n)->Send();
				iter->second->rq.pop_front();
				pthread_mutex_unlock(&results_mutex);
				return true;
			}
		}

		return false;
	}
};

class ModuleSQL : public Module
{
 public:
	Server *Srv;
	ConfigReader *Conf;
	pthread_t Dispatcher;
	int currid;

	void Implements(char* List)
	{
		List[I_OnRehash] = List[I_OnRequest] = 1;
	}

	unsigned long NewID()
	{
		if (currid+1 == 0)
			currid++;
		return ++currid;
	}

	char* OnRequest(Request* request)
	{
		if(strcmp(SQLREQID, request->GetData()) == 0)
		{
			SQLrequest* req = (SQLrequest*)request;

			/* XXX: Lock */
			pthread_mutex_lock(&queue_mutex);

			ConnMap::iterator iter;

			char* returnval = NULL;

			log(DEBUG, "Got query: '%s' with %d replacement parameters on id '%s'", req->query.q.c_str(), req->query.p.size(), req->dbid.c_str());

			if((iter = Connections.find(req->dbid)) != Connections.end())
			{
				iter->second->queue.push(*req);
				req->id = NewID();
				returnval = SQLSUCCESS;
			}
			else
			{
				req->error.Id(BAD_DBID);
			}

			pthread_mutex_unlock(&queue_mutex);
			/* XXX: Unlock */

			return returnval;
		}

		log(DEBUG, "Got unsupported API version string: %s", request->GetData());

		return NULL;
	}

	ModuleSQL(Server* Me)
		: Module::Module(Me)
	{
		Srv = Me;
		Conf = new ConfigReader();
		currid = 0;
		SQLModule = this;

		MessagePipe = new Notifier(Srv);
		Srv->AddSocket(MessagePipe);
		log(DEBUG,"Bound notifier to 127.0.0.1:%d",MessagePipe->GetPort());
		
		pthread_attr_t attribs;
		pthread_attr_init(&attribs);
		pthread_attr_setdetachstate(&attribs, PTHREAD_CREATE_DETACHED);
		if (pthread_create(&this->Dispatcher, &attribs, DispatcherThread, (void *)this) != 0)
		{
			throw ModuleException("m_mysql: Failed to create dispatcher thread: " + std::string(strerror(errno)));
		}
		Srv->PublishFeature("SQL", this);
		Srv->PublishFeature("MySQL", this);
	}
	
	virtual ~ModuleSQL()
	{
		DELETE(Conf);
	}
	
	virtual void OnRehash(const std::string &parameter)
	{
		/* TODO: set rehash bool here, which makes the dispatcher thread rehash at next opportunity */
	}
	
	virtual Version GetVersion()
	{
		return Version(1,1,0,0,VF_VENDOR|VF_SERVICEPROVIDER);
	}
	
};

void* DispatcherThread(void* arg)
{
	log(DEBUG,"Starting Dispatcher thread, mysql version %d",mysql_get_client_version());
	ModuleSQL* thismodule = (ModuleSQL*)arg;
	LoadDatabases(thismodule->Conf, thismodule->Srv);

	/* Connect back to the Notifier */

	if ((QueueFD = socket(AF_INET, SOCK_STREAM, 0)) == -1)
	{
		/* crap, we're out of sockets... */
		log(DEBUG,"QueueFD cant be created");
		return NULL;
	}

	log(DEBUG,"Initialize QueueFD to %d",QueueFD);

	sockaddr_in addr;
	in_addr ia;
	inet_aton("127.0.0.1", &ia);
	addr.sin_family = AF_INET;
	addr.sin_addr = ia;
	addr.sin_port = htons(MessagePipe->GetPort());

	if (connect(QueueFD, (sockaddr*)&addr,sizeof(addr)) == -1)
	{
		/* wtf, we cant connect to it, but we just created it! */
		log(DEBUG,"QueueFD cant connect!");
		return NULL;
	}

	log(DEBUG,"Connect QUEUE FD");

	while (!giveup)
	{
		SQLConnection* conn = NULL;
		/* XXX: Lock here for safety */
		pthread_mutex_lock(&queue_mutex);
		for (ConnMap::iterator i = Connections.begin(); i != Connections.end(); i++)
		{
			if (i->second->queue.totalsize())
			{
				conn = i->second;
				break;
			}
		}
		pthread_mutex_unlock(&queue_mutex);
		/* XXX: Unlock */

		/* Theres an item! */
		if (conn)
		{
			log(DEBUG,"Process Leading query");
			conn->DoLeadingQuery();

			/* XXX: Lock */
			pthread_mutex_lock(&queue_mutex);
			conn->queue.pop();
			pthread_mutex_unlock(&queue_mutex);
			/* XXX: Unlock */
		}

		usleep(50);
	}

	return NULL;
}


// stuff down here is the module-factory stuff. For basic modules you can ignore this.

class ModuleSQLFactory : public ModuleFactory
{
 public:
	ModuleSQLFactory()
	{
	}
	
	~ModuleSQLFactory()
	{
	}
	
	virtual Module * CreateModule(Server* Me)
	{
		return new ModuleSQL(Me);
	}
	
};


extern "C" void * init_module( void )
{
	return new ModuleSQLFactory;
}