/** @file
	Parser MySQL driver.

	Copyright(c) 2001, 2003 ArtLebedev Group (http://www.artlebedev.com)

	Author: Alexandr Petrosian <paf@design.ru> (http://paf.design.ru)

	2001.07.30 using MySQL 3.23.22b

	2001.11.06 numrows on "HP-UX istok1 B.11.00 A 9000/869 448594332 two-user license"
		3.23.42 & 4.0.0.alfa never worked, both subst & .sl version returned 0
*/
static const char *RCSId="$Id: parser3mysql.C,v 1.26 2004/12/23 16:54:52 paf Exp $"; 

#include "config_includes.h"

#include "pa_sql_driver.h"

#define NO_CLIENT_LONG_LONG
#include "mysql.h"
#include "ltdl.h"

#define MAX_STRING 0x400
#define MAX_NUMBER 20

#if _MSC_VER
#	define snprintf _snprintf
#	define strcasecmp _stricmp
#endif

static char *lsplit(char *string, char delim) {
    if(string) {
		char *v=strchr(string, delim);
		if(v) {
			*v=0;
			return v+1;
		}
    }
    return 0;
}

static char *lsplit(char **string_ref, char delim) {
    char *result=*string_ref;
	char *next=lsplit(*string_ref, delim);
    *string_ref=next;
    return result;
}

static char* rsplit(char* string, char delim) {
    if(string) {
		char* v=strrchr(string, delim); 
		if(v) {
			*v=0;
			return v+1;
		}
    }
    return NULL;	
}

static void toupper_str(char *out, const char *in, size_t size) {
	while(size--)
		*out++=(char)toupper(*in++);
}

struct Connection {
	SQL_Driver_services* services;

	MYSQL* handle;
	const char* cstrClientCharset;
	bool autocommit;
};

/**
	MySQL server driver
*/
class MySQL_Driver : public SQL_Driver {
public:

	MySQL_Driver() : SQL_Driver() {
	}

	/// get api version
	int api_version() { return SQL_DRIVER_API_VERSION; }
	/// initialize driver by loading sql dynamic link library
	const char *initialize(char *dlopen_file_spec) {
		return dlopen_file_spec?
			dlink(dlopen_file_spec):"client library column is empty";
	}
	/**	connect
		@param url
			format: @b user:pass@host[:port]|[/unix/socket]/database?
				charset=cp1251_koi8&
				timeout=3&
				compress=1&
				named_pipe=1
			3.23.22b
			Currently the only option for @b character_set_name is cp1251_koi8.
			WARNING: must be used only to connect, for buffer doesn't live long
	*/
	void connect(
		char *url, 
		SQL_Driver_services& services, 
		void **connection_ref ///< output: Connection*
		) {
		char *user=url;
		char *s=rsplit(user, '@');
		char *host=0;
		char *unix_socket=0;
		if(s && s[0]=='[') { // unix socket
			unix_socket=1+s;
			s=lsplit(unix_socket, ']');
		} else { // IP
			host=s;
		}
		char *db=lsplit(s, '/');
		char *pwd=lsplit(user, ':');
		char *error_pos=0;
		char *port_cstr=lsplit(host, ':');
		int port=port_cstr?strtol(port_cstr, &error_pos, 0):0;
		char *options=lsplit(db, '?');

		char *cstrBackwardCompAskServerToTranscode=0;

		Connection& connection=*(Connection  *)services.malloc(sizeof(Connection));
		connection.services=&services;
	    connection.handle=mysql_init(NULL);
		connection.cstrClientCharset=0;	
		connection.autocommit=true;
		*connection_ref=&connection;

		while(options) {
			if(char *key=lsplit(&options, '&')) {
				if(*key) {
					if(char *value=lsplit(key, '=')) {
						if(strcmp(key, "ClientCharset" ) == 0) {
							toupper_str(value, value, strlen(value));
							connection.cstrClientCharset=value;
						} else if(strcasecmp(key, "charset")==0) { // left for backward compatibility, consider using ClientCharset
							cstrBackwardCompAskServerToTranscode=value;
						} else if(strcasecmp(key, "timeout")==0) {
							unsigned int timeout=(unsigned int)atoi(value);
							if(mysql_options(connection.handle, MYSQL_OPT_CONNECT_TIMEOUT, (const char *)&timeout)!=0)
								services._throw(mysql_error(connection.handle));
						} else if(strcasecmp(key, "compress")==0) {
							if(atoi(value))
								if(mysql_options(connection.handle, MYSQL_OPT_COMPRESS, 0)!=0)
									services._throw(mysql_error(connection.handle));
						} else if(strcasecmp(key, "named_pipe")==0) {
							if(atoi(value))
								if(mysql_options(connection.handle, MYSQL_OPT_NAMED_PIPE , 0)!=0)
									services._throw(mysql_error(connection.handle));
						} else if(strcasecmp(key, "autocommit")==0) {
							if(atoi(value)==0) {
								connection.autocommit=false;
							}
						} else
							services._throw("unknown connect option" /*key*/);
					} else 
						services._throw("connect option without =value" /*key*/);
				}
			}
		}

		if(connection.cstrClientCharset && cstrBackwardCompAskServerToTranscode)
			services._throw("use 'ClientCharset' option only, "
				"'charset' option is obsolete and should not be used with new 'ClientCharset' option");

		if(!mysql_real_connect(connection.handle, 
			host, user, pwd, db, port?port:MYSQL_PORT, unix_socket, 0))
			services._throw(mysql_error(connection.handle));

		if(cstrBackwardCompAskServerToTranscode) {
			// set charset
			char statement[MAX_STRING]="set CHARACTER SET "; // cp1251_koi8
			strncat(statement, cstrBackwardCompAskServerToTranscode, MAX_STRING);
			
			exec(connection, statement);
		}

		if(!connection.autocommit)
			exec(connection, "set autocommit=0");
	}

	void exec(Connection& connection, const char* statement) {
		if(mysql_query(connection.handle, statement)) 
			connection.services->_throw(mysql_error(connection.handle));
		(*mysql_store_result)(connection.handle); // throw out the result [don't need but must call]
	}

	void disconnect(void *aconnection) {
		Connection& connection=*static_cast<Connection*>(aconnection);

		mysql_close(connection.handle);
		connection.handle=0;
	}
	void commit(void *aconnection) {
		//_asm int 3;
		Connection& connection=*static_cast<Connection*>(aconnection);

		if(!connection.autocommit)
			exec(connection, "commit");
	}
	void rollback(void *aconnection) {
		Connection& connection=*static_cast<Connection*>(aconnection);

		if(!connection.autocommit)
			exec(connection, "rollback");
	}

	bool ping(void *aconnection) {
		Connection& connection=*static_cast<Connection*>(aconnection);

		return mysql_ping(connection.handle)==0;
	}

	const char* quote(void *aconnection, const char *from, unsigned int length) {
		Connection& connection=*static_cast<Connection*>(aconnection);
		/*
			3.23.22b
			You must allocate the to buffer to be at least length*2+1 bytes long. 
			(In the worse case, each character may need to be encoded as using two bytes, 
			and you need room for the terminating null byte.)
		*/
		char *result=(char*)connection.services->malloc_atomic(length*2+1);
		mysql_escape_string(result, from, length);
		return result;
	}
	void query(void *aconnection, 
		const char *astatement, 
		size_t placeholders_count, Placeholder* placeholders, 
		unsigned long offset, unsigned long limit,
		SQL_Driver_query_event_handlers& handlers) {
		Connection& connection=*static_cast<Connection*>(aconnection);
		SQL_Driver_services& services=*connection.services;
		const char* cstrClientCharset=connection.cstrClientCharset;
		MYSQL_RES *res=NULL;

		if(placeholders_count>0)
			services._throw("bind variables not supported (yet)");

		// transcode from $request:charset to connect-string?client_charset
		if(cstrClientCharset) {
			size_t transcoded_statement_size;
			services.transcode(astatement, strlen(astatement),
				astatement, transcoded_statement_size,
				services.request_charset(),
				cstrClientCharset);
		}

		const char *statement;
		if(offset || limit) {
			size_t statement_size=strlen(astatement);
			char *statement_limited=(char *)services.malloc_atomic(
				statement_size+MAX_NUMBER*2+8/* limit #,#*/+1);
			char *cur=statement_limited;
			memcpy(cur, astatement, statement_size); cur+=statement_size;
			cur+=sprintf(cur, " limit ");
			if(offset)
				cur+=snprintf(cur, MAX_NUMBER+1, "%u,", offset);
			if(limit)
				cur+=snprintf(cur, MAX_NUMBER, "%u", limit);
			statement=statement_limited;
		} else
			statement=astatement;

		if(mysql_query(connection.handle, statement)) 
			services._throw(mysql_error(connection.handle));
		if(!(res=mysql_store_result(connection.handle)) && mysql_field_count(connection.handle)) 
			services._throw(mysql_error(connection.handle));
		if(!res) // empty result: insert|delete|update|...
			return;
		
		int column_count=mysql_num_fields(res);
		if(!column_count) // old client
			column_count=mysql_field_count(connection.handle);

		if(!column_count) {
			mysql_free_result(res);
			services._throw("result contains no columns");
		}
		
		bool failed=false;
		SQL_Error sql_error;
#define CHECK(afailed) \
		if(afailed) { \
			failed=true; \
			goto cleanup; \
		}

		for(int i=0; i<column_count; i++){
			if(MYSQL_FIELD *field=mysql_fetch_field(res)) {
				size_t length=strlen(field->name);
				char* strm=(char*)services.malloc_atomic(length+1);
				memcpy(strm, field->name, length+1);
				const char* str=strm;

				// transcode to $request:charset from connect-string?client_charset
				if(cstrClientCharset) {
					services.transcode(str, length,
						str, length,
						cstrClientCharset,
						services.request_charset());
				}
				
				CHECK(handlers.add_column(sql_error, str, length));
			} else {
			    // seen some broken client, 
			    // which reported "44" for column count of response to "select 2+2"
			    column_count=i;
			    break;
			}
		}

		CHECK(handlers.before_rows(sql_error));
		
  		while(MYSQL_ROW mysql_row=mysql_fetch_row(res)) {
  			CHECK(handlers.add_row(sql_error));
  			unsigned long *lengths=mysql_fetch_lengths(res);
  			for(int i=0; i<column_count; i++){
  				size_t length=(size_t)lengths[i];
				const char* str;
  				if(length) {
  					char *strm=(char*)services.malloc_atomic(length+1);
  					memcpy(strm, mysql_row[i], length);
					strm[length]=0;
					str=strm;

					// transcode to $request:charset from connect-string?client_charset
					if(cstrClientCharset)
						services.transcode(str, length,
							str, length,
							cstrClientCharset,
							services.request_charset());
  				} else
  					str=0;
  				CHECK(handlers.add_row_cell(sql_error, str, length));
  			}
  		}
cleanup:
		mysql_free_result(res);
		if(failed)
			services._throw(sql_error);
	}

private: // mysql client library funcs

	typedef MYSQL* (STDCALL *t_mysql_init)(MYSQL *); 	t_mysql_init mysql_init;
	
	typedef int (STDCALL *t_mysql_options)(MYSQL *mysql, enum mysql_option option, const char *arg); t_mysql_options mysql_options;
	
	typedef MYSQL_RES* (STDCALL *t_mysql_store_result)(MYSQL *); t_mysql_store_result mysql_store_result;
	
	typedef int		(STDCALL *t_mysql_query)(MYSQL *, const char *q); t_mysql_query mysql_query;
	
	typedef char * (STDCALL *t_mysql_error)(MYSQL *); t_mysql_error mysql_error;
	static char* STDCALL subst_mysql_error(MYSQL *mysql) { return (mysql)->net.last_error; }

	typedef MYSQL*		(STDCALL *t_mysql_real_connect)(MYSQL *, const char *host,
					   const char *user,
					   const char *passwd,
					   const char *db,
					   unsigned int port,
					   const char *unix_socket,
					   unsigned int clientflag); t_mysql_real_connect mysql_real_connect;

	typedef void		(STDCALL *t_mysql_close)(MYSQL *); t_mysql_close mysql_close;
	
	typedef int		(STDCALL *t_mysql_ping)(MYSQL *); t_mysql_ping mysql_ping;
	
	typedef unsigned long	(STDCALL *t_mysql_escape_string)(char *to,const char *from,
					    unsigned long from_length); t_mysql_escape_string mysql_escape_string;
	
	typedef void		(STDCALL *t_mysql_free_result)(MYSQL_RES *result); t_mysql_free_result mysql_free_result;
	
	typedef unsigned long* (STDCALL *t_mysql_fetch_lengths)(MYSQL_RES *result); t_mysql_fetch_lengths mysql_fetch_lengths;
	
	typedef MYSQL_ROW	(STDCALL *t_mysql_fetch_row)(MYSQL_RES *result); t_mysql_fetch_row mysql_fetch_row;
	
	typedef MYSQL_FIELD*	(STDCALL *t_mysql_fetch_field)(MYSQL_RES *result); t_mysql_fetch_field mysql_fetch_field;
	
	typedef unsigned int (STDCALL *t_mysql_num_fields)(MYSQL_RES *); t_mysql_num_fields mysql_num_fields;
	static unsigned int STDCALL subst_mysql_num_fields(MYSQL_RES *res) { return res->field_count; }

	typedef unsigned int (STDCALL *t_mysql_field_count)(MYSQL *); t_mysql_field_count mysql_field_count;
	static unsigned int STDCALL subst_mysql_field_count(MYSQL *mysql) { return mysql->field_count; }

private: // mysql client library funcs linking

	const char *dlink(const char *dlopen_file_spec) {
		if(lt_dlinit())
			return lt_dlerror();
        lt_dlhandle handle=lt_dlopen(dlopen_file_spec);
        if (!handle) {
            if(const char* result=lt_dlerror())
            	return result;

			return "can not open the dynamic link module";
		}

		#define DSLINK(name, action) \
			name=(t_##name)lt_dlsym(handle, #name); \
				if(!name) \
					action;

		#define DLINK(name) DSLINK(name, return "function " #name " was not found")
		#define SLINK(name) DSLINK(name, name=subst_##name)
		
		DLINK(mysql_init);
		DLINK(mysql_options);
		DLINK(mysql_store_result);
		DLINK(mysql_query);
		SLINK(mysql_error);
		DLINK(mysql_real_connect);
		DLINK(mysql_close);
		DLINK(mysql_ping);
		DLINK(mysql_escape_string);
		DLINK(mysql_free_result);
		DLINK(mysql_fetch_lengths);
		DLINK(mysql_fetch_row);
		DLINK(mysql_fetch_field);
		SLINK(mysql_num_fields);
		SLINK(mysql_field_count);
		return 0;
	}

};

extern "C" SQL_Driver *SQL_DRIVER_CREATE() {
	return new MySQL_Driver();
}