    // @(#)root/base:$Name:  $:$Id: TPluginManager.cxx,v 1.26 2005/06/22 20:18:10 brun Exp $
    // Author: Fons Rademakers   26/1/2002

    /*************************************************************************
     * Copyright (C) 1995-2002, Rene Brun and Fons Rademakers.               *
     * All rights reserved.                                                  *
     *                                                                       *
     * For the licensing terms see $ROOTSYS/LICENSE.                         *
     * For the list of contributors see $ROOTSYS/README/CREDITS.             *
     *************************************************************************/

    //////////////////////////////////////////////////////////////////////////
    //                                                                      //
    // TPluginManager                                                       //
    //                                                                      //
    // This class implements a plugin library manager. It keeps track of    //
    // a list of plugin handlers. A plugin handler knows which plugin       //
    // library to load to get a specific class that is used to extend the   //
    // functionality of a specific base class and how to create an object   //
    // of this class. For example, to extend the base class TFile to be     //
    // able to read RFIO files one needs to load the plugin library         //
    // libRFIO.so which defines the TRFIOFile class. This loading should    //
    // be triggered when a given URI contains a regular expression defined  //
    // by the handler. Handlers can be defined for example as resources     //
    // in the .rootrc file, e.g.:                                           //
    //                                                                      //
    //   Plugin.TFile:       ^rfio:   TRFIOFile    RFIO   "<constructor>"   //
    //   Plugin.TSQLServer:  ^mysql:  TMySQLServer MySQL  "<constructor>"   //
    //   +Plugin.TSQLServer: ^pgsql:  TPgSQLServer PgSQL  "<constructor>"   //
    //   Plugin.TVirtualFitter: *     TFitter      Minuit "TFitter(Int_t)"  //
    //                                                                      //
    // Where the + in front of Plugin.TSQLServer says that it extends the   //
    // existing definition of TSQLServer, usefull when there is more than   //
    // one plugin that can extend the same base class. The "<constructor>"  //
    // should be the constructor or a static method that generates an       //
    // instance of the specified class. Global methods should start with    //
    // "::" in their name, like "::CreateFitter()".                         //
    // Instead of being a shared library a plugin can also be a CINT        //
    // script, so instead of libDialog.so one can have Dialog.C.            //
    // The * is a placeholder in case there is no need for a URI to         //
    // differentiate between different plugins for the same base class.     //
    // For the default plugins see $ROOTSYS/etc/system.rootrc.              //
    //                                                                      //
    // Plugin handlers can also be registered at run time, e.g.:            //
    //                                                                      //
    //   gROOT->GetPluginManager()->AddHandler("TSQLServer", "^sapdb:",     //
    //                                         "TSapDBServer", "SapDB",     //
    //             "TSapDBServer(const char*,const char*, const char*)");   //
    //                                                                      //
    // A list of currently defined handlers can be printed using:           //
    //                                                                      //
    //   gROOT->GetPluginManager()->Print(); // use option="a" to see ctors //
    //                                                                      //
    // The use of the plugin library manager removes all textual references //
    // to hard-coded class and library names and the resulting dependencies //
    // in the base classes. The plugin manager is used to extend a.o.       //
    // TFile, TSQLServer, TGrid, etc. functionality.                        //
    //                                                                      //
    //////////////////////////////////////////////////////////////////////////

    #include "TPluginManager.h"
    #include "TEnv.h"
    #include "TRegexp.h"
    #include "TROOT.h"
    #include "TList.h"
    #include "TOrdCollection.h"
    #include "Varargs.h"
    #include "TClass.h"
    #include "TCint.h"
    #include "TMethod.h"
    #include "TMethodArg.h"
    #include "TDataType.h"
    #include "TMethodCall.h"
    #include "TVirtualMutex.h"

    ClassImp(TPluginHandler)

    //______________________________________________________________________________
    TPluginHandler::TPluginHandler(const char *base, const char *regexp,
                                   const char *className, const char *pluginName,
                                   const char *ctor)
    {
       // Create a plugin handler. Called by TPluginManager.

       fBase     = base;
       fRegexp   = regexp;
       fClass    = className;
       fPlugin   = pluginName;
       fCtor     = ctor;
       fCallEnv  = 0;
       fCanCall  = 0;
       fIsMacro  = kFALSE;
       fIsGlobal = kFALSE;

       if (gROOT->LoadMacro(pluginName, 0, kTRUE) == 0)
          fIsMacro = kTRUE;

       if (fCtor.Contains("::")) {
          fIsGlobal = kTRUE;
          fCtor = fCtor.Strip(TString::kLeading, ':');
       }
    }

    //______________________________________________________________________________
    TPluginHandler::~TPluginHandler()
    {
       // Cleanup plugin handler object.

       delete fCallEnv;
    }

    //______________________________________________________________________________
    Bool_t TPluginHandler::CanHandle(const char *base, const char *uri)
    {
       // Check if regular expression appears in the URI, if so return kTRUE.
       // If URI = 0 always return kTRUE.

       if (fBase != base)
          return kFALSE;

       if (!uri || fRegexp == "*")
          return kTRUE;

       Bool_t wildcard = kFALSE;
       if (!fRegexp.MaybeRegexp())
          wildcard = kTRUE;

       TRegexp re(fRegexp, wildcard);
       TString ruri = uri;

       if (ruri.Index(re) != kNPOS)
          return kTRUE;
       return kFALSE;
    }

    //______________________________________________________________________________
    void TPluginHandler::SetupCallEnv()
    {
       // Setup ctor or static method call environment.

       fCanCall = -1;

       // check if class exists
       TClass *cl = gROOT->GetClass(fClass);
       if (!cl && !fIsGlobal) {
          Error("SetupCallEnv", "class %s not found in plugin %s", fClass.Data(),
                fPlugin.Data());
          return;
       }

       // split method and prototype strings
       TString method = fCtor(0, fCtor.Index("("));
       TString proto  = fCtor(fCtor.Index("(")+1, fCtor.Index(")")-fCtor.Index("(")-1);

       if (fIsGlobal) {
          cl = 0;
          if (fIsMacro)
             fMethod = gROOT->GetGlobalFunction(method, 0, kTRUE);  // to be fixed
          else
             fMethod = gROOT->GetGlobalFunctionWithPrototype(method, proto, kTRUE);
       } else {
          if (fIsMacro)
             fMethod = cl->GetMethodAny(method);  //to be fixed to use prototype
          else
             fMethod = cl->GetMethodWithPrototype(method, proto);
       }

       if (!fMethod) {
          if (fIsGlobal)
             Error("SetupCallEnv", "global function %s not found", method.Data());
          else
             Error("SetupCallEnv", "method %s not found in class %s", method.Data(),
                   fClass.Data());
          return;
       }

       if (!fIsGlobal && !(fMethod->Property() & kIsPublic)) {
          Error("SetupCallEnv", "method %s is not public", method.Data());
          return;
       }

       fCallEnv = new TMethodCall;
       fCallEnv->InitWithPrototype(cl, method, proto);

       fCanCall = 1;

       return;
    }

    //______________________________________________________________________________
    Int_t TPluginHandler::CheckPlugin()
    {
       // Check if the plugin library for this handler exits. Returns 0
       // when it exists and -1 in case the plugin does not exist.

       if (fIsMacro) {
          if (gROOT->GetClass(fClass)) return 0;
          return gROOT->LoadMacro(fPlugin, 0, kTRUE);
       } else
          return gROOT->LoadClass(fClass, fPlugin, kTRUE);
    }

    //______________________________________________________________________________
    Int_t TPluginHandler::LoadPlugin()
    {
       // Load the plugin library for this handler. Returns 0 on successful loading
       // and -1 in case the library does not exist or in case of error.

       if (fIsMacro) {
          if (gROOT->GetClass(fClass)) return 0;
          return gROOT->LoadMacro(fPlugin);
       } else
          return gROOT->LoadClass(fClass, fPlugin);
    }

    //______________________________________________________________________________
    Long_t TPluginHandler::ExecPlugin(Int_t va_(nargs), ...)
    {
       // Execute ctor for this plugin and return pointer to object of specific
       // class. User must cast the returned long to the correct class.
       // This method accepts a variable number of arguments to be passed
       // to the ctor, where nargs is the number of arguments, followed
       // by nargs arguments. Returns 0 in case of error.

       if (fCtor.IsNull()) {
          Error("ExecPlugin", "no ctor specified for this handler %s", fClass.Data());
          return 0;
       }

       if (!fCallEnv && !fCanCall)
          SetupCallEnv();

       if (fCanCall == -1)
          return 0;

       if (nargs < fMethod->GetNargs() - fMethod->GetNargsOpt() ||
           nargs > fMethod->GetNargs()) {
          Error("ExecPlugin", "nargs (%d) not consistent with expected number of arguments ([%d-%d])",
                nargs, fMethod->GetNargs() - fMethod->GetNargsOpt(),
                fMethod->GetNargs());
          return 0;
       }

       R__LOCKGUARD2(gCINTMutex);

       fCallEnv->ResetParam();

       if (nargs > 0) {
          TIter next(fMethod->GetListOfMethodArgs());
          TMethodArg *arg;

          va_list ap;
          va_start(ap, va_(nargs));

          for (int i = 0; i < nargs; i++) {
             arg = (TMethodArg*) next();
             TString type = arg->GetFullTypeName();
             TDataType *dt = gROOT->GetType(type);
             if (dt)
                type = dt->GetFullTypeName();
             if (arg->Property() & (kIsPointer | kIsArray | kIsReference))
                fCallEnv->SetParam((Long_t) va_arg(ap, void*));
             else if (type == "bool")
                fCallEnv->SetParam((Long_t) va_arg(ap, int));  // bool is promoted to int
             else if (type == "char" || type == "unsigned char")
                fCallEnv->SetParam((Long_t) va_arg(ap, int));  // char is promoted to int
             else if (type == "short" || type == "unsigned short")
                fCallEnv->SetParam((Long_t) va_arg(ap, int));  // short is promoted to int
             else if (type == "int" || type == "unsigned int")
                fCallEnv->SetParam((Long_t) va_arg(ap, int));
             else if (type == "long" || type == "unsigned long")
                fCallEnv->SetParam((Long_t) va_arg(ap, long));
             else if (type == "long long")
                fCallEnv->SetParam((Long64_t) va_arg(ap, Long64_t));
             else if (type == "unsigned long long")
                fCallEnv->SetParam((ULong64_t) va_arg(ap, ULong64_t));
             else if (type == "float")
                fCallEnv->SetParam((Double_t) va_arg(ap, double));  // float is promoted to double
             else if (type == "double")
                fCallEnv->SetParam((Double_t) va_arg(ap, double));
          }

          va_end(ap);
       }

       Long_t ret;
       fCallEnv->Execute(ret);

       return ret;
    }

    ClassImp(TPluginManager)

    //______________________________________________________________________________
     TPluginManager::~TPluginManager()
    {
       // Clean up the plugin manager.

       delete fHandlers;
    }

    //______________________________________________________________________________
     void TPluginManager::LoadHandlersFromEnv(TEnv *env)
    {
       // Load plugin handlers specified in config file, like:
       //    Plugin.TFile:       ^rfio:    TRFIOFile      RFIO  "TRFIOFile(...)"
       //    Plugin.TSQLServer:  ^mysql:   TMySQLServer   MySQL "TMySQLServer(...)"
       //    +Plugin.TSQLServer: ^pgsql:   TPgSQLServer   PgSQL "TPgSQLServer(...)"
       // The + allows the extension of an already defined resource (see TEnv).

       if (!env) return;

       TIter next(env->GetTable());
       TEnvRec *er;

       while ((er = (TEnvRec*) next())) {
          const char *s;
          if ((s = strstr(er->GetName(), "Plugin."))) {
             // use s, i.e. skip possible OS and application prefix to Plugin.
             // so that GetValue() takes properly care of returning the value
             // for the specified OS and/or application
             const char *val = env->GetValue(s, (const char*)0);
             if (val) {
                Int_t cnt = 0;
                char *v = StrDup(val);
                s += 7;
                while (1) {
                   TString regexp = strtok(!cnt ? v : 0, "; ");
                   if (regexp.IsNull()) break;
                   TString clss   = strtok(0, "; ");
                   if (clss.IsNull()) break;
                   TString plugin = strtok(0, "; ");
                   if (plugin.IsNull()) break;
                   TString ctor = strtok(0, ";\"");
                   if (!ctor.Contains("("))
                      ctor = strtok(0, ";\"");
                   AddHandler(s, regexp, clss, plugin, ctor);
                   cnt++;
                }
                delete [] v;
             }
          }
       }
    }

    //______________________________________________________________________________
     void TPluginManager::AddHandler(const char *base, const char *regexp,
                                    const char *className, const char *pluginName,
                                    const char *ctor)
    {
       // Add plugin handler to the list of handlers. If there is already a
       // handler defined for the same base and regexp it will be replaced.

       if (!fHandlers) {
          fHandlers = new TList;
          fHandlers->IsOwner();
       }

       // make sure there is no previous handler for the same case
       RemoveHandler(base, regexp);

       TPluginHandler *h = new TPluginHandler(base, regexp, className,
                                              pluginName, ctor);
       fHandlers->Add(h);
    }

    //______________________________________________________________________________
     void TPluginManager::RemoveHandler(const char *base, const char *regexp)
    {
       // Remove handler for the specified base class and the specified
       // regexp. If regexp=0 remove all handlers for the specified base.

       if (!fHandlers) return;

       TIter next(fHandlers);
       TPluginHandler *h;

       while ((h = (TPluginHandler*) next())) {
          if (h->fBase == base) {
             if (!regexp || h->fRegexp == regexp) {
                fHandlers->Remove(h);
                delete h;
             }
          }
       }
    }

    //______________________________________________________________________________
     TPluginHandler *TPluginManager::FindHandler(const char *base, const char *uri)
    {
       // Returns the handler if there exists a handler for the specified URI.
       // The uri can be 0 in which case the first matching plugin handler
       // will be returned. Returns 0 in case handler is not found.

       if (!fHandlers) return 0;

       TIter next(fHandlers);
       TPluginHandler *h;

       while ((h = (TPluginHandler*) next())) {
          if (h->CanHandle(base, uri)) {
             if (gDebug > 0)
                Info("FindHandler", "found plugin for %s", h->GetClass());
             return h;
          }
       }

       if (gDebug > 0) {
          if (uri)
             Info("FindHandler", "did not find plugin for class %s and uri %s", base, uri);
          else
             Info("FindHandler", "did not find plugin for class %s", base);
       }

       return 0;
    }

    //______________________________________________________________________________
     void TPluginManager::Print(Option_t *opt) const
    {
       // Print list of registered plugin handlers. If option is "a" print
       // also the ctor's that will be used.

       if (!fHandlers) return;

       TIter next(fHandlers);
       TPluginHandler *h;

       printf("=====================================================================\n");
       printf("Base                 Regexp        Class              Plugin\n");
       printf("=====================================================================\n");

       while ((h = (TPluginHandler*) next())) {
          const char *exist = "";
          if (h->CheckPlugin() == -1)
             exist = " [*]";
          printf("%-20s %-13s %-18s %s%s\n", h->fBase.Data(), h->fRegexp.Data(),
                 h->fClass.Data(), h->fPlugin.Data(), exist);
          if (strchr(opt, 'a'))
             printf("  [Ctor: %s]\n", h->fCtor.Data());
       }
       printf("=====================================================================\n");
       printf("[*] plugin not available\n");
       printf("=====================================================================\n\n");
    }