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 //
 // Copyright 2020, Jefferson Science Associates, LLC.
 // Subject to the terms in the LICENSE file found in the top-level directory.
 
 
 #include <thread>
 #include <mutex>
 #include <chrono>
 using namespace std;
 
 
 #include <JANA/JApplication.h>
 #include <JANA/Utils/JCpuInfo.h>
 #include <JANA/Services/JParameterManager.h>
 
 #include <janapy.h>
 #include <pybind11/embed.h>
 
 extern std::mutex pymutex;    // declared in JEventProcessorPY.h
 
 void JANA_EmbeddedPythonModuleInit(JApplication *sApp);
 
 extern "C"{
 __attribute__((visibility("default")))  // counteract the -fvisibility=hidden compiler option
 void InitPlugin(JApplication *app){
     InitJANAPlugin(app);
 
     // Launch thread to set up python interface and execute user script.
     // This is done in a thread in case the script needs to continue
     // running throughout the life of the process.
     std::thread thr(JANA_EmbeddedPythonModuleInit, app);
     thr.detach();
 
     // Wait for python interface to set up and user script to execute
     // until it indicates it is ready for JANA system to continue.
     // This allows more control from python by stalling the initialization
     // so it has a chance to modify things a bit before full JANA
     // initialization completes and data processing starts.
     while( !PY_INITIALIZED ) std::this_thread::sleep_for (std::chrono::milliseconds(100));
 }
 
 void FinalizePlugin(JApplication */*app*/){
     // Finalize the python interpreter
     if( PY_INITIALIZED ) {
         // Wait upt to 2 seconds for interpreter to not be in use before finalizing it.
         for(int i=0; i<20; i++) {
             if (pymutex.try_lock()) {
                 PY_INITIALIZED = false;
                 // TODO: Fix this
                 //  There is an issue with seg faults when dlclose is called on the janapy plugin
                 //  if we call finalize here. I tried to ensure no other python methods were being
                 //  called, but couldn't find how to plug things up completely. Thus, to avoid
                 //  crashes when ending (especially when ctl-C is hit) we do not finalize the
                 //  python interpreter.
                 py::finalize_interpreter();
                 break;
             }
             std::this_thread::sleep_for(std::chrono::milliseconds(100));
         }
     }
 }
 } // "C"
 
 //.....................................................
 
 
 //================================================================================
 
 //-------------------------------------
 // JANA_EmbeddedPythonModuleInit
 //-------------------------------------
 void JANA_EmbeddedPythonModuleInit(JApplication *sApp)
 {
     /// This will initialize the jana Python system and import the
     /// JANA module (defined by the routines in this file). This gets called
     /// when the janapy plugin gets initialized. It will then automatically
     /// look for a file whose name is given by either the JANA_PYTHON_FILE
     /// config. parameter or environment variable in that order. If neither
     /// exists, it looks for a file name "jana.py" in the current working
     /// directory and if found, executes that. If you do not wish to execute
     /// a python file, then you can set the JANA_PYTHON_FILE value to an empty
     /// string (or better yet, just not attach the janapy plugin!).
     ///
     /// IMPORTANT: The janapy InitPlugin routine will block (resulting in the whole
     /// JANA system pausing) until either this routine finishes or the python script
     /// it invokes calls "jana.Start()" or "jana.Run()". This is to give the python script
     /// a chance to modify running conditions prior to event processing starting.
     /// If the python script intends to run throughout the life of the process,
     /// then it MUST call jana.Start() at some point. If the script is small and only
     /// runs for a short time, then you don't need to call it since it will be
     /// called automatically when the script ends.
 
     // Initialize the python interpreter. It will be finalized (shutdown)
     // when the plugin is detached in the FinalizePlugin routine above.
     py::initialize_interpreter();
 
     // Use existing JApplication.
     pyjapp = sApp;
 
     // Get name of python file to execute
     string fname = "jana.py";
     try{
         fname = pyjapp->GetParameterValue<string>("JANA_PYTHON_FILE");
     }catch(...){
         auto JANA_PYTHON_FILE = getenv("JANA_PYTHON_FILE");
         if( JANA_PYTHON_FILE ) fname = JANA_PYTHON_FILE;
     }
 
     // Fill in the script name in sys.argv. This is needed for tkinter which
     // is hardcoded to look at sys.argv[0].
     std::vector<wchar_t*> argv;
     auto wfname = std::wstring(fname.begin(), fname.end());
     argv.push_back( (wchar_t*)wfname.c_str() );
     PySys_SetArgv(argv.size(), argv.data());
 
     // Execute python script.
     // n.b. The script may choose to run for the lifetime of the program!
     try {
         std::cout << "[INFO] Executing python script: " << fname << std::endl;
         py::eval_file(fname);
         std::cout << "[INFO] Finished executing python script " << std::endl;
     }catch(std::runtime_error &e){
         std::cerr << std::endl;
         std::cerr << string(60, '-') << std::endl;
         std::cerr << "ERROR processing python file: \"" << fname << "\"" << std::endl;
         std::cerr << e.what() << std::endl;
         std::cerr << std::endl;
         if( string(e.what()).find("could not be opened!") != string::npos) {
             std::cerr << "Please make sure one of the following is true:" << std::endl;
             std::cerr << "  - The file \"" << fname << "\" exists" << std::endl;
             std::cerr << "  - The JANA_PYTHON_FILE config. parameter points to a file that exists" << std::endl;
             std::cerr << "  - The janapy plugin is not in the configuration for the job" << std::endl;
         }
         std::cerr << string(60, '-') << std::endl;
         std::cerr << std::endl;
         pyjapp->Quit();
     }
 
     PY_INITIALIZED = true;
 }
 
 
 //================================================================================
 // Module definition
 // The arguments of this structure tell Python what to call the extension,
 // what it's methods are and where to look for it's method definitions.
 // The routines themselves are all defined in src/python/common/janapy.h
 // and src/python/common/janapy.cc.
 PYBIND11_EMBEDDED_MODULE(jana, m) {
 
     m.doc() = "JANA2 Embedded Python Interface";
 
     // (see src/python/common/janapy.h)
     JANA_MODULE_DEF
 }

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