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 // Copyright 2022, David Lawrence
 // Subject to the terms in the LICENSE file found in the top-level directory.
 //
 //
 // This is a JANA event source that uses PODIO to read from a ROOT
 // file created using the EDM4hep Data Model.
 
 #include "JEventSourcePODIO.h"
 
 #include <JANA/JApplication.h>
 #include <JANA/JEvent.h>
 #include <JANA/JException.h>
 #include <JANA/Utils/JTypeInfo.h>
 #include <TFile.h>
 #include <TObject.h>
 #include <edm4hep/EventHeaderCollection.h>
 #include <fmt/format.h>
 #include <fmt/ostream.h>
 #include <podio/CollectionBase.h>
 #include <podio/Frame.h>
 #include <podio/podioVersion.h>
 #include <algorithm>
 #include <exception>
 #include <iostream>
 #include <map>
 #include <memory>
 #include <sstream>
 #include <string_view>
 #include <utility>
 #include <vector>
 
 #include "services/io/podio/datamodel_glue_compat.h"     // IWYU pragma: keep
 #include "services/io/podio/datamodel_includes_compat.h" // IWYU pragma: keep
 #include "services/log/Log_service.h"
 
 // Formatter for podio::version::Version
 template <> struct fmt::formatter<podio::version::Version> : ostream_formatter {};
 
 //------------------------------------------------------------------------------
 // InsertingVisitor
 //
 /// This datamodel visitor will insert a PODIO collection into a JEvent.
 /// This allows us to access the PODIO data through JEvent::Get and JEvent::GetCollection.
 /// This makes it transparent to downstream factories whether the data was loaded from file, or calculated.
 /// InsertingVisitor is called in GetEvent()
 ///
 /// \param event             JANA JEvent to copy the data objects into
 /// \param collection_name   name of the collection which will be used as the factory tag for these objects
 //------------------------------------------------------------------------------
 struct InsertingVisitor {
   // NOLINTBEGIN(cppcoreguidelines-avoid-const-or-ref-data-members): Lifetime of referenced objects is guaranteed beyond visitor lifetime in this pattern
   JEvent& m_event;
   const std::string& m_collection_name;
   // NOLINTEND(cppcoreguidelines-avoid-const-or-ref-data-members)
 
   InsertingVisitor(JEvent& event, const std::string& collection_name)
       : m_event(event), m_collection_name(collection_name) {};
 
   template <typename T> void operator()(const T& collection) {
 
     using ContentsT = decltype(collection[0]);
     m_event.InsertCollectionAlreadyInFrame<ContentsT>(&collection, m_collection_name);
   }
 };
 
 //------------------------------------------------------------------------------
 // Constructor
 //
 ///
 /// \param resource_name  Name of root file to open (n.b. file is not opened until Open() is called)
 /// \param app            JApplication
 //------------------------------------------------------------------------------
 JEventSourcePODIO::JEventSourcePODIO(std::string resource_name, JApplication* app)
     : JEventSource(resource_name, app) {
   SetTypeName(NAME_OF_THIS);                   // Provide JANA with class name
   SetCallbackStyle(CallbackStyle::ExpertMode); // Use new, exception-free Emit() callback
 
   // Get Logger
   m_log = GetApplication()->GetService<Log_service>()->logger("JEventSourcePODIO");
 
   // Tell JANA that we want it to call the FinishEvent() method.
   // EnableFinishEvent();
 
   // Allow user to specify to recycle events forever
   GetApplication()->SetDefaultParameter("podio:run_forever", m_run_forever,
                                         "set to true to recycle through events continuously");
 
   bool print_type_table = false;
   GetApplication()->SetDefaultParameter("podio:print_type_table", print_type_table,
                                         "Print list of collection names and their types");
 
   // Hopefully we won't need to reimplement background event merging. Using podio frames, it looks like we would
   // have to do a deep copy of all data in order to insert it into the same frame, which would probably be
   // quite inefficient.
   /*
     std::string background_filename;
     GetApplication()->SetDefaultParameter(
             "podio:background_filename",
             background_filename,
             "Name of file containing background events to merge in (default is not to merge any background)"
             );
 
     int num_background_events=1;
     GetApplication()->SetDefaultParameter(
             "podio:num_background_events",
             num_background_events,
             "Number of background events to add to every primary event."
     );
     */
 }
 
 //------------------------------------------------------------------------------
 // Destructor
 //------------------------------------------------------------------------------
 JEventSourcePODIO::~JEventSourcePODIO() {
   m_log->info("Closing Event Source for {}", GetResourceName());
 }
 
 //------------------------------------------------------------------------------
 // Open
 //
 /// Open the root file and read in metadata.
 //------------------------------------------------------------------------------
 void JEventSourcePODIO::Open() {
 
   bool print_type_table = GetApplication()->GetParameterValue<bool>("podio:print_type_table");
   // std::string background_filename = GetApplication()->GetParameterValue<std::string>("podio:background_filename");;
   // int num_background_events = GetApplication()->GetParameterValue<int>("podio:num_background_events");;
 
   // Open primary events file (auto-detects format: TTree or RNTuple)
   try {
 
     m_reader = std::make_unique<podio::Reader>(podio::makeReader(GetResourceName()));
 
     auto version          = m_reader->currentFileVersion();
     bool version_mismatch = version.major > podio::version::build_version.major;
     version_mismatch |= (version.major == podio::version::build_version.major) &&
                         (version.minor > podio::version::build_version.minor);
     if (version_mismatch) {
       std::stringstream ss;
       ss << "Mismatch in PODIO versions! " << version << " > " << podio::version::build_version;
       // FIXME: The podio ROOTReader is somehow failing to read in the correct version numbers from the file
       //            throw JException(ss.str());
     }
 
     m_log->info("PODIO version: file={} (executable={})", version, podio::version::build_version);
 
     Nevents_in_file = m_reader->getEntries("events");
     m_log->info("Opened PODIO file \"{}\" with {} events (format auto-detected)", GetResourceName(),
                 Nevents_in_file);
 
     if (print_type_table) {
       PrintCollectionTypeTable();
     }
   } catch (std::exception& e) {
     m_log->error(e.what());
     throw JException(fmt::format("Problem opening file \"{}\"", GetResourceName()));
   }
 }
 
 //------------------------------------------------------------------------------
 // Close
 //
 /// Cleanly close the resource when JANA is terminated via Ctrl-C or jana:nevents
 ///
 /// \param event
 //------------------------------------------------------------------------------
 void JEventSourcePODIO::Close() {
   // m_reader.close();
   // TODO: ROOTReader does not appear to have a close() method.
 }
 
 std::vector<std::string_view> JEventSourcePODIO::getAvailableCategories() const {
   return m_reader->getAvailableCategories();
 }
 
 std::size_t JEventSourcePODIO::getEntries(const std::string& category) const {
   return m_reader->getEntries(category);
 }
 
 podio::Frame JEventSourcePODIO::getFrame(const std::string& category, std::size_t index) const {
   return m_reader->readFrame(category, index);
 }
 
 //------------------------------------------------------------------------------
 // GetEvent
 //
 /// Read next event from file and copy its objects into the given JEvent.
 ///
 /// \param event
 //------------------------------------------------------------------------------
 JEventSourcePODIO::Result JEventSourcePODIO::Emit(JEvent& event) {
 
   /// Calls to GetEvent are synchronized with each other, which means they can
   /// read and write state on the JEventSource without causing race conditions.
 
   // Check if we have exhausted events from file
   if (Nevents_read >= Nevents_in_file) {
     if (m_run_forever) {
       Nevents_read = 0;
     } else {
       return Result::FailureFinished;
     }
   }
 
   auto frame = std::make_unique<podio::Frame>(m_reader->readFrame("events", Nevents_read));
 
   if (m_use_event_headers) {
     const auto& event_headers = frame->get<edm4hep::EventHeaderCollection>("EventHeader");
     if (event_headers.size() != 1) {
       m_log->warn("Missing or bad event headers: Entry {} contains {} items, but 1 expected. Will "
                   "not use event and run numbers from header",
                   Nevents_read, event_headers.size());
       m_use_event_headers = false;
     } else {
       event.SetEventNumber(event_headers[0].getEventNumber());
       event.SetRunNumber(event_headers[0].getRunNumber());
     }
   }
 
   // Insert contents odf frame into JFactories
   VisitPodioCollection<InsertingVisitor> visit;
   for (const std::string& coll_name : frame->getAvailableCollections()) {
     const podio::CollectionBase* collection = frame->get(coll_name);
     InsertingVisitor visitor(event, coll_name);
     visit(visitor, *collection);
   }
 
   event.Insert(frame.release()); // Transfer ownership from unique_ptr to JFactoryT<podio::Frame>
   Nevents_read += 1;
   return Result::Success;
 }
 
 //------------------------------------------------------------------------------
 // GetDescription
 //------------------------------------------------------------------------------
 std::string JEventSourcePODIO::GetDescription() {
 
   /// GetDescription() helps JANA explain to the user what is going on
   return "PODIO root file (Frames, podio >= v0.16.3)";
 }
 
 //------------------------------------------------------------------------------
 // CheckOpenable
 //
 /// Return a value from 0-1 indicating probability that this source will be
 /// able to read this root file. Currently, it simply checks that the file
 /// name contains the string ".root" and if does, returns a small number (0.02).
 /// This will need to be made more sophisticated if the alternative root file
 /// formats need to be supported by other event sources.
 ///
 /// \param resource_name name of root file to evaluate.
 /// \return              value from 0-1 indicating confidence that this source can open the given file
 //------------------------------------------------------------------------------
 template <>
 double JEventSourceGeneratorT<JEventSourcePODIO>::CheckOpenable(std::string resource_name) {
 
   // PODIO Frame reader gets slightly higher precedence than PODIO Legacy reader, but only if the file
   // contains a 'podio_metadata' TTree. If the file doesn't exist, this will return 0. The "file not found"
   // error will hopefully be generated by the PODIO legacy reader instead.
   if (resource_name.find(".root") == std::string::npos) {
     return 0.0;
   }
 
   // PODIO FrameReader segfaults on legacy input files, so we use ROOT to validate beforehand. Of course,
   // we can't validate if ROOT can't read the file.
   std::unique_ptr<TFile> file = std::unique_ptr<TFile>{TFile::Open(resource_name.c_str())};
   if (!file || file->IsZombie()) {
     return 0.0;
   }
 
   // We test the format the same way that PODIO's python API does. See python/podio/reading.py
   TObject* tree = file->Get("podio_metadata");
   if (tree == nullptr) {
     return 0.0;
   }
   return 0.03;
 }
 
 //------------------------------------------------------------------------------
 // PrintCollectionTypeTable
 //
 /// Print the list of collection names from the currently open file along
 /// with their types. This will be called automatically when the file is
 /// open if the PODIO:PRINT_TYPE_TABLE variable is set to a non-zero value
 //------------------------------------------------------------------------------
 void JEventSourcePODIO::PrintCollectionTypeTable() {
 
   // Read the zeroth entry. This assumes that m_reader has already been initialized with a valid filename
   auto frame = std::make_unique<podio::Frame>(m_reader->readFrame("events", 0));
 
   std::map<std::string, std::string> collectionNames;
   std::size_t max_name_len = 0;
   std::size_t max_type_len = 0;
 
   // Record all (collection name, value type name) pairs
   // Record the maximum length of both strings so that we can print nicely aligned columns.
   for (const std::string& name : frame->getAvailableCollections()) {
     const podio::CollectionBase* coll = frame->get(name);
     const auto type                   = coll->getTypeName();
     max_name_len                      = std::max(max_name_len, name.length());
     max_type_len                      = std::max(max_type_len, type.length());
     collectionNames[name]             = std::string(type);
   }
 
   // Print table
   std::cout << std::endl;
   std::cout << "Available Collections" << std::endl;
   std::cout << std::endl;
   std::cout << "Collection Name"
             << std::string(max_name_len + 2 - std::string("Collection Name").length(), ' ')
             << "Data Type" << std::endl;
   std::cout << std::string(max_name_len, '-') << "  " << std::string(max_name_len, '-')
             << std::endl;
   for (auto& [name, type] : collectionNames) {
     std::cout << name + std::string(max_name_len + 2 - name.length(), ' ');
     std::cout << type << std::endl;
   }
   std::cout << std::endl;
 }

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