/*
 * Bridge for Perfetto C->C++
 * 
 * written by gback@vt.edu for CS3214 Spring 2024
 */

#include "perfetto.h"
#include "perfetto-bridge.h"
#include <fstream>

PERFETTO_DEFINE_CATEGORIES(
    perfetto::Category(LOCKING_CATEGORY).SetDescription("Lock Simulation"),
);
PERFETTO_TRACK_EVENT_STATIC_STORAGE();

// as per https://github.com/google/perfetto/blob/master/examples/sdk/example.cc
// and
// https://cs.android.com/android/platform/superproject/main/+/main:external/perfetto/src/tracing/test/api_integrationtest.cc;l=2241-2242;drc=d8fd1b45a91e019b1e98a3971155c7b0c579faf2
std::unique_ptr<perfetto::TracingSession> StartTracing() {
    // The trace config defines which types of data sources are enabled for
    // recording. In this example we just need the "track_event" data source,
    // which corresponds to the TRACE_EVENT trace points.
    perfetto::TraceConfig cfg;
    cfg.add_buffers()->set_size_kb(1024);
    auto* ds_cfg = cfg.add_data_sources()->mutable_config();
    ds_cfg->set_name("track_event");

    auto tracing_session = perfetto::Tracing::NewTrace();
    tracing_session->Setup(cfg);
    tracing_session->StartBlocking();
    return tracing_session;
}

void StopTracing(std::unique_ptr<perfetto::TracingSession> tracing_session, char *output_file_name) {
    // Make sure the last event is closed for this example.
    perfetto::TrackEvent::Flush();

    // Stop tracing and read the trace data.
    tracing_session->StopBlocking();
    std::vector<char> trace_data(tracing_session->ReadTraceBlocking());

    std::ofstream output;
    output.open(output_file_name, std::ios::out | std::ios::binary);
    output.write(&trace_data[0], std::streamsize(trace_data.size()));
    output.close();
    PERFETTO_LOG("Trace written to %s file.", output_file_name);
}

/*
 * Emit a start event labeled `event`
 */
void perfetto_trace_event_begin(const char *event, uint64_t timestamp)
{
    TRACE_EVENT_BEGIN(LOCKING_CATEGORY, event, timestamp);
}

/*
 * End the previously started event
 */
void perfetto_trace_event_end(uint64_t timestamp)
{
    TRACE_EVENT_END(LOCKING_CATEGORY, timestamp);
}

void perfetto_init(void)
{
    perfetto::TracingInitArgs args;
    args.backends |= perfetto::kInProcessBackend;
    perfetto::Tracing::Initialize(args);
    perfetto::TrackEvent::Register();
}

void perfetto_trace(void (*work)(void), char *tracefile)
{
    auto tracing_session = StartTracing();

    perfetto::ProcessTrack process_track = perfetto::ProcessTrack::Current();
    perfetto::protos::gen::TrackDescriptor desc = process_track.Serialize();
    desc.mutable_process()->set_process_name("Process");
    perfetto::TrackEvent::SetTrackDescriptor(process_track, desc);

    work();

    StopTracing(std::move(tracing_session), tracefile);
}