// Copyright 2026 Dolphin Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
// Offline ETL decoder. No process attach, memory read or thread suspension.
#define NOMINMAX
#include <windows.h>
#include <cstdio>
#include <cstring>
#include <cwchar>
#include <evntrace.h>
#include <map>
#include <memory>
#include <string>
#include <tdh.h>
#include <vector>

static constexpr GUID NATIVE = {
    0x54ee9231, 0x28be, 0x4ab0, {0x98, 0x1e, 0xb2, 0x6f, 0x97, 0x9c, 0x56, 0xa4}};
static FILE* output;
static unsigned long long decoded = 0, errors = 0, total = 0;
static std::map<std::string, std::vector<unsigned char>> schemas;
static bool inspect_system = false;
static unsigned inspected_schemas = 0, failed_schemas = 0;
static std::string UTF8(const wchar_t* value)
{
  if (!value || !*value)
    return {};
  int n = WideCharToMultiByte(CP_UTF8, 0, value, -1, nullptr, 0, nullptr, nullptr);
  std::string text(n, '\0');
  WideCharToMultiByte(CP_UTF8, 0, value, -1, text.data(), n, nullptr, nullptr);
  text.pop_back();
  return text;
}
static std::string Quote(const std::string& value)
{
  std::string result = "\"";
  for (unsigned char c : value)
  {
    if (c == '"' || c == '\\')
    {
      result += '\\';
      result += c;
    }
    else if (c < 32)
    {
      char escaped[7];
      std::snprintf(escaped, sizeof(escaped), "\\u%04x", c);
      result += escaped;
    }
    else
      result += c;
  }
  return result + '"';
}
static void WINAPI Event(PEVENT_RECORD record)
{
  ++total;
  const bool native = IsEqualGUID(record->EventHeader.ProviderId, NATIVE);
  std::string key(reinterpret_cast<const char*>(&record->EventHeader.ProviderId), sizeof(GUID));
  key.append(reinterpret_cast<const char*>(&record->EventHeader.EventDescriptor),
             sizeof(EVENT_DESCRIPTOR));
  auto& buffer = schemas[key];
  const bool first_schema = buffer.empty();
  if (native || buffer.empty())
  {
    ULONG bytes = 0;
    const ULONG status = TdhGetEventInformation(record, 0, nullptr, nullptr, &bytes);
    if (status != ERROR_INSUFFICIENT_BUFFER)
    {
      if (native)
        ++errors;
      else if (inspect_system && failed_schemas++ < 20)
        std::fprintf(stderr, "TDH missing: event=%u opcode=%u status=%lu\n",
                     record->EventHeader.EventDescriptor.Id,
                     record->EventHeader.EventDescriptor.Opcode, status);
      return;
    }
    buffer.resize(bytes);
    if (TdhGetEventInformation(record, 0, nullptr,
                               reinterpret_cast<PTRACE_EVENT_INFO>(buffer.data()),
                               &bytes) != ERROR_SUCCESS)
    {
      if (native)
        ++errors;
      buffer.clear();
      return;
    }
  }
  auto* info = reinterpret_cast<PTRACE_EVENT_INFO>(buffer.data());
  const auto text = [&](ULONG offset) -> std::string {
    return offset ? UTF8(reinterpret_cast<wchar_t*>(buffer.data() + offset)) : "";
  };
  std::string name = text(info->EventNameOffset);
  if (name.empty())
    name = text(info->TaskNameOffset) + "/" + text(info->OpcodeNameOffset);
  if (inspect_system && !native && first_schema && inspected_schemas++ < 300)
  {
    std::fprintf(stderr, "SCHEMA event=%u opcode=%u name=%s fields=",
                 record->EventHeader.EventDescriptor.Id,
                 record->EventHeader.EventDescriptor.Opcode, name.c_str());
    for (ULONG i = 0; i < info->TopLevelPropertyCount && i < 30; ++i)
      std::fprintf(stderr, "%s%s", i ? "," : "", text(info->EventPropertyInfoArray[i].NameOffset).c_str());
    std::fprintf(stderr, "\n");
  }
  bool interesting = native;
  // Keep scheduling and instruction pointer records for independent qualification.
  for (ULONG i = 0; i < info->TopLevelPropertyCount; ++i)
  {
    const auto field = text(info->EventPropertyInfoArray[i].NameOffset);
    if (field == "InstructionPointer" || field == "OldThreadId" || field == "TThreadId")
      interesting = true;
  }
  if (!interesting)
    return;
  std::string fields;
  for (ULONG i = 0; i < info->TopLevelPropertyCount; ++i)
  {
    const auto& property = info->EventPropertyInfoArray[i];
    if (property.Flags & PropertyStruct)
      continue;
    const auto field = text(property.NameOffset);
    PROPERTY_DATA_DESCRIPTOR descriptor{};
    descriptor.PropertyName = reinterpret_cast<ULONGLONG>(buffer.data() + property.NameOffset);
    descriptor.ArrayIndex = ULONG_MAX;
    ULONG size = 0;
    if (TdhGetPropertySize(record, 0, nullptr, 1, &descriptor, &size) != ERROR_SUCCESS ||
        size > 65536)
    {
      if (native)
        ++errors;
      continue;
    }
    std::vector<unsigned char> bytes(size + 2, 0);
    if (TdhGetProperty(record, 0, nullptr, 1, &descriptor, size, bytes.data()) != ERROR_SUCCESS)
    {
      if (native)
        ++errors;
      continue;
    }
    std::string value;
    const auto type = property.nonStructType.InType;
    if (type == TDH_INTYPE_UNICODESTRING)
      value = Quote(UTF8(reinterpret_cast<wchar_t*>(bytes.data())));
    else if (type == TDH_INTYPE_ANSISTRING)
      value = Quote(reinterpret_cast<char*>(bytes.data()));
    else if (size == 1 || size == 2 || size == 4 || size == 8)
    {
      unsigned long long number = 0;
      std::memcpy(&number, bytes.data(), size);
      value = std::to_string(number);
    }
    else
    {
      if (native)
        ++errors;
      continue;
    }
    if (!fields.empty())
      fields += ',';
    fields += Quote(field) + ':' + value;
  }
  std::fprintf(output,
               "{\"native\":%s,\"event\":%s,\"qpc\":%lld,\"pid\":%lu,\"tid\":%lu,\"cpu\":%u,"
               "\"opcode\":%u,\"data\":{%s}}\n",
               native ? "true" : "false", Quote(name).c_str(),
               record->EventHeader.TimeStamp.QuadPart, record->EventHeader.ProcessId,
               record->EventHeader.ThreadId, record->BufferContext.ProcessorNumber,
               record->EventHeader.EventDescriptor.Opcode, fields.c_str());
  ++decoded;
}
int wmain(int argc, wchar_t** argv)
{
  if (argc != 3 && (argc != 4 || std::wcscmp(argv[3], L"--inspect-system") != 0))
  {
    std::fprintf(stderr, "DecodeP1 input.etl NEW-output.jsonl [--inspect-system]\n");
    return 2;
  }
  inspect_system = argc == 4;
  if (GetFileAttributesW(argv[2]) != INVALID_FILE_ATTRIBUTES)
  {
    std::fprintf(stderr, "Refusing overwrite\n");
    return 2;
  }
  if (_wfopen_s(&output, argv[2], L"wb"))
    return 2;
  EVENT_TRACE_LOGFILEW logfile{};
  logfile.LogFileName = argv[1];
  logfile.ProcessTraceMode = PROCESS_TRACE_MODE_EVENT_RECORD | PROCESS_TRACE_MODE_RAW_TIMESTAMP;
  logfile.EventRecordCallback = Event;
  TRACEHANDLE trace = OpenTraceW(&logfile);
  if (trace == INVALID_PROCESSTRACE_HANDLE)
  {
    std::fclose(output);
    return 3;
  }
  const ULONG result = ProcessTrace(&trace, 1, nullptr, nullptr);
  CloseTrace(trace);
  std::fclose(output);
  std::printf("{\"status\":%lu,\"total\":%llu,\"decoded\":%llu,\"native_decode_errors\":%llu,"
              "\"events_lost\":%lu,\"buffers_lost\":%lu,\"qpc_frequency\":%lld}\n",
              result, total, decoded, errors, logfile.LogfileHeader.EventsLost,
              logfile.LogfileHeader.BuffersLost, logfile.LogfileHeader.PerfFreq.QuadPart);
  return result != ERROR_SUCCESS || errors != 0 || logfile.LogfileHeader.EventsLost != 0 ||
         logfile.LogfileHeader.BuffersLost != 0;
}