// Copyright 2026 Dolphin Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later

#include <algorithm>
#include <cstdlib>
#include <fstream>
#include <iostream>
#include <string>
#include <string_view>
#include <vector>

#include "Common/MsgHandler.h"
#include "Core/Core.h"
#include "Core/HW/Memmap.h"
#include "Core/HW/WII_IPC.h"
#include "Core/IOS/Starlet/ARMCore.h"
#include "Core/IOS/Starlet/BootstrapELF.h"
#include "Core/IOS/Starlet/StarletMemory.h"
#include "Core/System.h"
#include "StarOSPanicCheck.h"

namespace
{
using namespace StarletBootstrapProbe;

enum class ExpectedOutcome
{
  Idle,
  Panic,
  FatalData,
  UndefinedFault,
  Phase2
};

// Exit status of a run stopped by a Dolphin alert (1: failed expectation, 2: usage).
constexpr int ALERT_EXIT_STATUS = 3;

// Slices run once a StarOS panic path looks finished, to see that it stays so.
constexpr int PANIC_SETTLE_SLICES = 2;

// Dolphin's default handler shows an alert in a modal MessageBox on Windows, which blocks the
// probe until someone closes it. Report the alert on stderr and fail the run at once instead.
bool FailOnAlert(const char* caption, const char* text, bool, Common::MsgType)
{
  std::cout.flush();
  std::cerr << "Dolphin alert (" << caption << "): " << text << std::endl;
  std::_Exit(ALERT_EXIT_STATUS);
}

bool Run(const std::string& path, bool jit, bool mmu_faults, SBR1Mode sbr1,
         ExpectedOutcome expected)
{
  std::ifstream file(path, std::ios::binary | std::ios::ate);
  if (!file || file.tellg() <= 0 || file.tellg() > 16 * 1024 * 1024)
  {
    std::cerr << "Expected a readable Starlet ELF of at most 16 MiB: " << path << '\n';
    return false;
  }
  const size_t size = static_cast<size_t>(file.tellg());
  std::vector<u8> image(size);
  file.seekg(0);
  if (!file.read(reinterpret_cast<char*>(image.data()), size))
  {
    std::cerr << "Could not read Starlet ELF: " << path << '\n';
    return false;
  }

  Core::DeclareAsCPUThread();
  auto& system = Core::System::GetInstance();
  system.GetWiiIPC().Reset();
  IOS::LLE::StarletMemory memory(system);
  memory.PrepareBootstrap();
  IOS::LLE::BootstrapELFInfo info;
  std::string error;
  if (!IOS::LLE::LoadBootstrapELF(image, memory, &info, &error))
  {
    std::cerr << error << '\n';
    return false;
  }

  IOS::LLE::ARMCore core(memory);
  core.SetJitEnabled(jit);
  core.Reset(info.entry);
  core.SetBigEndian(true);
  // StarOS MMU-001: translation, domain, permission and alignment aborts (off by default).
  core.SetMMUFaultsEnabled(mmu_faults);
  constexpr u32 TRACE_MAGIC = 0x52455631;
  constexpr u32 TRACE_CAPACITY = 1024;
  auto& mem1 = system.GetMemory();
  const auto read_mem1 = [&mem1](u32 address) { return mem1.Read_U32(address); };
  const auto panic_unmet = [&] {
    return UnmetPanicCondition(memory.Read32(info.panic_state), memory.Read32(info.panic_code),
                               sbr1, read_mem1);
  };
  // StarOS's panic path writes no trace line. Print the trace published so far, for the
  // scenario's ordered checks, and the panic words.
  const auto report_panic = [&] {
    const u32 length = memory.Read32(info.trace) == TRACE_MAGIC ?
                           std::min(memory.Read32(info.trace + 4), TRACE_CAPACITY) :
                           0;
    for (u32 index = 0; index < length; ++index)
      std::cout << static_cast<char>(memory.Read8(info.trace + 8 + index));
    std::cout << "PC=0x" << std::hex << core.GetRegister(15) << std::dec
              << " instructions=" << core.GetExecutedInstructions() << '\n';
    std::cerr << "Starlet panic state " << memory.Read32(info.panic_state) << " code "
              << memory.Read32(info.panic_code) << '\n';
  };
  int panic_settled = 0;
  for (int slice = 0; slice < 512; ++slice)
  {
    core.SetIRQLine(system.GetWiiIPC().IsStarletIRQAsserted());
    core.SetFIQLine(system.GetWiiIPC().IsStarletFIQAsserted());
    core.RunCycles(4096);
    const u32 fault_code = memory.Read32(info.fault_code);
    if (fault_code != 0)
    {
      std::cerr << "Starlet exception " << fault_code << " LR=" << std::hex
                << memory.Read32(info.fault_lr) << " SPSR=" << memory.Read32(info.fault_spsr)
                << " PC=" << core.GetRegister(15) << std::dec << '\n';
      return expected == ExpectedOutcome::UndefinedFault && fault_code == 1 &&
             memory.Read32(info.fault_lr) != 0 && memory.Read32(info.fault_spsr) != 0;
    }
    // StarOS's panic path sets its guard word first, then its code, then publishes the SBR1
    // record when there is one, and halts. An expected panic passes once all of that holds
    // (UnmetPanicCondition) and still holds PANIC_SETTLE_SLICES slices later.
    if (info.panic_state != 0 && memory.Read32(info.panic_state) != 0)
    {
      if (expected != ExpectedOutcome::Panic)
      {
        report_panic();
        return false;
      }
      if (!panic_unmet().empty())
      {
        panic_settled = 0;
        continue;
      }
      if (++panic_settled <= PANIC_SETTLE_SLICES)
        continue;
      report_panic();
      return true;
    }
    if (memory.Read32(info.trace) != TRACE_MAGIC)
      continue;
    const u32 length = memory.Read32(info.trace + 4);
    if (length > TRACE_CAPACITY)
    {
      std::cerr << "Invalid REV_TRACE length: " << length << '\n';
      return false;
    }
    std::string trace(length, '\0');
    for (u32 index = 0; index < length; ++index)
      trace[index] = static_cast<char>(memory.Read8(info.trace + 8 + index));
    if (trace.find("REV:BOOT:IDLE\n") == std::string::npos &&
        trace.find("REV:PANIC") == std::string::npos &&
        trace.find("REV:FATAL") == std::string::npos)
    {
      continue;
    }
    std::cout << trace;
    std::cout << "PC=0x" << std::hex << core.GetRegister(15) << std::dec
              << " instructions=" << core.GetExecutedInstructions() << '\n';
    const bool early_startup_ok = trace.find("REV:BOOT:ENTRY\n") != std::string::npos &&
                                  trace.find("REV:BOOT:BSS_OK\n") != std::string::npos;
    if (expected == ExpectedOutcome::FatalData)
    {
      return early_startup_ok && trace.find("REV:FATAL:DATA\n") != std::string::npos &&
             trace.find("REV:BOOT:DATA_OK\n") == std::string::npos;
    }
    const bool startup_ok = early_startup_ok &&
                            trace.find("REV:BOOT:DATA_OK\n") != std::string::npos &&
                            trace.find("REV:BOOT:STACK_OK\n") != std::string::npos &&
                            trace.find("REV:BOOT:RUST\n") != std::string::npos;
    if (expected == ExpectedOutcome::Phase2)
    {
      const std::string_view required[] = {
          "REV:P2:START\n", "ARCH PASS\n",           "CRITICAL PASS\n",
          "TIMER PASS\n",   "MONOTONIC PASS\n",      "MEM PASS\n",
          "IRQ PASS\n",     "BARRIER PASS\n",        "LOGGING PASS\n",
          "REV:P2:PASS\n",  "REV:P2:KERNEL_READY\n", "REV:BOOT:IDLE\n"};
      bool phase2_ok = true;
      for (const std::string_view marker : required)
        phase2_ok &= trace.find(marker) != std::string::npos;
      return startup_ok && phase2_ok && trace.find(" FAIL\n") == std::string::npos;
    }
    const bool outcome_ok =
        expected == ExpectedOutcome::Panic ?
            trace.find("REV:PANIC") != std::string::npos :
            expected == ExpectedOutcome::Idle && trace.find("REV:BOOT:IDLE\n") != std::string::npos;
    return startup_ok && outcome_ok;
  }
  if (info.panic_state != 0 && memory.Read32(info.panic_state) != 0)
  {
    report_panic();
    const std::string unmet = panic_unmet();
    std::cerr << "StarOS panic path unfinished after 2097152 ARM cycles: "
              << (unmet.empty() ? "it ended inside the settle slices" : unmet) << '\n';
    return false;
  }
  std::cerr << "No terminal bootstrap marker after 2097152 ARM cycles, PC=0x" << std::hex
            << core.GetRegister(15) << std::dec << '\n';
  return false;
}
}  // namespace

int main(int argc, char** argv)
{
  Common::RegisterMsgAlertHandler(FailOnAlert);
  if (argc < 2 || argc > 6)
  {
    std::cerr << "Usage: StarletBootstrapProbe <ELF> [--jit] [--mmu-faults] "
                 "[--sbr1-record|--sbr1-absent] "
                 "[--expect-panic|--expect-fatal-data|--expect-undefined-fault|--expect-phase2]\n";
    return 2;
  }
  bool jit = false;
  bool mmu_faults = false;
  SBR1Mode sbr1 = SBR1Mode::None;
  ExpectedOutcome expected = ExpectedOutcome::Idle;
  bool outcome_selected = false;
  for (int index = 2; index < argc; ++index)
  {
    const std::string_view option = argv[index];
    if (option == "--jit")
      jit = true;
    else if (option == "--mmu-faults")
      mmu_faults = true;
    else if (option == "--sbr1-record" || option == "--sbr1-absent")
    {
      if (sbr1 != SBR1Mode::None)
      {
        std::cerr << "Select only one SBR1 mode\n";
        return 2;
      }
      sbr1 = option == "--sbr1-record" ? SBR1Mode::Record : SBR1Mode::Absent;
    }
    else if (option == "--expect-panic" || option == "--expect-fatal-data" ||
             option == "--expect-undefined-fault" || option == "--expect-phase2")
    {
      if (outcome_selected)
      {
        std::cerr << "Select only one expected outcome\n";
        return 2;
      }
      outcome_selected = true;
      expected = option == "--expect-panic"           ? ExpectedOutcome::Panic :
                 option == "--expect-fatal-data"      ? ExpectedOutcome::FatalData :
                 option == "--expect-undefined-fault" ? ExpectedOutcome::UndefinedFault :
                                                        ExpectedOutcome::Phase2;
    }
    else
    {
      std::cerr << "Unknown option: " << option << '\n';
      return 2;
    }
  }

  // The Starlet shares MEM1 and MEM2 with Broadway. Back them as on a retail Wii (24 and 64 MiB,
  // zeroed): without them, any Starlet access there, such as StarOS reading its SBR1 record
  // header at 0x00200000, is an access to unmapped memory and raises an alert.
  auto& system = Core::System::GetInstance();
  system.SetIsWii(true);
  system.GetMemory().Init();
  auto& memory = system.GetMemory();
  if (sbr1 == SBR1Mode::Record)
  {
    // As the Broadway loader and the ARM relay leave StarOS's SBR1 boot record before the image
    // runs (StarOS docs/contracts/wii-dev-boot.md): header, the relay at its last step, EXI
    // channel 1 given to the Starlet, the magic written last.
    memory.Write_U32(SBR1_VERSION, SBR1_BASE + 0x04);
    memory.Write_U32(SBR1_SIZE, SBR1_BASE + 0x08);
    memory.Write_U32(SBR1_EXI_STARLET, SBR1_BASE + SBR1_EXI_OWNER);
    memory.Write_U32(SBR1_RELAY_JUMPING, SBR1_BASE + SBR1_RELAY_STATUS);
    memory.Write_U32(SBR1_MAGIC, SBR1_BASE);
  }
  const bool passed = Run(argv[1], jit, mmu_faults, sbr1, expected);
  if (sbr1 != SBR1Mode::None)
  {
    // The record's summary after the run; with --sbr1-absent every word must still be zero (an
    // expected panic fails otherwise).
    std::cerr << std::hex << "SBR1 magic 0x" << memory.Read_U32(SBR1_BASE) << std::dec
              << " state " << memory.Read_U32(SBR1_BASE + SBR1_STARLET_STATE) << " reason "
              << memory.Read_U32(SBR1_BASE + SBR1_FATAL_REASON) << " owner "
              << memory.Read_U32(SBR1_BASE + SBR1_EXI_OWNER) << " fault "
              << memory.Read_U32(SBR1_BASE + SBR1_FAULT_CODE) << " ring "
              << memory.Read_U32(SBR1_BASE + SBR1_RING_LENGTH) << " dropped "
              << memory.Read_U32(SBR1_BASE + SBR1_RING_DROPPED);
    u32 written = 0;
    for (u32 offset = 0; offset < SBR1_SIZE; offset += 4)
      written += memory.Read_U32(SBR1_BASE + offset) != 0;
    std::cerr << " nonzero_words " << written << '\n';
  }
  system.GetMemory().Shutdown();
  return passed ? 0 : 1;
}