// SPDX-License-Identifier: Apache-2.0

// SPDX-FileCopyrightText: Copyright The WasmEdge Authors

#include "loader/loader.h"

#include "aot/version.h"

#include <algorithm>

#include <cstddef>

#include <fstream>

#include <limits>

#include <memory>

#include <system_error>

#include <utility>

#include <variant>

using namespace std::literals;

namespace WasmEdge {

namespace Loader {

// Load data from file path. See "include/loader/loader.h".

Expect<std::vector<Byte>>

Loader::loadFile(const std::filesystem::path &FilePath) {

  std::error_code EC;

  size_t FileSize = std::filesystem::file_size(FilePath, EC);

  if (EC) {

    spdlog::error(ErrCode::Value::IllegalPath);

    spdlog::error(ErrInfo::InfoFile(FilePath));

    return Unexpect(ErrCode::Value::IllegalPath);

  }

  std::ifstream Fin(FilePath, std::ios::in | std::ios::binary);

  if (!Fin) {

    spdlog::error(ErrCode::Value::IllegalPath);

    spdlog::error(ErrInfo::InfoFile(FilePath));

    return Unexpect(ErrCode::Value::IllegalPath);

  }

  std::vector<Byte> Buf(FileSize);

  size_t Index = 0;

  while (FileSize > 0) {

    const uint32_t BlockSize = static_cast<uint32_t>(

        std::min<size_t>(FileSize, std::numeric_limits<uint32_t>::max()));

    Fin.read(reinterpret_cast<char *>(Buf.data()) + Index, BlockSize);

    const uint32_t ReadCount = static_cast<uint32_t>(Fin.gcount());

    if (ReadCount != BlockSize) {

      if (Fin.eof()) {

        spdlog::error(ErrCode::Value::UnexpectedEnd);

        spdlog::error(ErrInfo::InfoLoading(ReadCount));

        spdlog::error(ErrInfo::InfoFile(FilePath));

        return Unexpect(ErrCode::Value::UnexpectedEnd);

      } else {

        spdlog::error(ErrCode::Value::ReadError);

        spdlog::error(ErrInfo::InfoLoading(ReadCount));

        spdlog::error(ErrInfo::InfoFile(FilePath));

        return Unexpect(ErrCode::Value::ReadError);

      }

    }

    Index += static_cast<size_t>(BlockSize);

    FileSize -= static_cast<size_t>(BlockSize);

  }

  return Buf;

}

// Parse module or component from file path. See "include/loader/loader.h".

Expect<std::variant<std::unique_ptr<AST::Component::Component>,

                    std::unique_ptr<AST::Module>>>

Loader::parseWasmUnit(const std::filesystem::path &FilePath) {

  std::lock_guard Lock(Mutex);

  // Set path and check the header.

  EXPECTED_TRY(FMgr.setPath(FilePath).map_error([&FilePath](auto E) {

    spdlog::error(E);

    spdlog::error(ErrInfo::InfoFile(FilePath));

    return E;

  }));

  auto ReportError = [&FilePath](auto E) {

    spdlog::error(ErrInfo::InfoFile(FilePath));

    return E;

  };

  switch (FMgr.getHeaderType()) {

  // Filter out the Windows .dll, macOS .dylib, or Linux .so AOT compiled

  // shared-library-WASM.

  case FileMgr::FileHeader::ELF:

  case FileMgr::FileHeader::DLL:

  case FileMgr::FileHeader::MachO_32:

  case FileMgr::FileHeader::MachO_64: {

    if (Conf.getRuntimeConfigure().getRunMode() != RunMode::AOT) {

      spdlog::error("Might an invalid wasm file"sv);

      spdlog::error(ErrCode::Value::MalformedMagic);

      spdlog::error(

          "    The AOT compiled WASM shared library is only loadable in the "

          "AOT run mode. Please use a normal WASM file, or set the run mode "

          "to AOT."sv);

      spdlog::error(ErrInfo::InfoFile(FilePath));

      return Unexpect(ErrCode::Value::MalformedMagic);

    }

    WASMType = InputType::SharedLibrary;

    FMgr.reset();

    std::shared_ptr<SharedLibrary> Library = std::make_shared<SharedLibrary>();

    EXPECTED_TRY(Library->load(FilePath).map_error(ReportError));

    EXPECTED_TRY(auto Version, Library->getVersion().map_error(ReportError));

    if (Version != AOT::kBinaryVersion) {

      spdlog::error(ErrInfo::InfoMismatch(AOT::kBinaryVersion, Version));

      spdlog::error(ErrInfo::InfoFile(FilePath));

      return Unexpect(ErrCode::Value::MalformedVersion);

    }

    EXPECTED_TRY(auto Code, Library->getWasm().map_error(ReportError));

    // Keep the library alive and load executable symbols.

    EXPECTED_TRY(FMgr.setCode(Code).map_error(ReportError));

    EXPECTED_TRY(auto Unit, loadUnit().map_error(ReportError));

    if (auto Ptr = std::get_if<std::unique_ptr<AST::Module>>(&Unit);

        likely(!!Ptr)) {

      EXPECTED_TRY(loadExecutable(**Ptr, Library).map_error(ReportError));

    } else {

      spdlog::error("Component Module is not supported in AOT."sv);

      spdlog::error(ErrInfo::InfoFile(FilePath));

      return Unexpect(ErrCode::Value::IllegalGrammar);

    }

    return Unit;

  }

  default: {

    // Universal WASM, WASM, or other cases. Load and parse the module directly.

    // The intrinsics-table pointer (if any executable is loaded) is patched

    // inside loadExecutable, so no symbol manipulation is needed here.

    WASMType = InputType::WASM;

    return loadUnit().map_error(ReportError);

  }

  }

}

// Parse module or component from byte code. See "include/loader/loader.h".

Expect<std::variant<std::unique_ptr<AST::Component::Component>,

                    std::unique_ptr<AST::Module>>>

Loader::parseWasmUnit(Span<const uint8_t> Code) {

  std::lock_guard Lock(Mutex);

  EXPECTED_TRY(FMgr.setCode(Code));

  switch (FMgr.getHeaderType()) {

  // Filter out the Windows .dll, macOS .dylib, or Linux .so AOT compiled

  // shared-library-WASM.

  case FileMgr::FileHeader::ELF:

  case FileMgr::FileHeader::DLL:

  case FileMgr::FileHeader::MachO_32:

  case FileMgr::FileHeader::MachO_64:

    spdlog::error("Might an invalid wasm file"sv);

    spdlog::error(ErrCode::Value::MalformedMagic);

    spdlog::error(

        "    The AOT compiled WASM shared library is not supported for loading "

        "from memory. Please use a normal WASM file, or load the AOT compiled "

        "WASM shared library from file in the AOT run mode."sv);

    return Unexpect(ErrCode::Value::MalformedMagic);

  default:

    break;

  }

  // For malformed header checking, handle in the module loading.

  WASMType = InputType::WASM;

  return loadUnit();

}

// Parse module from file path. See "include/loader/loader.h".

Expect<std::unique_ptr<AST::Module>>

Loader::parseModule(const std::filesystem::path &FilePath) {

  EXPECTED_TRY(auto ComponentOrModule, parseWasmUnit(FilePath));

  if (auto M = std::get_if<std::unique_ptr<AST::Module>>(&ComponentOrModule)) {

    return std::move(*M);

  }

  return Unexpect(ErrCode::Value::MalformedVersion);

}

// Parse module from byte code. See "include/loader/loader.h".

Expect<std::unique_ptr<AST::Module>>

Loader::parseModule(Span<const uint8_t> Code) {

  EXPECTED_TRY(auto ComponentOrModule, parseWasmUnit(Code));

  if (auto M = std::get_if<std::unique_ptr<AST::Module>>(&ComponentOrModule)) {

    return std::move(*M);

  }

  return Unexpect(ErrCode::Value::MalformedVersion);

}

// Load module or component unit. See "include/loader/loader.h".

Expect<std::variant<std::unique_ptr<AST::Component::Component>,

                    std::unique_ptr<AST::Module>>>

Loader::loadUnit() {

  EXPECTED_TRY(auto Preamble, loadPreamble());

  auto &[WasmMagic, Ver] = Preamble;

  if (Ver == ModuleVersion) {

    auto Mod = std::make_unique<AST::Module>();

    Mod->getMagic() = WasmMagic;

    Mod->getVersion() = Ver;

    if (Conf.getRuntimeConfigure().getRunMode() == RunMode::AOT) {

      EXPECTED_TRY(loadModuleAOT(Mod->getAOTSection()));

    }

    // Seek to the position after the binary header.

    FMgr.seek(8);

    EXPECTED_TRY(loadModule(*Mod));

    // Load library from AOT Section for the universal WASM case only when the

    // configured run mode is AOT.

    if (Conf.getRuntimeConfigure().getRunMode() == RunMode::AOT) {

      if (WASMType == InputType::UniversalWASM) {

        EXPECTED_TRY(loadUniversalWASM(*Mod));

      } else if (WASMType == InputType::WASM) {

        // AOT requested on a plain .wasm with no AOT artifact.

        spdlog::warn("AOT was requested but the input has no AOT artifact, "

                     "falling back to interpreter."sv);

      }

    }

    return Mod;

  } else if (Ver == ComponentVersion) {

    if (!Conf.hasProposal(Proposal::Component)) {

      return logNeedProposal(ErrCode::Value::MalformedVersion,

                             Proposal::Component, FMgr.getLastOffset(),

                             ASTNodeAttr::Component);

    }

    spdlog::warn("component model is an experimental proposal"sv);

    auto Comp = std::make_unique<AST::Component::Component>();

    Comp->getMagic() = WasmMagic;

    Comp->getVersion() = {Ver[0], Ver[1]};

    Comp->getLayer() = {Ver[2], Ver[3]};

    EXPECTED_TRY(loadComponent(*Comp));

    return Comp;

  } else {

    return logLoadError(ErrCode::Value::MalformedVersion, FMgr.getLastOffset(),

                        ASTNodeAttr::Component);

  }

}

// Serialize module into byte code. See "include/loader/loader.h".

Expect<std::vector<Byte>> Loader::serializeModule(const AST::Module &Mod) {

  return Ser.serializeModule(Mod);

}

// Helper function to set the function type for tag.

void Loader::setTagFunctionType(AST::TagSection &TagSec,

                                AST::ImportSection &ImportSec,

                                AST::TypeSection &TypeSec) {

  auto &TypeVec = TypeSec.getContent();

  for (auto &TgType : TagSec.getContent()) {

    auto TypeIdx = TgType.getTypeIdx();

    // Invalid type index would be checked during validation.

    if (TypeIdx < TypeVec.size()) {

      TgType.setDefType(&TypeVec[TypeIdx]);

    }

  }

  for (auto &Desc : ImportSec.getContent()) {

    if (Desc.getExternalType() == ExternalType::Tag) {

      auto &TgType = Desc.getExternalTagType();

      auto TypeIdx = TgType.getTypeIdx();

      // Invalid type index would be checked during validation.

      if (TypeIdx < TypeVec.size()) {

        TgType.setDefType(&TypeVec[TypeIdx]);

      }

    }

  }

}

} // namespace Loader

} // namespace WasmEdge