#include <catch2/catch_all.hpp>

#include <clang/ASTMatchers/ASTMatchers.h>
#include <clang/ASTMatchers/ASTMatchFinder.h>
#include <clang/Basic/Version.h>
#include <clang/Frontend/CompilerInstance.h>
#include <clang/Tooling/Tooling.h>

#include <interface.h>

#include <filesystem>
#include <fstream>
#include <string_view>

#include "common.h"

/**
 * This class parses its input code and stores it alongside its AST representation.
 *
 * Use this with HasASTMatching in Catch2's CHECK_THAT/REQUIRE_THAT macros.
 */
struct SourceWithAST {
  std::string code;
  std::unique_ptr<clang::ASTUnit> ast;

  SourceWithAST(std::string_view input, bool silent_compile = false);
};

std::ostream& operator<<(std::ostream& os, const SourceWithAST& ast) {
  os << ast.code;

  // Additionally, change this to true to print the full AST on test failures
  const bool print_ast = false;
  if (print_ast) {
    for (auto it = ast.ast->top_level_begin(); it != ast.ast->top_level_end(); ++it) {
      // Skip header declarations
      if (!ast.ast->isInMainFileID((*it)->getBeginLoc())) {
        continue;
      }

      auto llvm_os = llvm::raw_os_ostream {os};
      (*it)->dump(llvm_os);
    }
  }
  return os;
}

struct Fixture {
  Fixture() {
    tmpdir = std::string {P_tmpdir} + "/thunkgentestXXXXXX";
    if (!mkdtemp(tmpdir.data())) {
      std::abort();
    }
    std::filesystem::create_directory(tmpdir);
    output_filenames = {
      tmpdir + "/thunkgen_guest",
      tmpdir + "/thunkgen_host",
    };
  }

  ~Fixture() {
    std::filesystem::remove_all(tmpdir);
  }

  struct GenOutput {
    SourceWithAST guest;
    SourceWithAST host;
  };

  /**
   * Runs the given given code through the thunk generator and verifies the output compiles.
   *
   * Input code with common definitions (types, functions, ...) should be specified in "prelude".
   * It will be prepended to "code" before processing and also to the generator output.
   */
  SourceWithAST run_thunkgen_guest(std::string_view prelude, std::string_view code, bool silent = false);
  SourceWithAST run_thunkgen_host(std::string_view prelude, std::string_view code, GuestABI = GuestABI::X86_64, bool silent = false);
  GenOutput run_thunkgen(std::string_view prelude, std::string_view code, bool silent = false);

  const std::string libname = "libtest";
  std::string tmpdir;
  OutputFilenames output_filenames;
};

using namespace clang::ast_matchers;

class MatchCallback : public MatchFinder::MatchCallback {
  bool success = false;

  using CheckFn = std::function<bool(const MatchFinder::MatchResult&)>;
  std::vector<CheckFn> binding_checks;

public:
  template<typename NodeType>
  void check_binding(std::string_view binding_name, bool (*check_fn)(const NodeType*)) {
    // Decorate the given check with node extraction and wrap it in a type-erased interface
    binding_checks.push_back([check_fn, binding_name = std::string(binding_name)](const MatchFinder::MatchResult& result) {
      if (auto node = result.Nodes.getNodeAs<NodeType>(binding_name.c_str())) {
        return check_fn(node);
      }
      return false;
    });
  }

  void run(const MatchFinder::MatchResult& result) override {
    success = true; // NOTE: If there are no callbacks, this signals that the match was found at all

    for (auto& binding_check : binding_checks) {
      success = success && binding_check(result);
    }
  }

  bool matched() const noexcept {
    return success;
  }
};

/**
 * This class connects the libclang AST to Catch2 test matchers, allowing for
 * code compiled via SourceWithAST objects to be pattern-matched using the
 * libclang ASTMatcher API.
 */
template<typename ClangMatcher>
class HasASTMatching : public Catch::Matchers::MatcherBase<SourceWithAST> {
  ClangMatcher matcher;
  MatchCallback callback;

public:
  HasASTMatching(const ClangMatcher& matcher_)
    : matcher(matcher_) {}

  template<typename NodeT>
  HasASTMatching& check_binding(std::string_view binding_name, bool (*check_fn)(const NodeT*)) {
    callback.check_binding(binding_name, check_fn);
    return *this;
  }

  bool match(const SourceWithAST& code) const override {
    MatchCallback result = callback;
    clang::ast_matchers::MatchFinder finder;
    finder.addMatcher(matcher, &result);
    finder.matchAST(code.ast->getASTContext());
    return result.matched();
  }

  std::string describe() const override {
    std::ostringstream ss;
    ss << "should compile and match the given AST pattern";
    return ss.str();
  }
};

HasASTMatching<DeclarationMatcher> matches(const DeclarationMatcher& matcher_) {
  return HasASTMatching<DeclarationMatcher>(matcher_);
}

HasASTMatching<StatementMatcher> matches(const StatementMatcher& matcher_) {
  return HasASTMatching<StatementMatcher>(matcher_);
}

/**
 * Catch matcher that checks if a tested C++ source defines a function with the given name
 */
class DefinesPublicFunction : public HasASTMatching<DeclarationMatcher> {
  std::string function_name;

public:
  DefinesPublicFunction(std::string_view name)
    : HasASTMatching(functionDecl(hasName(name)))
    , function_name(name) {}

  std::string describe() const override {
    std::ostringstream ss;
    ss << "should define and export a function called \"" + function_name + "\"";
    return ss.str();
  }
};

SourceWithAST::SourceWithAST(std::string_view input, bool silent_compile)
  : code(input) {
  // Call run_tool with a ToolAction that assigns this->ast

  struct ToolAction : clang::tooling::ToolAction {
    std::unique_ptr<clang::ASTUnit>& ast;

    ToolAction(std::unique_ptr<clang::ASTUnit>& ast_)
      : ast(ast_) {}

    bool runInvocation(std::shared_ptr<clang::CompilerInvocation> invocation, clang::FileManager* files,
                       std::shared_ptr<clang::PCHContainerOperations> pch, clang::DiagnosticConsumer* diag_consumer) override {
      auto diagnostics = clang::CompilerInstance::createDiagnostics(&invocation->getDiagnosticOpts(), diag_consumer, false);
      ast = clang::ASTUnit::LoadFromCompilerInvocation(invocation, std::move(pch), std::move(diagnostics), files);
      return (ast != nullptr);
    }
  } tool_action {ast};

  run_tool(tool_action, code, silent_compile);
}

/**
 * Generates guest thunk library code from the given input
 */
SourceWithAST Fixture::run_thunkgen_guest(std::string_view prelude, std::string_view code, bool silent) {
  const std::string full_code = std::string {prelude} + std::string {code};

  // These tests don't deal with data layout differences, so just run data
  // layout analysis with host configuration
  auto data_layout_analysis_factory = std::make_unique<AnalyzeDataLayoutActionFactory>();
  run_tool(*data_layout_analysis_factory, full_code, silent);
  auto& data_layout = data_layout_analysis_factory->GetDataLayout();

  run_tool(std::make_unique<GenerateThunkLibsActionFactory>(libname, output_filenames, data_layout), full_code, silent);

  std::string result = "#include <cstdint>\n"
                       "#define MAKE_THUNK(lib, name, hash) extern \"C\" int fexthunks_##lib##_##name(void*);\n"
                       "template<typename>\n"
                       "struct callback_thunk_defined;\n"
                       "#define MAKE_CALLBACK_THUNK(name, sig, hash) template<> struct callback_thunk_defined<sig> {};\n"
                       "#define FEX_PACKFN_LINKAGE\n"
                       "template<typename Target>\n"
                       "Target *MakeHostTrampolineForGuestFunction(uint8_t HostPacker[32], void (*)(uintptr_t, void*), Target*);\n"
                       "template<typename Target>\n"
                       "Target *AllocateHostTrampolineForGuestFunction(Target*);\n";
  const auto& filename = output_filenames.guest;
  {
    std::ifstream file(filename);
    const auto current_size = result.size();
    const auto new_data_size = std::filesystem::file_size(filename);
    result.resize(result.size() + new_data_size);
    file.read(result.data() + current_size, result.size());
  }
  return SourceWithAST {std::string {prelude} + result};
}

/**
 * Generates host thunk library code from the given input
 */
SourceWithAST Fixture::run_thunkgen_host(std::string_view prelude, std::string_view code, GuestABI guest_abi, bool silent) {
  const std::string full_code = std::string {prelude} + std::string {code};

  // These tests don't deal with data layout differences, so just run data
  // layout analysis with host configuration
  auto data_layout_analysis_factory = std::make_unique<AnalyzeDataLayoutActionFactory>();
  run_tool(*data_layout_analysis_factory, full_code, silent, guest_abi);
  auto& data_layout = data_layout_analysis_factory->GetDataLayout();

  run_tool(std::make_unique<GenerateThunkLibsActionFactory>(libname, output_filenames, data_layout), full_code, silent);

  std::string result =
    "#include <array>\n"
    "#include <cstdint>\n"
    "#include <cstring>\n"
    "#include <dlfcn.h>\n"
    "#include <type_traits>\n"
    "template<typename Fn>\n"
    "struct function_traits;\n"
    "template<typename Result, typename Arg>\n"
    "struct function_traits<Result(*)(Arg)> {\n"
    "    using result_t = Result;\n"
    "    using arg_t = Arg;\n"
    "};\n"
    "template<auto Fn>\n"
    "static typename function_traits<decltype(Fn)>::result_t\n"
    "fexfn_type_erased_unpack(void* argsv) {\n"
    "    using args_t = typename function_traits<decltype(Fn)>::arg_t;\n"
    "    return Fn(reinterpret_cast<args_t>(argsv));\n"
    "}\n"
    "#define LOAD_INTERNAL_GUESTPTR_VIA_CUSTOM_ABI(arg)\n"
    "struct GuestcallInfo {\n"
    "  uintptr_t HostPacker;\n"
    "  void (*CallCallback)(uintptr_t, uintptr_t, void*);\n"
    "  uintptr_t GuestUnpacker;\n"
    "  uintptr_t GuestTarget;\n"
    "};\n"
    "struct ParameterAnnotations {};\n"
    "template<typename, typename...>\n"
    "struct GuestWrapperForHostFunction {\n"
    "  template<ParameterAnnotations...> static void Call(void*);\n"
    "};\n"
    "struct ExportEntry { uint8_t* sha256; void(*fn)(void *); };\n"
    "void *dlsym_default(void* handle, const char* symbol);\n"
    "template<typename T> inline constexpr bool has_compatible_data_layout = std::is_integral_v<T> || std::is_enum_v<T>;\n"
    "template<typename T>\n"
    "struct guest_layout {\n"
    "  T data;\n"
    "};\n"
    "\n"
    "template<typename T>\n"
    "struct guest_layout<T*> {\n"
    "#ifdef IS_32BIT_THUNK\n"
    "  using type = uint32_t;\n"
    "#else\n"
    "  using type = uint64_t;\n"
    "#endif\n"
    "  type data;\n"
    "};\n"
    "\n"
    "template<typename T>\n"
    "struct host_layout {\n"
    "  T data;\n"
    "\n"
    "  explicit host_layout(const guest_layout<T>&);\n"
    "  template<typename U> explicit host_layout(const guest_layout<U>&) requires (std::is_integral_v<U> && sizeof(U) <= sizeof(T) && "
    "std::is_convertible_v<T, U> && std::is_signed_v<T> == std::is_signed_v<U>);\n"
    "};\n"
    "\n"
    "template<typename T> constexpr bool is_long = std::is_same_v<T, long> || std::is_same_v<T, unsigned long>;\n"
    "template<typename T> constexpr bool is_longlong = std::is_same_v<T, long long> || std::is_same_v<T, unsigned long long>;\n"
    "template<typename T>\n"
    "struct host_layout<T*> {\n"
    "  T* data;\n"
    "  explicit host_layout(const guest_layout<T*>&);\n"
    "  template<typename U> explicit host_layout(const guest_layout<U*>&) requires (std::is_integral_v<U> && sizeof(U) == sizeof(long) && "
    "sizeof(long) == 8 && is_long<std::remove_cv_t<T>> && std::is_convertible_v<T, U> && std::is_signed_v<T> == std::is_signed_v<U>);\n"
    "  template<typename U> explicit host_layout(const guest_layout<U*>&) requires (std::is_integral_v<U> && sizeof(U) == sizeof(long "
    "long) && is_longlong<std::remove_cv_t<T>> && std::is_convertible_v<T, U> && std::is_signed_v<T> == std::is_signed_v<U>);\n"
    "  template<typename U> explicit host_layout(const guest_layout<U*>&) requires (std::is_same_v<std::remove_cv_t<T>, char> && "
    "std::is_integral_v<U> && std::is_convertible_v<T, U> && sizeof(U) == 1);\n"
    "  template<typename U> explicit host_layout(const guest_layout<U*>&) requires (std::is_same_v<std::remove_cv_t<T>, wchar_t> && "
    "std::is_integral_v<U> && std::is_convertible_v<T, U> && sizeof(U) == sizeof(wchar_t));\n"
    "};\n"
    "\n"
    "template<typename T> struct host_to_guest_convertible {\n"
    "  operator guest_layout<T>();\n"
    "  operator guest_layout<const unsigned long long*>() const requires(std::is_same_v<T, const unsigned long*>);\n"
    "  operator guest_layout<const uint8_t*>() const requires(std::is_same_v<T, const char*>);\n"
    "  operator guest_layout<uint8_t*>() const requires(std::is_same_v<T, char*>);\n"
    "  operator guest_layout<uint32_t*>() const requires(std::is_same_v<T, wchar_t*>);\n"
    "  template<typename U> operator guest_layout<U>() const requires (std::is_integral_v<U> && sizeof(U) == sizeof(T) && "
    "std::is_convertible_v<T, U> && std::is_signed_v<T> == std::is_signed_v<U>);\n"
    "#if IS_32BIT_THUNK\n"
    "  operator guest_layout<uint32_t>() const requires(std::is_same_v<T, size_t>);\n"
    "#endif\n"
    "};\n"
    "\n"
    "template<typename T, typename GuestT>\n"
    "struct repack_wrapper {};\n"
    "template<typename T, typename GuestT>\n"
    "repack_wrapper<T, GuestT> make_repack_wrapper(guest_layout<GuestT>& orig_arg);\n"
    "template<typename T> host_to_guest_convertible<T> to_guest(const host_layout<T>& from);\n"
    "template<typename F> void FinalizeHostTrampolineForGuestFunction(F*);\n"
    "template<typename F> void FinalizeHostTrampolineForGuestFunction(guest_layout<F*>);\n"
    "template<typename T> T& unwrap_host(host_layout<T>&);\n"
    "template<typename T, typename GuestT> T* unwrap_host(repack_wrapper<T*, GuestT>&);\n"
    "template<typename T> const host_layout<T>& to_host_layout(const T& t);\n";

  auto& filename = output_filenames.host;
  {
    std::ifstream file(filename);
    const auto prelude_size = result.size();
    const auto new_data_size = std::filesystem::file_size(filename);
    result.resize(result.size() + new_data_size);
    file.read(result.data() + prelude_size, result.size());

    // Force all functions to be non-static, since having to define them
    // would add a lot of noise to simple tests.
    while (true) {
      auto pos = result.find("static ", prelude_size);
      if (pos == std::string::npos) {
        break;
      }
      result.replace(pos, 6, "      "); // Replace "static" with 6 spaces (avoiding reallocation)
    }
  }
  return SourceWithAST {std::string {prelude} + result, silent};
}

Fixture::GenOutput Fixture::run_thunkgen(std::string_view prelude, std::string_view code, bool silent) {
  return {run_thunkgen_guest(prelude, code, silent), run_thunkgen_host(prelude, code, GuestABI::X86_64, silent)};
}

#if CLANG_VERSION_MAJOR <= 15
// Old clang versions require an explicit "struct" prefix
#define CLANG_STRUCT_PREFIX "struct "
#define asStructString(name) asString(CLANG_STRUCT_PREFIX name)
#else
#define CLANG_STRUCT_PREFIX
#define asStructString(name) asString(name)
#endif

TEST_CASE_METHOD(Fixture, "Trivial") {
  const auto output = run_thunkgen("", "#include <thunks_common.h>\n"
                                       "void func();\n"
                                       "template<auto> struct fex_gen_config {};\n"
                                       "template<> struct fex_gen_config<func> {};\n");

  // Guest code
  CHECK_THAT(output.guest, DefinesPublicFunction("func"));

  CHECK_THAT(output.guest, matches(functionDecl(hasName("fexfn_pack_func"), returns(asString("void")), parameterCountIs(0))));

  // Host code
  CHECK_THAT(output.host,
             matches(varDecl(hasName("exports"), hasType(constantArrayType(hasElementType(asStructString("ExportEntry")), hasSize(2))),
                             hasInitializer(initListExpr(
                               hasInit(0, expr()), hasInit(1, initListExpr(hasInit(0, implicitCastExpr()), hasInit(1, implicitCastExpr())))))
                             // TODO: check null termination
                             )));
}

// Unknown annotations trigger an error
TEST_CASE_METHOD(Fixture, "UnknownAnnotation") {
  REQUIRE_THROWS(run_thunkgen("void func();\n",
                              "struct invalid_annotation {};\n"
                              "template<auto> struct fex_gen_config {};\n"
                              "template<> struct fex_gen_config<func> : invalid_annotation {};\n",
                              true));

  REQUIRE_THROWS(run_thunkgen("void func();\n",
                              "template<auto> struct fex_gen_config {};\n"
                              "template<> struct fex_gen_config<func> { int invalid_field_annotation; };\n",
                              true));
}

TEST_CASE_METHOD(Fixture, "VersionedLibrary") {
  const auto output = run_thunkgen_host("", "template<auto> struct fex_gen_config { int version = 123; };\n");

  CHECK_THAT(output, matches(callExpr(callee(functionDecl(hasName("dlopen"))), hasArgument(0, stringLiteral().bind("libname"))))
                       .check_binding(
                         "libname", +[](const clang::StringLiteral* lit) { return lit->getString().endswith(".so.123"); }));
}

TEST_CASE_METHOD(Fixture, "FunctionPointerViaType") {
  const auto output = run_thunkgen("", "template<typename> struct fex_gen_type {};\n"
                                       "template<> struct fex_gen_type<int(char, char)> {};\n");

  // Guest should apply MAKE_CALLBACK_THUNK to this signature
  CHECK_THAT(output.guest, matches(classTemplateSpecializationDecl(
                             // Should have signature matching input function
                             hasName("callback_thunk_defined"), hasTemplateArgument(0, refersToType(asString("int (char, char)"))))));

  // Host should export the unpacking function for callback arguments
  CHECK_THAT(output.host,
             matches(varDecl(hasName("exports"), hasType(constantArrayType(hasElementType(asStructString("ExportEntry")), hasSize(2))),
                             hasInitializer(hasDescendant(declRefExpr(
                               to(cxxMethodDecl(hasName("Call"), ofClass(hasName("GuestWrapperForHostFunction"))).bind("funcptr")))))))
               .check_binding(
                 "funcptr", +[](const clang::CXXMethodDecl* decl) {
                   auto parent = llvm::cast<clang::ClassTemplateSpecializationDecl>(decl->getParent());
                   return parent->getTemplateArgs().get(0).getAsType().getAsString() == "int (unsigned char, unsigned char)";
                 }));
}

// Parameter is a function pointer
TEST_CASE_METHOD(Fixture, "FunctionPointerParameter") {
  const auto output = run_thunkgen("", "void func(int (*funcptr)(char, char));\n"
                                       "template<auto> struct fex_gen_config {};\n"
                                       "template<> struct fex_gen_config<func> {};\n");

  CHECK_THAT(output.guest, matches(functionDecl(
                             // Should have signature matching input function
                             hasName("fexfn_pack_func"), returns(asString("void")), parameterCountIs(1),
                             hasParameter(0, hasType(asString("int (*)(char, char)"))))));

  // Host packing function should call FinalizeHostTrampolineForGuestFunction on the argument
  CHECK_THAT(output.host,
             matches(functionDecl(hasName("fexfn_unpack_libtest_func"), hasDescendant(callExpr(callee(functionDecl(hasName("FinalizeHostTra"
                                                                                                                           "mpolineForGuest"
                                                                                                                           "Function"))),
                                                                                               hasArgument(0, expr().bind("funcptr"))))))
               .check_binding(
                 "funcptr", +[](const clang::Expr* funcptr) {
                   // Check that the argument type matches the function pointer
                   return funcptr->getType().getAsString() == "guest_layout<int (*)(char, char)>";
                 }));

  // Host should export the unpacking function for function pointer arguments
  CHECK_THAT(output.host,
             matches(varDecl(hasName("exports"), hasType(constantArrayType(hasElementType(asStructString("ExportEntry")), hasSize(3))),
                             hasInitializer(hasDescendant(declRefExpr(to(cxxMethodDecl(hasName("Call"), ofClass(hasName("GuestWrapperForHos"
                                                                                                                        "tFunctio"
                                                                                                                        "n"))))))))));
}

TEST_CASE_METHOD(Fixture, "MultipleParameters") {
  const std::string prelude = "struct TestStruct { int member; };\n";

  auto output = run_thunkgen(prelude, "void func(int arg, char, unsigned long, TestStruct);\n"
                                      "template<auto> struct fex_gen_config {};\n"
                                      "template<> struct fex_gen_config<func> {};\n");

  // Guest code
  CHECK_THAT(output.guest, DefinesPublicFunction("func"));

  CHECK_THAT(output.guest, matches(functionDecl(hasName("fexfn_pack_func"), returns(asString("void")), parameterCountIs(4),
                                                hasParameter(0, hasType(asString("int"))), hasParameter(1, hasType(asString("char"))),
                                                hasParameter(2, hasType(asString("unsigned long"))),
                                                hasParameter(3, hasType(asStructString("TestStruct"))))));

  // Host code
  CHECK_THAT(output.host,
             matches(varDecl(hasName("exports"), hasType(constantArrayType(hasElementType(asStructString("ExportEntry")), hasSize(2))),
                             hasInitializer(initListExpr(
                               hasInit(0, expr()), hasInit(1, initListExpr(hasInit(0, implicitCastExpr()), hasInit(1, implicitCastExpr())))))
                             // TODO: check null termination
                             )));

  CHECK_THAT(
    output.host,
    matches(functionDecl(
      hasName("fexfn_unpack_libtest_func"),
      // Packed argument struct should contain all parameters
      parameterCountIs(1),
      hasParameter(0, hasType(pointerType(pointee(hasUnqualifiedDesugaredType(recordType(hasDeclaration(decl(
                        has(fieldDecl(hasType(asString("guest_layout<int32_t>")))), has(fieldDecl(hasType(asString("guest_layout<uint8_t>")))),
                        has(fieldDecl(hasType(asString("guest_layout<uint64_t>")))),
                        has(fieldDecl(hasType(asString("guest_layout<" CLANG_STRUCT_PREFIX "TestStruct>")))))))))))))));
}

// Returning a function pointer should trigger an error unless an annotation is provided
TEST_CASE_METHOD(Fixture, "ReturnFunctionPointer") {
  const std::string prelude = "using funcptr = void (*)(char, char);\n";

  REQUIRE_THROWS(run_thunkgen_guest(prelude,
                                    "funcptr func(int);\n"
                                    "template<auto> struct fex_gen_config {};\n"
                                    "template<> struct fex_gen_config<func> {};\n",
                                    true));

  REQUIRE_NOTHROW(run_thunkgen_guest(prelude, "#include <thunks_common.h>\n"
                                              "funcptr func(int);\n"
                                              "template<auto> struct fex_gen_config {};\n"
                                              "template<> struct fex_gen_config<func> : fexgen::returns_guest_pointer {};\n"));
}

TEST_CASE_METHOD(Fixture, "VariadicFunction") {
  const std::string prelude = "void func(int arg, ...);\n";

  const auto output = run_thunkgen_guest(prelude, "template<auto> struct fex_gen_config {};\n"
                                                  "template<> struct fex_gen_config<func> {\n"
                                                  "  using uniform_va_type = char;\n"
                                                  "};\n");

  CHECK_THAT(output, matches(functionDecl(hasName("fexfn_pack_func_internal"), returns(asString("void")), parameterCountIs(3),
                                          hasParameter(0, hasType(asString("int"))), hasParameter(1, hasType(asString("unsigned long"))),
                                          hasParameter(2, hasType(pointerType(pointee(asString("char"))))))));
}

// Variadic functions without annotation trigger an error
TEST_CASE_METHOD(Fixture, "VariadicFunctionsWithoutAnnotation") {
  REQUIRE_THROWS(run_thunkgen_guest("void func(int arg, ...);\n",
                                    "template<auto> struct fex_gen_config {};\n"
                                    "template<> struct fex_gen_config<func> {};\n",
                                    true));
}

// Tests generation of guest_layout/host_layout wrappers and related helpers
TEST_CASE_METHOD(Fixture, "LayoutWrappers") {
  auto guest_abi = GENERATE(GuestABI::X86_32, GuestABI::X86_64);
  INFO(guest_abi);

  const auto host_layout_is_trivial =
    matches(classTemplateSpecializationDecl(hasName("host_layout"), hasAnyTemplateArgument(refersToType(asString("struct A"))),
                                            has(fieldDecl(hasName("data"), hasType(hasCanonicalType(asString("struct A")))))));
  const auto layout_undefined = [](const char* type) {
    return matches(classTemplateSpecializationDecl(hasName(type), hasAnyTemplateArgument(refersToType(asString("struct A")))).bind("layout"))
      .check_binding(
        "layout", +[](const clang::ClassTemplateSpecializationDecl* decl) { return !decl->isCompleteDefinition(); });
  };
  const auto guest_converter_defined = matches(functionDecl(
    hasName("to_guest"),
    // Parameter is a host_layout<A> (ignoring qualifiers and references)
    hasParameter(
      0, hasType(references(classTemplateSpecializationDecl(hasName("host_layout"), hasAnyTemplateArgument(refersToType(asString("struct "
                                                                                                                                 "A"))))))),
    // Return value is a guest_layout<A>
    returns(asString("guest_layout<" CLANG_STRUCT_PREFIX "A>"))));
  const auto guest_converter_undefined = matches(functionDecl(
    hasName("to_guest"),
    // Parameter is a host_layout<A> (ignoring qualifiers and references)
    hasParameter(
      0, hasType(references(classTemplateSpecializationDecl(hasName("host_layout"), hasAnyTemplateArgument(refersToType(asString("struct "
                                                                                                                                 "A"))))))),
    isDeleted()));

  const std::string code = "template<typename> struct fex_gen_type {};\n"
                           "template<> struct fex_gen_type<A> {};\n";

  // For fully compatible types, both guest_layout and host_layout directly
  // reference the original struct
  SECTION("Fully compatible type") {
    const char* struct_def = "struct A { int a; int b; };\n";
    const auto output = run_thunkgen_host(struct_def, code, guest_abi);
    CHECK_THAT(output,
               matches(classTemplateSpecializationDecl(hasName("guest_layout"), hasAnyTemplateArgument(refersToType(asString("struct A"))),
                                                       has(fieldDecl(hasName("data"), hasType(hasCanonicalType(asString("struct A"))))))));
    CHECK_THAT(output, guest_converter_defined);

    CHECK_THAT(output, host_layout_is_trivial);
  }

  // For repackable types, guest_layout explicitly lists its members
  SECTION("Repackable type") {
    const char* struct_def = "#ifdef HOST\n"
                             "struct A { int a; int b; };\n"
                             "#else\n"
                             "struct A { int b; int a; };\n"
                             "#endif\n";
    const auto output = run_thunkgen_host(struct_def, code, guest_abi);
    CHECK_THAT(output, matches(classTemplateSpecializationDecl(
                         hasName("guest_layout"), hasAnyTemplateArgument(refersToType(asString("struct A"))),
                         // The member "data" exists and is defined to a struct...
                         has(fieldDecl(hasName("data"), hasType(hasCanonicalType(hasDeclaration(decl(
                                                          // ... the members of which also use guest_layout (with fixed-size integers)
                                                          has(fieldDecl(hasName("a"), hasType(asString("guest_layout<int32_t>")))),
                                                          has(fieldDecl(hasName("b"), hasType(asString("guest_layout<int32_t>")))))))))))));
    CHECK_THAT(output, guest_converter_defined);

    CHECK_THAT(output, host_layout_is_trivial);
  }

  // For incompatible types, use of guest_layout nor host_layout should be prohibited
  SECTION("Incompatible type, unannotated") {
    const char* struct_def = "#ifdef HOST\n"
                             "struct A { int a; int b; };\n"
                             "#else\n"
                             "struct A { int c; int d; };\n"
                             "#endif\n";
    const auto output = run_thunkgen_host(struct_def, code, guest_abi);
    CHECK_THAT(output, layout_undefined("guest_layout"));
    CHECK_THAT(output, guest_converter_undefined);
    CHECK_THAT(output, layout_undefined("host_layout"));
  }

  // Layout wrappers can be enabled even for incompatible types using the emit_layout_wrappers annotation
  SECTION("Incompatible type, annotated") {
    // A slightly different setup is used here in order to construct a type which...
    // - has incompatible data layout (for both 32-bit and 64-bit guests)
    // - has consistently named members in struct A (which is required to emit layout wrappers)
    const char* struct_def = "#ifdef HOST\n"
                             "struct B { int a; };\n"
                             "#else\n"
                             "struct B { int b; };\n"
                             "#endif\n"
                             "struct A { B* a; int b; };\n";
    const std::string code = "#include <thunks_common.h>\n"
                             "template<typename> struct fex_gen_type {};\n"
                             "template<> struct fex_gen_type<A> : fexgen::emit_layout_wrappers {};\n";
    const auto output = run_thunkgen_host(struct_def, code, guest_abi);
    CHECK_THAT(output, matches(classTemplateSpecializationDecl(
                         hasName("guest_layout"), hasAnyTemplateArgument(refersToType(recordType(hasDeclaration(recordDecl(hasName("A")))))),
                         // The member "data" exists and is defined to a struct...
                         has(fieldDecl(hasName("data"), hasType(hasCanonicalType(hasDeclaration(decl(
                                                          // ... the members of which also use guest_layout
                                                          has(fieldDecl(hasName("a"), hasType(asString("guest_layout<" CLANG_STRUCT_PREFIX "B "
                                                                                                       "*>")))),
                                                          has(fieldDecl(hasName("b"), hasType(asString("guest_layout<int32_t>")))))))))))));
    CHECK_THAT(output, guest_converter_defined);

    CHECK_THAT(output, host_layout_is_trivial);
  }
}

// Some integer types are differently sized on the guest than on the host.
// All integer types are mapped to fixed-size equivalents when mentioned in a
// guest context hence. This test ensures the mapping is done correctly and
// the resulting guest_layout instantiations are convertible to host_layout.
TEST_CASE_METHOD(Fixture, "Mapping guest integers to fixed-size") {
  auto guest_abi = GENERATE(GuestABI::X86_32, GuestABI::X86_64);
  INFO(guest_abi);

  // Run each test a second time to ensure fixed-size integer mapping is
  // applied to pointees as well
  const std::string ptr = GENERATE("", " *");

  // Run each test with and without the ptr_passthrough annotation
  const bool passthrough_guest_type = GENERATE(false, true);

  // These types are differently sized on 32-bit guests
  SECTION("(u)intptr_t / size_t / long") {
    const std::string type = GENERATE("long", "unsigned long", "uintptr_t", "intptr_t", "size_t");
    INFO(type + ptr);
    const auto code = "#include <thunks_common.h>\n"
                      "#include <cstddef>\n"
                      "#include <cstdint>\n"
                      "void func(" +
                      type + ptr +
                      ");\n"
                      "template<> struct fex_gen_config<func> : fexgen::custom_host_impl {};\n" +
                      (passthrough_guest_type ? "template<> struct fex_gen_param<func, 0> : fexgen::ptr_passthrough {};\n" : "");
    if (!ptr.empty() && guest_abi == GuestABI::X86_32 && !passthrough_guest_type) {
      // Guest points to a 32-bit integer, but the host to a 64-bit one.
      // This should be detected as a failure.
      CHECK_THROWS_WITH(run_thunkgen_host("", code, guest_abi, true),
                        Catch::Matchers::ContainsSubstring("initialization of 'host_layout", Catch::CaseSensitive::No));
    } else {
      const auto output = run_thunkgen_host("", code, guest_abi);
      std::string expected_type = "guest_layout<";
      if (type == "size_t" || type.starts_with("u")) {
        expected_type += "u";
      }
      expected_type += (guest_abi == GuestABI::X86_32 ? +"int32_t" : "int64_t");
      expected_type += ptr + ">";
      CHECK_THAT(output, matches(functionDecl(hasName("fexfn_unpack_libtest_func"),
                                              // Packed argument struct should contain all parameters
                                              parameterCountIs(1),
                                              hasParameter(0, hasType(pointerType(pointee(hasUnqualifiedDesugaredType(recordType(
                                                                hasDeclaration(decl(has(fieldDecl(hasType(asString(expected_type)))))))))))))));

      // For passthrough parameters, the target function signature should
      // match the guest_layout type
      if (passthrough_guest_type) {
        CHECK_THAT(output, matches(functionDecl(hasName("fexfn_impl_libtest_func"), parameterCountIs(1),
                                                hasParameter(0, hasType(asString(expected_type))))));
      }
    }
  }

  // Most integer types are uniquely defined by specifying their size and
  // their signedness. (w)char-types and long-types are special:
  // * "char", "signed char", and "unsigned char" are different types
  // * "wchar_t" is mapped to "guest_layout<uint32_t>", but uint32_t
  //   itself is a type alias for "int"
  // * "long long" is mapped to "guest_layout<uint64_t>", but uint64_t
  //   itself is a type alias for "long" on 64-bit (which is a different
  //   type than "long long")
  //
  // This test section ensures that the correct fixed-size integers are used
  // *and* that they can be converted to host_layout.
  SECTION("Special integer types") {
    const std::string type = GENERATE("long long", "unsigned long long", "char", "unsigned char", "signed char", "wchar_t");
    std::string fixed_size_type = ((type.starts_with("unsigned") || type == "char" || type == "wchar_t") ? "u" : "");
    if (type.ends_with("long long")) {
      fixed_size_type += "int64_t";
    } else if (type.ends_with("wchar_t")) {
      fixed_size_type += "int32_t";
    } else {
      fixed_size_type += "int8_t";
    }
    INFO(type + ptr + ", expecting " + fixed_size_type + ptr);
    const auto code = "#include <thunks_common.h>\n"
                      "#include <cstdint>\n"
                      "void func(" +
                      type + ptr +
                      ");\n"
                      "template<> struct fex_gen_config<func> : fexgen::custom_host_impl {};\n" +
                      (passthrough_guest_type ? "template<> struct fex_gen_param<func, 0> : fexgen::ptr_passthrough {};\n" : "");
    const auto output = run_thunkgen_host("", code, guest_abi);
    CHECK_THAT(output, matches(functionDecl(
                         hasName("fexfn_unpack_libtest_func"),
                         // Packed argument struct should contain all parameters
                         parameterCountIs(1),
                         hasParameter(0, hasType(pointerType(pointee(hasUnqualifiedDesugaredType(recordType(hasDeclaration(
                                           decl(has(fieldDecl(hasType(asString("guest_layout<" + fixed_size_type + ptr + ">")))))))))))))));

    // For passthrough parameters, the target function signature should
    // match the guest_layout type
    if (passthrough_guest_type) {
      CHECK_THAT(output, matches(functionDecl(hasName("fexfn_impl_libtest_func"), parameterCountIs(1),
                                              hasParameter(0, hasType(asString("guest_layout<" + fixed_size_type + ptr + ">"))))));
    }
  }
}

TEST_CASE_METHOD(Fixture, "StructRepacking") {
  auto guest_abi = GENERATE(GuestABI::X86_32, GuestABI::X86_64);
  INFO(guest_abi);

  // All tests use the same function, but the prelude defining its parameter type "A" varies
  const std::string code = "#include <thunks_common.h>\n"
                           "void func(A*);\n"
                           "template<auto> struct fex_gen_config {};\n"
                           "template<> struct fex_gen_config<func> : fexgen::custom_host_impl {};\n";

  SECTION("Pointer to struct with consistent data layout") {
    CHECK_NOTHROW(run_thunkgen_host("struct A { int a; };\n", code, guest_abi));
  }

  SECTION("Pointer to struct with unannotated pointer member with inconsistent data layout") {
    const auto prelude = "#ifdef HOST\n"
                         "struct B { int a; };\n"
                         "#else\n"
                         "struct B { int b; };\n"
                         "#endif\n"
                         "struct A { B* a; };\n";

    SECTION("Parameter unannotated") {
      CHECK_THROWS(run_thunkgen_host(prelude, code, guest_abi, true));
    }

    SECTION("Parameter annotated as ptr_passthrough") {
      CHECK_NOTHROW(run_thunkgen_host(prelude, code + "template<> struct fex_gen_param<func, 0, A*> : fexgen::ptr_passthrough {};\n", guest_abi));
    }

    SECTION("Struct member annotated as custom_repack") {
      CHECK_NOTHROW(run_thunkgen_host("struct A { void* a; };\n",
                                      code + "template<> struct fex_gen_config<&A::a> : fexgen::custom_repack {};\n", guest_abi));
    }
  }

  SECTION("Pointer to struct with pointer member of consistent data layout") {
    std::string type = GENERATE("char", "short", "int", "float");
    REQUIRE_NOTHROW(run_thunkgen_host("struct A { " + type + "* a; };\n", code, guest_abi));
  }

  SECTION("Pointer to struct with pointer member of opaque type") {
    const auto prelude = "struct B;\n"
                         "struct A { B* a; };\n";

    // Unannotated
    REQUIRE_THROWS_WITH(run_thunkgen_host(prelude, code, guest_abi), Catch::Matchers::ContainsSubstring("incomplete type"));

    // Annotated as opaque_type
    CHECK_NOTHROW(run_thunkgen_host(prelude, code + "template<> struct fex_gen_type<B> : fexgen::opaque_type {};\n", guest_abi));
  }
}

TEST_CASE_METHOD(Fixture, "VoidPointerParameter") {
  auto guest_abi = GENERATE(GuestABI::X86_32, GuestABI::X86_64);
  INFO(guest_abi);

  SECTION("Unannotated") {
    const char* code = "#include <thunks_common.h>\n"
                       "void func(void*);\n"
                       "template<> struct fex_gen_config<func> {};\n";
    if (guest_abi == GuestABI::X86_32) {
      // TODO: Currently not considered an error
      //            CHECK_THROWS_WITH(run_thunkgen_host("", code, guest_abi, true), Catch::Matchers::ContainsSubstring("unsupported parameter type", Catch::CaseSensitive::No));
    } else {
      // Pointee data is assumed to be compatible on 64-bit
      CHECK_NOTHROW(run_thunkgen_host("", code, guest_abi));
    }
  }

  SECTION("Passthrough") {
    const char* code = "#include <thunks_common.h>\n"
                       "void func(void*);\n"
                       "template<> struct fex_gen_config<func> : fexgen::custom_host_impl {};\n"
                       "template<> struct fex_gen_param<func, 0, void*> : fexgen::ptr_passthrough {};\n";
    CHECK_NOTHROW(run_thunkgen_host("", code, guest_abi));
  }

  SECTION("Assumed compatible") {
    const char* code = "#include <thunks_common.h>\n"
                       "void func(void*);\n"
                       "template<> struct fex_gen_config<func> {};\n"
                       "template<> struct fex_gen_param<func, 0, void*> : fexgen::assume_compatible_data_layout {};\n";
    CHECK_NOTHROW(run_thunkgen_host("", code, guest_abi));
  }

  SECTION("Unannotated in struct") {
    const char* prelude = "struct A { void* a; };\n";
    const char* code = "#include <thunks_common.h>\n"
                       "void func(A*);\n"
                       "template<> struct fex_gen_config<func> {};\n";
    if (guest_abi == GuestABI::X86_32) {
      CHECK_THROWS_WITH(run_thunkgen_host(prelude, code, guest_abi, true),
                        Catch::Matchers::ContainsSubstring("unsupported parameter type", Catch::CaseSensitive::No));
    } else {
      CHECK_NOTHROW(run_thunkgen_host(prelude, code, guest_abi));
    }
  }

  SECTION("Custom repack in struct") {
    const char* prelude = "struct A { void* a; };\n";
    const char* code = "#include <thunks_common.h>\n"
                       "void func(A*);\n"
                       "template<> struct fex_gen_config<&A::a> : fexgen::custom_repack {};\n"
                       "template<> struct fex_gen_config<func> {};\n";
    CHECK_NOTHROW(run_thunkgen_host(prelude, code, guest_abi));
  }
}