//===--- DarwinSDKInfo.cpp - SDK Information parser for darwin - ----------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#include "clang/Basic/DarwinSDKInfo.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/Support/ErrorOr.h"
#include "llvm/Support/JSON.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Path.h"
#include <optional>

using namespace clang;

std::optional<VersionTuple> DarwinSDKInfo::RelatedTargetVersionMapping::map(
    const VersionTuple &Key, const VersionTuple &MinimumValue,
    std::optional<VersionTuple> MaximumValue) const {
  if (Key < MinimumKeyVersion)
    return MinimumValue;
  if (Key > MaximumKeyVersion)
    return MaximumValue;
  auto KV = Mapping.find(Key.normalize());
  if (KV != Mapping.end())
    return KV->getSecond();
  // If no exact entry found, try just the major key version. Only do so when
  // a minor version number is present, to avoid recursing indefinitely into
  // the major-only check.
  if (Key.getMinor())
    return map(VersionTuple(Key.getMajor()), MinimumValue, MaximumValue);
  // If this a major only key, return std::nullopt for a missing entry.
  return std::nullopt;
}

std::optional<DarwinSDKInfo::RelatedTargetVersionMapping>
DarwinSDKInfo::RelatedTargetVersionMapping::parseJSON(
    const llvm::json::Object &Obj, VersionTuple MaximumDeploymentTarget) {
  VersionTuple Min = VersionTuple(std::numeric_limits<unsigned>::max());
  VersionTuple Max = VersionTuple(0);
  VersionTuple MinValue = Min;
  llvm::DenseMap<VersionTuple, VersionTuple> Mapping;
  for (const auto &KV : Obj) {
    if (auto Val = KV.getSecond().getAsString()) {
      llvm::VersionTuple KeyVersion;
      llvm::VersionTuple ValueVersion;
      if (KeyVersion.tryParse(KV.getFirst()) || ValueVersion.tryParse(*Val))
        return std::nullopt;
      Mapping[KeyVersion.normalize()] = ValueVersion;
      if (KeyVersion < Min)
        Min = KeyVersion;
      if (KeyVersion > Max)
        Max = KeyVersion;
      if (ValueVersion < MinValue)
        MinValue = ValueVersion;
    }
  }
  if (Mapping.empty())
    return std::nullopt;
  return RelatedTargetVersionMapping(
      Min, Max, MinValue, MaximumDeploymentTarget, std::move(Mapping));
}

static std::optional<StringRef>
parseXcodePlatform(const llvm::json::Object &Obj) {
  // The CanonicalName is the Xcode platform followed by a version, e.g.
  // macosx15.0.
  auto CanonicalName = Obj.getString("CanonicalName");
  if (!CanonicalName)
    return std::nullopt;
  size_t VersionStart = CanonicalName->find_first_of("0123456789");
  return CanonicalName->slice(0, VersionStart);
}

static std::pair<llvm::Triple::OSType, llvm::Triple::EnvironmentType>
parseOSAndEnvironment(std::optional<StringRef> XcodePlatform) {
  if (!XcodePlatform)
    return {llvm::Triple::UnknownOS, llvm::Triple::UnknownEnvironment};

  llvm::Triple::OSType OS =
      llvm::StringSwitch<llvm::Triple::OSType>(*XcodePlatform)
          .Case("macosx", llvm::Triple::MacOSX)
          .Cases({"iphoneos", "iphonesimulator"}, llvm::Triple::IOS)
          .Cases({"appletvos", "appletvsimulator"}, llvm::Triple::TvOS)
          .Cases({"watchos", "watchsimulator"}, llvm::Triple::WatchOS)
          .Case("bridgeos", llvm::Triple::BridgeOS)
          .Cases({"xros", "xrsimulator"}, llvm::Triple::XROS)
          .Case("driverkit", llvm::Triple::DriverKit)
          .Default(llvm::Triple::UnknownOS);

  llvm::Triple::EnvironmentType Environment =
      llvm::StringSwitch<llvm::Triple::EnvironmentType>(*XcodePlatform)
          .Cases({"iphonesimulator", "appletvsimulator", "watchsimulator",
                  "xrsimulator"},
                 llvm::Triple::Simulator)
          .Default(llvm::Triple::UnknownEnvironment);

  return {OS, Environment};
}

static DarwinSDKInfo::PlatformInfoStorageType parsePlatformInfos(
    const llvm::json::Object &Obj, std::optional<StringRef> XcodePlatform,
    llvm::Triple::OSType SDKOS, llvm::Triple::EnvironmentType SDKEnvironment,
    VersionTuple Version) {
  DarwinSDKInfo::PlatformInfoStorageType PlatformInfos;
  auto SupportedTargets = Obj.getObject("SupportedTargets");
  if (!SupportedTargets) {
    // For older SDKs that don't have SupportedTargets, infer one from the SDK's
    // OS/Environment.
    StringRef PlatformPrefix;
    if (SDKOS == llvm::Triple::DriverKit)
      PlatformPrefix = "/System/DriverKit";
    PlatformInfos.push_back({llvm::Triple::Apple, SDKOS, SDKEnvironment,
                             llvm::Triple::MachO, PlatformPrefix});
    return PlatformInfos;
  }

  for (auto SupportedTargetPair : *SupportedTargets) {
    llvm::json::Object *SupportedTarget =
        SupportedTargetPair.getSecond().getAsObject();
    auto Vendor = SupportedTarget->getString("LLVMTargetTripleVendor");
    auto OS = SupportedTarget->getString("LLVMTargetTripleSys");
    if (!Vendor || !OS)
      continue;

    StringRef Arch = llvm::Triple::getArchName(llvm::Triple::UnknownArch);
    auto Environment =
        SupportedTarget->getString("LLVMTargetTripleEnvironment");
    llvm::Triple Triple;
    if (Environment)
      Triple = llvm::Triple(Arch, *Vendor, *OS, *Environment);
    else
      Triple = llvm::Triple(Arch, *Vendor, *OS);

    // The key is either the Xcode platform, or a variant. The platform must be
    // the first entry in the returned PlatformInfoStorageType.
    StringRef PlatformOrVariant = SupportedTargetPair.getFirst();

    StringRef EffectivePlatformPrefix;
    // Ignore iosmac value if it exists.
    if ((PlatformOrVariant != "iosmac") || (Version >= VersionTuple(99))) {
      auto PlatformPrefix = SupportedTarget->getString("SystemPrefix");
      if (PlatformPrefix) {
        EffectivePlatformPrefix = *PlatformPrefix;
      } else {
        // Older SDKs don't have SystemPrefix in SupportedTargets, manually add
        // their prefixes.
        if ((Triple.getOS() == llvm::Triple::DriverKit) &&
            (Version < VersionTuple(22, 1)))
          EffectivePlatformPrefix = "/System/DriverKit";
      }
    }

    DarwinSDKInfo::SDKPlatformInfo PlatformInfo(
        Triple.getVendor(), Triple.getOS(), Triple.getEnvironment(),
        Triple.getObjectFormat(), EffectivePlatformPrefix);
    if (PlatformOrVariant == XcodePlatform)
      PlatformInfos.insert(PlatformInfos.begin(), PlatformInfo);
    else
      PlatformInfos.push_back(PlatformInfo);
  }
  return PlatformInfos;
}

static std::optional<VersionTuple> getVersionKey(const llvm::json::Object &Obj,
                                                 StringRef Key) {
  auto Value = Obj.getString(Key);
  if (!Value)
    return std::nullopt;
  VersionTuple Version;
  if (Version.tryParse(*Value))
    return std::nullopt;
  return Version;
}

std::optional<DarwinSDKInfo>
DarwinSDKInfo::parseDarwinSDKSettingsJSON(std::string FilePath,
                                          const llvm::json::Object *Obj) {
  auto Version = getVersionKey(*Obj, "Version");
  if (!Version)
    return std::nullopt;
  auto MaximumDeploymentVersion =
      getVersionKey(*Obj, "MaximumDeploymentTarget");
  if (!MaximumDeploymentVersion)
    return std::nullopt;
  std::optional<StringRef> XcodePlatform = parseXcodePlatform(*Obj);
  std::pair<llvm::Triple::OSType, llvm::Triple::EnvironmentType>
      OSAndEnvironment = parseOSAndEnvironment(XcodePlatform);
  // DisplayName should always be present, but don't require it.
  StringRef DisplayName =
      Obj->getString("DisplayName")
          .value_or(Obj->getString("CanonicalName").value_or("<unknown>"));
  PlatformInfoStorageType PlatformInfos =
      parsePlatformInfos(*Obj, XcodePlatform, OSAndEnvironment.first,
                         OSAndEnvironment.second, *Version);
  llvm::DenseMap<OSEnvPair::StorageType,
                 std::optional<RelatedTargetVersionMapping>>
      VersionMappings;
  if (const auto *VM = Obj->getObject("VersionMap")) {
    // FIXME: Generalize this out beyond iOS-deriving targets.
    // Look for ios_<targetos> version mapping for targets that derive from ios.
    for (const auto &KV : *VM) {
      auto Pair = StringRef(KV.getFirst()).split("_");
      if (Pair.first.compare_insensitive("ios") == 0) {
        llvm::Triple TT(llvm::Twine("--") + Pair.second.lower());
        if (TT.getOS() != llvm::Triple::UnknownOS) {
          auto Mapping = RelatedTargetVersionMapping::parseJSON(
              *KV.getSecond().getAsObject(), *MaximumDeploymentVersion);
          if (Mapping)
            VersionMappings[OSEnvPair(llvm::Triple::IOS,
                                      llvm::Triple::UnknownEnvironment,
                                      TT.getOS(),
                                      llvm::Triple::UnknownEnvironment)
                                .Value] = std::move(Mapping);
        }
      }
    }

    if (const auto *Mapping = VM->getObject("macOS_iOSMac")) {
      auto VersionMap = RelatedTargetVersionMapping::parseJSON(
          *Mapping, *MaximumDeploymentVersion);
      if (!VersionMap)
        return std::nullopt;
      VersionMappings[OSEnvPair::macOStoMacCatalystPair().Value] =
          std::move(VersionMap);
    }
    if (const auto *Mapping = VM->getObject("iOSMac_macOS")) {
      auto VersionMap = RelatedTargetVersionMapping::parseJSON(
          *Mapping, *MaximumDeploymentVersion);
      if (!VersionMap)
        return std::nullopt;
      VersionMappings[OSEnvPair::macCatalystToMacOSPair().Value] =
          std::move(VersionMap);
    }
  }

  return DarwinSDKInfo(std::move(FilePath), OSAndEnvironment.first,
                       OSAndEnvironment.second, std::move(*Version),
                       DisplayName, std::move(*MaximumDeploymentVersion),
                       std::move(PlatformInfos), std::move(VersionMappings));
}

Expected<std::optional<DarwinSDKInfo>>
clang::parseDarwinSDKInfo(llvm::vfs::FileSystem &VFS, StringRef SDKRootPath) {
  llvm::SmallString<256> Filepath = SDKRootPath;
  llvm::sys::path::append(Filepath, "SDKSettings.json");
  llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> File =
      VFS.getBufferForFile(Filepath);
  if (!File) {
    // If the file couldn't be read, assume it just doesn't exist.
    return std::nullopt;
  }
  Expected<llvm::json::Value> Result =
      llvm::json::parse(File.get()->getBuffer());
  if (!Result)
    return Result.takeError();

  if (const auto *Obj = Result->getAsObject()) {
    if (auto SDKInfo = DarwinSDKInfo::parseDarwinSDKSettingsJSON(
            Filepath.str().str(), Obj))
      return std::move(SDKInfo);
  }
  return llvm::make_error<llvm::StringError>("invalid SDKSettings.json",
                                             llvm::inconvertibleErrorCode());
}