//===--- CodeCompletionResultBuilder.cpp ----------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2018 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//

#include "CodeCompletionResultBuilder.h"
#include "CodeCompletionDiagnostics.h"
#include "swift/AST/ASTContext.h"
#include "swift/AST/ASTDemangler.h"
#include "swift/AST/USRGeneration.h"
#include "swift/Basic/Assertions.h"
#include "swift/Basic/LLVM.h"
#include "swift/IDE/CodeCompletionStringPrinter.h"
#include "swift/IDE/CommentConversion.h"
#include "swift/IDE/Utils.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Comment.h"
#include "clang/Basic/Module.h"
#include "clang/Index/USRGeneration.h"

using namespace swift;
using namespace swift::ide;

static bool shouldCopyAssociatedUSRForDecl(const ValueDecl *VD) {
  // Avoid trying to generate a USR for some declaration types.
  if (isa<GenericTypeParamDecl>(VD))
    return false;
  if (isa<ParamDecl>(VD))
    return false;
  if (isa<ModuleDecl>(VD))
    return false;
  if (VD->hasClangNode() && !VD->getClangDecl())
    return false;

  // Avoid generating USRs for decls in local contexts, we cannot guarantee
  // any parent closures will be type-checked, which is needed for mangling.
  if (VD->getDeclContext()->getLocalContext())
    return false;

  return true;
}

template <typename FnTy>
static void walkValueDeclAndOverriddenDecls(const Decl *D, const FnTy &Fn) {
  if (auto *VD = dyn_cast<ValueDecl>(D)) {
    Fn(VD);
    walkOverriddenDecls(VD, Fn);
  }
}

static ArrayRef<NullTerminatedStringRef>
copyAssociatedUSRs(llvm::BumpPtrAllocator &Allocator, const Decl *D) {
  llvm::SmallVector<NullTerminatedStringRef, 4> USRs;
  walkValueDeclAndOverriddenDecls(
      D,
      [&](llvm::PointerUnion<const ValueDecl *, const clang::NamedDecl *> OD) {
        llvm::SmallString<128> SS;
        bool Ignored = true;
        if (auto *OVD = OD.dyn_cast<const ValueDecl *>()) {
          if (shouldCopyAssociatedUSRForDecl(OVD)) {
            llvm::raw_svector_ostream OS(SS);
            Ignored = printValueDeclUSR(OVD, OS);
          }
        } else if (auto *OND = OD.dyn_cast<const clang::NamedDecl *>()) {
          Ignored = clang::index::generateUSRForDecl(OND, SS);
        }

        if (!Ignored)
          USRs.emplace_back(SS, Allocator);
      });

  if (!USRs.empty())
    return llvm::ArrayRef(USRs).copy(Allocator);

  return {};
}

static NullTerminatedStringRef copySwiftUSR(llvm::BumpPtrAllocator &Allocator,
                                            const Decl *D) {
  auto *VD = dyn_cast<ValueDecl>(D);
  if (!VD || !shouldCopyAssociatedUSRForDecl(VD))
    return NullTerminatedStringRef();

  SmallString<128> SS;
  llvm::raw_svector_ostream OS(SS);
  if (!ide::printValueDeclSwiftUSR(VD, OS))
    return NullTerminatedStringRef(SS, Allocator);

  return NullTerminatedStringRef();
}

/// Tries to reconstruct the provided \p D declaration using \c
/// Demangle::getDeclForUSR and verifies that the declarations match. This only
/// works if \p D is a \c ValueDecl and \c shouldCopyAssociatedUSRForDecl is
/// true.
///
/// This is intended for testing only.
static void verifyUSRToDeclReconstruction(const Decl *D) {
  auto *VD = dyn_cast<ValueDecl>(D);
  if (!VD)
    return;

  if (!shouldCopyAssociatedUSRForDecl(VD))
    return;

  SmallString<128> SwiftUSR;

  llvm::raw_svector_ostream OS(SwiftUSR);
  if (ide::printValueDeclSwiftUSR(VD, OS)) {
    ABORT([&](auto &out) {
      out << "Declaration should have a Swift USR:\n";
      VD->dump(out);
    });
  }

  auto &Ctx = VD->getASTContext();
  auto *Reconstructed = Demangle::getDeclForUSR(Ctx, SwiftUSR);

  if (!Reconstructed) {
    ABORT([&](auto &out) {
      out << "Reconstructed declaration shouldn't be null\n"
          << "Swift USR: " << SwiftUSR << ", original declaration:\n";
      VD->dump(out);
    });
  }

  if (Reconstructed != VD) {
    ABORT([&](auto &out) {
      out << "Reconstructed declaration should match the original one\n"
          << "Swift USR: " << SwiftUSR << "\n"
          << "Original declaration:\n";
      VD->dump(out);
      out << "Reconstructed declaration:\n";
      Reconstructed->dump(out);
    });
  }
}

CodeCompletionResult *CodeCompletionResultBuilder::takeResult() {
  auto &Allocator = *Sink.Allocator;
  auto *CCS = createCompletionString();

  if (Sink.verifyUSRToDecl && AssociatedDecl) {
    verifyUSRToDeclReconstruction(AssociatedDecl);
  }

  CodeCompletionDiagnosticSeverity ContextFreeDiagnosticSeverity =
      CodeCompletionDiagnosticSeverity::None;
  NullTerminatedStringRef ContextFreeDiagnosticMessage;
  if (ContextFreeNotRecReason != ContextFreeNotRecommendedReason::None) {
    assert(AssociatedDecl != nullptr &&
           "There should be no case where ContextFreeNotRecReason != None && "
           "AssociatedDecl == nulptr");
    // FIXME: We should generate the message lazily.
    if (const auto *VD = dyn_cast_or_null<ValueDecl>(AssociatedDecl)) {
      CodeCompletionDiagnosticSeverity severity;
      SmallString<256> message;
      llvm::raw_svector_ostream messageOS(message);
      if (!getContextFreeCompletionDiagnostics(ContextFreeNotRecReason, VD,
                                               severity, messageOS)) {
        ContextFreeDiagnosticSeverity = severity;
        ContextFreeDiagnosticMessage =
            NullTerminatedStringRef(message, Allocator);
      }
    }
  }

  /// This variable should be initialized by all the switch cases below.
  ContextFreeCodeCompletionResult *ContextFreeResult = nullptr;

  switch (Kind) {
  case CodeCompletionResultKind::Declaration: {
    NullTerminatedStringRef ModuleName;
    if (CurrentModule) {
      if (Sink.LastModule.first == CurrentModule.getOpaqueValue()) {
        ModuleName = Sink.LastModule.second;
      } else {
        if (auto *C = CurrentModule.dyn_cast<const clang::Module *>()) {
          ModuleName =
              NullTerminatedStringRef(C->getFullModuleName(), Allocator);
        } else {
          ModuleName = NullTerminatedStringRef(
              cast<const swift::ModuleDecl *>(CurrentModule)->getName().str(),
              Allocator);
        }
        Sink.LastModule.first = CurrentModule.getOpaqueValue();
        Sink.LastModule.second = ModuleName;
      }
    }

    ContextFreeResult = ContextFreeCodeCompletionResult::createDeclResult(
        Sink, CCS, AssociatedDecl, HasAsyncAlternative, ModuleName,
        NullTerminatedStringRef(BriefDocComment, Allocator),
        copyAssociatedUSRs(Allocator, AssociatedDecl),
        copySwiftUSR(Allocator, AssociatedDecl), ResultType,
        ContextFreeNotRecReason, ContextFreeDiagnosticSeverity,
        ContextFreeDiagnosticMessage);
    break;
  }

  case CodeCompletionResultKind::Keyword:
    ContextFreeResult = ContextFreeCodeCompletionResult::createKeywordResult(
        Sink, KeywordKind, CCS,
        NullTerminatedStringRef(BriefDocComment, Allocator), ResultType);
    break;
  case CodeCompletionResultKind::BuiltinOperator:
  case CodeCompletionResultKind::Pattern:
    ContextFreeResult =
        ContextFreeCodeCompletionResult::createPatternOrBuiltInOperatorResult(
            Sink, Kind, CCS, CodeCompletionOperatorKind::None,
            NullTerminatedStringRef(BriefDocComment, Allocator), ResultType,
            ContextFreeNotRecReason, ContextFreeDiagnosticSeverity,
            ContextFreeDiagnosticMessage);
    break;
  case CodeCompletionResultKind::Literal:
    assert(LiteralKind.has_value());
    ContextFreeResult = ContextFreeCodeCompletionResult::createLiteralResult(
        Sink, *LiteralKind, CCS, ResultType);
    break;
  }

  if (Sink.shouldProduceContextFreeResults()) {
    // If the sink only intends to store the context free results in the cache,
    // we don't need to compute any contextual properties.
    return new (Allocator) CodeCompletionResult(
        *ContextFreeResult, AssociatedDecl, SemanticContextKind::None,
        CodeCompletionFlair(), /*NumBytesToErase=*/0,
        CodeCompletionResultTypeRelation::Unrelated,
        ContextualNotRecommendedReason::None);
  } else {
    assert(
        ContextFreeResult != nullptr &&
        "ContextFreeResult should have been constructed by the switch above");

    // We know that the ContextFreeResult has an AST-based type because it was
    // just computed and not read from the cache and
    // Sink.shouldProduceContextFreeResults() is false. So we can pass nullptr
    // for USRTypeContext.
    CodeCompletionResultTypeRelation typeRelation =
        ContextFreeResult->calculateContextualTypeRelation(
            DC, TypeContext, /*usrTypeContext=*/nullptr);
    ContextualNotRecommendedReason notRecommendedReason =
        ContextFreeResult->calculateContextualNotRecommendedReason(
            ContextualNotRecReason, CanCurrDeclContextHandleAsync);

    return new (Allocator) CodeCompletionResult(
        *ContextFreeResult, AssociatedDecl, SemanticContext, Flair,
        NumBytesToErase, typeRelation, notRecommendedReason);
  }
}

void CodeCompletionResultBuilder::finishResult() {
  if (!Cancelled)
    Sink.Results.push_back(takeResult());
}

void CodeCompletionResultBuilder::setAssociatedDecl(const Decl *D) {
  assert(Kind == CodeCompletionResultKind::Declaration);

  AssociatedDecl = D;

  if (auto *ClangD = D->getClangDecl())
    CurrentModule = ClangD->getImportedOwningModule();
  // FIXME: macros
  // FIXME: imported header module

  if (!CurrentModule) {
    ModuleDecl *MD = D->getModuleContext();

    // If this is an underscored cross-import overlay, map it to the underlying
    // module that declares it instead.
    if (ModuleDecl *Declaring = MD->getDeclaringModuleIfCrossImportOverlay())
      MD = Declaring;

    CurrentModule = MD;
  }

  if (D->isDeprecated())
    setContextFreeNotRecommended(ContextFreeNotRecommendedReason::Deprecated);
  else if (D->getSoftDeprecatedAttr())
    setContextFreeNotRecommended(
        ContextFreeNotRecommendedReason::SoftDeprecated);

  if (D->getClangNode()) {
    if (auto *ClangD = D->getClangDecl()) {
      const auto &ClangContext = ClangD->getASTContext();
      if (const clang::RawComment *RC =
              ClangContext.getRawCommentForAnyRedecl(ClangD)) {
        setBriefDocComment(RC->getBriefText(ClangContext));
      }
    }
  } else {
    setBriefDocComment(AssociatedDecl->getSemanticBriefComment());
  }
}