//===--- libSwiftSyntaxParser.cpp - C API for Swift Syntax Parsing --------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2019 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
//
//===----------------------------------------------------------------------===//
//
// This C API is primarily intended to serve as the Swift parsing component
// of SwiftSyntax (https://github.com/apple/swift-syntax).
//
//===----------------------------------------------------------------------===//

#include "swift-c/SyntaxParser/SwiftSyntaxParser.h"
#include "swift/AST/Module.h"
#include "swift/Basic/LangOptions.h"
#include "swift/Basic/SourceManager.h"
#include "swift/Parse/Parser.h"
#include "swift/Parse/SyntaxParseActions.h"
#include "swift/Syntax/Serialization/SyntaxSerialization.h"
#include "swift/Syntax/SyntaxNodes.h"
#include "swift/Subsystems.h"
#include <Block.h>

using namespace swift;
using namespace swift::syntax;

typedef swiftparse_range_t CRange;
typedef swiftparse_client_node_t CClientNode;
typedef swiftparse_syntax_node_t CRawSyntaxNode;
typedef swiftparse_trivia_piece_t CTriviaPiece;
typedef swiftparse_syntax_kind_t CSyntaxKind;

namespace {

static unsigned getByteOffset(SourceLoc Loc, SourceManager &SM,
                              unsigned BufferID) {
  return Loc.isValid() ? SM.getLocOffsetInBuffer(Loc, BufferID) : 0;
}

static void initCRange(CRange &c_range, CharSourceRange range, SourceManager &SM,
                       unsigned BufferID) {
  if (range.isValid()) {
    c_range.offset = getByteOffset(range.getStart(), SM, BufferID);
    c_range.length = range.getByteLength();
  } else {
    c_range.offset = 0;
    c_range.length = 0;
  }
}

class SynParser {
  swiftparse_node_handler_t NodeHandler = nullptr;
  swiftparse_node_lookup_t NodeLookup = nullptr;
  swiftparse_diagnostic_handler_t DiagHandler = nullptr;

public:
  swiftparse_node_handler_t getNodeHandler() const {
    return NodeHandler;
  }

  swiftparse_node_lookup_t getNodeLookup() const {
    return NodeLookup;
  }

  swiftparse_diagnostic_handler_t getDiagnosticHandler() const {
    return DiagHandler;
  }

  void setNodeHandler(swiftparse_node_handler_t hdl) {
    auto prevBlk = NodeHandler;
    NodeHandler = Block_copy(hdl);
    Block_release(prevBlk);
  }

  void setNodeLookup(swiftparse_node_lookup_t lookupBlk) {
    auto prevBlk = NodeLookup;
    NodeLookup = Block_copy(lookupBlk);
    Block_release(prevBlk);
  }

  void setDiagnosticHandler(swiftparse_diagnostic_handler_t hdl) {
    auto prevBlk = DiagHandler;
    DiagHandler = Block_copy(hdl);
    Block_release(prevBlk);
  }

  ~SynParser() {
    setNodeHandler(nullptr);
    setNodeLookup(nullptr);
    setDiagnosticHandler(nullptr);
  }

  swiftparse_client_node_t parse(const char *source, size_t len);
};

struct DeferredTokenNode {
  bool IsMissing;
  tok TokenKind;
  StringRef LeadingTrivia;
  StringRef TrailingTrivia;
  /// The range of the token including trivia.
  CharSourceRange Range;

  DeferredTokenNode(bool IsMissing, tok TokenKind, StringRef LeadingTrivia,
                    StringRef TrailingTrivia, CharSourceRange Range)
      : IsMissing(IsMissing), TokenKind(TokenKind),
        LeadingTrivia(LeadingTrivia), TrailingTrivia(TrailingTrivia),
        Range(Range) {}

  /// Returns the length of this token or \c 0 if the token is missing.
  size_t getLength() const {
    if (IsMissing) {
      return 0;
    } else {
      assert(Range.isValid());
      return Range.getByteLength();
    }
  }
};

struct DeferredLayoutNode {
  syntax::SyntaxKind Kind;
  ArrayRef<RecordedOrDeferredNode> Children;
  unsigned Length;

  DeferredLayoutNode(syntax::SyntaxKind Kind,
                     ArrayRef<RecordedOrDeferredNode> Children, unsigned Length)
      : Kind(Kind), Children(Children), Length(Length) {}
};

class CLibParseActions final : public SyntaxParseActions {
  SynParser &SynParse;
  SourceManager &SM;
  unsigned BufferID;
  llvm::BumpPtrAllocator DeferredNodeAllocator;

public:
  CLibParseActions(SynParser &synParse, SourceManager &sm, unsigned bufID)
  : SynParse(synParse), SM(sm), BufferID(bufID) {}

private:
  swiftparse_node_handler_t getNodeHandler() const {
    return SynParse.getNodeHandler();
  }

  swiftparse_node_lookup_t getNodeLookup() const {
    return SynParse.getNodeLookup();
  }

  static void makeCTrivia(SmallVectorImpl<CTriviaPiece> &c_trivia,
                          ArrayRef<ParsedTriviaPiece> trivia) {
    for (const auto &piece : trivia) {
      CTriviaPiece c_piece;
      auto numValue =
        serialization::getNumericValue(piece.getKind());
      c_piece.kind = numValue;
      assert(c_piece.kind == numValue && "trivia kind value is too large");
      c_piece.length = piece.getLength();
      c_trivia.push_back(c_piece);
    }
  }

  void makeCRange(CRange &c_range, CharSourceRange range) {
    return initCRange(c_range, range, SM, BufferID);
  }

  void makeCRawToken(CRawSyntaxNode &node,
                     tok kind,
                     ArrayRef<CTriviaPiece> leadingTrivia,
                     ArrayRef<CTriviaPiece> trailingTrivia,
                     CharSourceRange range) {
    node.kind = serialization::getNumericValue(SyntaxKind::Token);
    auto numValue = serialization::getNumericValue(kind);
    node.token_data.kind = numValue;
    assert(node.token_data.kind == numValue && "token kind value is too large");
    node.token_data.leading_trivia = leadingTrivia.data();
    node.token_data.leading_trivia_count = leadingTrivia.size();
    assert(node.token_data.leading_trivia_count == leadingTrivia.size() &&
           "leading trivia count value is too large");
    node.token_data.trailing_trivia = trailingTrivia.data();
    node.token_data.trailing_trivia_count = trailingTrivia.size();
    assert(node.token_data.trailing_trivia_count == trailingTrivia.size() &&
           "trailing trivia count value is too large");
    makeCRange(node.token_data.range, range);
    node.present = true;
  }

  OpaqueSyntaxNode recordToken(tok tokenKind, StringRef leadingTrivia,
                               StringRef trailingTrivia,
                               CharSourceRange range) override {
    auto leadingTriviaPieces = TriviaLexer::lexTrivia(leadingTrivia).Pieces;
    auto trailingTriviaPieces = TriviaLexer::lexTrivia(trailingTrivia).Pieces;

    SmallVector<CTriviaPiece, 8> c_leadingTrivia, c_trailingTrivia;
    makeCTrivia(c_leadingTrivia, leadingTriviaPieces);
    makeCTrivia(c_trailingTrivia, trailingTriviaPieces);
    CRawSyntaxNode node;
    makeCRawToken(node, tokenKind, c_leadingTrivia, c_trailingTrivia,
                  range);
    return getNodeHandler()(&node);
  }

  OpaqueSyntaxNode recordMissingToken(tok tokenKind, SourceLoc loc) override {
    CRawSyntaxNode node;
    makeCRawToken(node, tokenKind, {}, {}, CharSourceRange{loc, 0});
    node.present = false;
    return getNodeHandler()(&node);
  }

  OpaqueSyntaxNode
  recordRawSyntax(SyntaxKind kind,
                  ArrayRef<OpaqueSyntaxNode> elements) override {
    CRawSyntaxNode node;
    auto numValue = serialization::getNumericValue(kind);
    node.kind = numValue;
    assert(node.kind == numValue && "syntax kind value is too large");
    node.layout_data.nodes =
        const_cast<const swiftparse_client_node_t *>(elements.data());
    node.layout_data.nodes_count = elements.size();
    node.present = true;
    return getNodeHandler()(&node);
  }

  Optional<SourceFileSyntax> realizeSyntaxRoot(OpaqueSyntaxNode root,
                                               const SourceFile &SF) override {
    // We don't support realizing syntax nodes from the C layout.
    return None;
  }

  std::pair<size_t, OpaqueSyntaxNode>
  lookupNode(size_t lexerOffset, SyntaxKind kind) override {
    auto NodeLookup = getNodeLookup();
    if (!NodeLookup) {
      return {0, nullptr};
    }
    auto numValue = serialization::getNumericValue(kind);
    CSyntaxKind ckind = numValue;
    assert(ckind == numValue && "syntax kind value is too large");
    auto result = NodeLookup(lexerOffset, ckind);
    return {result.length, result.node};
  }

  OpaqueSyntaxNode makeDeferredToken(tok tokenKind, StringRef leadingTrivia,
                                     StringRef trailingTrivia,
                                     CharSourceRange range,
                                     bool isMissing) override {
    return new (DeferredNodeAllocator) DeferredTokenNode(
        isMissing, tokenKind, leadingTrivia, trailingTrivia, range);
  }

  OpaqueSyntaxNode makeDeferredLayout(
      syntax::SyntaxKind k, bool isMissing,
      const MutableArrayRef<ParsedRawSyntaxNode> &parsedChildren) override {
    assert(!isMissing && "Missing layout nodes not implemented yet");

    auto childrenMem = DeferredNodeAllocator.Allocate<RecordedOrDeferredNode>(
        parsedChildren.size());
    auto children =
        llvm::makeMutableArrayRef(childrenMem, parsedChildren.size());

    // Compute the length of this node.
    unsigned length = 0;
    size_t index = 0;
    for (auto &parsedChild : parsedChildren) {
      auto child = parsedChild.takeRecordedOrDeferredNode();
      children[index++] = child;

      switch (child.getKind()) {
      case RecordedOrDeferredNode::Kind::Null:
        break;
      case RecordedOrDeferredNode::Kind::Recorded:
        llvm_unreachable("Children of deferred nodes must also be deferred");
        break;
      case RecordedOrDeferredNode::Kind::DeferredLayout:
        length +=
            static_cast<const DeferredLayoutNode *>(child.getOpaque())->Length;
        break;
      case RecordedOrDeferredNode::Kind::DeferredToken:
        length += static_cast<const DeferredTokenNode *>(child.getOpaque())
                      ->getLength();
        break;
      }
    }

    return new (DeferredNodeAllocator) DeferredLayoutNode(k, children, length);
  }

  OpaqueSyntaxNode recordDeferredToken(OpaqueSyntaxNode deferred) override {
    auto Data = static_cast<const DeferredTokenNode *>(deferred);
    if (Data->IsMissing) {
      return recordMissingToken(Data->TokenKind, Data->Range.getStart());
    } else {
      return recordToken(Data->TokenKind, Data->LeadingTrivia,
                         Data->TrailingTrivia, Data->Range);
    }
  }

  OpaqueSyntaxNode recordDeferredLayout(OpaqueSyntaxNode deferred) override {
    auto Data = static_cast<const DeferredLayoutNode *>(deferred);

    auto childrenStore =
        DeferredNodeAllocator.Allocate<OpaqueSyntaxNode>(Data->Children.size());
    MutableArrayRef<OpaqueSyntaxNode> children =
        llvm::makeMutableArrayRef(childrenStore, Data->Children.size());

    for (size_t i = 0; i < Data->Children.size(); ++i) {
      auto Child = Data->Children[i];
      switch (Child.getKind()) {
      case RecordedOrDeferredNode::Kind::Null:
        children[i] = Child.getOpaque();
        break;
      case RecordedOrDeferredNode::Kind::Recorded:
        llvm_unreachable("Children of deferred nodes must also be deferred");
        break;
      case RecordedOrDeferredNode::Kind::DeferredLayout:
        children[i] = recordDeferredLayout(Child.getOpaque());
        break;
      case RecordedOrDeferredNode::Kind::DeferredToken:
        children[i] = recordDeferredToken(Child.getOpaque());
        break;
      }
    }
    return recordRawSyntax(Data->Kind, children);
  }

  DeferredNodeInfo getDeferredChild(OpaqueSyntaxNode node,
                                    size_t ChildIndex) const override {
    auto Data = static_cast<const DeferredLayoutNode *>(node);
    auto Child = Data->Children[ChildIndex];
    switch (Child.getKind()) {
    case RecordedOrDeferredNode::Kind::Null:
      return DeferredNodeInfo(
          RecordedOrDeferredNode(nullptr, RecordedOrDeferredNode::Kind::Null),
          syntax::SyntaxKind::Unknown, tok::NUM_TOKENS,
          /*IsMissing=*/false);
    case RecordedOrDeferredNode::Kind::Recorded:
      llvm_unreachable("Children of deferred nodes must also be deferred");
      break;
    case RecordedOrDeferredNode::Kind::DeferredLayout: {
      auto ChildData =
          static_cast<const DeferredLayoutNode *>(Child.getOpaque());
      return DeferredNodeInfo(
          RecordedOrDeferredNode(ChildData,
                                 RecordedOrDeferredNode::Kind::DeferredLayout),
          ChildData->Kind, tok::NUM_TOKENS,
          /*IsMissing=*/false);
    }
    case RecordedOrDeferredNode::Kind::DeferredToken: {
      auto ChildData =
          static_cast<const DeferredTokenNode *>(Child.getOpaque());
      return DeferredNodeInfo(
          RecordedOrDeferredNode(ChildData,
                                 RecordedOrDeferredNode::Kind::DeferredToken),
          syntax::SyntaxKind::Token, ChildData->TokenKind,
          ChildData->IsMissing);
    }
    }
  }

  CharSourceRange getDeferredChildRange(OpaqueSyntaxNode node,
                                        size_t ChildIndex,
                                        SourceLoc StartLoc) const override {
    auto Data = static_cast<const DeferredLayoutNode *>(node);

    // Compute the start offset of the child node by advancing StartLoc by the
    // length of all previous child nodes.
    for (unsigned i = 0; i < ChildIndex; ++i) {
      auto Child = Data->Children[i];
      switch (Child.getKind()) {
      case RecordedOrDeferredNode::Kind::Null:
        break;
      case RecordedOrDeferredNode::Kind::Recorded:
        llvm_unreachable("Children of deferred nodes must also be deferred");
      case RecordedOrDeferredNode::Kind::DeferredLayout:
        StartLoc = StartLoc.getAdvancedLoc(
            static_cast<const DeferredLayoutNode *>(Child.getOpaque())->Length);
        break;
      case RecordedOrDeferredNode::Kind::DeferredToken:
        StartLoc = StartLoc.getAdvancedLoc(
            static_cast<const DeferredTokenNode *>(Child.getOpaque())
                ->getLength());
        break;
      }
    }

    auto Child = Data->Children[ChildIndex];
    switch (Child.getKind()) {
    case RecordedOrDeferredNode::Kind::Null:
      return CharSourceRange(StartLoc, /*Length=*/0);
    case RecordedOrDeferredNode::Kind::Recorded:
      llvm_unreachable("Children of deferred nodes must also be deferred");
      break;
    case RecordedOrDeferredNode::Kind::DeferredLayout: {
      auto ChildData = static_cast<const DeferredLayoutNode *>(Child.getOpaque());
      return CharSourceRange(StartLoc, ChildData->Length);
    }
    case RecordedOrDeferredNode::Kind::DeferredToken: {
      auto ChildData = static_cast<const DeferredTokenNode *>(Child.getOpaque());
      assert(ChildData->Range.getStart() == StartLoc &&
             "Something broken in our StartLoc computation?");
      return ChildData->Range;
    }
    }
  }

  size_t getDeferredNumChildren(OpaqueSyntaxNode node) override {
    auto Data = static_cast<const DeferredLayoutNode *>(node);
    return Data->Children.size();
  }
};

static swiftparser_diagnostic_severity_t getSeverity(DiagnosticKind Kind) {
  switch (Kind) {
  case swift::DiagnosticKind::Error:
    return SWIFTPARSER_DIAGNOSTIC_SEVERITY_ERROR;
  case swift::DiagnosticKind::Warning:
    return SWIFTPARSER_DIAGNOSTIC_SEVERITY_WARNING;
  case swift::DiagnosticKind::Note:
    return SWIFTPARSER_DIAGNOSTIC_SEVERITY_NOTE;
  default:
    llvm_unreachable("unrecognized diagnostic kind.");
  }
}

struct DiagnosticDetail {
  const char* Message;
  unsigned Offset;
  std::vector<CRange> CRanges;
  swiftparser_diagnostic_severity_t Severity;
  std::vector<swiftparse_diagnostic_fixit_t> AllFixits;
};

struct SynParserDiagConsumer: public DiagnosticConsumer {
  SynParser &Parser;
  const unsigned BufferID;
  SynParserDiagConsumer(SynParser &Parser, unsigned BufferID):
    Parser(Parser), BufferID(BufferID) {}
  void handleDiagnostic(SourceManager &SM,
                        const DiagnosticInfo &Info) override {
    assert(Info.Kind != DiagnosticKind::Remark &&
           "Shouldn't see this in parser.");
    // The buffer where all char* will point into.
    llvm::SmallString<256> Buffer;
    auto getCurrentText = [&]() -> const char* {
      return Buffer.data() + Buffer.size();
    };
    DiagnosticDetail Result;
    Result.Severity = getSeverity(Info.Kind);
    Result.Offset = getByteOffset(Info.Loc, SM, BufferID);

    // Terminate each printed text with 0 so the client-side can use char* directly.
    char NullTerm = '\0';
    {
      // Print the error message to buffer and record it.
      llvm::raw_svector_ostream OS(Buffer);
      Result.Message = getCurrentText();
      DiagnosticEngine::formatDiagnosticText(OS, Info.FormatString,
                                             Info.FormatArgs);
      OS << NullTerm;
    }
    for (auto R: Info.Ranges) {
      Result.CRanges.emplace_back();
      initCRange(Result.CRanges.back(), R, SM, BufferID);
    }
    for (auto Fixit: Info.FixIts) {
      Result.AllFixits.push_back({CRange(), getCurrentText()});
      initCRange(Result.AllFixits.back().range, Fixit.getRange(), SM, BufferID);
      llvm::raw_svector_ostream OS(Buffer);
      OS << Fixit.getText() << NullTerm;
    }
    Parser.getDiagnosticHandler()(static_cast<void*>(&Result));
  }
};

swiftparse_client_node_t SynParser::parse(const char *source, size_t len) {
  SourceManager SM;
  unsigned bufID = SM.addNewSourceBuffer(llvm::MemoryBuffer::getMemBuffer(
      StringRef(source, len), "syntax_parse_source"));
  LangOptions langOpts;
  langOpts.BuildSyntaxTree = true;
  langOpts.ParseForSyntaxTreeOnly = true;
  langOpts.CollectParsedToken = false;
  // Disable name lookups during parsing.
  // Not ready yet:
  // langOpts.EnableASTScopeLookup = true;

  auto parseActions =
    std::make_shared<CLibParseActions>(*this, SM, bufID);
  // We have to use SourceFileKind::Main to avoid diagnostics like
  // illegal_top_level_expr
  ParserUnit PU(SM, SourceFileKind::Main, bufID, langOpts, TypeCheckerOptions(),
                SILOptions(), "syntax_parse_module", std::move(parseActions),
                /*SyntaxCache=*/nullptr);
  std::unique_ptr<SynParserDiagConsumer> pConsumer;
  if (DiagHandler) {
    pConsumer = std::make_unique<SynParserDiagConsumer>(*this, bufID);
    PU.getDiagnosticEngine().addConsumer(*pConsumer);
  }
  return const_cast<swiftparse_client_node_t>(PU.parse());
}
}
//===--- C API ------------------------------------------------------------===//

swiftparse_parser_t
swiftparse_parser_create(void) {
  return new SynParser();
}

void
swiftparse_parser_dispose(swiftparse_parser_t c_parser) {
  SynParser *parser = static_cast<SynParser*>(c_parser);
  delete parser;
}

void
swiftparse_parser_set_node_handler(swiftparse_parser_t c_parser,
                                   swiftparse_node_handler_t hdl) {
  SynParser *parser = static_cast<SynParser*>(c_parser);
  parser->setNodeHandler(hdl);
}

void
swiftparse_parser_set_node_lookup(swiftparse_parser_t c_parser,
                                  swiftparse_node_lookup_t lookup) {
  SynParser *parser = static_cast<SynParser*>(c_parser);
  parser->setNodeLookup(lookup);
}

swiftparse_client_node_t swiftparse_parse_string(swiftparse_parser_t c_parser,
                                                 const char *source,
                                                 size_t len) {
  SynParser *parser = static_cast<SynParser*>(c_parser);
  return parser->parse(source, len);
}

const char* swiftparse_syntax_structure_versioning_identifier(void) {
  return getSyntaxStructureVersioningIdentifier();
}

//===--------------------- C API for diagnostics -------------------------====//

void
swiftparse_parser_set_diagnostic_handler(swiftparse_parser_t c_parser,
                                         swiftparse_diagnostic_handler_t hdl) {
  SynParser *parser = static_cast<SynParser*>(c_parser);
  parser->setDiagnosticHandler(hdl);
}

const char* swiftparse_diagnostic_get_message(swiftparser_diagnostic_t diag) {
  return static_cast<const DiagnosticDetail*>(diag)->Message;
}

unsigned swiftparse_diagnostic_get_fixit_count(swiftparser_diagnostic_t diag) {
  return static_cast<const DiagnosticDetail*>(diag)->AllFixits.size();
}

swiftparse_diagnostic_fixit_t
swiftparse_diagnostic_get_fixit(swiftparser_diagnostic_t diag, unsigned idx) {
  auto allFixits = static_cast<const DiagnosticDetail*>(diag)->AllFixits;
  assert(idx < allFixits.size());
  return allFixits[idx];
}

unsigned swiftparse_diagnostic_get_range_count(swiftparser_diagnostic_t diag) {
  return static_cast<const DiagnosticDetail*>(diag)->CRanges.size();
}

swiftparse_range_t
swiftparse_diagnostic_get_range(swiftparser_diagnostic_t diag, unsigned idx) {
  return static_cast<const DiagnosticDetail*>(diag)->CRanges[idx];
}

swiftparser_diagnostic_severity_t
swiftparse_diagnostic_get_severity(swiftparser_diagnostic_t diag) {
  return static_cast<const DiagnosticDetail*>(diag)->Severity;
}

unsigned swiftparse_diagnostic_get_source_loc(swiftparser_diagnostic_t diag) {
  return static_cast<const DiagnosticDetail*>(diag)->Offset;
}