//===------------- IncrementalRanges.cpp - Generates swiftdeps files
//---------===//
//
// 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
//
//===----------------------------------------------------------------------===//

// These are the definitions for managing serializable source locations so that
// the frontend and the driver can implement incremental compilation based on
// source ranges.

#include "swift/AST/IncrementalRanges.h"
#include "swift/AST/ASTWalker.h"
#include "swift/AST/Decl.h"
#include "swift/AST/DiagnosticEngine.h"
#include "swift/AST/DiagnosticsCommon.h"
#include "swift/AST/DiagnosticsFrontend.h"
#include "swift/AST/FileSystem.h"
#include "swift/AST/SourceFile.h"
#include "swift/Basic/SourceManager.h"
#include "swift/Parse/Lexer.h"
#include "llvm/Support/YAMLParser.h"

using namespace swift;
using namespace incremental_ranges;

//==============================================================================
// MARK: SerializableSourceLocation
//==============================================================================

SerializableSourceLocation::SerializableSourceLocation(
    const SourceLoc loc, const SourceManager &SM) {
  auto lc = SM.getLineAndColumn(loc);
  line = lc.first;
  column = lc.second;
}

const SerializableSourceLocation SerializableSourceLocation::endOfAnyFile = {
    ~decltype(line)(0), 0};

void SerializableSourceLocation::print(raw_ostream &out) const {
  out << line << ":" << column;
}
void SerializableSourceLocation::dump() const { print(llvm::errs()); }

//==============================================================================
// MARK: SerializableSourceRange
//==============================================================================

SerializableSourceRange::SerializableSourceRange(
    SerializableSourceLocation start, SerializableSourceLocation end)
    : start(start), end(end) {
#ifndef NDEBUG
  if (!(start <= end)) {
    llvm::errs() << "*** Error: creating backwards SerializableSourceRange: [";
    start.print(llvm::errs());
    llvm::errs() << " -- ";
    end.print(llvm::errs());
    llvm::errs() << ")\n";
    assert(false && "Detected backwards SerializableSourceRange");
  }
#endif
}

SerializableSourceRange::SerializableSourceRange(const CharSourceRange r,
                                                 const SourceManager &SM)
    : start(SerializableSourceLocation(r.getStart(), SM)),
      end(SerializableSourceLocation(r.getEnd(), SM)) {}

const SerializableSourceRange SerializableSourceRange::wholeFile = {
    {0, 0}, SerializableSourceLocation::endOfAnyFile};

Ranges SerializableSourceRange::RangesForWholeFile() {
  assert(wholeFile.end.line && "Ensure initialization happens");
  return {wholeFile};
}

bool SerializableSourceRange::properlyPreceeds(
    const SerializableSourceRange &other) const {
  return end <= other.start;
}

bool SerializableSourceRange::isProperlySorted(
    ArrayRef<SerializableSourceRange> ranges) {
  Optional<SerializableSourceRange> lastRange;
  for (const auto &thisRange : ranges) {
    if (!lastRange)
      lastRange = thisRange;
    else if (!lastRange->properlyPreceeds(thisRange))
      return false;
  }
  return true;
}

bool SerializableSourceRange::isImproperSubsetOf(
    const SerializableSourceRange &superset) const {
  return superset.start <= start && end <= superset.end;
}

Optional<SerializableSourceRange> SerializableSourceRange::findOutlierIfAny(
    ArrayRef<SerializableSourceRange> subset,
    ArrayRef<SerializableSourceRange> superset) {
  // TODO: could optimize this by exploiting sortedness of the arrays:
  // i.e. could skip searching the start of the superset
  for (const auto &subsetRange : subset) {
    const bool isSubsetRangeContained = subsetRange.isImproperSubsetOfAny(superset);
    if (!isSubsetRangeContained)
      return subsetRange;
  }
  return None;
}

Ranges SerializableSourceRange::findAllOutliers(
    ArrayRef<SerializableSourceRange> subset,
    ArrayRef<SerializableSourceRange> superset) {
  // TODO:  optimize with slice of superset
  Ranges outliers;
  std::copy_if(subset.begin(), subset.end(), std::back_inserter(outliers),
               [&](const SerializableSourceRange &r) {
                 return !r.isImproperSubsetOfAny(superset);
               });
  return outliers;
}

bool SerializableSourceRange::isImproperSubsetOfAny(
    ArrayRef<SerializableSourceRange> supersetRanges) const {
  assert(isProperlySorted(supersetRanges) && "required for binary search");
  const auto firstRangeInSupersetNotBeforeSub =
      std::lower_bound(supersetRanges.begin(), supersetRanges.end(), *this,
                       [](const SerializableSourceRange &superRange,
                          const SerializableSourceRange &subsetRange) {
                         return superRange.properlyPreceeds(subsetRange);
                       });
  const bool result =
      firstRangeInSupersetNotBeforeSub != supersetRanges.end() &&
      isImproperSubsetOf(*firstRangeInSupersetNotBeforeSub);

  // slow if input is too big
  assert((supersetRanges.size() >= 5 ||
          result == isImproperSubsetOfAnySlowlyAndSimply(supersetRanges)) &&
         "Check against reference");

  return result;
}

bool SerializableSourceRange::isImproperSubsetOfAnySlowlyAndSimply(
    ArrayRef<SerializableSourceRange> supersetRanges) const {
  return llvm::any_of(supersetRanges,
                      [&](const SerializableSourceRange &superset) {
                        return isImproperSubsetOf(superset);
                      });
}

std::string SerializableSourceRange::printString() const {
  std::string result;
  llvm::raw_string_ostream out(result);
  print(out);
  return out.str();
}

void SerializableSourceRange::print(raw_ostream &out) const {
  out << "[";
  start.print(out);
  out << "--";
  end.print(out);
  out << ")";
}
void SerializableSourceRange::dump() const { print(llvm::errs()); }

//==============================================================================
// MARK: SwiftRangesEmitter
//==============================================================================

bool SwiftRangesEmitter::emit() const {
  const bool hadError =
      withOutputFile(diags, outputPath, [&](llvm::raw_pwrite_stream &out) {
        out << SwiftRangesFileContents::header;
        emitRanges(out);
        return false;
      });
  if (!hadError)
    return false;
  diags.diagnose(SourceLoc(), diag::error_unable_to_write_swift_ranges_file,
                 outputPath, "Output error");
  return true;
}

void SwiftRangesEmitter::emitRanges(llvm::raw_ostream &out) const {
  SwiftRangesFileContents wholeFileContents(
      collectSortedSerializedNoninlinableFunctionBodies());
  llvm::yaml::Output yamlWriter(out);
  yamlWriter << wholeFileContents;
}

Ranges
SwiftRangesEmitter::collectSortedSerializedNoninlinableFunctionBodies() const {
  return serializeRanges(
      coalesceSortedRanges(sortRanges(collectNoninlinableFunctionBodies())));
}

std::vector<CharSourceRange>
SwiftRangesEmitter::collectNoninlinableFunctionBodies() const {
  struct FnBodyCollector : ASTWalker {
    const SourceManager &SM;
    FnBodyCollector(const SourceManager &SM) : SM(SM) {}

    std::vector<CharSourceRange> ranges;
    bool walkToDeclPre(Decl *D) override {
      if (const auto *AFD = dyn_cast<AbstractFunctionDecl>(D)) {
        // If you change an accessor body you might change the inferred
        // type, and the change might propagate, so exclude them from local
        // change ranges.
        // Also rule out implicit constructors a fortiori.
        if (!isa<AccessorDecl>(AFD) && !AFD->isImplicit() &&
            !AFD->getAttrs().hasAttribute<InlinableAttr>()) {
          auto sr = AFD->getBodySourceRange();
          if (sr.isValid())
            ranges.push_back(Lexer::getCharSourceRangeFromSourceRange(SM, sr));
        }
        return false;
      }
      return true;
    }
  };
  FnBodyCollector collector(sourceMgr);
  primaryFile->walk(collector);
  return collector.ranges;
}

std::vector<CharSourceRange>
SwiftRangesEmitter::sortRanges(std::vector<CharSourceRange> ranges) const {
  std::sort(ranges.begin(), ranges.end(),
            [&](const CharSourceRange &lhs, const CharSourceRange &rhs) {
              return sourceMgr.isBeforeInBuffer(lhs.getStart(), rhs.getStart());
            });
  return ranges;
}

std::vector<CharSourceRange> SwiftRangesEmitter::coalesceSortedRanges(
    std::vector<CharSourceRange> ranges) const {
  if (ranges.empty())
    return ranges;
  auto toBeWidened = ranges.begin();
  auto candidate = toBeWidened + 1;
  while (candidate < ranges.end()) {
    if (isImmediatelyBeforeOrOverlapping(*toBeWidened, *candidate))
      toBeWidened->widen(*candidate++);
    else
      *++toBeWidened = *candidate++;
  }
  ranges.erase(toBeWidened + 1, ranges.end());
  return ranges;
}

std::vector<SerializableSourceRange>
SwiftRangesEmitter::serializeRanges(std::vector<CharSourceRange> ranges) const {
  std::vector<SerializableSourceRange> result;
  for (const auto r : ranges)
    result.push_back(SerializableSourceRange(r, sourceMgr));
  return result;
}

bool SwiftRangesEmitter::isImmediatelyBeforeOrOverlapping(
    CharSourceRange prev, CharSourceRange next) const {
  // TODO: investigate returning true if only white space intervenes.
  // Would be more work here, but less work downstream.
  return !sourceMgr.isBeforeInBuffer(prev.getEnd(), next.getStart());
}

//==============================================================================
// MARK: CompiledSource
//==============================================================================

bool CompiledSourceEmitter::emit() {
  auto const bufID = primaryFile->getBufferID();
  if (!bufID.hasValue()) {
    diags.diagnose(SourceLoc(),
                   diag::error_unable_to_write_compiled_source_file, outputPath,
                   "No buffer");
    return true;
  }
  const bool hadError =
      withOutputFile(diags, outputPath, [&](llvm::raw_pwrite_stream &out) {
        out << sourceMgr.getEntireTextForBuffer(bufID.getValue());
        return false;
      });
  if (!hadError)
    return false;
  diags.diagnose(SourceLoc(), diag::error_unable_to_write_compiled_source_file,
                 outputPath, "Output error");
  return true;
}

//==============================================================================
// MARK: SwiftRangesFileContents
//==============================================================================

void SwiftRangesFileContents::dump(const StringRef primaryInputFilename) const {
  llvm::errs() << "\n*** Swift range file contents for '"
               << primaryInputFilename << "': ***\n";
  llvm::yaml::Output dumper(llvm::errs());
  dumper << *const_cast<SwiftRangesFileContents *>(this);
}