//===- SourceMgr.cpp - Manager for Simple Source Buffers & Diagnostics ----===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the SourceMgr class.  This class is used as a simple
// substrate for diagnostics, #include handling, and other low level things for
// simple parsers.
//
//===----------------------------------------------------------------------===//

#include "llvm/Support/SourceMgr.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Support/Locale.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/raw_ostream.h"
#include <system_error>
using namespace llvm;

static const size_t TabStop = 8;

namespace {
  struct LineNoCacheTy {
    unsigned LastQueryBufferID;
    const char *LastQuery;
    unsigned LineNoOfQuery;
  };
}

static LineNoCacheTy *getCache(void *Ptr) {
  return (LineNoCacheTy*)Ptr;
}


SourceMgr::~SourceMgr() {
  // Delete the line # cache if allocated.
  if (LineNoCacheTy *Cache = getCache(LineNoCache))
    delete Cache;
}

unsigned SourceMgr::AddIncludeFile(const std::string &Filename,
                                   SMLoc IncludeLoc,
                                   std::string &IncludedFile) {
  IncludedFile = Filename;
  ErrorOr<std::unique_ptr<MemoryBuffer>> NewBufOrErr =
    MemoryBuffer::getFile(IncludedFile);

  // If the file didn't exist directly, see if it's in an include path.
  for (unsigned i = 0, e = IncludeDirectories.size(); i != e && !NewBufOrErr;
       ++i) {
    IncludedFile =
        IncludeDirectories[i] + sys::path::get_separator().data() + Filename;
    NewBufOrErr = MemoryBuffer::getFile(IncludedFile);
  }

  if (!NewBufOrErr)
    return 0;

  return AddNewSourceBuffer(std::move(*NewBufOrErr), IncludeLoc);
}

unsigned SourceMgr::FindBufferContainingLoc(SMLoc Loc) const {
  for (unsigned i = 0, e = Buffers.size(); i != e; ++i)
    if (Loc.getPointer() >= Buffers[i].Buffer->getBufferStart() &&
        // Use <= here so that a pointer to the null at the end of the buffer
        // is included as part of the buffer.
        Loc.getPointer() <= Buffers[i].Buffer->getBufferEnd())
      return i + 1;
  return 0;
}

std::pair<unsigned, unsigned>
SourceMgr::getLineAndColumn(SMLoc Loc, unsigned BufferID) const {
  if (!BufferID)
    BufferID = FindBufferContainingLoc(Loc);
  assert(BufferID && "Invalid Location!");

  const MemoryBuffer *Buff = getMemoryBuffer(BufferID);

  // Count the number of \n's between the start of the file and the specified
  // location.
  unsigned LineNo = 1;

  const char *BufStart = Buff->getBufferStart();
  const char *Ptr = BufStart;

  // If we have a line number cache, and if the query is to a later point in the
  // same file, start searching from the last query location.  This optimizes
  // for the case when multiple diagnostics come out of one file in order.
  if (LineNoCacheTy *Cache = getCache(LineNoCache))
    if (Cache->LastQueryBufferID == BufferID &&
        Cache->LastQuery <= Loc.getPointer()) {
      Ptr = Cache->LastQuery;
      LineNo = Cache->LineNoOfQuery;
    }

  // Scan for the location being queried, keeping track of the number of lines
  // we see.
  for (; SMLoc::getFromPointer(Ptr) != Loc; ++Ptr)
    if (*Ptr == '\n') ++LineNo;

  // Allocate the line number cache if it doesn't exist.
  if (!LineNoCache)
    LineNoCache = new LineNoCacheTy();

  // Update the line # cache.
  LineNoCacheTy &Cache = *getCache(LineNoCache);
  Cache.LastQueryBufferID = BufferID;
  Cache.LastQuery = Ptr;
  Cache.LineNoOfQuery = LineNo;
  
  size_t NewlineOffs = StringRef(BufStart, Ptr-BufStart).find_last_of("\n\r");
  if (NewlineOffs == StringRef::npos) NewlineOffs = ~(size_t)0;
  return std::make_pair(LineNo, Ptr-BufStart-NewlineOffs);
}

void SourceMgr::PrintIncludeStack(SMLoc IncludeLoc, raw_ostream &OS) const {
  if (IncludeLoc == SMLoc()) return;  // Top of stack.

  unsigned CurBuf = FindBufferContainingLoc(IncludeLoc);
  assert(CurBuf && "Invalid or unspecified location!");

  PrintIncludeStack(getBufferInfo(CurBuf).IncludeLoc, OS);

  OS << "Included from "
     << getBufferInfo(CurBuf).Buffer->getBufferIdentifier()
     << ":" << FindLineNumber(IncludeLoc, CurBuf) << ":\n";
}


SMDiagnostic SourceMgr::GetMessage(SMLoc Loc, SourceMgr::DiagKind Kind,
                                   const Twine &Msg,
                                   ArrayRef<SMRange> Ranges,
                                   ArrayRef<SMFixIt> FixIts) const {

  // First thing to do: find the current buffer containing the specified
  // location to pull out the source line.
  SmallVector<std::pair<unsigned, unsigned>, 4> ColRanges;
  std::pair<unsigned, unsigned> LineAndCol;
  const char *BufferID = "<unknown>";
  std::string LineStr;
  
  if (Loc.isValid()) {
    unsigned CurBuf = FindBufferContainingLoc(Loc);
    assert(CurBuf && "Invalid or unspecified location!");

    const MemoryBuffer *CurMB = getMemoryBuffer(CurBuf);
    BufferID = CurMB->getBufferIdentifier();
    
    // Scan backward to find the start of the line.
    const char *LineStart = Loc.getPointer();
    const char *BufStart = CurMB->getBufferStart();
    while (LineStart != BufStart && LineStart[-1] != '\n' &&
           LineStart[-1] != '\r')
      --LineStart;

    // Get the end of the line.
    const char *LineEnd = Loc.getPointer();
    const char *BufEnd = CurMB->getBufferEnd();
    while (LineEnd != BufEnd && LineEnd[0] != '\n' && LineEnd[0] != '\r')
      ++LineEnd;
    LineStr = std::string(LineStart, LineEnd);

    // Convert any ranges to column ranges that only intersect the line of the
    // location.
    for (unsigned i = 0, e = Ranges.size(); i != e; ++i) {
      SMRange R = Ranges[i];
      if (!R.isValid()) continue;
      
      // If the line doesn't contain any part of the range, then ignore it.
      if (R.Start.getPointer() > LineEnd || R.End.getPointer() < LineStart)
        continue;
     
      // Ignore pieces of the range that go onto other lines.
      if (R.Start.getPointer() < LineStart)
        R.Start = SMLoc::getFromPointer(LineStart);
      if (R.End.getPointer() > LineEnd)
        R.End = SMLoc::getFromPointer(LineEnd);
      
      // Translate from SMLoc ranges to column ranges.
      // FIXME: Handle multibyte characters.
      ColRanges.push_back(std::make_pair(R.Start.getPointer()-LineStart,
                                         R.End.getPointer()-LineStart));
    }

    LineAndCol = getLineAndColumn(Loc, CurBuf);
  }
    
  return SMDiagnostic(*this, Loc, BufferID, LineAndCol.first,
                      LineAndCol.second-1, Kind, Msg.str(),
                      LineStr, ColRanges, FixIts);
}

void SourceMgr::PrintMessage(raw_ostream &OS, const SMDiagnostic &Diagnostic,
                             bool ShowColors) const {
  // Report the message with the diagnostic handler if present.
  if (DiagHandler) {
    DiagHandler(Diagnostic, DiagContext);
    return;
  }

  if (Diagnostic.getLoc().isValid()) {
    unsigned CurBuf = FindBufferContainingLoc(Diagnostic.getLoc());
    assert(CurBuf && "Invalid or unspecified location!");
    PrintIncludeStack(getBufferInfo(CurBuf).IncludeLoc, OS);
  }

  Diagnostic.print(nullptr, OS, ShowColors);
}

void SourceMgr::PrintMessage(raw_ostream &OS, SMLoc Loc,
                             SourceMgr::DiagKind Kind,
                             const Twine &Msg, ArrayRef<SMRange> Ranges,
                             ArrayRef<SMFixIt> FixIts, bool ShowColors) const {
  PrintMessage(OS, GetMessage(Loc, Kind, Msg, Ranges, FixIts), ShowColors);
}

void SourceMgr::PrintMessage(SMLoc Loc, SourceMgr::DiagKind Kind,
                             const Twine &Msg, ArrayRef<SMRange> Ranges,
                             ArrayRef<SMFixIt> FixIts, bool ShowColors) const {
  PrintMessage(llvm::errs(), Loc, Kind, Msg, Ranges, FixIts, ShowColors);
}

//===----------------------------------------------------------------------===//
// SMDiagnostic Implementation
//===----------------------------------------------------------------------===//

SMDiagnostic::SMDiagnostic(const SourceMgr &sm, SMLoc L, StringRef FN,
                           int Line, int Col, SourceMgr::DiagKind Kind,
                           StringRef Msg, StringRef LineStr,
                           ArrayRef<std::pair<unsigned,unsigned> > Ranges,
                           ArrayRef<SMFixIt> Hints)
  : SM(&sm), Loc(L), Filename(FN), LineNo(Line), ColumnNo(Col), Kind(Kind),
    Message(Msg), LineContents(LineStr), Ranges(Ranges.vec()),
    FixIts(Hints.begin(), Hints.end()) {
  std::sort(FixIts.begin(), FixIts.end());
}

static void buildFixItLine(std::string &CaretLine, std::string &FixItLine,
                           ArrayRef<SMFixIt> FixIts, ArrayRef<char> SourceLine){
  if (FixIts.empty())
    return;

  const char *LineStart = SourceLine.begin();
  const char *LineEnd = SourceLine.end();

  size_t PrevHintEndCol = 0;

  for (ArrayRef<SMFixIt>::iterator I = FixIts.begin(), E = FixIts.end();
       I != E; ++I) {
    // If the fixit contains a newline or tab, ignore it.
    if (I->getText().find_first_of("\n\r\t") != StringRef::npos)
      continue;

    SMRange R = I->getRange();

    // If the line doesn't contain any part of the range, then ignore it.
    if (R.Start.getPointer() > LineEnd || R.End.getPointer() < LineStart)
      continue;

    // Translate from SMLoc to column.
    // Ignore pieces of the range that go onto other lines.
    // FIXME: Handle multibyte characters in the source line.
    unsigned FirstCol;
    if (R.Start.getPointer() < LineStart)
      FirstCol = 0;
    else
      FirstCol = R.Start.getPointer() - LineStart;

    // If we inserted a long previous hint, push this one forwards, and add
    // an extra space to show that this is not part of the previous
    // completion. This is sort of the best we can do when two hints appear
    // to overlap.
    //
    // Note that if this hint is located immediately after the previous
    // hint, no space will be added, since the location is more important.
    unsigned HintCol = FirstCol;
    if (HintCol < PrevHintEndCol)
      HintCol = PrevHintEndCol + 1;

    // FIXME: This assertion is intended to catch unintended use of multibyte
    // characters in fixits. If we decide to do this, we'll have to track
    // separate byte widths for the source and fixit lines.
    assert((size_t)llvm::sys::locale::columnWidth(I->getText()) ==
           I->getText().size());

    // This relies on one byte per column in our fixit hints.
    unsigned LastColumnModified = HintCol + I->getText().size();
    if (LastColumnModified > FixItLine.size())
      FixItLine.resize(LastColumnModified, ' ');

    std::copy(I->getText().begin(), I->getText().end(),
              FixItLine.begin() + HintCol);

    PrevHintEndCol = LastColumnModified;

    // For replacements, mark the removal range with '~'.
    // FIXME: Handle multibyte characters in the source line.
    unsigned LastCol;
    if (R.End.getPointer() >= LineEnd)
      LastCol = LineEnd - LineStart;
    else
      LastCol = R.End.getPointer() - LineStart;

    std::fill(&CaretLine[FirstCol], &CaretLine[LastCol], '~');
  }
}

static void printSourceLine(raw_ostream &S, StringRef LineContents) {
  // Print out the source line one character at a time, so we can expand tabs.
  for (unsigned i = 0, e = LineContents.size(), OutCol = 0; i != e; ++i) {
    if (LineContents[i] != '\t') {
      S << LineContents[i];
      ++OutCol;
      continue;
    }

    // If we have a tab, emit at least one space, then round up to 8 columns.
    do {
      S << ' ';
      ++OutCol;
    } while ((OutCol % TabStop) != 0);
  }
  S << '\n';
}

static bool isNonASCII(char c) {
  return c & 0x80;
}

void SMDiagnostic::print(const char *ProgName, raw_ostream &S,
                         bool ShowColors) const {
  // Display colors only if OS supports colors.
  ShowColors &= S.has_colors();

  if (ShowColors)
    S.changeColor(raw_ostream::SAVEDCOLOR, true);

  if (ProgName && ProgName[0])
    S << ProgName << ": ";

  if (!Filename.empty()) {
    if (Filename == "-")
      S << "<stdin>";
    else
      S << Filename;

    if (LineNo != -1) {
      S << ':' << LineNo;
      if (ColumnNo != -1)
        S << ':' << (ColumnNo+1);
    }
    S << ": ";
  }

  switch (Kind) {
  case SourceMgr::DK_Error:
    if (ShowColors)
      S.changeColor(raw_ostream::RED, true);
    S << "error: ";
    break;
  case SourceMgr::DK_Warning:
    if (ShowColors)
      S.changeColor(raw_ostream::MAGENTA, true);
    S << "warning: ";
    break;
  case SourceMgr::DK_Note:
    if (ShowColors)
      S.changeColor(raw_ostream::BLACK, true);
    S << "note: ";
    break;
  }

  if (ShowColors) {
    S.resetColor();
    S.changeColor(raw_ostream::SAVEDCOLOR, true);
  }

  S << Message << '\n';

  if (ShowColors)
    S.resetColor();

  if (LineNo == -1 || ColumnNo == -1)
    return;

  // FIXME: If there are multibyte or multi-column characters in the source, all
  // our ranges will be wrong. To do this properly, we'll need a byte-to-column
  // map like Clang's TextDiagnostic. For now, we'll just handle tabs by
  // expanding them later, and bail out rather than show incorrect ranges and
  // misaligned fixits for any other odd characters.
  if (std::find_if(LineContents.begin(), LineContents.end(), isNonASCII) !=
      LineContents.end()) {
    printSourceLine(S, LineContents);
    return;
  }
  size_t NumColumns = LineContents.size();

  // Build the line with the caret and ranges.
  std::string CaretLine(NumColumns+1, ' ');
  
  // Expand any ranges.
  for (unsigned r = 0, e = Ranges.size(); r != e; ++r) {
    std::pair<unsigned, unsigned> R = Ranges[r];
    std::fill(&CaretLine[R.first],
              &CaretLine[std::min((size_t)R.second, CaretLine.size())],
              '~');
  }

  // Add any fix-its.
  // FIXME: Find the beginning of the line properly for multibyte characters.
  std::string FixItInsertionLine;
  buildFixItLine(CaretLine, FixItInsertionLine, FixIts,
                 makeArrayRef(Loc.getPointer() - ColumnNo,
                              LineContents.size()));

  // Finally, plop on the caret.
  if (unsigned(ColumnNo) <= NumColumns)
    CaretLine[ColumnNo] = '^';
  else 
    CaretLine[NumColumns] = '^';
  
  // ... and remove trailing whitespace so the output doesn't wrap for it.  We
  // know that the line isn't completely empty because it has the caret in it at
  // least.
  CaretLine.erase(CaretLine.find_last_not_of(' ')+1);
  
  printSourceLine(S, LineContents);

  if (ShowColors)
    S.changeColor(raw_ostream::GREEN, true);

  // Print out the caret line, matching tabs in the source line.
  for (unsigned i = 0, e = CaretLine.size(), OutCol = 0; i != e; ++i) {
    if (i >= LineContents.size() || LineContents[i] != '\t') {
      S << CaretLine[i];
      ++OutCol;
      continue;
    }
    
    // Okay, we have a tab.  Insert the appropriate number of characters.
    do {
      S << CaretLine[i];
      ++OutCol;
    } while ((OutCol % TabStop) != 0);
  }
  S << '\n';

  if (ShowColors)
    S.resetColor();

  // Print out the replacement line, matching tabs in the source line.
  if (FixItInsertionLine.empty())
    return;
  
  for (size_t i = 0, e = FixItInsertionLine.size(), OutCol = 0; i < e; ++i) {
    if (i >= LineContents.size() || LineContents[i] != '\t') {
      S << FixItInsertionLine[i];
      ++OutCol;
      continue;
    }

    // Okay, we have a tab.  Insert the appropriate number of characters.
    do {
      S << FixItInsertionLine[i];
      // FIXME: This is trying not to break up replacements, but then to re-sync
      // with the tabs between replacements. This will fail, though, if two
      // fix-it replacements are exactly adjacent, or if a fix-it contains a
      // space. Really we should be precomputing column widths, which we'll
      // need anyway for multibyte chars.
      if (FixItInsertionLine[i] != ' ')
        ++i;
      ++OutCol;
    } while (((OutCol % TabStop) != 0) && i != e);
  }
  S << '\n';
}