/*
 * Copyright 2000-2009 JetBrains s.r.o.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.intellij.openapi.vcs.ex;

import com.intellij.openapi.application.Application;
import com.intellij.openapi.application.ApplicationManager;
import com.intellij.openapi.command.undo.UndoConstants;
import com.intellij.openapi.diagnostic.Logger;
import com.intellij.openapi.editor.Document;
import com.intellij.openapi.editor.event.DocumentAdapter;
import com.intellij.openapi.editor.event.DocumentEvent;
import com.intellij.openapi.editor.impl.DocumentImpl;
import com.intellij.openapi.editor.impl.DocumentMarkupModel;
import com.intellij.openapi.editor.markup.*;
import com.intellij.openapi.fileEditor.FileDocumentManager;
import com.intellij.openapi.fileEditor.FileEditor;
import com.intellij.openapi.fileEditor.FileEditorManager;
import com.intellij.openapi.progress.ProcessCanceledException;
import com.intellij.openapi.project.Project;
import com.intellij.openapi.util.Key;
import com.intellij.openapi.util.TextRange;
import com.intellij.openapi.util.registry.Registry;
import com.intellij.openapi.util.text.StringUtil;
import com.intellij.openapi.vcs.VcsBundle;
import com.intellij.openapi.vcs.changes.VcsDirtyScopeManager;
import com.intellij.openapi.vcs.history.VcsRevisionNumber;
import com.intellij.openapi.vfs.VirtualFile;
import com.intellij.ui.EditorNotificationPanel;
import com.intellij.util.ExceptionUtil;
import com.intellij.util.containers.ContainerUtil;
import com.intellij.util.diff.FilesTooBigForDiffException;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

import javax.swing.*;
import java.util.*;

/**
 * @author irengrig
 *         author: lesya
 */
public class LineStatusTracker {
  private static final Logger LOG = Logger.getInstance("#com.intellij.openapi.vcs.ex.LineStatusTracker");
  private static final Key<CanNotCalculateDiffPanel> PANEL_KEY =
    new Key<CanNotCalculateDiffPanel>("LineStatusTracker.CanNotCalculateDiffPanel");

  private final Object myLock = new Object();
  private BaseLoadState myBaseLoaded;

  private final Document myDocument;
  private final Document myVcsDocument;

  private List<Range> myRanges;

  private final Project myProject;

  private MyDocumentListener myDocumentListener;

  private boolean mySuppressUpdate;
  private boolean myBulkUpdate;
  private final Application myApplication;
  @Nullable private RevisionPack myBaseRevisionNumber;
  private String myPreviousBaseRevision;
  private boolean myAnathemaThrown;
  private FileEditorManager myFileEditorManager;
  private final VcsDirtyScopeManager myVcsDirtyScopeManager;
  private final VirtualFile myVirtualFile;
  private boolean myReleased = false;

  private LineStatusTracker(@NotNull final Document document,
                            @NotNull final Document vcsDocument,
                            final Project project,
                            @Nullable final VirtualFile virtualFile) {
    myVirtualFile = virtualFile;
    myApplication = ApplicationManager.getApplication();
    myDocument = document;
    myVcsDocument = vcsDocument;
    myVcsDocument.putUserData(UndoConstants.DONT_RECORD_UNDO, Boolean.TRUE);
    myProject = project;
    myBaseLoaded = BaseLoadState.LOADING;
    myRanges = new ArrayList<Range>();
    myAnathemaThrown = false;
    myFileEditorManager = FileEditorManager.getInstance(myProject);
    myVcsDirtyScopeManager = VcsDirtyScopeManager.getInstance(myProject);
  }

  public void initialize(@NotNull final String vcsContent, @NotNull RevisionPack baseRevisionNumber) {
    ApplicationManager.getApplication().assertIsDispatchThread();

    synchronized (myLock) {
      try {
        if (myReleased) return;
        if (myBaseRevisionNumber != null && myBaseRevisionNumber.after(baseRevisionNumber)) return;

        myBaseRevisionNumber = baseRevisionNumber;
        myPreviousBaseRevision = null;

        myVcsDocument.setReadOnly(false);
        myVcsDocument.replaceString(0, myVcsDocument.getTextLength(), vcsContent);
        myVcsDocument.setReadOnly(true);
        reinstallRanges();

        if (myDocumentListener == null) {
          myDocumentListener = new MyDocumentListener();
          myDocument.addDocumentListener(myDocumentListener);
        }
      }
      finally {
        myBaseLoaded = BaseLoadState.LOADED;
      }
    }
  }

  public void useCachedBaseRevision(final RevisionPack number) {
    synchronized (myLock) {
      assert myBaseRevisionNumber != null;
      if (myPreviousBaseRevision == null || myBaseRevisionNumber.after(number)) return;
      initialize(myPreviousBaseRevision, number);
    }
  }

  public boolean canUseBaseRevision(final RevisionPack number) {
    synchronized (myLock) {
      return myBaseRevisionNumber != null && myBaseRevisionNumber.equals(number) && myPreviousBaseRevision != null;
    }
  }

  private void reinstallRanges() {
    myApplication.assertReadAccessAllowed();

    synchronized (myLock) {
      removeAnathema();
      removeHighlightersFromMarkupModel();
      try {
        myRanges = new RangesBuilder(myDocument, myVcsDocument).getRanges();
      }
      catch (FilesTooBigForDiffException e) {
        myRanges.clear();
        installAnathema();
        return;
      }
      for (final Range range : myRanges) {
        range.setHighlighter(createHighlighter(range));
      }
    }
  }

  private void removeAnathema() {
    if (!myAnathemaThrown) return;
    myAnathemaThrown = false;
    final FileEditor[] editors = myFileEditorManager.getEditors(myVirtualFile);
    for (FileEditor editor : editors) {
      final CanNotCalculateDiffPanel panel = editor.getUserData(PANEL_KEY);
      if (panel != null) {
        myFileEditorManager.removeTopComponent(editor, panel);
        editor.putUserData(PANEL_KEY, null);
      }
    }
  }

  @SuppressWarnings({"AutoBoxing"})
  private RangeHighlighter createHighlighter(final Range range) {
    LOG.assertTrue(!myReleased, "Already released");

    int first =
      range.getLine1() >= getLineCount(myDocument) ? myDocument.getTextLength() : myDocument.getLineStartOffset(range.getLine1());

    int second =
      range.getLine2() >= getLineCount(myDocument) ? myDocument.getTextLength() : myDocument.getLineStartOffset(range.getLine2());

    final RangeHighlighter highlighter = DocumentMarkupModel.forDocument(myDocument, myProject, true)
      .addRangeHighlighter(first, second, HighlighterLayer.FIRST - 1, null, HighlighterTargetArea.LINES_IN_RANGE);

    final TextAttributes attr = LineStatusTrackerDrawing.getAttributesFor(range);
    highlighter.setErrorStripeMarkColor(attr.getErrorStripeColor());
    highlighter.setThinErrorStripeMark(true);
    highlighter.setGreedyToLeft(true);
    highlighter.setGreedyToRight(true);
    highlighter.setLineMarkerRenderer(LineStatusTrackerDrawing.createRenderer(range, this));
    highlighter.setEditorFilter(MarkupEditorFilterFactory.createIsNotDiffFilter());

    final String tooltip;
    if (range.getLine1() == range.getLine2()) {
      if (range.getVcsLine1() + 1 == range.getVcsLine2()) {
        tooltip = VcsBundle.message("tooltip.text.line.before.deleted", range.getLine1() + 1);
      }
      else {
        tooltip = VcsBundle.message("tooltip.text.lines.before.deleted", range.getLine1() + 1, range.getVcsLine2() - range.getVcsLine1());
      }
    }
    else if (range.getLine1() + 1 == range.getLine2()) {
      tooltip = VcsBundle.message("tooltip.text.line.changed", range.getLine1() + 1);
    }
    else {
      tooltip = VcsBundle.message("tooltip.text.lines.changed", range.getLine1() + 1, range.getLine2());
    }

    highlighter.setErrorStripeTooltip(tooltip);
    return highlighter;
  }

  public void release() {
    synchronized (myLock) {
      if (myDocumentListener != null) {
        myDocument.removeDocumentListener(myDocumentListener);
      }
      removeAnathema();
      removeHighlightersFromMarkupModel();
      myReleased = true;
    }
  }

  public Document getDocument() {
    return myDocument;
  }

  public VirtualFile getVirtualFile() {
    return myVirtualFile;
  }

  public List<Range> getRanges() {
    myApplication.assertReadAccessAllowed();

    synchronized (myLock) {
      return myRanges;
    }
  }

  public Document getVcsDocument() {
    myApplication.assertIsDispatchThread();
    return myVcsDocument;
  }

  public void startBulkUpdate() {
    synchronized (myLock) {
      if (myReleased) return;

      myBulkUpdate = true;
      removeAnathema();
      removeHighlightersFromMarkupModel();
    }
  }

  private void removeHighlightersFromMarkupModel() {
    synchronized (myLock) {
      for (Range range : myRanges) {
        if (range.getHighlighter() != null) {
          range.getHighlighter().dispose();
        }
        range.invalidate();
      }
      myRanges.clear();
    }
  }

  public void finishBulkUpdate() {
    synchronized (myLock) {
      if (myReleased) return;

      myBulkUpdate = false;
      reinstallRanges();
    }
  }

  /**
   * @return true if was cleared and base revision contents load should be started
   * false -> load was already started; after contents is loaded,
   */
  public void resetForBaseRevisionLoad() {
    myApplication.assertReadAccessAllowed();

    synchronized (myLock) {
      // there can be multiple resets before init -> take from document only firts time -> when right after install(),
      // where myPreviousBaseRevision become null
      if (BaseLoadState.LOADED.equals(myBaseLoaded) && myPreviousBaseRevision == null) {
        myPreviousBaseRevision = myVcsDocument.getText();
      }
      myVcsDocument.setReadOnly(false);
      myVcsDocument.setText("");
      myVcsDocument.setReadOnly(true);
      removeAnathema();
      removeHighlightersFromMarkupModel();
      myBaseLoaded = BaseLoadState.LOADING;
    }
  }

  private class MyDocumentListener extends DocumentAdapter {
    // We have 3 document versions:
    // * VCS version
    // * before change
    // * after change

    private int myLine1;
    private int myBeforeChangedLines;
    private int myBeforeTotalLines;

    @Override
    public void beforeDocumentChange(DocumentEvent e) {
      myApplication.assertWriteAccessAllowed();

      synchronized (myLock) {
        if (myReleased) return;
        if (myBulkUpdate || mySuppressUpdate || myAnathemaThrown || BaseLoadState.LOADED != myBaseLoaded) return;
        assert myDocument == e.getDocument();

        try {
          myLine1 = myDocument.getLineNumber(e.getOffset());
          if (e.getOldLength() == 0) {
            myBeforeChangedLines = 1;
          }
          else {
            int line1 = myLine1;
            int line2 = myDocument.getLineNumber(e.getOffset() + e.getOldLength());
            myBeforeChangedLines = line2 - line1 + 1;
          }

          myBeforeTotalLines = getLineCount(myDocument);
        }
        catch (ProcessCanceledException ignore) {
        }
      }
    }

    @Override
    public void documentChanged(final DocumentEvent e) {
      myApplication.assertWriteAccessAllowed();

      synchronized (myLock) {
        if (myReleased) return;
        if (myBulkUpdate || mySuppressUpdate || myAnathemaThrown || BaseLoadState.LOADED != myBaseLoaded) return;
        assert myDocument == e.getDocument();

        int afterChangedLines;
        if (e.getNewLength() == 0) {
          afterChangedLines = 1;
        }
        else {
          int line1 = myLine1;
          int line2 = myDocument.getLineNumber(e.getOffset() + e.getNewLength());
          afterChangedLines = line2 - line1 + 1;
        }

        int linesShift = afterChangedLines - myBeforeChangedLines;

        int line1 = myLine1;
        int line2 = line1 + myBeforeChangedLines; // TODO: optimize some whole-line-changed cases

        int[] fixed = fixRanges(e, line1, line2);
        line1 = fixed[0];
        line2 = fixed[1];

        doUpdateRanges(line1, line2, linesShift, myBeforeTotalLines);
      }
    }
  }

  @NotNull
  private int[] fixRanges(@NotNull DocumentEvent e, int line1, int line2) {
    CharSequence document = myDocument.getCharsSequence();
    int offset = e.getOffset();

    if (e.getOldLength() == 0 && e.getNewLength() != 0) {
      if (StringUtil.endsWithChar(e.getNewFragment(), '\n') && isNewline(offset - 1, document)) {
        return new int[]{line1, line2 - 1};
      }
      if (StringUtil.startsWithChar(e.getNewFragment(), '\n') && isNewline(offset + e.getNewLength(), document)) {
        return new int[]{line1 + 1, line2};
      }
    }
    if (e.getOldLength() != 0 && e.getNewLength() == 0) {
      if (StringUtil.endsWithChar(e.getOldFragment(), '\n') && isNewline(offset - 1, document)) {
        return new int[]{line1, line2 - 1};
      }
      if (StringUtil.startsWithChar(e.getOldFragment(), '\n') && isNewline(offset + e.getNewLength(), document)) {
        return new int[]{line1 + 1, line2};
      }
    }

    return new int[]{line1, line2};
  }

  private static boolean isNewline(int offset, @NotNull CharSequence sequence) {
    if (offset < 0) return false;
    if (offset >= sequence.length()) return false;
    return sequence.charAt(offset) == '\n';
  }

  private void doUpdateRanges(int beforeChangedLine1,
                              int beforeChangedLine2,
                              int linesShift,
                              int beforeTotalLines) {
    List<Range> rangesBeforeChange = new ArrayList<Range>();
    List<Range> rangesAfterChange = new ArrayList<Range>();
    List<Range> changedRanges = new ArrayList<Range>();

    sortRanges(beforeChangedLine1, beforeChangedLine2, linesShift, rangesBeforeChange, changedRanges, rangesAfterChange);

    Range firstChangedRange = ContainerUtil.getFirstItem(changedRanges);
    Range lastChangedRange = ContainerUtil.getLastItem(changedRanges);

    if (firstChangedRange != null && firstChangedRange.getLine1() < beforeChangedLine1) {
      beforeChangedLine1 = firstChangedRange.getLine1();
    }
    if (lastChangedRange != null && lastChangedRange.getLine2() > beforeChangedLine2) {
      beforeChangedLine2 = lastChangedRange.getLine2();
    }

    doUpdateRanges(beforeChangedLine1, beforeChangedLine2, linesShift, beforeTotalLines,
                   rangesBeforeChange, changedRanges, rangesAfterChange);
  }

  private void doUpdateRanges(int beforeChangedLine1,
                              int beforeChangedLine2,
                              int linesShift, // before -> after
                              int beforeTotalLines,
                              @NotNull List<Range> rangesBefore,
                              @NotNull List<Range> changedRanges,
                              @NotNull List<Range> rangesAfter) {
    try {
      int vcsTotalLines = getLineCount(myVcsDocument);

      Range lastRangeBefore = ContainerUtil.getLastItem(rangesBefore);
      Range firstRangeAfter = ContainerUtil.getFirstItem(rangesAfter);

      int afterChangedLine1 = beforeChangedLine1;
      int afterChangedLine2 = beforeChangedLine2 + linesShift;

      int vcsLine1 = getVcsLine1(lastRangeBefore, beforeChangedLine1);
      int vcsLine2 = getVcsLine2(firstRangeAfter, beforeChangedLine2, beforeTotalLines, vcsTotalLines);

      List<Range> newChangedRanges = getNewChangedRanges(afterChangedLine1, afterChangedLine2, vcsLine1, vcsLine2);

      shiftRanges(rangesAfter, linesShift);

      if (!changedRanges.equals(newChangedRanges)) {
        replaceRanges(changedRanges, newChangedRanges);

        myRanges = new ArrayList<Range>(rangesBefore.size() + newChangedRanges.size() + rangesAfter.size());

        myRanges.addAll(rangesBefore);
        myRanges.addAll(newChangedRanges);
        myRanges.addAll(rangesAfter);

        for (Range range : myRanges) {
          if (!range.hasHighlighter()) range.setHighlighter(createHighlighter(range));
        }

        if (myRanges.isEmpty() && myVirtualFile != null) {
          SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
              FileDocumentManager.getInstance().saveDocument(myDocument);
              boolean stillEmpty;
              synchronized (myLock) {
                stillEmpty = myRanges.isEmpty();
              }
              if (stillEmpty) {
                // file was modified, and now it's not -> dirty local change
                myVcsDirtyScopeManager.fileDirty(myVirtualFile);
              }
            }
          });
        }
      }
    }
    catch (ProcessCanceledException ignore) {
    }
    catch (FilesTooBigForDiffException e1) {
      installAnathema();
      removeHighlightersFromMarkupModel();
    }
  }

  private static int getVcsLine1(@Nullable Range range, int line) {
    return range == null ? line : line + range.getVcsLine2() - range.getLine2();
  }

  private static int getVcsLine2(@Nullable Range range, int line, int totalLinesBefore, int totalLinesAfter) {
    return range == null ? totalLinesAfter - totalLinesBefore + line : line + range.getVcsLine1() - range.getLine1();
  }

  private List<Range> getNewChangedRanges(int changedLine1, int changedLine2, int vcsLine1, int vcsLine2)
    throws FilesTooBigForDiffException {

    if (changedLine1 == changedLine2 && vcsLine1 == vcsLine2) {
      return Collections.emptyList();
    }
    if (changedLine1 == changedLine2) {
      return Collections.singletonList(new Range(changedLine1, changedLine2, vcsLine1, vcsLine2, Range.DELETED));
    }
    if (vcsLine1 == vcsLine2) {
      return Collections.singletonList(new Range(changedLine1, changedLine2, vcsLine1, vcsLine2, Range.INSERTED));
    }

    List<String> lines = new DocumentWrapper(myDocument).getLines(changedLine1, changedLine2 - 1);
    List<String> vcsLines = new DocumentWrapper(myVcsDocument).getLines(vcsLine1, vcsLine2 - 1);

    return new RangesBuilder(lines, vcsLines, changedLine1, vcsLine1).getRanges();
  }

  private void replaceRanges(@NotNull List<Range> rangesInChange, @NotNull List<Range> newRangesInChange) {
    for (Range range : rangesInChange) {
      if (range.getHighlighter() != null) {
        range.getHighlighter().dispose();
      }
      range.setHighlighter(null);
      range.invalidate();
    }
    for (Range range : newRangesInChange) {
      range.setHighlighter(createHighlighter(range));
    }
  }

  private static void shiftRanges(@NotNull List<Range> rangesAfterChange, int shift) {
    for (final Range range : rangesAfterChange) {
      range.shift(shift);
    }
  }

  private void sortRanges(int beforeChangedLine1,
                          int beforeChangedLine2,
                          int linesShift,
                          @NotNull List<Range> rangesBeforeChange,
                          @NotNull List<Range> changedRanges,
                          @NotNull List<Range> rangesAfterChange) {
    if (!Registry.is("diff.status.tracker.skip.spaces")) {
      for (Range range : myRanges) {
        if (range.getLine2() < beforeChangedLine1) {
          rangesBeforeChange.add(range);
        }
        else if (range.getLine1() > beforeChangedLine2) {
          rangesAfterChange.add(range);
        }
        else {
          changedRanges.add(range);
        }
      }
    }
    else {
      int lastBefore = -1;
      int firstAfter = myRanges.size();
      for (int i = 0; i < myRanges.size(); i++) {
        Range range = myRanges.get(i);

        if (range.getLine2() < beforeChangedLine1) {
          lastBefore = i;
        }
        else if (range.getLine1() > beforeChangedLine2) {
          firstAfter = i;
          break;
        }
      }


      // Expand on ranges, that are separated from changes only by empty/whitespaces lines
      // This is needed to reduce amount of confusing cases, when changed blocks are matched wrong due to matched empty lines between them
      CharSequence sequence = myDocument.getCharsSequence();

      while (true) {
        if (lastBefore == -1) break;

        if (lastBefore < myRanges.size() - 1 && firstAfter - lastBefore > 1) {
          Range firstChangedRange = myRanges.get(lastBefore + 1);
          if (firstChangedRange.getLine1() < beforeChangedLine1) {
            beforeChangedLine1 = firstChangedRange.getLine1();
          }
        }

        if (beforeChangedLine1 >= getLineCount(myDocument)) break;
        int offset1 = myDocument.getLineStartOffset(beforeChangedLine1) - 2;

        int deltaLines = 0;
        while (offset1 > 0) {
          char c = sequence.charAt(offset1);
          if (!StringUtil.isWhiteSpace(c)) break;
          if (c == '\n') deltaLines++;
          offset1--;
        }

        if (deltaLines == 0) break;
        beforeChangedLine1 -= deltaLines;

        if (myRanges.get(lastBefore).getLine2() < beforeChangedLine1) break;
        while (lastBefore != -1 && myRanges.get(lastBefore).getLine2() >= beforeChangedLine1) {
          lastBefore--;
        }
      }

      while (true) {
        if (firstAfter == myRanges.size()) break;

        if (firstAfter > 0 && firstAfter - lastBefore > 1) {
          Range lastChangedRange = myRanges.get(firstAfter - 1);
          if (lastChangedRange.getLine2() > beforeChangedLine2) {
            beforeChangedLine2 = lastChangedRange.getLine2();
          }
        }

        if (beforeChangedLine2 + linesShift < 1) break;
        int offset2 = myDocument.getLineEndOffset(beforeChangedLine2 + linesShift - 1) + 1;

        int deltaLines = 0;
        while (offset2 < sequence.length()) {
          char c = sequence.charAt(offset2);
          if (!StringUtil.isWhiteSpace(c)) break;
          if (c == '\n') deltaLines++;
          offset2++;
        }

        if (deltaLines == 0) break;
        beforeChangedLine2 += deltaLines;

        if (myRanges.get(firstAfter).getLine1() > beforeChangedLine2) break;
        while (firstAfter != myRanges.size() && myRanges.get(firstAfter).getLine1() <= beforeChangedLine2) {
          firstAfter++;
        }
      }


      for (int i = 0; i < myRanges.size(); i++) {
        Range range = myRanges.get(i);
        if (i <= lastBefore) {
          rangesBeforeChange.add(range);
        }
        else if (i >= firstAfter) {
          rangesAfterChange.add(range);
        }
        else {
          changedRanges.add(range);
        }
      }
    }
  }

  @Nullable
  Range getNextRange(final Range range) {
    synchronized (myLock) {
      final int index = myRanges.indexOf(range);
      if (index == myRanges.size() - 1) return null;
      return myRanges.get(index + 1);
    }
  }

  @Nullable
  Range getPrevRange(final Range range) {
    synchronized (myLock) {
      final int index = myRanges.indexOf(range);
      if (index <= 0) return null;
      return myRanges.get(index - 1);
    }
  }

  @Nullable
  public Range getNextRange(final int line) {
    synchronized (myLock) {
      final Range currentRange = getRangeForLine(line);
      if (currentRange != null) {
        return getNextRange(currentRange);
      }

      for (final Range range : myRanges) {
        if (line > range.getLine1() || line > range.getLine2()) {
          continue;
        }
        return range;
      }
      return null;
    }
  }

  @Nullable
  public Range getPrevRange(final int line) {
    synchronized (myLock) {
      final Range currentRange = getRangeForLine(line);
      if (currentRange != null) {
        return getPrevRange(currentRange);
      }

      for (ListIterator<Range> iterator = myRanges.listIterator(myRanges.size()); iterator.hasPrevious(); ) {
        final Range range = iterator.previous();
        if (range.getLine1() > line) {
          continue;
        }
        return range;
      }
      return null;
    }
  }

  @Nullable
  public Range getRangeForLine(final int line) {
    synchronized (myLock) {
      for (final Range range : myRanges) {
        if (range.getType() == Range.DELETED && line == range.getLine1()) {
          return range;
        }
        else if (line >= range.getLine1() && line < range.getLine2()) {
          return range;
        }
      }
      return null;
    }
  }

  private void doRollbackRange(@NotNull Range range) {
    if (range.getType() == Range.MODIFIED) {
      TextRange currentTextRange = getCurrentTextRange(range);
      int offset1 = currentTextRange.getStartOffset();
      int offset2 = currentTextRange.getEndOffset();

      CharSequence vcsContent = getVcsContent(range);
      myDocument.replaceString(offset1, offset2, vcsContent);
    }
    else if (range.getType() == Range.INSERTED) {
      TextRange currentTextRange = getCurrentTextRange(range);
      int offset1 = currentTextRange.getStartOffset();
      int offset2 = currentTextRange.getEndOffset();

      if (offset1 > 0) {
        offset1--;
      }
      else if (offset2 < myDocument.getTextLength()) {
        offset2++;
      }
      myDocument.deleteString(offset1, offset2);
    }
    else if (range.getType() == Range.DELETED) {
      CharSequence content = getVcsContent(range);
      if (range.getLine2() == getLineCount(myDocument)) {
        myDocument.insertString(myDocument.getTextLength(), "\n" + content);
      }
      else {
        myDocument.insertString(myDocument.getLineStartOffset(range.getLine2()), content + "\n");
      }
    }
    else {
      throw new IllegalArgumentException("Unknown range type: " + range.getType());
    }
  }

  public void rollbackChanges(@NotNull Range range) {
    myApplication.assertWriteAccessAllowed();

    synchronized (myLock) {
      if (myBulkUpdate) return;

      if (!range.isValid()) {
        LOG.warn("Rollback of invalid range");
        return;
      }

      doRollbackRange(range);
    }
  }

  public void rollbackChanges(@NotNull BitSet lines) {
    myApplication.assertWriteAccessAllowed();

    synchronized (myLock) {
      if (myBulkUpdate) return;

      try {
        mySuppressUpdate = true;

        Range first = null;
        Range last = null;

        int shift = 0;
        for (Range range : myRanges) {
          if (!range.isValid()) {
            LOG.warn("Rollback of invalid range");
            break;
          }

          boolean check;
          if (range.getLine1() == range.getLine2()) {
            check = lines.get(range.getLine1());
          }
          else {
            int next = lines.nextSetBit(range.getLine1());
            check = next != -1 && next < range.getLine2();
          }

          if (check) {
            if (first == null) {
              first = range;
            }
            last = range;

            Range shiftedRange = new Range(range);
            shiftedRange.shift(shift);

            doRollbackRange(shiftedRange);

            shift += (range.getVcsLine2() - range.getVcsLine1()) - (range.getLine2() - range.getLine1());
          }
        }

        if (first != null) {
          int beforeChangedLine1 = first.getLine1();
          int beforeChangedLine2 = last.getLine2();

          int beforeTotalLines = getLineCount(myDocument) - shift;

          doUpdateRanges(beforeChangedLine1, beforeChangedLine2, shift, beforeTotalLines);
        }
      }
      catch (Throwable e) {
        reinstallRanges();
        if (e instanceof Error) throw ((Error)e);
        if (e instanceof RuntimeException) throw ((RuntimeException)e);
        throw new RuntimeException(e);
      }
      finally {
        mySuppressUpdate = false;
      }
    }
  }

  public CharSequence getVcsContent(@NotNull Range range) {
    synchronized (myLock) {
      TextRange textRange = getVcsRange(range);
      final int startOffset = textRange.getStartOffset();
      final int endOffset = textRange.getEndOffset();
      return myVcsDocument.getCharsSequence().subSequence(startOffset, endOffset);
    }
  }

  @NotNull
  TextRange getCurrentTextRange(@NotNull Range range) {
    synchronized (myLock) {
      if (!range.isValid()) {
        LOG.warn("Current TextRange of invalid range");
      }

      return getRange(range.getLine1(), range.getLine2(), myDocument);
    }
  }

  @NotNull
  TextRange getVcsRange(@NotNull Range range) {
    synchronized (myLock) {
      if (!range.isValid()) {
        LOG.warn("Vcs TextRange of invalid range");
      }

      return getRange(range.getVcsLine1(), range.getVcsLine2(), myVcsDocument);
    }
  }

  /**
   * Return affected range, without non-internal '\n'
   * so if last line is not empty, the last symbol will be not '\n'
   * <p/>
   * So we consider '\n' not as a part of line, but a separator between lines
   */
  @NotNull
  private static TextRange getRange(int line1, int line2, @NotNull Document document) {
    if (line1 == line2) {
      int lineStartOffset = line1 < getLineCount(document) ? document.getLineStartOffset(line1) : document.getTextLength();
      return new TextRange(lineStartOffset, lineStartOffset);
    }
    else {
      int startOffset = document.getLineStartOffset(line1);
      int endOffset = document.getLineEndOffset(line2 - 1);
      return new TextRange(startOffset, endOffset);
    }
  }

  public static LineStatusTracker createOn(@Nullable VirtualFile virtualFile, @NotNull final Document doc, final Project project) {
    final Document document = new DocumentImpl("", true);
    return new LineStatusTracker(doc, document, project, virtualFile);
  }

  public void baseRevisionLoadFailed() {
    synchronized (myLock) {
      myBaseLoaded = BaseLoadState.FAILED;
    }
  }

  Project getProject() {
    return myProject;
  }

  public enum BaseLoadState {
    LOADING,
    FAILED,
    LOADED
  }

  public static class RevisionPack {
    private final long myNumber;
    private final VcsRevisionNumber myRevision;

    public RevisionPack(long number, VcsRevisionNumber revision) {
      myNumber = number;
      myRevision = revision;
    }

    public long getNumber() {
      return myNumber;
    }

    public VcsRevisionNumber getRevision() {
      return myRevision;
    }

    public boolean after(final RevisionPack previous) {
      if (myRevision.equals(previous.getRevision())) return false;
      return myNumber > previous.getNumber();
    }

    @Override
    public boolean equals(Object o) {
      if (this == o) return true;
      if (o == null || getClass() != o.getClass()) return false;

      RevisionPack that = (RevisionPack)o;

      return myRevision.equals(that.getRevision());
    }

    @Override
    public int hashCode() {
      return myRevision.hashCode();
    }
  }

  private void installAnathema() {
    myAnathemaThrown = true;
    final FileEditor[] editors = myFileEditorManager.getAllEditors(myVirtualFile);
    for (FileEditor editor : editors) {
      CanNotCalculateDiffPanel panel = editor.getUserData(PANEL_KEY);
      if (panel == null) {
        final CanNotCalculateDiffPanel newPanel = new CanNotCalculateDiffPanel();
        editor.putUserData(PANEL_KEY, newPanel);
        myFileEditorManager.addTopComponent(editor, newPanel);
      }
    }
  }

  public static class CanNotCalculateDiffPanel extends EditorNotificationPanel {
    public CanNotCalculateDiffPanel() {
      myLabel.setText("Can not highlight changed lines. File is too big and there are too many changes.");
    }
  }

  private static int getLineCount(@NotNull Document document) {
    return Math.max(document.getLineCount(), 1);
  }
}