// Scintilla source code edit control
/** @file CellBuffer.cxx
 ** Manages a buffer of cells.
 **/
// Copyright 1998-2001 by Neil Hodgson <neilh@scintilla.org>
// The License.txt file describes the conditions under which this software may be distributed.

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdarg.h>

#include "Platform.h"

#include "Scintilla.h"
#include "SplitVector.h"
#include "Partitioning.h"
#include "CellBuffer.h"

#ifdef SCI_NAMESPACE
using namespace Scintilla;
#endif

LineVector::LineVector() : starts(256) {
   Init();
}

LineVector::~LineVector() {
   starts.DeleteAll();
}

void LineVector::Init() {
   starts.DeleteAll();
}

void LineVector::SetPerLine(PerLine *pl) {
   perLine = pl;
}

void LineVector::InsertText(int line, int delta) {
   starts.InsertText(line, delta);
}

void LineVector::InsertLine(int line, int position) {
   starts.InsertPartition(line, position);
   if (perLine) {
      perLine->InsertLine(line);
   }
}

void LineVector::SetLineStart(int line, int position) {
   starts.SetPartitionStartPosition(line, position);
}

void LineVector::RemoveLine(int line) {
   starts.RemovePartition(line);
   if (perLine) {
      perLine->RemoveLine(line);
   }
}

int LineVector::LineFromPosition(int pos) {
   return starts.PartitionFromPosition(pos);
}

Action::Action() {
   at = startAction;
   position = 0;
   data = 0;
   lenData = 0;
}

Action::~Action() {
   Destroy();
}

void Action::Create(actionType at_, int position_, char *data_, int lenData_, bool mayCoalesce_) {
   delete []data;
   position = position_;
   at = at_;
   data = data_;
   lenData = lenData_;
   mayCoalesce = mayCoalesce_;
}

void Action::Destroy() {
   delete []data;
   data = 0;
}

void Action::Grab(Action *source) {
   delete []data;

   position = source->position;
   at = source->at;
   data = source->data;
   lenData = source->lenData;
   mayCoalesce = source->mayCoalesce;

   // Ownership of source data transferred to this
   source->position = 0;
   source->at = startAction;
   source->data = 0;
   source->lenData = 0;
   source->mayCoalesce = true;
}

// The undo history stores a sequence of user operations that represent the user's view of the
// commands executed on the text.
// Each user operation contains a sequence of text insertion and text deletion actions.
// All the user operations are stored in a list of individual actions with 'start' actions used
// as delimiters between user operations.
// Initially there is one start action in the history.
// As each action is performed, it is recorded in the history. The action may either become
// part of the current user operation or may start a new user operation. If it is to be part of the
// current operation, then it overwrites the current last action. If it is to be part of a new
// operation, it is appended after the current last action.
// After writing the new action, a new start action is appended at the end of the history.
// The decision of whether to start a new user operation is based upon two factors. If a
// compound operation has been explicitly started by calling BeginUndoAction and no matching
// EndUndoAction (these calls nest) has been called, then the action is coalesced into the current
// operation. If there is no outstanding BeginUndoAction call then a new operation is started
// unless it looks as if the new action is caused by the user typing or deleting a stream of text.
// Sequences that look like typing or deletion are coalesced into a single user operation.

UndoHistory::UndoHistory() {

   lenActions = 100;
   actions = new Action[lenActions];
   maxAction = 0;
   currentAction = 0;
   undoSequenceDepth = 0;
   savePoint = 0;

   actions[currentAction].Create(startAction);
}

UndoHistory::~UndoHistory() {
   delete []actions;
   actions = 0;
}

void UndoHistory::EnsureUndoRoom() {
   // Have to test that there is room for 2 more actions in the array
   // as two actions may be created by the calling function
   if (currentAction >= (lenActions - 2)) {
      // Run out of undo nodes so extend the array
      int lenActionsNew = lenActions * 2;
      Action *actionsNew = new Action[lenActionsNew];
      if (!actionsNew)
         return;
      for (int act = 0; act <= currentAction; act++)
         actionsNew[act].Grab(&actions[act]);
      delete []actions;
      lenActions = lenActionsNew;
      actions = actionsNew;
   }
}

void UndoHistory::AppendAction(actionType at, int position, char *data, int lengthData,
   bool &startSequence, bool mayCoalesce) {
   EnsureUndoRoom();
   //Platform::DebugPrintf("%% %d action %d %d %d\n", at, position, lengthData, currentAction);
   //Platform::DebugPrintf("^ %d action %d %d\n", actions[currentAction - 1].at,
   //   actions[currentAction - 1].position, actions[currentAction - 1].lenData);
   if (currentAction < savePoint) {
      savePoint = -1;
   }
   int oldCurrentAction = currentAction;
   if (currentAction >= 1) {
      if (0 == undoSequenceDepth) {
         // Top level actions may not always be coalesced
         int targetAct = -1;
         const Action *actPrevious = &(actions[currentAction + targetAct]);
         // Container actions may forward the coalesce state of Scintilla Actions.
         while ((actPrevious->at == containerAction) && actPrevious->mayCoalesce) {
            targetAct--;
            actPrevious = &(actions[currentAction + targetAct]);
         }
         // See if current action can be coalesced into previous action
         // Will work if both are inserts or deletes and position is same
         if (currentAction == savePoint) {
            currentAction++;
         } else if (!actions[currentAction].mayCoalesce) {
            // Not allowed to coalesce if this set
            currentAction++;
         } else if (!mayCoalesce || !actPrevious->mayCoalesce) {
            currentAction++;
         } else if (at == containerAction || actions[currentAction].at == containerAction) {
            ;   // A coalescible containerAction
         } else if ((at != actPrevious->at) && (actPrevious->at != startAction)) {
            currentAction++;
         } else if ((at == insertAction) &&
                    (position != (actPrevious->position + actPrevious->lenData))) {
            // Insertions must be immediately after to coalesce
            currentAction++;
         } else if (at == removeAction) {
            if ((lengthData == 1) || (lengthData == 2)){
               if ((position + lengthData) == actPrevious->position) {
                  ; // Backspace -> OK
               } else if (position == actPrevious->position) {
                  ; // Delete -> OK
               } else {
                  // Removals must be at same position to coalesce
                  currentAction++;
               }
            } else {
               // Removals must be of one character to coalesce
               currentAction++;
            }
         } else {
            // Action coalesced.
         }

      } else {
         // Actions not at top level are always coalesced unless this is after return to top level
         if (!actions[currentAction].mayCoalesce)
            currentAction++;
      }
   } else {
      currentAction++;
   }
   startSequence = oldCurrentAction != currentAction;
   actions[currentAction].Create(at, position, data, lengthData, mayCoalesce);
   currentAction++;
   actions[currentAction].Create(startAction);
   maxAction = currentAction;
}

void UndoHistory::BeginUndoAction() {
   EnsureUndoRoom();
   if (undoSequenceDepth == 0) {
      if (actions[currentAction].at != startAction) {
         currentAction++;
         actions[currentAction].Create(startAction);
         maxAction = currentAction;
      }
      actions[currentAction].mayCoalesce = false;
   }
   undoSequenceDepth++;
}

void UndoHistory::EndUndoAction() {
   PLATFORM_ASSERT(undoSequenceDepth > 0);
   EnsureUndoRoom();
   undoSequenceDepth--;
   if (0 == undoSequenceDepth) {
      if (actions[currentAction].at != startAction) {
         currentAction++;
         actions[currentAction].Create(startAction);
         maxAction = currentAction;
      }
      actions[currentAction].mayCoalesce = false;
   }
}

void UndoHistory::DropUndoSequence() {
   undoSequenceDepth = 0;
}

void UndoHistory::DeleteUndoHistory() {
   for (int i = 1; i < maxAction; i++)
      actions[i].Destroy();
   maxAction = 0;
   currentAction = 0;
   actions[currentAction].Create(startAction);
   savePoint = 0;
}

void UndoHistory::SetSavePoint() {
   savePoint = currentAction;
}

bool UndoHistory::IsSavePoint() const {
   return savePoint == currentAction;
}

bool UndoHistory::CanUndo() const {
   return (currentAction > 0) && (maxAction > 0);
}

int UndoHistory::StartUndo() {
   // Drop any trailing startAction
   if (actions[currentAction].at == startAction && currentAction > 0)
      currentAction--;

   // Count the steps in this action
   int act = currentAction;
   while (actions[act].at != startAction && act > 0) {
      act--;
   }
   return currentAction - act;
}

const Action &UndoHistory::GetUndoStep() const {
   return actions[currentAction];
}

void UndoHistory::CompletedUndoStep() {
   currentAction--;
}

bool UndoHistory::CanRedo() const {
   return maxAction > currentAction;
}

int UndoHistory::StartRedo() {
   // Drop any leading startAction
   if (actions[currentAction].at == startAction && currentAction < maxAction)
      currentAction++;

   // Count the steps in this action
   int act = currentAction;
   while (actions[act].at != startAction && act < maxAction) {
      act++;
   }
   return act - currentAction;
}

const Action &UndoHistory::GetRedoStep() const {
   return actions[currentAction];
}

void UndoHistory::CompletedRedoStep() {
   currentAction++;
}

CellBuffer::CellBuffer() {
   readOnly = false;
   collectingUndo = true;
}

CellBuffer::~CellBuffer() {
}

char CellBuffer::CharAt(int position) const {
   return substance.ValueAt(position);
}

void CellBuffer::GetCharRange(char *buffer, int position, int lengthRetrieve) {
   if (lengthRetrieve < 0)
      return;
   if (position < 0)
      return;
   if ((position + lengthRetrieve) > substance.Length()) {
      Platform::DebugPrintf("Bad GetCharRange %d for %d of %d\n", position,
                            lengthRetrieve, substance.Length());
      return;
   }
   
   for (int i=0; i<lengthRetrieve; i++) {
      *buffer++ = substance.ValueAt(position + i);
   }
}

char CellBuffer::StyleAt(int position) {
   return style.ValueAt(position);
}

const char *CellBuffer::BufferPointer() { 
   return substance.BufferPointer();
}

// The char* returned is to an allocation owned by the undo history
const char *CellBuffer::InsertString(int position, const char *s, int insertLength, bool &startSequence) {
   char *data = 0;
   // InsertString and DeleteChars are the bottleneck though which all changes occur
   if (!readOnly) {
      if (collectingUndo) {
         // Save into the undo/redo stack, but only the characters - not the formatting
         // This takes up about half load time
         data = new char[insertLength];
         for (int i = 0; i < insertLength; i++) {
            data[i] = s[i];
         }
         uh.AppendAction(insertAction, position, data, insertLength, startSequence);
      }

      BasicInsertString(position, s, insertLength);
   }
   return data;
}

bool CellBuffer::SetStyleAt(int position, char styleValue, char mask) {
   styleValue &= mask;
   char curVal = style.ValueAt(position);
   if ((curVal & mask) != styleValue) {
      style.SetValueAt(position, static_cast<char>((curVal & ~mask) | styleValue));
      return true;
   } else {
      return false;
   }
}

bool CellBuffer::SetStyleFor(int position, int lengthStyle, char styleValue, char mask) {
   bool changed = false;
   PLATFORM_ASSERT(lengthStyle == 0 ||
      (lengthStyle > 0 && lengthStyle + position <= style.Length()));
   while (lengthStyle--) {
      char curVal = style.ValueAt(position);
      if ((curVal & mask) != styleValue) {
         style.SetValueAt(position, static_cast<char>((curVal & ~mask) | styleValue));
         changed = true;
      }
      position++;
   }
   return changed;
}

// The char* returned is to an allocation owned by the undo history
const char *CellBuffer::DeleteChars(int position, int deleteLength, bool &startSequence) {
   // InsertString and DeleteChars are the bottleneck though which all changes occur
   PLATFORM_ASSERT(deleteLength > 0);
   char *data = 0;
   if (!readOnly) {
      if (collectingUndo) {
         // Save into the undo/redo stack, but only the characters - not the formatting
         data = new char[deleteLength];
         for (int i = 0; i < deleteLength; i++) {
            data[i] = substance.ValueAt(position + i);
         }
         uh.AppendAction(removeAction, position, data, deleteLength, startSequence);
      }

      BasicDeleteChars(position, deleteLength);
   }
   return data;
}

int CellBuffer::Length() const {
   return substance.Length();
}

void CellBuffer::Allocate(int newSize) {
   substance.ReAllocate(newSize);
   style.ReAllocate(newSize);
}

void CellBuffer::SetPerLine(PerLine *pl) {
   lv.SetPerLine(pl);
}

int CellBuffer::Lines() const {
   return lv.Lines();
}

int CellBuffer::LineStart(int line) const {
   if (line < 0)
      return 0;
   else if (line >= Lines())
      return Length();
   else
      return lv.LineStart(line);
}

bool CellBuffer::IsReadOnly() {
   return readOnly;
}

void CellBuffer::SetReadOnly(bool set) {
   readOnly = set;
}

void CellBuffer::SetSavePoint() {
   uh.SetSavePoint();
}

bool CellBuffer::IsSavePoint() {
   return uh.IsSavePoint();
}

// Without undo

void CellBuffer::InsertLine(int line, int position) {
   lv.InsertLine(line, position);
}

void CellBuffer::RemoveLine(int line) {
   lv.RemoveLine(line);
}

void CellBuffer::BasicInsertString(int position, const char *s, int insertLength) {
   if (insertLength == 0)
      return;
   PLATFORM_ASSERT(insertLength > 0);

   substance.InsertFromArray(position, s, 0, insertLength);
   style.InsertValue(position, insertLength, 0);

   int lineInsert = lv.LineFromPosition(position) + 1;
   // Point all the lines after the insertion point further along in the buffer
   lv.InsertText(lineInsert-1, insertLength);
   char chPrev = substance.ValueAt(position - 1);
   char chAfter = substance.ValueAt(position + insertLength);
   if (chPrev == '\r' && chAfter == '\n') {
      // Splitting up a crlf pair at position
      InsertLine(lineInsert, position);
      lineInsert++;
   }
   char ch = ' ';
   for (int i = 0; i < insertLength; i++) {
      ch = s[i];
      if (ch == '\r') {
         InsertLine(lineInsert, (position + i) + 1);
         lineInsert++;
      } else if (ch == '\n') {
         if (chPrev == '\r') {
            // Patch up what was end of line
            lv.SetLineStart(lineInsert - 1, (position + i) + 1);
         } else {
            InsertLine(lineInsert, (position + i) + 1);
            lineInsert++;
         }
      }
      chPrev = ch;
   }
   // Joining two lines where last insertion is cr and following substance starts with lf
   if (chAfter == '\n') {
      if (ch == '\r') {
         // End of line already in buffer so drop the newly created one
         RemoveLine(lineInsert - 1);
      }
   }
}

void CellBuffer::BasicDeleteChars(int position, int deleteLength) {
   if (deleteLength == 0)
      return;

   if ((position == 0) && (deleteLength == substance.Length())) {
      // If whole buffer is being deleted, faster to reinitialise lines data
      // than to delete each line.
      lv.Init();
   } else {
      // Have to fix up line positions before doing deletion as looking at text in buffer
      // to work out which lines have been removed

      int lineRemove = lv.LineFromPosition(position) + 1;
      lv.InsertText(lineRemove-1, - (deleteLength));
      char chPrev = substance.ValueAt(position - 1);
      char chBefore = chPrev;
      char chNext = substance.ValueAt(position);
      bool ignoreNL = false;
      if (chPrev == '\r' && chNext == '\n') {
         // Move back one
         lv.SetLineStart(lineRemove, position);
         lineRemove++;
         ignoreNL = true;    // First \n is not real deletion
      }

      char ch = chNext;
      for (int i = 0; i < deleteLength; i++) {
         chNext = substance.ValueAt(position + i + 1);
         if (ch == '\r') {
            if (chNext != '\n') {
               RemoveLine(lineRemove);
            }
         } else if (ch == '\n') {
            if (ignoreNL) {
               ignoreNL = false;    // Further \n are real deletions
            } else {
               RemoveLine(lineRemove);
            }
         }

         ch = chNext;
      }
      // May have to fix up end if last deletion causes cr to be next to lf
      // or removes one of a crlf pair
      char chAfter = substance.ValueAt(position + deleteLength);
      if (chBefore == '\r' && chAfter == '\n') {
         // Using lineRemove-1 as cr ended line before start of deletion
         RemoveLine(lineRemove - 1);
         lv.SetLineStart(lineRemove - 1, position + 1);
      }
   }
   substance.DeleteRange(position, deleteLength);
   style.DeleteRange(position, deleteLength);
}

bool CellBuffer::SetUndoCollection(bool collectUndo) {
   collectingUndo = collectUndo;
   uh.DropUndoSequence();
   return collectingUndo;
}

bool CellBuffer::IsCollectingUndo() {
   return collectingUndo;
}

void CellBuffer::BeginUndoAction() {
   uh.BeginUndoAction();
}

void CellBuffer::EndUndoAction() {
   uh.EndUndoAction();
}

void CellBuffer::AddUndoAction(int token, bool mayCoalesce) {
   bool startSequence;
   uh.AppendAction(containerAction, token, 0, 0, startSequence, mayCoalesce);
}

void CellBuffer::DeleteUndoHistory() {
   uh.DeleteUndoHistory();
}

bool CellBuffer::CanUndo() {
   return uh.CanUndo();
}

int CellBuffer::StartUndo() {
   return uh.StartUndo();
}

const Action &CellBuffer::GetUndoStep() const {
   return uh.GetUndoStep();
}

void CellBuffer::PerformUndoStep() {
   const Action &actionStep = uh.GetUndoStep();
   if (actionStep.at == insertAction) {
      BasicDeleteChars(actionStep.position, actionStep.lenData);
   } else if (actionStep.at == removeAction) {
      BasicInsertString(actionStep.position, actionStep.data, actionStep.lenData);
   }
   uh.CompletedUndoStep();
}

bool CellBuffer::CanRedo() {
   return uh.CanRedo();
}

int CellBuffer::StartRedo() {
   return uh.StartRedo();
}

const Action &CellBuffer::GetRedoStep() const {
   return uh.GetRedoStep();
}

void CellBuffer::PerformRedoStep() {
   const Action &actionStep = uh.GetRedoStep();
   if (actionStep.at == insertAction) {
      BasicInsertString(actionStep.position, actionStep.data, actionStep.lenData);
   } else if (actionStep.at == removeAction) {
      BasicDeleteChars(actionStep.position, actionStep.lenData);
   }
   uh.CompletedRedoStep();
}

