/* This file is part of
 * ====================================================== 
 * 
 *           LyX, The Document Processor
 *        
 *           Copyright 1995-2001 The LyX Team.
 *
 * ====================================================== */

#include <config.h>

#ifdef __GNUG__
#pragma implementation
#endif

#include "undo_funcs.h"
#include "lyxtext.h"
#include "BufferView.h"
#include "buffer.h"
#include "insets/inset.h"
#include "debug.h"
#include "support/LAssert.h"

/// the flag used by FinishUndo();
bool undo_finished;
/// a flag
bool undo_frozen;


bool textUndo(BufferView * bv)
{
	// returns false if no undo possible
	Undo * undo = bv->buffer()->undostack.top();
	bv->buffer()->undostack.pop();
	if (undo) {
		finishUndo();
		if (!undo_frozen) {
			Paragraph * first = bv->buffer()->getParFromID(undo->number_of_before_par);
			if (!first)
				first = firstUndoParagraph(bv, undo->number_of_inset_id);
			if (first) {
				bv->buffer()->redostack.push(
					createUndo(bv, undo->kind, first,
						   bv->buffer()->getParFromID(undo->number_of_behind_par)));
			}
		}
	}
	return textHandleUndo(bv, undo);
}


bool textRedo(BufferView * bv)
{
	// returns false if no redo possible
	Undo * undo = bv->buffer()->redostack.top();
	bv->buffer()->redostack.pop();
	if (undo) {
		finishUndo();
		if (!undo_frozen) {
			Paragraph * first = bv->buffer()->getParFromID(undo->number_of_before_par);
			if (!first)
				first = firstUndoParagraph(bv, undo->number_of_inset_id);
			if (first) {
				bv->buffer()->undostack.push(
					createUndo(bv, undo->kind, first,
					           bv->buffer()->getParFromID(undo->number_of_behind_par)));
			}
		}
	}
	return textHandleUndo(bv, undo);
}


bool textHandleUndo(BufferView * bv, Undo * undo)
{
	// returns false if no undo possible
	bool result = false;
	if (undo) {
		Paragraph * before =
			bv->buffer()->getParFromID(undo->number_of_before_par); 
		Paragraph * behind =
			bv->buffer()->getParFromID(undo->number_of_behind_par); 
		Paragraph * tmppar;
		Paragraph * tmppar2;
		Paragraph * endpar;
		Paragraph * tmppar5;

		// if there's no before take the beginning
		// of the document for redoing
		if (!before) {
			LyXText * t = bv->text;
			int num = undo->number_of_inset_id;
			if (undo->number_of_inset_id >= 0) {
				Inset * in = bv->buffer()->getInsetFromID(num);
				if (in) {
					t = in->getLyXText(bv);
				} else {
					num = -1;
				}
			}
			t->setCursorIntern(bv, firstUndoParagraph(bv, num), 0);
		}

		// replace the paragraphs with the undo informations

		Paragraph * tmppar3 = undo->par;
		undo->par = 0; 	// otherwise the undo destructor would
				// delete the paragraph 

		// get last undo par
		Paragraph * tmppar4 = tmppar3;
		if (tmppar4) {
			while (tmppar4->next())
				tmppar4 = tmppar4->next();
		} 
    
		// now remove the old text if there is any
		if (before != behind || (!behind && !before)) {
			if (before)
				tmppar5 = before->next();
			else
				tmppar5 = firstUndoParagraph(bv, undo->number_of_inset_id);
			tmppar2 = tmppar3;
			while (tmppar5 && tmppar5 != behind) {
				tmppar = tmppar5;
				tmppar5 = tmppar5->next();
				// a memory optimization for edit:
				// Only layout information 
				// is stored in the undo. So restore
				// the text informations. 
				if (undo->kind == Undo::EDIT) {
					tmppar2->setContentsFromPar(tmppar);
					tmppar->clearContents();
					tmppar2 = tmppar2->next();
				}
			}
		}
    
		// put the new stuff in the list if there is one
		if (tmppar3){
			if (before)
				before->next(tmppar3);
			else
				bv->text->ownerParagraph(tmppar3->id(),
							 tmppar3);

			tmppar3->previous(before);
		} else {
			// Do we really enter here ??? (Jug)
			if (!before)
				bv->text->ownerParagraph(behind);
		}
		if (tmppar4) {
			tmppar4->next(behind);
			if (behind)
				behind->previous(tmppar4);
		}
    
    
		// Set the cursor for redoing
		if (before) {
			bv->text->setCursorIntern(bv, before, 0);
		}

		// calculate the endpar for redoing the paragraphs.
		if (behind) {
				endpar = behind->next();
		} else
			endpar = behind;
    
		tmppar = bv->buffer()->getParFromID(undo->number_of_cursor_par);
		UpdatableInset* it = static_cast<UpdatableInset*>(tmppar3->inInset());
		if (it) {
			it->getLyXText(bv)->redoParagraphs(bv, it->getLyXText(bv)->cursor,
			                                   endpar);
			if (tmppar){
				it->getLyXText(bv)->setCursorIntern(bv, tmppar, undo->cursor_pos);
				it->getLyXText(bv)->updateCounters(bv, it->getLyXText(bv)->cursor.row());
			}
			LyXFont font;
			it->update(bv, font, false);
#ifdef THIS_DOES_NOT_WORK
			// we need this anyway as also if the undo was
			// inside an inset we have to redo the
			// paragraph breaking
			bv->text->redoParagraphs(bv, bv->text->cursor,
						 bv->text->cursor.par());
#endif
		} else {
			bv->text->redoParagraphs(bv, bv->text->cursor, endpar);
			if (tmppar) {
				bv->text->setCursorIntern(bv, tmppar, undo->cursor_pos);
				bv->text->updateCounters(bv, bv->text->cursor.row());
			}
		}
		result = true;
		delete undo;
	}
	finishUndo();
	bv->text->status(bv, LyXText::NEED_MORE_REFRESH);
	return result;
}


void finishUndo()
{
	// makes sure the next operation will be stored
	undo_finished = true;
}


void freezeUndo()
{
	// this is dangerous and for internal use only
	undo_frozen = true;
}


void unFreezeUndo()
{
	// this is dangerous and for internal use only
	undo_frozen = false;
}


void setUndo(BufferView * bv, Undo::undo_kind kind,
             Paragraph const * first, Paragraph const * behind)
{
	if (!undo_frozen)
		bv->buffer()->undostack.push(createUndo(bv, kind, first, behind));
	bv->buffer()->redostack.clear();
}


void setRedo(BufferView * bv, Undo::undo_kind kind,
             Paragraph const * first, Paragraph const * behind)
{
	bv->buffer()->redostack.push(createUndo(bv, kind, first, behind));
}


Undo * createUndo(BufferView * bv, Undo::undo_kind kind,
                  Paragraph const * first, Paragraph const * behind)
{
	lyx::Assert(first);

	int before_number = -1;
	int behind_number = -1;
	int inset_id = -1;

	if (first->previous())
		before_number = first->previous()->id();
	if (behind)
		behind_number = behind->id();
	if (first->inInset())
		inset_id = first->inInset()->id();

	// Undo::EDIT  and Undo::FINISH are
	// always finished. (no overlapping there)
	// overlapping only with insert and delete inside one paragraph: 
	// Nobody wants all removed  character
	// appear one by one when undoing. 
	// EDIT is special since only layout information, not the
	// contents of a paragaph are stored.
	if (!undo_finished && (kind != Undo::EDIT) && (kind != Undo::FINISH)){
		// check wether storing is needed
		if (!bv->buffer()->undostack.empty() && 
		    bv->buffer()->undostack.top()->kind == kind &&
		    bv->buffer()->undostack.top()->number_of_before_par == before_number &&
		    bv->buffer()->undostack.top()->number_of_behind_par == behind_number) {
			// no undo needed
			return 0;
		}
	}
	// create a new Undo
	Paragraph * undopar;

	Paragraph * start = const_cast<Paragraph *>(first);
	Paragraph * end = 0;

	if (behind)
		end = const_cast<Paragraph*>(behind->previous());
	else {
		end = start;
		while (end->next())
			end = end->next();
	}
	if (start && end && (start != end->next()) &&
	    ((before_number != behind_number) ||
		 ((before_number < 0) && (behind_number < 0)))) {
		Paragraph * tmppar = start;
		Paragraph * tmppar2 = new Paragraph(*tmppar, true);
		tmppar2->id(tmppar->id());
		
		// a memory optimization: Just store the layout information
		// when only edit
		if (kind == Undo::EDIT) {
			tmppar2->clearContents();
		}

		undopar = tmppar2;
  
		while (tmppar != end && tmppar->next()) {
			tmppar = tmppar->next();
			tmppar2->next(new Paragraph(*tmppar, false));
			tmppar2->next()->id(tmppar->id());
			// a memory optimization: Just store the layout
			// information when only edit
			if (kind == Undo::EDIT) {
				tmppar2->clearContents();
			}
			tmppar2->next()->previous(tmppar2);
			tmppar2 = tmppar2->next();
		}
		tmppar2->next(0);
	} else
		undopar = 0; // nothing to replace (undo of delete maybe)

	int cursor_par = undoCursor(bv).par()->id();
	int cursor_pos =  undoCursor(bv).pos();
	
	Undo * undo = new Undo(kind, inset_id,
	                       before_number, behind_number,  
	                       cursor_par, cursor_pos, undopar);
  
	undo_finished = false;
	return undo;
}


void setCursorParUndo(BufferView * bv)
{
	setUndo(bv, Undo::FINISH,
	        bv->text->cursor.par(),
			bv->text->cursor.par()->next());
}


Paragraph * firstUndoParagraph(BufferView * bv, int inset_id)
{
	Inset * inset = bv->buffer()->getInsetFromID(inset_id);
	if (inset) {
		Paragraph * result = inset->firstParagraph();
		if (result)
			return result;
	}
	return bv->text->ownerParagraph();
}


LyXCursor const & undoCursor(BufferView * bv)
{
	if (bv->theLockingInset())
		return bv->theLockingInset()->cursor(bv);
	return bv->text->cursor;
}