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

#include <config.h>

#include "undo_funcs.h"
#include "lyxtext.h"
#include "funcrequest.h"
#include "BufferView.h"
#include "buffer.h"
#include "insets/updatableinset.h"
#include "insets/insettext.h"
#include "debug.h"
#include "support/LAssert.h"
#include "iterators.h"

#include <vector>

using std::vector;
using boost::shared_ptr;


/// The flag used by FinishUndo().
bool undo_finished;
/// Whether actions are not added to the undo stacks.
bool undo_frozen;

namespace {

/// Utility to return the cursor.
LyXCursor const & undoCursor(BufferView * bv)
{
	if (bv->theLockingInset())
		return bv->theLockingInset()->cursor(bv);
	return bv->text->cursor;
}


/**
 * Returns a pointer to the very first Paragraph depending of where
 * we are so it will return the first paragraph of the buffer or the
 * first paragraph of the textinset we're in.
 */
ParagraphList undoParagraphs(BufferView * bv, int inset_id)
{
	Inset * inset = bv->buffer()->getInsetFromID(inset_id);
	if (inset) {
		ParagraphList * result = inset->getParagraphs(0);
		if (result && !result->empty())
			return *result;
	}
	return bv->text->ownerParagraphs();
}


/**
 * Finish the undo operation in the case there was no entry
 * on the stack to perform.
 */
void finishNoUndo(BufferView * bv)
{
	freezeUndo();
	bv->unlockInset(bv->theLockingInset());
	finishUndo();
	bv->text->postPaint(0);
	unFreezeUndo();
}


// Returns false if no undo possible.
bool textHandleUndo(BufferView * bv, Undo & undo)
{
	Buffer * b = bv->buffer();

	ParIterator const before = b->getParFromID(undo.number_of_before_par);
	ParIterator const behind = b->getParFromID(undo.number_of_behind_par);
	ParIterator const end    = b->par_iterator_end();

	// If there's no before take the beginning
	// of the document for redoing.
	if (before == end) {
		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(undoParagraphs(bv, num).begin(), 0);
	}

	// Set the right(new) inset-owner of the paragraph if there is any.
	if (!undo.pars.empty()) {
		Inset * in = 0;
		if (before != end)
			in = before->inInset();
		else if (undo.number_of_inset_id >= 0)
			in = bv->buffer()->getInsetFromID(undo.number_of_inset_id);
		for (size_t i = 0, n = undo.pars.size(); i < n; ++i)
			undo.pars[i]->setInsetOwner(in);
	}

	// Replace the paragraphs with the undo informations.
	vector<Paragraph *> deletelist;

	// Now add old paragraphs to be deleted.
	if (before != behind || (behind == end && before == end)) {
		ParagraphList::iterator deletepar;
		if (before != end) {
			deletepar = *before;
			++deletepar;
		} else {
			deletepar = undoParagraphs(bv, undo.number_of_inset_id).begin();
		}
		// this surprisingly fills the undo! (Andre')
		size_t par = 0;
		//while (deletepar && deletepar != *behind)
		while (deletepar != *behind) {
			deletelist.push_back(&*deletepar);
			++deletepar;

			// A memory optimization for edit:
			// Only layout information
			// is stored in the undo. So restore
			// the text informations.
			if (undo.kind == Undo::EDIT) {
				undo.pars[par]->setContentsFromPar(*deletelist.back());
				++par;
			}
		}
	}

	// The order here is VERY IMPORTANT. We have to set the right
	// next/prev pointer in the paragraphs so that a rebuild of
	// the LyXText works!!!

	// Thread the end of the undo onto the par in front if any.
	if (!undo.pars.empty()) {
#warning FIXME
		//undo.pars.back()->next(&**behind);
		//if (behind != end)
		//(&**behind)->previous(undo.pars.back());
	}

	// Put the new stuff in the list if there is one.
	Paragraph * undopar = undo.pars.empty() ? 0 : undo.pars.front();
	if (!undo.pars.empty()) {
#warning FIXME
		//undo.pars.front()->previous(&**before);
		if (before != end) {
#warning FIXME
			//(&**before)->next(undopar);
		} else {
			int id = undoParagraphs(bv, undo.number_of_inset_id).front().id();
			ParIterator op = bv->buffer()->getParFromID(id);
			if (op != end && op->inInset()) {
#warning FIXME reimplementaion needed here
				//static_cast<InsetText*>(op->inInset())->paragraph(undopar);
			} else {
#warning FIXME reimplementation needed here
				//bv->buffer()->paragraphs.set(undopar);
			}
		}
	} else {
		// We enter here on DELETE undo operations where we
		// have to substitue the second paragraph with the
		// first if the removed one is the first.
		if (before == end && behind != end) {
			int id = undoParagraphs(bv, undo.number_of_inset_id).front().id();
			ParIterator op = bv->buffer()->getParFromID(id);
			if (op != end && op->inInset()) {
#warning FIXME reimplementation needed here
				//static_cast<InsetText*>(op->inInset())->paragraph(&**behind);
			} else {
#warning FIXME reimplementation needed here
				//bv->buffer()->paragraphs.set(&**behind);
			}
			undopar = &**behind;
		}
	}


	// Set the cursor for redoing.
	// If we have a par before the undopar.
	if (before != end) {
		Inset * it = before->inInset();
		if (it)
			it->getLyXText(bv)->setCursorIntern(*before, 0);
		else
			bv->text->setCursorIntern(*before, 0);
	}

// we are not ready for this we cannot set the cursor for a paragraph
// which is not already in a row of LyXText!!!
#if 0
	else { // otherwise this is the first one and we start here
		Inset * it = undopar->inInset();
		if (it)
			it->getLyXText(bv)->setCursorIntern(bv, undopar, 0);
		else
			bv->text->setCursorIntern(bv, undopar, 0);
	}
#endif

	UpdatableInset * it = 0;
	if (undopar)
		it = static_cast<UpdatableInset*>(undopar->inInset());

	LyXText * text = it ? it->getLyXText(bv) : bv->text;

	ParagraphList::iterator endpar = text->ownerParagraphs().end();

	// Calculate the endpar for redoing the paragraphs.
	if (behind != end) {
		endpar = *behind;
		++endpar;
	}

	text->redoParagraphs(text->cursor, endpar);
	ParIterator tmppar =
		bv->buffer()->getParFromID(undo.number_of_cursor_par);

	if (tmppar != end) {
		LyXText * t;
		Inset * it = tmppar->inInset();
		if (it) {
			FuncRequest cmd(bv, LFUN_INSET_EDIT, "left");
			it->localDispatch(cmd);
			t = it->getLyXText(bv);
		} else {
			t = bv->text;
		}
		t->setCursorIntern(*tmppar, undo.cursor_pos);
		// Clear any selection and set the selection
		// cursor for an evt. new selection.
		t->clearSelection();
		t->selection.cursor = t->cursor;
		t->updateCounters();
	}

	if (it) {
		bv->fitCursor();
		bv->updateInset(it);
		bv->text->setCursorIntern(bv->text->cursor.par(),
					  bv->text->cursor.pos());
	}

	// And here it's safe enough to delete all removed paragraphs.
	vector<Paragraph *>::iterator pit = deletelist.begin();
	for(; pit != deletelist.end(); ++pit) {
#warning FIXME
		//(*pit)->previous(0);
		//(*pit)->next(0);
		delete (*pit);
	}

	// Otherwise the undo destructor would delete the paragraphs
	undo.pars.resize(0);

	finishUndo();
	bv->text->postPaint(0);
	return true;
}


bool createUndo(BufferView * bv, Undo::undo_kind kind,
	ParagraphList::iterator itfirst, ParagraphList::iterator itbehind,
	shared_ptr<Undo> & u)
{
	Paragraph * const first = &*itfirst;
	Paragraph * const behind = &*itbehind;
	lyx::Assert(first);

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

#warning FIXME
	//if (first->previous())
	//	before_number = first->previous()->id();
	if (behind)
		behind_number = behind->id();
	if (first->inInset())
		inset_id = first->inInset()->id();

	Buffer * b = bv->buffer();

	// 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 whether storing is needed.
		if (!b->undostack.empty() &&
		    b->undostack.top()->kind == kind &&
		    b->undostack.top()->number_of_before_par == before_number &&
		    b->undostack.top()->number_of_behind_par == behind_number) {
			// No undo needed.
			return false;
		}
	}

	// Create a new Undo.
	std::vector<Paragraph *> undo_pars;

	Paragraph const * end = 0;

	if (behind) {
#warning FIXME
		//end = behind->previous();
	}else {
		end = first;
#warning FIXME
		//while (end->next())
		//	end = end->next();
	}

#warning FIXME
//	if (first && end && (first != end->next()) &&
//	    ((before_number != behind_number) ||
//		 ((before_number < 0) && (behind_number < 0))))
//	{
//		undo_pars.push_back(new Paragraph(*first, true));
//		for (Paragraph * tmppar = first; tmppar != end && tmppar->next(); ) {
//			tmppar = tmppar->next();
//			undo_pars.push_back(new Paragraph(*tmppar, true));
//			size_t const n = undo_pars.size();
//			undo_pars[n - 2]->next(undo_pars[n - 1]);
//			undo_pars[n - 1]->previous(undo_pars[n - 2]);
//		}
//		undo_pars.back()->next(0);
//	}

	// A memory optimization: Just store the layout
	// information when only edit.
	if (kind == Undo::EDIT) {
		for (size_t i = 0, n = undo_pars.size(); i < n; ++i)
			undo_pars[i]->clearContents();
	}

	int cursor_par = undoCursor(bv).par()->id();
	int cursor_pos = undoCursor(bv).pos();

	//lyxerr << "createUndo: inset_id: " << inset_id << "  before_number: "
	//	<< before_number << "  behind_number: " << behind_number << "\n";
	u.reset(new Undo(kind, inset_id,
		before_number, behind_number,
		cursor_par, cursor_pos, undo_pars));

	undo_finished = false;
	return true;
}


// Returns false if no undo possible.
bool textUndoOrRedo(BufferView * bv,
	limited_stack<boost::shared_ptr<Undo> > & stack,
		    limited_stack<boost::shared_ptr<Undo> > & /*otherstack*/)
{
	//Buffer * b = bv->buffer();

	if (stack.empty()) {
		finishNoUndo(bv);
		return false;
	}

	shared_ptr<Undo> undo = stack.top();
	stack.pop();
	finishUndo();

	if (!undo_frozen) {
/*
		ParIterator p = b->getParFromID(undo->number_of_before_par);
		bool ok = false;
		ParagraphList::iterator first;
		// default constructed?
		ParIterator const end = b->par_iterator_end();
		if (p != end) {
			first = p.par();
			if (first->next())
				first = first->next();
		} else
			first = undoParagraphs(bv, undo->number_of_inset_id).begin();
		if (first) {
			shared_ptr<Undo> u;
			ParIterator behind = b->getParFromID(undo->number_of_behind_par);
			if (createUndo(bv, undo->kind, first, behind.par(), u))
				otherstack.push(u);
		}
*/
	}

	// Now we can unlock the inset for saftey because the inset
	// pointer could be changed during the undo-function. Anyway
	// if needed we have to lock the right inset/position if this
	// is requested.
	freezeUndo();
	bv->unlockInset(bv->theLockingInset());
	bool const ret = textHandleUndo(bv, *undo.get());
	unFreezeUndo();
	return ret;
}

} // namespace anon


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;
}


bool textUndo(BufferView * bv)
{
	return textUndoOrRedo(bv, bv->buffer()->undostack,
			      bv->buffer()->redostack);
}


bool textRedo(BufferView * bv)
{
	return textUndoOrRedo(bv, bv->buffer()->redostack,
			      bv->buffer()->undostack);
}


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


void setRedo(BufferView * bv, Undo::undo_kind kind,
	     ParagraphList::iterator first, ParagraphList::iterator behind)
{
	shared_ptr<Undo> u;
	if (createUndo(bv, kind, first, behind, u))
		bv->buffer()->redostack.push(u);
}


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