/*
  Copyright (c) 2023 Alex Diener
  
  This software is provided 'as-is', without any express or implied
  warranty. In no event will the authors be held liable for any damages
  arising from the use of this software.
  
  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:
  
  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.
  
  Alex Diener alex@ludobloom.com
*/

#include "utilities/UndoStack.h"

#define stemobject_implementation UndoStack

stemobject_vtable_begin();
stemobject_vtable_entry(dispose);
stemobject_vtable_end();

UndoStack * UndoStack_create(void * target) {
	stemobject_create_implementation(init, target)
}

bool UndoStack_init(UndoStack * self, void * target) {
	call_super(init, self);
	self->target = target;
	self->nodeCount = 0;
	self->nodeAllocatedCount = 0;
	self->nodes = NULL;
	self->nextNodeID = 1;
	self->currentDepth = 0;
	return true;
}

void UndoStack_dispose(UndoStack * self) {
	for (unsigned int nodeIndex = 0; nodeIndex < self->nodeCount; nodeIndex++) {
		call_virtual(dispose, self->nodes[nodeIndex].stateDelta);
	}
	free(self->nodes);
	call_super_virtual(dispose, self);
}

UndoStack * UndoStack_copy(UndoStack * self) {
	UndoStack * copy = UndoStack_create(self->target);
	copy->nodeCount = self->nodeCount;
	copy->nodeAllocatedCount = copy->nodeCount;
	copy->nodes = malloc(copy->nodeCount * sizeof(*copy->nodes));
	for (unsigned int nodeIndex = 0; nodeIndex < copy->nodeCount; nodeIndex++) {
		copy->nodes[nodeIndex] = self->nodes[nodeIndex];
		copy->nodes[nodeIndex].stateDelta = call_virtual(copy, self->nodes[nodeIndex].stateDelta);
	}
	copy->nextNodeID = self->nextNodeID;
	copy->currentDepth = self->currentDepth;
	return copy;
}

void UndoStack_appendNode(UndoStack * self, compat_type(UndoStateDelta *) stateDelta) {
	for (unsigned int nodeIndex = self->currentDepth; nodeIndex < self->nodeCount; nodeIndex++) {
		call_virtual(dispose, self->nodes[nodeIndex].stateDelta);
	}
	self->nodeCount = self->currentDepth;
	if (self->nodeCount >= self->nodeAllocatedCount) {
		self->nodeAllocatedCount = self->nodeAllocatedCount * 2 + (self->nodeAllocatedCount == 0) * 32;
		self->nodes = realloc(self->nodes, self->nodeAllocatedCount * sizeof(*self->nodes));
	}
	self->nodes[self->nodeCount].uniqueID = self->nextNodeID++;
	self->nodes[self->nodeCount].stateDelta = stateDelta;
	self->currentDepth++;
	self->nodeCount++;
}

bool UndoStack_canUndo(UndoStack * self) {
	return self->currentDepth > 0;
}

bool UndoStack_canRedo(UndoStack * self) {
	return self->currentDepth < self->nodeCount;
}

UndoStateDelta * UndoStack_getStateDeltaForUndo(UndoStack * self) {
	if (self->currentDepth == 0) {
		return NULL;
	}
	return self->nodes[self->currentDepth - 1].stateDelta;
}

UndoStateDelta * UndoStack_getStateDeltaForRedo(UndoStack * self) {
	if (self->currentDepth >= self->nodeCount) {
		return NULL;
	}
	return self->nodes[self->currentDepth].stateDelta;
}

bool UndoStack_undo(UndoStack * self) {
	if (self->currentDepth == 0) {
		return false;
	}
	call_virtual(revert, self->nodes[self->currentDepth - 1].stateDelta, self->target);
	self->currentDepth--;
	return true;
}

bool UndoStack_redo(UndoStack * self) {
	if (self->currentDepth >= self->nodeCount) {
		return false;
	}
	call_virtual(apply, self->nodes[self->currentDepth].stateDelta, self->target);
	self->currentDepth++;
	return true;
}

unsigned int UndoStack_getCurrentNodeID(UndoStack * self) {
	if (self->currentDepth == 0 || self->currentDepth > self->nodeCount) {
		return 0;
	}
	return self->nodes[self->currentDepth - 1].uniqueID;
}

void UndoStack_removeAllNodes(UndoStack * self) {
	for (unsigned int nodeIndex = 0; nodeIndex < self->nodeCount; nodeIndex++) {
		call_virtual(dispose, self->nodes[nodeIndex].stateDelta);
	}
	self->nodeCount = 0;
	self->currentDepth = 0;
}