#include <Xmd/Buffer.h>
#include <string.h>
#include <stdio.h>

#define XmdBUFFER_GROWTH_FACTOR    2
#define XmdBUFFER_INITIAL_CAPACITY 8

struct _XmdBuffer {
	void *   data;
	Cardinal size;
	Cardinal length;
	Cardinal capacity;
};

static void  XmdBufferResize (XmdBuffer *buffer, Cardinal length);
static void  XmdBufferFit    (XmdBuffer *buffer);
static void *XmdBufferOffset (XmdBuffer *buffer, Cardinal index);

XmdBuffer *_XmdBufferNew (Cardinal size) {
	XmdBuffer *buffer = XtNew(XmdBuffer);
	if (buffer == NULL) return NULL;
	
	buffer->size     = size;
	buffer->length   = 0;
	buffer->capacity = XmdBUFFER_INITIAL_CAPACITY;
	buffer->data     = XtCalloc(buffer->capacity, buffer->size);
	if (buffer->data == NULL) {
		XmdBufferFree(buffer);
		return NULL;
	}
	
	XmdBufferFit(buffer);
	return buffer;
}

void XmdBufferResize (XmdBuffer *buffer, Cardinal length) {
	buffer->length = length;
	XmdBufferFit(buffer);
}

void XmdBufferFit (XmdBuffer *buffer) {
	if (buffer->length > buffer->capacity) {
		buffer->capacity *= XmdBUFFER_GROWTH_FACTOR;
		buffer->data = XtReallocArray (
			buffer->data,
			buffer->capacity,
			buffer->size);
	}
}

void *XmdBufferOffset (XmdBuffer *buffer, Cardinal index) {
	return buffer->data + (index * buffer->size);
}

void XmdBufferPush (XmdBuffer *buffer, void *element) {
	Cardinal index = buffer->length;
	XmdBufferResize(buffer, buffer->length + 1);
	XmdBufferPoke(buffer, index, element);
}

void XmdBufferPop (XmdBuffer *buffer, void *element) {
	Cardinal index = buffer->length - 1;
	XmdBufferPeek(buffer, index, element);
	XmdBufferResize(buffer, index);
}

void XmdBufferPoke (XmdBuffer *buffer, Cardinal index, void *element) {
	if (index > buffer->length) return;
	memcpy (
		XmdBufferOffset(buffer, index),
		element,
		buffer->size);
	
	char test;
	XmdBufferPeek(buffer, index, &test);
}

void XmdBufferPeek (XmdBuffer *buffer, Cardinal index, void *element) {
	if (index > buffer->length) return;
	memcpy (
		element,
		XmdBufferOffset(buffer, index),
		buffer->size);
}

void *XmdBufferBreak (XmdBuffer *buffer) {
	void *data = buffer->data;
	XtFree((char *)(buffer));
	return data;
}

void XmdBufferFree (XmdBuffer *buffer) {
	if (buffer->data != NULL) {
		XtFree(buffer->data);
	}
	XtFree((char *)(buffer));
}