#include "history.h"

#include <stdlib.h>
#include <stddef.h>
#include <stdio.h>

History_t* History_init()
{
	History_t* history = malloc(sizeof(History_t));

	if (history != NULL) {
		history->FirstEl_p = NULL;
		history->LastEl_p = NULL;
		history->CurrEl_p = NULL;
		history->size = 0;
	}

	return history;
}


int History_deinit(History_t* history)
{
	// Check if the buffer there is something in the buffer
	if (history->FirstEl_p == NULL)
	{
		// Delete all elements in the buffer
		History_element_t* el = history->FirstEl_p;
		while (el != NULL)
		{
			History_element_t* nextEl = el->nextEl_p;
			free(el);
			el = nextEl;
		}
	}
	
	free(history);
	return 0;
}

int History_put(History_t *history, char* line)
{
	int retCode;
	if ((history->LastEl_p == NULL) && (history->FirstEl_p == NULL))
	{
		// buffer is empty. add first element
		history->FirstEl_p = malloc(sizeof(History_element_t));
		if (history->FirstEl_p != NULL)
		{
			history->FirstEl_p->line = line;
			history->FirstEl_p->prevEl_p = NULL;
			history->FirstEl_p->nextEl_p = NULL;

			history->LastEl_p = history->FirstEl_p;
			history->size = 1;
			retCode = 0;
		}
		else
		{ // failt to allocate memory
			retCode = -1;
		}
	}
	else if ((history->LastEl_p != NULL) && (history->FirstEl_p != NULL))
	{
		// add element to exsiting buffer
		History_element_t* el = malloc(sizeof(History_element_t));
		if (el != NULL)
		{
			el->line = line;
			el->prevEl_p = history->LastEl_p;
			el->nextEl_p = NULL;
			history->LastEl_p->nextEl_p = el;
			history->LastEl_p = el;
			history->size++;
			retCode = 0;
		}
		else
		{ // failt to allocate memory
			retCode = -2;
		}
	}
	else
	{
		retCode = -3;
	}

	if (retCode >= 0)
	{
		// reset current pointer
		history->CurrEl_p = NULL;
	}

	return retCode;
}

int History_getPrev(History_t* history, char** line)
{
	int retCode;
	if (history->CurrEl_p == NULL)
	{
		history->CurrEl_p = history->LastEl_p;
	}
	else
	{
		history->CurrEl_p = history->CurrEl_p->prevEl_p;
	}

	if (history->CurrEl_p != NULL)
	{
		*line = history->CurrEl_p->line;
		retCode = 0;
	}
	else
	{
		*line = NULL;
		retCode = -1;
	}
	return 0;
}

int History_getNext(History_t* history, char** line)
{
	int retCode;
	if (history->CurrEl_p != NULL)
	{
		history->CurrEl_p = history->CurrEl_p->nextEl_p;
	}

	if (history->CurrEl_p != NULL)
	{
		*line = history->CurrEl_p->line;
		retCode = 0;
	}
	else
	{
		*line = NULL;
		retCode = -1;
	}
	return 0;
}

unsigned int History_getSize(History_t *history)
{
	return history->size;
}