/*
 * Copyright (C) 2007-2008 Tobias Brunner
 * Copyright (C) 2005-2006 Martin Willi
 * Copyright (C) 2005 Jan Hutter
 * Hochschule fuer Technik Rapperswil
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * for more details.
 */

#include <stdlib.h>

#include "linked_list.h"

typedef struct element_t element_t;

/**
 * This element holds a pointer to the value it represents.
 */
struct element_t {

	/**
	 * Value of a list item.
	 */
	void *value;

	/**
	 * Previous list element.
	 * 
	 * NULL if first element in list.
	 */
	element_t *previous;
	
	/**
	 * Next list element.
	 * 
	 * NULL if last element in list.
	 */
	element_t *next;
};

/**
 * Creates an empty linked list object.
 */
element_t *element_create(void *value)
{
	element_t *this = malloc_thing(element_t);
	
	this->previous = NULL;
	this->next = NULL;
	this->value = value;
	
	return (this);
}


typedef struct private_linked_list_t private_linked_list_t;

/**
 * Private data of a linked_list_t object.
 *
 */
struct private_linked_list_t {
	/**
	 * Public part of linked list.
	 */
	linked_list_t public;

	/**
	 * Number of items in the list.
	 */
	int count;

	/**
	 * First element in list.
	 * NULL if no elements in list.
	 */
	element_t *first;
	
	/**
	 * Last element in list.
	 * NULL if no elements in list.
	 */
	element_t *last;
};


typedef struct private_iterator_t private_iterator_t;

/**
 * Private variables and functions of linked list iterator.
 */
struct private_iterator_t {
	/**
	 * Public part of linked list iterator.
	 */
	iterator_t public;

	/**
	 * Associated linked list.
	 */
	private_linked_list_t * list;

	/**
	 * Current element of the iterator.
	 */
	element_t *current;

	/**
	 * Direction of iterator.
	 */
	bool forward;
};

typedef struct private_enumerator_t private_enumerator_t;

/**
 * linked lists enumerator implementation
 */
struct private_enumerator_t {

	/**
	 * implements enumerator interface
	 */
	enumerator_t enumerator;
	
	/**
	 * associated linked list
	 */
	private_linked_list_t *list;
	
	/**
	 * current item
	 */
	element_t *current;
};

/**
 * Implementation of private_enumerator_t.enumerator.enumerate.
 */
static bool enumerate(private_enumerator_t *this, void **item)
{
	if (!this->current)
	{
		if (!this->list->first)
		{
			return FALSE;
		}
		this->current = this->list->first;
	}
	else
	{
		if (!this->current->next)
		{
			return FALSE;
		}
		this->current = this->current->next;
	}
	*item = this->current->value;
	return TRUE;
}

/**
 * Implementation of linked_list_t.create_enumerator.
 */
static enumerator_t* create_enumerator(private_linked_list_t *this)
{
	private_enumerator_t *enumerator = malloc_thing(private_enumerator_t);
	
	enumerator->enumerator.enumerate = (void*)enumerate;
	enumerator->enumerator.destroy = (void*)free;
	enumerator->list = this;
	enumerator->current = NULL;
	
	return &enumerator->enumerator;
}

/**
 * Implementation of iterator_t.get_count.
 */
static int get_list_count(private_iterator_t *this)
{
	return this->list->count;
}

/**
 * Implementation of iterator_t.iterate.
 */
static bool iterate(private_iterator_t *this, void** value)
{
	if (this->forward)
	{
		this->current = this->current ? this->current->next : this->list->first;
	}
	else
	{
		this->current = this->current ? this->current->previous : this->list->last;
	}
	if (this->current == NULL)
	{
		return FALSE;
	}
	*value = this->current->value;
	return TRUE;
}

/**
 * Implementation of iterator_t.reset.
 */
static void iterator_reset(private_iterator_t *this)
{
	this->current = NULL;
}

/**
 * Implementation of iterator_t.remove.
 */
static status_t iterator_remove(private_iterator_t *this)
{
	element_t *new_current;

	if (this->current == NULL)
	{
		return NOT_FOUND;
	}

	if (this->list->count == 0)
	{
		return NOT_FOUND;
	}
	/* find out the new iterator position, depending on iterator direction */
	if (this->forward && this->current->previous != NULL)
	{
		new_current = this->current->previous;
	}
	else if (!this->forward && this->current->next != NULL)
	{
		new_current = this->current->next;
	}
	else
	{
		new_current = NULL;
	}

	/* now delete the entry :-) */
	if (this->current->previous == NULL)
	{
		if (this->current->next == NULL)
		{
			this->list->first = NULL;
			this->list->last = NULL;
		}
		else
		{
			this->current->next->previous = NULL;
			this->list->first = this->current->next;
		}
	}
	else if (this->current->next == NULL)
	{
		this->current->previous->next = NULL;
		this->list->last = this->current->previous;
	}
	else
	{
		this->current->previous->next = this->current->next;
		this->current->next->previous = this->current->previous;
	}
	
	this->list->count--;
	free(this->current);
	/* set the new iterator position */
	this->current = new_current;
	return SUCCESS;
}

/**
 * Implementation of iterator_t.insert_before.
 */
static void insert_before(private_iterator_t * iterator, void *item)
{
	if (iterator->current == NULL)
	{
		iterator->list->public.insert_first(&(iterator->list->public), item);
	}
	
	element_t *element = element_create(item);
	if (iterator->current->previous == NULL)
	{
		iterator->current->previous = element;
		element->next = iterator->current;
		iterator->list->first = element;
	}
	else
	{
		iterator->current->previous->next = element;
		element->previous = iterator->current->previous;
		iterator->current->previous = element;
		element->next = iterator->current;
	}
	iterator->list->count++;
}

/**
 * Implementation of iterator_t.replace.
 */
static status_t replace(private_iterator_t *this, void **old_item, void *new_item)
{
	if (this->current == NULL)
	{
		return NOT_FOUND;
	}
	if (old_item != NULL)
	{
		*old_item = this->current->value;
	}
	this->current->value = new_item;
	
	return SUCCESS;
}

/**
 * Implementation of iterator_t.insert_after.
 */
static void insert_after(private_iterator_t *iterator, void *item)
{
	if (iterator->current == NULL)
	{
		iterator->list->public.insert_first(&(iterator->list->public),item);
		return;
	}
	
	element_t *element = element_create(item);
	if (iterator->current->next == NULL)
	{
		iterator->current->next = element;
		element->previous = iterator->current;
		iterator->list->last = element;
	}
	else
	{
		iterator->current->next->previous = element;
		element->next = iterator->current->next;
		iterator->current->next = element;
		element->previous = iterator->current;
	}
	iterator->list->count++;
}

/**
 * Implementation of iterator_t.destroy.
 */
static void iterator_destroy(private_iterator_t *this)
{
	free(this);
}

/**
 * Implementation of linked_list_t.get_count.
 */
static int get_count(private_linked_list_t *this)
{
	return this->count;
}

/**
 * Implementation of linked_list_t.insert_first.
 */
static void insert_first(private_linked_list_t *this, void *item)
{
	element_t *element;
	
	element = element_create(item);
	if (this->count == 0)
	{
		/* first entry in list */
		this->first = element;
		this->last = element;
		element->previous = NULL;
		element->next = NULL;
	}
	else
	{
		element_t *old_first_element = this->first;
		element->next = old_first_element;
		element->previous = NULL;
		old_first_element->previous = element;
		this->first = element;
	}
	this->count++;
}

/**
 * unlink an element form the list, returns following element
 */
static element_t* remove_element(private_linked_list_t *this, element_t *element)
{
	element_t *next, *previous;

	next = element->next;
	previous = element->previous;
	free(element);
	if (next) 
	{
		next->previous = previous;
	}
	else
	{
		this->last = previous;
	}
	if (previous)
	{
		previous->next = next;
	}
	else
	{
		this->first = next;
	}
	if (--this->count == 0)
	{
		this->first = NULL;
		this->last = NULL;
	}
	return next;
}

/**
 * Implementation of linked_list_t.get_first.
 */
static status_t get_first(private_linked_list_t *this, void **item)
{
	if (this->count == 0)
	{
		return NOT_FOUND;
	}
	*item = this->first->value;
	return SUCCESS;
}

/**
 * Implementation of linked_list_t.remove_first.
 */
static status_t remove_first(private_linked_list_t *this, void **item)
{
	if (get_first(this, item) == SUCCESS)
	{
		remove_element(this, this->first);
		return SUCCESS;
	}
	return NOT_FOUND;
}

/**
 * Implementation of linked_list_t.insert_last.
 */
static void insert_last(private_linked_list_t *this, void *item)
{
	element_t *element = element_create(item);
	
	if (this->count == 0)
	{
		/* first entry in list */
		this->first = element;
		this->last = element;
		element->previous = NULL;
		element->next = NULL;
	}
	else
	{
		element_t *old_last_element = this->last;
		element->previous = old_last_element;
		element->next = NULL;
		old_last_element->next = element;
		this->last = element;
	}
	this->count++;
}

/**
 * Implementation of linked_list_t.get_last.
 */
static status_t get_last(private_linked_list_t *this, void **item)
{
	if (this->count == 0)
	{
		return NOT_FOUND;
	}
	*item = this->last->value;
	return SUCCESS;
}

/**
 * Implementation of linked_list_t.remove_last.
 */
static status_t remove_last(private_linked_list_t *this, void **item)
{
	if (get_last(this, item) == SUCCESS)
	{
		remove_element(this, this->last);
		return SUCCESS;
	}
	return NOT_FOUND;
}
	
/**
 * Implementation of linked_list_t.remove.
 */
static int remove_(private_linked_list_t *this, void *item,
				   bool (*compare)(void *,void*))
{
	element_t *current = this->first;
	int removed = 0;
	
	while (current)
	{
		if ((compare && compare(current->value, item)) ||
			(!compare && current->value == item))
		{
			removed++;
			current = remove_element(this, current);
		}
		else
		{
			current = current->next;
		}
	}
	return removed;
}

/**
 * Implementation of linked_list_t.remove_at.
 */
static void remove_at(private_linked_list_t *this, private_enumerator_t *enumerator)
{
	element_t *current;

	if (enumerator->current)
	{
		current = enumerator->current;
		enumerator->current = current->previous;
		remove_element(this, current);
	}
}

/**
 * Implementation of linked_list_t.find_first.
 */
static status_t find_first(private_linked_list_t *this, linked_list_match_t match,
		void **item, void *d1, void *d2, void *d3, void *d4, void *d5)
{
	element_t *current = this->first;
	
	while (current)
	{
		if ((match && match(current->value, d1, d2, d3, d4, d5)) ||
			(!match && item && current->value == *item))
		{
			if (item != NULL)
			{
				*item = current->value;
			}
			return SUCCESS;
		}
		current = current->next;
	}
	return NOT_FOUND;
}

/**
 * Implementation of linked_list_t.find_last.
 */
static status_t find_last(private_linked_list_t *this, linked_list_match_t match,
		void **item, void *d1, void *d2, void *d3, void *d4, void *d5)
{
	element_t *current = this->last;
	
	while (current)
	{
		if ((match && match(current->value, d1, d2, d3, d4, d5)) ||
			(!match && item && current->value == *item))
		{
			if (item != NULL)
			{
				*item = current->value;
			}
			return SUCCESS;
		}
		current = current->previous;
	}
	return NOT_FOUND;
}

/**
 * Implementation of linked_list_t.invoke_offset.
 */
static void invoke_offset(private_linked_list_t *this, size_t offset,
		void *d1, void *d2, void *d3, void *d4, void *d5)
{
	element_t *current = this->first;
	
	while (current)
	{
		linked_list_invoke_t *method = current->value + offset;
		(*method)(current->value, d1, d2, d3, d4, d5);
		current = current->next;
	}
}

/**
 * Implementation of linked_list_t.invoke_function.
 */
static void invoke_function(private_linked_list_t *this, linked_list_invoke_t fn,
		void *d1, void *d2, void *d3, void *d4, void *d5)
{
	element_t *current = this->first;
	
	while (current)
	{
		fn(current->value, d1, d2, d3, d4, d5);
		current = current->next;
	}
}

/**
 * Implementation of linked_list_t.clone_offset
 */
static linked_list_t *clone_offset(private_linked_list_t *this, size_t offset)
{
	linked_list_t *clone = linked_list_create();
	element_t *current = this->first;
	
	while (current)
	{
		void* (**method)(void*) = current->value + offset;
		clone->insert_last(clone, (*method)(current->value));
		current = current->next;
	}
	
	return clone;
}

/**
 * Implementation of linked_list_t.clone_function
 */
static linked_list_t *clone_function(private_linked_list_t *this, void* (*fn)(void*))
{
	linked_list_t *clone = linked_list_create();
	element_t *current = this->first;
	
	while (current)
	{
		clone->insert_last(clone, fn(current->value));
		current = current->next;
	}
	
	return clone;
}

/**
 * Implementation of linked_list_t.destroy.
 */
static void destroy(private_linked_list_t *this)
{
	void *value;
	/* Remove all list items before destroying list */
	while (remove_first(this, &value) == SUCCESS)
	{
		/* values are not destroyed so memory leaks are possible
		 * if list is not empty when deleting */
	}
	free(this);
}

/**
 * Implementation of linked_list_t.destroy_offset.
 */
static void destroy_offset(private_linked_list_t *this, size_t offset)
{
	element_t *current = this->first, *next;
	
	while (current)
	{
		void (**method)(void*) = current->value + offset;
		(*method)(current->value);
		next = current->next;
		free(current);
		current = next;
	}
	free(this);
}

/**
 * Implementation of linked_list_t.destroy_function.
 */
static void destroy_function(private_linked_list_t *this, void (*fn)(void*))
{
	element_t *current = this->first, *next;
	
	while (current)
	{
		fn(current->value);
		next = current->next;
		free(current);
		current = next;
	}
	free(this);
}

/**
 * Implementation of linked_list_t.create_iterator.
 */
static iterator_t *create_iterator(private_linked_list_t *linked_list, bool forward)
{
	private_iterator_t *this = malloc_thing(private_iterator_t);
	
	this->public.get_count = (int (*) (iterator_t*)) get_list_count;
	this->public.iterate = (bool (*) (iterator_t*, void **value)) iterate;
	this->public.insert_before = (void (*) (iterator_t*, void *item)) insert_before;
	this->public.insert_after = (void (*) (iterator_t*, void *item)) insert_after;
	this->public.replace = (status_t (*) (iterator_t*, void **, void *)) replace;
	this->public.remove = (status_t (*) (iterator_t*)) iterator_remove;
	this->public.reset = (void (*) (iterator_t*)) iterator_reset;
	this->public.destroy = (void (*) (iterator_t*)) iterator_destroy;
	
	this->forward = forward;
	this->current = NULL;
	this->list = linked_list;
	
	return &this->public;
}

/*
 * Described in header.
 */
linked_list_t *linked_list_create()
{
	private_linked_list_t *this = malloc_thing(private_linked_list_t);

	this->public.get_count = (int (*) (linked_list_t *)) get_count;
	this->public.create_iterator = (iterator_t * (*) (linked_list_t *,bool))create_iterator;
	this->public.create_enumerator = (enumerator_t*(*)(linked_list_t*))create_enumerator;
	this->public.get_first = (status_t (*) (linked_list_t *, void **item))get_first;
	this->public.get_last = (status_t (*) (linked_list_t *, void **item))get_last;
	this->public.find_first = (status_t (*) (linked_list_t *, linked_list_match_t,void**,...))find_first;
	this->public.find_last = (status_t (*) (linked_list_t *, linked_list_match_t,void**,...))find_last;
	this->public.insert_first = (void (*) (linked_list_t *, void *item))insert_first;
	this->public.insert_last = (void (*) (linked_list_t *, void *item))insert_last;
	this->public.remove_first = (status_t (*) (linked_list_t *, void **item))remove_first;
	this->public.remove_last = (status_t (*) (linked_list_t *, void **item))remove_last;
	this->public.remove = (int(*)(linked_list_t*, void *item, bool (*compare)(void *,void*)))remove_;
	this->public.remove_at = (void(*)(linked_list_t*, enumerator_t *enumerator))remove_at;
	this->public.invoke_offset = (void (*)(linked_list_t*,size_t,...))invoke_offset;
	this->public.invoke_function = (void (*)(linked_list_t*,linked_list_invoke_t,...))invoke_function;
	this->public.clone_offset = (linked_list_t * (*)(linked_list_t*,size_t))clone_offset;
	this->public.clone_function = (linked_list_t * (*)(linked_list_t*,void*(*)(void*)))clone_function;
	this->public.destroy = (void (*) (linked_list_t *))destroy;
	this->public.destroy_offset = (void (*) (linked_list_t *,size_t))destroy_offset;
	this->public.destroy_function = (void (*)(linked_list_t*,void(*)(void*)))destroy_function;

	this->count = 0;
	this->first = NULL;
	this->last = NULL;

	return &this->public;
}