/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   edmunds_karp.c                                     :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: tmaze <tmaze@student.42.fr>                +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2019/03/28 16:21:19 by tmaze             #+#    #+#             */
/*   Updated: 2019/04/05 15:13:53 by tmaze            ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */

#include "lem_in.h"

static void		update_weights(t_lmdata *data, t_bfs *tab, int end_ind)
{
	t_ind	*it;
	int		i;

	i = end_ind;
	while (i != -1)
	{
		it = data->adj[tab[i].parent];
		while (it && it->index != i)
			it = it->next;
		if (it && it->index == i)
			it->weight--;
		it = data->adj[i];
		while (it && it->index != tab[i].parent)
			it = it->next;
		if (it && it->index == tab[i].parent)
			it->weight++;
		i = tab[i].parent;
	}
}

static int		reset_weights(t_lmdata *data, int s_ind, int node)
{
	t_ind	*it;
	t_ind	*it2;

	it = data->adj[node];
	while (it && it->weight != 2)
		it = it->next;
	if (it && it->weight == 2)
		it->weight--;
	it2 = data->adj[it->index];
	while (it2 && it2->index != node)
		it2 = it2->next;
	if (it2 && it2->index == node)
		it2->weight++;
	return ((node == s_ind) ? -1 : it->index);
}

static t_ind	**clean_ret(t_ind **ret)
{
	tablst_inddel(ret);
	return (NULL);
}

t_ind			**resolve_path(t_lmdata *data, int s_ind, int e_ind
								, int nb_path)
{
	t_ind	**ret;
	int		i;
	int		j;

	ret = NULL;
	i = 0;
	if (nb_path > 0 && (ret = (t_ind**)ft_memalloc(sizeof(t_ind*)
		* (nb_path + 1))) != NULL)
	{
		while (i < nb_path && (j = e_ind) == e_ind)
		{
			while (j != s_ind)
			{
				if (lst_indadd(&(ret[i]), j) == NULL)
					return (clean_ret(ret));
				j = reset_weights(data, s_ind, j);
			}
			i++;
		}
	}
	return (ret);
}

t_ind			**edmunds_karp(t_lmdata *data, int start_ind, int end_ind)
{
	t_bfs	tab[data->nb_nodes];
	int		nb_path;

	nb_path = 0;
	if (data && data->adj)
	{
		bfs(data, tab, start_ind, end_ind);
		while (tab[end_ind].parent != -1)
		{
			nb_path++;
			update_weights(data, tab, end_ind);
			bfs(data, tab, start_ind, end_ind);
		}
		return (resolve_path(data, start_ind, end_ind, nb_path));
	}
	return (NULL);
}