/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   edmunds_karp.c                                     :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: tmaze <tmaze@student.42.fr>                +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2019/03/28 16:21:19 by tmaze             #+#    #+#             */
/*   Updated: 2019/04/13 14:55:19 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)
	{
		if (tab[i].parent != -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		get_score(t_lmdata *data, t_ind **ret)
{
	int		tot;
	int		score;
	int		nb_paths;
	int		i;
	t_ind	*it;

	i = 0;
	tot = 0;
	score = 0;
	while (ret[i])
		i++;
	nb_paths = i;
	i = 0;
	while (ret[i] && (it = ret[i]))
	{
		while (it && tot++)
			it = it->next;
		tot *= (data->nbants / nb_paths);
		if (score == 0 || tot > score)
			score = tot;
		i++;
	}
	return (score);
}

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

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

static t_ind	**resolve_path(int s_ind, int e_ind
							   , int nb_path, t_bfs *tab)
{
	t_ind	**ret;
	int		i;
	int		j;

	i = 0;
	ret = NULL;
	if ((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 = tab[j].parent;
			}
			i++;
		}
	return (ret);
}

t_ind			**edmunds_karp(t_lmdata *data, int start_ind, int end_ind
								, int nb_paths)
{
	t_bfs	tab[data->nb_nodes];
	t_ind	**ret[2];
	int		score[2];

	ret[0] = NULL;
	ret[1] = NULL;
	score[0] = 0;
	score[1] = 0;
	if (data && data->adj)
	{
		bfs(data, tab, start_ind, end_ind);
		while (tab[end_ind].parent != -1)
		{
			update_weights(data, tab, end_ind);
			bfs(data, tab, start_ind, end_ind);
			ret[1] = resolve_path(start_ind, end_ind, nb_paths, tab);
			if (ret[0] == NULL || (score[1] = get_score(data, ret[1])) < score[0])
			{
				score[0] = score[1];
				if (ret[0] != NULL)
					clean_ret(ret[0]);
				ret[0] = ret[1];
			}
			else if (score[1] >= score[0])
			{
				clean_ret(ret[1]);
				break;
			}
		}
		return (ret[0]);
	}
	return (NULL);
}