/*
**********************************************************************************************
*	File: maat_group.cpp
*   Description: 
*	Authors: Liu wentan <liuwentan@geedgenetworks.com>
*	Date:    2022-10-31
*   Copyright: (c) 2018-2022 Geedge Networks, Inc. All rights reserved.
***********************************************************************************************
*/

#include <assert.h>
#include <pthread.h>

#include "maat_group.h"
#include "utils.h"
#include "maat_utils.h"
#include "uthash/uthash.h"
#include "igraph/igraph.h"
#include "log/log.h"

#define MODULE_GROUP	 module_name_str("maat.group")

struct maat_group_topology {
    struct maat_group *hash_group_by_id;	 //key: group_id, value: struct maat_group *.
	struct maat_group *hash_group_by_vertex; //key: vetex_id, value: struct maat_group *. Multimap (Items with multiple keys).
    igraph_t group_graph;
	igraph_integer_t group_graph_vcount;
	igraph_vector_t dfs_vids;
	igraph_integer_t grp_vertex_id_generator;

    pthread_rwlock_t rwlock;
    struct log_handle *logger;
};

void group_vertex_free(struct maat_group *group)
{
	free(group->top_group_ids);
	free(group);
}

struct maat_group_topology *maat_group_topology_new(struct log_handle *logger)
{
    struct maat_group_topology *group_topo = ALLOC(struct maat_group_topology, 1);
    UNUSED int ret = 0;

    group_topo->hash_group_by_id = NULL;
    group_topo->hash_group_by_vertex = NULL;

    ret = igraph_empty(&group_topo->group_graph, 0, IGRAPH_DIRECTED);
    assert(ret == IGRAPH_SUCCESS);

    ret = pthread_rwlock_init(&group_topo->rwlock, NULL);
    assert(ret == 0);

    group_topo->logger = logger;

    return group_topo;
}

void maat_group_topology_free(struct maat_group_topology *group_topo)
{
    struct maat_group *group = NULL, *tmp_group = NULL;

    HASH_CLEAR(hh_vertex_id, group_topo->hash_group_by_vertex);//No need group memory clean up.
	HASH_ITER(hh_group_id, group_topo->hash_group_by_id, group, tmp_group) {
		HASH_DELETE(hh_group_id, group_topo->hash_group_by_id, group);
		group_vertex_free(group);
	}
	assert(group_topo->hash_group_by_id == NULL);	
	
	igraph_destroy(&group_topo->group_graph);

    pthread_rwlock_unlock(&group_topo->rwlock);
	pthread_rwlock_destroy(&group_topo->rwlock);
}

size_t print_igraph_vector(igraph_vector_t *v, char *buff, size_t sz) {
  long int i;
  int printed = 0;

  for (i = 0; i < igraph_vector_size(v); i++) {
    printed += snprintf(buff + printed, sz - printed, " %li", (long int) VECTOR(*v)[i]);
  }

  return printed;
}

struct maat_group *maat_group_topology_add_group(struct maat_group_topology *group_topo, int group_id)
{
	struct maat_group *group = ALLOC(struct maat_group, 1);

	group->group_id = group_id;
	group->vertex_id = group_topo->grp_vertex_id_generator++;

	assert(igraph_vcount(&group_topo->group_graph)==group->vertex_id);
	igraph_add_vertices(&group_topo->group_graph, 1, NULL);	//Add 1 vertice.
	
	HASH_ADD(hh_group_id, group_topo->hash_group_by_id, group_id, sizeof(group->group_id), group);
	HASH_ADD(hh_vertex_id, group_topo->hash_group_by_vertex, vertex_id, sizeof(group->vertex_id), group);

	return group;
}

void maat_group_topology_remove_group(struct maat_group_topology *group_topo, struct maat_group *group)
{
	igraph_vector_t v; 
	char buff[4096] = {0};

	assert(group->ref_by_compile_cnt == 0 && group->ref_by_superior_group_cnt == 0);
	igraph_vector_init(&v, 8);
	igraph_neighbors(&group_topo->group_graph, &v, group->vertex_id, IGRAPH_ALL);
	if (igraph_vector_size(&v) > 0) {
		print_igraph_vector(&v, buff, sizeof(buff));
		log_error(group_topo->logger, MODULE_GROUP, "Del group %d exception, still reached by %s.",
						                            group->vertex_id, buff);
		assert(0);
	}
	igraph_vector_destroy(&v);
	assert(group->top_group_ids==NULL);
	//We should not call igraph_delete_vertices, because this is function changes the ids of the vertices.
	//igraph_delete_vertices(&hier->group_graph, igraph_vss_1(group->vertex_id));

	
	HASH_DELETE(hh_group_id, group_topo->hash_group_by_id, group);
	HASH_DELETE(hh_vertex_id, group_topo->hash_group_by_vertex, group);

	group_vertex_free(group);
}

struct maat_group *maat_group_topology_find_group(struct maat_group_topology *group_topo, int group_id)
{
    struct maat_group *group = NULL;

    HASH_FIND(hh_group_id, group_topo->hash_group_by_id, &group_id, sizeof(group_id), group);

    return group;
}

int maat_group_topology_add_group_to_group(struct maat_group_topology *group_topo, int group_id, int superior_group_id)
{
    int ret = 0;
	igraph_integer_t edge_id;
	struct maat_group *group = NULL, *superior_group = NULL;

    group = maat_group_topology_find_group(group_topo, group_id);
	if (NULL == group) {
		group = maat_group_topology_add_group(group_topo, group_id);
	}
	
    superior_group = maat_group_topology_find_group(group_topo, superior_group_id);
	if (NULL == superior_group) {
		superior_group = maat_group_topology_add_group(group_topo, superior_group_id);
	}

	ret = igraph_get_eid(&group_topo->group_graph, &edge_id, group->vertex_id, superior_group->vertex_id, IGRAPH_DIRECTED, /*error*/ 0);
	
    //No duplicated edges between two groups.
    if (edge_id > 0) {
		log_error(group_topo->logger, MODULE_GROUP,
                  "Add group %d to group %d failed, relation already exisited.",
				  group->group_id, superior_group->group_id);
		ret = -1;
	} else {
		igraph_add_edge(&group_topo->group_graph, group->vertex_id, superior_group->vertex_id);
		group->ref_by_superior_group_cnt++;
		superior_group->ref_by_subordinate_group_cnt++;
		ret = 0;
	}
	
	return ret;
}

int maat_group_topology_remove_group_from_group(struct maat_group_topology *group_topo, int group_id, int superior_group_id)
{
    int ret = 0;
	struct maat_group *group = NULL, *superior_group = NULL;

	//No hash write operation, LOCK protection is unnecessary.
	group = maat_group_topology_find_group(group_topo, group_id);
	if (NULL == group) {
		log_error(group_topo->logger, MODULE_GROUP,
				  "Del group %d from group %d failed, group %d not exisited.",
				  group_id, superior_group_id, group_id);
		return -1;	
	}

    superior_group = maat_group_topology_find_group(group_topo, superior_group_id);
	if (NULL == superior_group) {
		log_error(group_topo->logger, MODULE_GROUP,
				  "Del group %d from group %d failed, superior group %d not exisited.",
				  group_id, superior_group_id, superior_group_id);
		return -1;	
	}

	igraph_es_t es;
	igraph_integer_t edge_num_before = 0, edge_num_after = 0;

	edge_num_before = igraph_ecount(&group_topo->group_graph);
	// The edges between the given pairs of vertices will be included in the edge selection.
	//The vertex pairs must be given as the arguments of the function call, the third argument 
	//is the first vertex of the first edge, the fourth argument is the second vertex of the 
	//first edge, the fifth is the first vertex of the second edge and so on. The last element
	//of the argument list must be -1 to denote the end of the argument list.
	//https://igraph.org/c/doc/igraph-Iterators.html#igraph_es_pairs_small
	ret = igraph_es_pairs_small(&es, IGRAPH_DIRECTED, group->vertex_id, superior_group->vertex_id, -1);
	assert(ret==IGRAPH_SUCCESS);
	// ignore no such edge to abort().
	igraph_set_error_handler(igraph_error_handler_ignore);
	ret = igraph_delete_edges(&group_topo->group_graph, es);
	edge_num_after = igraph_ecount(&group_topo->group_graph);
	igraph_es_destroy(&es);
	
	if (ret != IGRAPH_SUCCESS || edge_num_before - edge_num_after != 1) {
		assert(0);
		return -1;
	}

	group->ref_by_superior_group_cnt--;
	superior_group->ref_by_subordinate_group_cnt--;

	return 0;
}

static size_t effective_vertices_count(igraph_vector_t *vids)
{
    size_t i = 0;
	int tmp_vid = 0;

	for (i = 0; i < (size_t)igraph_vector_size(vids); i++) {
		tmp_vid = (int) VECTOR(*vids)[i];
		if (tmp_vid < 0) {
			break;
		}
	}

	return i;
}

int maat_group_topology_build_top_groups(struct maat_group_topology *group_topo)
{
	struct maat_group *group = NULL, *tmp = NULL;
	struct maat_group *superior_group = NULL;
	int tmp_vid=0;
	size_t i=0, top_group_cnt=0;
	int* temp_group_ids=NULL;
	
	igraph_bool_t is_dag;
	igraph_is_dag(&(group_topo->group_graph), &is_dag);
	if (!is_dag) {
		log_error(group_topo->logger, MODULE_GROUP, "Sub group cycle detected!");
		return -1;
	}

	group_topo->group_graph_vcount = igraph_vcount(&group_topo->group_graph);
	igraph_vector_init(&(group_topo->dfs_vids), group_topo->group_graph_vcount);
	
	HASH_ITER (hh_group_id, group_topo->hash_group_by_id, group, tmp) {
		top_group_cnt = 0;
		temp_group_ids = NULL;
		//Orphan, Not reference by any one, free it.
		if (0 == group->ref_by_compile_cnt
			&& 0 == group->ref_by_superior_group_cnt
			&& 0 == group->ref_by_subordinate_group_cnt
			&& 0 == group->ref_by_item_cnt) {
		
			FREE(group->top_group_ids);
			maat_group_topology_remove_group(group_topo, group);
			continue;
		}

		//A group is need to build top groups when it has items and referenced by superior groups or compiles.
		if (group->ref_by_item_cnt > 0 && 
            (group->ref_by_compile_cnt > 0 || group->ref_by_superior_group_cnt > 0)) {
			if (0 == group->ref_by_superior_group_cnt) {
				//fast path, group is only referenced by compile rules.
				top_group_cnt = 1;
				temp_group_ids = ALLOC(int, top_group_cnt);
				temp_group_ids[0] = group->group_id;
			} else {
				igraph_vector_t *vids = &(group_topo->dfs_vids);
				igraph_dfs(&group_topo->group_graph, group->vertex_id, IGRAPH_OUT, 
							0, vids, NULL, NULL, NULL, NULL, NULL, NULL);
				
				temp_group_ids = ALLOC(int, effective_vertices_count(vids));
				
				for (size_t i = 0; i < (size_t)igraph_vector_size(vids); i++) {
					tmp_vid = (int) VECTOR(*vids)[i];
					if (tmp_vid < 0) {
						break;
					}

					HASH_FIND(hh_vertex_id, group_topo->hash_group_by_vertex, &tmp_vid, sizeof(tmp_vid), superior_group);

                    //including itself
					if (superior_group->ref_by_compile_cnt > 0) {
						temp_group_ids[top_group_cnt] = superior_group->group_id;
						top_group_cnt++;
					}
				}
			}
		}

		free(group->top_group_ids);
		group->top_group_cnt = top_group_cnt;
		group->top_group_ids = ALLOC(int, group->top_group_cnt);
		memcpy(group->top_group_ids, temp_group_ids, sizeof(int)*group->top_group_cnt);

		FREE(temp_group_ids);
	}	
	igraph_vector_destroy(&group_topo->dfs_vids);

	return 0;
}