#include "graph.h"
#include "linked_list.h"
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>

// Need to declare 'graph_delete' for use in 'graph_new'
void graph_delete(Graph *g);

Graph *graph_new(int n) {
    Graph *graph = (Graph *)malloc(sizeof(Graph));
    if (!graph)
        return NULL;

    graph->vertices = (Vertex *)malloc(sizeof(Vertex) * n);
    if (!graph->vertices) {
        free(graph);
        return NULL;
    }

    graph->num_edges = n;
    graph->num_vertices = 0;
    
    for (int i = 0; i < n; i++) {
        graph->vertices[i].id = i;
        graph->vertices[i].out_neighbours = linked_list_new();
        graph->vertices[i].in_neighbours = linked_list_new();

        // if allocation for the linked lists failed
        if (!graph->vertices[i].out_neighbours
            || !graph->vertices[i].in_neighbours) {
            graph_delete(graph);
            return NULL;
        }
    }

    return graph;
}

void graph_add_edge(Graph *g, int i, int j) {
    linked_list_append(g->vertices[i].out_neighbours, &g->vertices[j]);
    linked_list_append(g->vertices[j].in_neighbours, &g->vertices[i]);
    g->num_edges++;
}

void graph_remove_edge(Graph *g, int i, int j) {
    LinkedListNode *in_node = linked_list_find(
        g->vertices[i].out_neighbours,
        &g->vertices[j]);
    LinkedListNode *out_node = linked_list_find(
        g->vertices[j].in_neighbours,
        &g->vertices[j]);
    linked_list_remove(g->vertices[i].out_neighbours, in_node);
    linked_list_remove(g->vertices[j].in_neighbours, out_node);
    g->num_edges--;
}

Graph *graph_read(const char *filename) {
    FILE *file = fopen(filename, "r");
    char line[1024];
    fgets(line, 1024, file);

    int n = atoi(line);
    if (!n)
        return NULL;
    Graph *g = graph_new(n);

    char c = line[0];
    int i, j = 0;
    while (fgets(line, 1024, file)) {
        while (c != '\n') {
            if (c == '1') {
                graph_add_edge(g, i, j);
                j++;
            } else if (c == '0') {
                j++;
            }
            c++;
        }
        i++;
    }

    return g;
}

void graph_delete(Graph *g) {
    for (int i = 0; i < g->num_vertices; i++) {
        linked_list_delete(g->vertices[i].in_neighbours);
        linked_list_delete(g->vertices[i].out_neighbours);
    }
    free(g->vertices);
    free(g);
}