#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 = 0;
    graph->num_vertices = n;
    
    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");
    if (!file)
        return NULL;
    
    char line[1024];
    if (!fgets(line, sizeof(line), file)) {
        fclose(file);
        return NULL;
    }
    
    int n = atoi(line);
    if (n <= 0) {
        fclose(file);
        return NULL;
    }
    
    Graph *g = graph_new(n);
    if (!g) {
        fclose(file);
        return NULL;
    }
    
    for (int i = 0; i < n; i++) {
        if (!fgets(line, sizeof(line), file)) {
            fprintf(stderr, "Error: Could not read row %d\n", i);
            fclose(file);
            return g;
        }
        
        int j = 0;
        int col = 0;
        while (col < n && line[j] != '\0' && line[j] != '\n') {
            if (line[j] == '1') {
                graph_add_edge(g, i, col);
                col++;
            } else if (line[j] == '0') {
                col++;
            }
            // skip any other characters
            j++;
        }
    }
    
    fclose(file);
    return g;
}

void graph_print(Graph *g) {
    fprintf(stdout, "Number of vertices: %d\n", g->num_vertices);
    fprintf(stdout, "Number of edges: %d\n", g->num_edges);
}

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);
}