/*
 * Demo program that uses the Stanford Graphbase and a current
 * routes graphbase to find the shortest path between fixes/airports.
 */
#include <stdio.h>
#include <stdlib.h>

#include <sgb/gb_graph.h>
#include <sgb/gb_save.h>
#include <sgb/gb_dijk.h>

static const char USAGE[] =
"Usage: shortest_path {route.gb filename} {from fix} {to fixes}...\n";

static void
show_dijkstra_result(Vertex *f);

 int main(int argc, char **argv) {
    Graph *g;
    Vertex *f;
    int i;

    if (argc < 4) {
        fprintf(stderr, USAGE);
        exit(EXIT_FAILURE);
    }

    g = restore_graph(argv[1]);
    if (g == NULL) {
        fprintf(stderr, "Cannot restore graph '%s'\n", argv[1]);
        exit(EXIT_FAILURE);
    }

    hash_setup(g);

    f = hash_out(argv[2]);
    if (f == NULL) {
       fprintf(stderr, "Cannot find fix/airport '%s'\n", argv[2]);
       exit(EXIT_FAILURE);
    }

    printf("%s\n", f->name);

    for (i = 3; i < argc; i++) {
        Vertex *t = hash_out(argv[i]);
        int l;

        if (t == NULL) {
            fprintf(stderr, "Cannot find fix/airport '%s'\n", argv[i]);
            exit(EXIT_FAILURE);
        }

        l = dijkstra(f, t, g, NULL);
        show_dijkstra_result(t);
        f = t;
    } 

    exit(EXIT_SUCCESS);
    return 0;
}

static void
show_dijkstra_result(Vertex *f) {
    Vertex *t = NULL, *p = f;
    if (p->backlink == NULL) {
        fprintf(stderr, "No route to '%s'\n", p->name);
        exit(EXIT_FAILURE);
    }

    do {
        Vertex *q = p->backlink;
        p->backlink = t;
        t = p;
        p = q;
    } while (t != p);

    while (t->backlink) {
        Arc *a = t->arcs;
        while (a != NULL && a->tip != t->backlink)
            a = a->next;

        printf("            %-16s %10.1f n.m.\n", a->a.S, a->len / 60.0);
        printf("%s\n", a->tip->name);
        t = t->backlink;
    }

    t = p;
    do {
        Vertex *q = t->backlink;
        t->backlink = p;
        p = t;
        t = q;
    } while (p != f);
}