#include "arg.h"
#include "dbg.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

struct arg
{
    const char *s;
    int (*f)(struct args *, const char *);

    enum
    {
        NOVAL,
        SPACEVAL = 1,
        EQVAL = 1 << 1,
        JOINVAL = 1 << 2
    } v;
};

static int debug(struct args *a, const char *arg)
{
    dbgen = 1;
    return 0;
}

static int inc(struct args *a, const char *arg)
{
    struct arg_input *i = &a->incs;
    size_t n = i->n + 1;
    const char **v = realloc(i->v, n * sizeof *v);

    if (!v)
    {
        perror("realloc(3)");
        return -1;
    }

    v[i->n++] = arg;
    i->v = v;
    return 0;
}

static int opt(struct args *args, const struct arg *a, const char *arg)
{
    const struct arg *prev = args->arg;
    const char *v = arg + strlen(a->s);

    if (prev && prev->v)
    {
        fprintf(stderr, "%s: option '%s' requires a value\n", args->name,
            prev->s);
        return -1;
    }
    else if (*v)
    {
        if (!(a->v & JOINVAL))
        {
            fprintf(stderr, "%s: unrecognized command-line option '%s'\n",
                args->name, arg);
            return -1;
        }
    }
    else if (a->v & SPACEVAL)
    {
        args->arg = a;
        return 0;
    }
    else
        v = NULL;

    return a->f(args, v);
}

int arg(struct args *a, const char *value)
{
    static const struct arg args[] =
    {
        {"-d", debug},
        {"-I", inc, SPACEVAL | JOINVAL}
    };

    const struct arg *prev = a->arg;

    for (size_t i = 0; i < sizeof args / sizeof *args; i++)
    {
        const struct arg *arg = &args[i];

        if (!strncmp(value, arg->s, strlen(arg->s)))
            return opt(a, arg, value);
    }

    if (prev)
    {
        if (*value != '-' && prev->f(a, value))
            return -1;

        a->arg = NULL;
    }
    else if (a->src)
    {
        fprintf(stderr, "%s: only one source file allowed\n", a->name);
        return -1;
    }
    else
        a->src = value;

    return 0;
}

void arg_defaults(struct args *a)
{
}

static void free_input(struct arg_input *i)
{
    free(i->v);
}

void arg_free(struct args *a)
{
    free_input(&a->incs);
}