/*
 * This file Copyright (C) 2008-2014 Mnemosyne LLC
 *
 * It may be used under the GNU GPL versions 2 or 3
 * or any future license endorsed by Mnemosyne LLC.
 *
 * $Id$
 */

#include <ctype.h> /* isspace () */
#include <stdio.h>
#include <stdlib.h> /* exit () */
#include <string.h>

#include "tr-getopt.h"

#ifndef MAX
 #define MAX(a, b)(((a) > (b)) ? (a) : (b))
#endif

int tr_optind = 1;

static const char*
getArgName (const tr_option * opt)
{
    const char * arg;

    if (!opt->has_arg)
        arg = "";
    else if (opt->argName)
        arg = opt->argName;
    else
        arg = "<args>";

    return arg;
}

static int
get_next_line_len (const char * description, int maxlen)
{
    int end;
    int len = strlen (description);

    if (len < maxlen)
        return len;

    end = maxlen < len ? maxlen : len;
    while ((end > 0) && !isspace (description[end]))
        --end;

    return end ? end : len;
}

static void
getopts_usage_line (const tr_option * opt,
                    int               longWidth,
                    int               shortWidth,
                    int               argWidth)
{
    int len;
    const char * longName   = opt->longName ? opt->longName : "";
    const char * shortName  = opt->shortName ? opt->shortName : "";
    const char * arg        = getArgName (opt);

    const int d_indent = shortWidth + longWidth + argWidth + 7;
    const int d_width = 80 - d_indent;
    const char * d = opt->description;

    printf (" %s%-*s %s%-*s %-*s ",
          (shortName && *shortName ? "-" : " "), shortWidth, shortName,
          (longName && *longName ? "--" : "  "), longWidth, longName,
            argWidth, arg);
    len = get_next_line_len (d, d_width);
    printf ("%*.*s\n", len, len, d);

    d += len;
    while (isspace (*d)) ++d;

    while ((len = get_next_line_len (d, d_width))) {
        printf ("%*.*s%*.*s\n", d_indent, d_indent, "", len, len, d);
        d += len;
        while (isspace (*d)) ++d;
    }
}

static void
maxWidth (const struct tr_option * o,
          int *                    longWidth,
          int *                    shortWidth,
          int *                    argWidth)
{
    const char * arg;

    if (o->longName)
        *longWidth = MAX (*longWidth, (int)strlen (o->longName));

    if (o->shortName)
        *shortWidth = MAX (*shortWidth, (int)strlen (o->shortName));

    if ((arg = getArgName (o)))
        *argWidth = MAX (*argWidth, (int)strlen (arg));
}

void
tr_getopt_usage (const char *           progName,
                 const char *           description,
                 const struct tr_option opts[])
{
    int                      longWidth = 0;
    int                      shortWidth = 0;
    int                      argWidth = 0;
    struct tr_option         help;
    const struct tr_option * o;

    for (o = opts; o->val; ++o)
        maxWidth (o, &longWidth, &shortWidth, &argWidth);

    help.val = -1;
    help.longName = "help";
    help.description = "Display this help page and exit";
    help.shortName = "h";
    help.has_arg = 0;
    maxWidth (&help, &longWidth, &shortWidth, &argWidth);

    if (description == NULL)
        description = "Usage: %s [options]";
    printf (description, progName);
    printf ("\n\nOptions:\n");
    getopts_usage_line (&help, longWidth, shortWidth, argWidth);
    for (o = opts; o->val; ++o)
        getopts_usage_line (o, longWidth, shortWidth, argWidth);
}

static const tr_option *
findOption (const tr_option * opts,
            const char *      str,
            const char **     setme_arg)
{
    size_t            matchlen = 0;
    const char *      arg = NULL;
    const tr_option * o;
    const tr_option * match = NULL;

    /* find the longest matching option */
    for (o = opts; o->val; ++o)
    {
        size_t len = o->longName ? strlen (o->longName) : 0;

        if ((matchlen < len)
          && (str[0] == '-')
          && (str[1] == '-')
          && !strncmp (str+2, o->longName, len)
          && (str[len + 2] == '\0' || (o->has_arg && str[len + 2] == '=')))
        {
            matchlen = len;
            match = o;
            arg = str[len + 2] == '=' ? str + len + 3 : NULL;
        }

        len = o->shortName ? strlen (o->shortName) : 0;

        if ((matchlen < len)
          && (str[0] == '-')
          && !strncmp (str+1, o->shortName, len)
          && (str[len + 1] == '\0' || o->has_arg))
        {
            matchlen = len;
            match = o;
            switch (str[len + 1])
            {
                case '\0':
                    arg = NULL;          break;

                case '=':
                    arg = str + len + 2; break;

                default:
                    arg = str + len + 1; break;
            }
        }
    }

    if (setme_arg)
        *setme_arg = arg;

    return match;
}

int
tr_getopt (const char *      usage,
           int               argc,
           const char **     argv,
           const tr_option * opts,
           const char **     setme_optarg)
{
    int               i;
    const char *      arg = NULL;
    const tr_option * o = NULL;

    *setme_optarg = NULL;

    /* handle the builtin 'help' option */
    for (i = 1; i < argc; ++i)
    {
        if (!strcmp (argv[i], "-h") || !strcmp (argv[i], "--help"))
        {
            tr_getopt_usage (argv[0], usage, opts);
            exit (0);
        }
    }

    /* out of options? */
    if (argc == 1 || tr_optind >= argc)
        return TR_OPT_DONE;

    o = findOption (opts, argv[tr_optind], &arg);
    if (!o)
    {
        /* let the user know we got an unknown option... */
        *setme_optarg = argv[tr_optind++];
        return TR_OPT_UNK;
    }

    if (!o->has_arg)
    {
        /* no argument needed for this option, so we're done */
        if (arg)
            return TR_OPT_ERR;
        *setme_optarg = NULL;
        ++tr_optind;
        return o->val;
    }

    /* option needed an argument, and it was embedded in this string */
    if (arg)
    {
        *setme_optarg = arg;
        ++tr_optind;
        return o->val;
    }

    /* throw an error if the option needed an argument but didn't get one */
    if (++tr_optind >= argc)
        return TR_OPT_ERR;
    if (findOption (opts, argv[tr_optind], NULL))
        return TR_OPT_ERR;

    *setme_optarg = argv[tr_optind++];
    return o->val;
}