#include "git-compat-util.h"
#include "parse-options.h"
#include "strbuf.h"

#define OPT_SHORT 1
#define OPT_UNSET 2

struct optparse_t {
        const char **argv;
        int argc;
        const char *opt;
};

static inline const char *get_arg(struct optparse_t *p)
{
        if (p->opt) {
                const char *res = p->opt;
                p->opt = NULL;
                return res;
        }
        p->argc--;
        return *++p->argv;
}

static inline const char *skip_prefix(const char *str, const char *prefix)
{
        size_t len = strlen(prefix);
        return strncmp(str, prefix, len) ? NULL : str + len;
}

static int opterror(const struct option *opt, const char *reason, int flags)
{
        if (flags & OPT_SHORT)
                return error("switch `%c' %s", opt->short_name, reason);
        if (flags & OPT_UNSET)
                return error("option `no-%s' %s", opt->long_name, reason);
        return error("option `%s' %s", opt->long_name, reason);
}

static int get_value(struct optparse_t *p,
                     const struct option *opt, int flags)
{
        const char *s;

        if (p->opt && (flags & OPT_UNSET))
                return opterror(opt, "takes no value", flags);

        switch (opt->type) {
        case OPTION_BOOLEAN:
                if (!(flags & OPT_SHORT) && p->opt)
                        return opterror(opt, "takes no value", flags);
                if (flags & OPT_UNSET)
                        *(int *)opt->value = 0;
                else
                        (*(int *)opt->value)++;
                return 0;

        case OPTION_STRING:
                if (flags & OPT_UNSET) {
                        *(const char **)opt->value = (const char *)NULL;
                        return 0;
                }
                if (!p->opt && p->argc <= 1)
                        return opterror(opt, "requires a value", flags);
                *(const char **)opt->value = get_arg(p);
                return 0;

        case OPTION_INTEGER:
                if (flags & OPT_UNSET) {
                        *(int *)opt->value = 0;
                        return 0;
                }
                if (!p->opt && p->argc <= 1)
                        return opterror(opt, "requires a value", flags);
                *(int *)opt->value = strtol(get_arg(p), (char **)&s, 10);
                if (*s)
                        return opterror(opt, "expects a numerical value", flags);
                return 0;

        default:
                die("should not happen, someone must be hit on the forehead");
        }
}

static int parse_short_opt(struct optparse_t *p, const struct option *options)
{
        for (; options->type != OPTION_END; options++) {
                if (options->short_name == *p->opt) {
                        p->opt = p->opt[1] ? p->opt + 1 : NULL;
                        return get_value(p, options, OPT_SHORT);
                }
        }
        return error("unknown switch `%c'", *p->opt);
}

static int parse_long_opt(struct optparse_t *p, const char *arg,
                          const struct option *options)
{
        for (; options->type != OPTION_END; options++) {
                const char *rest;
                int flags = 0;

                if (!options->long_name)
                        continue;

                rest = skip_prefix(arg, options->long_name);
                if (!rest) {
                        if (strncmp(arg, "no-", 3))
                                continue;
                        flags |= OPT_UNSET;
                        rest = skip_prefix(arg + 3, options->long_name);
                        if (!rest)
                                continue;
                }
                if (*rest) {
                        if (*rest != '=')
                                continue;
                        p->opt = rest + 1;
                }
                return get_value(p, options, flags);
        }
        return error("unknown option `%s'", arg);
}

int parse_options(int argc, const char **argv, const struct option *options,
                  const char * const usagestr[], int flags)
{
        struct optparse_t args = { argv + 1, argc - 1, NULL };
        int j = 0;

        for (; args.argc; args.argc--, args.argv++) {
                const char *arg = args.argv[0];

                if (*arg != '-' || !arg[1]) {
                        argv[j++] = args.argv[0];
                        continue;
                }

                if (arg[1] != '-') {
                        args.opt = arg + 1;
                        do {
                                if (*args.opt == 'h')
                                        usage_with_options(usagestr, options);
                                if (parse_short_opt(&args, options) < 0)
                                        usage_with_options(usagestr, options);
                        } while (args.opt);
                        continue;
                }

                if (!arg[2]) { /* "--" */
                        if (!(flags & PARSE_OPT_KEEP_DASHDASH)) {
                                args.argc--;
                                args.argv++;
                        }
                        break;
                }

                if (!strcmp(arg + 2, "help"))
                        usage_with_options(usagestr, options);
                if (parse_long_opt(&args, arg + 2, options))
                        usage_with_options(usagestr, options);
        }

        memmove(argv + j, args.argv, args.argc * sizeof(*argv));
        argv[j + args.argc] = NULL;
        return j + args.argc;
}

#define USAGE_OPTS_WIDTH 24
#define USAGE_GAP         2

void usage_with_options(const char * const *usagestr,
                        const struct option *opts)
{
        struct strbuf sb;

        strbuf_init(&sb, 4096);
        strbuf_addstr(&sb, *usagestr);
        strbuf_addch(&sb, '\n');
        while (*++usagestr)
                strbuf_addf(&sb, "    %s\n", *usagestr);

        if (opts->type != OPTION_GROUP)
                strbuf_addch(&sb, '\n');

        for (; opts->type != OPTION_END; opts++) {
                size_t pos;
                int pad;

                if (opts->type == OPTION_GROUP) {
                        strbuf_addch(&sb, '\n');
                        if (*opts->help)
                                strbuf_addf(&sb, "%s\n", opts->help);
                        continue;
                }

                pos = sb.len;
                strbuf_addstr(&sb, "    ");
                if (opts->short_name)
                        strbuf_addf(&sb, "-%c", opts->short_name);
                if (opts->long_name && opts->short_name)
                        strbuf_addstr(&sb, ", ");
                if (opts->long_name)
                        strbuf_addf(&sb, "--%s", opts->long_name);

                switch (opts->type) {
                case OPTION_INTEGER:
                        strbuf_addstr(&sb, " <n>");
                        break;
                case OPTION_STRING:
                        if (opts->argh)
                                strbuf_addf(&sb, " <%s>", opts->argh);
                        else
                                strbuf_addstr(&sb, " ...");
                        break;
                default:
                        break;
                }

                pad = sb.len - pos;
                if (pad <= USAGE_OPTS_WIDTH)
                        pad = USAGE_OPTS_WIDTH - pad;
                else {
                        strbuf_addch(&sb, '\n');
                        pad = USAGE_OPTS_WIDTH;
                }
                strbuf_addf(&sb, "%*s%s\n", pad + USAGE_GAP, "", opts->help);
        }
        usage(sb.buf);
}