/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */

/** @file getoptdata.cpp Library for parsing command line options. */

#include "../stdafx.h"
#include "getoptdata.h"

#include "../safeguards.h"

/**
 * Find the next option.
 * @return Function returns one
 * - An option letter if it found another option.
 * - -1 if option processing is finished. Inspect #argv and #numleft to find the command line arguments.
 * - -2 if an error was encountered.
 */
int GetOptData::GetOpt()
{
	const OptionData *odata;

	char *s = this->cont;
	if (s == nullptr) {
		if (this->numleft == 0) return -1; // No arguments left -> finished.

		s = this->argv[0];
		if (*s != '-') return -1; // No leading '-' -> not an option -> finished.

		this->argv++;
		this->numleft--;

		/* Is it a long option? */
		for (odata = this->options; odata->flags != ODF_END; odata++) {
			if (odata->longname != nullptr && !strcmp(odata->longname, s)) { // Long options always use the entire argument.
				this->cont = nullptr;
				goto set_optval;
			}
		}

		s++; // Skip leading '-'.
	}

	/* Is it a short option? */
	for (odata = this->options; odata->flags != ODF_END; odata++) {
		if (odata->shortname != '\0' && *s == odata->shortname) {
			this->cont = (s[1] != '\0') ? s + 1 : nullptr;

set_optval: // Handle option value of *odata .
			this->opt = nullptr;
			switch (odata->flags) {
				case ODF_NO_VALUE:
					return odata->id;

				case ODF_HAS_VALUE:
				case ODF_OPTIONAL_VALUE:
					if (this->cont != nullptr) { // Remainder of the argument is the option value.
						this->opt = this->cont;
						this->cont = nullptr;
						return odata->id;
					}
					/* No more arguments, either return an error or a value-less option. */
					if (this->numleft == 0) return (odata->flags == ODF_HAS_VALUE) ? -2 : odata->id;

					/* Next argument looks like another option, let's not return it as option value. */
					if (odata->flags == ODF_OPTIONAL_VALUE && this->argv[0][0] == '-') return odata->id;

					this->opt = this->argv[0]; // Next argument is the option value.
					this->argv++;
					this->numleft--;
					return odata->id;

				default: NOT_REACHED();
			}
		}
	}

	return -2; // No other ways to interpret the text -> error.
}