#include <stdint.h>
#include <stdio.h>
#include <getopt.h>

#include "cli.h"

/* Internal bitmask helpers */
#define HAS_FLAG(flags, flag)	((flags) & (flag))
#define SET_FLAG(flags, flag)	((flags) |= (flag))

/* Map -? to -h to support help shortcut */
#define HANDLE_QUESTION_MARK(opt) \
	do { \
		if (opt == '?' && (optopt) == '?') \
		opt = 'h'; \
	} while (0)

/* Forward declarations */
static void build_long_options(struct option *long_opts, size_t nb_opts,
		const struct option_descriptor *src);
static void build_optstr(char *dest, const struct option_descriptor *opts,
		size_t nb_opts);
static const struct option_descriptor *find_option_handler(int opt,
		const struct option_descriptor *opts, size_t nb_opts);
static int handle_one_option(int opt, char **argv, void *config,
		uint64_t *opt_tracker,
		const struct option_descriptor *opts, size_t nb_opts);
static enum cli_code error_unknown_opt(const char *current_opt);
static enum cli_code error_invalid_opt(const char *current_opt);
static enum cli_code error_duplicate_opt(const char *current_opt);
static void print_suggest_help(void);
/* ------------------- */

static const char *s_prog_name = "";

void
cli_set_prog_name(const char *name)
{
	if (NULL != name)
		s_prog_name = name;
}

enum cli_code
cli_parse(int argc, char **argv, void *config,
	const struct option_descriptor *opts, size_t nb_opts,
	char *opt_str, struct option *long_opts)
{
	uint64_t tracker = 0;
	int opt;
	int res;

	build_optstr(opt_str, opts, nb_opts);
	build_long_options(long_opts, nb_opts, opts);
	while (-1 != (opt = getopt_long(argc, argv, opt_str, long_opts, NULL)))
	{
		HANDLE_QUESTION_MARK(opt);
		res = handle_one_option(opt, argv, config, &tracker, opts, nb_opts);
		if (CLI_SUCCESS != res)
			return (enum cli_code)res;
	}
	return CLI_SUCCESS;
}

static void
build_optstr(char *dest, const struct option_descriptor *opts, size_t nb_opts)
{
	size_t str_i = 1;

	/* Mute default error messages */
	dest[0] = ':';

	for (size_t opt_i = 0; opt_i < nb_opts; ++opt_i)
	{
		dest[str_i++] = opts[opt_i].short_opt;
		switch (opts[opt_i].has_arg)
		{
			case optional_argument: dest[str_i++] = ':'; /* fall through */
			case required_argument: dest[str_i++] = ':'; break;
			default: break;
		}
	}
	dest[str_i] = '\0';
}

static int
handle_one_option(int opt, char **argv, void *config,
	uint64_t *opt_tracker,
	const struct option_descriptor *opts, size_t nb_opts)
{
	const char *current_opt = argv[optind - 1];
	const struct option_descriptor *desc;
	size_t bitmask_index;
	int res;

	if ('?' == opt)
		return error_unknown_opt(current_opt);
	else if (':' == opt)
		return error_invalid_opt(current_opt);

	desc = find_option_handler(opt, opts, nb_opts);
	if (NULL == desc)
		return CLI_ERROR;
	bitmask_index = (size_t)(desc - opts);
	if (HAS_FLAG(*opt_tracker, (1ULL << bitmask_index)))
		return error_duplicate_opt(current_opt);

	SET_FLAG(*opt_tracker, (1ULL << bitmask_index));
	res = desc->handler(optarg, config);
	if (CLI_ERROR == res)
		return error_invalid_opt(current_opt);
	return res;
}

static void
build_long_options(struct option *long_opts, size_t nb_opts,
	const struct option_descriptor *src)
{
	for (size_t i = 0; i < nb_opts; ++i)
	{
		long_opts[i].name = src[i].long_opt;
		long_opts[i].has_arg = src[i].has_arg;
		long_opts[i].flag = NULL;
		long_opts[i].val = src[i].short_opt;
	}
	long_opts[nb_opts] = (struct option){0};
}

static const struct option_descriptor *
find_option_handler(int opt, const struct option_descriptor *opts,
	size_t nb_opts)
{
	for (size_t i = 0; i < nb_opts; ++i)
	{
		if (opts[i].short_opt == opt)
			return &opts[i];
	}
	return NULL;
}

static enum cli_code
error_unknown_opt(const char *current_opt)
{
	fprintf(stderr, "%s: unknown option -- '%s'\n", s_prog_name, current_opt);
	print_suggest_help();
	return CLI_ERROR;
}

static enum cli_code
error_invalid_opt(const char *current_opt)
{
	fprintf(stderr, "%s: invalid option '%s'\n", s_prog_name, current_opt);
	print_suggest_help();
	return CLI_ERROR;
}

static enum cli_code
error_duplicate_opt(const char *current_opt)
{
	fprintf(stderr, "%s: duplicate option '%s'\n", s_prog_name, current_opt);
	print_suggest_help();
	return CLI_ERROR;
}

static void
print_suggest_help(void)
{
	fprintf(stderr, "Try '%s --help' for more information.\n", s_prog_name);
}