#include <assert.h>
#include <string.h>
#include <stdio.h>
#include "error_util.h"
#include "command-line-arguments.h"

typedef enum {
    OPT_FAILED,         /* false */
    OPT_OK,             /* good */
    OPT_GIVEBACK,       /* pop one of the arguments you thought you were getting off the stack */
} opt_handled;

/*
 * Search the array of keywords for a given argument, assigning the
 * output variable to the corresponding value.  Return false if nothing
 * matches.
 */

static opt_handled
_process_keyword_arg (const notmuch_opt_desc_t *arg_desc, char next,
		      const char *arg_str, bool negate)
{
    const notmuch_keyword_t *keywords;

    if (next == '\0') {
	/* No keyword given */
	arg_str = "";
    }

    for (keywords = arg_desc->keywords; keywords->name; keywords++) {
	if (strcmp (arg_str, keywords->name) != 0)
	    continue;

	if (arg_desc->opt_flags && negate)
	    *arg_desc->opt_flags &= ~keywords->value;
	else if (arg_desc->opt_flags)
	    *arg_desc->opt_flags |= keywords->value;
	else
	    *arg_desc->opt_keyword = keywords->value;

	return OPT_OK;
    }

    if (arg_desc->opt_keyword && arg_desc->keyword_no_arg_value && next != ':' && next != '=') {
	for (keywords = arg_desc->keywords; keywords->name; keywords++) {
	    if (strcmp (arg_desc->keyword_no_arg_value, keywords->name) != 0)
		continue;

	    *arg_desc->opt_keyword = keywords->value;
	    fprintf (stderr,
		     "Warning: No known keyword option given for \"%s\", choosing value \"%s\"."
		     "  Please specify the argument explicitly!\n", arg_desc->name,
		     arg_desc->keyword_no_arg_value);

	    return OPT_GIVEBACK;
	}
	fprintf (stderr,
		 "No matching keyword for option \"%s\" and default value \"%s\" is invalid.\n",
		 arg_str,
		 arg_desc->name);
	return OPT_FAILED;
    }

    if (next != '\0')
	fprintf (stderr, "Unknown keyword argument \"%s\" for option \"%s\".\n", arg_str,
		 arg_desc->name);
    else
	fprintf (stderr, "Option \"%s\" needs a keyword argument.\n", arg_desc->name);
    return OPT_FAILED;
}

static opt_handled
_process_boolean_arg (const notmuch_opt_desc_t *arg_desc, char next,
		      const char *arg_str, bool negate)
{
    bool value;

    if (next == '\0' || strcmp (arg_str, "true") == 0) {
	value = true;
    } else if (strcmp (arg_str, "false") == 0) {
	value = false;
    } else {
	fprintf (stderr, "Unknown argument \"%s\" for (boolean) option \"%s\".\n", arg_str,
		 arg_desc->name);
	return OPT_FAILED;
    }

    *arg_desc->opt_bool = negate ? (! value) : value;

    return OPT_OK;
}

static opt_handled
_process_int_arg (const notmuch_opt_desc_t *arg_desc, char next, const char *arg_str)
{

    char *endptr;

    if (next == '\0' || arg_str[0] == '\0') {
	fprintf (stderr, "Option \"%s\" needs an integer argument.\n", arg_desc->name);
	return OPT_FAILED;
    }

    *arg_desc->opt_int = strtol (arg_str, &endptr, 10);
    if (*endptr == '\0')
	return OPT_OK;

    fprintf (stderr, "Unable to parse argument \"%s\" for option \"%s\" as an integer.\n",
	     arg_str, arg_desc->name);
    return OPT_FAILED;
}

static opt_handled
_process_string_arg (const notmuch_opt_desc_t *arg_desc, char next, const char *arg_str)
{

    if (next == '\0') {
	fprintf (stderr, "Option \"%s\" needs a string argument.\n", arg_desc->name);
	return OPT_FAILED;
    }
    if (arg_str[0] == '\0' && ! arg_desc->allow_empty) {
	fprintf (stderr, "String argument for option \"%s\" must be non-empty.\n", arg_desc->name);
	return OPT_FAILED;
    }
    *arg_desc->opt_string = arg_str;
    return OPT_OK;
}

/* Return number of non-NULL opt_* fields in opt_desc. */
static int
_opt_set_count (const notmuch_opt_desc_t *opt_desc)
{
    return
	(bool) opt_desc->opt_inherit +
	(bool) opt_desc->opt_bool +
	(bool) opt_desc->opt_int +
	(bool) opt_desc->opt_keyword +
	(bool) opt_desc->opt_flags +
	(bool) opt_desc->opt_string +
	(bool) opt_desc->opt_position;
}

/* Return true if opt_desc is valid. */
static bool
_opt_valid (const notmuch_opt_desc_t *opt_desc)
{
    int n = _opt_set_count (opt_desc);

    if (n > 1)
	INTERNAL_ERROR ("more than one non-NULL opt_* field for argument \"%s\"",
			opt_desc->name);

    return n > 0;
}

/*
 * Search for the {pos_arg_index}th position argument, return false if
 * that does not exist.
 */

bool
parse_position_arg (const char *arg_str, int pos_arg_index,
		    const notmuch_opt_desc_t *arg_desc)
{

    int pos_arg_counter = 0;

    while (_opt_valid (arg_desc)) {
	if (arg_desc->opt_position) {
	    if (pos_arg_counter == pos_arg_index) {
		*arg_desc->opt_position = arg_str;
		if (arg_desc->present)
		    *arg_desc->present = true;
		return true;
	    }
	    pos_arg_counter++;
	}
	arg_desc++;
    }
    return false;
}

#define NEGATIVE_PREFIX "no-"

/*
 * Search for a non-positional (i.e. starting with --) argument matching arg,
 * parse a possible value, and assign to *output_var
 */

int
parse_option (int argc, char **argv, const notmuch_opt_desc_t *options, int opt_index)
{
    assert (argv);

    const char *_arg = argv[opt_index];

    assert (_arg);
    assert (options);

    const char *arg = _arg + 2; /* _arg starts with -- */
    const char *negative_arg = NULL;

    /* See if this is a --no-argument */
    if (strlen (arg) > strlen (NEGATIVE_PREFIX) &&
	strncmp (arg, NEGATIVE_PREFIX, strlen (NEGATIVE_PREFIX)) == 0) {
	negative_arg = arg + strlen (NEGATIVE_PREFIX);
    }

    const notmuch_opt_desc_t *try;

    const char *next_arg = NULL;

    if (opt_index < argc - 1  && strncmp (argv[opt_index + 1], "--", 2) != 0)
	next_arg = argv[opt_index + 1];

    for (try = options; _opt_valid (try); try++) {
	if (try->opt_inherit) {
	    int new_index = parse_option (argc, argv, try->opt_inherit, opt_index);
	    if (new_index >= 0)
		return new_index;
	}

	if (! try->name)
	    continue;

	char next;
	const char *value;
	bool negate = false;

	if (strncmp (arg, try->name, strlen (try->name)) == 0) {
	    next = arg[strlen (try->name)];
	    value = arg + strlen (try->name) + 1;
	} else if (negative_arg && (try->opt_bool || try->opt_flags) &&
		   strncmp (negative_arg, try->name, strlen (try->name)) == 0) {
	    next = negative_arg[strlen (try->name)];
	    value = negative_arg + strlen (try->name) + 1;
	    /* The argument part of --no-argument matches, negate the result. */
	    negate = true;
	} else {
	    continue;
	}

	/*
	 * If we have not reached the end of the argument (i.e. the
	 * next character is not a space or delimiter) then the
	 * argument could still match a longer option name later in
	 * the option table.
	 */
	if (next != '=' && next != ':' && next != '\0')
	    continue;

	bool lookahead = (next == '\0' && next_arg != NULL && ! try->opt_bool);

	if (lookahead) {
	    next = ' ';
	    value = next_arg;
	    opt_index++;
	}

	opt_handled opt_status = OPT_FAILED;
	if (try->opt_keyword || try->opt_flags)
	    opt_status = _process_keyword_arg (try, next, value, negate);
	else if (try->opt_bool)
	    opt_status = _process_boolean_arg (try, next, value, negate);
	else if (try->opt_int)
	    opt_status = _process_int_arg (try, next, value);
	else if (try->opt_string)
	    opt_status = _process_string_arg (try, next, value);
	else
	    INTERNAL_ERROR ("unknown or unhandled option \"%s\"", try->name);

	if (opt_status == OPT_FAILED)
	    return -1;

	if (lookahead && opt_status == OPT_GIVEBACK)
	    opt_index--;

	if (try->present)
	    *try->present = true;

	return opt_index + 1;
    }
    return -1;
}

/* See command-line-arguments.h for description */
int
parse_arguments (int argc, char **argv,
		 const notmuch_opt_desc_t *options, int opt_index)
{

    int pos_arg_index = 0;
    bool more_args = true;

    while (more_args && opt_index < argc) {
	if (strncmp (argv[opt_index], "--", 2) != 0) {

	    more_args = parse_position_arg (argv[opt_index], pos_arg_index, options);

	    if (more_args) {
		pos_arg_index++;
		opt_index++;
	    }

	} else {
	    int prev_opt_index = opt_index;

	    if (strlen (argv[opt_index]) == 2)
		return opt_index + 1;

	    opt_index = parse_option (argc, argv, options, opt_index);
	    if (opt_index < 0) {
		fprintf (stderr, "Unrecognized option: %s\n", argv[prev_opt_index]);
		more_args = false;
	    }
	}
    }

    return opt_index;
}