#include <xapian.h>
#include "notmuch-private.h"
#include "sexp.h"

typedef struct  {
    const char *name;
    Xapian::Query::op xapian_op;
    Xapian::Query initial;
} _sexp_op_t;

static _sexp_op_t operations[] =
{
    { "and",    Xapian::Query::OP_AND,          Xapian::Query::MatchAll },
    { "not",    Xapian::Query::OP_AND_NOT,      Xapian::Query::MatchAll },
    { "or",     Xapian::Query::OP_OR,           Xapian::Query::MatchNothing },
    { }
};

typedef struct  {
    const char *name;
    Xapian::Query::op xapian_op;
} _sexp_field_t;

static _sexp_field_t fields[] =
{
    { "subject",        Xapian::Query::OP_PHRASE },
    { }
};

static notmuch_status_t _sexp_to_xapian_query (notmuch_database_t *notmuch, const sexp_t *sx,
					       Xapian::Query &output);

static notmuch_status_t
_sexp_combine_query (notmuch_database_t *notmuch,
		     Xapian::Query::op operation,
		     Xapian::Query left,
		     const sexp_t *sx,
		     Xapian::Query &output)
{
    Xapian::Query subquery;

    notmuch_status_t status;

    /* if we run out elements, return accumulator */

    if (! sx) {
	output = left;
	return NOTMUCH_STATUS_SUCCESS;
    }

    status = _sexp_to_xapian_query (notmuch, sx, subquery);
    if (status)
	return status;

    return _sexp_combine_query (notmuch,
				operation,
				Xapian::Query (operation, left, subquery),
				sx->next, output);
}

notmuch_status_t
_notmuch_sexp_string_to_xapian_query (notmuch_database_t *notmuch, const char *querystr,
				      Xapian::Query &output)
{
    const sexp_t *sx = NULL;
    char *buf = talloc_strdup (notmuch, querystr);

    sx = parse_sexp (buf, strlen (querystr));
    if (! sx)
	return NOTMUCH_STATUS_BAD_QUERY_SYNTAX;

    return _sexp_to_xapian_query (notmuch, sx, output);
}

static void
_sexp_find_words (const char *str, std::string pref_str, std::vector<std::string> &terms)
{
    Xapian::Utf8Iterator p (str);
    Xapian::Utf8Iterator end;

    while (p != end) {
	Xapian::Utf8Iterator start;
	while (p != end && ! Xapian::Unicode::is_wordchar (*p))
	    p++;

	if (p == end)
	    break;

	start = p;

	while (p != end && Xapian::Unicode::is_wordchar (*p))
	    p++;

	if (p != start) {
	    std::string word (start, p);
	    word = Xapian::Unicode::tolower (word);
	    terms.push_back (pref_str + word);
	}
    }

}

static notmuch_status_t
_sexp_combine_field (const char *prefix,
		     Xapian::Query::op operation,
		     const sexp_t *sx,
		     Xapian::Query &output)
{
    std::vector<std::string> terms;

    for (const sexp_t *cur = sx; cur; cur = cur->next) {
	std::string pref_str = prefix;

	if (operation == Xapian::Query::OP_PHRASE) {
	    _sexp_find_words (cur->val, pref_str, terms);
	} else {
	    terms.push_back (pref_str + cur->val);
	}
    }
    output = Xapian::Query (operation, terms.begin (), terms.end ());
    return NOTMUCH_STATUS_SUCCESS;
}

/* Here we expect the s-expression to be a proper list, with first
 * element defining and operation, or as a special case the empty
 * list */

static notmuch_status_t
_sexp_to_xapian_query (notmuch_database_t *notmuch, const sexp_t *sx, Xapian::Query &output)
{

    const _sexp_op_t *op;

    /* Currently we don't understand atoms */
    assert (sx->ty == SEXP_LIST);

    /* Empty list */
    if (! sx->list) {
	output = Xapian::Query::MatchAll;
	return NOTMUCH_STATUS_SUCCESS;
    }

    for (op = operations; op && op->name; op++) {
	if (strcasecmp (op->name, hd_sexp (sx)->val) == 0) {
	    return _sexp_combine_query (notmuch, op->xapian_op, op->initial, sx->list->next, output);
	}
    }

    for (const _sexp_field_t *field = fields; field && field->name; field++) {
	if (strcasecmp (field->name, hd_sexp (sx)->val) == 0)
	    return _sexp_combine_field (_find_prefix (field->name), field->xapian_op, sx->list->next,
					output);
    }

    _notmuch_database_log_append (notmuch, "unimplemented prefix %s\n", sx->list->val);
    return NOTMUCH_STATUS_BAD_QUERY_SYNTAX;
}