#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 Xapian::Query _sexp_to_xapian_query (sexp_t *sx);

static Xapian::Query
_sexp_combine_query (Xapian::Query::op operation,
		     Xapian::Query left,
		     sexp_t *sx)
{

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

    if (! sx)
	return left;

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

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

    sx = parse_sexp (buf, strlen (querystr));
    return _sexp_to_xapian_query (sx);
}

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

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

	if (operation == Xapian::Query::OP_PHRASE)
	    word = Xapian::Unicode::tolower (word);


	terms.push_back (pref_str + word);
    }
    return Xapian::Query (operation, terms.begin (), terms.end ());
}

/* 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 Xapian::Query
_sexp_to_xapian_query (sexp_t *sx)
{

    const _sexp_op_t *op;

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

    /* Empty list */
    if (! sx->list)
	return Xapian::Query::MatchAll;

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

    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);
    }

    INTERNAL_ERROR ("unimplemented prefix %s\n", sx->list->val);
}