#include <xapian.h>
#include "notmuch-private.h"
#include "sexp.h"
#include "parse-time-vrp.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[] =
{
    { "attachment",     Xapian::Query::OP_PHRASE },
    { "body",           Xapian::Query::OP_PHRASE },
    { "date",           Xapian::Query::OP_INVALID },
    { "from",           Xapian::Query::OP_PHRASE },
    { "folder",         Xapian::Query::OP_OR },
    { "id",             Xapian::Query::OP_OR },
    { "is",             Xapian::Query::OP_AND },
    { "mid",            Xapian::Query::OP_OR },
    { "mimetype",       Xapian::Query::OP_PHRASE },
    { "path",           Xapian::Query::OP_OR },
    { "property",       Xapian::Query::OP_AND },
    { "subject",        Xapian::Query::OP_PHRASE },
    { "tag",            Xapian::Query::OP_AND },
    { "thread",         Xapian::Query::OP_OR },
    { "to",             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;
}

static notmuch_status_t
_sexp_parse_date (notmuch_database_t *notmuch, const sexp_t *sx, Xapian::Query &output)
{
    std::string begin, end, msg;
    notmuch_status_t status;
    const sexp_t *cur = sx->list->next;

    if (cur) {
	begin = cur->val;
	cur = cur->next;
	if (cur) {
	    end = cur->val;
	    cur = cur->next;
	    if (cur) {
		_notmuch_database_log_append (notmuch, "extra argument(s) to date");
		return NOTMUCH_STATUS_BAD_QUERY_SYNTAX;
	    }
	    status = _notmuch_time_range_to_query (NOTMUCH_VALUE_TIMESTAMP, begin, end, msg, output);
	} else {
	    status = _notmuch_time_string_to_query (NOTMUCH_VALUE_TIMESTAMP, begin, msg, output);
	}
	if (status)
	    _notmuch_database_log_append (notmuch, "%s", msg.c_str ());
	return status;
    } else {
	_notmuch_database_log_append (notmuch, "missing argument(s) to date");
	return NOTMUCH_STATUS_BAD_QUERY_SYNTAX;
    }
}

/* 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;

    if (sx->ty == SEXP_VALUE) {
	Xapian::Query accumulator;
	for (const _sexp_field_t *field = fields; field && field->name; field++) {
	    std::vector<std::string> terms;
	    if (field->xapian_op == Xapian::Query::OP_INVALID)
		continue;
	    _sexp_find_words (sx->val, _find_prefix (field->name), terms);
	    accumulator = Xapian::Query (Xapian::Query::OP_OR, accumulator,
					 Xapian::Query (Xapian::Query::OP_PHRASE,
							terms.begin (), terms.end ()));
	}
	output = accumulator;
	return NOTMUCH_STATUS_SUCCESS;
    }
    /* 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) {
	    /* some fields need to be handled specially */
	    if (strcasecmp (field->name, "date") == 0) {
		return _sexp_parse_date (notmuch, sx, output);
	    }

	    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;
}