#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;

typedef enum {
    SEXP_FLAG_NONE	= 0,
    SEXP_FLAG_WILDCARD	= 1 << 0,
} _sexp_flag_t;

/*
 * define bitwise operators to hide casts */

inline _sexp_flag_t
operator| (_sexp_flag_t a, _sexp_flag_t b)
{
    return static_cast<_sexp_flag_t>(
	static_cast<unsigned>(a) | static_cast<unsigned>(b));
}

inline _sexp_flag_t
operator& (_sexp_flag_t a, _sexp_flag_t b)
{
    return static_cast<_sexp_flag_t>(
	static_cast<unsigned>(a) & static_cast<unsigned>(b));
}

typedef struct  {
    const char *name;
    Xapian::Query::op xapian_op;
    _sexp_flag_t flags_allowed;
} _sexp_field_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 },
    { }
};

static _sexp_field_t fields[] =
{
    { "attachment",   Xapian::Query::OP_PHRASE,       SEXP_FLAG_WILDCARD },
    { "body",         Xapian::Query::OP_PHRASE,       SEXP_FLAG_WILDCARD },
    { "from",         Xapian::Query::OP_PHRASE,       SEXP_FLAG_NONE },
    { "folder",       Xapian::Query::OP_OR,           SEXP_FLAG_NONE },
    { "id",           Xapian::Query::OP_OR,           SEXP_FLAG_NONE },
    { "is",           Xapian::Query::OP_AND,          SEXP_FLAG_WILDCARD },
    { "mid",          Xapian::Query::OP_OR,           SEXP_FLAG_NONE },
    { "mimetype",     Xapian::Query::OP_PHRASE,       SEXP_FLAG_NONE },
    { "path",         Xapian::Query::OP_OR,           SEXP_FLAG_NONE },
    { "property",     Xapian::Query::OP_AND,          SEXP_FLAG_WILDCARD },
    { "subject",      Xapian::Query::OP_PHRASE,       SEXP_FLAG_NONE },
    { "tag",          Xapian::Query::OP_AND,          SEXP_FLAG_WILDCARD },
    { "thread",       Xapian::Query::OP_OR,           SEXP_FLAG_NONE },
    { "to",           Xapian::Query::OP_PHRASE,       SEXP_FLAG_NONE },
    { }
};

typedef struct {
    const char *name;
    _sexp_flag_t flag;
} _sexp_keyword_t;

static _sexp_keyword_t keywords[] =
{
    { "any", SEXP_FLAG_WILDCARD },
    { "*", SEXP_FLAG_WILDCARD },
    { }
};

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

static notmuch_status_t
_sexp_combine_query (notmuch_database_t *notmuch,
		     Xapian::Query::op operation,
		     Xapian::Query left,
		     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)
{
    sexp_t *sx = NULL;
    char *buf = talloc_strdup (notmuch, querystr);

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

    return _sexp_to_xapian_query (notmuch, sx, output);
}

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

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

	if (operation == Xapian::Query::OP_PHRASE) {
	    Xapian::Utf8Iterator p (cur->val);
	    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);
		}
	    }
	} 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_keywords (notmuch_database_t *notmuch, const char *prefix, sexp_t *sx, _sexp_flag_t mask,
		      _sexp_flag_t &flags, sexp_t *&rest)
{
    flags = SEXP_FLAG_NONE;

    for (; sx && sx->ty == SEXP_VALUE && sx->aty == SEXP_BASIC && sx->val[0] == ':'; sx = sx->next) {
	_sexp_keyword_t *keyword;
	for (keyword = keywords; keyword && keyword->name; keyword++) {
	    if (strcasecmp (keyword->name, sx->val+1) == 0) {
		if ((mask & keyword->flag) == 0) {
		    _notmuch_database_log_append (notmuch, "unsupported keyword '%s' for prefix '%s'\n",
						  sx->val, prefix);
		    return NOTMUCH_STATUS_ILLEGAL_ARGUMENT;
		} else {
		    flags = flags | keyword->flag;
		    break;
		}
	    }
	}
	if (! keyword || ! keyword->name) {
	    _notmuch_database_log (notmuch, "unknown keyword %s\n", sx->val);
	    return NOTMUCH_STATUS_ILLEGAL_ARGUMENT;
	}
    }

    rest = sx;
    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, 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) {
	    _sexp_flag_t flags;
	    sexp_t *rest;
	    const char *term_prefix;

	    notmuch_status_t status = _sexp_parse_keywords (notmuch, sx->list->val,
							    sx->list->next, field->flags_allowed,
							    flags, rest);
	    if (status)
		return status;

	    term_prefix = _find_prefix (field->name);

	    if (flags & SEXP_FLAG_WILDCARD) {
		output = Xapian::Query (Xapian::Query::OP_WILDCARD, term_prefix);
		return NOTMUCH_STATUS_SUCCESS;
	    } else {
		return _sexp_combine_field (term_prefix, field->xapian_op, rest,
					    output);
	    }
	}
    }

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