import ctypes
from ctypes import c_int, c_char_p, c_void_p
from cnotmuch.globals import nmlib, STATUS, NotmuchError


class Database(object):
    """ Wrapper around a notmuch_database_t

    Do note that as soon as we tear down this object, all derived queries,
    threads, and messages will be freed as well.
    """
    #constants
    MODE_READ_ONLY = 0
    MODE_READ_WRITE = 1

    _std_db_path = None
    """Class attribute of users default database"""

    """notmuch_database_get_path (notmuch_database_t *database)"""
    _get_path = nmlib.notmuch_database_get_path
    _get_path.restype = c_char_p

    """notmuch_database_open (const char *path, notmuch_database_mode_t mode)"""
    _open = nmlib.notmuch_database_open 
    _open.restype = c_void_p

    """notmuch_database_get_all_tags (notmuch_database_t *database)"""
    _get_all_tags = nmlib.notmuch_database_get_all_tags
    _get_all_tags.restype = c_void_p

    class notmuch_database_t(ctypes.Structure):
        """the opaque database that is returned by functions."""
        pass

    def __init__(self, path=None, create=False, status= MODE_READ_ONLY):
        """ Open or create a notmuch database"""
        self._db = None
        if create == False:
            self.open(path, status)
        else:
            #TODO: implement
            raise NotmuchError(message="Not implemented yet")

    #TODO: make a proper function
    create=nmlib.notmuch_database_create
    """ notmuch_database_create(const char *path):"""

    def open(self, path=None, status= MODE_READ_ONLY): 
        """calls notmuch_database_open

        If path is None, we will try to read a users notmuch configuration and
        use his default database.
        :returns: Raises :exc:`notmuch.NotmuchError` in case
                  of any failure (after printing an error message on stderr).
        """
        if path is None:
            if Database._std_db_path is None:
                from ConfigParser import SafeConfigParser
                import os.path
                config = SafeConfigParser()
                config.read(os.path.expanduser('~/.notmuch-config'))
                if not config.has_option('database','path'):
                    raise NotmuchError(message=
                              "No DB path specified and no user default found")
                Database._std_db_path=config.get('database','path')
            path = Database._std_db_path

        res = Database._open(path, status)

        if res is None:
            raise NotmuchError(
                message="Could not open the specified database")
        self._db = res

    def get_path(self):
        """notmuch_database_get_path (notmuch_database_t *database);  """
        return Database._get_path(self._db)

    #TODO:implement
    #If no message is found with the given message_id or if an
    #out-of-memory situation occurs, this function returns NULL.
    #notmuch_message_t *
    #notmuch_database_find_message (notmuch_database_t *database,
    #                               const char *message_id);

    def get_all_tags(self):
        """Return a Tags() object (list of all tags found in the database)

        :returns: Tags() object or raises :exc:`NotmuchError` with 
                  STATUS.NULL_POINTER on error
        """
        tags_p = Database._get_all_tags (self._db)
        if tags_p == None:
            raise NotmuchError(STATUS.NULL_POINTER)
        return Tags(tags_p, self)

    def __repr__(self):
        return "'Notmuch DB " + self.get_path() + "'"

    def __del__(self):
        """Close and free the notmuch database if needed"""
        if self._db is not None:
            print("Freeing the database now")
            nmlib.notmuch_database_close(self._db)

    @property
    def db_p(self):
        """Returns a pointer to the current notmuch_database_t or None"""
        return self._db


#------------------------------------------------------------------------------
class Tags(object):
    """Wrapper around notmuch_tags_t"""
    class notmuch_tags_t(ctypes.Structure):
        """the opaque tags struct that is returned by functions."""
        pass

    #notmuch_tags_get
    _get = nmlib.notmuch_tags_get
    _get.restype = c_char_p

    def __init__(self, tags_p, db=None):
        """ Is passed the db these tags are derived from, and saves a
        reference to it, so we can automatically delete the db object
        once all derived objects are dead.

        Tags() provides an iterator over all contained tags. However, you will
        only be able to iterate over the Tags once, because the underlying C
        function only allows iterating once.
        #TODO: make the iterator work more than once and cache the tags in 
               the Python object.
        """
        self._tags = tags_p
        self._db = db
        print "inited tags with %d %s" %(tags_p, str(db))
    
    def __iter__(self):
        """ Make Tags an iterator """
        return self

    def next(self):
        if self._tags is None:
            raise StopIteration
        nmlib.notmuch_tags_move_to_next(self._tags)
        if not nmlib.notmuch_tags_valid(self._tags):
            print("Freeing the Tags now")
            nmlib.notmuch_tags_destroy (self._tags)
            raise StopIteration
        return Tags._get (self._tags)

    def __del__(self):
        """Close and free the notmuch tags"""
        if self._tags is not None:
            print("Freeing the Tags now")
            nmlib.notmuch_tags_destroy (self._tags)