# Source code for canlib.kvadblib.dbc

    """Wrapper for Kvaser Database API (kvaDbLib).  For more info, see the kvaDbLib
       help files which are availible in the CANlib SDK.
       https://www.kvaser.com/developer/canlib-sdk/

    """

    import ctypes as ct

    from .message import Message
    from .node import Node
    from .attribute import Attribute
    from .attributedef import AttributeDefinition
    from .wrapper import dll

    from .enums import AttributeOwner, ProtocolType
    from .exceptions import KvdNoMessage, KvdNoNode, KvdNoAttribute, KvdOnlyOneAllowed, KvdWrongOwner

    DATABASE_FLAG_J1939 = 0x0001

    class Dbc(object):
        """Holds the root database handle."""
        def __init__(self, filename=None, name=None, protocol=None):
            """Create a new database.

            There are three ways to create a database:

            1. To load data from an existing database file, only set filename to
            the database filename.

            2. To add an empty database, set only name.

            3. To load data from an existing database file and give it a new name,
            set name to the new name and filename to the existing database filename.

            Either a name or a filename must be given.

            Args:
                filename (str, optional): The existing database file is read.
                name (str, optional): The database name will be set.

            """
            if name is None and filename is None:
                raise TypeError('Either a name or filename must to be given.')

            self._handle = None
            handle = ct.c_void_p(None)
            dll.kvaDbOpen(ct.byref(handle))
            self._handle = handle
            if name:
                name = name.encode('utf-8')
            if filename:
                filename = filename.encode('utf-8')
            dll.kvaDbCreate(self._handle, name, filename)

            # set default protocol to CAN
            if protocol is not None:
                self.protocol = protocol
            if protocol is None and self.protocol == ProtocolType.UNKNOWN:
                self.protocol = ProtocolType.CAN

        def __enter__(self):
            return self

        def __exit__(self, exc_type, exc_val, exc_tb):
            self.close()

        def __iter__(self):
            """Return a generator of all normal database messages.

                Equivalent to Dbc.messages(show_all=False).
            """

            return self.messages(show_all=False)

        def __len__(self):
            """Returns number of messages in database."""
            return sum(1 for _ in self)

        def __str__(self):
            return ("Dbc {}: flags:{}, protocol:{}, messages:{}".
                    format(self.name, self.flags, self.protocol.name, len(self)))

        def attribute_definitions(self):
            """Return a generator over all database attribute definitions."""
            adh = None
            nadh = ct.c_void_p()

            try:
                dll.kvaDbGetFirstAttributeDefinition(
                    self._handle, ct.byref(nadh))
            except KvdNoAttribute:
                return
            while nadh.value is not None:
                adh, nadh = nadh, ct.c_void_p()
                yield AttributeDefinition(self, adh)
                try:
                    dll.kvaDbGetNextAttributeDefinition(
                        adh, ct.byref(nadh))
                except KvdNoAttribute:
                    return
            return

        def attributes(self):
            """Return a generator over all database attributes.

            .. versionadded:: 1.6

            """
            ah = None
            nah = ct.c_void_p()
            try:
                dll.kvaDbGetFirstAttribute(self._handle, ct.byref(nah))
            except KvdNoAttribute:
                return
            while nah.value is not None:
                ah, nah = nah, ct.c_void_p()
                yield Attribute(self, ah)
                try:
                    dll.kvaDbGetNextAttribute(ah, ct.byref(nah))
                except KvdNoAttribute:
                    return

        def close(self):
            """Close an open database handle."""
            if self._handle:
                dll.kvaDbClose(self._handle)

        def delete_attribute(self, name):
            """Delete attribute from database.

            .. versionadded:: 1.6

            """
            ah = ct.c_void_p()
            dll.kvaDbGetAttributeByName(
                self._handle, name.encode('utf-8'), ct.byref(ah))
            dll.kvaDbDeleteAttribute(self._handle, ah)

        def delete_attribute_definition(self, name):
            """Delete attribute definition from database.

            .. versionadded:: 1.7

            """
            adh = ct.c_void_p(None)
            dll.kvaDbGetAttributeDefinitionByName(
                self._handle, name.encode('utf-8'), ct.byref(adh))
            dll.kvaDbDeleteAttributeDefinition(self._handle, adh)

        def delete_message(self, message):
            """Delete message from database.

            Args:
                message (:obj:`Message`): message to be deleted

            """
            dll.kvaDbDeleteMsg(self._handle, message._handle)

        def delete_node(self, node):
            """Delete node from database.

            Args:
                node (:obj:`Node`): node to be deleted

            """
            dll.kvaDbDeleteNode(self._handle, node._handle)

        def get_attribute_definition_by_name(self, name):
            """Find attribute definition using name.

            Args:
                name (str): name of attribute definition

            Returns an attribute definition object depending on type, e.g. if the
            type is AttributeType.INTEGER, an :obj:`IntegerAttributeDefinition` is
            returned.

            """
            adh = ct.c_void_p(None)
            dll.kvaDbGetAttributeDefinitionByName(
                self._handle, name.encode('utf-8'), ct.byref(adh))
            return AttributeDefinition(self, adh)

        def get_attribute_value(self, name):
            """Return attribute value

            If the attribute is not set on the database, we return the attribute
            definition default value.

            .. versionadded:: 1.6

            """
            ah = ct.c_void_p()

            # Try and find attribute on message
            try:
                dll.kvaDbGetAttributeByName(
                    self._handle, name.encode('utf-8'), ct.byref(ah))
            except KvdNoAttribute:
                # Lookup the attribute definition
                atr_def = self.get_attribute_definition_by_name(name)

                # only attributes with database as owner are valid, name is also
                # unique accross all attributes so it is enough to check this one
                # for owner
                if atr_def.owner != AttributeOwner.DB:
                    raise KvdWrongOwner()
                value = atr_def.definition.default
            else:
                attribute = Attribute(self, ah)
                value = attribute.value
            return value

        def get_message(self, id=None, name=None):
            """Find message by id or name

            If both id and name is given, both most match.

            Args:
                id (str): message id to look for
                name (str): message name to look for

            Returns:
                :obj:`Message`

            Raises:
                KvdNoMessage: If no match was found, or if none of `id` and
                    `name` were given.

            """
            message = None
            if (id is not None) and (name is not None):
                # Both arguments were given
                message = self.get_message_by_id(id)
                # attempts to search both for messages with and without EXT flag
                if message.name == name:
                    return message
                else:
                    raise KvdNoMessage()
            else:
                if id is not None:
                    return self.get_message_by_id(id)
                else:
                    return self.get_message_by_name(name)

        def get_message_by_id(self, id):
            """Find message by id

            Args:
                id (str): message id to look for

            Returns:
                :obj:`Message`

            Raises:
                KvdNoMessage: If no match was found.

            """
            mh = ct.c_void_p(None)
            dll.kvaDbGetMsgById(self._handle, id, ct.byref(mh))
            message = Message(db=self, handle=mh)
            return message

        def get_message_by_name(self, name):
            """Find message by name

            Args:
                name (str): message name to look for

            Returns:
                :obj:`Message`

            Raises:
                KvdNoMessage: If no match was found.

            """
            mh = ct.c_void_p(None)
            dll.kvaDbGetMsgByName(
                self._handle, name.encode('utf-8'), ct.byref(mh))
            message = Message(self, mh)
            return message

        def get_node_by_name(self, name):
            """Find node by name

            Args:
                name (str): node name to look for

            Returns:
                :obj:`Node`

            Raises:
                KvdNoNode: If no match was found.

            """
            nh = ct.c_void_p(None)
            dll.kvaDbGetNodeByName(
                self._handle, name.encode('utf-8'), ct.byref(nh))
            return Node(self, nh)

        def messages(self, show_all=True):
            """Return a generator of all database messages.

            If you would like to omit the special message
            'VECTOR__INDEPENDENT_SIG_MSG', which is used to collect removed signals
            under, set show_all to False or use the Dbc iterator directly::

                db = kvadblib.Dbc(filename='mydb.dbc')
                for message in db:
                    print(msg)

            Args:

                show_all (`bool`): If true, all messages, including any special
                    message such as 'VECTOR__INDEPENDENT_SIG_MSG' will be returned

            .. versionchanged:: 1.8
               Added argument show_all.

            """
            mh = ct.c_void_p(None)
            try:
                dll.kvaDbGetFirstMsg(self._handle, ct.byref(mh))
            except KvdNoMessage:
                return
            while mh.value is not None:
                msg = Message(self, mh)
                # The special message name VECTOR__INDEPENDENT_SIG_MSG is used in
                # .dbc files to collect unused signals into
                # Only return special message if show_all is True
                if show_all or msg.name != 'VECTOR__INDEPENDENT_SIG_MSG':
                    yield msg
                mh = ct.c_void_p()
                try:
                    dll.kvaDbGetNextMsg(self._handle, ct.byref(mh))
                except KvdNoMessage:
                    return

        def interpret(self, frame):
            """Interprets a given Frame object, returning a BoundMessage"""
            message = self.get_message_by_id(frame.id)
            return message.bind(frame)

        def new_attribute_definition(self, name, owner, type, definition):
            """Create a new attribute definition in the database.

            The owner specify where the attribute is applicable,
            e.g. :obj:`AttributeOwner.MESSAGE` specifies that this attribute is
            only applicable on messages (:obj:`Message`).

            Args:
                name (str): a unique name.
                owner (:obj:`AttributeOwner`): the owner type

            Returns:
                :obj:`AttributeDefinition`

            """
            adh = ct.c_void_p(None)
            dll.kvaDbAddAttributeDefinition(self._handle, ct.byref(adh))
            dll.kvaDbSetAttributeDefinitionType(adh, type.value)
            dll.kvaDbSetAttributeDefinitionName(adh, name.encode('utf-8'))
            dll.kvaDbSetAttributeDefinitionOwner(adh, owner)

            atr_def = AttributeDefinition(self, adh, definition)
            return atr_def

        def new_message(self, name, id, flags=0, dlc=None, comment=None):
            """Create a new message in the database.

            Args:
                name (str): name of message
                id (int): message id
                flags (int, optional): message flags, e.g. MESSAGE_EXT

            Returns:
                :obj:`canlib.kvadblib.message.Message`

            """
            mh = ct.c_void_p(None)
            dll.kvaDbAddMsg(self._handle, ct.byref(mh))
            try:
                message = Message(self, mh, name, id, flags, dlc, comment)
            except KvdOnlyOneAllowed:
                # If KvdOnlyOneAllowed is thrown, the message was created but not
                # named properly, in which case we need to delete the message
                # before calling the users attention
                dll.kvaDbDeleteMsg(self._handle, mh)
                raise
            return message

        def new_node(self, name, comment=None):
            """Create a new node in the database.

            Args:
                name (str): name of message
                comment (str, optional): message comment

            Returns:
                :obj:`Node`

            """
            nh = ct.c_void_p(None)
            dll.kvaDbAddNode(self._handle, ct.byref(nh))
            try:
                node = Node(self, nh, name, comment)
            except KvdOnlyOneAllowed:
                # If KvdOnlyOneAllowed is thrown, the node was created but not
                # named properly, in which case we need to delete the node
                # before calling the users attention
                dll.kvaDbDeleteNode(self._handle, nh)
                raise
            return node

        def node_in_signal(self, node, signal):
            """Check if signal has been added to node.

            Returns:
                True:  signals contains node
                False: otherwise
            """
            try:
                dll.kvaDbSignalContainsReceiveNode(signal._handle, node._handle)
            except KvdNoNode:
                return False
            return True

        def nodes(self):
            """Return a generator containing all database nodes."""
            nh = ct.c_void_p(None)
            try:
                dll.kvaDbGetFirstNode(self._handle, ct.byref(nh))
            except KvdNoNode:
                return
            while nh.value is not None:
                yield Node(self, nh)
                nh = ct.c_void_p()
                try:
                    dll.kvaDbGetNextNode(self._handle, ct.byref(nh))
                except KvdNoNode:
                    return

        def set_attribute_value(self, name, value):
            """Set value of attribute 'name' on database.

            If no attribute called 'name' is set on database, attach a database
            attribute from the database attribute definition first.

            .. versionadded:: 1.6

            """
            ah = ct.c_void_p()

            # Try and find attribute on database
            try:
                dll.kvaDbGetAttributeByName(
                    self._handle, name.encode('utf-8'), ct.byref(ah))
            except KvdNoAttribute:
                # If no attribute was found, lookup the attribute definition and
                # add a new attribute to the message
                attrib_def = self.get_attribute_definition_by_name(name)
                dll.kvaDbAddAttribute(
                    self._handle, attrib_def._handle, ct.byref(ah))
            # Set the value in the message attribute
            attribute = Attribute(self, ah)
            attribute.value = value

        def write_file(self, filename):
            """Write a database to file.

            Args:
                filename (str): file to write database to

            """
            dll.kvaDbWriteFile(self._handle, filename.encode('utf-8'))

        @property
        def flags(self):
            """Get the database flags.

            E.g. DATABASE_FLAG_J1939
            """
            flags = ct.c_uint()
            dll.kvaDbGetFlags(self._handle, ct.byref(flags))
            return flags.value

        @flags.setter
        def flags(self, value):
            """Set the database flags.

            E.g. DATABASE_FLAG_J1939
            """
            dll.kvaDbSetFlags(self._handle, value)

        @property
        def name(self):
            """`str`: The current database name (read-only)"""
            buf = ct.create_string_buffer(255)
            dll.kvaDbGetDatabaseName(self._handle, buf, ct.sizeof(buf))
            return buf.value.decode('utf-8')

        @property
        def protocol(self):
            """`ProtocolType`: The database protocol"""
            p = ct.c_int()
            dll.kvaDbGetProtocol(self._handle, ct.byref(p))
            return ProtocolType(p.value)

        @protocol.setter
        def protocol(self, value):
            dll.kvaDbSetProtocol(self._handle, value)