api

@contextlib.contextmanager
def comp_lock_and_undo_chunk(
    comp,
    undo_queue_name="Script CMD",
    keep_undo=True,
):
    """Lock comp and open an undo chunk during the context"""
    try:
        comp.Lock()
        comp.StartUndo(undo_queue_name)
        yield
    finally:
        comp.Unlock()
        comp.EndUndo(keep_undo)

def get_bmd_library():
    """Get bmd library"""
    bmd = getattr(sys.modules["__main__"], "bmd", None)
    return bmd

def get_current_comp():
    """Get current comp in this session"""
    fusion = get_fusion_module()
    if fusion is not None:
        comp = fusion.CurrentComp
        return comp

def imprint_container(tool,
                      name,
                      namespace,
                      context,
                      loader=None):
    """Imprint a Loader with metadata

    Containerisation enables a tracking of version, author and origin
    for loaded assets.

    Arguments:
        tool (object): The node in Fusion to imprint as container, usually a
            Loader.
        name (str): Name of resulting assembly
        namespace (str): Namespace under which to host container
        context (dict): Asset information
        loader (str, optional): Name of loader used to produce this container.

    Returns:
        None

    """

    data = [
        ("schema", "openpype:container-2.0"),
        ("id", AVALON_CONTAINER_ID),
        ("name", str(name)),
        ("namespace", str(namespace)),
        ("loader", str(loader)),
        ("representation", context["representation"]["id"]),
        ("project_name", context["project"]["name"]),
    ]

    for key, value in data:
        tool.SetData("avalon.{}".format(key), value)

def ls():
    """List containers from active Fusion scene

    This is the host-equivalent of api.ls(), but instead of listing
    assets on disk, it lists assets already loaded in Fusion; once loaded
    they are called 'containers'

    Yields:
        dict: container

    """

    comp = get_current_comp()
    tools = comp.GetToolList(False).values()

    for tool in tools:
        container = parse_container(tool)
        if container:
            yield container

@contextlib.contextmanager
def maintained_selection(comp=None):
    """Reset comp selection from before the context after the context"""
    if comp is None:
        comp = get_current_comp()

    previous_selection = comp.GetToolList(True).values()
    try:
        yield
    finally:
        flow = comp.CurrentFrame.FlowView
        flow.Select()  # No args equals clearing selection
        if previous_selection:
            for tool in previous_selection:
                flow.Select(tool, True)

def parse_container(tool):
    """Returns imprinted container data of a tool

    This reads the imprinted data from `imprint_container`.

    """

    data = tool.GetData('avalon')
    if not isinstance(data, dict):
        return

    # If not all required data return the empty container
    required = ['schema', 'id', 'name',
                'namespace', 'loader', 'representation']
    if not all(key in data for key in required):
        return

    container = {key: data[key] for key in required}

    # Add optional keys, like `project_name`
    optional = ["project_name"]
    for key in optional:
        if key in data:
            container[key] = data[key]

    # Store the tool's name
    container["objectName"] = tool.Name

    # Store reference to the tool object
    container["_tool"] = tool

    return container

def set_current_context_framerange(task_entity=None):
    """Set Comp's frame range based on current task."""
    if task_entity is None:
        task_entity = get_current_task_entity(
            fields={"attrib.frameStart",
                    "attrib.frameEnd",
                    "attrib.handleStart",
                    "attrib.handleEnd"})

    task_attributes = task_entity["attrib"]
    start = task_attributes["frameStart"]
    end = task_attributes["frameEnd"]
    handle_start = task_attributes["handleStart"]
    handle_end = task_attributes["handleEnd"]
    update_frame_range(start, end, set_render_range=True,
                       handle_start=handle_start,
                       handle_end=handle_end)

def update_frame_range(start, end, comp=None, set_render_range=True,
                       handle_start=0, handle_end=0):
    """Set Fusion comp's start and end frame range

    Args:
        start (float, int): start frame
        end (float, int): end frame
        comp (object, Optional): comp object from fusion
        set_render_range (bool, Optional): When True this will also set the
            composition's render start and end frame.
        handle_start (float, int, Optional): frame handles before start frame
        handle_end (float, int, Optional): frame handles after end frame

    Returns:
        None

    """

    if not comp:
        comp = get_current_comp()

    # Convert any potential none type to zero
    handle_start = handle_start or 0
    handle_end = handle_end or 0

    attrs = {
        "COMPN_GlobalStart": start - handle_start,
        "COMPN_GlobalEnd": end + handle_end
    }

    # set frame range
    if set_render_range:
        attrs.update({
            "COMPN_RenderStart": start,
            "COMPN_RenderEnd": end
        })

    with comp_lock_and_undo_chunk(comp):
        comp.SetAttrs(attrs)