import lldb
import tempfile
import subprocess

def get_gst_parent(gst_obj):
    return gst_obj.GetChildMemberWithName("parent")

def get_gst_name(gst_obj):
    return gst_object.GetChildMemberWithName("name")

def get_gst_root(gst_obj):
    parent = get_gst_parent(gst_obj)
    while parent.GetValueAsUnsigned() != 0:
        gst_obj = parent
        parent = get_gst_parent(gst_obj)
    return gst_obj

def gst_dot(debugger, command, result, dict):
    error = lldb.SBError()

    gst_obj = lldb.frame.FindVariable(command).GetChildMemberWithName("object")
    root = get_gst_root(gst_obj)

    # FIXME: There must be a better way than EvaluateExpression
    #        to execute a function.
    GST_DEBUG_GRAPH_SHOW_ALL = "(GstDebugGraphDetails)15";
    dot_data = lldb.frame.EvaluateExpression(
        'gst_debug_bin_to_dot_data((GstBin*){}, {})'
        .format(
            root.GetValueAsUnsigned(),
            GST_DEBUG_GRAPH_SHOW_ALL))

    if dot_data.GetError().Fail():
        # Can happen if GStreamer is static and gst_debug_bin_to_dot_data is not referenced
        print dot_data.GetError().GetCString()
        return

    if dot_data.GetValueAsUnsigned() == 0:
        print "Error generating Graphviz data for {}".format(command)
        return

    dot_str = lldb.process.ReadCStringFromMemory(dot_data.GetValueAsUnsigned(), 0xffffff, error)
    if not error.Success:
        print "Error reading Graphviz data from memory!"
        return

    f = tempfile.NamedTemporaryFile(suffix = ".dot")
    f.write(dot_str)
    opener = "open"
    subprocess.call([opener, f.name])

def __lldb_init_module (debugger, dict):
    debugger.HandleCommand('command script add -f gst.gst_dot gst_dot')