__author__ = 'thoth'

import bpy


def extend_strip_to_match(strip):
    fr0 = None

    for fcurve in strip.action.fcurves:
        if len(fcurve.keyframe_points)<1:
            continue
        fr1 = fcurve.keyframe_points[0].co[0]
        if fr0 is None or fr1 <fr0:
            fr0 = fr1

    if fr0 is None:
        return

    if strip.action_frame_start > fr0:
        delta = strip.action_frame_start - fr0

        fs1 = strip.frame_start
        fe1 = strip.frame_end

        strip.action_frame_start = fr0
        strip.frame_start = fs1-delta
        strip.frame_end = fe1

def extend_nla_strips(action):
    for obj in bpy.data.shape_keys:
        if obj.animation_data is None:
            continue

        for track in obj.animation_data.nla_tracks:
            for strip in track.strips:
                if strip.action==action:
                    extend_strip_to_match(strip)

#
#

extend_nla_strips(bpy.data.actions['KeyAction'])