import bpy
import os

def file_last_frame(scn):
    if scn.render.image_settings.file_format == 'H264':
        return "%s%04d-%04d.avi"%(scn.render.filepath, scn.frame_start, scn.frame_end)
    return "%s%04d.png"%(scn.render.filepath, scn.frame_end)

def string_for_blend_dependency():
    return bpy.data.filepath

def clause_for_scene(scn, tgt, tag = None):
    cmd = "blender -b %s -S '%s' -a\n\n"%(bpy.data.filepath, scn.name)
    if tag is None:
        rval = "%s: %s\n\t%s\n\n"%( tgt, string_for_blend_dependency(), cmd)
    else:
        l1 = ".INTERMEDIATE: %s.intermediate\n" % tag
        l2 = "%s: %s.intermediate\n" % (tgt, tag)
        l3 = "%s.intermediate: %s\n\t%s\n\n"%( tag, string_for_blend_dependency(), cmd)
        rval = l1+l2+l3
    return rval

def relativize(fname):
    if "/" == fname[0:1]:
        return fname
    else:
        return os.path.join(os.path.dirname(bpy.data.filepath), fname)

def single_output(scn):
    if scn.frame_start == scn.frame_end:
        return True

    if scn.render.image_settings.file_format == 'H264':
        return True

    return False


serial=0

def variables_for(scn):
    global serial
    if single_output(scn):
        serial = serial+1
        key="MOV%d"%serial
        fname = file_last_frame(scn)
        rval = key+" = "+fname+"\n"
        return ["$(%s)"%key , rval+"\n%s:$(%s)\n\n"%(key,key), key]
    else:
        serial=serial+1
        key = "PNGs%d"%serial
        rval = key+" ="
        for i in range(scn.frame_start, scn.frame_end+1):
            rval = rval + ( " %s%04d.png\\\n\t"%(scn.render.filepath, i))
        return [ "$(%s)"%key, rval+"\n%s: $(%s)\n\n" % (key, key), key ]


def write_makefile(ofname, all_target="all", scenes = None):

    if scenes is None:
        scenes = default_makefile_scenes()

    ofname = relativize(ofname)

    scene_rules = ""
    all_depends = ""
    variables = ""
    for scn in scenes:
        (target, v1, tag) = variables_for(scn)
        variables = variables + v1
        scene_rules = scene_rules + clause_for_scene(scn, target, tag)
        all_depends = all_depends + " " + target
    f = open(ofname, 'w')
    f.write(variables+"\n\n")
    f.write("#\n\n")
    f.write(scene_rules)
    f.write("#\n\n")
    f.write(all_target + ":" + all_depends+"\n\n")


def default_makefile_scenes():
    return [ scn for scn in bpy.data.scenes if scn.library is None]

def default_makefile_deps(basename = "blender.d"):
    import os
    return os.path.join(os.path.dirname(bpy.data.filepath), basename)


def cliche_makefile():
    ofname = default_makefile_deps()
    write_makefile(ofname, "pngs")

if __name__ == "__main__":
    overrides = bpy.data.texts.get('makefile overrides')
    if overrides is not None:
        # create a text buffer in your .blend file that replaces cliche_makefile() or default_makefile_scenes() or serial
        exec( overrides.as_string() )

    cliche_makefile()