#!/usr/bin/env python3
# SPDX-License-Identifier: GPL-2.0-or-later

# <pep8 compliant>

# This module can get render info without running from inside blender.
#
# This struct won't change according to Ton.
# Note that the size differs on 32/64bit
#
# typedef struct BHead {
#     int code, len;
#     void *old;
#     int SDNAnr, nr;
# } BHead;


def read_blend_rend_chunk(path):

    import struct

    blendfile = open(path, "rb")

    head = blendfile.read(7)

    if head[0:2] == b'\x1f\x8b':  # gzip magic
        import gzip
        blendfile.seek(0)
        blendfile = gzip.open(blendfile, "rb")
        head = blendfile.read(7)

    if head != b'BLENDER':
        print("not a blend file:", path)
        blendfile.close()
        return []

    is_64_bit = (blendfile.read(1) == b'-')

    # true for PPC, false for X86
    is_big_endian = (blendfile.read(1) == b'V')

    # Now read the bhead chunk!!!
    blendfile.read(3)  # skip the version

    scenes = []

    sizeof_bhead = 24 if is_64_bit else 20

    while blendfile.read(4) == b'REND':
        sizeof_bhead_left = sizeof_bhead - 4

        struct.unpack('>i' if is_big_endian else '<i', blendfile.read(4))[0]
        sizeof_bhead_left -= 4

        # We don't care about the rest of the bhead struct
        blendfile.read(sizeof_bhead_left)

        # Now we want the scene name, start and end frame. this is 32bites long
        start_frame, end_frame = struct.unpack('>2i' if is_big_endian else '<2i', blendfile.read(8))

        scene_name = blendfile.read(64)

        scene_name = scene_name[:scene_name.index(b'\0')]

        try:
            scene_name = str(scene_name, "utf8")
        except TypeError:
            pass

        scenes.append((start_frame, end_frame, scene_name))

    blendfile.close()

    return scenes


def main():
    import sys
    for arg in sys.argv[1:]:
        if arg.lower().endswith('.blend'):
            for value in read_blend_rend_chunk(arg):
                print("%d %d %s" % value)


if __name__ == '__main__':
    main()