import pathlib
import sys
import wave

import bpy


def write_silence(path):
    path.parent.mkdir(parents=True, exist_ok=True)
    with wave.open(str(path), "wb") as stream:
        stream.setnchannels(1)
        stream.setsampwidth(2)
        stream.setframerate(8000)
        stream.writeframes(b"\0\0" * 8000)


def main(output_path):
    output = pathlib.Path(output_path).resolve()
    media = output.parent / "media"
    audio_path = media / "sequencer-silence.wav"
    image_path = media / "sequencer-frame.png"
    write_silence(audio_path)

    bpy.ops.wm.read_factory_settings(use_empty=True)
    image = bpy.data.images.new("SequencerFrame", width=8, height=8, alpha=True)
    image.generated_color = (0.2, 0.4, 0.8, 1.0)
    image.filepath_raw = str(image_path)
    image.file_format = "PNG"
    image.save()
    bpy.data.images.remove(image)

    scene = bpy.context.scene
    scene.name = "SequencerScene"
    scene.render.fps = 24
    scene.render.fps_base = 1.001
    editor = scene.sequence_editor_create()

    sound = editor.strips.new_sound("WebSound", str(audio_path), channel=1, frame_start=10)
    sound.mute = True
    sound.lock = True
    sound.sound.filepath = "//media/sequencer-silence.wav"

    image_strip = editor.strips.new_image("WebImage", str(image_path), channel=2, frame_start=12)
    image_strip.directory = "//media/"
    image_strip.elements[0].filename = "sequencer-frame.png"
    image_strip.frame_final_duration = 20

    second_image = editor.strips.new_image("WebImageB", str(image_path), channel=3, frame_start=12)
    second_image.directory = "//media/"
    second_image.elements[0].filename = "sequencer-frame.png"
    second_image.frame_final_duration = 20
    cross = editor.strips.new_effect(
        "WebCross", "CROSS", channel=4, frame_start=12, length=20, input1=image_strip, input2=second_image)
    cross.mute = True

    output.parent.mkdir(parents=True, exist_ok=True)
    bpy.ops.wm.save_as_mainfile(filepath=str(output), compress=False)
    print(f"sequencer-fixture-generated path={output} strips={len(editor.strips_all)}")


if __name__ == "__main__":
    arguments = sys.argv[sys.argv.index("--") + 1:]
    if len(arguments) != 1:
        raise SystemExit("usage: blender -b --python generate-sequencer-fixture.py -- output.blend")
    main(arguments[0])