import json
import pathlib
import sys

import bpy


def main() -> None:
    if "--" not in sys.argv or len(sys.argv[sys.argv.index("--") + 1:]) != 3:
        raise SystemExit("usage: blender --background --python render-server-job.py -- SOURCE OUTPUT SETTINGS_JSON")
    source_arg, output_arg, settings_arg = sys.argv[sys.argv.index("--") + 1:]
    source = pathlib.Path(source_arg).resolve()
    output = pathlib.Path(output_arg).resolve()
    settings_path = pathlib.Path(settings_arg).resolve()
    if not source.is_file() or source.stat().st_size < 1:
        raise RuntimeError("server render source is missing")
    bpy.ops.wm.open_mainfile(filepath=str(source), load_ui=False)
    scene = bpy.context.scene
    if scene is None:
        raise RuntimeError("server render scene is missing")
    settings = json.loads(settings_path.read_text(encoding="utf-8"))
    engine = settings["renderEngine"]
    scene.render.engine = "BLENDER_EEVEE" if engine == "BLENDER_EEVEE_NEXT" else engine
    frame = int(settings["frameStart"])
    if frame != int(settings["frameEnd"]):
        raise RuntimeError("server render schema 1 requires a still frame")
    scene.render.resolution_x = int(settings["resolutionX"])
    scene.render.resolution_y = int(settings["resolutionY"])
    scene.render.resolution_percentage = int(settings["resolutionPercentage"])
    if scene.render.engine == "BLENDER_CYCLES":
        scene.cycles.samples = int(settings["samples"])
    elif scene.render.engine == "BLENDER_EEVEE":
        scene.eevee.taa_render_samples = int(settings["samples"])
    scene.render.image_settings.file_format = "PNG" if settings["outputMime"] == "image/png" else "OPEN_EXR"
    scene.render.film_transparent = bool(settings["transparent"])
    scene.frame_set(frame)
    scene.render.filepath = str(output)
    scene.render.use_file_extension = True
    bpy.ops.render.render(write_still=True)
    if not output.is_file() or output.stat().st_size < 1:
        raise RuntimeError("server render produced no output")
    print(f"server-render-ok frame={frame} output={output} bytes={output.stat().st_size}")


main()