import hashlib
import json
import os
import sys
import tempfile

import bpy


def layer_state(grease_pencil):
    return {
        "layerOrder": [layer.name for layer in grease_pencil.layers],
        "framesByLayer": {
            layer.name: sorted(frame.frame_number for frame in layer.frames)
            for layer in grease_pencil.layers
        },
    }


def main():
    arguments = sys.argv[sys.argv.index("--") + 1 :] if "--" in sys.argv else []
    if len(arguments) != 2:
        raise SystemExit("usage: blender -b fixture.blend --python generate-grease-pencil-reorder-golden.py -- fixture.blend output.json")
    fixture = os.path.abspath(arguments[0])
    output = os.path.abspath(arguments[1])
    grease_pencil = bpy.data.grease_pencils.get("GreasePencilData")
    if grease_pencil is None or len(grease_pencil.layers) != 1:
        raise RuntimeError("GreasePencilData fixture must contain exactly one source layer")

    source = layer_state(grease_pencil)
    layer = grease_pencil.layers.new("Web Drafts", set_active=True)
    layer.frames.new(1)
    before = layer_state(grease_pencil)
    grease_pencil.layers.move(layer, "DOWN")
    moved = layer.frames.move(1, 12)
    if moved is None:
        raise RuntimeError("Blender refused the Grease Pencil frame move")
    after = layer_state(grease_pencil)

    with tempfile.TemporaryDirectory(prefix="m9-08-grease-pencil-reorder-") as temporary:
        saved = os.path.join(temporary, "grease-pencil-reorder.blend")
        bpy.ops.wm.save_as_mainfile(filepath=saved, check_existing=False)
        bpy.ops.wm.open_mainfile(filepath=saved)
        reopened = layer_state(bpy.data.grease_pencils["GreasePencilData"])

    with open(fixture, "rb") as source_file:
        fixture_sha256 = hashlib.sha256(source_file.read()).hexdigest()
    payload = {
        "schemaVersion": 1,
        "fixture": "tests/files/web/modifier_grease_pencil_scene.blend",
        "fixtureSha256": fixture_sha256,
        "blenderVersion": ".".join(str(value) for value in bpy.app.version),
        "greasePencilName": "GreasePencilData",
        "source": source,
        "beforeReorder": before,
        "afterReorder": after,
        "reopened": reopened,
    }
    with open(output, "w", encoding="utf-8") as destination:
        json.dump(payload, destination, indent=2, sort_keys=True)
        destination.write("\n")


if __name__ == "__main__":
    main()