Launching of simulation application

src/bedit_gui/services/simulation_files.py

@@ -0,0 +1,79 @@
+from __future__ import annotations
+
+import json
+import zlib
+from collections.abc import Mapping
+from pathlib import Path
+from typing import Any
+
+import msgpack
+
+from bedit_gui.simulation_models import SimulationRoot
+
+BES_MAGIC = b"BES\x00"
+FILE_FORMAT_VERSION = 1
+_VERSION_SIZE = 4
+
+
+def load(path: str | Path) -> SimulationRoot:
+    file_path = Path(path)
+    data = _load_json(file_path) if file_path.suffix.lower() == ".json" else _load_bes(file_path)
+    return SimulationRoot.from_data(data)
+
+
+def save(root: SimulationRoot, path: str | Path) -> None:
+    file_path = Path(path)
+    if file_path.suffix.lower() == ".json":
+        _save_json(root.to_data(), file_path)
+    elif file_path.suffix.lower() == ".bes":
+        _save_bes(root.to_data(), file_path)
+    else:
+        raise ValueError(f"unsupported simulation file extension {file_path.suffix!r}; expected '.json' or '.bes'")
+
+
+def is_simulation_json(path: str | Path) -> bool:
+    file_path = Path(path)
+    if file_path.suffix.lower() != ".json":
+        return False
+    try:
+        return _load_json(file_path).get("root_type") == "simulation_root"
+    except (TypeError, ValueError):
+        return False
+
+
+def _load_json(path: Path) -> Mapping[str, Any]:
+    try:
+        data = json.loads(path.read_text(encoding="utf-8"))
+    except (OSError, UnicodeError, json.JSONDecodeError) as exc:
+        raise ValueError(f"could not read simulation JSON {path}: {exc}") from exc
+    if not isinstance(data, Mapping):
+        raise TypeError(f"simulation JSON {path} must contain an object")
+    return data
+
+
+def _save_json(data: Mapping[str, Any], path: Path) -> None:
+    path.write_text(json.dumps({"file_format_version": FILE_FORMAT_VERSION, **data}, ensure_ascii=False, indent=2) + "\n", encoding="utf-8")
+
+
+def _load_bes(path: Path) -> Mapping[str, Any]:
+    try:
+        payload = path.read_bytes()
+        header_end = len(BES_MAGIC) + _VERSION_SIZE
+        if not payload.startswith(BES_MAGIC):
+            raise ValueError("missing BES file header")
+        if len(payload) < header_end:
+            raise ValueError("truncated BES file header")
+        version = int.from_bytes(payload[len(BES_MAGIC):header_end], "big")
+        if version != FILE_FORMAT_VERSION:
+            raise ValueError(f"unsupported BES file version {version}")
+        data = msgpack.unpackb(zlib.decompress(payload[header_end:]), raw=False, strict_map_key=False)
+    except (OSError, ValueError, zlib.error, msgpack.exceptions.MsgpackException) as exc:
+        raise ValueError(f"could not read BES simulation {path}: {exc}") from exc
+    if not isinstance(data, Mapping):
+        raise TypeError(f"BES simulation {path} must contain a map")
+    return data
+
+
+def _save_bes(data: Mapping[str, Any], path: Path) -> None:
+    encoded = zlib.compress(msgpack.packb(dict(data), use_bin_type=True))
+    path.write_bytes(BES_MAGIC + FILE_FORMAT_VERSION.to_bytes(_VERSION_SIZE, "big") + encoded)