Compressor/viewer/backend/services/scene_service.py

"""场景位置：data/scene_positions.csv 的读写（含初始种子）。

坐标存“参考系”（Z 不含随模型变化的 dz），前端应用时再叠加 dz。
"""

import csv
import os
from typing import Any

from config import DATA_DIR, SCENE_CSV

FIELDS = [
    "id", "name",
    "camera_x", "camera_y", "camera_z",
    "target_x", "target_y", "target_z",
]

# 初始种子：俯视 / 角度A（参考系坐标，与前端 VIEW_PRESETS 一致）。
SEED: list[tuple[int, str, list[float], list[float]]] = [
    (1, "俯视", [2.0, 22.0, -3.2], [2.0, 0.0, -22.0]),
    (2, "角度A", [5.4, 16.7, -6.3], [9.4, 0.0, -22.5]),
]


def _ensure_file() -> None:
    if SCENE_CSV.exists():
        return
    DATA_DIR.mkdir(parents=True, exist_ok=True)
    with SCENE_CSV.open("w", encoding="utf-8", newline="") as handle:
        writer = csv.writer(handle)
        writer.writerow(FIELDS)
        for scene_id, name, camera, target in SEED:
            writer.writerow([scene_id, name, *camera, *target])


def _to_scene(row: dict[str, str]) -> dict[str, Any]:
    return {
        "id": int(row["id"]),
        "name": row["name"],
        "camera": [float(row["camera_x"]), float(row["camera_y"]), float(row["camera_z"])],
        "target": [float(row["target_x"]), float(row["target_y"]), float(row["target_z"])],
    }


def _read() -> list[dict[str, Any]]:
    _ensure_file()
    with SCENE_CSV.open("r", encoding="utf-8", newline="") as handle:
        return [_to_scene(row) for row in csv.DictReader(handle)]


def _write(scenes: list[dict[str, Any]]) -> None:
    DATA_DIR.mkdir(parents=True, exist_ok=True)
    tmp = SCENE_CSV.parent / (SCENE_CSV.name + ".tmp")
    with tmp.open("w", encoding="utf-8", newline="") as handle:
        writer = csv.writer(handle)
        writer.writerow(FIELDS)
        for scene in scenes:
            writer.writerow([scene["id"], scene["name"], *scene["camera"], *scene["target"]])
    os.replace(tmp, SCENE_CSV)


def list_scenes() -> list[dict[str, Any]]:
    return _read()


def add_scene(name: str, camera: list[float], target: list[float]) -> dict[str, Any]:
    scenes = _read()
    scene = {
        "id": max((s["id"] for s in scenes), default=0) + 1,
        "name": name,
        "camera": [float(v) for v in camera],
        "target": [float(v) for v in target],
    }
    scenes.append(scene)
    _write(scenes)
    return scene


def rename_scene(scene_id: int, name: str) -> dict[str, Any] | None:
    scenes = _read()
    for scene in scenes:
        if scene["id"] == scene_id:
            scene["name"] = name
            _write(scenes)
            return scene
    return None


def delete_scene(scene_id: int) -> bool:
    scenes = _read()
    remaining = [scene for scene in scenes if scene["id"] != scene_id]
    if len(remaining) == len(scenes):
        return False
    _write(remaining)
    return True