SpineWallpaper/tools/downloader/selection.py

"""场景的选择：人写的 `sources.yml` 优先，其次机器写的 `selection.yml`，最后才问人。

为什么要第二份文件：`sources.yml` 是人手写的（注释、顺序、措辞都是人的），用 PyYAML 回写会把
这些全吃掉。所以机器只写自己那一份 `selection.yml`，人写的文件永远不被机器改写。

优先级（明确写死，避免两份文件打架）：

    1. `sources.yml` 里这一页写了 `scene:` / `spines:`   → 用它（人的意志最高）
    2. `selection.yml` 里有这一页的记录                 → 用它（上次交互的结果）
    3. 都没有                                           → 默认取骨架最多的场景 + 该场景全部骨架；
                                                          开了 `--interactive` 才问人

**这份选择不再裁剪产物**：`fetch` 会把页面里每个有资源的场景都落成一个壁纸目录（见
`tools/downloader/README.md`）。选择只决定"哪一档是推荐的"——写进 `page.json` 的
`chosenScene` / `chosenDir`，当 `promote` 没给 `--scene` 时的默认值。记录里的 `spines` /
`images` 字段保留只为兼容旧文件，不再有任何裁剪语义。
"""

from __future__ import annotations

from dataclasses import dataclass, field
from pathlib import Path
from typing import Any, Iterable, Sequence

import yaml

__all__ = ["Choice", "load_selection", "save_selection", "resolve", "ask"]

_HEADER = (
    "# 场景/骨架选择记录（由 `python -m tools.downloader select` 写入，机器所有）。\n"
    "# 人写的来源清单是 wallpapers/sources.yml；这里只记「哪一页推荐哪个场景」。\n"
    "# 入库是为了换台机器重跑能复现同一份推荐值。\n"
    "# 注意：fetch 会落盘**全部**有资源的场景，这份记录不再裁剪产物。\n"
    "# 优先级：sources.yml 的显式声明 > 本文件 > 默认值（骨架最多的场景）。\n"
)


@dataclass
class Choice:
    """一页的选择结果。"""

    page: str
    scene: str
    spines: list[str] = field(default_factory=list)
    source: str = "default"  # default | sources | selection | interactive
    images: list[str] = field(default_factory=list)

    def as_dict(self) -> dict[str, Any]:
        return {"scene": self.scene, "spines": list(self.spines), "images": list(self.images)}


def load_selection(path: Path) -> dict[str, Any]:
    if not path.exists():
        return {}
    data = yaml.safe_load(path.read_text(encoding="utf-8")) or {}
    return data if isinstance(data, dict) else {}


def save_selection(path: Path, selection: dict[str, Any]) -> None:
    path.parent.mkdir(parents=True, exist_ok=True)
    body = yaml.safe_dump(selection, allow_unicode=True, sort_keys=True, default_flow_style=False)
    path.write_text(_HEADER + body, encoding="utf-8")


def resolve(
    page: str,
    scenes: Sequence[Any],
    *,
    sources_entry: dict[str, Any] | None = None,
    selection: dict[str, Any] | None = None,
    default_scene: str | None = None,
    default_spines: Iterable[str] = (),
    interactive: bool = False,
    input_fn: Any = input,
    output_fn: Any = print,
) -> Choice:
    """按优先级算出一页要抓的场景与骨架。"""
    selection = selection or {}
    record = selection.get(page) or {}

    scene = None
    spines: list[str] = []
    source = "default"

    if sources_entry and sources_entry.get("scene"):
        scene = str(sources_entry["scene"])
        source = "sources"
    if sources_entry and sources_entry.get("spines"):
        spines = [str(s) for s in sources_entry["spines"]]
        source = "sources"

    if scene is None and record.get("scene"):
        scene = str(record["scene"])
        source = "selection"
    if not spines and record.get("spines"):
        spines = [str(s) for s in record["spines"]]
        if source == "default":
            source = "selection"

    if scene is None:
        scene = default_scene
    if not spines:
        spines = list(default_spines)

    # 记录里的场景若一个骨架都没有，它就是个**选不出壁纸**的记录（交互误选、或页面改版了）。
    # 这种情况退回默认并标明来源，别让人拿到一个必然报红的产物。
    if scenes and scene and scene != default_scene:
        chosen_scene = next((s for s in scenes if s.id == scene), None)
        if chosen_scene is not None and not chosen_scene.spine_ids and default_scene:
            source = f"{source}（无效→默认）"
            scene = default_scene
            spines = list(default_spines)

    if interactive and scenes:
        chosen = ask(page, scenes, scene=scene, spines=spines, input_fn=input_fn, output_fn=output_fn)
        if chosen is not None:
            scene, spines = chosen
            source = "interactive"

    return Choice(page=page, scene=scene or "", spines=spines, source=source)


def ask(
    page: str,
    scenes: Sequence[Any],
    *,
    scene: str | None,
    spines: Sequence[str],
    input_fn: Any = input,
    output_fn: Any = print,
) -> tuple[str, list[str]] | None:
    """交互式选择：只选**推荐场景**。

    为什么不再多选骨架：产物现在是"一个场景一个自包含的壁纸目录"，砍掉几具骨架会让这个场景的
    `sceneConfig` 缺件——那是坏壁纸，不是精简。要裁就在预设里裁（`preset.template.json` 是纯数据）。
    """
    output_fn(f"\n[{page}] 检测到 {len(scenes)} 个场景（**全部**会落盘，这里选的是推荐值）：")
    for i, s in enumerate(scenes, 1):
        mark = " ← 推荐" if s.id == scene else ""
        has_assets = any(p.kind in ("spine", "image") for p in s.parts)
        note = "" if has_assets else "（无资源，不会落盘）"
        output_fn(
            f"  {i}) {s.id}  骨架 {len(s.spine_ids)} 个，图片 "
            f"{sum(1 for p in s.parts if p.kind == 'image')} 个{note}{mark}"
        )
    raw = input_fn("推荐场景编号（回车取推荐值）：").strip()
    if raw:
        try:
            index = int(raw) - 1
            if not 0 <= index < len(scenes):
                output_fn("编号超出范围，取推荐值。")
            else:
                scene = scenes[index].id
        except ValueError:
            output_fn("不是数字，取推荐值。")

    target = next((s for s in scenes if s.id == scene), None)
    if target is None:
        return None
    if not any(p.kind in ("spine", "image") for p in target.parts):
        # 一件资源都没有的场景落不成壁纸（`fetch` 会跳过它）。与其让人推荐一个必然没有产物的
        # 场景，不如当场退回默认并说明原因。
        output_fn(f"[{page}] {scene} 里没有任何需要资源的 part，退回默认场景。")
        return None
    return scene, list(spines)