添加AI图片功能

app/services/ai_image.py

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+"""AI 图片生成服务：后端请求 + 本地缓存管理。
+
+API 端点待接入，当前通过 ``set_api_caller`` 注入具体实现。
+缓存目录：``settings/ai_image_cache/``，每张图片有同名的 ``.json`` 侧车记录。
+"""
+
+from __future__ import annotations
+
+import datetime as _dt
+import hashlib
+import json
+import os
+import shutil
+import threading
+from dataclasses import dataclass, asdict
+from typing import Callable, List, Optional
+
+
+# ---------- 常量 ----------
+
+_CACHE_DIRNAME = os.path.join("settings", "ai_image_cache")
+_META_SUFFIX = ".json"
+_SUPPORTED_IMG_EXT = (".png", ".jpg", ".jpeg", ".bmp", ".webp")
+
+
+# ---------- 数据结构 ----------
+
+
+@dataclass
+class AIImageRecord:
+    """一条缓存记录。"""
+
+    id: str
+    prompt: str
+    image_path: str
+    created_at: str  # ISO8601
+    extra: Optional[dict] = None
+
+    def to_json(self) -> str:
+        return json.dumps(asdict(self), ensure_ascii=False, indent=2)
+
+
+# ---------- API 注入 ----------
+
+# 调用签名: ``fn(prompt: str) -> (image_bytes: bytes, image_ext: str, extra: dict|None)``
+# ``image_ext`` 例如 ``".png"``；``extra`` 可为 None。
+_ApiCaller = Callable[[str], tuple]
+
+_api_caller: Optional[_ApiCaller] = None
+
+
+def set_api_caller(fn: Optional[_ApiCaller]) -> None:
+    """注入真实的后端 API 调用函数。在 API 就绪前可保持为 None。"""
+    global _api_caller
+    _api_caller = fn
+
+
+def has_api() -> bool:
+    return _api_caller is not None
+
+
+# ---------- 缓存路径工具 ----------
+
+
+def get_cache_dir(base_dir: Optional[str] = None) -> str:
+    """返回缓存目录，如不存在则创建。``base_dir`` 默认使用当前工作目录。"""
+    root = base_dir if base_dir else os.getcwd()
+    path = os.path.join(root, _CACHE_DIRNAME)
+    os.makedirs(path, exist_ok=True)
+    return path
+
+
+def _make_id(prompt: str) -> str:
+    stamp = _dt.datetime.now().strftime("%Y%m%d_%H%M%S_%f")
+    digest = hashlib.md5(prompt.encode("utf-8")).hexdigest()[:8]
+    return f"{stamp}_{digest}"
+
+
+def _meta_path_for(image_path: str) -> str:
+    return os.path.splitext(image_path)[0] + _META_SUFFIX
+
+
+# ---------- 读写 ----------
+
+
+def list_records(base_dir: Optional[str] = None) -> List[AIImageRecord]:
+    """列出缓存目录下的所有记录，按创建时间倒序（最新在前）。"""
+    cache_dir = get_cache_dir(base_dir)
+    records: List[AIImageRecord] = []
+    for name in os.listdir(cache_dir):
+        full = os.path.join(cache_dir, name)
+        if not (os.path.isfile(full) and name.lower().endswith(_SUPPORTED_IMG_EXT)):
+            continue
+        meta_path = _meta_path_for(full)
+        prompt = ""
+        created_at = ""
+        extra = None
+        rec_id = os.path.splitext(name)[0]
+        if os.path.isfile(meta_path):
+            try:
+                with open(meta_path, "r", encoding="utf-8") as f:
+                    data = json.load(f)
+                prompt = data.get("prompt", "")
+                created_at = data.get("created_at", "")
+                extra = data.get("extra")
+                rec_id = data.get("id", rec_id)
+            except Exception:
+                pass
+        if not created_at:
+            # fallback 到文件 mtime
+            try:
+                mtime = os.path.getmtime(full)
+                created_at = _dt.datetime.fromtimestamp(mtime).isoformat()
+            except Exception:
+                created_at = ""
+        records.append(
+            AIImageRecord(
+                id=rec_id,
+                prompt=prompt,
+                image_path=full,
+                created_at=created_at,
+                extra=extra,
+            )
+        )
+    records.sort(key=lambda r: r.created_at, reverse=True)
+    return records
+
+
+def save_image_to_cache(
+    prompt: str,
+    image_bytes: bytes,
+    image_ext: str = ".png",
+    extra: Optional[dict] = None,
+    base_dir: Optional[str] = None,
+) -> AIImageRecord:
+    """把生成的图片字节写入缓存，返回记录。"""
+    if not image_ext.startswith("."):
+        image_ext = "." + image_ext
+    if image_ext.lower() not in _SUPPORTED_IMG_EXT:
+        image_ext = ".png"
+    cache_dir = get_cache_dir(base_dir)
+    rec_id = _make_id(prompt)
+    image_path = os.path.join(cache_dir, f"{rec_id}{image_ext}")
+    with open(image_path, "wb") as f:
+        f.write(image_bytes)
+
+    record = AIImageRecord(
+        id=rec_id,
+        prompt=prompt,
+        image_path=image_path,
+        created_at=_dt.datetime.now().isoformat(timespec="seconds"),
+        extra=extra,
+    )
+    try:
+        with open(_meta_path_for(image_path), "w", encoding="utf-8") as f:
+            f.write(record.to_json())
+    except Exception:
+        pass
+    return record
+
+
+def delete_record(record: AIImageRecord) -> bool:
+    """删除一条缓存记录（图片 + 侧车）。返回是否成功。"""
+    ok = True
+    for p in (record.image_path, _meta_path_for(record.image_path)):
+        try:
+            if os.path.isfile(p):
+                os.remove(p)
+        except Exception:
+            ok = False
+    return ok
+
+
+def export_record(record: AIImageRecord, dest_path: str) -> None:
+    """把缓存中的图片另存到 ``dest_path``。"""
+    shutil.copyfile(record.image_path, dest_path)
+
+
+# ---------- 异步请求 ----------
+
+
+def request_image_async(
+    prompt: str,
+    on_success: Callable[[AIImageRecord], None],
+    on_error: Callable[[Exception], None],
+    base_dir: Optional[str] = None,
+) -> threading.Thread:
+    """在后台线程请求 API → 写入缓存 → 回调。
+
+    ``on_success`` / ``on_error`` 会在 **工作线程** 中被调用；UI 侧若需
+    切回主线程，请在回调内部自行用 ``root.after(0, ...)``。
+    """
+
+    def _worker():
+        try:
+            if _api_caller is None:
+                raise RuntimeError("AI 图片 API 尚未接入，请调用 set_api_caller 注入")
+            image_bytes, image_ext, extra = _normalize_api_result(_api_caller(prompt))
+            record = save_image_to_cache(
+                prompt=prompt,
+                image_bytes=image_bytes,
+                image_ext=image_ext,
+                extra=extra,
+                base_dir=base_dir,
+            )
+            on_success(record)
+        except Exception as exc:
+            on_error(exc)
+
+    t = threading.Thread(target=_worker, daemon=True)
+    t.start()
+    return t
+
+
+def _normalize_api_result(result):
+    """允许 API 返回 ``bytes`` 或 ``(bytes, ext)`` 或 ``(bytes, ext, extra)``。"""
+    if isinstance(result, (bytes, bytearray)):
+        return bytes(result), ".png", None
+    if isinstance(result, tuple):
+        if len(result) == 2:
+            return bytes(result[0]), str(result[1]), None
+        if len(result) == 3:
+            return bytes(result[0]), str(result[1]), result[2]
+    raise ValueError("API 返回格式不支持，需为 bytes 或 (bytes, ext[, extra])")