"""
模板缓存引擎（支持持久化）。

流程：
1. 首次加载：TemplateModifier 修改模板 → project.read() → 保存到磁盘缓存
2. 同进程内缓存命中：从内存恢复（~1s）
3. 跨进程/重启：从磁盘缓存恢复（首次 ~5s，后续 ~1s）
"""
import hashlib
import json
import os
import shutil
import time
import tempfile

from qgis.core import QgsProject, QgsRectangle

from app.config.paths import get_logger

logger = get_logger("qgis.cache")

# 持久化缓存目录（项目根目录下）
_CACHE_DIR = os.path.join(
    os.path.dirname(os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))),
    "app", "data", "cache", "qgis_templates",
)
_INDEX_FILE = os.path.join(_CACHE_DIR, "index.json")


class TemplateCache:
    def __init__(self):
        self._cache: dict[str, dict] = {}

    # ── 公开接口 ──

    def is_loaded(self, template_path: str) -> bool:
        return template_path in self._cache

    def save_current(self, template_path: str, layout_name: str = "A4") -> None:
        """将当前已加载的项目保存到内存缓存 + 磁盘缓存"""
        project = QgsProject.instance()

        # ── 保存项目到持久化缓存目录 ──
        os.makedirs(_CACHE_DIR, exist_ok=True)
        key = self._path_key(template_path)
        cache_file = os.path.join(_CACHE_DIR, f"{key}.qgz")

        t_save = time.time()
        project.write(cache_file)
        logger.info(f"  缓存写入磁盘: {os.path.basename(cache_file)} ({time.time() - t_save:.1f}s)")

        # ── 记录状态 ──
        texts = {}
        extent = None
        layout = project.layoutManager().layoutByName(layout_name)
        if layout:
            for item_id in ["mapTitle", "mapTime", "mapUint", "info"]:
                item = layout.itemById(item_id)
                if item:
                    texts[item_id] = item.text()
            map_item = layout.itemById("Map")
            if map_item:
                extent = QgsRectangle(map_item.extent())

        entry = {
            "file": cache_file,
            "texts": texts,
            "extent": extent,
            "layout": layout_name,
        }
        self._cache[template_path] = entry

        # ── 更新索引文件 ──
        self._update_index(template_path, entry)
        logger.info(f"  模板已缓存: {os.path.basename(template_path)} ({len(self._cache)} 个)")

    def restore_template(self, template_path: str) -> tuple:
        """从缓存恢复模板"""
        cached = self._cache.get(template_path)
        if not cached:
            raise RuntimeError(f"模板未缓存: {template_path}")

        project = QgsProject.instance()
        t0 = time.time()

        # 大部分图层已 GPKG 本地化，不需要 FlagDontResolveLayers
        project.read(cached["file"])

        logger.debug(f"  恢复耗时: {time.time() - t0:.1f}s")
        return project, cached["texts"], cached["extent"]

    def reset_project_state(self, project: QgsProject, texts: dict, extent) -> None:
        """重置项目到干净状态"""
        for layer in project.mapLayers().values():
            if layer.subsetString():
                layer.setSubsetString("")

        layout_name = "A4"
        for cached in self._cache.values():
            layout_name = cached.get("layout", "A4")
            break

        layout = project.layoutManager().layoutByName(layout_name)
        if layout:
            for item_id, text in texts.items():
                item = layout.itemById(item_id)
                if item:
                    item.setText(text)
            if extent:
                map_item = layout.itemById("Map")
                if map_item:
                    map_item.zoomToExtent(extent)

    def load_persistent_cache(self) -> int:
        """从磁盘恢复所有缓存到内存（qgis_runner 启动时调用）"""
        if not os.path.isfile(_INDEX_FILE):
            logger.info("  磁盘缓存为空，首次启动需要加载模板")
            return 0

        try:
            with open(_INDEX_FILE, "r", encoding="utf-8") as f:
                index = json.load(f)
        except (json.JSONDecodeError, OSError) as e:
            logger.warning(f"  缓存索引损坏: {e}")
            return 0

        count = 0
        for template_path, entry in index.get("templates", {}).items():
            cache_file = entry.get("file", "")
            if not cache_file or not os.path.isfile(cache_file):
                logger.debug(f"  跳过无效缓存: {os.path.basename(template_path)}")
                continue
            texts = entry.get("texts", {})
            extent = entry.get("extent")
            # 反序列化 extent
            if extent and isinstance(extent, dict):
                extent = QgsRectangle(
                    extent.get("xmin", 0), extent.get("ymin", 0),
                    extent.get("xmax", 0), extent.get("ymax", 0),
                )
            else:
                extent = None
            self._cache[template_path] = {
                "file": cache_file,
                "texts": texts,
                "extent": extent,
                "layout": entry.get("layout", "A4"),
            }
            count += 1

        logger.info(f"  磁盘缓存加载: {count} 个模板")
        return count

    def cleanup(self) -> None:
        """清理内存缓存（磁盘缓存保留）"""
        self._cache.clear()
        logger.info("已清理内存缓存")

    # ── 内部方法 ──

    @staticmethod
    def _path_key(template_path: str) -> str:
        """模板路径 → 缓存文件名 key"""
        return hashlib.md5(template_path.encode()).hexdigest()[:16]

    def _update_index(self, template_path: str, entry: dict) -> None:
        """更新磁盘索引文件"""
        index = {}
        if os.path.isfile(_INDEX_FILE):
            try:
                with open(_INDEX_FILE, "r", encoding="utf-8") as f:
                    index = json.load(f)
            except (json.JSONDecodeError, OSError):
                pass

        index.setdefault("templates", {})[template_path] = {
            "file": entry["file"],
            "layout": entry.get("layout", "A4"),
            "texts": entry.get("texts", {}),
            "extent": (
                {
                    "xmin": entry["extent"].xMinimum(),
                    "ymin": entry["extent"].yMinimum(),
                    "xmax": entry["extent"].xMaximum(),
                    "ymax": entry["extent"].yMaximum(),
                }
                if entry.get("extent") else None
            ),
        }

        with open(_INDEX_FILE, "w", encoding="utf-8") as f:
            json.dump(index, f, ensure_ascii=False, indent=2)