xian_algorithm_new/app/services/qgis/template_cache.py

"""
模板缓存引擎。解决 QgsProject 单例问题。

流程：
1. 首次请求：project.read() 加载模板（慢，仅一次）
2. 加载后 project.write() 保存到临时文件
3. 后续同模板请求：从临时文件恢复（快，连接复用）
4. 手动恢复文本/过滤/缩放（毫秒级）
"""
import os
import time
import tempfile

from qgis.core import QgsProject, QgsRectangle

from app.config.paths import get_logger

logger = get_logger("qgis.cache")


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

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

    def load_template(self, template_path: str, layout_name: str = "A4") -> None:
        """首次加载模板"""
        start = time.time()
        project = QgsProject.instance()

        logger.info(f"首次加载: {os.path.basename(template_path)}")
        project.read(template_path)
        logger.info(f"project.read() 耗时: {time.time() - start:.1f}s")

        # 保存到临时文件
        tmp_file = tempfile.NamedTemporaryFile(
            suffix=".qgz", delete=False,
            dir=tempfile.gettempdir(),
        )
        tmp_path = tmp_file.name
        tmp_file.close()

        t_save = time.time()
        project.write(tmp_path)
        logger.info(f"项目保存耗时: {time.time() - t_save:.1f}s")

        # 记录初始状态
        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())

        self._cache[template_path] = {
            "file": tmp_path,
            "texts": texts,
            "extent": extent,
            "layout": layout_name,
        }
        logger.info(f"模板加载完成，总耗时: {time.time() - start:.1f}s")

    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}")

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

        logger.info(f"恢复模板: {os.path.basename(template_path)}")
        project.read(cached["file"])
        logger.info(f"project.read() 耗时: {time.time() - start:.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"""
        start = time.time()

        for layer in project.mapLayers().values():
            if layer.subsetString():
                layer.setSubsetString("")

        # 获取 layout 名称（从缓存中）
        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)

        logger.info(f"状态重置耗时: {time.time() - start:.3f}s")

    def cleanup(self) -> None:
        """清理所有临时文件"""
        for cached in self._cache.values():
            try:
                os.remove(cached["file"])
            except OSError:
                pass
        self._cache.clear()
        logger.info("已清理所有缓存")