"""
QGIS 环境检测与子进程配置模块。

主进程运行在 Python 3.10，无法直接加载 QGIS 的 Python 3.12 C 扩展。
所有 QGIS 操作通过 subprocess 调用 QGIS Python 3.12 执行。

本模块提供：
  - get_qgis_python_path(): 检测 QGIS Python 3.12 解释器路径
  - build_qgis_command():   构建通过 .bat 启动 QGIS 子进程的命令
  - is_qgis_available():    检查 QGIS 是否可用
  - get_runner_script():    获取 qgis_runner.py 的路径
"""
import os
import tempfile
from pathlib import Path

from app.config.paths import get_logger

logger = get_logger("qgis.env")


def get_qgis_python_path(qgis_root: str = None) -> str | None:
    """
    检测 QGIS 自带的 Python 3.12 解释器路径。

    Windows: {QGIS_ROOT}/apps/Python312/python3.exe

    Returns:
        解释器绝对路径，不存在则返回 None
    """
    if qgis_root is None:
        qgis_root = _detect_qgis_root()
    if qgis_root is None:
        return None

    import platform
    if platform.system() == "Windows":
        for name in ("python3.exe", "python.exe"):
            candidate = os.path.join(qgis_root, "apps", "Python312", name)
            if os.path.isfile(candidate):
                logger.info(f"检测到 QGIS Python: {candidate}")
                return candidate
        logger.warning(f"未找到 QGIS Python 3.12")
        return None
    else:
        import shutil

        # 优先检查环境变量
        env_python = os.environ.get("QGIS_PYTHON_PATH")
        if env_python and os.path.isfile(env_python):
            logger.info(f"QGIS_PYTHON_PATH 指定: {env_python}")
            return env_python

        # 搜索标准 Linux QGIS 安装路径
        linux_paths = [
            "/usr/bin/qgis",  # Ubuntu/Debian apt 安装
            "/usr/bin/qgis.bin",
            "/opt/QGIS/apps/Python312/bin/python3",  # 独立安装器
            "/opt/QGIS/apps/Python3/bin/python3",
            "/usr/libexec/qgis/python3",  # Fedora/RHEL
        ]
        for candidate in linux_paths:
            if os.path.isfile(candidate):
                logger.info(f"检测到 QGIS 可执行文件: {candidate}")
                return candidate

        # 回退到系统 Python（如果 qgis.core 可导入）
        sys_python = shutil.which("python3") or shutil.which("python")
        if sys_python:
            logger.info(f"Linux 环境，使用系统 Python: {sys_python}")
            return sys_python
        return None


def build_qgis_command(qgis_root: str = None) -> list[str]:
    """
    构建通过 .bat 包装器启动 QGIS 子进程的命令列表。
    设置环境变量并启动 QGIS Python 3.12。
    """
    import platform
    if platform.system() != "Windows":
        python_path = get_qgis_python_path(qgis_root)
        if not python_path:
            raise RuntimeError("未找到 QGIS Python 解释器")
        return [python_path, get_runner_script()]

    if qgis_root is None:
        qgis_root = _detect_qgis_root() or "D:/QGIS"

    python_path = get_qgis_python_path(qgis_root)
    if not python_path:
        raise RuntimeError("未找到 QGIS Python 3.12 解释器")

    runner_script = get_runner_script()
    if not os.path.isfile(runner_script):
        raise RuntimeError(f"QGIS Runner 脚本不存在: {runner_script}")

    bat_path = _generate_bat_wrapper(qgis_root, python_path, runner_script)
    return ["cmd.exe", "/c", bat_path]


def is_qgis_available(qgis_root: str = None) -> bool:
    """检查 QGIS 环境是否可用"""
    return get_qgis_python_path(qgis_root) is not None


def get_runner_script() -> str:
    """获取 qgis_runner.py 的绝对路径"""
    return str(Path(__file__).parent / "qgis_runner.py")


def _generate_bat_wrapper(qgis_root: str, python_path: str, runner_script: str) -> str:
    """生成 .bat 包装脚本，设置 QGIS 环境变量并启动 runner"""
    qgis_app_dir = os.path.join(qgis_root, "apps", "qgis-ltr").replace("/", "\\")
    python_dir = os.path.join(qgis_root, "apps", "Python312").replace("/", "\\")
    qt5_plugins = os.path.join(qgis_root, "apps", "Qt5", "plugins").replace("/", "\\")
    qtplugins = os.path.join(qgis_app_dir, "qtplugins").replace("/", "\\")
    gdal_data = os.path.join(qgis_root, "apps", "gdal", "share", "gdal").replace("/", "\\")
    qgis_python_dir = os.path.join(qgis_app_dir, "python").replace("/", "\\")
    qgis_bin = os.path.join(qgis_app_dir, "bin").replace("/", "\\")
    qt5_bin = os.path.join(qgis_root, "apps", "Qt5", "bin").replace("/", "\\")
    gdal_lib = os.path.join(qgis_root, "apps", "gdal", "lib").replace("/", "\\")

    bat_content = f"""@echo off
set "PYTHONHOME={python_dir}"
set "PYTHONPATH={qgis_python_dir}"
set "QGIS_PREFIX_PATH={qgis_app_dir}"
set "QT_PLUGIN_PATH={qtplugins};{qt5_plugins}"
set "GDAL_DATA={gdal_data}"
set "PYTHONUTF8=1"
set "GDAL_FILENAME_IS_UTF8=YES"
set "VSI_CACHE=TRUE"
set "VSI_CACHE_SIZE=1000000"
set "PATH={qgis_bin};{qt5_bin};{gdal_lib};%PATH%"
"{python_path}" "{runner_script}" %*
"""

    bat_dir = os.path.join(tempfile.gettempdir(), "qgis_runner")
    os.makedirs(bat_dir, exist_ok=True)
    bat_path = os.path.join(bat_dir, "run_qgis.bat")
    with open(bat_path, "w", encoding="utf-8") as f:
        f.write(bat_content)
    logger.debug(f"生成 QGIS 包装脚本: {bat_path}")
    return bat_path


def _detect_qgis_root() -> str | None:
    """
    自动检测 QGIS 安装根目录。

    优先级：
    1. 环境变量 QGIS_ROOT
    2. Windows 默认路径 D:/QGIS
    3. Linux 常见路径
    """
    env_root = os.environ.get("QGIS_ROOT")
    if env_root and os.path.isdir(env_root):
        return env_root

    import platform
    if platform.system() == "Windows":
        for candidate in ["D:/QGIS", "C:/OSGeo4W", "C:/QGIS"]:
            if os.path.isdir(candidate):
                logger.info(f"检测到 QGIS 根目录: {candidate}")
                return candidate
    else:
        for candidate in ["/usr", "/opt/QGIS", "/home/QGIS"]:
            if os.path.isdir(candidate):
                logger.info(f"检测到 QGIS 根目录: {candidate}")
                return candidate

    logger.warning("未检测到 QGIS 安装目录")
    return None