from __future__ import annotations

import importlib.util
import os
import platform
import shutil
import sys
from typing import Any, Dict, List


def _has_module(module_name: str) -> bool:
    """安全检测 Python 模块是否可用"""
    try:
        return importlib.util.find_spec(module_name) is not None
    except ModuleNotFoundError:
        return False


def _get_lib_suffix() -> str:
    """获取当前平台的动态库后缀"""
    system = platform.system().lower()
    if system == "windows":
        return ".dll"
    elif system == "darwin":
        return ".dylib"
    return ".so"


def _check_ld_paths() -> List[str]:
    """检测动态库搜索路径"""
    paths = []
    for var in ["LD_LIBRARY_PATH", "DYLD_LIBRARY_PATH", "PATH"]:
        val = os.environ.get(var)
        if val:
            paths.extend([p for p in val.split(os.pathsep) if p])
    return paths[:10]  # 限制输出长度


def _cpp_runtime_available() -> bool:
    """检测 C++ 运行时能力（不依赖编译器）"""
    try:
        import ctypes  # noqa: F401
    except Exception:
        return False
    return platform.system().lower() in {"linux", "darwin", "windows"}


def collect_env_info() -> Dict[str, Any]:
    """收集完整的环境信息"""
    compilers = {
        "gcc": shutil.which("gcc"),
        "g++": shutil.which("g++"),
        "clang": shutil.which("clang"),
        "clang++": shutil.which("clang++"),
        "cl": shutil.which("cl"),  # MSVC
    }
    compile_available = any(compilers.values())
    runtime_available = _cpp_runtime_available()
    
    return {
        "python": {
            "version": sys.version.split()[0],
            "executable": sys.executable,
        },
        "platform": {
            "os": platform.system(),
            "release": platform.release(),
            "machine": platform.machine(),
            "lib_suffix": _get_lib_suffix(),
        },
        "matlab": {
            "engine_available": _has_module("matlab.engine") or _has_module("matlab"),
            "oct2py_available": _has_module("oct2py"),
            "octave_cli": shutil.which("octave") or shutil.which("octave-cli"),
        },
        "cpp": {
            "compilers": {k: v for k, v in compilers.items() if v},
            "compile_available": compile_available,
            "runtime_available": runtime_available,
            # Backward-compatible alias (historically used as "is cpp usable")
            "any_available": runtime_available,
        },
        "ld_paths": _check_ld_paths(),
        "scipy_available": _has_module("scipy"),
        "numpy_available": _has_module("numpy"),
        "web_available": _has_module("requests"),
    }


def get_available_algo_types() -> List[str]:
    """根据环境返回可用的算法类型列表"""
    env = collect_env_info()
    types = ["python"]  # Python 始终可用
    
    if env["matlab"]["engine_available"] or env["matlab"]["oct2py_available"] or env["matlab"]["octave_cli"]:
        types.append("matlab")
    
    # C++ 运行时可用即视为可执行（编译器仅影响“从源码编译”能力）
    if env["cpp"]["runtime_available"]:
        types.append("cpp")

    if env["web_available"]:
        types.append("web")
    
    return types


def check_endpoint_active(url: str, timeout: int = 5) -> Tuple[bool, str]:
    """检查远程端点是否存活"""
    try:
        import requests
        # 对根路径发起 GET 请求进行探活
        from urllib.parse import urljoin, urlparse
        parsed = urlparse(url)
        base_url = f"{parsed.scheme}://{parsed.netloc}"
        
        resp = requests.get(base_url, timeout=timeout)
        if resp.status_code < 500:
            return True, f"Active (HTTP {resp.status_code})"
        return False, f"Server Error (HTTP {resp.status_code})"
    except Exception as e:
        return False, f"Disconnected: {str(e)}"


def get_actionable_suggestions() -> List[Dict[str, str]]:
    """针对故障环境提供具体的修复指令建议"""
    env = collect_env_info()
    suggestions = []
    
    # MATLAB/Octave 建议
    if not (env["matlab"]["engine_available"] or env["matlab"]["oct2py_available"] or env["matlab"]["octave_cli"]):
        suggestions.append({
            "target": "MATLAB/Octave",
            "reason": "未检测到 MATLAB 引擎或 Octave 环境",
            "fix": "建议安装 Octave: `sudo apt install octave` 或安装相关 Python 库: `pip install oct2py`"
        })
    elif not env["matlab"]["engine_available"] and env["matlab"]["octave_cli"]:
        suggestions.append({
            "target": "MATLAB Engine",
            "reason": "当前使用 Octave 降级执行，性能可能受限",
            "fix": "若需原生性能，请安装 MATLAB 并运行 `cd \"$(matlabroot)/extern/engines/python\" && python setup.py install`"
        })

    # C++ 建议
    if not env["cpp"]["runtime_available"]:
        suggestions.append({
            "target": "C++ Runtime",
            "reason": "当前 Python 环境缺少 ctypes/动态链接支持",
            "fix": "请使用包含 ctypes 的标准 Python 发行版，或联系交付方提供兼容运行环境。",
        })
    elif not env["cpp"]["compile_available"]:
        suggestions.append({
            "target": "C++ Compiler",
            "reason": "未检测到 gcc/g++/clang 等编译器（仅影响“从源码编译”能力）",
            "fix": "建议安装基础构建工具: `sudo apt install build-essential`"
        })

    # 核心库建议
    if not env["scipy_available"]:
        suggestions.append({
            "target": "SciPy",
            "reason": "缺少 scipy 库，影响 MATLAB 兜底执行",
            "fix": "运行 `pip install scipy`"
        })

    return suggestions