#!/usr/bin/env python3
"""跨平台工具函数：设备检测和路径处理"""

import os
import sys
import platform
from pathlib import Path
from typing import Optional, Union

# 尝试导入torch，但不是强制的
try:
    import torch
    TORCH_AVAILABLE = True
except ImportError:
    TORCH_AVAILABLE = False
    torch = None


def get_platform_info() -> dict:
    """获取平台信息"""
    return {
        "system": platform.system(),
        "release": platform.release(),
        "version": platform.version(),
        "machine": platform.machine(),
        "processor": platform.processor(),
        "python_version": platform.python_version(),
        "python_executable": sys.executable,
        "current_dir": os.getcwd(),
    }


def is_windows() -> bool:
    """检查是否在Windows上运行"""
    return platform.system().lower() == "windows"


def is_linux() -> bool:
    """检查是否在Linux上运行"""
    return platform.system().lower() == "linux"


def is_macos() -> bool:
    """检查是否在macOS上运行"""
    return platform.system().lower() == "darwin"


def resolve_device(device: str = "auto", verbose: bool = True) -> str:
    """
    解析设备字符串，自动检测最佳设备

    Args:
        device: "auto", "cpu", "cuda", or "mps" (macOS)
        verbose: 是否打印信息

    Returns:
        设备字符串: "cpu", "cuda", or "mps"
    """
    if not TORCH_AVAILABLE:
        if verbose:
            print("警告: PyTorch未安装，只能使用CPU")
        return "cpu"

    device = device.lower().strip()

    if device == "cpu":
        if verbose:
            print("设备: CPU (用户指定)")
        return "cpu"

    if device == "cuda":
        if torch.cuda.is_available():
            if verbose:
                gpu_count = torch.cuda.device_count()
                gpu_name = torch.cuda.get_device_name(0) if gpu_count > 0 else "未知"
                print(f"设备: CUDA (GPU: {gpu_name}, 数量: {gpu_count})")
            return "cuda"
        else:
            if verbose:
                print("警告: 指定了CUDA但不可用，自动回退到CPU")
                print("提示: 检查PyTorch是否安装了GPU版本")
            return "cpu"

    if device == "mps" and is_macos():
        # macOS的Metal Performance Shaders
        if hasattr(torch.backends, 'mps') and torch.backends.mps.is_available():
            if verbose:
                print("设备: MPS (macOS Metal)")
            return "mps"
        else:
            if verbose:
                print("警告: MPS不可用，回退到CPU")
            return "cpu"

    # 自动检测
    if torch.cuda.is_available():
        if verbose:
            gpu_count = torch.cuda.device_count()
            gpu_name = torch.cuda.get_device_name(0) if gpu_count > 0 else "未知"
            print(f"设备: CUDA (自动检测到GPU: {gpu_name})")
        return "cuda"

    if is_macos() and hasattr(torch.backends, 'mps') and torch.backends.mps.is_available():
        if verbose:
            print("设备: MPS (macOS Metal, 自动检测)")
        return "mps"

    if verbose:
        print("设备: CPU (自动检测，无GPU可用)")
    return "cpu"


def safe_path(path: Union[str, Path]) -> str:
    """
    安全地处理路径，确保跨平台兼容性

    Args:
        path: 路径字符串或Path对象

    Returns:
        字符串形式的路径
    """
    if isinstance(path, Path):
        return str(path)

    # 如果是字符串，确保使用正确的路径分隔符
    path_str = str(path)

    # 替换可能存在的错误分隔符
    if is_windows():
        # Windows上，确保使用反斜杠
        path_str = path_str.replace('/', '\\')
    else:
        # Linux/macOS上，确保使用正斜杠
        path_str = path_str.replace('\\', '/')

    return path_str


def ensure_dir(path: Union[str, Path]) -> Path:
    """
    确保目录存在，如果不存在则创建

    Args:
        path: 目录路径

    Returns:
        Path对象
    """
    path_obj = Path(path) if isinstance(path, str) else path
    path_obj.mkdir(parents=True, exist_ok=True)
    return path_obj


def get_relative_path(base: Union[str, Path], target: Union[str, Path]) -> Path:
    """
    获取相对于基路径的相对路径

    Args:
        base: 基路径
        target: 目标路径

    Returns:
        相对路径的Path对象
    """
    base_path = Path(base) if isinstance(base, str) else base
    target_path = Path(target) if isinstance(target, str) else target

    # 如果目标路径是绝对路径，直接返回
    if target_path.is_absolute():
        return target_path

    # 否则相对于基路径
    return (base_path / target_path).resolve()


def resolve_path(base: Union[str, Path], target: Union[str, Path]) -> Path:
    """
    Resolve target path against base if target is relative.

    Args:
        base: base directory
        target: target path (absolute or relative)

    Returns:
        Absolute Path
    """
    base_path = Path(base) if isinstance(base, str) else base
    target_path = Path(target) if isinstance(target, str) else target
    if target_path.is_absolute():
        return target_path
    return (base_path / target_path).resolve()


def print_platform_summary():
    """打印平台摘要信息"""
    info = get_platform_info()
    print("=" * 50)
    print("平台信息:")
    print(f"  系统: {info['system']} {info['release']}")
    print(f"  处理器: {info['processor']}")
    print(f"  Python: {info['python_version']}")
    print(f"  当前目录: {info['current_dir']}")

    if TORCH_AVAILABLE:
        print(f"  PyTorch: {torch.__version__}")
        print(f"  CUDA可用: {torch.cuda.is_available()}")
        if torch.cuda.is_available():
            print(f"  GPU数量: {torch.cuda.device_count()}")
            for i in range(torch.cuda.device_count()):
                print(f"    GPU {i}: {torch.cuda.get_device_name(i)}")
    else:
        print("  PyTorch: 未安装")

    print("=" * 50)


if __name__ == "__main__":
    # 测试代码
    print_platform_summary()

    print("\n设备检测测试:")
    for device in ["auto", "cpu", "cuda", "mps"]:
        try:
            result = resolve_device(device, verbose=True)
            print(f"  输入: '{device}' -> 输出: '{result}'")
        except Exception as e:
            print(f"  输入: '{device}' -> 错误: {e}")

    print("\n路径处理测试:")
    test_path = "some/path/to/file.txt"
    print(f"  原始路径: {test_path}")
    print(f"  安全路径: {safe_path(test_path)}")