using System;
using System.Diagnostics;
using System.IO;
using System.Runtime.InteropServices;

namespace XP.Common.Helpers
{
    /// <summary>
    /// 进程管理工具类 | Process Management Helper
    /// 提供启动外部程序、窗口置前等通用功能 | Provides common functions like launching external programs and bringing windows to front
    /// </summary>
    public static class ProcessHelper
    {
        #region Win32 API

        [DllImport("user32.dll")]
        private static extern bool SetForegroundWindow(IntPtr hWnd);

        [DllImport("user32.dll")]
        private static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);

        [DllImport("user32.dll")]
        private static extern bool IsIconic(IntPtr hWnd);

        private const int SW_RESTORE = 9;

        #endregion

        /// <summary>
        /// 启动或激活外部程序 | Start or activate an external program
        /// </summary>
        /// <param name="exePath">可执行文件完整路径 | Full path to the executable</param>
        /// <param name="singleInstance">是否单实例模式：true=已运行则置前，false=直接启动新实例 | Single instance mode: true=activate if running, false=always start new instance</param>
        /// <returns>操作结果 | Operation result</returns>
        public static ProcessResult StartOrActivate(string exePath, bool singleInstance = true)
        {
            if (string.IsNullOrWhiteSpace(exePath))
            {
                return ProcessResult.Fail("程序路径未配置 | Program path not configured");
            }

            if (!File.Exists(exePath))
            {
                return ProcessResult.Fail($"程序文件不存在: {exePath} | Program file not found: {exePath}");
            }

            try
            {
                // 获取进程名（不含扩展名）| Get process name (without extension)
                var processName = Path.GetFileNameWithoutExtension(exePath);

                if (singleInstance)
                {
                    var processes = Process.GetProcessesByName(processName);

                    if (processes.Length > 0)
                    {
                        // 程序已运行，将窗口置前 | Program already running, bring window to front
                        var process = processes[0];
                        var hWnd = process.MainWindowHandle;

                        if (hWnd != IntPtr.Zero)
                        {
                            BringToFront(hWnd);
                        }

                        return ProcessResult.Activated();
                    }
                }

                // 启动程序 | Start program
                Process.Start(new ProcessStartInfo
                {
                    FileName = exePath,
                    UseShellExecute = true
                });

                return ProcessResult.Started();
            }
            catch (Exception ex)
            {
                return ProcessResult.Fail($"操作失败: {ex.Message} | Operation failed: {ex.Message}");
            }
        }

        /// <summary>
        /// 判断指定进程是否正在运行 | Check if a process is running
        /// </summary>
        /// <param name="processName">进程名（不含扩展名）| Process name (without extension)</param>
        /// <returns>是否运行中 | Whether the process is running</returns>
        public static bool IsProcessRunning(string processName)
        {
            return Process.GetProcessesByName(processName).Length > 0;
        }

        /// <summary>
        /// 根据可执行文件路径查找已运行的进程 | Find a running process by executable file path
        /// 通过进程名匹配并验证完整路径，确保找到的是同一个程序 | Matches by process name and verifies full path
        /// </summary>
        /// <param name="exePath">可执行文件完整路径 | Full path to the executable</param>
        /// <returns>找到的进程对象，未找到返回 null | The found process, or null if not found</returns>
        public static Process FindRunningProcess(string exePath)
        {
            if (string.IsNullOrWhiteSpace(exePath))
                return null;

            var processName = Path.GetFileNameWithoutExtension(exePath);
            var normalizedTarget = NormalizePath(exePath);

            try
            {
                var processes = Process.GetProcessesByName(processName);
                foreach (var proc in processes)
                {
                    try
                    {
                        // 验证完整路径匹配，避免同名不同路径的进程误关联
                        var procPath = proc.MainModule?.FileName;
                        if (procPath != null && string.Equals(NormalizePath(procPath), normalizedTarget, StringComparison.OrdinalIgnoreCase))
                        {
                            return proc;
                        }
                    }
                    catch
                    {
                        // 无法访问进程信息（权限不足等），跳过
                    }
                }
            }
            catch
            {
                // GetProcessesByName 异常，返回 null
            }

            return null;
        }

        /// <summary>
        /// 标准化文件路径，用于路径比较 | Normalize file path for comparison
        /// </summary>
        private static string NormalizePath(string path)
        {
            return Path.GetFullPath(path).TrimEnd(Path.DirectorySeparatorChar, Path.AltDirectorySeparatorChar);
        }

        /// <summary>
        /// 将窗口置前显示 | Bring a window to the foreground
        /// </summary>
        /// <param name="hWnd">窗口句柄 | Window handle</param>
        public static void BringToFront(IntPtr hWnd)
        {
            if (hWnd == IntPtr.Zero) return;

            // 如果窗口被最小化，先恢复 | If window is minimized, restore it first
            if (IsIconic(hWnd))
            {
                ShowWindow(hWnd, SW_RESTORE);
            }

            SetForegroundWindow(hWnd);
        }
    }

    /// <summary>
    /// 进程操作结果 | Process Operation Result
    /// </summary>
    public class ProcessResult
    {
        /// <summary>
        /// 是否成功 | Whether the operation succeeded
        /// </summary>
        public bool Success { get; private set; }

        /// <summary>
        /// 是否为新启动（false表示激活已有窗口）| Whether it was newly started (false means activated existing window)
        /// </summary>
        public bool IsNewlyStarted { get; private set; }

        /// <summary>
        /// 错误信息 | Error message
        /// </summary>
        public string ErrorMessage { get; private set; }

        /// <summary>
        /// 创建启动成功结果 | Create a started result
        /// </summary>
        public static ProcessResult Started() => new() { Success = true, IsNewlyStarted = true };

        /// <summary>
        /// 创建激活成功结果 | Create an activated result
        /// </summary>
        public static ProcessResult Activated() => new() { Success = true, IsNewlyStarted = false };

        /// <summary>
        /// 创建失败结果 | Create a failed result
        /// </summary>
        public static ProcessResult Fail(string errorMessage) => new() { Success = false, ErrorMessage = errorMessage };
    }
}