using System.Diagnostics;
using System.Management;
using System.Runtime.InteropServices;

namespace StudioE5.SetupWizard;

public record PrerequisiteResult(
    bool WindowsCompatible,
    ulong RamMB,
    ulong FreeDiskMB,
    bool VirtualEnvironmentInstalled,
    bool PodmanInstalled,
    bool PodmanMachineReady)
{
    public bool AllReady => WindowsCompatible && RamMB >= 4096 && FreeDiskMB >= 5120 && VirtualEnvironmentInstalled && PodmanInstalled && PodmanMachineReady;
}

public static class PrerequisiteChecker
{
    public static PrerequisiteResult Check()
    {
        return new PrerequisiteResult(
            WindowsCompatible: IsWindowsCompatible(),
            RamMB: GetTotalPhysicalMemoryMB(),
            FreeDiskMB: GetFreeDiskSpaceMB("C:\\"),
            VirtualEnvironmentInstalled: IsWSLInstalled(),
            PodmanInstalled: IsPodmanInstalled(),
            PodmanMachineReady: IsPodmanMachineReady()
        );
    }

    private static bool IsWindowsCompatible()
    {
        var os = Environment.OSVersion;
        if (os.Platform != PlatformID.Win32NT)
            return false;

        // Windows 10 version 2004 (build 19041) or Windows 11.
        return Environment.OSVersion.Version.Build >= 19041;
    }

    private static ulong GetTotalPhysicalMemoryMB()
    {
        try
        {
            using var searcher = new ManagementObjectSearcher("SELECT TotalVisibleMemorySize FROM Win32_OperatingSystem");
            foreach (ManagementObject obj in searcher.Get())
            {
                var kb = Convert.ToUInt64(obj["TotalVisibleMemorySize"]);
                return kb / 1024;
            }
        }
        catch
        {
            // ignored
        }
        return 0;
    }

    private static ulong GetFreeDiskSpaceMB(string path)
    {
        try
        {
            var drive = new DriveInfo(Path.GetPathRoot(path) ?? path);
            return (ulong)(drive.AvailableFreeSpace / (1024 * 1024));
        }
        catch
        {
            return 0;
        }
    }

    private static bool IsWSLInstalled()
    {
        try
        {
            var psi = new ProcessStartInfo("wsl.exe", "--version")
            {
                UseShellExecute = false,
                CreateNoWindow = true,
                RedirectStandardOutput = true,
                RedirectStandardError = true
            };
            using var process = Process.Start(psi);
            if (process == null) return false;
            process.WaitForExit();
            return process.ExitCode == 0;
        }
        catch
        {
            return false;
        }
    }

    private static bool IsPodmanInstalled()
    {
        try
        {
            var psi = new ProcessStartInfo("podman.exe", "--version")
            {
                UseShellExecute = false,
                CreateNoWindow = true,
                RedirectStandardOutput = true,
                RedirectStandardError = true
            };
            using var process = Process.Start(psi);
            if (process == null) return false;
            process.WaitForExit();
            return process.ExitCode == 0;
        }
        catch
        {
            return false;
        }
    }

    private static bool IsPodmanMachineReady()
    {
        try
        {
            var psi = new ProcessStartInfo("podman.exe", "machine list --format json")
            {
                UseShellExecute = false,
                CreateNoWindow = true,
                RedirectStandardOutput = true,
                RedirectStandardError = true
            };
            using var process = Process.Start(psi);
            if (process == null) return false;
            var output = process.StandardOutput.ReadToEnd();
            process.WaitForExit();
            if (process.ExitCode != 0) return false;

            // Very permissive check: if podman machine list returns any JSON, we consider it ready.
            return output.TrimStart().StartsWith("[") || output.TrimStart().StartsWith("{");
        }
        catch
        {
            return false;
        }
    }
}