using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;

namespace Microsoft.Maui.Platform.Linux.Native;

internal static class WebKitNative
{
    private delegate IntPtr WebKitWebViewNewDelegate();
    private delegate void WebKitWebViewLoadUriDelegate(IntPtr webView, string uri);
    private delegate void WebKitWebViewLoadHtmlDelegate(IntPtr webView, string content, string? baseUri);
    private delegate IntPtr WebKitWebViewGetUriDelegate(IntPtr webView);
    private delegate IntPtr WebKitWebViewGetTitleDelegate(IntPtr webView);
    private delegate void WebKitWebViewGoBackDelegate(IntPtr webView);
    private delegate void WebKitWebViewGoForwardDelegate(IntPtr webView);
    private delegate bool WebKitWebViewCanGoBackDelegate(IntPtr webView);
    private delegate bool WebKitWebViewCanGoForwardDelegate(IntPtr webView);
    private delegate void WebKitWebViewReloadDelegate(IntPtr webView);
    private delegate void WebKitWebViewStopLoadingDelegate(IntPtr webView);
    private delegate IntPtr WebKitWebViewGetSettingsDelegate(IntPtr webView);
    private delegate void WebKitSettingsSetHardwareAccelerationPolicyDelegate(IntPtr settings, int policy);
    private delegate void WebKitSettingsSetEnableJavascriptDelegate(IntPtr settings, bool enabled);

    [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
    public delegate void LoadChangedCallback(IntPtr webView, int loadEvent, IntPtr userData);

    private delegate ulong GSignalConnectDataDelegate(IntPtr instance, string signalName, LoadChangedCallback callback, IntPtr userData, IntPtr destroyNotify, int connectFlags);

    public enum WebKitLoadEvent
    {
        Started,
        Redirected,
        Committed,
        Finished
    }

    private static IntPtr _handle;
    private static bool _initialized;

    private static readonly string[] LibraryNames = new string[4]
    {
        "libwebkit2gtk-4.1.so.0",
        "libwebkit2gtk-4.0.so.37",
        "libwebkit2gtk-4.0.so",
        "libwebkit2gtk-4.1.so"
    };

    private static WebKitWebViewNewDelegate? _webkitWebViewNew;
    private static WebKitWebViewLoadUriDelegate? _webkitLoadUri;
    private static WebKitWebViewLoadHtmlDelegate? _webkitLoadHtml;
    private static WebKitWebViewGetUriDelegate? _webkitGetUri;
    private static WebKitWebViewGetTitleDelegate? _webkitGetTitle;
    private static WebKitWebViewGoBackDelegate? _webkitGoBack;
    private static WebKitWebViewGoForwardDelegate? _webkitGoForward;
    private static WebKitWebViewCanGoBackDelegate? _webkitCanGoBack;
    private static WebKitWebViewCanGoForwardDelegate? _webkitCanGoForward;
    private static WebKitWebViewReloadDelegate? _webkitReload;
    private static WebKitWebViewStopLoadingDelegate? _webkitStopLoading;
    private static WebKitWebViewGetSettingsDelegate? _webkitGetSettings;
    private static WebKitSettingsSetHardwareAccelerationPolicyDelegate? _webkitSetHardwareAccel;
    private static WebKitSettingsSetEnableJavascriptDelegate? _webkitSetJavascript;
    private static GSignalConnectDataDelegate? _gSignalConnectData;

    private static readonly Dictionary<IntPtr, LoadChangedCallback> _loadChangedCallbacks = new Dictionary<IntPtr, LoadChangedCallback>();

    private const int RTLD_NOW = 2;
    private const int RTLD_GLOBAL = 256;

    private static IntPtr _gobjectHandle;

    [DllImport("libdl.so.2")]
    private static extern IntPtr dlopen(string? filename, int flags);

    [DllImport("libdl.so.2")]
    private static extern IntPtr dlsym(IntPtr handle, string symbol);

    [DllImport("libdl.so.2")]
    private static extern IntPtr dlerror();

    public static bool Initialize()
    {
        if (_initialized)
        {
            return _handle != IntPtr.Zero;
        }
        _initialized = true;

        string[] libraryNames = LibraryNames;
        foreach (string text in libraryNames)
        {
            _handle = dlopen(text, 258);
            if (_handle != IntPtr.Zero)
            {
                Console.WriteLine("[WebKitNative] Loaded " + text);
                break;
            }
        }

        if (_handle == IntPtr.Zero)
        {
            Console.WriteLine("[WebKitNative] Failed to load WebKitGTK library");
            return false;
        }

        _webkitWebViewNew = LoadFunction<WebKitWebViewNewDelegate>("webkit_web_view_new");
        _webkitLoadUri = LoadFunction<WebKitWebViewLoadUriDelegate>("webkit_web_view_load_uri");
        _webkitLoadHtml = LoadFunction<WebKitWebViewLoadHtmlDelegate>("webkit_web_view_load_html");
        _webkitGetUri = LoadFunction<WebKitWebViewGetUriDelegate>("webkit_web_view_get_uri");
        _webkitGetTitle = LoadFunction<WebKitWebViewGetTitleDelegate>("webkit_web_view_get_title");
        _webkitGoBack = LoadFunction<WebKitWebViewGoBackDelegate>("webkit_web_view_go_back");
        _webkitGoForward = LoadFunction<WebKitWebViewGoForwardDelegate>("webkit_web_view_go_forward");
        _webkitCanGoBack = LoadFunction<WebKitWebViewCanGoBackDelegate>("webkit_web_view_can_go_back");
        _webkitCanGoForward = LoadFunction<WebKitWebViewCanGoForwardDelegate>("webkit_web_view_can_go_forward");
        _webkitReload = LoadFunction<WebKitWebViewReloadDelegate>("webkit_web_view_reload");
        _webkitStopLoading = LoadFunction<WebKitWebViewStopLoadingDelegate>("webkit_web_view_stop_loading");
        _webkitGetSettings = LoadFunction<WebKitWebViewGetSettingsDelegate>("webkit_web_view_get_settings");
        _webkitSetHardwareAccel = LoadFunction<WebKitSettingsSetHardwareAccelerationPolicyDelegate>("webkit_settings_set_hardware_acceleration_policy");
        _webkitSetJavascript = LoadFunction<WebKitSettingsSetEnableJavascriptDelegate>("webkit_settings_set_enable_javascript");

        _gobjectHandle = dlopen("libgobject-2.0.so.0", 258);
        if (_gobjectHandle != IntPtr.Zero)
        {
            IntPtr intPtr = dlsym(_gobjectHandle, "g_signal_connect_data");
            if (intPtr != IntPtr.Zero)
            {
                _gSignalConnectData = Marshal.GetDelegateForFunctionPointer<GSignalConnectDataDelegate>(intPtr);
                Console.WriteLine("[WebKitNative] Loaded g_signal_connect_data");
            }
        }

        return _webkitWebViewNew != null;
    }

    private static T? LoadFunction<T>(string name) where T : Delegate
    {
        if (_handle == IntPtr.Zero)
        {
            return null;
        }
        IntPtr intPtr = dlsym(_handle, name);
        if (intPtr == IntPtr.Zero)
        {
            return null;
        }
        return Marshal.GetDelegateForFunctionPointer<T>(intPtr);
    }

    public static IntPtr WebViewNew()
    {
        if (!Initialize() || _webkitWebViewNew == null)
        {
            return IntPtr.Zero;
        }
        return _webkitWebViewNew();
    }

    public static void LoadUri(IntPtr webView, string uri)
    {
        _webkitLoadUri?.Invoke(webView, uri);
    }

    public static void LoadHtml(IntPtr webView, string content, string? baseUri = null)
    {
        _webkitLoadHtml?.Invoke(webView, content, baseUri);
    }

    public static string? GetUri(IntPtr webView)
    {
        IntPtr intPtr = _webkitGetUri?.Invoke(webView) ?? IntPtr.Zero;
        if (intPtr == IntPtr.Zero)
        {
            return null;
        }
        return Marshal.PtrToStringUTF8(intPtr);
    }

    public static string? GetTitle(IntPtr webView)
    {
        IntPtr intPtr = _webkitGetTitle?.Invoke(webView) ?? IntPtr.Zero;
        if (intPtr == IntPtr.Zero)
        {
            return null;
        }
        return Marshal.PtrToStringUTF8(intPtr);
    }

    public static void GoBack(IntPtr webView)
    {
        _webkitGoBack?.Invoke(webView);
    }

    public static void GoForward(IntPtr webView)
    {
        _webkitGoForward?.Invoke(webView);
    }

    public static bool CanGoBack(IntPtr webView)
    {
        return _webkitCanGoBack?.Invoke(webView) ?? false;
    }

    public static bool CanGoForward(IntPtr webView)
    {
        return _webkitCanGoForward?.Invoke(webView) ?? false;
    }

    public static void Reload(IntPtr webView)
    {
        _webkitReload?.Invoke(webView);
    }

    public static void StopLoading(IntPtr webView)
    {
        _webkitStopLoading?.Invoke(webView);
    }

    public static void ConfigureSettings(IntPtr webView, bool disableHardwareAccel = true)
    {
        if (_webkitGetSettings != null)
        {
            IntPtr intPtr = _webkitGetSettings(webView);
            if (intPtr != IntPtr.Zero && disableHardwareAccel && _webkitSetHardwareAccel != null)
            {
                _webkitSetHardwareAccel(intPtr, 2);
            }
        }
    }

    public static void SetJavascriptEnabled(IntPtr webView, bool enabled)
    {
        if (_webkitGetSettings != null && _webkitSetJavascript != null)
        {
            IntPtr intPtr = _webkitGetSettings(webView);
            if (intPtr != IntPtr.Zero)
            {
                _webkitSetJavascript(intPtr, enabled);
            }
        }
    }

    public static ulong ConnectLoadChanged(IntPtr webView, LoadChangedCallback callback)
    {
        if (_gSignalConnectData == null || webView == IntPtr.Zero)
        {
            Console.WriteLine("[WebKitNative] Cannot connect load-changed: signal connect not available");
            return 0uL;
        }
        _loadChangedCallbacks[webView] = callback;
        return _gSignalConnectData(webView, "load-changed", callback, IntPtr.Zero, IntPtr.Zero, 0);
    }

    public static void DisconnectLoadChanged(IntPtr webView)
    {
        _loadChangedCallbacks.Remove(webView);
    }
}