using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
using Steamworks.Data;

namespace Steamworks
{
	/// <summary>
	/// Interface which provides access to a range of miscellaneous utility functions
	/// </summary>
	public class SteamUtils : SteamSharedClass<SteamUtils>
	{
		internal static ISteamUtils? Internal => Interface as ISteamUtils;

		internal override bool InitializeInterface( bool server )
		{
			SetInterface( server, new ISteamUtils( server ) );
			if ( Interface is null || Interface.Self == IntPtr.Zero ) return false;

			InstallEvents( server );

			return true;
		}

		internal static void InstallEvents( bool server )
		{
			Dispatch.Install<IPCountry_t>( x => OnIpCountryChanged?.Invoke(), server );
			Dispatch.Install<LowBatteryPower_t>( x => OnLowBatteryPower?.Invoke( x.MinutesBatteryLeft ), server );
			Dispatch.Install<SteamShutdown_t>( x => SteamClosed(), server );
			Dispatch.Install<GamepadTextInputDismissed_t>( x => OnGamepadTextInputDismissed?.Invoke( x.Submitted ), server );
		}

		private static void SteamClosed()
		{
			SteamClient.Cleanup();

			OnSteamShutdown?.Invoke();
		}

		/// <summary>
		/// Invoked when the country of the user changed.
		/// </summary>
		public static event Action? OnIpCountryChanged;

		/// <summary>
		/// Invoked when running on a laptop and less than 10 minutes of battery is left, fires then every minute.
		/// The parameter is the number of minutes left.
		/// </summary>
		public static event Action<int>? OnLowBatteryPower;

		/// <summary>
		/// Invoked when Steam wants to shutdown.
		/// </summary>
		public static event Action? OnSteamShutdown;

		/// <summary>
		/// Invoked when Big Picture gamepad text input has been closed. Parameter is <see langword="true"/> if text was submitted, <see langword="false"/> if cancelled etc.
		/// </summary>
		public static event Action<bool>? OnGamepadTextInputDismissed;

		/// <summary>
		/// Returns the number of seconds since the application was active.
		/// </summary>
		public static uint SecondsSinceAppActive => Internal?.GetSecondsSinceAppActive() ?? 0;

		/// <summary>
		/// Returns the number of seconds since the user last moved the mouse and/or provided other input.
		/// </summary>
		public static uint SecondsSinceComputerActive => Internal?.GetSecondsSinceComputerActive() ?? 0;

		// the universe this client is connecting to
		public static Universe ConnectedUniverse => Internal?.GetConnectedUniverse() ?? Universe.Invalid;

		/// <summary>
		/// Steam server time. Number of seconds since January 1, 1970, GMT (i.e unix time)
		/// </summary>
		public static DateTime SteamServerTime => Internal != null ? Epoch.ToDateTime( Internal.GetServerRealTime() ) : default;

		/// <summary>
		/// returns the 2 digit ISO 3166-1-alpha-2 format country code this client is running in (as looked up via an IP-to-location database)
		/// e.g "US" or "UK".
		/// </summary>
		public static string? IpCountry => Internal?.GetIPCountry();

		/// <summary>
		/// Returns true if the image exists, and the buffer was successfully filled out.
		/// Results are returned in RGBA format.
		/// The destination buffer size should be 4 * height * width * sizeof(char).
		/// </summary>
		public static bool GetImageSize( int image, out uint width, out uint height )
		{
			width = 0;
			height = 0;
			return Internal != null && Internal.GetImageSize( image, ref width, ref height );
		}

		/// <summary>
		/// returns the image in RGBA format.
		/// </summary>
		public static Data.Image? GetImage( int image )
		{
			if ( image == -1 ) return null;
			if ( image == 0 ) return null;

			var i = new Data.Image();

			if ( !GetImageSize( image, out i.Width, out i.Height ) )
				return null;

			var size = i.Width * i.Height * 4;

			var buf = Helpers.TakeBuffer( (int) size );

			if ( Internal is null || !Internal.GetImageRGBA( image, buf, (int)size ) )
				return null;

			i.Data = new byte[size];
			Array.Copy( buf, 0, i.Data, 0, size );
			return i;
		}

		/// <summary>
		/// Returns true if we're using a battery (ie, a laptop not plugged in).
		/// </summary>
		public static bool UsingBatteryPower => Internal != null && Internal.GetCurrentBatteryPower() != 255;

		/// <summary>
		/// Returns battery power [0-1].
		/// </summary>
		public static float CurrentBatteryPower => Math.Min( (Internal?.GetCurrentBatteryPower() ?? 0f) / 100, 1.0f );

		static NotificationPosition overlayNotificationPosition = NotificationPosition.BottomRight;

		/// <summary>
		/// Sets the position where the overlay instance for the currently calling game should show notifications.
		/// This position is per-game and if this function is called from outside of a game context it will do nothing.
		/// </summary>
		public static NotificationPosition OverlayNotificationPosition
		{
			get => overlayNotificationPosition;

			set
			{
				overlayNotificationPosition = value;
				Internal?.SetOverlayNotificationPosition( value );
			}
		}

		/// <summary>
		/// Returns true if the overlay is running and the user can access it. The overlay process could take a few seconds to
		/// start and hook the game process, so this function will initially return false while the overlay is loading.
		/// </summary>
		public static bool IsOverlayEnabled => Internal != null && Internal.IsOverlayEnabled();

		/// <summary>
		/// Normally this call is unneeded if your game has a constantly running frame loop that calls the 
		/// D3D Present API, or OGL SwapBuffers API every frame.
		///
		/// However, if you have a game that only refreshes the screen on an event driven basis then that can break 
		/// the overlay, as it uses your Present/SwapBuffers calls to drive it's internal frame loop and it may also
		/// need to Present() to the screen any time an even needing a notification happens or when the overlay is
		/// brought up over the game by a user.  You can use this API to ask the overlay if it currently need a present
		/// in that case, and then you can check for this periodically (roughly 33hz is desirable) and make sure you
		/// refresh the screen with Present or SwapBuffers to allow the overlay to do it's work.
		/// </summary>
		public static bool DoesOverlayNeedPresent => Internal != null && Internal.BOverlayNeedsPresent();

		/// <summary>
		/// Asynchronous call to check if an executable file has been signed using the public key set on the signing tab
		/// of the partner site, for example to refuse to load modified executable files.  
		/// </summary>
		public static async Task<CheckFileSignature> CheckFileSignatureAsync( string filename )
		{
			if (Internal is null) { throw new System.Exception( "SteamUtils not initialized" ); }
			
			var r = await Internal.CheckFileSignature( filename );

			if ( !r.HasValue )
			{
				throw new System.Exception( "Something went wrong" );
			}

			return r.Value.CheckFileSignature;
		}

		/// <summary>
		/// Activates the Big Picture text input dialog which only supports gamepad input.
		/// </summary>
		public static bool ShowGamepadTextInput( GamepadTextInputMode inputMode, GamepadTextInputLineMode lineInputMode, string description, int maxChars, string existingText = "" )
		{
			return Internal != null && Internal.ShowGamepadTextInput( inputMode, lineInputMode, description, (uint)maxChars, existingText );
		}

		/// <summary>
		/// Returns previously entered text.
		/// </summary>
		public static string GetEnteredGamepadText()
		{
			if (Internal is null) { return string.Empty; }
			
			var len = Internal.GetEnteredGamepadTextLength();
			if ( len == 0 ) return string.Empty;

			if ( !Internal.GetEnteredGamepadTextInput( out var strVal ) )
				return string.Empty;

			return strVal;
		}

		/// <summary>
		/// Returns the language the steam client is running in. You probably want 
		/// <see cref="SteamApps.GameLanguage"/> instead, this is for very special usage cases.
		/// </summary>
		public static string? SteamUILanguage => Internal?.GetSteamUILanguage();

		/// <summary>
		/// Returns <see langword="true"/> if Steam itself is running in VR mode.
		/// </summary>
		public static bool IsSteamRunningInVR => Internal != null && Internal.IsSteamRunningInVR();

		/// <summary>
		/// Sets the inset of the overlay notification from the corner specified by SetOverlayNotificationPosition.
		/// </summary>
		public static void SetOverlayNotificationInset( int x, int y )
		{
			Internal?.SetOverlayNotificationInset( x, y );
		}

		/// <summary>
		/// returns <see langword="true"/> if Steam and the Steam Overlay are running in Big Picture mode
		/// Games much be launched through the Steam client to enable the Big Picture overlay. During development,
		/// a game can be added as a non-steam game to the developers library to test this feature.
		/// </summary>
		public static bool IsSteamInBigPictureMode => Internal != null && Internal.IsSteamInBigPictureMode();


		/// <summary>
		/// Ask Steam UI to create and render its OpenVR dashboard.
		/// </summary>
		public static void StartVRDashboard() => Internal?.StartVRDashboard();

		/// <summary>
		/// Gets or sets whether the HMD content will be streamed via Steam In-Home Streaming.
		/// <para>
		/// If this is set to <see langword="true"/>, then the scene in the HMD headset will be streamed, and remote input will not be allowed.
		/// If this is set to <see langword="false"/>, then the application window will be streamed instead, and remote input will be allowed.
		/// The default is <see langword="true"/> unless "VRHeadsetStreaming" "0" is in the extended app info for a game
		/// (this is useful for games that have asymmetric multiplayer gameplay).
		/// </para>
		/// </summary>
		public static bool VrHeadsetStreaming
		{
			get => Internal != null && Internal.IsVRHeadsetStreamingEnabled();
			
			set
			{
				Internal?.SetVRHeadsetStreamingEnabled( value );
			}
		}

		internal static bool IsCallComplete( SteamAPICall_t call, out bool failed )
		{
			failed = false;
			return Internal != null && Internal.IsAPICallCompleted( call, ref failed );
		}


		/// <summary>
		/// Gets whether this steam client is a Steam China specific client (<see langword="true"/>), or the global client (<see langword="false"/>).
		/// </summary>
		public static bool IsSteamChinaLauncher => Internal != null && Internal.IsSteamChinaLauncher();

		/// <summary>
		/// Initializes text filtering, loading dictionaries for the language the game is running in.
		/// Users can customize the text filter behavior in their Steam Account preferences.
		/// </summary>
		public static bool InitFilterText() => Internal != null && Internal.InitFilterText( 0 );

		/// <summary>
		/// Filters the provided input message and places the filtered result into pchOutFilteredText,
		/// using legally required filtering and additional filtering based on the context and user settings.
		/// </summary>
		public static string FilterText( TextFilteringContext context, SteamId sourceSteamID, string inputMessage )
		{
			if ( Internal is null ) { return inputMessage; }
			Internal.FilterText( context, sourceSteamID, inputMessage, out var filteredString );
			return filteredString;
		}

		/// <summary>
		/// Gets whether or not Steam itself is running on the Steam Deck.
		/// </summary>
		public static bool IsRunningOnSteamDeck => Internal != null && Internal.IsSteamRunningOnSteamDeck();


		/// <summary>
		/// In game launchers that don't have controller support: You can call this to have 
		/// Steam Input translate the controller input into mouse/kb to navigate the launcher
		/// </summary>
		public static void SetGameLauncherMode( bool mode ) => Internal?.SetGameLauncherMode( mode );

		//public void ShowFloatingGamepadTextInput( TextInputMode mode, int left, int top, int width, int height )
		//{
		//	Internal.ShowFloatingGamepadTextInput( mode, left, top, width, height );
		//}
	}
}