////////////////////////////////////////////////////////////////////////////////
//
//  Microsoft Research Singularity
//
//  Copyright (c) Microsoft Corporation.  All rights reserved.
//
//  File:   Pong.cs
//
//  Note:
//

using System;
using System.Text;
using System.GC;
using System.Runtime.Remoting;
using System.Runtime.InteropServices;
using System.Runtime.CompilerServices;
using System.Threading;
using System.Collections;
using System.Diagnostics;

using Microsoft.Singularity;
using Microsoft.Singularity.Directory;
using Microsoft.Singularity.V1.Services;
using Microsoft.Singularity.Io;

using Microsoft.Singularity.Channels;
using Keyboard = Microsoft.Singularity.Io.Keyboard;

namespace Microsoft.Singularity.Applications
{
    public class Pong
    {
        const uint Black    = 0x000000;
        const uint Blue     = 0x0000ff;
        const uint Green    = 0x00ff00;
        const uint Red      = 0xff0000;
        const uint White    = 0xffffff;

        const int screenWidth = 1024;
        const int screenHeight = 768;

        const int paddleWidth = 16;
        const int paddleHeight = 128;

        const int ballSize = 8;

        const double paddleSpeed = 0.20;
        const double ballSpeed = 0.35;

        const double ballStartAngle = Math.PI / 8;
        const double ballMaxAngle = Math.PI / 3;

        const int screenMinX = 0;
        const int screenMinY = 0;

        const int screenMaxX = screenMinX + screenWidth - 1;
        const int screenMaxY = screenMinY + screenHeight - 1;

        const int paddleMin = screenMinY;
        const int paddleMax = screenMaxY - paddleHeight;

        const int ballMinX = screenMinX + paddleWidth;
        const int ballMaxX = screenMaxX - paddleWidth - ballSize;

        const int ballMinY = screenMinY;
        const int ballMaxY = screenMaxY - ballSize;

        const int paddleInit = screenMinY + ((screenHeight - paddleHeight) / 2);

        static double ballX = 0.0;
        static double ballY = 0.0;
        static double ballAngle = 0.0;

        static int ballDrawX = 0;
        static int ballDrawY = 0;

        static double[] paddlesY = new double [2] { paddleInit, paddleInit };

        static int[] paddlesDrawX = new int [2] { screenMinX,
                                                  screenMaxX - paddleWidth + 1 };

        static int[] paddlesDrawY = new int [2] { paddleInit, paddleInit };

        static bool[] inputUp   = new bool [2] { false, false };
        static bool[] inputDown = new bool [2] { false, false };

        static int[] scores = new int [2] { 0, 0 };

        static int lastWinner = 0;

        static bool done = false;
        static bool playing = false;

        static Random random = new Random();

        public static KeyboardDeviceContract.Imp:Ready OpenKeyboard(string! devName)
        {
            KeyboardDeviceContract.Exp! exp;
            KeyboardDeviceContract.Imp! imp;
            KeyboardDeviceContract.NewChannel(out imp, out exp);

            // get NS endpoint
            DirectoryServiceContract.Imp ns = DirectoryService.NewClientEndpoint();

            bool success = false;

            ErrorCode errorOut;
            bool ok = SdsUtils.Bind(devName, ns, exp, out errorOut);
            if (!ok) {
                if (errorOut == ErrorCode.ChannelClosed)
                {
                    throw new Exception("Encountered a ChannelClosed while opening Keyboard");
                }
            }
            else {
                success = true;
            }
            /*
            //            ns.SendBind(Bitter.FromString2(devName),exp);
            switch receive {
            case ns.AckBind():
            success = true;
            break;
            case ns.NakBind(rejected,error):
            delete rejected;
            break;
            case ns.ChannelClosed():
            delete ns;
            throw new Exception("ns unexpectedly closed");
            }
            */
            if (!success) {
                DebugStub.WriteLine("OpenKeyboard lookup of {0} failed\n",
                                    __arglist(devName));

                delete imp;
                delete ns;
                return null;
            }

            switch receive {
                case imp.Success():
                    break;
                case imp.ContractNotSupported():
                    throw new Exception("Contract not supported");
                case imp.ChannelClosed():
                    throw new Exception("Didn't imp.RecvActConnect");
            }

            delete ns;
            return imp;
        }

        public static VideoDeviceContract.Imp:Ready OpenVideo(string! devName)
        {
            VideoDeviceContract.Exp! exp;
            VideoDeviceContract.Imp! imp;
            VideoDeviceContract.NewChannel(out imp, out exp);

            // get NS endpoint
            DirectoryServiceContract.Imp ns = DirectoryService.NewClientEndpoint();

            bool success = false;
            ns.SendBind(Bitter.FromString2(devName),exp);
            switch receive {
                case ns.AckBind():
                    success = true;
                    break;
                case ns.NakBind(rejected, error):
                    delete rejected;
                    break;
                case ns.ChannelClosed():
                    delete ns;
                    throw new Exception("ns unexpectedly closed");
            }

            if (!success) {
                DebugStub.WriteLine("OpenVideo lookup of {0} failed\n",
                                    __arglist(devName));

                delete imp;
                delete ns;
                return null;
            }

            switch receive {
                case imp.Success():
                    break;
                case imp.ContractNotSupported():
                    throw new Exception("Contract not supported");
                case imp.ChannelClosed():
                    throw new Exception("Didn't imp.RecvActConnect");
            }

            delete ns;
            return imp;
        }

        private static void DrawPaddle(VideoDeviceContract.Imp:Ready! video, int paddle, bool erase)
        {
            video.SendFill(paddlesDrawX[paddle],
                           paddlesDrawY[paddle],
                           paddlesDrawX[paddle] + paddleWidth - 1,
                           paddlesDrawY[paddle] + paddleHeight - 1,
                           erase ? Black : Blue);
            video.RecvAckFill();
        }

        private static void RedrawPaddle(VideoDeviceContract.Imp:Ready! video, int paddle)
        {
            if (paddlesDrawY[paddle] != (int) paddlesY[paddle]) {
                DrawPaddle(video, paddle, true);

                paddlesDrawY[paddle] = (int) paddlesY[paddle];

                DrawPaddle(video, paddle, false);
            }
        }

        private static void MovePaddle(VideoDeviceContract.Imp:Ready! video, int paddle)
        {
            paddlesY[paddle] += GetPaddleState(paddle) * paddleSpeed;

            if (paddlesY[paddle] > paddleMax) {
                paddlesY[paddle] = paddleMax;
            }
            else if (paddlesY[paddle] < paddleMin) {
                paddlesY[paddle] = paddleMin;
            }

            RedrawPaddle(video, paddle);
        }

        private static bool PaddleHit(int paddle)
        {
            return ((ballY > paddlesY[paddle] - ballSize) &&
                    (ballY < paddlesY[paddle] + paddleHeight));
        }

        private static void ResetBall()
        {
            ballY = screenMinY + ((screenHeight - ballSize) / 2);
            ballAngle = (random.NextDouble() * ballStartAngle) -
                (ballStartAngle / 2);

            if (lastWinner == 0) {
                ballX = ballMinX;
                if (ballAngle < 0) {
                    ballAngle += 2 * Math.PI;
                }
            }
            else {
                ballX = ballMaxX;
                ballAngle += Math.PI;
            }

            ballDrawX = (int) ballX;
            ballDrawY = (int) ballY;
        }

        private static void DrawBall(VideoDeviceContract.Imp:Ready! video, bool erase)
        {
            video.SendFill(ballDrawX, ballDrawY,
                           ballDrawX + ballSize - 1, ballDrawY + ballSize - 1,
                           erase ? Black : Red);
            video.RecvAckFill();
        }

        private static void RedrawBall(VideoDeviceContract.Imp:Ready! video)
        {
            if (ballDrawX != (int) ballX || ballDrawY != (int) ballY) {
                DrawBall(video, true);

                ballDrawX = (int) ballX;
                ballDrawY = (int) ballY;

                DrawBall(video, false);
            }
        }

        private static void ReflectBallY(int line)
        {
            ballY = (2 * line) - ballY;
            ballAngle = (2 * Math.PI) - ballAngle;
        }

        private static void SetAngle(int paddle)
        {
            // Find out where the ball hit the paddle, from -1 to 1.
            double ratio = ((ballY + (ballSize / 2)) -
                            (paddlesY[paddle] + (paddleHeight / 2))) /
                ((paddleHeight + ballSize) / 2);

            // Set the new angle accordingly.
            ballAngle = ratio * ballMaxAngle;

            if (paddle == 0) {
                if (ballAngle < 0) {
                    ballAngle += 2 * Math.PI;
                }
            }
            else {
                ballAngle = Math.PI - ballAngle;
            }
        }

        private static void MoveBall(VideoDeviceContract.Imp:Ready! video)
        {
            ballY += Math.Sin(ballAngle) * ballSpeed;
            if (ballY < ballMinY) {
                ReflectBallY(ballMinY);
            }
            else if (ballY > ballMaxY) {
                ReflectBallY(ballMaxY);
            }

            ballX += Math.Cos(ballAngle) * ballSpeed;
            if (ballX < ballMinX) {
                if (PaddleHit(0)) {
                    SetAngle(0);
                }
                else {
                    lastWinner = 1;
                    playing = false;
                }
            }
            else if (ballX > ballMaxX) {
                if (PaddleHit(1)) {
                    SetAngle(1);
                }
                else {
                    lastWinner = 0;
                    playing = false;
                }
            }

            RedrawBall(video);
        }

        private static int GetPaddleState(int paddle)
        {
            if (inputUp[paddle]) {
                return -1;
            }
            else if (inputDown[paddle]) {
                return 1;
            }
            else {
                return 0;
            }
        }

        private static void SetStateFromChar(char c, bool @state)
        {
            switch (c) {
                case (char)Keyboard.Keys.UP_ARROW:
                    inputUp[1] = @state;
                    break;
                case (char)Keyboard.Keys.DOWN_ARROW:
                    inputDown[1] = @state;
                    break;
                case 'a':
                    inputUp[0] = @state;
                    break;
                case 'z':
                    inputDown[0] = @state;
                    break;
            }
        }

        private static void FillScreen(VideoDeviceContract.Imp:Ready! video, uint color)
        {
            video.SendFill(screenMinX, screenMinY, screenMaxX, screenMaxY, color);
            video.RecvAckFill();
        }

        private static void ClearScreen(VideoDeviceContract.Imp:Ready! video)
        {
            FillScreen(video, Black);
        }

        private static void FlashScreen(VideoDeviceContract.Imp:Ready! video)
        {
            FillScreen(video, Red);
            Sleep(1000);
            FillScreen(video, Green);
            Sleep(1000);
            FillScreen(video, Blue);
            Sleep(1000);
        }

        private static void ShowMessage(VideoDeviceContract.Imp:Ready! video)
        {
            ClearScreen(video);

            for (int i = 0; i < 100; i++) {
                Console.WriteLine();
            }

            Console.Write("                                 ");
            Console.Write("Left: {0,-10}", scores[0]);
            Console.Write("                                 ");
            Console.Write("Right: {0,-10}", scores[1]);
            Console.WriteLine();
            Console.WriteLine();
            Console.Write("                                         ");
            Console.Write("Press space to begin or escape to quit...");
            Console.WriteLine();

            DrawPaddle(video, 0, false);
            DrawPaddle(video, 1, false);
            DrawBall(video, false);
        }

        private static void Sleep(int multiplier)
        {
            for (int j = 0; j < multiplier; j++) {
                for (int i = 0; i < 10000; i++) {
                    // Do nothing.
                }
            }
        }

        public static int Main(string[] args)
        {
            VideoDeviceContract.Imp video = OpenVideo("/dev/video");

            Console.WriteLine("Singularity Pong (PID={0})",
                              ProcessService.GetCurrentProcessId());

            if (video == null) {
                Console.WriteLine("Can only play pong on a graphic display.");
                return 1;
            }

            KeyboardDeviceContract.Imp keyboard = OpenKeyboard("/dev/keyboard");
            if (keyboard == null) {
                // TODO: show keyboardless slides with timer?
                delete video;
                return 1;
            }

            ShowMessage(video);

            while (!done) {
                uint key = 0;
                keyboard.SendPollKey();
                switch receive
                {
                    case keyboard.AckKey(ikey):
                        key = ikey;
                        break;
                    case keyboard.NakKey():
                        key = 0;
                        break;
                    case keyboard.ChannelClosed():
                        throw new Exception("Didn't get keyboard closed.");
                }

                char c = (char) (key & (uint) Keyboard.Qualifiers.KEY_BASE_CODE);

                if ((key & (uint) Keyboard.Qualifiers.KEY_DOWN) != 0) {
                    switch (c) {
                        case (char) Keyboard.Keys.ESCAPE:
                            done = true;
                            break;
                        case ' ':
                            if (!playing) {
                                ResetBall();
                                ClearScreen(video);
                                DrawPaddle(video, 0, false);
                                DrawPaddle(video, 1, false);
                                DrawBall(video, false);
                                playing = true;
                            }
                            break;
                        default:
                            SetStateFromChar(c, true);
                            break;
                    }
                }
                else if ((key & (uint) Keyboard.Qualifiers.KEY_UP) != 0) {
                    SetStateFromChar(c, false);
                }

                if (playing) {
                    MovePaddle(video, 0);
                    MovePaddle(video, 1);
                    MoveBall(video);

                    if (!playing) {
                        scores[lastWinner]++;
                        FlashScreen(video);
                        ShowMessage(video);
                    }
                }

                Sleep(10);
            }

            ClearScreen(video);

            delete keyboard;
            delete video;

            return 0;
        }
    }
}