Main game loop with Short Range Scan and Shield Control

84 Super Star Trek/csharp/Command.cs

@@ -0,0 +1,34 @@
+using System.ComponentModel;
+
+namespace SuperStarTrek
+{
+    internal enum Command
+    {
+        [Description("To set course")]
+        NAV,
+
+        [Description("For short range sensor scan")]
+        SRS,
+
+        [Description("For long range sensor scan")]
+        LRS,
+
+        [Description("To fire phasers")]
+        PHA,
+
+        [Description("To fire photon torpedoes")]
+        TOR,
+
+        [Description("To raise or lower shields")]
+        SHE,
+
+        [Description("For damage control reports")]
+        DAM,
+
+        [Description("To call on library-computer")]
+        COM,
+
+        [Description("To resign your command")]
+        XXX
+    }
+}

84 Super Star Trek/csharp/CommandExtensions.cs

@@ -0,0 +1,14 @@
+using System.Reflection;
+using System.ComponentModel;
+
+namespace SuperStarTrek
+{
+    internal static class CommandExtensions
+    {
+        internal static string GetDescription(this Command command) =>
+            typeof(Command)
+                .GetField(command.ToString())
+                .GetCustomAttribute<DescriptionAttribute>()
+                .Description;
+    }
+}

84 Super Star Trek/csharp/Game.cs

@@ -0,0 +1,97 @@
+using System;
+using SuperStarTrek.Objects;
+using SuperStarTrek.Resources;
+using SuperStarTrek.Space;
+using SuperStarTrek.Systems;
+using static System.StringComparison;
+
+namespace SuperStarTrek
+{
+    internal class Game
+    {
+        private readonly Output _output;
+        private readonly Input _input;
+
+        private int _initialStardate;
+        private int _finalStarDate;
+        private double _currentStardate;
+        private Coordinates _currentQuadrant;
+        private Coordinates _currentSector;
+        private Galaxy _galaxy;
+        private int _initialKlingonCount;
+        private Enterprise _enterprise;
+
+        public Game()
+        {
+            _output = new Output();
+            _input = new Input(_output);
+        }
+
+        public double Stardate => _currentStardate;
+
+        public void DoIntroduction()
+        {
+            _output.Write(Strings.Title);
+
+            _output.Write("Do you need instructions (Y/N)? ");
+            var response = Console.ReadLine();
+            _output.WriteLine();
+
+            if (!response.Equals("N", InvariantCultureIgnoreCase))
+            {
+                _output.Write(Strings.Instructions);
+
+                _input.WaitForAnyKeyButEnter("to continue");
+            }
+        }
+
+        public void Play()
+        {
+            var quadrant = Initialise();
+            var gameOver = false;
+
+            _output.Write(Strings.Enterprise);
+            _output.Write(
+                Strings.Orders,
+                _galaxy.KlingonCount,
+                _finalStarDate,
+                _finalStarDate - _initialStardate,
+                _galaxy.StarbaseCount > 1 ? "are" : "is",
+                _galaxy.StarbaseCount,
+                _galaxy.StarbaseCount > 1 ? "s" : "");
+
+            _input.WaitForAnyKeyButEnter("when ready to accept command");
+
+            _enterprise.Enter(quadrant, Strings.StartText);
+
+            while (!gameOver)
+            {
+                var command = _input.GetCommand();
+
+                gameOver = command == Command.XXX || _enterprise.Execute(command);
+            }
+        }
+
+        private Quadrant Initialise()
+        {
+            var random = new Random();
+
+            _currentStardate = _initialStardate = random.GetInt(20, 40) * 100;
+            _finalStarDate = _initialStardate + random.GetInt(25, 35);
+
+            _currentQuadrant = random.GetCoordinate();
+            _currentSector = random.GetCoordinate();
+
+            _galaxy = new Galaxy();
+            _initialKlingonCount = _galaxy.KlingonCount;
+
+            _enterprise = new Enterprise(3000, random.GetCoordinate());
+            _enterprise.Add(new ShortRangeSensors(_enterprise, _galaxy, this, _output))
+                .Add(new ShieldControl(_enterprise, _output, _input));
+
+            return new Quadrant(_galaxy[_currentQuadrant], _enterprise);
+        }
+
+        public bool Replay() => _galaxy.StarbaseCount > 0 && _input.GetString(Strings.ReplayPrompt, "Aye");
+    }
+}

84 Super Star Trek/csharp/Input.cs

@@ -0,0 +1,76 @@
+using System;
+using System.Linq;
+using static System.StringComparison;
+
+namespace SuperStarTrek
+{
+    internal class Input
+    {
+        private readonly Output _output;
+
+        public Input(Output output)
+        {
+            _output = output;
+        }
+
+        public void WaitForAnyKeyButEnter(string prompt)
+        {
+            _output.Write($"Hit any key but Enter {prompt} ");
+            while (Console.ReadKey(intercept: true).Key == ConsoleKey.Enter);
+        }
+
+        public string GetString(string prompt)
+        {
+            _output.Prompt(prompt);
+            return Console.ReadLine();
+        }
+
+        public double GetNumber(string prompt)
+        {
+            _output.Prompt(prompt);
+
+            while (true)
+            {
+                var response = Console.ReadLine();
+                if (double.TryParse(response, out var value))
+                {
+                    return value;
+                }
+
+                _output.WriteLine("!Number expected - retry input line");
+                _output.Prompt();
+            }
+        }
+
+        public bool TryGetNumber(string prompt, double minValue, double maxValue, out double value)
+        {
+            value = GetNumber($"{prompt} ({minValue}-{maxValue})");
+
+            return value >= minValue && value <= maxValue;
+        }
+
+        internal bool GetString(string replayPrompt, string trueValue)
+            => GetString(replayPrompt).Equals(trueValue, InvariantCultureIgnoreCase);
+
+        public Command GetCommand()
+        {
+            while(true)
+            {
+                var response = GetString("Command");
+
+                if (response != "" &&
+                    Enum.TryParse(response.Substring(0, 3), ignoreCase: true, out Command parsedCommand))
+                {
+                    return parsedCommand;
+                }
+
+                _output.WriteLine("Enter one of the following:");
+                foreach (var command in Enum.GetValues(typeof(Command)).OfType<Command>())
+                {
+                    _output.WriteLine($"  {command}  ({command.GetDescription()})");
+                }
+                _output.WriteLine();
+            }
+        }
+    }
+}

84 Super Star Trek/csharp/Objects/Enterprise.cs

@@ -0,0 +1,103 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using SuperStarTrek.Resources;
+using SuperStarTrek.Space;
+using SuperStarTrek.Systems;
+
+namespace SuperStarTrek.Objects
+{
+    internal class Enterprise
+    {
+        private readonly int _maxEnergy;
+        private readonly List<Subsystem> _systems;
+        private readonly Dictionary<Command, Subsystem> _commandExecutors;
+        private Quadrant _quadrant;
+        private ShieldControl _shieldControl;
+
+        public Enterprise(int maxEnergy, Coordinates sector)
+        {
+            Sector = sector;
+            TotalEnergy = _maxEnergy = maxEnergy;
+
+            _systems = new List<Subsystem>();
+            _commandExecutors = new Dictionary<Command, Subsystem>();
+        }
+
+        public Coordinates Quadrant => _quadrant.Coordinates;
+        public Coordinates Sector { get; }
+        public string Condition => GetCondition();
+        public double Shields => _shieldControl.Energy;
+        public double Energy => TotalEnergy - Shields;
+        public double TotalEnergy { get; private set; }
+        public int TorpedoCount { get; }
+
+        public bool IsDocked { get; private set; }
+
+        public Enterprise Add(Subsystem system)
+        {
+            _systems.Add(system);
+            _commandExecutors[system.Command] = system;
+
+            if (system is ShieldControl shieldControl) { _shieldControl = shieldControl; }
+
+            return this;
+        }
+
+        public string GetDamageReport()
+        {
+            var report = new StringBuilder();
+            report.AppendLine().AppendLine().AppendLine("Device             State of Repair");
+            foreach (var system in _systems)
+            {
+                report.Append(system.Name.PadRight(25)).AppendLine(system.Condition.ToString(" 0.00;-0.00"));
+            }
+            report.AppendLine();
+            return report.ToString();
+        }
+
+        public void Enter(Quadrant quadrant, string entryTextFormat)
+        {
+            _quadrant = quadrant;
+
+            var _output = new Output();
+            _output.Write(entryTextFormat, quadrant);
+
+            if (quadrant.HasKlingons)
+            {
+                _output.Write(Strings.CombatArea);
+                if (Shields <= 200) { _output.Write(Strings.LowShields); }
+            }
+
+            IsDocked = quadrant.EnterpriseIsNextToStarbase;
+
+            Execute(Command.SRS);
+        }
+
+        private string GetCondition() =>
+            (_quadrant.HasKlingons, Energy / _maxEnergy) switch
+            {
+                (true, _) => "*Red*",
+                (_, < 0.1) => "Yellow",
+                _ => "Green"
+            };
+
+        public bool Execute(Command command)
+        {
+            _commandExecutors[command].ExecuteCommand(_quadrant);
+            return false;
+        }
+
+        internal bool Recognises(string command)
+        {
+            throw new NotImplementedException();
+        }
+
+        internal string GetCommandList()
+        {
+            throw new NotImplementedException();
+        }
+
+        public override string ToString() => "<*>";
+    }
+}

84 Super Star Trek/csharp/Objects/Klingon.cs

@@ -0,0 +1,14 @@
+namespace SuperStarTrek.Objects
+{
+    internal class Klingon
+    {
+        private double _energy;
+
+        public Klingon()
+        {
+            _energy = new Random().GetDouble(100, 300);
+        }
+
+        public override string ToString() => "+K+";
+    }
+}

84 Super Star Trek/csharp/Objects/Star.cs

@@ -0,0 +1,7 @@
+namespace SuperStarTrek.Objects
+{
+    internal class Star
+    {
+        public override string ToString() => " * ";
+    }
+}

84 Super Star Trek/csharp/Objects/Starbase.cs

@@ -0,0 +1,7 @@
+namespace SuperStarTrek.Objects
+{
+    internal class Starbase
+    {
+        public override string ToString() => ">!<";
+    }
+}

84 Super Star Trek/csharp/Output.cs

@@ -0,0 +1,15 @@
+using System;
+
+namespace SuperStarTrek
+{
+    internal class Output
+    {
+        public void Write(string text) => Console.Write(text);
+        public void Write(string format, params object[] args) => Console.Write(format, args);
+        public void WriteLine(string text = "") => Console.WriteLine(text);
+
+        public void NextLine() => Console.WriteLine();
+
+        public void Prompt(string text = "") => Console.Write($"{text}? ");
+    }
+}

84 Super Star Trek/csharp/Program.cs

@@ -23,31 +23,20 @@
 // ****  CONVERTED TO MICROSOFT C# 2/20/21 BY ANDREW COOPER
 // ****
 
-using System;
-
-using static System.StringComparison;
-
 namespace SuperStarTrek
 {
-    class Program
+    internal class Program
     {
-        static void Main(string[] args)
+        static void Main()
         {
-            Console.WriteLine(Strings.Title);
+            var game = new Game();
 
-            Console.Write("Do you need instructions (Y/N)? ");
-            var response = Console.ReadLine();
-            Console.WriteLine();
+            game.DoIntroduction();
 
-            if (!response.Equals("N", InvariantCultureIgnoreCase))
+            do
             {
-                Console.WriteLine(Strings.Instructions);
-
-                Console.WriteLine("Press <Enter> to continue...");
-                Console.ReadLine();
-            }
-
-            Console.WriteLine(Strings.Enterprise);
+                game.Play();
+            } while (game.Replay());
         }
     }
 }

84 Super Star Trek/csharp/Random.cs

@@ -0,0 +1,25 @@
+using SuperStarTrek.Space;
+
+namespace SuperStarTrek
+{
+    internal class Random
+    {
+        private static readonly System.Random _random = new();
+
+        public Coordinates GetCoordinate() => new Coordinates(Get1To8Inclusive(), Get1To8Inclusive());
+
+        // Duplicates the algorithm used in the original code to get an integer value from 1 to 8, inclusive:
+        //     475 DEF FNR(R)=INT(RND(R)*7.98+1.01)
+        // Returns a value from 1 to 8, inclusive.
+        // Note there's a slight bias away from the extreme values, 1 and 8.
+        public int Get1To8Inclusive() => (int)(_random.NextDouble() * 7.98 + 1.01);
+
+        public int GetInt(int inclusiveMinValue, int exclusiveMaxValue) =>
+            _random.Next(inclusiveMinValue, exclusiveMaxValue);
+
+        public double GetDouble() => _random.NextDouble();
+
+        public double GetDouble(double inclusiveMinValue, double exclusiveMaxValue)
+            => _random.NextDouble() * (exclusiveMaxValue - inclusiveMinValue) + inclusiveMinValue;
+    }
+}

84 Super Star Trek/csharp/Resources/CombatArea.txt

@@ -0,0 +1 @@
+COMBAT AREA      CONDITION RED

84 Super Star Trek/csharp/Resources/Instructions.txt

@@ -53,7 +53,7 @@ LRS command = Long Range Sensor Scan
      The scan is coded in the form ###, where the units digit
      is the number of stars, the tens digit is the number of
      starbases, and the hundreds digit is the number of
-     Kilngons.
+     Klingons.
 
      Example - 207 = 2 Klingons, No starbases, & 7 stars.
 
@@ -103,3 +103,4 @@ COM command = Library-Computer
      Option 5 = Galactic Region Name Map
         This option prints the names of the sixteen major
         galactic regions referred to in the game.
+

84 Super Star Trek/csharp/Resources/LowShields.txt

@@ -0,0 +1 @@
+   SHIELDS DANGEROUSLY LOW

84 Super Star Trek/csharp/Resources/Orders.txt

@@ -0,0 +1,6 @@
+Your orders are as follows:
+    Destroy the {0} Klingon warships which have invaded
+  the galaxy before they can attack federation headquarters
+  on stardate {1}. This gives you {2} days. There {3}
+  {4} starbase{5} in the galaxy for resupplying your ship.
+

84 Super Star Trek/csharp/Resources/ReplayPrompt.txt

@@ -0,0 +1,3 @@
+The Federation is in need of a new starship commander
+for a similar mission -- if there is a volunteer
+let him step forward and enter 'Aye'

84 Super Star Trek/csharp/Resources/ShieldsDropped.txt

@@ -0,0 +1 @@
+Shields dropped for docking purposes

84 Super Star Trek/csharp/Resources/ShortRangeSensorsOut.txt

@@ -0,0 +1 @@
+*** Short Range Sensors are out ***

84 Super Star Trek/csharp/Resources/StartText.txt

@@ -0,0 +1,5 @@
+
+
+Your mission begins with your starship located
+in the galactic quadrant, '{0}'.
+

84 Super Star Trek/csharp/Resources/Strings.cs

@@ -2,15 +2,20 @@
 using System.Reflection;
 using System.Runtime.CompilerServices;
 
-using static System.StringComparison;
-
-namespace SuperStarTrek
+namespace SuperStarTrek.Resources
 {
     internal static class Strings
     {
-        public static string Title => GetResource();
-        public static string Instructions => GetResource();
+        public static string CombatArea => GetResource();
         public static string Enterprise => GetResource();
+        public static string Instructions => GetResource();
+        public static string LowShields => GetResource();
+        public static string Orders => GetResource();
+        public static string ReplayPrompt => GetResource();
+        public static string ShieldsDropped => GetResource();
+        public static string ShortRangeSensorsOut => GetResource();
+        public static string StartText => GetResource();
+        public static string Title => GetResource();
 
         private static string GetResource([CallerMemberName] string name = "")
         {

84 Super Star Trek/csharp/Space/Coordinate.cs

@@ -0,0 +1,27 @@
+using System;
+
+namespace SuperStarTrek.Space
+{
+    // Represents the corrdintate of a quadrant in the galaxy, or a sector in a quadrant.
+    // Note that the origin is top-left, x increase downwards, and y increases to the right.
+    internal record Coordinates
+    {
+        public Coordinates(int x, int y)
+        {
+            X = Validated(x, nameof(x));
+            Y = Validated(y, nameof(y));
+        }
+
+        public int X { get; }
+        public int Y { get; }
+
+        private int Validated(int value, string argumentName)
+        {
+            if (value >= 1 && value <= 8) { return value; }
+
+            throw new ArgumentOutOfRangeException(argumentName, value, "Must be 1 to 8 inclusive");
+        }
+
+        public override string ToString() => $"{X} , {Y}";
+    }
+}

84 Super Star Trek/csharp/Space/Course.cs

@@ -0,0 +1,50 @@
+using System;
+
+namespace SuperStarTrek.Space
+{
+    // Implements the course calculations from the original code:
+    //     530 FORI=1TO9:C(I,1)=0:C(I,2)=0:NEXTI
+    //     540 C(3,1)=-1:C(2,1)=-1:C(4,1)=-1:C(4,2)=-1:C(5,2)=-1:C(6,2)=-1
+    //     600 C(1,2)=1:C(2,2)=1:C(6,1)=1:C(7,1)=1:C(8,1)=1:C(8,2)=1:C(9,2)=1
+    //
+    //     3110 X1=C(C1,1)+(C(C1+1,1)-C(C1,1))*(C1-INT(C1))
+    //     3140 X2=C(C1,2)+(C(C1+1,2)-C(C1,2))*(C1-INT(C1))
+    internal class Course
+    {
+        private static readonly (int DeltaX, int DeltaY)[] cardinals = new[]
+        {
+            (0, 1),
+            (-1, 1),
+            (-1, 0),
+            (-1, -1),
+            (0, -1),
+            (1, -1),
+            (1, 0),
+            (1, 1),
+            (0, 1)
+        };
+
+        public Course(double direction)
+        {
+            if (direction < 1 || direction > 9)
+            {
+                throw new ArgumentOutOfRangeException(
+                    nameof(direction),
+                    direction,
+                    "Must be between 1 and 9, inclusive.");
+            }
+
+            var cardinalDirection = (int)(direction - 1) % 8;
+            var fractionalDirection = direction - (int)direction;
+
+            var baseCardinal = cardinals[cardinalDirection];
+            var nextCardinal = cardinals[cardinalDirection + 1];
+
+            DeltaX = baseCardinal.DeltaX + (nextCardinal.DeltaX - baseCardinal.DeltaX) * fractionalDirection;
+            DeltaY = baseCardinal.DeltaY + (nextCardinal.DeltaY - baseCardinal.DeltaY) * fractionalDirection;
+        }
+
+        public double DeltaX { get; }
+        public double DeltaY { get; }
+    }
+}

84 Super Star Trek/csharp/Space/Galaxy.cs

@@ -0,0 +1,34 @@
+using System.Linq;
+
+namespace SuperStarTrek.Space
+{
+    internal class Galaxy
+    {
+        private readonly QuadrantInfo[][] _quadrants;
+
+        public Galaxy()
+        {
+            var random = new Random();
+
+            _quadrants = Enumerable.Range(1, 8).Select(x =>
+                Enumerable.Range(1, 8).Select(y => QuadrantInfo.Create(new Coordinates(x, y), "")).ToArray())
+                .ToArray();
+
+            if (StarbaseCount == 0)
+            {
+                var randomQuadrant = this[random.GetCoordinate()];
+                randomQuadrant.AddStarbase();
+
+                if (randomQuadrant.KlingonCount < 2)
+                {
+                    randomQuadrant.AddKlingon();
+                }
+            }
+        }
+
+        public QuadrantInfo this[Coordinates coordinate] => _quadrants[coordinate.X - 1][coordinate.Y - 1];
+
+        public int KlingonCount => _quadrants.SelectMany(q => q).Sum(q => q.KlingonCount);
+        public int StarbaseCount => _quadrants.SelectMany(q => q).Count(q => q.HasStarbase);
+    }
+}

84 Super Star Trek/csharp/Space/Quadrant.cs

@@ -0,0 +1,79 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using SuperStarTrek.Objects;
+
+namespace SuperStarTrek.Space
+{
+    internal class Quadrant
+    {
+        private readonly QuadrantInfo _info;
+        private readonly Random _random;
+        private readonly Dictionary<Coordinates, object> _sectors;
+        private readonly Coordinates _enterpriseSector;
+        private readonly Coordinates _starbaseSector;
+
+        public Quadrant(QuadrantInfo info, Enterprise enterprise)
+        {
+            _info = info;
+            _random = new Random();
+
+            _enterpriseSector = enterprise.Sector;
+            _sectors = new Dictionary<Coordinates, object> { [enterprise.Sector] = enterprise };
+            PositionObject(() => new Klingon(), _info.KlingonCount);
+            if (_info.HasStarbase)
+            {
+                _starbaseSector = PositionObject(() => new Starbase());
+            }
+            PositionObject(() => new Star(), _info.StarCount);
+        }
+
+        public Coordinates Coordinates => _info.Coordinates;
+        public bool HasKlingons => _info.KlingonCount > 0;
+        public bool HasStarbase => _info.HasStarbase;
+        public bool EnterpriseIsNextToStarbase =>
+            _info.HasStarbase &&
+            Math.Abs(_enterpriseSector.X - _starbaseSector.X) <= 1 &&
+            Math.Abs(_enterpriseSector.Y - _starbaseSector.Y) <= 1;
+
+        public override string ToString() => _info.Name;
+
+        private Coordinates PositionObject(Func<object> objectFactory)
+        {
+            var sector = GetRandomEmptySector();
+            _sectors[sector] = objectFactory.Invoke();
+            return sector;
+        }
+
+        private void PositionObject(Func<object> objectFactory, int count)
+        {
+            for (int i = 0; i < count; i++)
+            {
+                PositionObject(objectFactory);
+            }
+        }
+
+        private Coordinates GetRandomEmptySector()
+        {
+            while (true)
+            {
+                var sector = _random.GetCoordinate();
+                if (!_sectors.ContainsKey(sector))
+                {
+                    return sector;
+                }
+            }
+        }
+
+        public IEnumerable<string> GetDisplayLines() => Enumerable.Range(1, 8).Select(x => GetDisplayLine(x));
+
+        private string GetDisplayLine(int x)
+            => string.Join(
+                " ",
+                Enumerable
+                    .Range(1, 8)
+                    .Select(y => new Coordinates(x, y))
+                    .Select(c => _sectors.GetValueOrDefault(c))
+                    .Select(o => o?.ToString() ?? "   "));
+    }
+}

84 Super Star Trek/csharp/Space/QuadrantInfo.cs

@@ -0,0 +1,40 @@
+namespace SuperStarTrek.Space
+{
+    internal class QuadrantInfo
+    {
+        private QuadrantInfo(Coordinates coordinates, string name, int klingonCount, int starCount, bool hasStarbase)
+        {
+            Coordinates = coordinates;
+            Name = name;
+            KlingonCount = klingonCount;
+            StarCount = starCount;
+            HasStarbase = hasStarbase;
+        }
+
+        public Coordinates Coordinates { get; }
+        public string Name { get; }
+        public int KlingonCount { get; private set; }
+        public bool HasStarbase { get; private set; }
+        public int StarCount { get; }
+
+        public static QuadrantInfo Create(Coordinates coordinates, string name)
+        {
+            var random = new Random();
+            var klingonCount = random.GetDouble() switch
+            {
+                > 0.98 => 3,
+                > 0.95 => 2,
+                > 0.80 => 1,
+                _ => 0
+            };
+            var hasStarbase = random.GetDouble() > 0.96;
+            var starCount = random.Get1To8Inclusive();
+
+            return new QuadrantInfo(coordinates, name, klingonCount, starCount, hasStarbase);
+        }
+
+        internal void AddKlingon() => KlingonCount += 1;
+
+        internal void AddStarbase() => HasStarbase = true;
+    }
+}

84 Super Star Trek/csharp/Systems/ShieldControl.cs

@@ -0,0 +1,53 @@
+using SuperStarTrek.Objects;
+using SuperStarTrek.Space;
+
+namespace SuperStarTrek.Systems
+{
+    internal class ShieldControl : Subsystem
+    {
+        private readonly Enterprise _enterprise;
+        private readonly Output _output;
+        private readonly Input _input;
+
+        public ShieldControl(Enterprise enterprise, Output output, Input input)
+            : base("Shield Control", Command.SHE)
+        {
+            _enterprise = enterprise;
+            _output = output;
+            _input = input;
+        }
+
+        public double Energy { get; private set; }
+
+        public override void ExecuteCommand(Quadrant quadrant)
+        {
+            if (Condition < 0)
+            {
+                _output.WriteLine("Shield Control inoperable");
+                return;
+            }
+
+            _output.WriteLine($"Energy available = {_enterprise.TotalEnergy}");
+            var requested = _input.GetNumber($"Number of units to shields");
+
+            if (Validate(requested))
+            {
+                Energy = requested;
+                return;
+            }
+
+            _output.WriteLine("<SHIELDS UNCHANGED>");
+        }
+
+        private bool Validate(double requested)
+        {
+            if (requested > _enterprise.TotalEnergy)
+            {
+                _output.WriteLine("Shield Control reports, 'This is not the Federation Treasury.'");
+                return false;
+            }
+
+            return requested >= 0 && requested != Energy;
+        }
+    }
+}

84 Super Star Trek/csharp/Systems/ShortRangeSensors.cs

@@ -0,0 +1,59 @@
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using SuperStarTrek.Objects;
+using SuperStarTrek.Resources;
+using SuperStarTrek.Space;
+
+namespace SuperStarTrek.Systems
+{
+    internal class ShortRangeSensors : Subsystem
+    {
+        private readonly Enterprise _enterprise;
+        private readonly Galaxy _galaxy;
+        private readonly Game _game;
+        private readonly Output _output;
+
+        public ShortRangeSensors(Enterprise enterprise, Galaxy galaxy, Game game, Output output)
+            : base("Short Range Sensors", Command.SRS)
+        {
+            _enterprise = enterprise;
+            _galaxy = galaxy;
+            _game = game;
+            _output = output;
+        }
+
+        public override void ExecuteCommand(Quadrant quadrant)
+        {
+            if (_enterprise.IsDocked)
+            {
+                _output.WriteLine(Strings.ShieldsDropped);
+            }
+
+            if (Condition < 0)
+            {
+                _output.WriteLine(Strings.ShortRangeSensorsOut);
+            }
+
+            _output.WriteLine("---------------------------------");
+            quadrant.GetDisplayLines()
+                .Zip(GetStatusLines(), (sectors, status) => $" {sectors}         {status}")
+                .ToList()
+                .ForEach(l => _output.WriteLine(l));
+            _output.WriteLine("---------------------------------");
+        }
+
+        public IEnumerable<string> GetStatusLines()
+        {
+            yield return $"Stardate           {_game.Stardate}";
+            yield return $"Condition          {_enterprise.Condition}";
+            yield return $"Quadrant           {_enterprise.Quadrant}";
+            yield return $"Sector             {_enterprise.Sector}";
+            yield return $"Photon torpedoes   {_enterprise.TorpedoCount}";
+            yield return $"Total energy       {Math.Ceiling(_enterprise.Energy)}";
+            yield return $"Shields            {(int)_enterprise.Shields}";
+            yield return $"Klingons remaining {_galaxy.KlingonCount}";
+        }
+    }
+}

84 Super Star Trek/csharp/Systems/Subsystem.cs

@@ -0,0 +1,20 @@
+using SuperStarTrek.Space;
+
+namespace SuperStarTrek.Systems
+{
+    internal abstract class Subsystem
+    {
+        protected Subsystem(string name, Command command)
+        {
+            Name = name;
+            Command = command;
+            Condition = 0;
+        }
+
+        public string Name { get; }
+        public double Condition { get; }
+        public Command Command { get; }
+
+        public abstract void ExecuteCommand(Quadrant quadrant);
+    }
+}