diff --git a/command/remoteundostatus/app.d b/command/remoteundostatus/app.d
new file mode 100644
index 0000000..3c9b6fa
--- /dev/null
+++ b/command/remoteundostatus/app.d
@@ -0,0 +1,36 @@
+module command.remoteundostatus.app;
+
+import command.remoteundostatus.remotecontrol;
+import command.remoteundostatus.lightoncommand;
+import command.remoteundostatus.lightoffcommand;
+import command.remoteundostatus.light;
+import command.remoteundostatus.ceilingfan;
+import command.remoteundostatus.ceilingfanoffcommand;
+import command.remoteundostatus.ceilingfanhighcommand;
+import command.remoteundostatus.ceilingfanmediumcommand;
+import command.remoteundostatus.ceilingfanlowcommand;
+import command.remoteundostatus.garagedoorupcommand;
+import command.remoteundostatus.garagedoordowncommand;
+import command.remoteundostatus.garagedoor;
+import command.remoteundostatus.stereoonwithcdcommand;
+import command.remoteundostatus.stereo;
+import command.remoteundostatus.stereooffcommand;
+import std.stdio : writeln;
+
+void main()
+{
+    auto remoteControl = new RemoteControl();
+
+    auto ceilingFan = new CeilingFan("Living Room");
+
+    remoteControl.setCommand(0, new CeilingFanMediumCommand(ceilingFan), new CeilingFanOffCommand(ceilingFan));
+    remoteControl.setCommand(1, new CeilingFanHighCommand(ceilingFan), new CeilingFanOffCommand(ceilingFan));
+
+    remoteControl.onButtonWasPushed(0);
+    remoteControl.offButtonWasPushed(0);
+    writeln(remoteControl);
+    remoteControl.undoButtonWasPushed();
+    remoteControl.onButtonWasPushed(1);
+    writeln(remoteControl);
+    remoteControl.undoButtonWasPushed();
+}
\ No newline at end of file
diff --git a/command/remoteundostatus/ceilingfan.d b/command/remoteundostatus/ceilingfan.d
new file mode 100644
index 0000000..fc2e9b7
--- /dev/null
+++ b/command/remoteundostatus/ceilingfan.d
@@ -0,0 +1,49 @@
+module command.remoteundostatus.ceilingfan;
+
+import std.stdio : writeln;
+
+class CeilingFan
+{
+    private string location;
+    private int speed;
+
+    static const int HIGH = 3;
+    static const int MEDIUM = 2;
+    static const int LOW = 1;
+    static const int OFF = 0;
+
+    this(string location)
+    {
+        this.location = location;
+    }
+    
+    void high()
+    {
+        speed = HIGH;
+        writeln(location ~ " ceiling fan is on high");
+ 
+    } 
+
+    void medium()
+    {
+        speed = MEDIUM;
+        writeln(location ~ " ceiling fan is on medium");
+    }
+
+    void low()
+    {
+        speed = LOW;
+        writeln(location ~ " ceiling fan is on low");
+    }
+ 
+    void off()
+    {
+        speed = OFF;
+        writeln(location ~ " ceiling fan is off");
+    }
+ 
+    int getSpeed()
+    {
+        return speed;
+    }
+}
diff --git a/command/remoteundostatus/ceilingfanhighcommand.d b/command/remoteundostatus/ceilingfanhighcommand.d
new file mode 100644
index 0000000..c591fe4
--- /dev/null
+++ b/command/remoteundostatus/ceilingfanhighcommand.d
@@ -0,0 +1,41 @@
+module command.remoteundostatus.ceilingfanhighcommand;
+
+import command.remoteundostatus.command;
+import command.remoteundostatus.ceilingfan;
+
+class CeilingFanHighCommand : Command
+{
+    CeilingFan ceilingFan;
+    int prevSpeed;
+
+    this(CeilingFan ceilingFan)
+    {
+        this.ceilingFan = ceilingFan;
+    }
+
+    void execute()
+    {
+        prevSpeed = ceilingFan.getSpeed();
+        ceilingFan.high();
+    }
+
+    void undo()
+    {
+        switch (prevSpeed)
+        {
+            case CeilingFan.HIGH:
+                ceilingFan.high();
+                break;
+            case CeilingFan.MEDIUM:
+                ceilingFan.medium();
+                break;
+            case CeilingFan.LOW:
+                ceilingFan.low();
+                break;
+            case CeilingFan.OFF:
+                ceilingFan.off();
+                break;
+            default: break;
+        }
+    }
+}
diff --git a/command/remoteundostatus/ceilingfanlowcommand.d b/command/remoteundostatus/ceilingfanlowcommand.d
new file mode 100644
index 0000000..a815785
--- /dev/null
+++ b/command/remoteundostatus/ceilingfanlowcommand.d
@@ -0,0 +1,41 @@
+module command.remoteundostatus.ceilingfanlowcommand;
+
+import command.remoteundostatus.command;
+import command.remoteundostatus.ceilingfan;
+
+class CeilingFanLowCommand : Command
+{
+    CeilingFan ceilingFan;
+    int prevSpeed;
+
+    this(CeilingFan ceilingFan)
+    {
+        this.ceilingFan = ceilingFan;
+    }
+
+    void execute()
+    {
+        prevSpeed = ceilingFan.getSpeed();
+        ceilingFan.low();
+    }
+
+    void undo()
+    {
+        switch (prevSpeed)
+        {
+            case CeilingFan.HIGH:
+                ceilingFan.high();
+                break;
+            case CeilingFan.MEDIUM:
+                ceilingFan.medium();
+                break;
+            case CeilingFan.LOW:
+                ceilingFan.low();
+                break;
+            case CeilingFan.OFF:
+                ceilingFan.off();
+                break;
+            default: break;
+        }
+    }
+}
diff --git a/command/remoteundostatus/ceilingfanmediumcommand.d b/command/remoteundostatus/ceilingfanmediumcommand.d
new file mode 100644
index 0000000..de974b0
--- /dev/null
+++ b/command/remoteundostatus/ceilingfanmediumcommand.d
@@ -0,0 +1,41 @@
+module command.remoteundostatus.ceilingfanmediumcommand;
+
+import command.remoteundostatus.command;
+import command.remoteundostatus.ceilingfan;
+
+class CeilingFanMediumCommand : Command
+{
+    CeilingFan ceilingFan;
+    int prevSpeed;
+
+    this(CeilingFan ceilingFan)
+    {
+        this.ceilingFan = ceilingFan;
+    }
+
+    void execute()
+    {
+        prevSpeed = ceilingFan.getSpeed();
+        ceilingFan.medium();
+    }
+
+    void undo()
+    {
+        switch (prevSpeed)
+        {
+            case CeilingFan.HIGH:
+                ceilingFan.high();
+                break;
+            case CeilingFan.MEDIUM:
+                ceilingFan.medium();
+                break;
+            case CeilingFan.LOW:
+                ceilingFan.low();
+                break;
+            case CeilingFan.OFF:
+                ceilingFan.off();
+                break;
+            default: break;
+        }
+    }
+}
diff --git a/command/remoteundostatus/ceilingfanoffcommand.d b/command/remoteundostatus/ceilingfanoffcommand.d
new file mode 100644
index 0000000..3e5e174
--- /dev/null
+++ b/command/remoteundostatus/ceilingfanoffcommand.d
@@ -0,0 +1,41 @@
+module command.remoteundostatus.ceilingfanoffcommand;
+
+import command.remoteundostatus.command;
+import command.remoteundostatus.ceilingfan;
+
+class CeilingFanOffCommand : Command
+{
+    CeilingFan ceilingFan;
+    int prevSpeed;
+
+    this(CeilingFan ceilingFan)
+    {
+        this.ceilingFan = ceilingFan;
+    }
+
+    void execute()
+    {
+        prevSpeed = ceilingFan.getSpeed();
+        ceilingFan.off();
+    }
+
+    void undo()
+    {
+        switch (prevSpeed)
+        {
+            case CeilingFan.HIGH:
+                ceilingFan.high();
+                break;
+            case CeilingFan.MEDIUM:
+                ceilingFan.medium();
+                break;
+            case CeilingFan.LOW:
+                ceilingFan.low();
+                break;
+            case CeilingFan.OFF:
+                ceilingFan.off();
+                break;
+            default: break;
+        }
+    }
+}
diff --git a/command/remoteundostatus/command.d b/command/remoteundostatus/command.d
new file mode 100644
index 0000000..a1945ae
--- /dev/null
+++ b/command/remoteundostatus/command.d
@@ -0,0 +1,7 @@
+module command.remoteundostatus.command;
+
+interface Command
+{
+    void execute();
+    void undo();
+}
diff --git a/command/remoteundostatus/garagedoor.d b/command/remoteundostatus/garagedoor.d
new file mode 100644
index 0000000..1bf9ac5
--- /dev/null
+++ b/command/remoteundostatus/garagedoor.d
@@ -0,0 +1,38 @@
+module command.remoteundostatus.garagedoor;
+
+import std.stdio : writeln;
+
+class GarageDoor
+{
+    private string location;
+
+    this(string location)
+    {
+        this.location = location;
+    }
+
+    void up()
+    {
+        writeln(location ~ " garage Door is Up");
+    }
+
+    void down()
+    {
+        writeln(location ~ " garage Door is Down");
+    }
+
+    void stop()
+    {
+        writeln(location ~ " garage Door is Stopped");
+    }
+
+    void lightOn()
+    {
+        writeln(location ~ " garage light is on");
+    }
+
+    void lightOff()
+    {
+        writeln(location ~ " garage light is off");
+    }
+}
diff --git a/command/remoteundostatus/garagedoordowncommand.d b/command/remoteundostatus/garagedoordowncommand.d
new file mode 100644
index 0000000..c47de33
--- /dev/null
+++ b/command/remoteundostatus/garagedoordowncommand.d
@@ -0,0 +1,24 @@
+module command.remoteundostatus.garagedoordowncommand;
+
+import command.remoteundostatus.command;
+import command.remoteundostatus.garagedoor;
+
+class GarageDoorDownCommand : Command
+{
+    GarageDoor garageDoor;
+
+    this(GarageDoor garageDoor)
+    {
+        this.garageDoor = garageDoor;
+    }
+
+    void execute()
+    {
+        garageDoor.down();
+    }
+
+    void undo()
+    {
+        garageDoor.up();
+    }
+}
diff --git a/command/remoteundostatus/garagedoorupcommand.d b/command/remoteundostatus/garagedoorupcommand.d
new file mode 100644
index 0000000..5f865bb
--- /dev/null
+++ b/command/remoteundostatus/garagedoorupcommand.d
@@ -0,0 +1,24 @@
+module command.remoteundostatus.garagedoorupcommand;
+
+import command.remoteundostatus.command;
+import command.remoteundostatus.garagedoor;
+
+class GarageDoorUpCommand : Command
+{
+    GarageDoor garageDoor;
+
+    this(GarageDoor garageDoor)
+    {
+        this.garageDoor = garageDoor;
+    }
+
+    void execute()
+    {
+        garageDoor.up();
+    }
+
+    void undo()
+    {
+        garageDoor.down();
+    }
+}
diff --git a/command/remoteundostatus/light.d b/command/remoteundostatus/light.d
new file mode 100644
index 0000000..aa0cf4e
--- /dev/null
+++ b/command/remoteundostatus/light.d
@@ -0,0 +1,23 @@
+module command.remoteundostatus.light;
+
+import std.stdio : writeln;
+
+class Light
+{
+    private string location;
+
+    this(string location)
+    {
+        this.location = location;
+    }
+
+    void on()
+    {
+        writeln(location ~ " light is On");
+    }
+
+    void off()
+    {
+        writeln(location ~ " light is Off");
+    }
+}
diff --git a/command/remoteundostatus/lightoffcommand.d b/command/remoteundostatus/lightoffcommand.d
new file mode 100644
index 0000000..c66f98b
--- /dev/null
+++ b/command/remoteundostatus/lightoffcommand.d
@@ -0,0 +1,24 @@
+module command.remoteundostatus.lightoffcommand;
+
+import command.remoteundostatus.command;
+import command.remoteundostatus.light;
+
+class LightOffCommand : Command
+{
+    Light light;
+
+    this(Light light)
+    {
+        this.light = light;
+    }
+
+    void execute()
+    {
+        light.off();
+    }
+
+    void undo()
+    {
+        light.on();
+    }
+}
diff --git a/command/remoteundostatus/lightoncommand.d b/command/remoteundostatus/lightoncommand.d
new file mode 100644
index 0000000..24619ea
--- /dev/null
+++ b/command/remoteundostatus/lightoncommand.d
@@ -0,0 +1,24 @@
+module command.remoteundostatus.lightoncommand;
+
+import command.remoteundostatus.command;
+import command.remoteundostatus.light;
+
+class LightOnCommand : Command
+{
+    Light light;
+
+    this(Light light)
+    {
+        this.light = light;
+    }
+
+    void execute()
+    {
+        light.on();
+    }
+
+    void undo()
+    {
+        light.off();
+    }
+}
diff --git a/command/remoteundostatus/nocommand.d b/command/remoteundostatus/nocommand.d
new file mode 100644
index 0000000..8f81974
--- /dev/null
+++ b/command/remoteundostatus/nocommand.d
@@ -0,0 +1,9 @@
+module command.remoteundostatus.nocommand;
+
+import command.remoteundostatus.command;
+
+class NoCommand : Command
+{
+    void execute() {}
+    void undo() {}
+}
diff --git a/command/remoteundostatus/remotecontrol.d b/command/remoteundostatus/remotecontrol.d
new file mode 100644
index 0000000..2366274
--- /dev/null
+++ b/command/remoteundostatus/remotecontrol.d
@@ -0,0 +1,63 @@
+module command.remoteundostatus.remotecontrol;
+
+import command.remoteundostatus.command;
+import command.remoteundostatus.nocommand;
+import std.conv : to;
+import std.stdio : writeln;
+import std.algorithm.mutation : fill;
+import std.array : split, back;
+import std.format;
+
+class RemoteControl
+{
+    Command[] onCommands;
+    Command[] offCommands;
+    Command undoCommand;
+
+    this()
+    {
+        onCommands = new Command[7];
+        offCommands = new Command[7];
+        Command noCommand = new NoCommand();
+        fill(onCommands, noCommand);        
+        fill(offCommands, noCommand);
+        undoCommand = noCommand;
+    }
+
+    void setCommand(int slot, Command onCommand, Command offCommand)
+    {
+        onCommands[slot] = onCommand;
+        offCommands[slot] = offCommand;
+    }
+
+    void onButtonWasPushed(int slot)
+    {
+        onCommands[slot].execute();
+        undoCommand = onCommands[slot];
+    }
+
+    void offButtonWasPushed(int slot)
+    {
+        offCommands[slot].execute();
+        undoCommand = offCommands[slot];
+    }
+
+    void undoButtonWasPushed()
+    {
+        undoCommand.undo();
+    }
+
+    override string toString() const
+    {
+        string s = "\n------ Remote Control -------\n";
+        for (int i = 0; i < 7; ++i)
+        {
+            s ~= "[slot " ~ i.to!string ~ "] "
+                ~ format("%23s", (cast(Object)onCommands[i]).classinfo.name.split(".").back())
+                ~ format("%23s", (cast(Object)offCommands[i]).classinfo.name.split(".").back())
+                ~ "\n";
+        }
+
+        return s ~ "[undo] " ~ (cast(Object)undoCommand).classinfo.name.split(".").back() ~ "\n";
+    }
+}
diff --git a/command/remoteundostatus/stereo.d b/command/remoteundostatus/stereo.d
new file mode 100644
index 0000000..09d7cf9
--- /dev/null
+++ b/command/remoteundostatus/stereo.d
@@ -0,0 +1,44 @@
+module command.remoteundostatus.stereo;
+
+import std.stdio : writeln;
+import std.conv : to;
+
+class Stereo
+{
+    string location;
+
+    this(string location)
+    {
+        this.location = location;
+    }
+
+    void on()
+    {
+        writeln(location ~ " stereo is on");
+    }
+
+    void off()
+    {
+        writeln(location ~ " stereo is off");
+    }
+
+    void setCD()
+    {
+        writeln(location ~ " stereo is set for CD input");
+    }
+
+    void setDVD()
+    {
+        writeln(location ~ " stereo is set for DVD input");
+    }
+
+    void setRadio()
+    {
+        writeln(location ~ " stereo is set for Radio");
+    }
+
+    void setVolume(int volume)
+    {
+        writeln(location ~ " stereo volume set to " ~ volume.to!string);
+    }
+}
diff --git a/command/remoteundostatus/stereooffcommand.d b/command/remoteundostatus/stereooffcommand.d
new file mode 100644
index 0000000..b1a5fed
--- /dev/null
+++ b/command/remoteundostatus/stereooffcommand.d
@@ -0,0 +1,26 @@
+module command.remoteundostatus.stereooffcommand;
+
+import command.remoteundostatus.command;
+import command.remoteundostatus.stereo;
+
+class StereoOffCommand : Command
+{
+    Stereo stereo;
+ 
+    this(Stereo stereo)
+    {
+        this.stereo = stereo;
+    }
+ 
+    void execute()
+    {
+        stereo.off();
+    }
+
+    void undo()
+    {
+        stereo.on();
+        stereo.setCD();
+        stereo.setVolume(11);
+    }
+}
diff --git a/command/remoteundostatus/stereoonwithcdcommand.d b/command/remoteundostatus/stereoonwithcdcommand.d
new file mode 100644
index 0000000..b69353b
--- /dev/null
+++ b/command/remoteundostatus/stereoonwithcdcommand.d
@@ -0,0 +1,26 @@
+module command.remoteundostatus.stereoonwithcdcommand;
+
+import command.remoteundostatus.command;
+import command.remoteundostatus.stereo;
+
+class StereoOnWithCDCommand : Command
+{
+    Stereo stereo;
+ 
+    this(Stereo stereo)
+    {
+        this.stereo = stereo;
+    }
+ 
+    void execute()
+    {
+        stereo.on();
+        stereo.setCD();
+        stereo.setVolume(11);
+    }
+
+    void undo()
+    {
+        stereo.off();
+    }
+}