Provide an API for registering custom APIs

src/main/java/dan200/computercraft/ComputerCraft.java

@@ -9,6 +9,7 @@
 import com.google.common.base.CaseFormat;
 import dan200.computercraft.api.filesystem.IMount;
 import dan200.computercraft.api.filesystem.IWritableMount;
+import dan200.computercraft.api.lua.ILuaAPIFactory;
 import dan200.computercraft.api.media.IMedia;
 import dan200.computercraft.api.media.IMediaProvider;
 import dan200.computercraft.api.network.IPacketNetwork;
@@ -81,10 +82,7 @@
 import java.net.MalformedURLException;
 import java.net.URISyntaxException;
 import java.net.URL;
-import java.util.ArrayList;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
+import java.util.*;
 import java.util.zip.ZipEntry;
 import java.util.zip.ZipFile;
 
@@ -244,6 +242,7 @@ public static class Config {
     private static List<IMediaProvider> mediaProviders = new ArrayList<>();
     private static List<ITurtlePermissionProvider> permissionProviders = new ArrayList<>();
     private static final Map<String, IPocketUpgrade> pocketUpgrades = new HashMap<>();
+    private static final Set<ILuaAPIFactory> apiFactories = new LinkedHashSet<>();
 
     // Implementation
     @Mod.Instance( value = ComputerCraft.MOD_ID )
@@ -644,6 +643,14 @@ public static void registerMediaProvider( IMediaProvider provider )
         }
     }
 
+    public static void registerAPIFactory( ILuaAPIFactory provider )
+    {
+        if( provider != null )
+        {
+            apiFactories.add( provider );
+        }
+    }
+
     public static IPeripheral getPeripheralAt( World world, BlockPos pos, EnumFacing side )
     {
         // Try the handlers in order:
@@ -771,6 +778,11 @@ public IPacketNetwork getWirelessNetwork()
         return WirelessNetwork.getUniversal();
     }
 
+    public static Iterable<ILuaAPIFactory> getAPIFactories()
+    {
+        return apiFactories;
+    }
+
     public static int createUniqueNumberedSaveDir( World world, String parentSubPath )
     {
         return IDAssigner.getNextIDFromDirectory(new File(getWorldDir(world), parentSubPath));

src/main/java/dan200/computercraft/api/ComputerCraftAPI.java

@@ -8,6 +8,7 @@
 
 import dan200.computercraft.api.filesystem.IMount;
 import dan200.computercraft.api.filesystem.IWritableMount;
+import dan200.computercraft.api.lua.ILuaAPIFactory;
 import dan200.computercraft.api.media.IMedia;
 import dan200.computercraft.api.media.IMediaProvider;
 import dan200.computercraft.api.network.IPacketNetwork;
@@ -311,6 +312,22 @@ public static IPacketNetwork getWirelessNetwork()
         return null;
     }
 
+    public static void registerAPIFactory( @Nonnull ILuaAPIFactory upgrade )
+    {
+        findCC();
+        if( computerCraft_registerAPIFactory != null )
+        {
+            try
+            {
+                computerCraft_registerAPIFactory.invoke( null, upgrade );
+            }
+            catch( Exception e )
+            {
+                // It failed
+            }
+        }
+    }
+
     // The functions below here are private, and are used to interface with the non-API ComputerCraft classes.
     // Reflection is used here so you can develop your mod without decompiling ComputerCraft and including
     // it in your solution, and so your mod won't crash if ComputerCraft is installed.
@@ -354,6 +371,9 @@ private static void findCC()
                 } );
                 computerCraft_getWirelessNetwork = findCCMethod( "getWirelessNetwork", new Class<?>[] {
                 } );
+                computerCraft_registerAPIFactory = findCCMethod( "registerAPIFactory", new Class<?>[] {
+                    ILuaAPIFactory.class
+                } );
             } catch( Exception e ) {
                 System.out.println( "ComputerCraftAPI: ComputerCraft not found." );
             } finally {
@@ -390,4 +410,5 @@ private static Method findCCMethod( String name, Class<?>[] args )
     private static Method computerCraft_registerPermissionProvider = null;
     private static Method computerCraft_registerPocketUpgrade = null;
     private static Method computerCraft_getWirelessNetwork = null;
+    private static Method computerCraft_registerAPIFactory = null;
 }

src/main/java/dan200/computercraft/api/filesystem/IFileSystem.java

@@ -0,0 +1,38 @@
+package dan200.computercraft.api.filesystem;
+
+import java.io.IOException;
+
+/**
+ * Provides a mount of the entire computer's file system.
+ *
+ * This exists for use by various APIs - one should not attempt to mount it.
+ */
+public interface IFileSystem extends IWritableMount
+{
+    /**
+     * Combine two paths together, reducing them into a normalised form.
+     *
+     * @param path  The main path.
+     * @param child The path to append.
+     * @return The combined, normalised path.
+     */
+    String combine( String path, String child );
+
+    /**
+     * Copy files from one location to another.
+     *
+     * @param from The location to copy from.
+     * @param to   The location to copy to. This should not exist.
+     * @throws IOException If the copy failed.
+     */
+    void copy( String from, String to ) throws IOException;
+
+    /**
+     * Move files from one location to another.
+     *
+     * @param from The location to move from.
+     * @param to   The location to move to. This should not exist.
+     * @throws IOException If the move failed.
+     */
+    void move( String from, String to ) throws IOException;
+}

src/main/java/dan200/computercraft/api/lua/IComputerSystem.java

@@ -0,0 +1,29 @@
+package dan200.computercraft.api.lua;
+
+import dan200.computercraft.api.filesystem.IFileSystem;
+import dan200.computercraft.api.peripheral.IComputerAccess;
+
+import javax.annotation.Nullable;
+
+/**
+ * An interface passed to {@link ILuaAPIFactory} in order to provide additional information
+ * about a computer.
+ */
+public interface IComputerSystem extends IComputerAccess
+{
+    /**
+     * Get the file system for this computer.
+     *
+     * @return The computer's file system, or {@code null} if it is not initialised.
+     */
+    @Nullable
+    IFileSystem getFileSystem();
+
+    /**
+     * Get the label for this computer
+     *
+     * @return This computer's label, or {@code null} if it is not set.
+     */
+    @Nullable
+    String getLabel();
+}

src/main/java/dan200/computercraft/api/lua/ILuaAPI.java

@@ -0,0 +1,47 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2016. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+
+package dan200.computercraft.api.lua;
+
+import dan200.computercraft.api.ComputerCraftAPI;
+
+/**
+ * Represents a {@link ILuaObject} which is stored as a global variable on computer startup.
+ *
+ * Before implementing this interface, consider alternative methods of providing methods. It is generally preferred
+ * to use peripherals to provide functionality to users.
+ *
+ * @see ILuaAPIFactory
+ * @see ComputerCraftAPI#registerAPIFactory(ILuaAPIFactory)
+ */
+public interface ILuaAPI extends ILuaObject
+{
+    /**
+     * Get the globals this API will be assigned to. This will override any other global, so you should
+     *
+     * @return A list of globals this API will be assigned to.
+     */
+    String[] getNames();
+
+    /**
+     * Called when the computer is turned on.
+     *
+     * One should only interact with the file system.
+     */
+    default void startup() { }
+
+    /**
+     * Called every time the computer is ticked. This can be used to process various.
+     */
+    default void update() { }
+
+    /**
+     * Called when the computer is turned off or unloaded.
+     *
+     * This should reset the state of the object, disposing any remaining file handles, or other resources.
+     */
+    default void shutdown() { }
+}

src/main/java/dan200/computercraft/api/lua/ILuaAPIFactory.java

@@ -0,0 +1,24 @@
+package dan200.computercraft.api.lua;
+
+import dan200.computercraft.api.ComputerCraftAPI;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
+/**
+ * Construct an {@link ILuaAPI} for a specific computer.
+ *
+ * @see ILuaAPI
+ * @see ComputerCraftAPI#registerAPIFactory(ILuaAPIFactory)
+ */
+public interface ILuaAPIFactory
+{
+    /**
+     * Create a new API instance for a given computer.
+     *
+     * @param computer The computer this API is for.
+     * @return The created API, or {@code null} if one should not be injected.
+     */
+    @Nullable
+    ILuaAPI create( @Nonnull IComputerSystem computer );
+}

src/main/java/dan200/computercraft/core/apis/BitAPI.java

@@ -6,6 +6,7 @@
 
 package dan200.computercraft.core.apis;
 
+import dan200.computercraft.api.lua.ILuaAPI;
 import dan200.computercraft.api.lua.ILuaContext;
 import dan200.computercraft.api.lua.LuaException;
 
@@ -37,21 +38,6 @@ public String[] getNames()
             "bit"
         };
     }
-
-    @Override
-    public void startup( )
-    {
-    }
-
-    @Override
-    public void advance( double _dt )
-    {
-    }
-
-    @Override
-    public void shutdown( )
-    {
-    }
 
     @Nonnull
     @Override

src/main/java/dan200/computercraft/core/apis/BufferAPI.java

@@ -6,6 +6,7 @@
 
 package dan200.computercraft.core.apis;
 
+import dan200.computercraft.api.lua.ILuaAPI;
 import dan200.computercraft.api.lua.ILuaContext;
 import dan200.computercraft.api.lua.ILuaObject;
 import dan200.computercraft.api.lua.LuaException;
@@ -100,21 +101,6 @@ public String[] getNames()
         };
     }
 
-    @Override
-    public void startup()
-    {
-    }
-
-    @Override
-    public void advance( double _dt )
-    {
-    }
-
-    @Override
-    public void shutdown()
-    {
-    }
-
     @Nonnull
     @Override
     public String[] getMethodNames()