Add containers for various run-time options.

diff --git a/src/main/java/net/pterodactylus/sone/core/Options.java b/src/main/java/net/pterodactylus/sone/core/Options.java
new file mode 100644 (file)
index 0000000..04010da
--- /dev/null
+++ b/src/main/java/net/pterodactylus/sone/core/Options.java
@@ -0,0 +1,181 @@
+package net.pterodactylus.sone.core;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Stores various options that influence Sone’s behaviour.
+ *
+ * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+ */
+public class Options {
+
+       /**
+        * Contains current and default value of an option.
+        *
+        * @param <T>
+        *            The type of the option
+        * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+        */
+       public static interface Option<T> {
+
+               /**
+                * Returns the default value of the option.
+                *
+                * @return The default value of the option
+                */
+               public T getDefault();
+
+               /**
+                * Returns the current value of the option. If the current value is not
+                * set (usually {@code null}), the default value is returned.
+                *
+                * @return The current value of the option
+                */
+               public T get();
+
+               /**
+                * Returns the real value of the option. This will also return an unset
+                * value (usually {@code null})!
+                *
+                * @return The real value of the option
+                */
+               public T getReal();
+
+               /**
+                * Sets the current value of the option.
+                *
+                * @param value
+                *            The new value of the option
+                */
+               public void set(T value);
+
+       }
+
+       /**
+        * Interface for objects that want to be notified when an option changes its
+        * value.
+        *
+        * @param <T>
+        *            The type of the option
+        * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+        */
+       public static interface OptionWatcher<T> {
+
+               /**
+                * Notifies an object that an option has been changed.
+                *
+                * @param option
+                *            The option that has changed
+                * @param oldValue
+                *            The old value of the option
+                * @param newValue
+                *            The new value of the option
+                */
+               public void optionChanged(Option<T> option, T oldValue, T newValue);
+
+       }
+
+       /**
+        * Basic implementation of an {@link Option} that notifies an
+        * {@link OptionWatcher} if the value changes.
+        *
+        * @param <T>
+        *            The type of the option
+        * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+        */
+       public static class DefaultOption<T> implements Option<T> {
+
+               /** The default value. */
+               private final T defaultValue;
+
+               /** The current value. */
+               private T value;
+
+               /** The option watcher. */
+               private final OptionWatcher<T> optionWatcher;
+
+               /**
+                * Creates a new default option.
+                *
+                * @param defaultValue
+                *            The default value of the option
+                * @param optionWatcher
+                *            The option watcher
+                */
+               public DefaultOption(T defaultValue, OptionWatcher<T> optionWatcher) {
+                       this.defaultValue = defaultValue;
+                       this.optionWatcher = optionWatcher;
+               }
+
+               /**
+                * {@inheritDoc}
+                */
+               @Override
+               public T getDefault() {
+                       return defaultValue;
+               }
+
+               /**
+                * {@inheritDoc}
+                */
+               @Override
+               public T get() {
+                       return (value != null) ? value : defaultValue;
+               }
+
+               /**
+                * Returns the real value of the option. This will also return an unset
+                * value (usually {@code null})!
+                *
+                * @return The real value of the option
+                */
+               @Override
+               public T getReal() {
+                       return value;
+               }
+
+               /**
+                * {@inheritDoc}
+                */
+               @Override
+               public void set(T value) {
+                       T oldValue = this.value;
+                       this.value = value;
+                       if (!get().equals(oldValue)) {
+                               optionWatcher.optionChanged(this, oldValue, get());
+                       }
+               }
+
+       }
+
+       /** Holds all {@link Integer} {@link Option}s. */
+       private final Map<String, Option<Integer>> integerOptions = new HashMap<String, Option<Integer>>();
+
+       /**
+        * Adds an {@link Integer} {@link Option}.
+        *
+        * @param name
+        *            The name of the option
+        * @param integerOption
+        *            The option
+        * @return The given option
+        */
+       public Option<Integer> addIntegerOption(String name, Option<Integer> integerOption) {
+               integerOptions.put(name, integerOption);
+               return integerOption;
+       }
+
+       /**
+        * Returns an {@link Integer} {@link Option}.
+        *
+        * @param name
+        *            The name of the integer option to get
+        * @return The integer option, or {@code null} if there is no option with
+        *         the given name
+        */
+       public Option<Integer> getIntegerOption(String name) {
+               return integerOptions.get(name);
+       }
+
+}