1 files changed, 45 insertions, 0 deletions
diff --git a/src/main/ui/UIHandler.java b/src/main/ui/UIHandler.java
new file mode 100644
index 0000000..f451542
--- /dev/null
+++ b/src/main/ui/UIHandler.java
@@ -0,0 +1,45 @@
+package ui;
+
+/**
+ * Represents a screen
+ */
+public interface UIHandler {
+    /**
+     * EFFECTS: Called when the screen is switched to.
+     */
+    default void enter(Object... args) {
+
+    }
+
+    /**
+     * EFFECTS: Show objects. command() will not be called.
+     */
+    void show();
+
+    /**
+     * EFFECTS: Commit changes and exit. command() will not be called.
+     */
+    default void commit() {
+    }
+
+    /**
+     * EFFECTS: Discard changes and exit. command() will not be called. Returns the next screen.
+     */
+    Screen exit();
+
+    /**
+     * EFFECTS: Run help. command() will not be called.
+     */
+    void help();
+
+    /**
+     * EFFECTS: Any commands rather than commit / exit / help.
+     * REQUIRES: args != null && args.length >= 1
+     */
+    void command(String... args);
+
+    /**
+     * EFFECTS: Return the current PS1 prompt.
+     */
+    String getPS1();
+}