From bebd9d617e472886b20fcdc635b2ee5c6a8fcc13 Mon Sep 17 00:00:00 2001
From: Timothy Warren <twarren@nabancard.com>
Date: Thu, 13 Jan 2022 15:37:06 -0500
Subject: [PATCH] Add cursor mode to look around using keyboard controls

---
 input_handlers.py | 71 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)

diff --git a/input_handlers.py b/input_handlers.py
index 11db90b..99e1a10 100644
--- a/input_handlers.py
+++ b/input_handlers.py
@@ -56,6 +56,11 @@ WAIT_KEYS = {
     tcod.event.K_CLEAR,
 }
 
+CONFIRM_KEYS = {
+    tcod.event.K_RETURN,
+    tcod.event.K_KP_ENTER,
+}
+
 
 class EventHandler(tcod.event.EventDispatch[Action]):
     def __init__(self, engine: Engine):
@@ -225,6 +230,70 @@ class InventoryDropHandler(InventoryEventHandler):
         return actions.DropItem(self.engine.player, item)
 
 
+class SelectIndexHandler(AskUserEventHandler):
+    """Handles asking the user for an index on the map."""
+
+    def __init__(self, engine: Engine):
+        """Sets the cursor to the player when this handler is constructed."""
+        super().__init__(engine)
+        player = self.engine.player
+        engine.mouse_location = player.x, player.y
+
+    def on_render(self, console: tcod.Console) -> None:
+        """Highlight the tile under the cursor."""
+        super().on_render(console)
+        x, y = self.engine.mouse_location
+        console.tiles_rgb["bg"][x, y] = color.white
+        console.tiles_rgb["fg"][x, y] = color.black
+
+    def ev_keydown(self, event: tcod.event.KeyDown) -> Optional[Action]:
+        """Check for key movement or confirmation keys."""
+        key = event.sym
+        if key in MOVE_KEYS:
+            modifier = 1  # Holding modifier keys will speed up key movement
+            if event.mod & (tcod.event.KMOD_LSHIFT | tcod.event.KMOD_RSHIFT):
+                modifier *= 5
+            if event.mod & (tcod.event.KMOD_LCTRL | tcod.event.KMOD_RCTRL):
+                modifier *= 10
+            if event.mod & (tcod.event.KMOD_LALT | tcod.event.KMOD_RALT):
+                modifier *= 20
+
+            x, y = self.engine.mouse_location
+            dx, dy = MOVE_KEYS[key]
+            x += dx * modifier
+            y += dy * modifier
+            # Clamp the cursor index to the map size.
+            x = max(0, min(x, self.engine.game_map.width - 1))
+            y = max(0, min(y, self.engine.game_map.height - 1))
+            self.engine.mouse_location = x, y
+
+            return None
+        elif key in CONFIRM_KEYS:
+            return self.on_index_selected(*self.engine.mouse_location)
+
+        return super().ev_keydown(event)
+
+    def ev_mousebuttondown(self, event: tcod.event.MouseButtonDown) -> Optional[Action]:
+        """Left click confirms a selection."""
+        if self.engine.game_map.in_bounds(*event.tile):
+            if event.button == 1:
+                return self.on_index_selected(*event.tile)
+
+        return super().ev_mousebuttondown(event)
+
+    @overload
+    def on_index_selected(self, x: int, y: int) -> Optional[Action]:
+        """Called when an index is selected."""
+
+
+class LookHandler(SelectIndexHandler):
+    """Lets the player look around using the keyboard."""
+
+    def on_index_selected(self, x: int, y: int) -> None:
+        """Return to main handler."""
+        self.engine.event_handler = MainGameEventHandler(self.engine)
+
+
 class MainGameEventHandler(EventHandler):
     def ev_keydown(self, event: tcod.event.KeyDown) -> Optional[Action]:
         action: Optional[Action] = None
@@ -252,6 +321,8 @@ class MainGameEventHandler(EventHandler):
             self.engine.event_handler = InventoryActivateHandler(self.engine)
         elif key == tcod.event.K_d:
             self.engine.event_handler = InventoryDropHandler(self.engine)
+        elif key == tcod.event.K_SLASH:
+            self.engine.event_handler = LookHandler(self.engine)
 
         # No valid key was pressed
         return action