movement depends on monster class now

src/level.rs

@@ -129,13 +129,7 @@ impl Level {
             }
             loop {
                 // calculate the direction the monster will try to walk
-                let (dx, dy) = match self.rng.gen_range(0..5) {
+                let (dx, dy) = self.monsters[index].get_next_move(&self, player.get_immutable_position());
-                    1 => { (1, 0) }
-                    2 => { (-1, 0) }
-                    3 => { (0, 1) }
-                    4 => { (0, -1) }
-                    _ => { (0, 0) }
-                };
                 if self.can_monster_move(self.monsters[index].as_ref(), dx, dy) {
                     let (new_x, new_y) = self.monsters[index].get_position().change(dx, dy);
                     if player.get_immutable_position().get_x() == new_x && player.get_immutable_position().get_y() == new_y {

src/monster.rs

@@ -1,7 +1,10 @@
 use ratatui::prelude::Color;
 
 use crate::dungeon_slayer::MonsterStats;
+use crate::level::Level;
 use crate::position::{HasPosition, Position};
+use rand::Rng;
+
 
 pub trait Monster: HasPosition {
     fn get_name(&self) -> &str;
@@ -13,6 +16,7 @@ pub trait Monster: HasPosition {
     fn get_ticks_between_steps(&self) -> u128;
     fn get_defense(&self) -> u8;
     fn get_hit(&self) -> u8;
+    fn get_next_move(&self, level: &Level, player_pos: &Position) -> (i16, i16);
     #[cfg(test)]
     fn get_life(&self) -> usize;
 }
@@ -30,6 +34,9 @@ macro_rules! default_monster {
             fn get_ticks_between_steps(&self) -> u128 { self.ticks_between_steps }
             fn get_defense(&self) -> u8 { self.monster_stats.defense }
             fn get_hit(&self) -> u8 { self.monster_stats.hit }
+            fn get_next_move(&self, level: &Level, player_pos: &Position) -> (i16, i16) {
+                self.calc_move(level, player_pos)
+            }
             #[cfg(test)]
             fn get_life(&self) -> usize { self.life }
         }
@@ -90,6 +97,20 @@ impl crate::monster::LowerDaemon {
             monster_stats,
         }
     }
+
+    fn calc_move(&self, level: &Level, player_pos: &Position) -> (i16, i16) {
+        let d = self.position.distance(player_pos);
+        if d == 1 {
+            return self.position.get_direction(player_pos);
+        }
+        match rand::thread_rng().gen_range(0..5) {
+            1 => { (1, 0) }
+            2 => { (-1, 0) }
+            3 => { (0, 1) }
+            4 => { (0, -1) }
+            _ => { (0, 0) }
+        }
+    }
 }
 default_monster!(LowerDaemon);
 
@@ -139,6 +160,15 @@ impl Rat {
             monster_stats,
         }
     }
+    fn calc_move(&self, level: &Level, player_pos: &Position) -> (i16, i16) {
+        match rand::thread_rng().gen_range(0..5) {
+            1 => { (1, 0) }
+            2 => { (-1, 0) }
+            3 => { (0, 1) }
+            4 => { (0, -1) }
+            _ => { (0, 0) }
+        }
+    }
 }
 default_monster!(Rat);
 
@@ -188,6 +218,15 @@ impl Orc {
             monster_stats,
         }
     }
+    fn calc_move(&self, level: &Level, player_pos: &Position) -> (i16, i16) {
+        match rand::thread_rng().gen_range(0..5) {
+            1 => { (1, 0) }
+            2 => { (-1, 0) }
+            3 => { (0, 1) }
+            4 => { (0, -1) }
+            _ => { (0, 0) }
+        }
+    }
 }
 
 default_monster!(Orc);

src/position.rs

@@ -1,4 +1,4 @@
-use std::cmp::max;
+use std::cmp::{max, min};
 
 /// describes an character (PC or NPC) in the dungeon that has a position.
 pub trait HasPosition {
@@ -43,6 +43,28 @@ impl Position {
     }
 
     pub fn get_y(&self) -> usize { self.y }
+
+    /// calculate the distance to the other position using the manhattan metric
+    pub fn distance(&self, other: &Self) -> usize {
+        self.x.abs_diff(other.x) + self.y.abs_diff(other.y)
+    }
+
+    /// get the direction (step size 1) towards the other position
+    pub fn get_direction(&self, other: &Self) -> (i16, i16) {
+        (
+            max(min(other.x as i16 - self.x as i16, 1), -1),
+            max(min(other.y as i16 - self.y as i16, 1), -1)
+        )
+    }
+}
+
+#[test]
+fn test_get_direction() {
+    let p1 = Position::new(0, 10, 10);
+    let p2 = Position::new(0, 8, 8);
+    assert_eq!(p1.get_direction(&p2), (-1, -1));
+    let p2 = Position::new(0, 11, 10);
+    assert_eq!(p1.get_direction(&p2), (1, 0));
 }
 
 #[test]