Implement the hunger system

src/hunger_system.rs

@@ -0,0 +1,82 @@
+use crate::components::{HungerClock, HungerState, SufferDamage};
+use crate::{game_log::GameLog, RunState};
+use specs::prelude::*;
+
+pub struct HungerSystem {}
+
+impl<'a> System<'a> for HungerSystem {
+    #[allow(clippy::type_complexity)]
+    type SystemData = (
+        Entities<'a>,
+        WriteStorage<'a, HungerClock>,
+        ReadExpect<'a, Entity>, // The player
+        ReadExpect<'a, RunState>,
+        WriteStorage<'a, SufferDamage>,
+        WriteExpect<'a, GameLog>,
+    );
+
+    fn run(&mut self, data: Self::SystemData) {
+        let (entities, mut hunger_clock, player_entity, runstate, mut inflict_damage, mut log) =
+            data;
+
+        for (entity, mut clock) in (&entities, &mut hunger_clock).join() {
+            let mut proceed = false;
+
+            match *runstate {
+                RunState::PlayerTurn => {
+                    if entity == *player_entity {
+                        proceed = true;
+                    }
+                }
+                RunState::MonsterTurn => {
+                    if entity != *player_entity {
+                        proceed = true;
+                    }
+                }
+                _ => proceed = false,
+            }
+
+            if proceed {
+                clock.duration -= 1;
+
+                if clock.duration < 1 {
+                    match clock.state {
+                        HungerState::WellFed => {
+                            clock.state = HungerState::Normal;
+                            clock.duration = 200;
+
+                            if entity == *player_entity {
+                                log.entries.push("You are no longer well fed.".to_string());
+                            }
+                        }
+                        HungerState::Normal => {
+                            clock.state = HungerState::Hungry;
+                            clock.duration = 200;
+
+                            if entity == *player_entity {
+                                log.entries.push("You are hungry.".to_string());
+                            }
+                        }
+                        HungerState::Hungry => {
+                            clock.state = HungerState::Starving;
+                            clock.duration = 200;
+
+                            if entity == *player_entity {
+                                log.entries.push("You are starving!".to_string());
+                            }
+                        }
+                        HungerState::Starving => {
+                            // Inflict damage from hunger
+                            if entity == *player_entity {
+                                log.entries
+                                    .push("Your hunger pangs are getting painful!".to_string());
+                            }
+
+                            SufferDamage::new_damage(&mut inflict_damage, entity, 1);
+                        }
+                    }
+                }
+            }
+        }
+    }
+}

src/main.rs

@@ -6,6 +6,7 @@ mod components;
 mod damage_system;
 mod game_log;
 mod gui;
+mod hunger_system;
 mod inventory_system;
 mod map;
 mod map_indexing_system;
@@ -101,6 +102,9 @@ impl State {
         let mut item_remove = ItemRemoveSystem {};
         item_remove.run_now(&self.ecs);
 
+        let mut hunger = hunger_system::HungerSystem {};
+        hunger.run_now(&self.ecs);
+
         let mut particles = particle_system::ParticleSpawnSystem {};
         particles.run_now(&self.ecs);