Allow drinking of potions

src/components.rs

@@ -85,3 +85,8 @@ pub struct WantsToPickupItem {
     pub collected_by: Entity,
     pub item: Entity,
 }
+
+#[derive(Component, Debug)]
+pub struct WantsToDrinkPotion {
+    pub potion: Entity,
+}

src/gui.rs

@@ -161,10 +161,11 @@ pub enum ItemMenuResult {
     Selected,
 }
 
-pub fn show_inventory(gs: &mut State, ctx: &mut Rltk) -> ItemMenuResult {
+pub fn show_inventory(gs: &mut State, ctx: &mut Rltk) -> (ItemMenuResult, Option<Entity>) {
     let player_entity = gs.ecs.fetch::<Entity>();
     let names = gs.ecs.read_storage::<Name>();
     let backpack = gs.ecs.read_storage::<InBackpack>();
+    let entities = gs.ecs.entities();
 
     let inventory = (&backpack, &names)
         .join()
@@ -195,10 +196,11 @@ pub fn show_inventory(gs: &mut State, ctx: &mut Rltk) -> ItemMenuResult {
         "ESCAPE to cancel",
     );
 
+    let mut equippable: Vec<Entity> = Vec::new();
     let mut j = 0;
-    for (_pack, name) in (&backpack, &names)
+    for (entity, _pack, name) in (&entities, &backpack, &names)
         .join()
-        .filter(|item| item.0.owner == *player_entity)
+        .filter(|item| item.1.owner == *player_entity)
     {
         ctx.set(
             17,
@@ -223,15 +225,25 @@ pub fn show_inventory(gs: &mut State, ctx: &mut Rltk) -> ItemMenuResult {
         );
 
         ctx.print(21, y, &name.name.to_string());
+        equippable.push(entity);
         y += 1;
         j += 1;
     }
 
     match ctx.key {
-        None => ItemMenuResult::NoResponse,
+        None => (ItemMenuResult::NoResponse, None),
         Some(key) => match key {
-            VirtualKeyCode::Escape => ItemMenuResult::Cancel,
-            _ => ItemMenuResult::NoResponse,
+            VirtualKeyCode::Escape => (ItemMenuResult::Cancel, None),
+            _ => {
+                let selection = rltk::letter_to_option(key);
+                if selection > -1 && selection < count as i32 {
+                    return (
+                        ItemMenuResult::Selected,
+                        Some(equippable[selection as usize]),
+                    );
+                }
+                (ItemMenuResult::NoResponse, None)
+            }
         },
     }
 }

src/inventory_system.rs

@@ -1,4 +1,7 @@
-use crate::{gamelog::GameLog, InBackpack, Name, Position, WantsToPickupItem};
+use crate::{
+    gamelog::GameLog, CombatStats, InBackpack, Name, Position, Potion, WantsToDrinkPotion,
+    WantsToPickupItem,
+};
 use specs::prelude::*;
 
 pub struct ItemCollectionSystem {}
@@ -40,3 +43,51 @@ impl<'a> System<'a> for ItemCollectionSystem {
         wants_pickup.clear();
     }
 }
+
+pub struct PotionUseSystem {}
+
+impl<'a> System<'a> for PotionUseSystem {
+    #[allow(clippy::type_complexity)]
+    type SystemData = (
+        ReadExpect<'a, Entity>,
+        WriteExpect<'a, GameLog>,
+        Entities<'a>,
+        WriteStorage<'a, WantsToDrinkPotion>,
+        ReadStorage<'a, Name>,
+        ReadStorage<'a, Potion>,
+        WriteStorage<'a, CombatStats>,
+    );
+
+    fn run(&mut self, data: Self::SystemData) {
+        let (
+            player_entity,
+            mut gamelog,
+            entities,
+            mut wants_drink,
+            names,
+            potions,
+            mut combat_stats,
+        ) = data;
+
+        for (entity, drink, stats) in (&entities, &wants_drink, &mut combat_stats).join() {
+            match potions.get(drink.potion) {
+                None => {}
+                Some(potion) => {
+                    stats.hp = i32::min(stats.max_hp, stats.hp + potion.heal_amount);
+                    if entity == *player_entity {
+                        gamelog.entries.push(format!(
+                            "You drink the {}, healing {} hp.",
+                            names.get(drink.potion).unwrap().name,
+                            potion.heal_amount
+                        ));
+                    }
+                    entities
+                        .delete(drink.potion)
+                        .expect("Failed to delete potion");
+                }
+            }
+        }
+
+        wants_drink.clear();
+    }
+}

src/main.rs

@@ -24,7 +24,7 @@ mod gui;
 pub use gamelog::GameLog;
 mod inventory_system;
 mod spawner;
-use inventory_system::ItemCollectionSystem;
+use inventory_system::{ItemCollectionSystem, PotionUseSystem};
 
 pub const MAP_SIZE: usize = 80 * 50;
 
@@ -61,6 +61,9 @@ impl State {
         let mut pickup = ItemCollectionSystem {};
         pickup.run_now(&self.ecs);
 
+        let mut potions = PotionUseSystem {};
+        potions.run_now(&self.ecs);
+
         self.ecs.maintain();
     }
 }
@@ -77,6 +80,7 @@ impl GameState for State {
         match newrunstate {
             RunState::PreRun => {
                 self.run_systems();
+                self.ecs.maintain();
                 newrunstate = RunState::AwaitingInput;
             }
             RunState::AwaitingInput => {
@@ -84,15 +88,33 @@ impl GameState for State {
             }
             RunState::PlayerTurn => {
                 self.run_systems();
+                self.ecs.maintain();
                 newrunstate = RunState::MonsterTurn;
             }
             RunState::MonsterTurn => {
                 self.run_systems();
+                self.ecs.maintain();
                 newrunstate = RunState::AwaitingInput;
             }
             RunState::ShowInventory => {
-                if gui::show_inventory(self, ctx) == gui::ItemMenuResult::Cancel {
-                    newrunstate = RunState::AwaitingInput;
+                let result = gui::show_inventory(self, ctx);
+                match result.0 {
+                    gui::ItemMenuResult::Cancel => newrunstate = RunState::AwaitingInput,
+                    gui::ItemMenuResult::NoResponse => {}
+                    gui::ItemMenuResult::Selected => {
+                        let item_entity = result.1.unwrap();
+                        let mut intent = self.ecs.write_storage::<WantsToDrinkPotion>();
+                        intent
+                            .insert(
+                                *self.ecs.fetch::<Entity>(),
+                                WantsToDrinkPotion {
+                                    potion: item_entity,
+                                },
+                            )
+                            .expect("failed to add intent to drink potion");
+
+                        newrunstate = RunState::PlayerTurn;
+                    }
                 }
             }
         }
@@ -145,6 +167,7 @@ fn main() -> rltk::BError {
     gs.ecs.register::<Potion>();
     gs.ecs.register::<InBackpack>();
     gs.ecs.register::<WantsToPickupItem>();
+    gs.ecs.register::<WantsToDrinkPotion>();
 
     let map: Map = Map::new_map_rooms_and_corridors();
     let (player_x, player_y) = map.rooms[0].center();