From 59a791de56d0d9d3a0f9a0b9365a2f7ece49b166 Mon Sep 17 00:00:00 2001
From: Timothy Warren <twarren@nabancard.com>
Date: Thu, 21 Oct 2021 14:24:40 -0400
Subject: [PATCH] Finish chapter 2.1

---
 Cargo.toml  |  1 +
 src/main.rs | 81 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 81 insertions(+), 1 deletion(-)

diff --git a/Cargo.toml b/Cargo.toml
index 64ace80..5cb0d18 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,7 @@
 [package]
 name = "roguelike_tutorial"
 version = "0.1.0"
+rust-version = "1.56"
 edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
diff --git a/src/main.rs b/src/main.rs
index dc20cc0..0b49d56 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -16,14 +16,77 @@ struct Renderable {
     bg: RGB,
 }
 
+#[derive(Component)]
+struct LeftMover {}
+
+#[derive(Component, Debug)]
+struct Player {}
+
 struct State {
     ecs: World,
 }
 
+fn try_move_player(delta_x: i32, delta_y: i32, ecs: &mut World) {
+    let mut positions = ecs.write_storage::<Position>();
+    let mut players = ecs.write_storage::<Player>();
+
+    for (_player, pos) in (&mut players, &mut positions).join() {
+        pos.x = min(79, max(0, pos.x + delta_x));
+        pos.y = min(49, max(0, pos.y + delta_y));
+    }
+}
+
+fn player_input(gs: &mut State, ctx: &mut Rltk) {
+    // Player movement
+    match ctx.key {
+        None => {} // Nothing happened
+        Some(key) => match key {
+            VirtualKeyCode::Left => try_move_player(-1, 0, &mut gs.ecs),
+            VirtualKeyCode::Right => try_move_player(1, 0, &mut gs.ecs),
+            VirtualKeyCode::Up => try_move_player(0, -1, &mut gs.ecs),
+            VirtualKeyCode::Down => try_move_player(0, 1, &mut gs.ecs),
+            _ => {},
+        },
+    }
+}
+
 impl GameState for State {
     fn tick(&mut self, ctx: &mut Rltk) {
         ctx.cls();
-        ctx.print(1, 1, "Hello Rust World");
+
+        player_input(self, ctx);
+        self.run_systems();
+
+        let positions = self.ecs.read_storage::<Position>();
+        let renderables = self.ecs.read_storage::<Renderable>();
+
+        for (pos, render) in (&positions, &renderables).join() {
+            ctx.set(pos.x, pos.y, render.fg, render.bg, render.glyph);
+        }
+    }
+}
+
+struct LeftWalker {}
+
+impl<'a> System<'a> for LeftWalker {
+    type SystemData = (ReadStorage<'a, LeftMover>, WriteStorage<'a, Position>);
+
+    fn run(&mut self, (lefty, mut pos): Self::SystemData) {
+        for (_lefty, pos) in (&lefty, &mut pos).join() {
+            pos.x -= 1;
+
+            if pos.x < 0 {
+                pos.x = 79;
+            }
+        }
+    }
+}
+
+impl State {
+    fn run_systems(&mut self) {
+        let mut lw = LeftWalker{};
+        lw.run_now(&self.ecs);
+        self.ecs.maintain();
     }
 }
 
@@ -38,6 +101,8 @@ fn main() -> rltk::BError {
 
     gs.ecs.register::<Position>();
     gs.ecs.register::<Renderable>();
+    gs.ecs.register::<LeftMover>();
+    gs.ecs.register::<Player>();
 
     gs.ecs
         .create_entity()
@@ -47,7 +112,21 @@ fn main() -> rltk::BError {
             fg: RGB::named(rltk::YELLOW),
             bg: RGB::named(rltk::BLACK),
         })
+        .with(Player {})
         .build();
 
+    for i in 0..10 {
+        gs.ecs
+            .create_entity()
+            .with(Position { x: i * 7, y: 20 })
+            .with(Renderable {
+                glyph: rltk::to_cp437('☺'),
+                fg: RGB::named(rltk::RED),
+                bg: RGB::named(rltk::BLACK),
+            })
+            .with(LeftMover {})
+            .build();
+    }
+
     rltk::main_loop(context, gs)
 }