From 0ee91f6d77571260580c6e37153a847fac8fb72f Mon Sep 17 00:00:00 2001
From: Oxore <oxore@protonmail.com>
Date: Sun, 30 Jul 2023 19:41:13 +0300
Subject: Impl event loop using nonblock read and sleep

---
 Cargo.lock  | 10 ++++++++++
 Cargo.toml  |  1 +
 src/main.rs | 44 ++++++++++++++++++++++++++++++++------------
 3 files changed, 43 insertions(+), 12 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 0eafa82..0d52afd 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -25,6 +25,15 @@ version = "0.2.147"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b4668fb0ea861c1df094127ac5f1da3409a82116a4ba74fca2e58ef927159bb3"
 
+[[package]]
+name = "nonblock"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "51c7a4f22e5f2e2bd805d6ab56f1ae87eb1815673e1b452048896fb687a8a3d4"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "ppv-lite86"
 version = "0.2.17"
@@ -35,6 +44,7 @@ checksum = "5b40af805b3121feab8a3c29f04d8ad262fa8e0561883e7653e024ae4479e6de"
 name = "puzzle"
 version = "0.1.0"
 dependencies = [
+ "nonblock",
  "rand",
  "termios",
 ]
diff --git a/Cargo.toml b/Cargo.toml
index 3be4420..624495f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -8,3 +8,4 @@ edition = "2021"
 [dependencies]
 rand = "0.8.5"
 termios = "0.3.3"
+nonblock = "0.2.0"
diff --git a/src/main.rs b/src/main.rs
index 245c2b1..fc8c0a5 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,7 +1,8 @@
 extern crate termios;
 
 use rand::Rng;
-use std::io::Read;
+use std::time::Duration;
+use nonblock::NonBlockingReader;
 
 const FIELD_COLS: usize = 10;
 const FIELD_ROWS_VISIBLE: usize = 20;
@@ -18,6 +19,12 @@ const CELLS_S: [i8; FIGURE_SIZE] = [0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0,
 const CELLS_T: [i8; FIGURE_SIZE] = [0, 0, 0, 0, 1, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0];
 const CELLS_Z: [i8; FIGURE_SIZE] = [0, 0, 0, 0, 0, 1, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0];
 
+enum StepResult {
+    StateChanged,
+    Quit,
+    Noop,
+}
+
 #[derive(Clone)]
 #[derive(Debug)]
 enum FigureKind {
@@ -165,11 +172,13 @@ impl Game {
         self.x = 0;
         self.y = 0;
     }
-    fn step(&mut self, fd: &mut std::io::Stdin) -> Option<()> {
-        let mut r: [u8;1]=[0];
-        fd.read(&mut r[..]).unwrap();
-        match r[0] as char {
-            'q' => return None,
+    fn step(&mut self, c_optional: Option<char>) -> StepResult {
+        if let None = c_optional {
+            return StepResult::Noop;
+        }
+        let c = c_optional.unwrap();
+        match c {
+            'q' => return StepResult::Quit,
             ' ' => {
                 if !self.field.has_collision(&self.figure, self.x, self.y) {
                     self.place()
@@ -212,7 +221,7 @@ impl Game {
             }
             _ => {},
         }
-        Some(())
+        StepResult::StateChanged
     }
 }
 
@@ -266,12 +275,23 @@ fn main() {
     clear_screen();
     let mut game = Game::default();
     display_game(&game);
-    let mut stdin = std::io::stdin();
-    loop {
-        if let None = game.step(&mut stdin) {
-            break;
+    let mut noblock_stdin = NonBlockingReader::from_fd(std::io::stdin()).unwrap();
+    'outer: while !noblock_stdin.is_eof() {
+        let mut buf = String::new();
+        noblock_stdin.read_available_to_string(&mut buf).unwrap();
+        let mut changed = false;
+        for c in buf.bytes() {
+            let result = game.step(Some(c as char));
+            match result {
+                StepResult::StateChanged => changed = true,
+                StepResult::Noop => {},
+                StepResult::Quit => break 'outer,
+            }
+        }
+        if changed {
+            display_game(&game);
         }
-        display_game(&game);
+        std::thread::sleep(Duration::from_millis(1));
     }
     termios::tcsetattr(0, termios::TCSADRAIN, &termios_state_initial).unwrap();
 }
-- 
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