1 files changed, 116 insertions, 0 deletions
diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 0000000..606326e
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,116 @@
+use rand::{thread_rng, Rng};
+use std::{
+    io::{stdout, Read, Write},
+    thread::sleep,
+    time::Duration,
+};
+use termion::{async_stdin, raw::IntoRawMode, terminal_size};
+
+const N_FISH: usize = 64;
+
+struct Turbofish {
+    x: i16,
+    y: u16,
+    speed: i16,
+    bold: bool,
+}
+
+impl Turbofish {
+    fn text(&self, offset: i16) -> String {
+        let s = if self.speed < 0 { "<>::" } else { "::<>" };
+        let s = if offset <= -4 {
+            ""
+        } else if offset < 0 {
+            &s[(-offset as usize)..]
+        } else if offset >= 4 {
+            ""
+        } else if offset > 0 {
+            &s[0..(4 - offset as usize)]
+        } else {
+            s
+        };
+        s.to_string()
+    }
+
+    fn tick(&mut self) {
+        self.x += self.speed;
+        self.bold = !self.bold;
+    }
+}
+
+fn clear(mut stdout: impl Write) {
+    write!(stdout, "{}", termion::clear::All).unwrap();
+}
+
+fn update(school_of_fish: &mut [Turbofish], columns: u16) {
+    for fish in school_of_fish.iter_mut() {
+        fish.tick();
+        if fish.x < -10 || fish.x > columns as i16 + 10 {
+            fish.speed *= -1;
+        }
+    }
+}
+
+fn render(mut stdout: impl Write, school_of_fish: &Vec<Turbofish>, columns: u16) {
+    for fish in school_of_fish {
+        let x = fish.x;
+        let y = fish.y;
+        if fish.bold {
+            write!(stdout, "{}", termion::style::Bold).unwrap();
+        }
+        write!(
+            stdout,
+            "{}{}{}",
+            termion::cursor::Goto(x.clamp(0, columns as i16 - 1) as u16 + 1, y + 1),
+            fish.text(if x < 0 {
+                x
+            } else if (x as u16) + 4 >= columns {
+                x + 4 - columns as i16
+            } else {
+                0
+            }),
+            termion::style::Reset,
+        )
+        .unwrap();
+    }
+}
+
+fn main() {
+    let mut stdin = async_stdin().bytes();
+    let mut stdout = stdout().into_raw_mode().unwrap();
+    let mut rng = thread_rng();
+
+    let (columns, lines) = terminal_size().unwrap();
+
+    let mut school_of_fish = Vec::with_capacity(N_FISH);
+    for _i in 0..N_FISH {
+        let x = rng.gen_range(0..(columns as i16 - 1));
+        let y = rng.gen_range(0..(lines - 1));
+        let speed = [-2, -1, 1, 2][rng.gen_range(0..4)];
+        school_of_fish.push(Turbofish {
+            x,
+            y,
+            speed,
+            bold: rng.gen(),
+        });
+    }
+
+    clear(&mut stdout);
+    stdout.flush().unwrap();
+
+    loop {
+        if let Some(Ok(b'q')) = stdin.next() {
+            break;
+        }
+
+        clear(&mut stdout);
+        update(&mut school_of_fish, columns);
+        render(&mut stdout, &school_of_fish, columns);
+        stdout.flush().unwrap();
+
+        sleep(Duration::from_millis(100));
+    }
+
+    clear(&mut stdout);
+    stdout.flush().unwrap();
+}