From f898a97005844d5c451842eca63871ba382f5d96 Mon Sep 17 00:00:00 2001
From: Rose Hogenson <rosehogenson@posteo.net>
Date: Fri, 29 Dec 2023 11:20:05 -0800
Subject: Allow moving the cursor with the arrow keys.

---
 src/term.rs | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

(limited to 'src/term.rs')

diff --git a/src/term.rs b/src/term.rs
index 149f00f..20098a0 100644
--- a/src/term.rs
+++ b/src/term.rs
@@ -1,4 +1,5 @@
 use libc::{termios, winsize};
+use std::io::{Read, Stdin};
 
 pub fn size() -> Option<winsize> {
     unsafe {
@@ -59,3 +60,57 @@ pub fn raw() -> Option<RawHandle> {
     }
     return Some(RawHandle { old: old });
 }
+
+pub enum Key {
+    CtrlQ,
+    Up,
+    Down,
+    Left,
+    Right,
+    Char(char),
+}
+
+pub fn read_key(stdin: &mut Stdin) -> Result<Key, String> {
+    const CTRL_Q: u8 = 17;
+    const ESC: u8 = 27;
+
+    loop {
+        let mut buf = vec![0; 1];
+        if let Err(err) = stdin.read_exact(&mut buf) {
+            return Err(format!("read input: {}", err));
+        }
+        if buf[0] == CTRL_Q {
+            return Ok(Key::CtrlQ);
+        }
+        if buf[0] != ESC {
+            return Ok(Key::Char(char::from(buf[0])));
+        }
+        // Try to handle an escape sequence.
+        let mut buf = vec![0; 2];
+        if let Err(err) = stdin.read_exact(&mut buf) {
+            return Err(format!("read input: {}", err));
+        }
+        if buf[0] != b'[' {
+            // Unknown escape sequence, just read another key.
+            continue;
+        }
+        match buf[1] {
+            b'A' => {
+                return Ok(Key::Up);
+            }
+            b'B' => {
+                return Ok(Key::Down);
+            }
+            b'C' => {
+                return Ok(Key::Right);
+            }
+            b'D' => {
+                return Ok(Key::Left);
+            }
+            _ => {
+                // Unknown key, just ignore it.
+                continue;
+            }
+        }
+    }
+}
-- 
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