Import `less --no-init` avoidance from `bat`

3 files changed, 85 insertions, 1 deletions

diff --git a/src/bat/less.rs b/src/bat/less.rs
new file mode 100644
index 00000000..f7429333
--- /dev/null
+++ b/src/bat/less.rs
@@ -0,0 +1,62 @@
+use std::process::Command;
+
+pub fn retrieve_less_version() -> Option<usize> {
+    let cmd = Command::new("less").arg("--version").output().ok()?;
+    parse_less_version(&cmd.stdout)
+}
+
+fn parse_less_version(output: &[u8]) -> Option<usize> {
+    if output.starts_with(b"less ") {
+        let version = std::str::from_utf8(&output[5..]).ok()?;
+        let end = version.find(' ')?;
+        version[..end].parse::<usize>().ok()
+    } else {
+        None
+    }
+}
+
+#[test]
+fn test_parse_less_version_487() {
+    let output = b"less 487 (GNU regular expressions)
+Copyright (C) 1984-2016  Mark Nudelman
+
+less comes with NO WARRANTY, to the extent permitted by law.
+For information about the terms of redistribution,
+see the file named README in the less distribution.
+Homepage: http://www.greenwoodsoftware.com/less";
+
+    assert_eq!(Some(487), parse_less_version(output));
+}
+
+#[test]
+fn test_parse_less_version_529() {
+    let output = b"less 529 (Spencer V8 regular expressions)
+Copyright (C) 1984-2017  Mark Nudelman
+
+less comes with NO WARRANTY, to the extent permitted by law.
+For information about the terms of redistribution,
+see the file named README in the less distribution.
+Homepage: http://www.greenwoodsoftware.com/less";
+
+    assert_eq!(Some(529), parse_less_version(output));
+}
+
+#[test]
+fn test_parse_less_version_551() {
+    let output = b"less 551 (PCRE regular expressions)
+Copyright (C) 1984-2019  Mark Nudelman
+
+less comes with NO WARRANTY, to the extent permitted by law.
+For information about the terms of redistribution,
+see the file named README in the less distribution.
+Home page: http://www.greenwoodsoftware.com/less";
+
+    assert_eq!(Some(551), parse_less_version(output));
+}
+
+#[test]
+fn test_parse_less_version_wrong_program() {
+    let output = b"more from util-linux 2.34";
+
+    assert_eq!(None, parse_less_version(output));
+}
diff --git a/src/bat/mod.rs b/src/bat/mod.rs
index 04f6dbf7..362ba777 100644
--- a/src/bat/mod.rs
+++ b/src/bat/mod.rs
@@ -2,3 +2,4 @@ pub mod assets;
 pub mod dirs;
 pub mod output;
 pub mod terminal;
+mod less;
diff --git a/src/bat/output.rs b/src/bat/output.rs
index 193128f9..d23f5e80 100644
--- a/src/bat/output.rs
+++ b/src/bat/output.rs
@@ -9,6 +9,7 @@ use std::process::{Child, Command, Stdio};
 use shell_words;
 
 use crate::env;
+use super::less::retrieve_less_version;
 
 #[derive(Debug, Clone, Copy, PartialEq)]
 #[allow(dead_code)]
@@ -79,7 +80,27 @@ impl OutputType {
                 let mut process = if is_less {
                     let mut p = Command::new(&pager_path);
                     if args.is_empty() || replace_arguments_to_less {
-                        p.args(vec!["--RAW-CONTROL-CHARS", "--no-init"]);
+                        p.args(vec!["--RAW-CONTROL-CHARS"]);
+
+                        // Passing '--no-init' fixes a bug with '--quit-if-one-screen' in older
+                        // versions of 'less'. Unfortunately, it also breaks mouse-wheel support.
+                        //
+                        // See: http://www.greenwoodsoftware.com/less/news.530.html
+                        //
+                        // For newer versions (530 or 558 on Windows), we omit '--no-init' as it
+                        // is not needed anymore.
+                        match retrieve_less_version() {
+                            None => {
+                                p.arg("--no-init");
+                            }
+                            Some(version)
+                                if (version < 530 || (cfg!(windows) && version < 558)) =>
+                            {
+                                p.arg("--no-init");
+                            }
+                            _ => {}
+                        }
+
                         if quit_if_one_screen {
                             p.arg("--quit-if-one-screen");
                         }