Suggestion.apply_to(): Use line endings consistent with file

Make the suggestion's line endings consistent with those used in the
file.

By default, the suggestion block we get from the GitHub API uses CRLF
line endings. These need to be converted to be consistent with the file
the change is being applied to.

1 files changed, 36 insertions, 2 deletions

diff --git a/src/lib.rs b/src/lib.rs
index a510b9f..3074dda 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -66,6 +66,12 @@ impl<'a> Client<'a> {
     }
 }
 
+#[derive(Debug, PartialEq)]
+enum LineEnding {
+    Lf,
+    CrLf,
+}
+
 #[derive(Debug, Deserialize)]
 pub struct Suggestion {
     #[serde(rename = "diff_hunk")]
@@ -111,9 +117,20 @@ impl Suggestion {
     }
 
     fn suggestion(&self) -> String {
+        self.suggestion_with_line_ending(&LineEnding::Lf)
+    }
+
+    fn suggestion_with_line_ending(&self, line_ending: &LineEnding) -> String {
         let re = Regex::new(r"(?s).*(?-s)```\s*suggestion.*\n").unwrap();
         let s = re.replace(&self.comment, "");
-        s.replace("```", "")
+        let s = s.replace("```", "");
+
+        // Suggestion blocks use CRLF by default.
+        if *line_ending == LineEnding::Lf {
+            return s.replace('\r', "");
+        }
+
+        s
     }
 
     pub fn apply(&self) -> Result<(), Error> {
@@ -143,14 +160,31 @@ impl Suggestion {
     ) -> Result<(), Error> {
         let original = File::open(from).unwrap();
         let reader = BufReader::new(original);
+        let mut line_ending = LineEnding::Lf;
 
         for (i, line) in reader.lines().enumerate() {
             let line_number = i + 1;
 
             match line {
                 Ok(l) => {
+                    // Determine which line endings the file uses by looking at
+                    // the first line. If the second-to-last character on the
+                    // first line is "\r", assume CRLF.  Otherwise, default to
+                    // LF.
+                    if line_number == 1 {
+                        if let Some(c) = l.chars().rev().nth(2) {
+                            if c == '\r' {
+                                line_ending = LineEnding::CrLf;
+                            }
+                        }
+                    }
+
                     if line_number == self.original_end_line {
-                        write!(writer, "{}", self.suggestion()).unwrap();
+                        write!(
+                            writer,
+                            "{}",
+                            self.suggestion_with_line_ending(&line_ending),
+                        ).unwrap();
                     } else if self.original_start_line.is_none()
                             || line_number < self.original_start_line.unwrap()
                             || line_number > self.original_end_line {