feat(cli): add line by line file reversal

src/lib.rs

@@ -1,6 +1,6 @@
 use std::{
-    fs::{read_to_string, File},
+    fs::{read_to_string, write},
-    io::{self, Write},
+    io::{self},
     path::PathBuf,
 };
 
@@ -17,6 +17,9 @@ pub struct Cli {
     /// Output file path (optional)
     #[arg(short, long)]
     pub output: Option<PathBuf>,
+    /// Reverse by line instead of the whole content
+    #[arg(short, long)]
+    pub line_by_line: bool,
 }
 
 pub fn encode(s: &str) -> String {
@@ -27,27 +30,28 @@ pub fn encode_string(s: &str) -> String {
     encode(s)
 }
 
-pub fn encode_file(path: impl Into<PathBuf>) -> io::Result<String> {
+pub fn encode_file(path: impl Into<PathBuf>, line_by_line: bool) -> io::Result<String> {
     let path = path.into();
     let content = read_to_string(path)?;
+    if line_by_line {
+        return Ok(content
+            .lines()
+            .map(|line| encode(line))
+            .collect::<Vec<String>>()
+            .join("\n"));
+    }
     Ok(encode(&content))
 }
 
-pub fn write_output(content: &str, path: &PathBuf) -> io::Result<()> {
-    let mut file = File::create(path)?;
-    file.write_all(content.as_bytes())?;
-    Ok(())
-}
-
 pub fn process_input(cli: &Cli) -> io::Result<Option<String>> {
     let result = if cli.file {
-        encode_file(&cli.input)?
+        encode_file(&cli.input, cli.line_by_line)?
     } else {
         encode_string(&cli.input)
     };
 
     if let Some(output_path) = &cli.output {
-        write_output(&result, &output_path)?;
+        write(output_path, result)?;
         return Ok(None);
     }
     Ok(Some(result))