[add] initial code

src/main.rs

@@ -0,0 +1,79 @@
+use std::io::BufRead;
+
+use clap::{command, Parser};
+use log::{debug, info, trace};
+use simple_logger::SimpleLogger;
+
+#[derive(Debug, Parser)]
+#[command(version, about)]
+struct ProgramArgs {
+    #[arg(short, long, default_value = "input.txt")]
+    input_file: String,
+    #[arg(short, long, default_value = "output.txt")]
+    output_file: String,
+}
+
+fn main() -> Result<(), std::io::Error> {
+    SimpleLogger::new()
+        .with_level(log::LevelFilter::Info)
+        .init()
+        .expect("Failed to init logging");
+
+    let ProgramArgs {
+        input_file,
+        output_file,
+    } = ProgramArgs::parse();
+
+    let mut reader = open_buf_reader(&input_file)?;
+
+    let mut hosts = Vec::with_capacity(10000);
+
+    let mut read_chars_len: usize;
+
+    loop {
+        let mut hostsfile_line: String = String::new();
+        read_chars_len = reader.read_line(&mut hostsfile_line)?;
+        if read_chars_len == 0 {
+            info!("Completed reading file {:?}", input_file);
+            break;
+        } else if read_chars_len == 1 && hostsfile_line.contains("\n") {
+            debug!("Empty str")
+        } else if hostsfile_line.starts_with("#") {
+            debug!("Comment line, ignore");
+        } else {
+            // println!("Line read - {:?}",stored_line);
+            get_host_from_line(&hostsfile_line).map(|host| {
+                hosts.push(host);
+            });
+        }
+        hostsfile_line.clear();
+    }
+
+    info!("Processed {} hosts", hosts.len());
+    debug!("Last item - {:?}", hosts.last());
+    write_hosts_to_file(hosts, output_file)?;
+    Ok(())
+}
+
+fn open_buf_reader(
+    input_file: &String,
+) -> Result<std::io::BufReader<std::fs::File>, std::io::Error> {
+    let file = std::fs::OpenOptions::new().read(true).open(input_file)?;
+    let reader = std::io::BufReader::new(file);
+    Ok(reader)
+}
+
+fn write_hosts_to_file(hosts: Vec<String>, file_name: String) -> Result<(), std::io::Error> {
+    std::fs::write(file_name, hosts.join("\n"))
+}
+
+fn get_host_from_line(stored_line: &String) -> Option<String> {
+    let arrays = stored_line.split(" ");
+    let elements: Vec<&str> = arrays.collect();
+    if elements.len() != 2 {
+        return None;
+    }
+    let host_string: String = elements[1].trim_end().into();
+    trace!("Read host {:?}", host_string);
+    Some(host_string)
+}