Add -f flag for adding links from a file instead of needing to use cat

README.md

@@ -12,7 +12,13 @@ Paperoni is a web article downloader written in Rust. The downloaded articles ar
 paperoni https://en.wikipedia.org/wiki/Pepperoni
 ```
 
-Paperoni also supports passing multiple links as arguments. If you are on a Unix-like OS, you can simply do something like this:
+Paperoni also supports passing multiple links as arguments. These can be read from a file using the `-f` flag.
+
+```sh
+paperoni -f links.txt
+```
+
+Alternatively, if you are on a Unix-like OS, you can simply do something like this:
 
 ```sh
 cat links.txt | xargs paperoni

src/cli.rs

@@ -18,4 +18,11 @@ It takes a url and downloads the article content from it and saves it to an epub
                 .help("Urls of web articles")
                 .multiple(true),
         )
+        .arg(
+            Arg::with_name("file")
+                .short("f")
+                .long("file")
+                .help("Input file containing links")
+                .takes_value(true),
+        )
 }

src/main.rs

@@ -1,7 +1,7 @@
 #[macro_use]
 extern crate lazy_static;
 
-use std::fs::File;
+use std::{fs::File, io::Read};
 
 use async_std::task;
 use epub_builder::{EpubBuilder, EpubContent, ZipLibrary};
@@ -15,8 +15,27 @@ use extractor::Extractor;
 fn main() {
     let app = cli::cli_init();
     let arg_matches = app.get_matches();
+    let mut urls: Vec<String> = match arg_matches.value_of("file") {
+        Some(file_name) => {
+            if let Ok(mut file) = File::open(file_name) {
+                let mut content = String::new();
+                match file.read_to_string(&mut content) {
+                    Ok(_) => content.lines().map(|line| line.to_owned()).collect(),
+                    Err(_) => vec![],
+                }
+            } else {
+                println!("Unable to open file: {}", file_name);
+                vec![]
+            }
+        }
+        None => vec![],
+    };
+
     if let Some(vals) = arg_matches.values_of("urls") {
-        let urls = vals.map(|val| val.to_string()).collect::<Vec<_>>();
+        urls.extend(vals.map(|val| val.to_string()));
+    }
+
+    if !urls.is_empty() {
         download(urls);
     }
 }