Use clap to provide a CLI

src/main.rs

@@ -1,3 +1,4 @@
+extern crate clap;
 extern crate cookie;
 extern crate dotenv;
 extern crate json;
@@ -7,12 +8,13 @@ extern crate reqwest;
 extern crate zip;
 
 use std::env;
-use std::fs::File;
-use std::io::{Read, BufReader, Write};
-use std::path::{Path, PathBuf};
 use std::collections::HashMap;
+use std::fs::File;
+use std::io::{self, Read, BufReader, Write};
+use std::path::{Path, PathBuf};
 use std::time::{Instant, Duration};
 
+use clap::{App, Arg};
 use json::JsonValue;
 use reqwest::{Client, Response, RedirectPolicy, RequestBuilder};
 use reqwest::header::{Cookie, Charset, SetCookie};
@@ -67,39 +69,68 @@ impl<'a> From<&'a JsonValue> for Presentation {
 }
 
 fn main() {
-    let catalog_def = DS;
+    let matches = App::new("TumMediasiteDownloader")
+        .author("Boris-Chengbiao Zhou <bobo1239@web.de>")
+        .about("Downloads \'catalogs\' from the TUM's Mediasite lecture archive.")
+        .arg(Arg::with_name("CATALOG_NAME")
+            .help("name of the catalog e.g. from the URL:\n\
+                   https://streams.tum.de/Mediasite/Catalog/catalogs/era-2016 -> era-2016\n\
+                   special cases (WS16/17; login included): DS, EIDI, ERA")
+            .required(true)
+            .index(1))
+        .arg(Arg::with_name("OUTPUT_DIRECTORY")
+            .help("where to output the downloaded files")
+            .required(true)
+            .index(2))
+        .arg(Arg::with_name("username")
+            .short("u")
+            .help("username for login; can be omitted if the user from .env should be used")
+            .requires("password")
+            .takes_value(true))
+        .arg(Arg::with_name("password")
+            .short("p")
+            .help("password for login; can be omitted if the user from .env should be used")
+            .requires("username")
+            .takes_value(true))
+        .get_matches();
 
-    let out_dir = get_output_directory();
+    let catalog_def = match matches.value_of("CATALOG_NAME").unwrap() {
+        "DS" => DS,
+        "EIDI" => EIDI,
+        "ERA" => ERA,
+        n => {
+            if let Some(username) = matches.value_of("username") {
+                let password = matches.value_of("password").unwrap();
+                (n, Some((username, password)))
+            } else {
+                (n, None)
+            }
+        }
+    };
+
+    let out_dir = Path::new(matches.value_of("OUTPUT_DIRECTORY").unwrap());
+    if out_dir.exists() {
+        assert!(out_dir.is_dir());
+    } else {
+        ::std::fs::create_dir_all(out_dir).expect("Failed to create output directory!");
+    }
 
-    let default_login = get_default_login();
     let (catalog_name, (username, password)) = if let Some((user, pass)) = catalog_def.1 {
         (catalog_def.0, (user.to_string(), pass.to_string()))
     } else {
-        (catalog_def.0, default_login)
+        (catalog_def.0, get_default_login())
     };
 
     println!("Preparing to download catalog \"{}\"!", catalog_name);
 
     let auth = get_auth(&username, &password);
-    // let out_dir = Path::new("/run/media/bobo1239/30E0E835E0E7FECA/downloaded");
-    // let out_dir = Path::new("out");
-    download_catalog(catalog_name, &out_dir, &auth);
-}
-
-fn get_output_directory() -> PathBuf {
-    // The first argument is (usually) the executable
-    let path_str = env::args_os().nth(1).expect("No output directory specified!");
-    let path = Path::new(&path_str);
-    if path.exists() {
-        assert!(path.is_dir());
-    } else {
-        ::std::fs::create_dir_all(path).expect("Failed to create output directory!");
-    }
-    path.to_owned()
+    download_catalog(catalog_name, out_dir, &auth);
 }
 
 fn get_default_login() -> (String, String) {
-    dotenv::dotenv().expect("Missing .env!");
+    if dotenv::dotenv().is_err() {
+        println!("No .env found!");
+    }
 
     let username = env::var("TUM_USERNAME").expect("Missing TUM_USERNAME environment variable!");
     let password = env::var("TUM_PASSWORD").expect("Missing TUM_PASSWORD environment variable!");
@@ -118,6 +149,13 @@ fn get_auth(username: &str, password: &str) -> String {
                                                 .form(&form_data)
                                         },
                                         |res| res.headers().get::<SetCookie>().is_some());
+    // FIXME: We're somehow only getting "Object moved" instead of the actual response
+    //        => We can't determine if the login was successful
+    //        (we still get a MediasiteAuth cookie that is useless)
+    // let body = read_response_body(&mut res);
+    // if body.contains("Unknown username or bad password.") {
+    //     panic!("Unknown username or bad password!");
+    // }
 
     let set_cookie: &SetCookie = res.headers().get().unwrap();
     let cookie = cookie::Cookie::parse(set_cookie.0[0].to_string())
@@ -151,7 +189,9 @@ fn get_catalog_id(name: &str, auth: &str) -> String {
     let body = read_response_body(&mut res);
 
     let prefix = "CatalogId: '";
-    let idx = body.find(prefix).expect("Failed to find CatalogId on the catalog page!");
+    let idx = body.find(prefix)
+        .expect("Failed to find CatalogId on the catalog page! Perhaps you got the wrong catalog \
+                 name or an invalid login?");
     let pre_len = prefix.len();
     // Assuming all catalog ids follow this pattern!
     let len = "a6fca0c1-0be4-4e66-83b7-bcdc4eb5e95e".len();
@@ -211,7 +251,7 @@ fn download_presentation(presentation: &Presentation, out_dir: &Path, auth: &str
         let len = match reader.read(&mut buf) {
             Ok(0) => break,
             Ok(len) => len,
-            Err(ref e) if e.kind() == ::std::io::ErrorKind::Interrupted => continue,
+            Err(ref e) if e.kind() == io::ErrorKind::Interrupted => continue,
             Err(e) => panic!(e),
         };