Retry the start of the download if failing

src/main.rs

@@ -14,7 +14,7 @@ use std::collections::HashMap;
 use std::time::{Instant, Duration};
 
 use json::JsonValue;
-use reqwest::{Client, RedirectPolicy};
+use reqwest::{Client, Response, RedirectPolicy};
 use reqwest::header::{Cookie, Charset, SetCookie};
 use reqwest::header::{ContentDisposition, DispositionType, DispositionParam};
 use zip::ZipArchive;
@@ -34,6 +34,8 @@ mod catalogs {
 
 // TODO: use clap for proper CLI
 // TODO: clippy
+// TODO: replace unwraps with descriptive expects
+// TODO: retry some things if sensible
 
 lazy_static! {
     static ref CLIENT: Client = {
@@ -126,8 +128,11 @@ fn download_catalog(catalog_name: &str, out_dir: &Path, auth: &str) {
              presentations.len());
 
     for (i, presentation) in presentations.iter().enumerate() {
-        println!("Downloading {}/{}: {}", i + 1, presentations.len(), presentation.name);
-        download_presentation(&presentation, out_dir, auth);
+        println!("Downloading {}/{}: {}",
+                 i + 1,
+                 presentations.len(),
+                 presentation.name);
+        download_presentation(presentation, out_dir, auth);
     }
 }
 
@@ -151,26 +156,46 @@ fn get_catalog_id(name: &str, auth: &str) -> String {
 }
 
 fn download_presentation(presentation: &Presentation, out_dir: &Path, auth: &str) {
-    let response = CLIENT.get(&presentation.download_url)
-        .header(construct_cookie(auth))
-        .send()
-        .unwrap();
+    fn try_download(presentation: &Presentation, auth: &str) -> Option<(Response, String)> {
+        let response = CLIENT.get(&presentation.download_url)
+            .header(construct_cookie(auth))
+            .send()
+            .unwrap();
 
-    let filename = {
-        let content_disposition: &ContentDisposition = response.headers().get().unwrap();
-        assert_eq!(content_disposition.disposition, DispositionType::Attachment);
-        let mut name = None;
-        for param in &content_disposition.parameters {
-            match *param {
-                DispositionParam::Filename(ref charset, _, ref vec) => {
-                    assert_eq!(&Charset::Ext("UTF-8".to_string()), charset);
-                    name = Some(String::from_utf8(vec.to_vec()).unwrap());
+        let filename = if let Some(content_disposition) =
+            response.headers().get::<ContentDisposition>() {
+            assert_eq!(content_disposition.disposition, DispositionType::Attachment);
+            let mut name = None;
+            for param in &content_disposition.parameters {
+                match *param {
+                    DispositionParam::Filename(ref charset, _, ref vec) => {
+                        assert_eq!(&Charset::Ext("UTF-8".to_string()), charset);
+                        name = Some(String::from_utf8(vec.to_vec()).unwrap());
+                    }
+                    _ => continue,
                 }
-                _ => continue,
             }
+            name.expect("Missing filename in ContentDisposition!")
+        } else {
+            return None;
+        };
+
+        Some((response, filename))
+    }
+
+    let mut tries = 0;
+    let mut tuple = None;
+    while tries < 8 {
+        let try = try_download(presentation, auth);
+        if try.is_some() {
+            tuple = try;
         }
-        name.expect("Missing filename in ContentDisposition!")
-    };
+        tries += 1;
+    }
+    if tuple.is_none() {
+        panic!("Failed to get a proper response while trying to download presentation!");
+    }
+    let (response, filename) = tuple.unwrap();
 
     let mut path = PathBuf::from(out_dir);
     path.push(fix_filename(&filename));