stream files to disk

- Greatly reduced memory usage while downloading
- Added progressbar, download rate
- Added async runtime
- Tweaks to allow usage of async download function

src/http_async.rs

@@ -0,0 +1,52 @@
+use std::cmp::min;
+use std::fs::File;
+use std::io::Write;
+use std::path::PathBuf;
+
+use colored::*;
+use futures_util::StreamExt;
+use indicatif::ProgressBar;
+use reqwest::Client;
+
+use crate::misc;
+
+pub async fn download_file(
+    client: &Client,
+    pb: &ProgressBar,
+    url: &str,
+    path: &PathBuf,
+    size: u64,
+) -> Result<(), String> {
+    let res = client
+        .get(url)
+        .send()
+        .await
+        .or(Err(format!("Failed to GET from '{}'", &url)))?;
+    // Fix for CF shenanigans
+    let total_size = res.content_length().unwrap_or(size);
+    pb.set_length(total_size);
+    pb.println(format!(
+        "[{}] {} ({})",
+        "Downloading".bright_yellow(),
+        misc::cute_path(path),
+        misc::human_readable_bytes(total_size)
+    ));
+    pb.set_message(misc::cute_path(path));
+
+    let mut file =
+        File::create(path).or(Err(format!("Failed to create file '{}'", path.display())))?;
+    let mut downloaded: u64 = 0;
+    let mut stream = res.bytes_stream();
+
+    while let Some(item) = stream.next().await {
+        let chunk = item.or(Err("Error while downloading file"))?;
+        file.write_all(&chunk)
+            .or(Err("Error while writing to file"))?;
+        let new = min(downloaded + (chunk.len() as u64), total_size);
+        downloaded = new;
+        pb.set_position(new);
+    }
+
+    pb.set_message("");
+    Ok(())
+}