From 7f7339ab6d3d8a5aba7f8ba44997589ffd50fc94 Mon Sep 17 00:00:00 2001
From: Rabindra Dhakal <contact@qaidvoid.dev>
Date: Fri, 11 Oct 2024 19:52:20 +0545
Subject: [PATCH] feat(download): introduce ability to download arbitrary files

---
 src/cli.rs           |  9 ++++++
 src/lib.rs           |  5 +++
 src/misc/download.rs | 76 ++++++++++++++++++++++++++++++++++++++++++++
 src/misc/mod.rs      |  1 +
 4 files changed, 91 insertions(+)
 create mode 100644 src/misc/download.rs
 create mode 100644 src/misc/mod.rs

diff --git a/src/cli.rs b/src/cli.rs
index 396984b..26a53e2 100644
--- a/src/cli.rs
+++ b/src/cli.rs
@@ -109,4 +109,13 @@ pub enum Commands {
         #[arg(required = true)]
         package: String,
     },
+
+    /// Download arbitrary files
+    #[command(arg_required_else_help = true)]
+    #[clap(name = "download", visible_alias = "dl")]
+    Download {
+        /// Links to files
+        #[arg(required = true)]
+        links: Vec<String>,
+    },
 }
diff --git a/src/lib.rs b/src/lib.rs
index ea1909c..ce1760d 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,6 +1,7 @@
 use anyhow::Result;
 use clap::Parser;
 use cli::{Args, Commands};
+use misc::download::download_and_save;
 use registry::PackageRegistry;
 
 use core::{
@@ -10,6 +11,7 @@ use core::{
 
 mod cli;
 mod core;
+mod misc;
 mod registry;
 
 pub async fn init() -> Result<()> {
@@ -54,6 +56,9 @@ pub async fn init() -> Result<()> {
         Commands::Use { package } => {
             registry.use_package(&package).await?;
         }
+        Commands::Download { links } => {
+            download_and_save(links.as_ref()).await?;
+        }
     };
 
     Ok(())
diff --git a/src/misc/download.rs b/src/misc/download.rs
new file mode 100644
index 0000000..7824850
--- /dev/null
+++ b/src/misc/download.rs
@@ -0,0 +1,76 @@
+use std::{fs::Permissions, os::unix::fs::PermissionsExt, path::Path};
+
+use anyhow::{Context, Result};
+use chrono::Utc;
+use futures::StreamExt;
+use reqwest::Url;
+use tokio::fs;
+
+use crate::core::util::format_bytes;
+
+fn extract_filename(url: &str) -> String {
+    Path::new(url)
+        .file_name()
+        .map(|name| name.to_string_lossy().to_string())
+        .unwrap_or_else(|| {
+            let dt = Utc::now().timestamp();
+            dt.to_string()
+        })
+}
+
+fn is_elf(content: &[u8]) -> bool {
+    let magic_bytes = &content[..4.min(content.len())];
+    let elf_bytes = [0x7f, 0x45, 0x4c, 0x46];
+    magic_bytes == elf_bytes
+}
+
+async fn download(url: &str) -> Result<()> {
+    let client = reqwest::Client::new();
+    let response = client.get(url).send().await?;
+
+    if !response.status().is_success() {
+        return Err(anyhow::anyhow!(
+            "Error fetching {} [{}]",
+            url,
+            response.status()
+        ));
+    }
+
+    let filename = extract_filename(url);
+    let mut content = Vec::new();
+
+    println!(
+        "Downloading file from {} [{}]",
+        url,
+        format_bytes(response.content_length().unwrap_or_default())
+    );
+
+    let mut stream = response.bytes_stream();
+
+    while let Some(chunk) = stream.next().await {
+        let chunk = chunk.context("Failed to read chunk")?;
+        content.extend_from_slice(&chunk);
+    }
+
+    fs::write(&filename, &content).await?;
+
+    if is_elf(&content) {
+        fs::set_permissions(&filename, Permissions::from_mode(0o755)).await?;
+    }
+
+    println!("Downloaded {}", filename);
+
+    Ok(())
+}
+
+pub async fn download_and_save(links: &[String]) -> Result<()> {
+    for link in links {
+        if let Ok(url) = Url::parse(link) {
+            download(url.as_str()).await?;
+        } else {
+            eprintln!("{} is not a valid URL", link);
+        };
+    }
+
+    Ok(())
+}
diff --git a/src/misc/mod.rs b/src/misc/mod.rs
new file mode 100644
index 0000000..674b799
--- /dev/null
+++ b/src/misc/mod.rs
@@ -0,0 +1 @@
+pub mod download;