From cffb888ac846d6e2971214ef2d3e593476a440bc Mon Sep 17 00:00:00 2001
From: _ <_@_>
Date: Fri, 25 Mar 2022 00:44:43 +0000
Subject: [PATCH] :heavy_plus_sign: add download subcommand

---
 Cargo.lock                                    | 13 ++-
 crates/ptth_multi_call_server/Cargo.toml      |  3 +
 crates/ptth_multi_call_server/src/download.rs | 79 ++++++++++++++++++-
 3 files changed, 90 insertions(+), 5 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 99e697e..62dc089 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -584,6 +584,12 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "hex"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7f24254aa9a54b5c858eaee2f5bccdb46aaf0e486a595ed5fd8f86ba55232a70"
+
 [[package]]
 name = "http"
 version = "0.2.5"
@@ -1203,11 +1209,14 @@ version = "0.1.0"
 dependencies = [
  "anyhow",
  "ctrlc",
+ "futures-util",
+ "hex",
  "ptth_file_server",
  "ptth_server",
  "quic_demo",
  "reqwest",
  "rusty_ulid",
+ "sha2",
  "tokio",
  "tracing",
  "tracing-subscriber",
@@ -1776,9 +1785,9 @@ dependencies = [
 
 [[package]]
 name = "sha2"
-version = "0.9.8"
+version = "0.9.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b69f9a4c9740d74c5baa3fd2e547f9525fa8088a8a958e0ca2409a514e33f5fa"
+checksum = "4d58a1e1bf39749807d89cf2d98ac2dfa0ff1cb3faa38fbb64dd88ac8013d800"
 dependencies = [
  "block-buffer 0.9.0",
  "cfg-if",
diff --git a/crates/ptth_multi_call_server/Cargo.toml b/crates/ptth_multi_call_server/Cargo.toml
index 72affb4..b854b1e 100644
--- a/crates/ptth_multi_call_server/Cargo.toml
+++ b/crates/ptth_multi_call_server/Cargo.toml
@@ -14,10 +14,13 @@ license = "AGPL-3.0"
 
 anyhow = "1.0.38"
 ctrlc = "3.2.1"
+futures-util = "0.3.9"
+hex = "0.4.3"
 ptth_file_server = { path = "../ptth_file_server_bin" }
 ptth_server = { path = "../ptth_server" }
 quic_demo = { path = "../../prototypes/quic_demo" }
 rusty_ulid = "0.10.1"
+sha2 = "0.9.8"
 tokio = { version = "1.8.1", features = ["full"] }
 tracing-subscriber = "0.2.16"
 tracing = "0.1.25"
diff --git a/crates/ptth_multi_call_server/src/download.rs b/crates/ptth_multi_call_server/src/download.rs
index 25891d5..364b26c 100644
--- a/crates/ptth_multi_call_server/src/download.rs
+++ b/crates/ptth_multi_call_server/src/download.rs
@@ -1,5 +1,9 @@
 use std::{
 	ffi::OsString,
+	io::{
+		self,
+		Write,
+	},
 	time::Duration,
 };
 
@@ -8,9 +12,28 @@ use anyhow::{
 	bail,
 };
 
+use futures_util::StreamExt;
+
+use reqwest::{
+	StatusCode,
+};
+
+use sha2::{
+	Digest,
+	Sha512,
+};
+
+use tokio::{
+	sync::mpsc,
+	task::{
+		spawn,
+		spawn_blocking,
+	},
+};
+
 pub async fn main (args: &[OsString]) -> anyhow::Result <()> {
 	let mut url = None;
-	let mut sha512 = None;
+	let mut expected_sha512 = None;
 	
 	let mut args = args [1..].into_iter ();
 	
@@ -23,8 +46,9 @@ pub async fn main (args: &[OsString]) -> anyhow::Result <()> {
 		match arg.to_str ().ok_or_else (|| anyhow! ("All arguments must be valid UTF-8"))? 
 		{
 			"--help" => println! ("For now, just look at the source code"),
-			"--sha512" => {
-				sha512 = args.next ();
+			"--expect-sha512" => {
+				let expected = args.next ().ok_or_else (|| anyhow! ("--expect-sha512 needs an argument"))?;
+				expected_sha512 = Some (expected.to_str ().ok_or_else (|| anyhow! ("--expect-sha512's argument must be valid Unicode"))?);
 			}
 			arg => {
 				url = Some (arg);
@@ -45,5 +69,54 @@ pub async fn main (args: &[OsString]) -> anyhow::Result <()> {
 	.connect_timeout (Duration::from_secs (30))
 	.build ()?;
 	
+	let resp = client.get (url)
+	.send ().await?;
+	
+	if resp.status () != StatusCode::OK {
+		bail! ("Expected 200 OK, got {}", resp.status ());
+	}
+	
+	let mut resp_stream = resp.bytes_stream ();
+	
+	// The hasher is owned by a task because it makes ownership simpler
+	let (mut hash_tx, mut hash_rx) = mpsc::channel (1);
+	
+	let hasher_task = spawn_blocking (move || {
+		let mut hasher = Sha512::new ();
+		
+		while let Some (chunk) = tokio::runtime::Handle::current ().block_on (hash_rx.recv ()) {
+			hasher.update (&chunk);
+		}
+		
+		anyhow::Result::<_>::Ok (hasher.finalize ())
+	});
+	
+	while let Some (chunk) = resp_stream.next ().await {
+		let chunk = chunk?;
+		
+		hash_tx.send (chunk.clone ()).await?;
+		
+		{
+			let chunk = chunk.clone ();
+			spawn_blocking (move || {
+				io::stdout ().write_all (&chunk)?;
+				anyhow::Result::<_>::Ok (())
+			}).await??;
+		}
+	}
+	
+	drop (hash_tx);
+	
+	let hash = hasher_task.await??;
+	
+	let actual_sha512 = hex::encode (&hash);
+	
+	match expected_sha512 {
+		None => eprintln! ("Actual SHA512 = {}", actual_sha512),
+		Some (expected) => if ! actual_sha512.starts_with (&expected) {
+			bail! ("Expected SHA512 prefix {}, actual SHA512 {}", expected, actual_sha512);
+		},
+	}
+	
 	Ok (())
 }