Execute some languages via coliru

src/main.rs

@@ -4,6 +4,7 @@ extern crate calc;
 extern crate ddg;
 extern crate regex;
 #[macro_use] extern crate lazy_static;
+extern crate reqwest;
 
 use serenity::client::{Client, EventHandler};
 use serenity::framework::standard::{StandardFramework, help_commands};
@@ -31,11 +32,11 @@ pub fn main() {
             .case_insensitivity(true)
             .on_mention(true))
         .help(help_commands::with_embeds)
-        .before(|_context, _message, command| { println!("Executing {}!", command); true })
+        .before(|_context, message, _command| { println!("> {}", message.content); true })
         .command("ping", |c| c.cmd(ping).desc("Says Pong.").known_as("test"))
         .command("search", |c| c.cmd(search).desc("Executes a search using DuckDuckGo.").known_as("ddg"))
         .command("eval", |c| c.cmd(eval).desc("Evaluates an arithmetic expression.").known_as("calc"))
-        .command("exec", |c| c.cmd(exec).desc("DO NOT USE"))
+        .command("exec", |c| c.cmd(exec).desc("Executes code passed in codeblock with language set via Coliru. Supported languages: python, shell."))
         .command("eval-polish", |c| c.cmd(eval_polish).desc("Evaluates a Polish-notation arithmetic expression.")));
 
     if let Err(why) = client.start() {
@@ -80,6 +81,48 @@ command!(eval_polish(_context, message, args) {
     send_result(message, &calc::eval_polish(&expr))?;
 });
 
+fn execute_coliru(command: &str, code: &str) -> Result<String, reqwest::Error> {
+    lazy_static! {
+        static ref CLIENT: reqwest::Client = reqwest::Client::new();
+    }
+
+    let mut data = std::collections::HashMap::new();
+    data.insert("src", code);
+    data.insert("cmd", command);
+
+    let mut res = CLIENT.post("http://coliru.stacked-crooked.com/compile")
+        .json(&data)
+        .send()?;
+
+    Ok(res.text()?)
+}
+
+// Thanks StackOverflow!
+fn truncate(s: &str, max_chars: usize) -> &str {
+    match s.char_indices().nth(max_chars) {
+        None => s,
+        Some((idx, _)) => &s[..idx],
+    }
+}
+
+fn to_code_block(s: &str) -> String {
+    format!("```\n{}\n```", truncate(s, 1990)) // Discord only allows 2000 Unicode codepoints per message
+}
+
+fn execute_and_respond(channel: &ChannelId, command: &str, code: &str) -> Result<(), serenity::Error> {
+    let coliru_result = execute_coliru(command, code);
+
+    match coliru_result {
+        Ok(stdout) => {
+            channel.send_message(|m|
+                m.content(&to_code_block(&stdout)))?;
+        },
+        Err(e) => send_error(channel, &format!("{}", e))?
+    }
+
+    Ok(())
+}
+
 command!(exec(_context, message) {
     lazy_static! {
         static ref RE: Regex = Regex::new("(?s)^.*exec.*```([a-zA-Z0-9_\\-+]+)\n(.+)\n```").unwrap();
@@ -96,10 +139,16 @@ command!(exec(_context, message) {
 
     let code = &captures[2];
     let lang = &captures[1];
+    let channel = &message.channel_id;
 
     match lang {
-        _ => send_error(&message.channel_id, &format!("Unknown language `{}`.", lang))?
-    };
+        "test" => execute_and_respond(channel, "echo Hello, World!", ""),
+        "py" | "python" => execute_and_respond(channel, "mv main.cpp main.py && python main.py", code),
+        "sh" | "shell" => execute_and_respond(channel, "mv main.cpp main.sh && sh main.sh", code),
+        "lua" => execute_and_respond(channel, "mv main.cpp main.lua && lua main.lua", code),
+        "haskell" | "hs" => execute_and_respond(channel, "mv main.cpp main.hs && runhaskell main.hs", code),
+        _ => send_error(channel, &format!("Unknown language `{}`.", lang))
+    }?;
 });
 
 // BELOW THIS LINE BE DRAGONS
@@ -154,6 +203,7 @@ command!(search(_context, message, args) {
     let query = args.multiple::<String>()?.join(" ");
     let result = ddg::Query::new(query.as_str(), "autobotrobot").no_html().execute()?;
     let channel = &message.channel_id;
+
     match result.response_type {
         ddg::Type::Article | ddg::Type::Name => send_search_result(channel, SearchResult {
             title: query,