Create euphoxide-bot crate

euphoxide-bot/src/command/clap.rs

@@ -0,0 +1,187 @@
+//! [`clap`]-based commands.
+
+use async_trait::async_trait;
+use clap::{CommandFactory, Parser};
+use euphoxide::api::Message;
+
+use crate::bot::Bot;
+
+use super::{Command, Context, Info, Propagate};
+
+#[async_trait]
+pub trait ClapCommand<S, E> {
+    type Args;
+
+    async fn execute(
+        &self,
+        args: Self::Args,
+        msg: &Message,
+        ctx: &Context,
+        bot: &Bot<S, E>,
+    ) -> Result<Propagate, E>;
+}
+
+/// Parse bash-like quoted arguments separated by whitespace.
+///
+/// Outside of quotes, the backslash either escapes the next character or forms
+/// an escape sequence. \n is a newline, \r a carriage return and \t a tab.
+/// TODO Escape sequences
+///
+/// Special characters like the backslash and whitespace can also be quoted
+/// using double quotes. Within double quotes, \" escapes a double quote and \\
+/// escapes a backslash. Other occurrences of \ have no special meaning.
+fn parse_quoted_args(text: &str) -> Result<Vec<String>, &'static str> {
+    let mut args = vec![];
+    let mut arg = String::new();
+    let mut arg_exists = false;
+
+    let mut quoted = false;
+    let mut escaped = false;
+    for c in text.chars() {
+        if quoted {
+            match c {
+                '\\' if escaped => {
+                    arg.push('\\');
+                    escaped = false;
+                }
+                '"' if escaped => {
+                    arg.push('"');
+                    escaped = false;
+                }
+                c if escaped => {
+                    arg.push('\\');
+                    arg.push(c);
+                    escaped = false;
+                }
+                '\\' => escaped = true,
+                '"' => quoted = false,
+                c => arg.push(c),
+            }
+        } else {
+            match c {
+                c if escaped => {
+                    arg.push(c);
+                    arg_exists = true;
+                    escaped = false;
+                }
+                c if c.is_whitespace() => {
+                    if arg_exists {
+                        args.push(arg);
+                        arg = String::new();
+                        arg_exists = false;
+                    }
+                }
+                '\\' => escaped = true,
+                '"' => {
+                    quoted = true;
+                    arg_exists = true;
+                }
+                c => {
+                    arg.push(c);
+                    arg_exists = true;
+                }
+            }
+        }
+    }
+
+    if quoted {
+        return Err("Unclosed trailing quote");
+    }
+    if escaped {
+        return Err("Unfinished trailing escape");
+    }
+
+    if arg_exists {
+        args.push(arg);
+    }
+
+    Ok(args)
+}
+
+pub struct Clap<C>(pub C);
+
+#[async_trait]
+impl<S, E, C> Command<S, E> for Clap<C>
+where
+    S: Send + Sync,
+    E: From<euphoxide::Error>,
+    C: ClapCommand<S, E> + Sync,
+    C::Args: Parser + Send,
+{
+    fn info(&self, _ctx: &Context) -> Info {
+        Info {
+            description: C::Args::command().get_about().map(|s| s.to_string()),
+            ..Info::default()
+        }
+    }
+
+    async fn execute(
+        &self,
+        arg: &str,
+        msg: &Message,
+        ctx: &Context,
+        bot: &Bot<S, E>,
+    ) -> Result<Propagate, E> {
+        let mut args = match parse_quoted_args(arg) {
+            Ok(args) => args,
+            Err(err) => {
+                ctx.reply_only(msg.id, err).await?;
+                return Ok(Propagate::No);
+            }
+        };
+
+        // Hacky, but it should work fine in most cases
+        let usage = msg.content.strip_suffix(arg).unwrap_or("<command>").trim();
+        args.insert(0, usage.to_string());
+
+        let args = match C::Args::try_parse_from(args) {
+            Ok(args) => args,
+            Err(err) => {
+                ctx.reply_only(msg.id, format!("{}", err.render())).await?;
+                return Ok(Propagate::No);
+            }
+        };
+
+        self.0.execute(args, msg, ctx, bot).await
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::parse_quoted_args;
+
+    fn assert_quoted(raw: &str, parsed: &[&str]) {
+        let parsed = parsed.iter().map(|s| s.to_string()).collect();
+        assert_eq!(parse_quoted_args(raw), Ok(parsed))
+    }
+
+    #[test]
+    fn test_parse_quoted_args() {
+        assert_quoted("foo bar baz", &["foo", "bar", "baz"]);
+        assert_quoted("    foo     bar     baz    ", &["foo", "bar", "baz"]);
+        assert_quoted("foo\\ ba\"r ba\"z", &["foo bar baz"]);
+        assert_quoted(
+            "It's a nice day, isn't it?",
+            &["It's", "a", "nice", "day,", "isn't", "it?"],
+        );
+
+        // Trailing whitespace
+        assert_quoted("a ", &["a"]);
+        assert_quoted("a\\ ", &["a "]);
+        assert_quoted("a\\  ", &["a "]);
+
+        // Zero-length arguments
+        assert_quoted("a \"\" b \"\"", &["a", "", "b", ""]);
+        assert_quoted("a \"\" b \"\" ", &["a", "", "b", ""]);
+
+        // Backslashes in quotes
+        assert_quoted("\"a \\b \\\" \\\\\"", &["a \\b \" \\"]);
+
+        // Unclosed quotes and unfinished escapes
+        assert!(parse_quoted_args("foo 'bar \"baz").is_err());
+        assert!(parse_quoted_args("foo \"bar baz").is_err());
+        assert!(parse_quoted_args("foo \"bar 'baz").is_err());
+        assert!(parse_quoted_args("foo \\").is_err());
+        assert!(parse_quoted_args("foo 'bar\\").is_err());
+    }
+}