Suggest valid message or constructor name, when misspelled

crates/transcode/Cargo.toml

@@ -36,6 +36,7 @@ scale-info = { version = "2.4.0", default-features = false, features = ["derive"
 serde = { version = "1.0.159", default-features = false, features = ["derive"] }
 serde_json = "1.0.95"
 thiserror = "1.0.40"
+strsim = "0.10.0"
 
 [dev-dependencies]
 assert_matches = "1.5.0"

crates/transcode/src/lib.rs

@@ -127,6 +127,7 @@ use ink_metadata::{
     InkProject,
     MessageSpec,
 };
+use itertools::Itertools;
 use scale::{
     Compact,
     Decode,
@@ -140,6 +141,7 @@ use scale_info::{
     Field,
 };
 use std::{
+    cmp::Ordering,
     fmt::Debug,
     path::Path,
 };
@@ -151,6 +153,24 @@ pub struct ContractMessageTranscoder {
     transcoder: Transcoder,
 }
 
+/// Find strings from an iterable of `possible_values` similar to a given value `v`
+/// Returns a Vec of all possible values that exceed a similarity threshold
+/// sorted by ascending similarity, most similar comes last
+/// Extracted from https://github.com/clap-rs/clap/blob/v4.3.4/clap_builder/src/parser/features/suggestions.rs#L11-L26
+fn did_you_mean<T, I>(v: &str, possible_values: I) -> Vec<String>
+where
+    T: AsRef<str>,
+    I: IntoIterator<Item = T>,
+{
+    let mut candidates: Vec<(f64, String)> = possible_values
+        .into_iter()
+        .map(|pv| (strsim::jaro(v, pv.as_ref()), pv.as_ref().to_owned()))
+        .filter(|(confidence, _)| *confidence > 0.7)
+        .collect();
+    candidates.sort_by(|a, b| a.0.partial_cmp(&b.0).unwrap_or(Ordering::Equal));
+    candidates.into_iter().map(|(_, pv)| pv).collect()
+}
+
 impl ContractMessageTranscoder {
     pub fn new(metadata: InkProject) -> Self {
         let transcoder = TranscoderBuilder::new(metadata.registry())
@@ -200,9 +220,18 @@ impl ContractMessageTranscoder {
             ))
             }
             (None, None) => {
+                let constructors = self.constructors().map(|c| c.label());
+                let messages = self.messages().map(|c| c.label());
+                let possible_values: Vec<_> = constructors.chain(messages).collect();
+                let help_txt = did_you_mean(name, possible_values.clone())
+                    .first()
+                    .map(|suggestion| format!("Did you mean '{}'?", suggestion))
+                    .unwrap_or_else(|| {
+                        format!("Should be one of: {}", possible_values.iter().join(", "))
+                    });
+
                 return Err(anyhow::anyhow!(
-                    "No constructor or message with the name '{}' found",
-                    name
+                    "No constructor or message with the name '{name}' found.\n{help_txt}",
                 ))
             }
         };
@@ -538,6 +567,16 @@ mod tests {
         Ok(())
     }
 
+    #[test]
+    fn encode_misspelled_arg() {
+        let metadata = generate_metadata();
+        let transcoder = ContractMessageTranscoder::new(metadata);
+        assert_eq!(
+            transcoder.encode("fip", ["true"]).unwrap_err().to_string(),
+            "No constructor or message with the name 'fip' found.\nDid you mean 'flip'?"
+        );
+    }
+
     #[test]
     fn encode_mismatching_args_length() {
         let metadata = generate_metadata();