feat: improved user experience for detached instances with prefix matching and suggestions

src/packages/cli/src/cli.ts

@@ -164,11 +164,22 @@ if (argv.action === "start") {
 } else if (argv.action === "stop") {
   const instanceName = argv.name;
 
-  stopDetachedInstance(instanceName).then(instanceFound => {
-    if (instanceFound) {
-      console.log("Instance stopped");
+  stopDetachedInstance(instanceName).then(instanceOrSuggestions => {
+    if ("instance" in instanceOrSuggestions) {
+      const highlightedName = porscheColor(instanceOrSuggestions.instance.name);
+      console.log(`${highlightedName} stopped.`);
     } else {
-      console.error("Instance not found");
+      process.exitCode = 1;
+      console.log(`${porscheColor(instanceName)} not found.`);
+      if (instanceOrSuggestions.suggestions?.length > 0) {
+        console.log();
+        console.log("Did you mean:");
+        console.log(
+          instanceOrSuggestions.suggestions
+            .map(name => " - " + porscheColor(name))
+            .join("\n")
+        );
+      }
     }
   });
 } else if (argv.action === "start-detached") {
@@ -181,7 +192,8 @@ if (argv.action === "start") {
     })
     .catch(err => {
       // the child process would have output its error to stdout, so no need to
-      // output anything more
+      // do anything more other than set the exitCode
+      process.exitCode = 1;
     });
 } else if (argv.action === "list") {
   getDetachedInstances().then(instances => {

src/packages/cli/src/detach.ts

@@ -19,6 +19,8 @@ export type DetachedInstance = {
   version: string;
 };
 
+const MAX_SUGGESTIONS = 4;
+const MAX_LEVENSHTEIN_DISTANCE = 10;
 const FILE_ENCODING = "utf8";
 const START_ERROR =
   "An error occurred spawning a detached instance of Ganache:";
@@ -53,6 +55,12 @@ export async function removeDetachedInstanceFile(
   return false;
 }
 
+// A fuzzy matched detached instance(s). Either a strong match as instance,
+// or a list of suggestions.
+type InstanceOrSuggestions =
+  | { instance: DetachedInstance }
+  | { suggestions: string[] };
+
 /**
  * Attempts to stop a detached instance with the specified instance name by
  * sending a SIGTERM signal. Returns a boolean indicating whether the process
@@ -61,25 +69,127 @@ export async function removeDetachedInstanceFile(
  *
  * Note: This does not guarantee that the instance actually stops.
  * @param  {string} instanceName
- * @returns boolean indicating whether the instance was found.
+ * @returns {InstanceOrSuggestions} an object containing either the stopped
+ * `instance`, or `suggestions` for similar instance names
  */
 export async function stopDetachedInstance(
   instanceName: string
-): Promise<boolean> {
+): Promise<InstanceOrSuggestions> {
+  let instance;
+
   try {
-    // getDetachedInstanceByName() throws if the instance file is not found or
-    // cannot be parsed
-    const instance = await getDetachedInstanceByName(instanceName);
+    instance = await getDetachedInstanceByName(instanceName);
+  } catch {
+    const similarInstances = await getSimilarInstanceNames(instanceName);
+
+    if ("match" in similarInstances) {
+      try {
+        instance = await getDetachedInstanceByName(similarInstances.match);
+      } catch (err) {
+        if ((err as NodeJS.ErrnoException).code === "ENOENT") {
+          // The instance file was removed between the call to
+          // `getSimilarInstanceNames` and `getDetachedInstancesByName`, but we
+          // didn't get suggestions (although some may exist). We _could_
+          // reiterate stopDetachedInstance but that seems messy. Let's just
+          // tell the user the instance wasn't found, and be done with it.
+          return {
+            suggestions: []
+          };
+        }
+        throw err;
+      }
+    } else {
+      return { suggestions: similarInstances.suggestions };
+    }
+  }
 
+  if (instance) {
     // process.kill() throws if the process was not found (or was a group
     // process in Windows)
-    process.kill(instance.pid, "SIGTERM");
+    try {
+      process.kill(instance.pid, "SIGTERM");
+    } catch (err) {
+      // process not found
+      // todo: log message saying that the process could not be found
+    } finally {
+      await removeDetachedInstanceFile(instance.name);
+      return { instance };
+    }
+  }
+}
+
+/**
+ * Find instances with names similar to `instanceName`.
+ *
+ * If there is a single instance with an exact prefix match, it is returned as
+ * the `match` property in the result. Otherwise, up to `MAX_SUGGESTIONS` names
+ * that are similar to `instanceName` are returned as `suggestions`. Names with
+ * an exact prefix match are prioritized, followed by increasing Levenshtein
+ * distance, up to a maximum distance of `MAX_LEVENSHTEIN_DISTANCE`.
+ * @param {string} instanceName the name for which similarly named instance will
+ * be searched
+ * @returns {{ match: string } | { suggestions: string[] }} an object
+ * containiner either a single exact `match` or a number of `suggestions`
+ */
+async function getSimilarInstanceNames(
+  instanceName: string
+): Promise<{ match: string } | { suggestions: string[] }> {
+  const filenames: string[] = [];
+  try {
+    const parsedPaths = (
+      await fsPromises.readdir(dataPath, { withFileTypes: true })
+    ).map(file => path.parse(file.name));
+
+    for (const { ext, name } of parsedPaths) {
+      if (ext === ".json") {
+        filenames.push(name);
+      }
+    }
   } catch (err) {
-    return false;
-  } finally {
-    await removeDetachedInstanceFile(instanceName);
+    if ((err as NodeJS.ErrnoException).code === "ENOENT") {
+      // instances directory does not exist, so there can be no suggestions
+      return { suggestions: [] };
+    }
+  }
+
+  const prefixMatches = [];
+  for (const name of filenames) {
+    if (name.startsWith(instanceName)) {
+      prefixMatches.push(name);
+    }
+  }
+
+  if (prefixMatches.length === 1) {
+    return { match: prefixMatches[0] };
+  }
+
+  let suggestions: string[];
+  if (prefixMatches.length >= MAX_SUGGESTIONS) {
+    suggestions = prefixMatches;
+  } else {
+    const similar = [];
+
+    for (const name of filenames) {
+      if (!prefixMatches.some(m => m === name)) {
+        const distance = levenshteinDistance(instanceName, name);
+        if (distance <= MAX_LEVENSHTEIN_DISTANCE) {
+          similar.push({
+            name,
+            distance
+          });
+        }
+      }
+    }
+    similar.sort((a, b) => a.distance - b.distance);
+
+    suggestions = similar.map(s => s.name);
+    // matches should be at the start of the suggestions array
+    suggestions.splice(0, 0, ...prefixMatches);
   }
-  return true;
+
+  return {
+    suggestions: suggestions.slice(0, MAX_SUGGESTIONS)
+  };
 }
 
 /**
@@ -323,3 +433,44 @@ export function formatUptime(ms: number) {
 
   return isFuture ? `In ${duration}` : duration;
 }
+
+/**
+ * This function calculates the Levenshtein distance between two strings.
+ * Levenshtein distance is a measure of the difference between two strings,
+ * defined as the minimum number of edits (insertions, deletions or substitutions)
+ * required to transform one string into another.
+ *
+ * @param {string} a - The first string to compare.
+ * @param {string} b - The second string to compare.
+ * @return {number} The Levenshtein distance between the two strings.
+ */
+export function levenshteinDistance(a: string, b: string): number {
+  if (a.length === 0) return b.length;
+  if (b.length === 0) return a.length;
+
+  let matrix = [];
+
+  for (let i = 0; i <= b.length; i++) {
+    matrix[i] = [i];
+  }
+
+  for (let j = 0; j <= a.length; j++) {
+    matrix[0][j] = j;
+  }
+
+  for (let i = 1; i <= b.length; i++) {
+    for (let j = 1; j <= a.length; j++) {
+      if (b.charAt(i - 1) == a.charAt(j - 1)) {
+        matrix[i][j] = matrix[i - 1][j - 1];
+      } else {
+        matrix[i][j] = Math.min(
+          matrix[i - 1][j - 1] + 1,
+          matrix[i][j - 1] + 1,
+          matrix[i - 1][j] + 1
+        );
+      }
+    }
+  }
+
+  return matrix[b.length][a.length];
+}

src/packages/cli/tests/detach.test.ts

@@ -1,8 +1,66 @@
 import assert from "assert";
-import { formatUptime } from "../src/detach";
+import { formatUptime, levenshteinDistance } from "../src/detach";
 
 describe("@ganache/cli", () => {
   describe("detach", () => {
+    describe("levenshteinDistance", () => {
+      it("returns 0 for identical strings", () => {
+        const a = "hello";
+        const b = "hello";
+        const result = levenshteinDistance(a, b);
+
+        assert.strictEqual(result, 0);
+      });
+
+      it("returns correct distance for different strings", () => {
+        const a = "hello";
+        const b = "world";
+        const result = levenshteinDistance(a, b);
+
+        assert.strictEqual(result, 4);
+      });
+
+      it("returns correct distance for strings of different lengths", () => {
+        const a = "hello";
+        const b = "hi";
+        const result = levenshteinDistance(a, b);
+
+        assert.strictEqual(result, 4);
+      });
+
+      it("returns correct distance for strings with additions", () => {
+        const a = "hello";
+        const b = "heBlAlo";
+        const result = levenshteinDistance(a, b);
+
+        assert.strictEqual(result, 2);
+      });
+
+      it("returns correct distance for strings with subtractions", () => {
+        const a = "hello";
+        const b = "hll";
+        const result = levenshteinDistance(a, b);
+
+        assert.strictEqual(result, 2);
+      });
+
+      it("returns correct distance for strings with substitutions", () => {
+        const a = "hello";
+        const b = "hAlAo";
+        const result = levenshteinDistance(a, b);
+
+        assert.strictEqual(result, 2);
+      });
+
+      it("returns correct distance for strings with addition, subtraction and substitution", () => {
+        const a = "hello world";
+        const b = "helloo wolB";
+        const result = levenshteinDistance(a, b);
+
+        assert.strictEqual(result, 3);
+      });
+    });
+
     describe("formatUptime()", () => {
       const durations: [number, string][] = [
         [0, "Just started"],