From adaba186a75668f451c137c6299f5141e98e4150 Mon Sep 17 00:00:00 2001
From: Boris Cherny <boris@performancejs.com>
Date: Tue, 15 Nov 2016 10:29:08 -0800
Subject: [PATCH] simplify usage, better error message

---
 README.md                       |  5 +----
 noCircularImportsRule.ts        | 26 ++++++++++++++++++--------
 package.json                    |  4 ++--
 tslint-no-circular-imports.json |  6 ++++++
 4 files changed, 27 insertions(+), 14 deletions(-)
 create mode 100644 tslint-no-circular-imports.json

diff --git a/README.md b/README.md
index 3e8432a..d6c85d8 100644
--- a/README.md
+++ b/README.md
@@ -18,10 +18,7 @@ Add the following to your tslint.json:
 
 ```json
 {
-  "rulesDirectory": "node_modules/tslint-no-circular-imports",
-  "rules": {
-    "no-circular-imports": true
-  }
+  "extends": ["tslint-no-circular-imports"]
 }
 ```
 
diff --git a/noCircularImportsRule.ts b/noCircularImportsRule.ts
index 05dfa5b..5a43b29 100644
--- a/noCircularImportsRule.ts
+++ b/noCircularImportsRule.ts
@@ -1,8 +1,9 @@
+import { basename } from 'path'
 import * as ts from 'typescript'
 import * as Lint from 'tslint/lib/lint'
 
 export class Rule extends Lint.Rules.AbstractRule {
-  static FAILURE_STRING = 'circular import detected'
+  static FAILURE_STRING = 'Circular import detected'
 
   static metadata: Lint.IRuleMetadata = {
     ruleName: 'no-circular-imports',
@@ -37,7 +38,11 @@ class NoCircularImportsWalker extends Lint.RuleWalker {
 
     // check for cycles
     if (this.hasCycle(thisModuleName)) {
-      this.addFailure(this.createFailure(node.getStart(), node.getWidth(), Rule.FAILURE_STRING))
+      this.addFailure(
+        this.createFailure(node.getStart(), node.getWidth(), `${Rule.FAILURE_STRING}: ${
+          this.getCycle(thisModuleName).concat(thisModuleName).map(_ => basename(_)).join(' -> ')
+        }`)
+      )
     }
 
     super.visitImportDeclaration(node)
@@ -53,12 +58,17 @@ class NoCircularImportsWalker extends Lint.RuleWalker {
     imports.get(thisModuleName)!.add(importCanonicalName)
   }
 
-  private hasCycle(moduleName: string, accumulator: string[] = []): boolean {
-    if (!imports.get(moduleName)) return false
-    if (accumulator.includes(moduleName)) return true
-    return Array.from(imports.get(moduleName)!.values()).some(_ =>
-      this.hasCycle(_, accumulator.concat(moduleName))
-    )
+  private hasCycle(moduleName: string): boolean {
+    return this.getCycle(moduleName).length > 0
+  }
+
+  private getCycle(moduleName: string, accumulator: string[] = []): string[] {
+    if (!imports.get(moduleName)) return []
+    if (accumulator.includes(moduleName)) return accumulator
+    return Array.from(imports.get(moduleName) !.values()).reduce((_prev, _) => {
+      const c = this.getCycle(_, accumulator.concat(moduleName))
+      return c.length ? c : []
+    }, [] as string[])
   }
 
 }
\ No newline at end of file
diff --git a/package.json b/package.json
index 2e58f10..a5da8ab 100644
--- a/package.json
+++ b/package.json
@@ -1,8 +1,8 @@
 {
   "name": "tslint-no-circular-imports",
-  "version": "0.0.2",
+  "version": "0.0.3",
   "description": "TSLint plugin to detect and warn about cicular imports",
-  "main": "noCircularImportsRule.js",
+  "main": "./tslint-no-circular-imports.json",
   "scripts": {
     "build": "npm run build-sources && npm test",
     "build-sources": "tsc -p ./tsconfig.json",
diff --git a/tslint-no-circular-imports.json b/tslint-no-circular-imports.json
new file mode 100644
index 0000000..74b89de
--- /dev/null
+++ b/tslint-no-circular-imports.json
@@ -0,0 +1,6 @@
+{
+  "rulesDirectory": "./",
+  "rules": {
+    "no-circular-imports": true
+  }
+}