From 89c83291320732c3993225a568ccce2f8d390b06 Mon Sep 17 00:00:00 2001
From: paibamboo <gavinsitti@hotmail.com>
Date: Wed, 23 Oct 2019 15:17:16 +0700
Subject: [PATCH] feat: enum sort keys rule

---
 README.md                                     |  3 ++
 src/enumSortKeysRule.ts                       | 42 +++++++++++++++++++
 .../rules/enum-sort-keys/default/test.ts.lint | 25 +++++++++++
 test/rules/enum-sort-keys/default/tslint.json |  8 ++++
 tslint-rules.json                             |  1 +
 5 files changed, 79 insertions(+)
 create mode 100644 src/enumSortKeysRule.ts
 create mode 100644 test/rules/enum-sort-keys/default/test.ts.lint
 create mode 100644 test/rules/enum-sort-keys/default/tslint.json

diff --git a/README.md b/README.md
index d36766c..8442d79 100644
--- a/README.md
+++ b/README.md
@@ -33,6 +33,9 @@ Initially you should:
   called. Still, as you see, we need to provide string literal as arugments due to typescript limitation, if we provide
   any string variable, the type will be deduced to just `string`. This rule enforces 2nd, 3rd, and 4th argument to be
   the concatenation of the first argument string and `_PENDING`, `_FULFILLED`, and `_REJECTED` respectively.
+### `enum-sort-keys`
+  - Same as [object-literal-sort-keys](https://palantir.github.io/tslint/rules/object-literal-sort-keys/) but applied to
+  enum keys
 ### `import-react`
   - Specify how you should import `react`. Either `import *` or `import React`.
   - Rule options:
diff --git a/src/enumSortKeysRule.ts b/src/enumSortKeysRule.ts
new file mode 100644
index 0000000..8063ed6
--- /dev/null
+++ b/src/enumSortKeysRule.ts
@@ -0,0 +1,42 @@
+import * as Lint from "tslint";
+import * as ts from "typescript";
+
+class EnumSortKeysRule extends Lint.AbstractWalker {
+  public walk(sourceFile: ts.SourceFile): void {
+    const cb = (node: ts.Node): void => {
+      if (ts.isEnumDeclaration(node)) {
+        const properties = node.members.map((member) => member.getText());
+        const unsortedIndex = this.getUnsortedIndex(properties);
+        if (unsortedIndex !== -1) {
+          const member = node.members[unsortedIndex];
+          this.addFailureAtNode(member.name, `The key "${member.name.getText()}" is not sorted alphabetically`);
+        }
+      }
+      return ts.forEachChild(node, cb);
+    };
+    return ts.forEachChild(sourceFile, cb);
+  }
+
+  private getUnsortedIndex(strs: string[], startIndex: number = 0): number {
+    if (strs.length < 2 || strs.length === startIndex + 1) {
+      return -1;
+    }
+    if (strs[startIndex] > strs[startIndex + 1]) {
+      return startIndex;
+    }
+    return this.getUnsortedIndex(strs, startIndex + 1);
+  }
+}
+
+// tslint:disable-next-line:export-name max-classes-per-file
+export class Rule extends Lint.Rules.AbstractRule {
+  public apply(sourceFile: ts.SourceFile): Lint.RuleFailure[] {
+    return this.applyWithWalker(
+      new EnumSortKeysRule(
+        sourceFile,
+        "enum-sort-keys",
+        undefined
+      )
+    );
+  }
+}
diff --git a/test/rules/enum-sort-keys/default/test.ts.lint b/test/rules/enum-sort-keys/default/test.ts.lint
new file mode 100644
index 0000000..411a160
--- /dev/null
+++ b/test/rules/enum-sort-keys/default/test.ts.lint
@@ -0,0 +1,25 @@
+enum Character {
+    AAA = "aaa",
+    BBB = "bbb",
+    CCC = "ccc"
+}
+
+enum Character {
+    AAA = "aaa",
+    CCC = "ccc",
+    ~~~           [The key "CCC" is not sorted alphabetically]
+    BBB = "bbb"
+}
+
+enum Number {
+    ONE,
+    THREE,
+    TWO
+}
+
+enum Number {
+    ONE,
+    TWO,
+    ~~~   [The key "TWO" is not sorted alphabetically]
+    THREE
+}
diff --git a/test/rules/enum-sort-keys/default/tslint.json b/test/rules/enum-sort-keys/default/tslint.json
new file mode 100644
index 0000000..f97bd32
--- /dev/null
+++ b/test/rules/enum-sort-keys/default/tslint.json
@@ -0,0 +1,8 @@
+{
+  "rulesDirectory": [
+    "../../../../lib"
+  ],
+  "rules": {
+    "enum-sort-keys": true
+  }
+}
diff --git a/tslint-rules.json b/tslint-rules.json
index 0881159..913649c 100644
--- a/tslint-rules.json
+++ b/tslint-rules.json
@@ -1,6 +1,7 @@
 {
   "rulesDirectory": "./lib",
   "rules": {
+    "enum-sort-keys": true,
     "import-react": [true, {"type": "star"}],
     "hex-format": true,
     "interface-sort-keys": true