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Frontend-Learner/node_modules/eslint-plugin-unicorn/rules/no-nested-ternary.js

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+import {isParenthesized} from '@eslint-community/eslint-utils';
+
+const MESSAGE_ID_TOO_DEEP = 'too-deep';
+const MESSAGE_ID_SHOULD_PARENTHESIZED = 'should-parenthesized';
+const messages = {
+	[MESSAGE_ID_TOO_DEEP]: 'Do not nest ternary expressions.',
+	[MESSAGE_ID_SHOULD_PARENTHESIZED]: 'Nested ternary expression should be parenthesized.',
+};
+
+/** @param {import('eslint').Rule.RuleContext} context */
+const create = context => ({
+	ConditionalExpression(node) {
+		if ([
+			node.test,
+			node.consequent,
+			node.alternate,
+		].some(node => node.type === 'ConditionalExpression')) {
+			return;
+		}
+
+		const {sourceCode} = context;
+		const ancestors = sourceCode.getAncestors(node).toReversed();
+		const nestLevel = ancestors.findIndex(node => node.type !== 'ConditionalExpression');
+
+		if (nestLevel === 1 && !isParenthesized(node, sourceCode)) {
+			return {
+				node,
+				messageId: MESSAGE_ID_SHOULD_PARENTHESIZED,
+				fix: fixer => [
+					fixer.insertTextBefore(node, '('),
+					fixer.insertTextAfter(node, ')'),
+				],
+			};
+		}
+
+		// Nesting more than one level not allowed
+		if (nestLevel > 1) {
+			return {
+				node: nestLevel > 2 ? ancestors[nestLevel - 3] : node,
+				messageId: MESSAGE_ID_TOO_DEEP,
+			};
+		}
+	},
+});
+
+/** @type {import('eslint').Rule.RuleModule} */
+const config = {
+	create,
+	meta: {
+		type: 'suggestion',
+		docs: {
+			description: 'Disallow nested ternary expressions.',
+			recommended: true,
+		},
+		fixable: 'code',
+		messages,
+	},
+};
+
+export default config;