/**
 * @fileoverview Rule to flag variable leak in CatchClauses in IE 8 and earlier
 * @author Ian Christian Myers
 * @deprecated in ESLint v5.1.0
 */

'use strict';

//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------

const astUtils = require('./utils/ast-utils');

//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------

/** @type {import('../types').Rule.RuleModule} */
module.exports = {
  meta: {
    type: 'suggestion',

    docs: {
      description:
        'Disallow `catch` clause parameters from shadowing variables in the outer scope',
      recommended: false,
      url: 'https://eslint.org/docs/latest/rules/no-catch-shadow',
    },

    deprecated: {
      message: 'This rule was renamed.',
      url: 'https://eslint.org/blog/2018/07/eslint-v5.1.0-released/',
      deprecatedSince: '5.1.0',
      availableUntil: null,
      replacedBy: [
        {
          rule: {
            name: 'no-shadow',
            url: 'https://eslint.org/docs/rules/no-shadow',
          },
        },
      ],
    },
    schema: [],

    messages: {
      mutable: "Value of '{{name}}' may be overwritten in IE 8 and earlier.",
    },
  },

  create(context) {
    const sourceCode = context.sourceCode;

    //--------------------------------------------------------------------------
    // Helpers
    //--------------------------------------------------------------------------

    /**
     * Check if the parameters are been shadowed
     * @param {Object} scope current scope
     * @param {string} name parameter name
     * @returns {boolean} True is its been shadowed
     */
    function paramIsShadowing(scope, name) {
      return astUtils.getVariableByName(scope, name) !== null;
    }

    //--------------------------------------------------------------------------
    // Public API
    //--------------------------------------------------------------------------

    return {
      'CatchClause[param!=null]'(node) {
        let scope = sourceCode.getScope(node);

        /*
         * When ecmaVersion >= 6, CatchClause creates its own scope
         * so start from one upper scope to exclude the current node
         */
        if (scope.block === node) {
          scope = scope.upper;
        }

        if (paramIsShadowing(scope, node.param.name)) {
          context.report({
            node,
            messageId: 'mutable',
            data: { name: node.param.name },
          });
        }
      },
    };
  },
};