/**
   * @fileoverview Rule to flag variable leak in CatchClauses in IE 8 and earlier
   * @author Ian Christian Myers
   */
  
  "use strict";
  
  //------------------------------------------------------------------------------
  // Requirements
  //------------------------------------------------------------------------------
  
  const astUtils = require("../ast-utils");
  
  //------------------------------------------------------------------------------
  // Rule Definition
  //------------------------------------------------------------------------------
  
  module.exports = {
      meta: {
          docs: {
              description: "disallow `catch` clause parameters from shadowing variables in the outer scope",
              category: "Variables",
              recommended: false
          },
  
          schema: []
      },
  
      create(context) {
  
          //--------------------------------------------------------------------------
          // 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(node) {
                  let scope = context.getScope();
  
                  // When blockBindings is enabled, 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, message: "Value of '{{name}}' may be overwritten in IE 8 and earlier.", data: { name: node.param.name } });
                  }
              }
          };
  
      }
  };