/**
   * @fileoverview Rule to disallow assignments to native objects or read-only global variables
   * @author Ilya Volodin
   */
  
  "use strict";
  
  //------------------------------------------------------------------------------
  // Rule Definition
  //------------------------------------------------------------------------------
  
  module.exports = {
      meta: {
          docs: {
              description: "disallow assignments to native objects or read-only global variables",
              category: "Best Practices",
              recommended: true
          },
  
          schema: [
              {
                  type: "object",
                  properties: {
                      exceptions: {
                          type: "array",
                          items: { type: "string" },
                          uniqueItems: true
                      }
                  },
                  additionalProperties: false
              }
          ]
      },
  
      create(context) {
          const config = context.options[0];
          const exceptions = (config && config.exceptions) || [];
  
          /**
           * Reports write references.
           * @param {Reference} reference - A reference to check.
           * @param {int} index - The index of the reference in the references.
           * @param {Reference[]} references - The array that the reference belongs to.
           * @returns {void}
           */
          function checkReference(reference, index, references) {
              const identifier = reference.identifier;
  
              if (reference.init === false &&
                  reference.isWrite() &&
  
                  // Destructuring assignments can have multiple default value,
                  // so possibly there are multiple writeable references for the same identifier.
                  (index === 0 || references[index - 1].identifier !== identifier)
              ) {
                  context.report({
                      node: identifier,
                      message: "Read-only global '{{name}}' should not be modified.",
                      data: identifier
                  });
              }
          }
  
          /**
           * Reports write references if a given variable is read-only builtin.
           * @param {Variable} variable - A variable to check.
           * @returns {void}
           */
          function checkVariable(variable) {
              if (variable.writeable === false && exceptions.indexOf(variable.name) === -1) {
                  variable.references.forEach(checkReference);
              }
          }
  
          return {
              Program() {
                  const globalScope = context.getScope();
  
                  globalScope.variables.forEach(checkVariable);
              }
          };
      }
  };