/**
   * @fileoverview Rule to flag use of alert, confirm, prompt
   * @author Nicholas C. Zakas
   * @copyright 2015 Mathias Schreck
   * @copyright 2013 Nicholas C. Zakas
   */
  "use strict";
  
  //------------------------------------------------------------------------------
  // Helpers
  //------------------------------------------------------------------------------
  
  /**
   * Checks if the given name is a prohibited identifier.
   * @param {string} name The name to check
   * @returns {boolean} Whether or not the name is prohibited.
   */
  function isProhibitedIdentifier(name) {
      return /^(alert|confirm|prompt)$/.test(name);
  }
  
  /**
   * Reports the given node and identifier name.
   * @param {RuleContext} context The ESLint rule context.
   * @param {ASTNode} node The node to report on.
   * @param {string} identifierName The name of the identifier.
   * @returns {void}
   */
  function report(context, node, identifierName) {
      context.report(node, "Unexpected {{name}}.", { name: identifierName });
  }
  
  /**
   * Returns the property name of a MemberExpression.
   * @param {ASTNode} memberExpressionNode The MemberExpression node.
   * @returns {string|undefined} Returns the property name if available, undefined else.
   */
  function getPropertyName(memberExpressionNode) {
      if (memberExpressionNode.computed) {
          if (memberExpressionNode.property.type === "Literal") {
              return memberExpressionNode.property.value;
          }
      } else {
          return memberExpressionNode.property.name;
      }
  }
  
  /**
   * Finds the escope reference in the given scope.
   * @param {Object} scope The scope to search.
   * @param {ASTNode} node The identifier node.
   * @returns {Reference|undefined} Returns the found reference or undefined if none were found.
   */
  function findReference(scope, node) {
      var references = scope.references.filter(function(reference) {
          return reference.identifier.range[0] === node.range[0] &&
              reference.identifier.range[1] === node.range[1];
      });
  
      if (references.length === 1) {
          return references[0];
      }
  }
  
  /**
   * Checks if the given identifier name is shadowed in the given global scope.
   * @param {Object} globalScope The global scope.
   * @param {string} identifierName The identifier name to check
   * @returns {boolean} Whether or not the name is shadowed globally.
   */
  function isGloballyShadowed(globalScope, identifierName) {
      var variable = globalScope.set.get(identifierName);
      return Boolean(variable && variable.defs.length > 0);
  }
  
  /**
   * Checks if the given identifier node is shadowed in the given scope.
   * @param {Object} scope The current scope.
   * @param {Object} globalScope The global scope.
   * @param {string} node The identifier node to check
   * @returns {boolean} Whether or not the name is shadowed.
   */
  function isShadowed(scope, globalScope, node) {
      var reference = findReference(scope, node),
          identifierName = node.name;
  
      if (reference) {
          if (reference.resolved || isGloballyShadowed(globalScope, identifierName)) {
              return true;
          }
      }
  
      return false;
  }
  
  /**
   * Checks if the given identifier node is a ThisExpression in the global scope or the global window property.
   * @param {Object} scope The current scope.
   * @param {Object} globalScope The global scope.
   * @param {string} node The identifier node to check
   * @returns {boolean} Whether or not the node is a reference to the global object.
   */
  function isGlobalThisReferenceOrGlobalWindow(scope, globalScope, node) {
      if (scope.type === "global" && node.type === "ThisExpression") {
          return true;
      } else if (node.name === "window") {
          return !isShadowed(scope, globalScope, node);
      }
  
      return false;
  }
  
  //------------------------------------------------------------------------------
  // Rule Definition
  //------------------------------------------------------------------------------
  
  module.exports = function(context) {
      var globalScope;
  
      return {
  
          "Program": function() {
              globalScope = context.getScope();
          },
  
          "CallExpression": function(node) {
              var callee = node.callee,
                  identifierName,
                  currentScope = context.getScope();
  
              // without window.
              if (callee.type === "Identifier") {
                  identifierName = callee.name;
  
                  if (!isShadowed(currentScope, globalScope, callee) && isProhibitedIdentifier(callee.name)) {
                      report(context, node, identifierName);
                  }
  
              } else if (callee.type === "MemberExpression" && isGlobalThisReferenceOrGlobalWindow(currentScope, globalScope, callee.object)) {
                  identifierName = getPropertyName(callee);
  
                  if (isProhibitedIdentifier(identifierName)) {
                      report(context, node, identifierName);
                  }
              }
  
          }
      };
  
  };
  
  module.exports.schema = [];