/**
   * @fileoverview Rule to enforce declarations in program or function body root.
   * @author Brandon Mills
   * @copyright 2014 Brandon Mills. All rights reserved.
   */
  
  "use strict";
  
  //------------------------------------------------------------------------------
  // Rule Definition
  //------------------------------------------------------------------------------
  
  module.exports = function(context) {
  
      /**
       * Find the nearest Program or Function ancestor node.
       * @returns {Object} Ancestor's type and distance from node.
       */
      function nearestBody() {
          var ancestors = context.getAncestors(),
              ancestor = ancestors.pop(),
              generation = 1;
  
          while (ancestor && ["Program", "FunctionDeclaration",
                  "FunctionExpression", "ArrowFunctionExpression"
                  ].indexOf(ancestor.type) < 0) {
              generation += 1;
              ancestor = ancestors.pop();
          }
  
          return {
              // Type of containing ancestor
              type: ancestor.type,
              // Separation between ancestor and node
              distance: generation
          };
      }
  
      /**
       * Ensure that a given node is at a program or function body's root.
       * @param {ASTNode} node Declaration node to check.
       * @returns {void}
       */
      function check(node) {
          var body = nearestBody(node),
              valid = ((body.type === "Program" && body.distance === 1) ||
                  body.distance === 2);
  
          if (!valid) {
              context.report(node, "Move {{type}} declaration to {{body}} root.",
                  {
                      type: (node.type === "FunctionDeclaration" ?
                          "function" : "variable"),
                      body: (body.type === "Program" ?
                          "program" : "function body")
                  }
              );
          }
      }
  
      return {
  
          "FunctionDeclaration": check,
          "VariableDeclaration": function(node) {
              if (context.options[0] === "both" && node.kind === "var") {
                  check(node);
              }
          }
  
      };
  
  };
  
  module.exports.schema = [
      {
          "enum": ["functions", "both"]
      }
  ];