/**
   * @fileoverview A rule to choose between single and double quote marks
   * @author Matt DuVall <http://www.mattduvall.com/>, Brandon Payton
   * @copyright 2013 Matt DuVall. All rights reserved.
   * See LICENSE file in root directory for full license.
   */
  
  "use strict";
  
  //------------------------------------------------------------------------------
  // Requirements
  //------------------------------------------------------------------------------
  
  var astUtils = require("../ast-utils");
  
  //------------------------------------------------------------------------------
  // Constants
  //------------------------------------------------------------------------------
  
  var QUOTE_SETTINGS = {
      "double": {
          quote: "\"",
          alternateQuote: "'",
          description: "doublequote"
      },
      "single": {
          quote: "'",
          alternateQuote: "\"",
          description: "singlequote"
      },
      "backtick": {
          quote: "`",
          alternateQuote: "\"",
          description: "backtick"
      }
  };
  /**
   * Switches quoting of javascript string between ' " and `
   * escaping and unescaping as necessary.
   * Only escaping of the minimal set of characters is changed.
   * Note: escaping of newlines when switching from backtick to other quotes is not handled.
   * @param {string} str - A string to convert.
   * @returns {string} The string with changed quotes.
   * @private
   */
  QUOTE_SETTINGS.double.convert =
  QUOTE_SETTINGS.single.convert =
  QUOTE_SETTINGS.backtick.convert = function(str) {
      var newQuote = this.quote;
      var oldQuote = str[0];
      if (newQuote === oldQuote) {
          return str;
      }
      return newQuote + str.slice(1, -1).replace(/\\(\${|\r
  ?|
  |.)|["'`]|\${|(\r
  ?|
  )/g, function(match, escaped, newline) {
          if (escaped === oldQuote || oldQuote === "`" && escaped === "${") {
              return escaped; // unescape
          }
          if (match === newQuote || newQuote === "`" && match === "${") {
              return "\\" + match; // escape
          }
          if (newline && oldQuote === "`") {
              return "\
  "; // escape newlines
          }
          return match;
      }) + newQuote;
  };
  
  var AVOID_ESCAPE = "avoid-escape",
      FUNCTION_TYPE = /^(?:Arrow)?Function(?:Declaration|Expression)$/;
  
  //------------------------------------------------------------------------------
  // Rule Definition
  //------------------------------------------------------------------------------
  
  module.exports = function(context) {
      /**
       * Determines if a given node is part of JSX syntax.
       * @param {ASTNode} node The node to check.
       * @returns {boolean} True if the node is a JSX node, false if not.
       * @private
       */
      function isJSXElement(node) {
          return node.type.indexOf("JSX") === 0;
      }
  
      /**
       * Checks whether or not a given node is a directive.
       * The directive is a `ExpressionStatement` which has only a string literal.
       * @param {ASTNode} node - A node to check.
       * @returns {boolean} Whether or not the node is a directive.
       * @private
       */
      function isDirective(node) {
          return (
              node.type === "ExpressionStatement" &&
              node.expression.type === "Literal" &&
              typeof node.expression.value === "string"
          );
      }
  
      /**
       * Checks whether or not a given node is a part of directive prologues.
       * See also: http://www.ecma-international.org/ecma-262/6.0/#sec-directive-prologues-and-the-use-strict-directive
       * @param {ASTNode} node - A node to check.
       * @returns {boolean} Whether or not the node is a part of directive prologues.
       * @private
       */
      function isPartOfDirectivePrologue(node) {
          var block = node.parent.parent;
          if (block.type !== "Program" && (block.type !== "BlockStatement" || !FUNCTION_TYPE.test(block.parent.type))) {
              return false;
          }
  
          // Check the node is at a prologue.
          for (var i = 0; i < block.body.length; ++i) {
              var statement = block.body[i];
  
              if (statement === node.parent) {
                  return true;
              }
              if (!isDirective(statement)) {
                  break;
              }
          }
  
          return false;
      }
  
      /**
       * Checks whether or not a given node is allowed as non backtick.
       * @param {ASTNode} node - A node to check.
       * @returns {boolean} Whether or not the node is allowed as non backtick.
       * @private
       */
      function isAllowedAsNonBacktick(node) {
          var parent = node.parent;
  
          switch (parent.type) {
              // Directive Prologues.
              case "ExpressionStatement":
                  return isPartOfDirectivePrologue(node);
  
              // LiteralPropertyName.
              case "Property":
                  return parent.key === node && !parent.computed;
  
              // ModuleSpecifier.
              case "ImportDeclaration":
              case "ExportNamedDeclaration":
              case "ExportAllDeclaration":
                  return parent.source === node;
  
              // Others don't allow.
              default:
                  return false;
          }
      }
  
      return {
  
          "Literal": function(node) {
              var val = node.value,
                  rawVal = node.raw,
                  quoteOption = context.options[0],
                  settings = QUOTE_SETTINGS[quoteOption || "double"],
                  avoidEscape = context.options[1] === AVOID_ESCAPE,
                  isValid;
  
              if (settings && typeof val === "string") {
                  isValid = (quoteOption === "backtick" && isAllowedAsNonBacktick(node)) || isJSXElement(node.parent) || astUtils.isSurroundedBy(rawVal, settings.quote);
  
                  if (!isValid && avoidEscape) {
                      isValid = astUtils.isSurroundedBy(rawVal, settings.alternateQuote) && rawVal.indexOf(settings.quote) >= 0;
                  }
  
                  if (!isValid) {
                      context.report({
                          node: node,
                          message: "Strings must use " + settings.description + ".",
                          fix: function(fixer) {
                              return fixer.replaceText(node, settings.convert(node.raw));
                          }
                      });
                  }
              }
          }
      };
  
  };
  
  module.exports.schema = [
      {
          "enum": ["single", "double", "backtick"]
      },
      {
          "enum": ["avoid-escape"]
      }
  ];