/**
   * @fileoverview Rule to disallow if as the only statmenet in an else block
   * @author Brandon Mills
   */
  "use strict";
  
  //------------------------------------------------------------------------------
  // Rule Definition
  //------------------------------------------------------------------------------
  
  module.exports = {
      meta: {
          docs: {
              description: "disallow `if` statements as the only statement in `else` blocks",
              category: "Stylistic Issues",
              recommended: false
          },
  
          schema: [],
  
          fixable: "code"
      },
  
      create(context) {
          const sourceCode = context.getSourceCode();
  
          return {
              IfStatement(node) {
                  const ancestors = context.getAncestors(),
                      parent = ancestors.pop(),
                      grandparent = ancestors.pop();
  
                  if (parent && parent.type === "BlockStatement" &&
                          parent.body.length === 1 && grandparent &&
                          grandparent.type === "IfStatement" &&
                          parent === grandparent.alternate) {
                      context.report({
                          node,
                          message: "Unexpected if as the only statement in an else block.",
                          fix(fixer) {
                              const openingElseCurly = sourceCode.getFirstToken(parent);
                              const closingElseCurly = sourceCode.getLastToken(parent);
                              const elseKeyword = sourceCode.getTokenBefore(openingElseCurly);
                              const tokenAfterElseBlock = sourceCode.getTokenAfter(closingElseCurly);
                              const lastIfToken = sourceCode.getLastToken(node.consequent);
                              const sourceText = sourceCode.getText();
  
                              if (sourceText.slice(openingElseCurly.range[1], node.range[0]).trim() || sourceText.slice(node.range[1], closingElseCurly.range[0]).trim()) {
  
                                  // Don't fix if there are any non-whitespace characters interfering (e.g. comments)
                                  return null;
                              }
  
                              if (
                                  node.consequent.type !== "BlockStatement" && lastIfToken.value !== ";" && tokenAfterElseBlock &&
                                  (
                                      node.consequent.loc.end.line === tokenAfterElseBlock.loc.start.line ||
                                      /^[([/+`-]/.test(tokenAfterElseBlock.value) ||
                                      lastIfToken.value === "++" ||
                                      lastIfToken.value === "--"
                                  )
                              ) {
  
                                  /*
                                   * If the `if` statement has no block, and is not followed by a semicolon, make sure that fixing
                                   * the issue would not change semantics due to ASI. If this would happen, don't do a fix.
                                   */
                                  return null;
                              }
  
                              return fixer.replaceTextRange(
                                  [openingElseCurly.range[0], closingElseCurly.range[1]],
                                  (elseKeyword.range[1] === openingElseCurly.range[0] ? " " : "") + sourceCode.getText(node)
                              );
                          }
                      });
                  }
              }
          };
  
      }
  };