(ns clarktown.correctors.atx-heading-block
  (:require
    [clojure.string :as string]))


(defn empty-line-above?
  "Determines whether there's a need for an empty new line 
  above the `line` at the current `index`. In the case of a 
  ATX heading block that starts with the `#` character, if 
  there's no empty newline above, we need to create one, and 
  so this function must then return `true`."
  [lines line index]
  (and (string/starts-with? (string/trim line) "#")
       (> index 0)
       (not (= (-> (nth lines (- index 1))
                   string/trim) ""))))


(defn empty-line-below?
  "Determines whether there's a need for an empty new line
  below the `line` at the current `index`. In the case of a 
  ATX heading block that starts with the `#` character, if
  there's no empty newline below, we need to create one, and
  so this function must then return `true`."
  [lines line index]
  (and (string/starts-with? (string/trim line) "#")
       (< index (- (count lines) 1))
       (not (= (-> (nth lines (+ index 1))
                   string/trim) ""))))