pag_first_map.clj

(ns com.github.ivarref.clj-paginate.impl.pag-first-map
  (:require [com.github.ivarref.clj-paginate.impl.bst2 :as bst2]
            [com.github.ivarref.clj-paginate.impl.utils :as u]))

(defn paginate-first [m
                      {:keys [max-items
                              f
                              batch-f
                              sort-attrs
                              context
                              filter
                              sort-fn]
                       :or   {f       identity
                              batch-f identity
                              context nil}}
                      cursor-str]
  (let [vecs (into [] (vals m))
        decoded-cursor (u/maybe-decode-cursor cursor-str)
        cursor (-> (merge {:context context}
                          (when filter {:filter filter})
                          decoded-cursor))
        sort-fn (if sort-fn sort-fn (apply juxt sort-attrs))
        nodes-plus-1 (if-let [from-value (get cursor :cursor)]
                       (do
                         (when (not= (count from-value) (count sort-attrs))
                           (throw (ex-info "Mismatch in size of :node-id-attrs and :cursor" {:node-id-attrs sort-attrs
                                                                                             :cursor from-value})))
                         (bst2/after-value2 vecs (zipmap sort-attrs from-value) sort-fn (inc max-items)))
                       (bst2/from-beginning vecs sort-fn (inc max-items)))
        edges (u/get-edges (take max-items nodes-plus-1) batch-f f sort-attrs cursor)
        hasPrevPage (or (when (not-empty nodes-plus-1)
                          (not= (first nodes-plus-1)
                                (first (bst2/from-beginning vecs sort-fn 1))))
                        (and (empty? nodes-plus-1)
                             (some? cursor-str)))]
    {:edges    edges
     :pageInfo {:hasPrevPage (true? hasPrevPage)
                :hasNextPage (= (count nodes-plus-1) (inc max-items))
                :startCursor (or (get (first edges) :cursor) cursor-str)
                :endCursor   (or (get (last edges) :cursor) cursor-str)
                :totalCount  (bst2/total-count vecs)}}))