(ns java-time.adjuster

(:require [java-time.util :as jt.u]

[java-time.single-field :as jt.sf])

(:import [java.time.temporal Temporal TemporalAdjusters TemporalAdjuster]))

(def base-adjusters {:first-day-of-month [(TemporalAdjusters/firstDayOfMonth) 0]

:last-day-of-month [(TemporalAdjusters/lastDayOfMonth) 0]

:first-day-of-next-month [(TemporalAdjusters/firstDayOfNextMonth) 0]

:first-day-of-year [(TemporalAdjusters/firstDayOfYear) 0]

:last-day-of-year [(TemporalAdjusters/lastDayOfYear) 0]

:first-day-of-next-year [(TemporalAdjusters/firstDayOfNextYear) 0]

:first-in-month [#(TemporalAdjusters/firstInMonth (jt.sf/day-of-week %)) 1]

:last-in-month [#(TemporalAdjusters/lastInMonth (jt.sf/day-of-week %)) 1]

:day-of-week-in-month [#(TemporalAdjusters/dayOfWeekInMonth

(int %1) (jt.sf/day-of-week %2)) 2]

:next-day-of-week [#(TemporalAdjusters/next (jt.sf/day-of-week %)) 1]

:next-or-same-day-of-week [#(TemporalAdjusters/nextOrSame (jt.sf/day-of-week %)) 1]

:previous-day-of-week [#(TemporalAdjusters/previous (jt.sf/day-of-week %)) 1]

:previous-or-same-day-of-week [#(TemporalAdjusters/previousOrSame (jt.sf/day-of-week %)) 1]})

(def extra-adjusters

(jt.u/if-threeten-extra

{:next-working-day [(org.threeten.extra.Temporals/nextWorkingDay) 0]

:previous-working-day [(org.threeten.extra.Temporals/previousWorkingDay) 0]}

{}))

(def predefined-adjusters (merge base-adjusters extra-adjusters))

(defn- ^TemporalAdjuster get-adjuster [kw args]

(if-let [[adj nargs] (get predefined-adjusters kw)]

(if (zero? nargs)

adj

(if (= (count args) nargs)

(apply adj args)

(throw (java.time.DateTimeException.

(str "Adjuster: " (name kw) " cannot be created from" args "!")))))

(throw (java.time.DateTimeException.

(str "Adjuster: " (name kw) " not found!")))))

(defn adjust

"Adjusts the temporal `entity` using the provided `adjuster` with optional `args`.

[entity adjuster & args]

(cond (instance? TemporalAdjuster adjuster)

(.adjustInto ^TemporalAdjuster adjuster ^Temporal entity)

(fn? adjuster)

(apply adjuster entity args)

(keyword? adjuster)

(.adjustInto (get-adjuster adjuster args) ^Temporal entity)))