(ns auto-ap.jobs.restore-from-backup
  (:require
   [amazonica.aws.s3 :as s3]
   [auto-ap.datomic :refer [transact-with-backoff]]
   [auto-ap.ledger]
   [auto-ap.jobs.core :refer [execute]]
   [clojure.edn :as edn]
   [clojure.java.io :as io]
   [clojure.set :as set]
   [com.brunobonacci.mulog :as mu]
   [config.core :refer [env]]
   [datomic.api :as dc]
   [lambdaisland.edn-lines :as ednl]
   [manifold.deferred :as de]
   [manifold.executor :as ex]
   [manifold.stream :as s]))

(def request-pool (ex/fixed-thread-executor 100))

(def buffered (ex/fixed-thread-executor 100))

(defn order-of-insert [entity-dependencies]
  (loop [entity-dependencies entity-dependencies
         order []]
    (let [next-order (for [[entity deps] entity-dependencies
                           :when         (not (seq deps))]
                       entity)
          next-deps (reduce
                     (fn [entity-dependencies next-entity]
                       (into {}
                             (map
                              (fn [[k v]]
                                [k (disj v next-entity)])
                              entity-dependencies)))
                     (apply dissoc entity-dependencies next-order)
                     next-order)]
      (if (seq next-deps)
        (recur next-deps (into order next-order))
        (into order next-order)))))

(def loaded (atom #{}))

(defn upsert-batch
  [batch context]
  (de/future-with request-pool
                  (mu/with-context context
                    (transact-with-backoff batch))
                  batch))

(defn pull-file [backup which]
  (mu/log ::pulling-file
          :file (str "/datomic-backup/" backup "/" which))
  (with-open [w (io/writer "/tmp/tmp-edn")]
    (io/copy (:input-stream (s3/get-object {:bucket-name "data.prod.app.integreatconsult.com"
                                            :key         (str "/datomic-backup/" backup "/" which)}))
             w))
  "/tmp/tmp-edn")

(def so-far (atom 0))
(def die? (atom false))

(defn load-entity [entity entities]
  (mu/trace ::restore-entity
            [:entity entity]
            (mu/with-context {:entity entity}
              (mu/log ::starting)
              @(s/consume (fn [batch]
                            (mu/with-context {:entity entity}
                              (try
                                (swap! so-far #(+ % (count batch)))
                                (mu/log ::loaded :count (count batch)
                                        :so-far @so-far)
                                (catch Exception e
                                  (mu/log ::error
                                          :exception e)
                                  (throw e)))))
                          (->> (partition-all 1000 entities)
                               (s/->source)
                               (s/onto buffered)
                               (s/map (fn [entities]
                                        (when @die?
                                          (reset! die? false)
                                          (throw (Exception. "dead")))
                                        (upsert-batch entities {:entity entity
                                                                :service "restore-from-backup"
                                                                :background-job "restore-from-backup"})))
                               (s/buffer 20)
                               (s/realize-each)))
              (swap! loaded conj entity))))

(defn load-from-backup
  ([backup-id connection] (load-from-backup backup-id connection nil))
  ([backup-id connection starting-at]
   (let [schema              (edn/read-string (slurp (pull-file backup-id "schema.edn")))
         full-dependencies   (edn/read-string (slurp (pull-file backup-id "full-dependencies.edn")))
         entity-dependencies (edn/read-string (slurp (pull-file backup-id "entity-dependencies.edn")))]
     @(dc/transact connection [{:db/ident       :entity/migration-key
                                :db/unique      :db.unique/identity
                                :db/cardinality :db.cardinality/one
                                :db/valueType   :db.type/long}])
     @(dc/transact connection (map
                               (fn [s]
                                 (set/rename-keys s {:db/id :entity/migration-key}))
                               schema))

     ;; TEMP - this has been fixed in current export (ezcater-olaciotn)
     @(dc/transact connection [{:entity/migration-key 17592257603901 :vendor/name "unknown"}
                               {:entity/migration-key 17592232621701}
                               {:entity/migration-key 17592263907739}
                               {:entity/migration-key 17592271516922}])

     (doseq [entity (cond->> (order-of-insert entity-dependencies)
                      true (filter #(not= "audit" %))
                      starting-at (drop-while #(not= starting-at %)))
             :let   [_ (reset! so-far 0)
                     _ (mu/log ::querying :entity entity)
                     entities (mu/trace ::file-pulled
                                        [:file (str backup-id "/" entity ".ednl")]
                                        (ednl/slurp (pull-file backup-id (str entity ".ednl"))))]]
       (load-entity entity entities)))))

(defn restore-fresh-from-backup [{:keys [backup starting-at]}]
  (println "beginning")
  (mu/log ::beginning-restore)
  (load-from-backup backup auto-ap.datomic/conn starting-at)
  (mu/log ::restore-complete)
  (mu/log ::beginning-index-build)
  (auto-ap.datomic/transact-schema auto-ap.datomic/conn)
  (mu/log ::index-build-complete)
  (mu/log ::refresh-running-balance-cache)
  #_(auto-ap.ledger/rebuild-running-balance-cache)
  (mu/log ::refresh-running-balance-cache-complete)
  (mu/log ::done))

(defn -main [& _]
  (try
    (println "restore")
    (execute "restore-from-backup" #(restore-fresh-from-backup (:args env)))
    (catch Exception e
      (println e)
      (mu/log ::quit-error
              :exception e
              :background-job "restore-from-backup"
              :service "restore-from-backup")
      (Thread/sleep 5000)
      (throw e))))

;; cloud load
#_(comment

  ;; /datomic-backup/079df203-eae0-4acf-94d5-8608ba8b8a9a
    (load-from-backup "079df203-eae0-4acf-94d5-8608ba8b8a9a" auto-ap.datomic/conn ["charge"])

    (load-entity "charge" (ednl/slurp "/tmp/tmp-edn")))

;; => nil