(ns pocketbook.core-test
  (:require [clojure.test :refer [deftest is testing use-fixtures]]
            [promesa.core :as p]
            [pocketbook.core :as pb]
            [pocketbook.store :as store]
            [pocketbook.store.memory :as memory]
            [pocketbook.server :as server])
  (:import [java.io File]))

;; ---------------------------------------------------------------------------
;; Fixtures — start a real server for sync tests
;; ---------------------------------------------------------------------------

(def ^:dynamic *port* nil)
(def ^:dynamic *server* nil)

(defn- free-port []
  (with-open [s (java.net.ServerSocket. 0)]
    (.getLocalPort s)))

(use-fixtures :each
  (fn [f]
    (let [port    (free-port)
          db-path (str (File/createTempFile "pocketbook-core-test" ".db"))
          srv     (server/start! {:port port :db-path db-path})]
      (Thread/sleep 200)
      (try
        (binding [*server* srv *port* port]
          (f))
        (finally
          (server/stop! srv)
          (.delete (File. db-path)))))))

(defn- server-url []
  (str "http://localhost:" *port* "/sync"))

;; ---------------------------------------------------------------------------
;; Helpers
;; ---------------------------------------------------------------------------

(defn- await!
  "Deref a promise with timeout. Returns nil on timeout."
  [promise ms]
  (deref promise ms nil))

(defn- wait-synced
  "Wait until the synced atom has no pending changes."
  [sa ms]
  (let [deadline (+ (System/currentTimeMillis) ms)]
    (loop []
      (when (and (pos? (pb/pending-count sa))
                 (< (System/currentTimeMillis) deadline))
        (Thread/sleep 50)
        (recur)))))

;; ---------------------------------------------------------------------------
;; Tests
;; ---------------------------------------------------------------------------

(deftest synced-atom-local-only
  (testing "SyncedAtom works without a server (local store only)"
    (let [store (memory/create)
          sa    (pb/synced-atom store "todo")]
      (await! (pb/ready? sa) 1000)
      (is (= {} @sa))

      (swap! sa assoc "todo:1" {:text "Buy milk"})
      (is (= {:text "Buy milk"} (get @sa "todo:1")))

      (swap! sa assoc "todo:2" {:text "Walk dog"})
      (is (= 2 (count @sa)))

      (swap! sa dissoc "todo:1")
      (is (= 1 (count @sa)))
      (is (nil? (get @sa "todo:1")))

      (pb/destroy! sa))))

(deftest synced-atom-persists-to-store
  (testing "Changes are persisted to the store"
    (let [store (memory/create)
          sa    (pb/synced-atom store "todo")]
      (await! (pb/ready? sa) 1000)

      (swap! sa assoc "todo:1" {:text "Buy milk"})
      (Thread/sleep 50) ;; let async store write complete

      ;; Read from store directly
      (let [docs (await! (store/docs-by-prefix store "todo:") 1000)]
        (is (= 1 (count docs)))
        (is (= "todo:1" (:id (first docs))))
        (is (= {:text "Buy milk"} (:value (first docs)))))

      (pb/destroy! sa))))

(deftest synced-atom-loads-from-store
  (testing "SyncedAtom loads existing data from store on creation"
    (let [store (memory/create)]
      ;; Pre-populate the store
      (await! (store/put-doc! store
                {:id "todo:1" :value {:text "Existing"}
                 :version 1 :updated 1000 :deleted false :synced true})
              1000)

      (let [sa (pb/synced-atom store "todo")]
        (await! (pb/ready? sa) 1000)
        (is (= {:text "Existing"} (get @sa "todo:1")))
        (pb/destroy! sa)))))

(deftest synced-atom-watches
  (testing "add-watch fires on changes"
    (let [store   (memory/create)
          sa      (pb/synced-atom store "todo")
          changes (atom [])]
      (await! (pb/ready? sa) 1000)

      (add-watch sa :test (fn [_ _ old new]
                            (swap! changes conj {:old old :new new})))

      (swap! sa assoc "todo:1" {:text "Hello"})
      (Thread/sleep 50)

      (is (= 1 (count @changes)))
      (is (= {} (:old (first @changes))))
      (is (= {"todo:1" {:text "Hello"}} (:new (first @changes))))

      (remove-watch sa :test)
      (pb/destroy! sa))))

(deftest synced-atom-push-to-server
  (testing "Local changes are pushed to the server"
    (let [store (memory/create)
          sa    (pb/synced-atom store "todo"
                  {:server (server-url)})]
      (await! (pb/ready? sa) 2000)

      (swap! sa assoc "todo:push1" {:text "Pushed!"})
      (Thread/sleep 500) ;; let push complete

      (is (zero? (pb/pending-count sa)))
      (pb/destroy! sa))))

(deftest synced-atom-pull-from-server
  (testing "Two clients sync via server"
    (let [store-a (memory/create)
          store-b (memory/create)
          sa-a    (pb/synced-atom store-a "todo"
                    {:server (server-url) :interval 500})
          sa-b    (pb/synced-atom store-b "todo"
                    {:server (server-url) :interval 500})]
      (await! (pb/ready? sa-a) 2000)
      (await! (pb/ready? sa-b) 2000)

      ;; Client A writes
      (swap! sa-a assoc "todo:sync1" {:text "From A"})
      (Thread/sleep 500) ;; let A push

      ;; Trigger a sync on B
      (await! (pb/sync-now! sa-b) 2000)

      ;; B should have A's data
      (is (= {:text "From A"} (get @sa-b "todo:sync1")))

      (pb/destroy! sa-a)
      (pb/destroy! sa-b))))

(deftest synced-atom-deref-swap-reset
  (testing "Standard atom operations work"
    (let [store (memory/create)
          sa    (pb/synced-atom store "note")]
      (await! (pb/ready? sa) 1000)

      ;; reset!
      (reset! sa {"note:1" {:body "Hello"}})
      (is (= {"note:1" {:body "Hello"}} @sa))

      ;; swap! with multiple args
      (swap! sa assoc "note:2" {:body "World"})
      (is (= 2 (count @sa)))

      (swap! sa update "note:1" assoc :edited true)
      (is (true? (:edited (get @sa "note:1"))))

      (pb/destroy! sa))))