replication.Storing.scala Maven / Gradle / Ivy

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replication

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package replication

import com.github.plokhotnyuk.jsoniter_scala.core.*
import org.scalajs.dom
import reactives.default.Signal

object Storing {

  def initializedOnce[A: JsonValueCodec](key: String, default: => A): A = {
    val item: String | Null = dom.window.localStorage.getItem(key)
    if item == null then default
    else {
      val res =
        try {
          readFromString[A](item)
        } catch {
          case cause: Throwable =>
            println(s"could not restore $key: $cause")
            cause.printStackTrace()
            dom.window.localStorage.removeItem(key)
            default
        }
      println(s"restored $res")
      res
    }
  }

  def storedAs[A: JsonValueCodec](key: String, default: => A)(create: A => Signal[A]): Signal[A] = {

    val init = initializedOnce(key, default)
    val sig  = create(init)
    sig.observe(
      { (ft: A) =>
        println(s"storing $key")
        dom.window.localStorage.setItem(key, writeToString(ft))
      },
      fireImmediately = true
    )
    sig
  }

}