add timers repo and timers handler

triggers/timer/src/commonMain/kotlin/TimersHandler.kt

@@ -0,0 +1,57 @@
+package dev.inmo.plaguposter.triggers.timer
+
+import com.soywiz.klock.DateTime
+import dev.inmo.micro_utils.coroutines.launchSafelyWithoutExceptions
+import dev.inmo.micro_utils.coroutines.plus
+import dev.inmo.micro_utils.coroutines.subscribeSafelyWithoutExceptions
+import dev.inmo.micro_utils.repos.unset
+import dev.inmo.plaguposter.posts.models.PostId
+import dev.inmo.plaguposter.posts.sending.PostPublisher
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.flow.flowOf
+import kotlinx.coroutines.sync.Mutex
+import kotlinx.coroutines.sync.withLock
+
+class TimersHandler(
+    private val timersRepo: TimersRepo,
+    private val publisher: PostPublisher,
+    private val scope: CoroutineScope
+) {
+    private var currentPostAndJob: Pair<PostId, Job>? = null
+    private val currentJobMutex = Mutex()
+
+    init {
+        (flowOf(Unit) + timersRepo.onNewValue + timersRepo.onValueRemoved).subscribeSafelyWithoutExceptions(scope) {
+            refreshPublishingJob()
+        }
+    }
+
+    private suspend fun refreshPublishingJob() {
+        val minimal = timersRepo.getMinimalDateTimePost()
+
+        currentJobMutex.withLock {
+            if (minimal ?.first == currentPostAndJob ?.first) {
+                return@withLock
+            }
+
+            currentPostAndJob ?.second ?.cancel()
+
+            currentPostAndJob = minimal ?.let { (postId, dateTime) ->
+                postId to scope.launchSafelyWithoutExceptions {
+                    val now = DateTime.now()
+                    val span = dateTime - now
+
+                    delay(span.millisecondsLong)
+
+                    publisher.publish(postId)
+
+                    timersRepo.unset(postId)
+
+                    refreshPublishingJob()
+                }
+            }
+        }
+    }
+}