package gs.test.v0

import cats.effect.IO
import cats.effect.unsafe.IORuntime
import gs.timing.v0.ElapsedTime
import gs.timing.v0.Timing
import java.util.concurrent.TimeUnit
import munit.*
import scala.concurrent.duration.FiniteDuration

class TimingTests extends FunSuite:

  given IORuntime = IORuntime.global

  iotest("should retrieve monotonic time") {
    for
      (provider, timing) <- Timing.manual[IO]
      t1                 <- timing.monotonic()
      t2                 <- timing.monotonic()
      _                  <- provider.tick()
      t3                 <- timing.monotonic()
      _                  <- provider.tick()
      t4                 <- timing.monotonic()
      _                  <- provider.reset()
      t5                 <- timing.monotonic()
    yield
      assertEquals(t1, 0L)
      assertEquals(t2, 0L)
      assertEquals(t3, 1L)
      assertEquals(t4, 2L)
      assertEquals(t5, 0L)
  }

  iotest("should create a timer based on the current provider") {
    val start   = 0L
    val end     = 1000000L * 2000L // 2 seconds, 2000 millis
    val nanos   = end - start
    val millis  = nanos / 1000000L
    val seconds = millis / 1000L

    for
      (provider, timing) <- Timing.manual[IO]
      timer              <- timing.start()
      e1                 <- timer.checkpoint()
      _                  <- provider.set(end)
      e2                 <- timer.checkpoint()
    yield
      assertEquals(
        e1,
        ElapsedTime(start, 0L, FiniteDuration(0L, TimeUnit.NANOSECONDS))
      )
      assertEquals(
        e2,
        ElapsedTime(start, end, FiniteDuration(nanos, TimeUnit.NANOSECONDS))
      )
      assertEquals(e2.toMilliseconds(), millis)
      assertEquals(e2.toSeconds(), seconds)
  }

  iotest("should capture system time") {
    for
      timing <- IO(Timing.system[IO])
      t1     <- timing.monotonic()
      _      <- IO.sleep(FiniteDuration(1L, TimeUnit.MILLISECONDS))
      t2     <- timing.monotonic()
    yield assert(
      t2 > t1,
      "The system clock should detect that at least 1 nanosecond has passed after sleeping for 1 millisecond."
    )
  }

  private def iotest(
    name: String
  )(
    body: => IO[Any]
  )(
    implicit
    loc: Location
  ): Unit =
    test(name)(body.unsafeRunSync())