package pw.binom.llmproxy

import kotlinx.coroutines.test.runTest
import kotlinx.datetime.Instant
import kotlin.test.Test
import kotlin.test.assertEquals
import kotlin.test.assertFails
import kotlin.test.assertFalse
import kotlin.test.assertNull
import kotlin.test.assertTrue
import kotlin.time.Duration
import kotlin.time.Duration.Companion.days
import kotlin.time.Duration.Companion.hours
import kotlin.time.Duration.Companion.milliseconds
import kotlin.time.Duration.Companion.minutes
import kotlin.time.Duration.Companion.seconds

class BackoffTest {

    private val t0 = Instant.fromEpochSeconds(1_700_000_000)

    @Test
    fun intervalsDoubleUntilCap() = runTest {
        val g = BackoffGuard(cap = 30.seconds)
        val seq = (1..7).map { g.recordFailure(t0) }
        assertEquals(
            listOf(1.seconds, 2.seconds, 4.seconds, 8.seconds, 16.seconds, 30.seconds, 30.seconds),
            seq,
        )
    }

    @Test
    fun successResetsCounter() = runTest {
        val g = BackoffGuard(cap = 30.seconds)
        g.recordFailure(t0)
        g.recordFailure(t0)
        g.recordSuccess()
        assertEquals(1.seconds, g.recordFailure(t0))
        assertFalse(g.isCoolingAt(t0 + 1.days))
    }

    @Test
    fun coolingWindow() = runTest {
        val g = BackoffGuard(cap = 30.seconds)
        g.recordFailure(t0) // отдых 1s
        assertTrue(g.isCoolingAt(t0 + 500.milliseconds))
        assertFalse(g.isCoolingAt(t0 + 1.seconds))
        assertEquals(500.milliseconds, g.remainingAt(t0 + 500.milliseconds))
    }

    @Test
    fun iso8601CapParsing() {
        assertEquals(30.minutes, Duration.parse("PT30M"))
        assertEquals(1.days, Duration.parse("P1D"))
        assertEquals(90.seconds, Duration.parse("PT1M30S"))
    }

    @Test
    fun configDurationParsingWithYearsAndMonths() {
        // kotlin.time не принимает Y/M — конфиг-парсер расширяет: 1Y≈365d, 1M≈30d
        assertEquals(30.days, parseIsoDuration("P1M"))
        assertEquals(365.days, parseIsoDuration("P1Y"))
        assertEquals(455.days, parseIsoDuration("P1Y3M"))
        assertEquals(7.days, parseIsoDuration("P1W"))
        assertEquals(2.days + 3.hours + 15.minutes, parseIsoDuration("P2DT3H15M"))
        // базовый ISO-8601 без Y/M — как kotlin.time
        assertEquals(30.minutes, parseIsoDuration("PT30M"))
    }

    @Test
    fun configDurationParsingRejectsGarbage() {
        assertFails { parseIsoDuration("PT30") }
        assertFails { parseIsoDuration("1d") }
        assertFails { parseIsoDuration("P") }
        assertFails { parseIsoDuration("") }
    }

    @Test
    fun providerScopeSharedBetweenItsModels() = runTest {
        val p = ProviderConf(id = "p", url = "https://p", backoff = 5.minutes)
        val a = UpstreamConf(id = "a", provider = "p", model = "m1")
        val b = UpstreamConf(id = "b", provider = "p", model = "m2")
        val reg = BackoffRegistry(mapOf("p" to p), mapOf("a" to a, "b" to b))

        assertEquals(1.seconds, reg.recordFailure(a))

        // общая скоуп-переменная провайдера: сбой на a охладил и b
        assertTrue(reg.isCooling(a))
        assertTrue(reg.isCooling(b))
    }

    @Test
    fun upstreamBackoffOverridesProvider() = runTest {
        val p = ProviderConf(id = "p", url = "https://p", backoff = 5.minutes)
        val a = UpstreamConf(id = "a", provider = "p", model = "m1")
        val b = UpstreamConf(id = "b", provider = "p", model = "m2", backoff = 30.seconds)
        val reg = BackoffRegistry(mapOf("p" to p), mapOf("a" to a, "b" to b))

        // своё backoff у b: cap 30s (не 5m провайдера): 1s, 2s, 4s, 8s, 16s, 30s (потолок)
        val seq = (1..6).map { reg.recordFailure(b) }
        assertEquals(listOf(1.seconds, 2.seconds, 4.seconds, 8.seconds, 16.seconds, 30.seconds), seq)
        // скоупы независимы: сбои b не охлаждают a (провайдерский скоуп)
        assertFalse(reg.isCooling(a))
        assertTrue(reg.isCooling(b))
    }

    @Test
    fun providerFailureDoesNotCoolUpstreamWithOwnBackoff() = runTest {
        val p = ProviderConf(id = "p", url = "https://p", backoff = 5.minutes)
        val a = UpstreamConf(id = "a", provider = "p", model = "m1")
        val b = UpstreamConf(id = "b", provider = "p", model = "m2", backoff = 30.minutes)
        val reg = BackoffRegistry(mapOf("p" to p), mapOf("a" to a, "b" to b))

        // провайдерский скоуп заведён сбоем на a:
        reg.recordFailure(a)
        assertTrue(reg.isCooling(a))
        // b живёт своим (provider-scope на него не действует):
        assertFalse(reg.isCooling(b))
    }

    @Test
    fun noBackoffConfiguredMeansNoCooling() = runTest {
        val p = ProviderConf(id = "p", url = "https://p")
        val a = UpstreamConf(id = "a", provider = "p", model = "m1")
        val reg = BackoffRegistry(mapOf("p" to p), mapOf("a" to a))

        assertNull(reg.recordFailure(a))
        assertFalse(reg.isCooling(a))
        assertEquals(0L, reg.remainingSeconds(a))
    }
}