package com.hawhamburg.micr0bu

import com.hawhamburg.micr0bu.domain.asn1.ItsTime
import org.junit.Assert.assertEquals
import org.junit.Test

/**
 * Pins the arithmetic that moves a transmit timestamp from the phone's wall clock onto GNSS time.
 *
 * The cases come from the 2026-09-10 bench session. The sending phone's clock was 1456 s fast
 * because it had no automatic time source, and every CAM it sent was stamped 24 minutes in the
 * future. After a manual correction it was 6 s slow. Both have to come out on GNSS time.
 */
class ItsTimeTest {

    private val gnssNow = 1_789_038_922_000L

    @Test
    fun `without a GNSS reading the wall-clock time is used unchanged`() {
        assertEquals(1_000L, ItsTime.onGnssTime(systemMs = 1_000L, gnssNowMs = null, systemNowMs = 5_000L))
    }

    @Test
    fun `a phone clock running fast is pulled back onto GNSS time`() {
        val systemNow = gnssNow + 1_456_000L
        // A fix the wall clock stamped 0.8 s ago. It must still be 0.8 s old afterwards.
        val fix = systemNow - 800L
        assertEquals(gnssNow - 800L, ItsTime.onGnssTime(fix, gnssNow, systemNow))
    }

    @Test
    fun `a phone clock running slow is pushed forward onto GNSS time`() {
        val systemNow = gnssNow - 6_000L
        assertEquals(gnssNow - 250L, ItsTime.onGnssTime(systemNow - 250L, gnssNow, systemNow))
    }

    @Test
    fun `an accurate phone clock is left where it is`() {
        assertEquals(gnssNow - 40L, ItsTime.onGnssTime(gnssNow - 40L, gnssNow, gnssNow))
    }
}