MicrOBU/app/src/test/java/com/hawhamburg/micr0bu/StationLinkTest.kt

package com.hawhamburg.micr0bu

import com.hawhamburg.micr0bu.data.transport.BtpDataRequest
import com.hawhamburg.micr0bu.data.transport.LinkMessage
import com.hawhamburg.micr0bu.data.transport.LinkOpcode
import com.hawhamburg.micr0bu.data.transport.LinkResult
import com.hawhamburg.micr0bu.data.transport.LinkSecurityProfile
import com.hawhamburg.micr0bu.data.transport.PotiUpdate
import com.hawhamburg.micr0bu.data.transport.StationConfigure
import com.hawhamburg.micr0bu.data.transport.StationInfo
import com.hawhamburg.micr0bu.data.transport.StationStatus
import com.hawhamburg.micr0bu.data.transport.credentialsSegment
import org.junit.Assert.assertArrayEquals
import org.junit.Assert.assertEquals
import org.junit.Assert.assertNotNull
import org.junit.Assert.assertNull
import org.junit.Assert.assertTrue
import org.junit.Test

/**
 * Pins the phone side of the station-link message layer.
 *
 * ## Where the expected bytes come from
 * The colleague's Python implementation of the same protocol, microbu-esp32c5
 * station-link/python/microbu_link/messages.py (`encode_message` over each body's `encode`),
 * run with the same field values. That module is what their phone emulator drives the firmware
 * with, so an agreement here is agreement with a second, independent implementation.
 */
class StationLinkTest {

    private fun String.hexToBytes(): ByteArray = chunked(2).map { it.toInt(16).toByte() }.toByteArray()
    private fun ByteArray.hex(): String = joinToString("") { "%02x".format(it) }

    @Test
    fun `STATION_CONFIGURE matches the Python encoder`() {
        val body = StationConfigure(stationType = 2, mid = "021122334455".hexToBytes()).encode()
        assertEquals(
            "0100070002010002112233445500b40014020205",
            LinkMessage(LinkOpcode.STATION_CONFIGURE, 7, body).encode().hex(),
        )
    }

    @Test
    fun `POTI_UPDATE matches the Python encoder`() {
        val body = PotiUpdate(
            timestampMs = 717_254_800_123L, latTenMicroDeg = 535_546_667, lonTenMicroDeg = 100_223_889,
            semiMajorCm = 486, semiMinorCm = 486, speedCms = 543, headingDeciDeg = 1234, pai = true,
        ).encode()
        assertEquals(
            "02000800fbb2b7ffa60000002bcbeb1f914bf905e601e60100000e000000001f02d204",
            LinkMessage(LinkOpcode.POTI_UPDATE, 8, body).encode().hex(),
        )
    }

    @Test
    fun `BTP_DATA_REQUEST for a signed CAM matches the Python encoder`() {
        val body = BtpDataRequest(
            destinationPort = 2001, itsAid = 36, securityProfile = LinkSecurityProfile.SECURED,
            permissions = "010000".hexToBytes(), flSdu = "0102030405".hexToBytes(),
        ).encode()
        assertEquals(
            "0300090001d1070000010102ffff000000000024000000030100000005000102030405",
            LinkMessage(LinkOpcode.BTP_DATA_REQUEST, 9, body).encode().hex(),
        )
    }

    @Test
    fun `CREDENTIALS_PROVISION segment matches the Python encoder`() {
        val body = credentialsSegment(totalLength = 695, offset = 240, segment = ByteArray(3) { 0xAB.toByte() })
        assertEquals("04000a00b702f00003ababab", LinkMessage(LinkOpcode.CREDENTIALS_PROVISION, 10, body).encode().hex())
    }

    @Test
    fun `STATUS from the Python encoder decodes field by field`() {
        val message = LinkMessage.decode(
            ("8400341240e20100010800021122334455b80b49387a4c12eb00010b0000000c0000000d0000000e000000" +
                "0f000000100000001100000012000000130000001400000015000000160000001700000018000000" +
                "190000001a0000001b0000001c000000fbb2b7ffa6000000").hexToBytes(),
        )
        assertNotNull(message)
        assertEquals(LinkOpcode.STATUS, message!!.opcode)
        assertEquals(0x1234, message.sequence)
        val status = StationStatus.decode(message.body)!!
        assertEquals(123_456L, status.uptimeMs)
        assertTrue(status.configured)
        assertArrayEquals("b80b49387a4c12eb".hexToBytes(), status.identifier)
        assertEquals(1, status.tickets)
        assertEquals(11L, status.signedMessages)
        assertEquals(12L, status.refusedNoTicket)
        assertEquals(13L, status.refusedChangePending)
        assertEquals(14L, status.refusedPermission)
        assertEquals(15L, status.signFailed)
        assertEquals(16L, status.verified)
        assertEquals(17L, status.rejected)
        assertEquals(18L, status.requestsAccepted)
        assertEquals(19L, status.requestsRefused)
        assertEquals(21L, status.radioSubmitted)
        assertEquals(22L, status.radioFailed)
        assertEquals(23L, status.radioReceived)
        assertEquals(24L, status.radioDropped)
        assertEquals(26L, status.linkCrcErrors)
        assertEquals(27L, status.linkMalformed)
        assertEquals(28L, status.potiUpdates)
        assertEquals(717_254_800_123L, status.itsTimeMs)
    }

    @Test
    fun `a STATUS of the wrong length is refused, as the Python decoder does`() {
        assertNull(StationStatus.decode(ByteArray(StationStatus.SIZE + 1)))
    }

    @Test
    fun `RESULT of STATION_CONFIGURE carries the credential state`() {
        val message = LinkMessage.decode("8000070000120800021122334455b80b49387a4c12eb0101".hexToBytes())!!
        val result = LinkResult.decode(message.body)!!
        assertTrue(result.accepted)
        assertEquals(StationInfo(credentialsLoaded = true, tickets = 1), StationInfo.decode(result.detail))
    }
}