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

package com.hawhamburg.micr0bu

import com.hawhamburg.micr0bu.domain.denm.DenmParser
import org.junit.Assert.assertEquals
import org.junit.Assert.assertFalse
import org.junit.Assert.assertNotNull
import org.junit.Assert.assertNull
import org.junit.Assert.assertTrue
import org.junit.Test

/**
 * Tests [DenmParser] against the CiT One Use Case API's documented DENM schema.
 *
 * The payload below is the worked example from `CI-CiT-MQTT_API_Documentation-v6-20250221.pdf`,
 * listing 2.6 (section 2.2.4, "Processed DENM"), reproduced field-for-field. That document is the
 * contract for this topic, so it is the right thing to pin against - the previous parser was
 * written before the schema was checked and silently dropped every real DENM for two independent
 * reasons: the station id is `originatingStationId` (not `stationId`), and `eventPosition` is
 * itself a GeoJSON Point rather than an object containing one.
 */
class DenmParserMqttTest {

    /** Listing 2.6 from the API documentation, with the doc's inline comments removed. */
    private val documentedDenm = """
        {
          "type": "v2x-denm",
          "originatingStationId": 1345267,
          "sequenceNumber": 1,
          "detectionTime": "2021-05-11T12:01:02+00:00",
          "referenceTime": "2021-05-11T12:01:02+00:00",
          "eventPosition": { "type": "Point", "coordinates": [9.9800230, 53.5560783, 15] },
          "relevanceTrafficDirection": "upstreamTraffic",
          "stationType": "roadSideUnit",
          "causeCode": "trafficCondition",
          "subCauseCode": 0
        }
    """.trimIndent()

    @Test
    fun `parses the documented DENM payload`() {
        val denm = DenmParser.parse(documentedDenm, timestamp = 1_787_000_000_000L)
        assertNotNull("the API's own documented payload must parse", denm)
        denm!!

        assertEquals(1_345_267L, denm.stationId)
        assertEquals(1, denm.sequenceNumber)

        // GeoJSON is [longitude, latitude, altitude] - getting this order wrong puts a Hamburg
        // hazard in Somalia, and both values are plausible-looking numbers either way.
        assertEquals(53.5560783, denm.latitude, 1e-7)
        assertEquals(9.9800230, denm.longitude, 1e-7)

        assertEquals(1, denm.causeCode)      // trafficCondition
        assertEquals(0, denm.subCauseCode)
        assertEquals(15, denm.stationType)   // roadSideUnit is 15, not 12 - the enum has a gap
        assertFalse(denm.isTermination)

        // 2021-05-11T12:01:02Z
        assertEquals(1_620_734_462_000L, denm.detectionTimeMs)
    }

    @Test
    fun `termination is signalled by the key being present`() {
        val terminated = documentedDenm.replace(
            "\"sequenceNumber\": 1,",
            "\"sequenceNumber\": 1,\n  \"termination\": true,",
        )
        val denm = DenmParser.parse(terminated)
        assertNotNull(denm)
        assertTrue(denm!!.isTermination)
    }

    @Test
    fun `a termination shares the dedup key of the event it ends`() {
        val active = DenmParser.parse(documentedDenm)!!
        val terminated = DenmParser.parse(
            documentedDenm.replace(
                "\"sequenceNumber\": 1,",
                "\"sequenceNumber\": 1,\n  \"termination\": true,",
            )
        )!!
        // Without this, a cancelled hazard would be filtered out while the active pin it was
        // meant to cancel stayed on the map forever.
        assertEquals(active.dedupKey, terminated.dedupKey)
    }

    @Test
    fun `cause code names follow the ETSI spelling the API uses`() {
        // ETSI's CauseCodeType really does spell it with three n's, and the API follows.
        val aqua = documentedDenm.replace("\"trafficCondition\"", "\"aquaplannning\"")
        assertEquals(7, DenmParser.parse(aqua)!!.causeCode)

        val stationary = documentedDenm.replace("\"trafficCondition\"", "\"stationaryVehicle\"")
        assertEquals(94, DenmParser.parse(stationary)!!.causeCode)
    }

    @Test
    fun `a payload with no usable position is rejected rather than placed at null island`() {
        val noPosition = documentedDenm.replace(
            "\"eventPosition\": { \"type\": \"Point\", \"coordinates\": [9.9800230, 53.5560783, 15] },",
            "",
        )
        assertNull(DenmParser.parse(noPosition))
    }

    @Test
    fun `integer causeCode and stationId spellings still parse`() {
        // The air path and any future firmware-side JSON produce integers; those must keep working.
        val numeric = """
            {"stationId": 42, "causeCode": 94, "subCauseCode": 1,
             "eventPosition": {"type": "Point", "coordinates": [10.0, 53.5]}}
        """.trimIndent()
        val denm = DenmParser.parse(numeric)
        assertNotNull(denm)
        assertEquals(42L, denm!!.stationId)
        assertEquals(94, denm.causeCode)
        assertEquals(1, denm.subCauseCode)
    }
}