data class TimelinePoint (
    val name: String,
    val time: TimezonedDatetime,
    val address: Address
)

data class TripItem<TMetadata : TripItemMetadata> { // with this structure we can use RDS
    val id: UUID,
    val note: String,
    val attachments: List<DocumentLink>,
    val metadata: TMetadata // since we use it only to generate timeline (only once) and showing in the UI - it could be stored in JSON column.
                         // Use it as a joined table would be problematic since there're different types of metadata
} {
    val timelinePoints: TimeInterval // even so it generated, does it make sense to store it in the DB in a dedicated column?
        get = metadata.getTimelinePoints()
}

data class TimeInterval (
    val start: TimelinePoint,
    val end: TimelinePoint
)

interface TripItemMetadata {
    fun getTimelinePoints(): TimeInterval
}

data class Flight : TripItemMetadata (
    val flightNumber: String,
    val carrier: String,
    val bookingCode: String,
    val seat: String,
    val passengers: List<Person>,
    val departure: AirportPoint,
    val arrival: AirportPoint
) {
    fun getTimelinePoints(): TimeInterval =
        TimeInterval(
           TimelinePoint(
               "Flight [${departure.airport.code}]",
               departure.time,
               departure.airport.address
           ),
           TimelinePoint(
               "Flight [${arrival.airport.code}]",
               arrival.time,
               arrival.airport.address
           )
       )
}

// ...

val flight = TripItem<Flight>(
    UUID.generateId(),
    "Sample note",
    emptyList(),
    Flight(...)
)

val tlPoints = flight.timelinePoints

interface TripItem { 
    val id: UUID,
    val note: String, 
    val attachments: List<DocumentLink>,
    val timelinePoints: List<TimelinePoint>,

    val isObservingEvent: Bool
}

data class TripItem<TMetadata : TripItemMetadata> { 
    val id: UUID,
    val note: String,
    val attachments: List<DocumentLink>,
    val metadata: TMetadata,

    val isObservingEvent: Bool
}

data class Timeline( // Should be a property for a `TripItem` instead of "ObeservationEvent" flag.
    val id: String,
    val name: String,
    val blockColor: Color, // or Enum or HEX string
    val backgroundColor: Color,
    val order: Int // For example, "Major transfers" is "1", and "Friend 2 - Transfers" is "4"
)