Meshtastic-Android/app/src/main/java/com/geeksville/mesh/DataPacket.kt

/*
 * Copyright (c) 2025 Meshtastic LLC
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

package com.geeksville.mesh

import android.os.Parcel
import android.os.Parcelable
import kotlinx.parcelize.Parcelize
import kotlinx.serialization.Serializable

/**
 * Generic [Parcel.readParcelable] Android 13 compatibility extension.
 */
private inline fun <reified T : Parcelable> Parcel.readParcelableCompat(loader: ClassLoader?): T? {
    return if (android.os.Build.VERSION.SDK_INT < android.os.Build.VERSION_CODES.TIRAMISU) {
        @Suppress("DEPRECATION")
        readParcelable(loader)
    } else {
        readParcelable(loader, T::class.java)
    }
}

@Parcelize
enum class MessageStatus : Parcelable {
    UNKNOWN, // Not set for this message
    RECEIVED, // Came in from the mesh
    QUEUED, // Waiting to send to the mesh as soon as we connect to the device
    ENROUTE, // Delivered to the radio, but no ACK or NAK received
    DELIVERED, // We received an ack
    ERROR // We received back a nak, message not delivered
}

/**
 * A parcelable version of the protobuf MeshPacket + Data subpacket.
 */
@Serializable
data class DataPacket(
    var to: String? = ID_BROADCAST, // a nodeID string, or ID_BROADCAST for broadcast
    val bytes: ByteArray?,
    val dataType: Int, // A port number for this packet (formerly called DataType, see portnums.proto for new usage instructions)
    var from: String? = ID_LOCAL, // a nodeID string, or ID_LOCAL for localhost
    var time: Long = System.currentTimeMillis(), // msecs since 1970
    var id: Int = 0, // 0 means unassigned
    var status: MessageStatus? = MessageStatus.UNKNOWN,
    var hopLimit: Int = 0,
    var channel: Int = 0, // channel index
    var wantAck: Boolean = true, // If true, the receiver should send an ack back
) : Parcelable {

    /**
     * If there was an error with this message, this string describes what was wrong.
     */
    var errorMessage: String? = null

    /**
     * Syntactic sugar to make it easy to create text messages
     */
    constructor(to: String?, channel: Int, text: String) : this(
        to = to,
        bytes = text.encodeToByteArray(),
        dataType = Portnums.PortNum.TEXT_MESSAGE_APP_VALUE,
        channel = channel
    )

    /**
     * If this is a text message, return the string, otherwise null
     */
    val text: String?
        get() = if (dataType == Portnums.PortNum.TEXT_MESSAGE_APP_VALUE) {
            bytes?.decodeToString()
        } else {
            null
        }

    val alert: String?
        get() = if (dataType == Portnums.PortNum.ALERT_APP_VALUE) {
            bytes?.decodeToString()
        } else {
            null
        }

    constructor(to: String?, channel: Int, waypoint: MeshProtos.Waypoint) : this(
        to = to,
        bytes = waypoint.toByteArray(),
        dataType = Portnums.PortNum.WAYPOINT_APP_VALUE,
        channel = channel
    )

    val waypoint: MeshProtos.Waypoint?
        get() = if (dataType == Portnums.PortNum.WAYPOINT_APP_VALUE) {
            MeshProtos.Waypoint.parseFrom(bytes)
        } else {
            null
        }

    // Autogenerated comparision, because we have a byte array

    constructor(parcel: Parcel) : this(
        parcel.readString(),
        parcel.createByteArray(),
        parcel.readInt(),
        parcel.readString(),
        parcel.readLong(),
        parcel.readInt(),
        parcel.readParcelableCompat(MessageStatus::class.java.classLoader),
        parcel.readInt(),
        parcel.readInt(),
        parcel.readInt() == 1,
    )

    override fun equals(other: Any?): Boolean {
        if (this === other) return true
        if (javaClass != other?.javaClass) return false

        other as DataPacket

        if (from != other.from) return false
        if (to != other.to) return false
        if (channel != other.channel) return false
        if (time != other.time) return false
        if (id != other.id) return false
        if (dataType != other.dataType) return false
        if (!bytes!!.contentEquals(other.bytes!!)) return false
        if (status != other.status) return false
        if (hopLimit != other.hopLimit) return false
        if (wantAck != other.wantAck) return false

        return true
    }

    override fun hashCode(): Int {
        var result = from.hashCode()
        result = 31 * result + to.hashCode()
        result = 31 * result + time.hashCode()
        result = 31 * result + id
        result = 31 * result + dataType
        result = 31 * result + bytes!!.contentHashCode()
        result = 31 * result + status.hashCode()
        result = 31 * result + hopLimit
        result = 31 * result + channel
        result = 31 * result + wantAck.hashCode()
        return result
    }

    override fun writeToParcel(parcel: Parcel, flags: Int) {
        parcel.writeString(to)
        parcel.writeByteArray(bytes)
        parcel.writeInt(dataType)
        parcel.writeString(from)
        parcel.writeLong(time)
        parcel.writeInt(id)
        parcel.writeParcelable(status, flags)
        parcel.writeInt(hopLimit)
        parcel.writeInt(channel)
        parcel.writeInt(if (wantAck) 1 else 0)
    }

    override fun describeContents(): Int {
        return 0
    }

    // Update our object from our parcel (used for inout parameters
    fun readFromParcel(parcel: Parcel) {
        to = parcel.readString()
        parcel.createByteArray()
        parcel.readInt()
        from = parcel.readString()
        time = parcel.readLong()
        id = parcel.readInt()
        status = parcel.readParcelableCompat(MessageStatus::class.java.classLoader)
        hopLimit = parcel.readInt()
        channel = parcel.readInt()
        wantAck = parcel.readInt() == 1
    }

    companion object CREATOR : Parcelable.Creator<DataPacket> {
        // Special node IDs that can be used for sending messages

        /** the Node ID for broadcast destinations */
        const val ID_BROADCAST = "^all"

        /** The Node ID for the local node - used for from when sender doesn't know our local node ID */
        const val ID_LOCAL = "^local"

        // special broadcast address
        const val NODENUM_BROADCAST = (0xffffffff).toInt()

        // Public-key cryptography (PKC) channel index
        const val PKC_CHANNEL_INDEX = 8

        fun nodeNumToDefaultId(n: Int): String = "!%08x".format(n)
        fun idToDefaultNodeNum(id: String?): Int? = runCatching { id?.toLong(16)?.toInt() }.getOrNull()

        override fun createFromParcel(parcel: Parcel): DataPacket {
            return DataPacket(parcel)
        }

        override fun newArray(size: Int): Array<DataPacket?> {
            return arrayOfNulls(size)
        }
    }
}