Hatch Homework Project Docs

ConnectivityClient.kt

package co.hatch.deviceClientLib.connectivity

import androidx.annotation.WorkerThread
import co.hatch.deviceClientLib.model.Device

/**
 * Interface in charge of abstracting the implementation of general operations to deal with
 * hardware devices ([Device]) independently from the underling connectivity technologies they require.
 */
interface ConnectivityClient {

    /**
     * Discover [Device]s. This method must be called from a worker thread and it is safe to call
     * multiple times over time, on each run the list of discovered [Device]s will have
     * an up to date [Device.rssi] property.
     *
     * @return returns a list of [Device]s available
     */
    fun discoverDevices(): List<Device>

    /**
     * Perform a connection to the given [deviceId].
     *
     * @param deviceId unique identifier of the device to connect to.
     * @param onDeviceStateChangeListener instance for on-going callbacks on [Device] state changes
     *
     * @return true if the operation succeeded, [Device]s in this state will
     * reflect [Device.connected] as true, [Device.latestConnectedTime] will be set and it will
     * update itself over-time to reflect for how long it has been in
     * connected state [Device.elapsedSecsConnected], otherwise false
     *
     * @throws IllegalStateException when the given [deviceId] do not match any of the
     * discovered devices
     */
    @WorkerThread
    fun connectToDeviceBy(
        deviceId: String,
        onDeviceStateChangeListener: OnDeviceStateChangeListener
    ): Boolean

    /**
     * Perform a name update on the given [deviceId].
     *
     * @param deviceId unique identifier of the device to connect to.
     * @param updatedName new name to set for this [deviceId]
     *
     * @throws IllegalStateException when the given [deviceId] is not connected.
     */
    fun updateDeviceName(deviceId: String, updatedName: String): Boolean

    /**
     * Performs a disconnect to the given [deviceId].
     *
     * @throws IllegalStateException when the given [deviceId] do not match any of the
     * discovered devices
     * */
    fun disconnectFromDevice(deviceId: String): Boolean

    object Factory {

        private val client by lazy { FakeClient() }

        /**
         * Factory method to create the concrete [ConnectivityClient] implementation.
         */
        fun create(): ConnectivityClient = client
    }

    /**
     * Callback interface to communicate back to any consumer the [Device] state updates.
     */
    interface OnDeviceStateChangeListener {

        fun onDeviceStateChanged(deviceId: String, device: Device)
    }
}

Device.kt

package co.hatch.deviceClientLib.model

import java.util.*

/**
 * Data model to represent a device that can be discovered by this application.
 */
data class Device(
    /**
     * Unique identifier
     */
    val id: String,

    /**
     * Device name
     */
    val name: String,

    /**
     * RSSI stands for Received Signal Strength Indicator
     * This property represent how strong or week the signal to the device is. Values ranges from
     * approximately -50 to -90 where higher the number higher the signal strength.
     */
    val rssi: Int,

    /**
     * Flag that indicates if the device is currently connected or not
     */
    val connected: Boolean = false,

    /**
     * Keeps track for how long the device has been in connected state
     */
    val elapsedSecsConnected: Long = 0,

    /**
     * Keeps track of the last time this device has been in connected state
     */
    val latestConnectedTime: Date? = null,
)