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@karntrehan
Last active July 26, 2019 06:32
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Synk: A simple Kotlin file to abstract a hybrid syncing technique for your Android apps
import android.content.Context
import android.content.SharedPreferences
import android.preference.PreferenceManager
import org.joda.time.DateTime
import org.joda.time.format.ISODateTimeFormat
import java.util.concurrent.TimeUnit
/**
* A Singleton object to identify if a sync operation should run or not.
* */
object Synk {
private var preferences: SharedPreferences? = null
const val TAG = "Synk"
private const val SYNK_IT = true
private const val DONT_SYNK = false
/**
* Initialize the preference object to read and write sync operation date-times.
* Preferably should be initialized in the application class.
**/
fun init(context: Context) {
preferences = PreferenceManager.getDefaultSharedPreferences(context)
}
/**
* Check if the sync operation should run or not.
*
* Note: Requires the [init] function to be called beforehand once per application run time.
*
* @param key key of the sync operation
* @param window amount of the delay between successive syncs
* @param unit [TimeUnit] of [window]
* @return [Boolean] to be checked if the sync should run
*
* @throws IllegalStateException if [unit] is [TimeUnit.MILLISECONDS], [TimeUnit.NANOSECONDS], [TimeUnit.MICROSECONDS] or [TimeUnit.SECONDS]
**/
fun shouldSync(key: String, window: Int = 4, unit: TimeUnit = TimeUnit.HOURS): Boolean {
performPrefsSanityCheck()
if (unit == TimeUnit.MILLISECONDS
|| unit == TimeUnit.NANOSECONDS
|| unit == TimeUnit.MICROSECONDS
|| unit == TimeUnit.SECONDS
)
throw IllegalStateException("Illegal time window")
val currentSavedValue = preferences?.getString(key, "")
if (currentSavedValue.isNullOrEmpty()) //Operation has never run or Synk doesn't know about it
return syncIt(key)
val syncedTime = DateTime.parse(currentSavedValue)
val syncBlock = when (unit) { //Identify the block window from last sync
TimeUnit.MINUTES -> syncedTime.plusMinutes(window)
TimeUnit.HOURS -> syncedTime.plusHours(window)
TimeUnit.DAYS -> syncedTime.plusDays(window)
else -> syncedTime
}
//Is the current time past the sync block window?
return if (DateTime.now() >= syncBlock) syncIt(key) else DONT_SYNK
}
/**
* Tell Synk that the sync operation was a success.
*
* This function saves the current time with the passed key into preferences.
*
* @param key String key of the sync operation
**/
fun syncSuccess(key: String) {
performPrefsSanityCheck()
saveSyncTime(key)
}
/**
* Tell Synk that the sync operation was a failure.
*
* This function removes the passed key from preferences.
*
* @param key String key of the sync operation
**/
fun syncFailure(key: String) {
performPrefsSanityCheck()
preferences
?.edit()
?.remove(key)
?.apply()
}
/**
* Checks if the preferences object has been initialized.
*
* @throws IllegalStateException if prefs not initialized
**/
private fun performPrefsSanityCheck() {
if (preferences == null)
throw IllegalStateException("Make sure to init Synk")
}
/**
* Triggers a save into preferences with current time for mentioned key,
* preventing multiple sync calls if first call is still under progress.
*
* @param key key of the sync operation
**/
private fun syncIt(key: String): Boolean {
saveSyncTime(key)
return SYNK_IT
}
/**
* Saves the mentioned datetime into the preferences in ISODateTimeFormat string.
*
* @param key key of the sync operation
* @param dateTime [DateTime] to be saved.
* */
private fun saveSyncTime(key: String, dateTime: DateTime = DateTime.now()) {
preferences
?.edit()
?.putString(key, ISODateTimeFormat.dateTime().print(dateTime))
?.apply()
}
}
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