Add DateTimeHelper.kt

app/src/main/java/chat/rocket/android/app/DateTimeHelper.kt

+import android.content.Context
+import chat.rocket.android.R
+import org.threeten.bp.DayOfWeek
+import org.threeten.bp.LocalDate
+import org.threeten.bp.LocalDateTime
+import org.threeten.bp.Period
+import org.threeten.bp.format.DateTimeFormatter
+import org.threeten.bp.format.FormatStyle
+import org.threeten.bp.temporal.ChronoUnit
+
+object DateTimeHelper {
+    private val today = LocalDate.now()
+    private val yesterday = today.minusDays(1)
+    private val lastWeek = today.minus(1, ChronoUnit.WEEKS)
+
+    /**
+     * Returns a date or the correlated expression from a LocalDateTime.
+     * REMARK: this will return "today", "yesterday", the day of the week or the localDate if the LocalDateTime is from a week ago.
+     *
+     * @param localDateTime The LocalDateTime.
+     * @param context The context.
+     * @return The date or the correlated expression from a LocalDateTime.
+     */
+    fun getDate(localDateTime: LocalDateTime, context: Context): String {
+        val localDate = localDateTime.toLocalDate()
+        return when (localDate) {
+            today -> localDateTime.toLocalTime().toString()
+            yesterday -> context.getString(R.string.msg_yesterday)
+            else -> {
+                if (Period.between(lastWeek, localDate).days <= 0) {
+                    formatDate(localDate)
+                } else {
+                    when (localDateTime.dayOfWeek) {
+                        DayOfWeek.MONDAY -> context.getString(R.string.msg_monday)
+                        DayOfWeek.TUESDAY -> context.getString(R.string.msg_tuesday)
+                        DayOfWeek.WEDNESDAY -> context.getString(R.string.msg_wednesday)
+                        DayOfWeek.THURSDAY -> context.getString(R.string.msg_thursday)
+                        DayOfWeek.FRIDAY -> context.getString(R.string.msg_friday)
+                        DayOfWeek.SATURDAY -> context.getString(R.string.msg_saturday)
+                        else -> context.getString(R.string.msg_sunday)
+                    }
+                }
+            }
+        }
+    }
+
+    private fun formatDate(localDate: LocalDate): String {
+        val formatter = DateTimeFormatter.ofLocalizedDate(FormatStyle.SHORT)
+        return localDate.format(formatter).toString()
+    }
+}
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