add new comparator enum

app/src/main/java/net/pokeranalytics/android/model/comparison/Comparator.kt

@@ -0,0 +1,73 @@
+package net.pokeranalytics.android.model.comparison
+
+import io.realm.Realm
+import io.realm.RealmQuery
+import io.realm.kotlin.where
+import net.pokeranalytics.android.exceptions.PokerAnalyticsException
+import net.pokeranalytics.android.model.filter.Filterable
+import net.pokeranalytics.android.model.filter.QueryCondition
+
+enum class Comparator {
+    DAY_OF_WEEK,
+    MONTH,
+    BLIND,
+    ;
+
+    val queryConditions: List<QueryCondition>
+        get() {
+            return when (this) {
+                DAY_OF_WEEK -> listOf()
+                else -> throw PokerAnalyticsException.QueryTypeUnhandled
+            }
+        }
+
+}
+
+fun List<Comparator>.combined(): List<List<QueryCondition>> {
+    val comparatorList = ArrayList<List<QueryCondition>>()
+    this.forEach {
+        comparatorList.add(it.queryConditions)
+    }
+    return getCombinations(comparatorList)
+}
+
+inline fun <reified T : Filterable> List<QueryCondition>.query(realm: Realm): RealmQuery<T> {
+    var realmQuery = realm.where<T>()
+    this.forEach {
+        realmQuery = it.filter(realmQuery)
+    }
+    return realmQuery
+}
+
+fun <T> getCombinations(lists: List<List<T>>): List<List<T>> {
+    var combinations: MutableSet<List<T>> = HashSet()
+    var newCombinations: MutableSet<List<T>>
+
+    var index = 0
+
+    // extract each of the integers in the first list
+    // and add each to ints as a new list
+    for (i in lists[0]) {
+        val newList = ArrayList<T>()
+        newList.add(i)
+        combinations.add(newList)
+    }
+    index++
+    while (index < lists.size) {
+        val nextList = lists[index]
+        newCombinations = HashSet()
+        for (first in combinations) {
+            for (second in nextList) {
+                val newList = ArrayList<T>()
+                newList.addAll(first)
+                newList.add(second)
+                newCombinations.add(newList)
+            }
+        }
+        combinations = newCombinations
+
+        index++
+    }
+
+    return combinations.toList()
+}