Added global preferences object

app/src/main/java/xyz/quaver/pupil/util/Preferences.kt

@@ -0,0 +1,55 @@
+/*
+ *     Pupil, Hitomi.la viewer for Android
+ *     Copyright (C) 2020  tom5079
+ *
+ *     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 <http://www.gnu.org/licenses/>.
+ */
+
+package xyz.quaver.pupil.util
+
+import android.content.SharedPreferences
+import kotlin.reflect.KClass
+
+lateinit var preferences: SharedPreferences
+
+object Preferences: SharedPreferences by preferences {
+
+    @Suppress("UNCHECKED_CAST")
+    val putMap = mapOf<KClass<out Any>, (String, Any) -> Unit>(
+        String::class to { k, v -> edit().putString(k, v as String).apply() },
+        Int::class to { k, v -> edit().putBoolean(k, v as Boolean).apply() },
+        Long::class to { k, v -> edit().putLong(k, v as Long).apply() },
+        Boolean::class to { k, v -> edit().putBoolean(k, v as Boolean).apply() },
+        Set::class to { k, v -> edit().putStringSet(k, v as Set<String>).apply() }
+    )
+
+    val defMap = mapOf(
+        String::class to "",
+        Int::class to -1,
+        Long::class to -1,
+        Boolean::class to false,
+        Set::class to emptySet<Any>()
+    )
+
+    inline operator fun <reified T: Any> set(key: String, value: T) {
+        putMap[T::class]?.invoke(key, value)
+    }
+
+    inline operator fun <reified T: Any> get(key: String, defaultVal: T = defMap[T::class] as T, setIfNull: Boolean = false): T =
+        (all[key] as? T) ?: defaultVal.also { if (setIfNull) set(key, defaultVal) }
+
+    fun remove(key: String) {
+        edit().remove(key).apply()
+    }
+}