Create ConfigManager.kt

src/main/kotlin/net/axay/kspigot/config/ConfigManager.kt

@@ -0,0 +1,108 @@
+@file:Suppress("MemberVisibilityCanBePrivate", "unused")
+
+package net.axay.kspigot.config
+
+import net.axay.kspigot.kotlinextensions.createIfNotExists
+import net.axay.kspigot.main.ValueHolder.getGson
+import java.io.File
+import java.io.FileReader
+import java.io.FileWriter
+import kotlin.reflect.KClass
+import kotlin.reflect.KProperty
+
+/**
+ * Creates a new ConfigDelegate object.
+ *
+ * You can use this as a delegate (with **by**) or
+ * a normal object.
+ * (Delegate allows direct access to the config
+ * object, but does not provide save() or reload()
+ * methods.)
+ *
+ * @param T The class type of the config.
+ * @param file The path to the config.
+ * @param default Optional default config, which will be
+ * used if there is no config file and a new one should
+ * be created.
+ * @throws java.io.FileNotFoundException If the file does not
+ * exist and no default config is specified.
+ */
+inline fun <reified T : Any> kSpigotJsonConfig(
+        file: File,
+        noinline default: (() -> T)? = null,
+) = ConfigDelegate(T::class, file, default)
+
+/**
+ * @see kSpigotJsonConfig
+ */
+class ConfigDelegate<T : Any> (
+        private val configClass: KClass<T>,
+        private val file: File,
+        private val defaultCallback: (() -> T)?
+) {
+
+    private var internalConfig: T = loadIt()
+
+    var data: T
+        get() = internalConfig
+        set(value) = saveIt(value)
+
+    operator fun getValue(thisRef: Any?, property: KProperty<*>) = internalConfig
+
+    operator fun setValue(thisRef: Any?, property: KProperty<*>, config: T): Boolean {
+        saveIt(config)
+        return true
+    }
+
+    /**
+     * Saves the config object in its current state to disk.
+     */
+    fun save() = saveIt(internalConfig)
+
+    /**
+     * Loads the current state of the config on disk to the config object.
+     */
+    fun reload() { loadIt() }
+
+    private fun saveIt(toSave: T) {
+        GsonConfigManager.saveConfig(file, toSave, true)
+        internalConfig = toSave
+    }
+
+    private fun loadIt()
+        = if (defaultCallback == null)
+            GsonConfigManager.loadConfig(file, configClass)
+        else
+            GsonConfigManager.loadOrCreateDefault(file, configClass, true, defaultCallback)
+
+}
+
+internal object GsonConfigManager {
+
+    fun <T : Any> loadConfig(file: File, configClass: KClass<T>): T
+            = FileReader(file).use { reader -> return getGson(false).fromJson(reader, configClass.java) }
+
+    fun <T : Any> saveConfig(file: File, config: T, pretty: Boolean = true) {
+        file.createIfNotExists()
+        FileWriter(file).use { writer ->
+            getGson(pretty).toJson(config, writer)
+        }
+    }
+
+    fun <T : Any> loadOrCreateDefault(
+        file: File,
+        configClass: KClass<T>,
+        pretty: Boolean = true,
+        default: () -> T
+    ): T {
+        try {
+            return loadConfig(file, configClass)
+        } catch (exc: Exception) {
+            default.invoke().let {
+                saveConfig(file, it, pretty)
+                return it
+            }
+        }
+    }
+
+}