KStarbound/src/main/kotlin/ru/dbotthepony/kstarbound/ObjectRegistry.kt

package ru.dbotthepony.kstarbound

import com.google.gson.Gson
import com.google.gson.JsonArray
import com.google.gson.JsonElement
import com.google.gson.JsonObject
import com.google.gson.JsonPrimitive
import com.google.gson.internal.bind.JsonTreeReader
import it.unimi.dsi.fastutil.ints.Int2ObjectMap
import it.unimi.dsi.fastutil.ints.Int2ObjectMaps
import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap
import it.unimi.dsi.fastutil.objects.Object2ObjectOpenHashMap
import org.apache.logging.log4j.LogManager
import ru.dbotthepony.kstarbound.api.IStarboundFile
import ru.dbotthepony.kstarbound.lua.LuaState
import ru.dbotthepony.kstarbound.util.AssetPathStack
import ru.dbotthepony.kstarbound.util.set
import ru.dbotthepony.kstarbound.util.traverseJsonPath
import java.util.*
import kotlin.reflect.KClass

inline fun <reified T : Any> ObjectRegistry(name: String, noinline key: ((T) -> String)? = null, noinline intKey: ((T) -> Int)? = null): ObjectRegistry<T> {
	return ObjectRegistry(T::class, name, key, intKey)
}

fun mergeJsonElements(source: JsonObject, destination: JsonObject): JsonObject {
	for ((k, v) in source.entrySet()) {
		if (!destination.has(k)) {
			destination[k] = v.deepCopy()
		} else {
			mergeJsonElements(v, destination[k])
		}
	}

	return destination
}

fun mergeJsonElements(source: JsonArray, destination: JsonArray): JsonArray {
	for ((i, v) in source.withIndex()) {
		if (i >= destination.size()) {
			destination.add(v.deepCopy())
		} else {
			destination[i] = mergeJsonElements(v, destination[i])
		}
	}

	return destination
}

fun mergeJsonElements(source: JsonElement, destination: JsonElement): JsonElement {
	if (destination is JsonPrimitive) {
		return destination
	}

	if (destination is JsonObject && source is JsonObject) {
		return mergeJsonElements(source, destination)
	}

	if (destination is JsonArray && source is JsonArray) {
		return mergeJsonElements(source, destination)
	}

	return destination
}

class RegistryObject<T : Any>(
	/**
	 * Объект реестра
	 */
	val value: T,
	/**
	 * Оригинальный JSON объекта без каких либо изменений
	 */
	val json: JsonElement,
	/**
	 * Файл, откуда данный объект был загружен
	 */
	val file: IStarboundFile,
) {
	val jsonObject get() = json as JsonObject

	fun push(lua: LuaState) {
		lua.push(toJson())
	}

	fun push(lua: LuaState.ArgStack) {
		lua.push(toJson())
	}

	/**
	 * Возвращает полную (обработанную) структуру [JsonObject] объекта [value]
	 *
	 * Полнота определяется тем, что [value] может иметь свойства по умолчанию, которые не указаны
	 * в оригинальной JSON структуре. [copy] не вернёт данные свойства по умолчанию, а [toJson] вернёт.
	 */
	fun toJson(): JsonElement {
		return mergeJsonElements(json, Starbound.gson.toJsonTree(value))
	}

	fun traverseJsonPath(path: String): JsonElement? {
		return traverseJsonPath(path, mergeJsonElements(json, Starbound.gson.toJsonTree(value)))
	}

	override fun equals(other: Any?): Boolean {
		return other === this || other is RegistryObject<*> && other.value == value && other.json == json
	}

	private var computedHash = false
	private var hash = 0

	override fun hashCode(): Int {
		if (!computedHash) {
			hash = value.hashCode().rotateRight(13) xor json.hashCode()
			computedHash = true
		}

		return hash
	}

	override fun toString(): String {
		return "RegistryObject[$value from $file]"
	}
}

class ObjectRegistry<T : Any>(val clazz: KClass<T>, val name: String, val key: ((T) -> String)? = null, val intKey: ((T) -> Int)? = null) {
	private val objects = Object2ObjectOpenHashMap<String, RegistryObject<T>>()
	private val intObjects = Int2ObjectOpenHashMap<RegistryObject<T>>()

	val view: Map<String, RegistryObject<T>> = Collections.unmodifiableMap(objects)
	val intView: Int2ObjectMap<RegistryObject<T>> = Int2ObjectMaps.unmodifiable(intObjects)

	fun clear() {
		objects.clear()
		intObjects.clear()
	}

	fun add(file: IStarboundFile): Boolean {
		return AssetPathStack(file.computeDirectory()) {
			val elem = Starbound.gson.fromJson(file.reader(), JsonElement::class.java)
			val value = Starbound.gson.fromJson<T>(JsonTreeReader(elem), clazz.java)
			add(RegistryObject(value, elem, file), this.key?.invoke(value) ?: throw UnsupportedOperationException("No key mapper"))
		}
	}

	fun add(value: T, json: JsonElement, file: IStarboundFile): Boolean {
		return add(RegistryObject(value, json, file), this.key?.invoke(value) ?: throw UnsupportedOperationException("No key mapper"))
	}

	fun add(value: T, json: JsonElement, file: IStarboundFile, key: String): Boolean {
		return add(RegistryObject(value, json, file), key)
	}

	private fun add(value: RegistryObject<T>, key: String): Boolean {
		val existing = objects.put(key, value)

		if (existing != null) {
			LOGGER.warn("Registry $name already has object with key $key! Overwriting. (old originated from ${existing.file}, new originate from ${value.file}).")
		}

		if (this.intKey == null)
			return existing != null

		val intKey = this.intKey.invoke(value.value)
		val intExisting = intObjects.put(intKey, value)

		if (intExisting != null) {
			LOGGER.warn("Registry $name already has object with ID $intKey (new $key, old ${ objects.entries.firstOrNull { it.value === intExisting }?.key })! Overwriting. (old originated from ${intExisting.file}, new originate from ${value.file}).")
		}

		return existing != null || intExisting != null
	}

	companion object {
		private val LOGGER = LogManager.getLogger()
	}
}