@file:UseSerializers(BlockPosSerializer::class, IdentifierSerializer::class)

package moe.nea.firmament.features.texturepack

import java.util.concurrent.CompletableFuture
import java.util.concurrent.Executor
import java.util.function.Function
import net.fabricmc.loader.api.FabricLoader
import kotlinx.serialization.ExperimentalSerializationApi
import kotlinx.serialization.KSerializer
import kotlinx.serialization.Serializable
import kotlinx.serialization.Transient
import kotlinx.serialization.UseSerializers
import kotlinx.serialization.descriptors.SerialDescriptor
import kotlinx.serialization.encoding.Decoder
import kotlinx.serialization.encoding.Encoder
import kotlinx.serialization.json.JsonDecoder
import kotlinx.serialization.json.JsonElement
import kotlinx.serialization.json.JsonPrimitive
import kotlinx.serialization.serializer
import kotlin.jvm.optionals.getOrNull
import net.minecraft.block.Block
import net.minecraft.block.BlockState
import net.minecraft.client.render.model.Baker
import net.minecraft.client.render.model.BlockStateModel
import net.minecraft.client.render.model.ReferencedModelsCollector
import net.minecraft.client.render.model.SimpleBlockStateModel
import net.minecraft.client.render.model.json.ModelVariant
import net.minecraft.registry.RegistryKey
import net.minecraft.registry.RegistryKeys
import net.minecraft.resource.ResourceManager
import net.minecraft.resource.SinglePreparationResourceReloader
import net.minecraft.util.Identifier
import net.minecraft.util.math.BlockPos
import net.minecraft.util.profiler.Profiler
import net.minecraft.util.thread.AsyncHelper
import moe.nea.firmament.Firmament
import moe.nea.firmament.annotations.Subscribe
import moe.nea.firmament.events.EarlyResourceReloadEvent
import moe.nea.firmament.events.FinalizeResourceManagerEvent
import moe.nea.firmament.events.SkyblockServerUpdateEvent
import moe.nea.firmament.features.texturepack.CustomBlockTextures.createBakedModels
import moe.nea.firmament.features.texturepack.CustomGlobalTextures.logger
import moe.nea.firmament.util.IdentifierSerializer
import moe.nea.firmament.util.MC
import moe.nea.firmament.util.SBData
import moe.nea.firmament.util.SkyBlockIsland
import moe.nea.firmament.util.json.BlockPosSerializer
import moe.nea.firmament.util.json.SingletonSerializableList


object CustomBlockTextures {
	@Serializable
	data class CustomBlockOverride(
		val modes: @Serializable(SingletonSerializableList::class) List<String>,
		val area: List<Area>? = null,
		val replacements: Map<Identifier, Replacement>,
	)

	@Serializable(with = Replacement.Serializer::class)
	data class Replacement(
		val block: Identifier,
		val sound: Identifier?,
	) {

		@Transient
		val blockModelIdentifier get() = block.withPrefixedPath("block/")

		/**
		 * Guaranteed to be set after [BakedReplacements.modelBakingFuture] is complete.
		 */
		@Transient
		lateinit var blockModel: BlockStateModel

		@OptIn(ExperimentalSerializationApi::class)
		@kotlinx.serialization.Serializer(Replacement::class)
		object DefaultSerializer : KSerializer<Replacement>

		object Serializer : KSerializer<Replacement> {
			val delegate = serializer<JsonElement>()
			override val descriptor: SerialDescriptor
				get() = delegate.descriptor

			override fun deserialize(decoder: Decoder): Replacement {
				val jsonElement = decoder.decodeSerializableValue(delegate)
				if (jsonElement is JsonPrimitive) {
					require(jsonElement.isString)
					return Replacement(Identifier.tryParse(jsonElement.content)!!, null)
				}
				return (decoder as JsonDecoder).json.decodeFromJsonElement(DefaultSerializer, jsonElement)
			}

			override fun serialize(encoder: Encoder, value: Replacement) {
				encoder.encodeSerializableValue(DefaultSerializer, value)
			}
		}
	}

	@Serializable
	data class Area(
		val min: BlockPos,
		val max: BlockPos,
	) {
		@Transient
		val realMin = BlockPos(
			minOf(min.x, max.x),
			minOf(min.y, max.y),
			minOf(min.z, max.z),
		)

		@Transient
		val realMax = BlockPos(
			maxOf(min.x, max.x),
			maxOf(min.y, max.y),
			maxOf(min.z, max.z),
		)

		fun roughJoin(other: Area): Area {
			return Area(
				BlockPos(
					minOf(realMin.x, other.realMin.x),
					minOf(realMin.y, other.realMin.y),
					minOf(realMin.z, other.realMin.z),
				),
				BlockPos(
					maxOf(realMax.x, other.realMax.x),
					maxOf(realMax.y, other.realMax.y),
					maxOf(realMax.z, other.realMax.z),
				)
			)
		}

		fun contains(blockPos: BlockPos): Boolean {
			return (blockPos.x in realMin.x..realMax.x) &&
				(blockPos.y in realMin.y..realMax.y) &&
				(blockPos.z in realMin.z..realMax.z)
		}
	}

	data class LocationReplacements(
		val lookup: Map<Block, List<BlockReplacement>>
	)

	data class BlockReplacement(
		val checks: List<Area>?,
		val replacement: Replacement,
	) {
		val roughCheck by lazy(LazyThreadSafetyMode.NONE) {
			if (checks == null || checks.size < 3) return@lazy null
			checks.reduce { acc, next -> acc.roughJoin(next) }
		}
	}

	data class BakedReplacements(val data: Map<SkyBlockIsland, LocationReplacements>) {
		/**
		 * Fulfilled by [createBakedModels] which is called during model baking. Once completed, all [Replacement.blockModel] will be set.
		 */
		val modelBakingFuture = CompletableFuture<Unit>()

		/**
		 * @returns a list of all [Replacement]s.
		 */
		fun collectAllReplacements(): Sequence<Replacement> {
			return data.values.asSequence()
				.flatMap { it.lookup.values }
				.flatten()
				.map { it.replacement }
		}
	}

	var allLocationReplacements: BakedReplacements = BakedReplacements(mapOf())
	var currentIslandReplacements: LocationReplacements? = null

	fun refreshReplacements() {
		val location = SBData.skyblockLocation
		val replacements =
			if (CustomSkyBlockTextures.TConfig.enableBlockOverrides) location?.let(allLocationReplacements.data::get)
			else null
		val lastReplacements = currentIslandReplacements
		currentIslandReplacements = replacements
		if (lastReplacements != replacements) {
			MC.nextTick {
				MC.worldRenderer.chunks?.chunks?.forEach {
					// false schedules rebuilds outside a 27 block radius to happen async
					it.scheduleRebuild(false)
				}
				sodiumReloadTask?.run()
			}
		}
	}

	private val sodiumReloadTask = runCatching {
		val r = Class.forName("moe.nea.firmament.compat.sodium.SodiumChunkReloader")
			.getConstructor()
			.newInstance() as Runnable
		r.run()
		r
	}.getOrElse {
		if (FabricLoader.getInstance().isModLoaded("sodium"))
			logger.error("Could not create sodium chunk reloader")
		null
	}


	fun matchesPosition(replacement: BlockReplacement, blockPos: BlockPos?): Boolean {
		if (blockPos == null) return true
		val rc = replacement.roughCheck
		if (rc != null && !rc.contains(blockPos)) return false
		val areas = replacement.checks
		if (areas != null && !areas.any { it.contains(blockPos) }) return false
		return true
	}

	@JvmStatic
	fun getReplacementModel(block: BlockState, blockPos: BlockPos?): BlockStateModel? {
		return getReplacement(block, blockPos)?.blockModel
	}

	@JvmStatic
	fun getReplacement(block: BlockState, blockPos: BlockPos?): Replacement? {
		if (isInFallback() && blockPos == null) {
			return null
		}
		val replacements = currentIslandReplacements?.lookup?.get(block.block) ?: return null
		for (replacement in replacements) {
			if (replacement.checks == null || matchesPosition(replacement, blockPos))
				return replacement.replacement
		}
		return null
	}


	@Subscribe
	fun onLocation(event: SkyblockServerUpdateEvent) {
		refreshReplacements()
	}

	@Volatile
	var preparationFuture: CompletableFuture<BakedReplacements> = CompletableFuture.completedFuture(BakedReplacements(
		mapOf()))

	val insideFallbackCall = ThreadLocal.withInitial { 0 }

	@JvmStatic
	fun enterFallbackCall() {
		insideFallbackCall.set(insideFallbackCall.get() + 1)
	}

	fun isInFallback() = insideFallbackCall.get() > 0

	@JvmStatic
	fun exitFallbackCall() {
		insideFallbackCall.set(insideFallbackCall.get() - 1)
	}

	@Subscribe
	fun onEarlyReload(event: EarlyResourceReloadEvent) {
		preparationFuture = CompletableFuture
			.supplyAsync(
				{ prepare(event.resourceManager) }, event.preparationExecutor)
	}

	private fun prepare(manager: ResourceManager): BakedReplacements {
		val resources = manager.findResources("overrides/blocks") {
			it.namespace == "firmskyblock" && it.path.endsWith(".json")
		}
		val map = mutableMapOf<SkyBlockIsland, MutableMap<Block, MutableList<BlockReplacement>>>()
		for ((file, resource) in resources) {
			val json =
				Firmament.tryDecodeJsonFromStream<CustomBlockOverride>(resource.inputStream)
					.getOrElse { ex ->
						logger.error("Failed to load block texture override at $file", ex)
						continue
					}
			for (mode in json.modes) {
				val island = SkyBlockIsland.forMode(mode)
				val islandMpa = map.getOrPut(island, ::mutableMapOf)
				for ((blockId, replacement) in json.replacements) {
					val block = MC.defaultRegistries.getOrThrow(RegistryKeys.BLOCK)
						.getOptional(RegistryKey.of(RegistryKeys.BLOCK, blockId))
						.getOrNull()
					if (block == null) {
						logger.error("Failed to load block texture override at ${file}: unknown block '$blockId'")
						continue
					}
					val replacements = islandMpa.getOrPut(block.value(), ::mutableListOf)
					replacements.add(BlockReplacement(json.area, replacement))
				}
			}
		}

		return BakedReplacements(map.mapValues { LocationReplacements(it.value) })
	}

	@Subscribe
	fun onStart(event: FinalizeResourceManagerEvent) {
		event.resourceManager.registerReloader(object :
			                                       SinglePreparationResourceReloader<BakedReplacements>() {
			override fun prepare(manager: ResourceManager, profiler: Profiler): BakedReplacements {
				return preparationFuture.join().also {
					it.modelBakingFuture.join()
				}
			}

			override fun apply(prepared: BakedReplacements, manager: ResourceManager, profiler: Profiler?) {
				allLocationReplacements = prepared
				refreshReplacements()
			}
		})
	}

	fun simpleBlockModel(blockId: Identifier): SimpleBlockStateModel.Unbaked {
		// TODO: does this need to be shared between resolving and baking? I think not, but it would probably be wise to do so in the future.
		return SimpleBlockStateModel.Unbaked(
			ModelVariant(blockId)
		)
	}

	/**
	 * Used by [moe.nea.firmament.init.SectionBuilderRiser]
	 */

	@JvmStatic
	fun patchIndigo(original: BlockStateModel, pos: BlockPos?, state: BlockState): BlockStateModel {
		return getReplacementModel(state, pos) ?: original
	}

	@JvmStatic
	fun collectExtraModels(modelsCollector: ReferencedModelsCollector) {
		preparationFuture.join().collectAllReplacements()
			.forEach { modelsCollector.resolve(simpleBlockModel(it.blockModelIdentifier)) }
	}

	@JvmStatic
	fun createBakedModels(baker: Baker, executor: Executor): CompletableFuture<Void?> {
		return preparationFuture.thenComposeAsync(Function { replacements ->
			val byModel = replacements.collectAllReplacements().groupBy { it.blockModelIdentifier }
			val modelBakingTask = AsyncHelper.mapValues(byModel, { blockId, replacements ->
				val unbakedModel = SimpleBlockStateModel.Unbaked(
					ModelVariant(blockId)
				)
				val baked = unbakedModel.bake(baker)
				replacements.forEach {
					it.blockModel = baked
				}
			}, executor)
			modelBakingTask.thenAcceptAsync { replacements.modelBakingFuture.complete(Unit) }
		}, executor)
	}
}