package ru.dbotthepony.kstarbound.client.render

import com.github.benmanes.caffeine.cache.Cache
import com.github.benmanes.caffeine.cache.Caffeine
import com.github.benmanes.caffeine.cache.Scheduler
import org.apache.logging.log4j.LogManager
import org.lwjgl.opengl.GL45.*
import ru.dbotthepony.kommons.math.RGBAColor
import ru.dbotthepony.kstarbound.math.vector.Vector2i
import ru.dbotthepony.kstarbound.world.PIXELS_IN_STARBOUND_UNITf
import ru.dbotthepony.kstarbound.Registries
import ru.dbotthepony.kstarbound.Starbound
import ru.dbotthepony.kstarbound.client.StarboundClient
import ru.dbotthepony.kstarbound.client.gl.*
import ru.dbotthepony.kstarbound.client.gl.shader.UberShader
import ru.dbotthepony.kstarbound.client.gl.vertex.*
import ru.dbotthepony.kstarbound.defs.tile.*
import ru.dbotthepony.kstarbound.util.random.staticRandomFloat
import ru.dbotthepony.kstarbound.world.api.ITileAccess
import ru.dbotthepony.kstarbound.world.api.AbstractTileState
import ru.dbotthepony.kstarbound.world.api.TileColor
import java.time.Duration
import java.util.concurrent.Callable
import kotlin.math.roundToInt

/**
 * Хранит в себе программы для отрисовки определённых [TileDefinition]
 *
 * Создаётся единожды как потомок [Graphics]
 */
class TileRenderers(val client: StarboundClient) {
	private val foreground: Cache<GLTexture2D, Config> = Caffeine.newBuilder()
		.expireAfterAccess(Duration.ofMinutes(5))
		.scheduler(Starbound)
		.build()

	private val background: Cache<GLTexture2D, Config> = Caffeine.newBuilder()
		.expireAfterAccess(Duration.ofMinutes(5))
		.scheduler(Starbound)
		.build()

	private val matCache: Cache<String, TileRenderer> = Caffeine.newBuilder()
		.expireAfterAccess(Duration.ofMinutes(5))
		.scheduler(Starbound)
		.build()

	private val modCache: Cache<String, TileRenderer> = Caffeine.newBuilder()
		.expireAfterAccess(Duration.ofMinutes(5))
		.scheduler(Starbound)
		.build()

	fun getMaterialRenderer(defName: String): TileRenderer {
		return matCache.get(defName) {
			val def = Registries.tiles[defName] // TODO: Пустой рендерер
			client.mailbox.submit(Callable { TileRenderer(this, def!!.value) }).get()
		}
	}

	fun getModifierRenderer(defName: String): TileRenderer {
		return modCache.get(defName) {
			val def = Registries.tileModifiers[defName] // TODO: Пустой рендерер
			client.mailbox.submit(Callable { TileRenderer(this, def!!.value) }).get()
		}
	}

	private inner class Config(private val texture: GLTexture2D, private val color: RGBAColor) : RenderConfig<UberShader>(client.programs.tile) {
		override val initialBuilderCapacity: Int
			get() = 1024

		override fun setup() {
			super.setup()
			client.depthTest = false
			program.texture0 = 0
			client.textures2D[0] = texture
			texture.textureMagFilter = GL_NEAREST
			texture.textureMinFilter = GL_NEAREST

			program.modelMatrix = client.stack.last()
			program.colorMultiplier = color
		}

		override fun uninstall() {}
	}

	fun foreground(texture: GLTexture2D): RenderConfig<UberShader> {
		return foreground.get(texture) { Config(it, FOREGROUND_COLOR) }
	}

	fun background(texture: GLTexture2D): RenderConfig<UberShader> {
		return background.get(texture) { Config(it, BACKGROUND_COLOR) }
	}

	companion object {
		val BACKGROUND_COLOR = RGBAColor(0.4f, 0.4f, 0.4f)
		val FOREGROUND_COLOR = RGBAColor(1f, 1f, 1f)
	}
}

private class TileEqualityTester(val definition: TileDefinition) : EqualityRuleTester {
	override fun test(thisTile: AbstractTileState?, otherTile: AbstractTileState?): Boolean {
		return otherTile?.material?.value == definition && thisTile?.hueShift == otherTile.hueShift
	}
}

private class ModifierEqualityTester(val definition: TileModifierDefinition) : EqualityRuleTester {
	override fun test(thisTile: AbstractTileState?, otherTile: AbstractTileState?): Boolean {
		return otherTile?.modifier?.value == definition
	}
}

class TileRenderer(val renderers: TileRenderers, val def: IRenderableTile) {
	private enum class TestResult {
		NO_MATCH,
		CONTINUE,
		HALT
	}

	val client get() = renderers.client
	val texture = def.renderParameters.texture?.image?.texture?.also { it.textureMagFilter = GL_NEAREST }

	val equalityTester: EqualityRuleTester = when (def) {
		is TileDefinition -> TileEqualityTester(def)
		is TileModifierDefinition -> ModifierEqualityTester(def)
		else -> throw IllegalStateException()
	}

	val bakedProgramState = texture?.let { renderers.foreground(it) }
	val bakedBackgroundProgramState = texture?.let { renderers.background(it) }
	// private var notifiedDepth = false

	private fun tesselateAt(self: AbstractTileState, piece: RenderPiece, getter: ITileAccess, builder: VertexBuilder, pos: Vector2i, offset: Vector2i = Vector2i.ZERO, isModifier: Boolean) {
		val fx = pos.x.toFloat()
		val fy = pos.y.toFloat()

		var a = fx
		var b = fy

		var c = fx + piece.textureSize.x / PIXELS_IN_STARBOUND_UNITf
		var d = fy + piece.textureSize.y / PIXELS_IN_STARBOUND_UNITf

		if (offset != Vector2i.ZERO) {
			a += offset.x / PIXELS_IN_STARBOUND_UNITf

			// в json файлах Y указан как положительный вверх,
			// что соответствует нашему миру
			b += offset.y / PIXELS_IN_STARBOUND_UNITf

			c += offset.x / PIXELS_IN_STARBOUND_UNITf
			d += offset.y / PIXELS_IN_STARBOUND_UNITf
		}

		var mins = piece.texturePosition
		var maxs = piece.texturePosition + piece.textureSize

		if (def.renderParameters.variants != 0 && piece.variantStride != null && piece.image == null) {
			val variant = (staticRandomFloat("TileVariant", pos.x, pos.y) * def.renderParameters.variants).roundToInt()
			mins += piece.variantStride * variant
			maxs += piece.variantStride * variant
		}

		if (def.renderParameters.multiColored && piece.colorStride != null && self.color != TileColor.DEFAULT) {
			mins += piece.colorStride * self.color.ordinal
			maxs += piece.colorStride * self.color.ordinal
		}

		val (u0, v0) = texture!!.pixelToUV(mins)
		val (u1, v1) = texture.pixelToUV(maxs)

		val hue = if (isModifier) self.modifierHueShift else self.hueShift

		// flip uv since in-world coordinates are flipped relative to screen
		builder.vertex(a, b).uv(u0, v1).hueShift(hue)
		builder.vertex(c, b).uv(u1, v1).hueShift(hue)
		builder.vertex(c, d).uv(u1, v0).hueShift(hue)
		builder.vertex(a, d).uv(u0, v0).hueShift(hue)
	}

	private fun tesselatePiece(
		self: AbstractTileState,
		matchPiece: RenderMatch,
		getter: ITileAccess,
		meshBuilder: LayeredRenderer,
		pos: Vector2i,
		thisBuilder: VertexBuilder,
		isBackground: Boolean,
		isModifier: Boolean,
	): TestResult {
		if (matchPiece.test(getter, equalityTester, pos)) {
			for (renderPiece in matchPiece.pieces) {
				if (renderPiece.piece.image != null) {
					val program = if (isBackground) {
						renderers.background(renderPiece.piece.image!!.texture)
					} else {
						renderers.foreground(renderPiece.piece.image!!.texture)
					}

					tesselateAt(
						self, renderPiece.piece, getter,
						meshBuilder.getBuilder(RenderLayer.tileLayer(isBackground, isModifier, self), program).mode(GeometryType.QUADS),
						pos, renderPiece.offset, isModifier)
				} else {
					tesselateAt(self, renderPiece.piece, getter, thisBuilder, pos, renderPiece.offset, isModifier)
				}
			}

			for (subPiece in matchPiece.subMatches) {
				val matched = tesselatePiece(self, subPiece, getter, meshBuilder, pos, thisBuilder, isBackground, isModifier)

				if (matched == TestResult.HALT || matched == TestResult.CONTINUE && matchPiece.haltOnSubMatch) {
					return TestResult.HALT
				}
			}

			if (matchPiece.haltOnMatch) {
				return TestResult.HALT
			}

			return TestResult.CONTINUE
		}

		return TestResult.NO_MATCH
	}

	/**
	 * Тесселирует тайлы в заданной позиции в нужном билдере
	 *
	 * [getter] Нужен для получения информации о ближайших блоках
	 *
	 * [meshBuilder] содержит текущие программы и их билдеры и их zPos
	 *
	 * Тесселирует тайлы в нужный VertexBuilder с масштабом согласно константе [PIXELS_IN_STARBOUND_UNITf]
	 */
	fun tesselate(self: AbstractTileState, getter: ITileAccess, meshBuilder: LayeredRenderer, pos: Vector2i, isBackground: Boolean = false, isModifier: Boolean = false) {
		if (texture == null) return

		// если у нас нет renderTemplate
		// то мы просто не можем его отрисовать
		val template = def.renderTemplate.value ?: return

		val vertexBuilder = meshBuilder
			.getBuilder(RenderLayer.tileLayer(isBackground, isModifier, self), if (isBackground) bakedBackgroundProgramState!! else bakedProgramState!!)
			.mode(GeometryType.QUADS)

		for ((_, matcher) in template.matches) {
			for (matchPiece in matcher) {
				val matched = tesselatePiece(self, matchPiece, getter, meshBuilder, pos, vertexBuilder, isBackground, isModifier)

				if (matched == TestResult.HALT) {
					break
				}
			}
		}
	}

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