KStarbound/src/main/kotlin/ru/dbotthepony/kstarbound/client/gl/GLStateTracker.kt

package ru.dbotthepony.kstarbound.client.gl

import org.apache.logging.log4j.LogManager
import org.lwjgl.opengl.GL
import org.lwjgl.opengl.GL46.*
import ru.dbotthepony.kstarbound.Starbound
import ru.dbotthepony.kstarbound.client.freetype.FreeType
import ru.dbotthepony.kstarbound.client.freetype.InvalidArgumentException
import ru.dbotthepony.kstarbound.client.gl.program.GLPrograms
import ru.dbotthepony.kstarbound.client.gl.shader.GLShader
import ru.dbotthepony.kstarbound.client.gl.program.GLShaderProgram
import ru.dbotthepony.kstarbound.client.gl.shader.GLTransformableColorableProgram
import ru.dbotthepony.kstarbound.client.gl.shader.GLTransformableProgram
import ru.dbotthepony.kstarbound.client.gl.vertex.GLAttributeList
import ru.dbotthepony.kstarbound.client.gl.vertex.StreamVertexBuilder
import ru.dbotthepony.kstarbound.client.gl.vertex.GeometryType
import ru.dbotthepony.kstarbound.client.gl.vertex.quad
import ru.dbotthepony.kstarbound.client.render.Box2DRenderer
import ru.dbotthepony.kstarbound.client.render.Font
import ru.dbotthepony.kstarbound.client.render.TileRenderers
import ru.dbotthepony.kvector.api.IStruct4f
import ru.dbotthepony.kvector.matrix.Matrix4fStack
import ru.dbotthepony.kvector.util2d.AABB
import ru.dbotthepony.kvector.vector.Color
import java.io.FileNotFoundException
import java.lang.ref.Cleaner
import java.util.concurrent.ThreadFactory
import kotlin.collections.ArrayList
import kotlin.collections.HashMap
import kotlin.properties.ReadWriteProperty
import kotlin.reflect.KProperty

private class GLStateSwitchTracker(private val enum: Int, private var value: Boolean = false) {
	operator fun getValue(glStateTracker: GLStateTracker, property: KProperty<*>): Boolean {
		return value
	}

	operator fun setValue(glStateTracker: GLStateTracker, property: KProperty<*>, value: Boolean) {
		glStateTracker.ensureSameThread()

		if (value == this.value)
			return

		if (value) {
			glEnable(enum)
		} else {
			glDisable(enum)
		}

		checkForGLError()
		this.value = value
	}
}

private class GLStateFuncTracker(private val glFunc: (Int) -> Unit, private var value: Int) {
	operator fun getValue(glStateTracker: GLStateTracker, property: KProperty<*>): Int {
		return value
	}

	operator fun setValue(glStateTracker: GLStateTracker, property: KProperty<*>, value: Int) {
		glStateTracker.ensureSameThread()

		if (value == this.value)
			return

		glFunc.invoke(value)
		checkForGLError()
		this.value = value
	}
}

private class GLStateGenericTracker<T>(private var value: T, private val callback: (T) -> Unit) : ReadWriteProperty<GLStateTracker, T> {
	override fun getValue(thisRef: GLStateTracker, property: KProperty<*>): T {
		return value
	}

	override fun setValue(thisRef: GLStateTracker, property: KProperty<*>, value: T) {
		thisRef.ensureSameThread()

		if (value == this.value)
			return

		callback.invoke(value)
		checkForGLError()
		this.value = value
	}
}

private class TexturesTracker(maxValue: Int) : ReadWriteProperty<GLStateTracker, GLTexture2D?> {
	private val values = arrayOfNulls<GLTexture2D>(maxValue)

	override fun getValue(thisRef: GLStateTracker, property: KProperty<*>): GLTexture2D? {
		return values[thisRef.activeTexture]
	}

	override fun setValue(thisRef: GLStateTracker, property: KProperty<*>, value: GLTexture2D?) {
		thisRef.ensureSameThread()

		require(value == null || thisRef === value.state) { "$value does not belong to $thisRef" }

		if (values[thisRef.activeTexture] === value) {
			return
		}

		values[thisRef.activeTexture] = value

		if (value == null) {
			glBindTexture(GL_TEXTURE_2D, 0)
			checkForGLError()
			return
		}

		glBindTexture(GL_TEXTURE_2D, value.pointer)
		checkForGLError()
	}
}

@Suppress("unused")
data class BlendFunc(
	val sourceColor: Func,
	val destinationColor: Func,
	val sourceAlpha: Func,
	val destinationAlpha: Func
) {
	constructor() : this(
		Func.ONE,
		Func.ZERO,
		Func.ONE,
		Func.ZERO
	)

	constructor(
		source: Func, destination: Func
	) : this(
		source,
		destination,
		source,
		destination
	)

	enum class Func(val enum: Int) {
		ZERO(GL_ZERO),
		ONE(GL_ONE),
		SRC_COLOR(GL_SRC_COLOR),
		ONE_MINUS_SRC_COLOR(GL_ONE_MINUS_SRC_COLOR),
		SRC_ALPHA(GL_SRC_ALPHA),
		ONE_MINUS_SRC_ALPHA(GL_ONE_MINUS_SRC_ALPHA),
		DST_ALPHA(GL_DST_ALPHA),
		ONE_MINUS_DST_ALPHA(GL_ONE_MINUS_DST_ALPHA),
		DST_COLOR(GL_DST_COLOR),
		ONE_MINUS_DST_COLOR(GL_ONE_MINUS_DST_COLOR),
		SRC_ALPHA_SATURATE(GL_SRC_ALPHA_SATURATE);
	}

	companion object {
		val DEFAULT = BlendFunc()
		val MULTIPLY_WITH_ALPHA = BlendFunc(Func.SRC_ALPHA, Func.ONE_MINUS_SRC_ALPHA)
		val ADDITIVE = BlendFunc(Func.ONE, Func.ONE)

		val ONLY_ALPHA = BlendFunc(
			Func.ZERO,
			Func.ONE,
			Func.ONE,
			Func.ZERO
		)

		val ONLY_BLEND_ALPHA = BlendFunc(
			Func.ZERO,
			Func.ONE,
			Func.ONE,
			Func.ONE
		)

		val ONLY_COLOR = BlendFunc(
			Func.ONE,
			Func.ZERO,
			Func.ZERO,
			Func.ONE
		)

		val MULTIPLY_BY_SRC = BlendFunc(
			Func.ZERO,
			Func.SRC_COLOR,
			Func.ONE,
			Func.ZERO
		)
	}
}

interface GLCleanable : Cleaner.Cleanable {
	/**
	 * Выставляет флаг на то, что объект был удалён вручную и вызывает clean()
	 */
	fun cleanManual()
}

interface GLStreamBuilderList {
	val small: StreamVertexBuilder
}

@Suppress("PropertyName", "unused")
class GLStateTracker {
	private fun isMe(state: GLStateTracker?) {
		if (state != null && state != this) {
			throw InvalidArgumentException("Provided object does not belong to $this state tracker (belongs to $state)")
		}
	}

	init {
		check(TRACKERS.get() == null) { "Already has state tracker existing at this thread!" }
		TRACKERS.set(this)
		// This line is critical for LWJGL's interoperation with GLFW's
		// OpenGL context, or any context that is managed externally.
		// LWJGL detects the context that is current in the current thread,
		// creates the GLCapabilities instance and makes the OpenGL
		// bindings available for use.
		GL.createCapabilities()
	}

	private val cleanerHits = ArrayList<() -> Unit>()

	private val cleaner = Cleaner.create(object : ThreadFactory {
		override fun newThread(r: Runnable): Thread {
			val thread = Thread(r, "OpenGL Object Cleaner@" + System.identityHashCode(this))
			thread.priority = 2
			return thread
		}
	})

	fun registerCleanable(ref: Any, fn: (Int) -> Unit, name: String, nativeRef: Int): GLCleanable {
		var cleanManual = false

		val cleanable = cleaner.register(ref) {
			if (!cleanManual && LOGGER.isTraceEnabled)
				LOGGER.trace("{} with ID {} was GC'd by JVM, without manually calling close()", name, nativeRef)

			if (isSameThread()) {
				fn(nativeRef)
				checkForGLError()
			} else {
				synchronized(cleanerHits) {
					cleanerHits.add {
						fn(nativeRef)
						checkForGLError()
					}
				}
			}
		}

		return object : GLCleanable {
			override fun cleanManual() {
				cleanManual = true
				clean()
			}

			override fun clean() = cleanable.clean()
		}
	}

	fun cleanup() {
		synchronized(cleanerHits) {
			for (lambda in cleanerHits) {
				lambda.invoke()
			}

			cleanerHits.clear()
		}
	}

	var blend by GLStateSwitchTracker(GL_BLEND)
	var scissor by GLStateSwitchTracker(GL_SCISSOR_TEST)

	var cull by GLStateSwitchTracker(GL_CULL_FACE)
	var cullMode by GLStateFuncTracker(::glCullFace, GL_BACK)

	var scissorRect by GLStateGenericTracker(ScissorRect(0, 0, 0, 0)) {
		// require(it.x >= 0) { "Invalid X ${it.x}"}
		// require(it.y >= 0) { "Invalid Y ${it.y}"}

		require(it.width >= 0) { "Invalid width ${it.width}"}
		require(it.height >= 0) { "Invalid height ${it.height}"}

		glScissor(it.x, it.y, it.width, it.height)
	}

	var depthTest by GLStateSwitchTracker(GL_DEPTH_TEST)

	var VBO: VertexBufferObject? = null
		set(value) {
			ensureSameThread()
			if (field === value) return
			isMe(value?.state)
			field = value

			if (value == null) {
				glBindBuffer(GL_ARRAY_BUFFER, 0)
				checkForGLError()
				return
			}

			if (!value.isArray) throw IllegalArgumentException("Provided buffer object is not of Array type")
			glBindBuffer(GL_ARRAY_BUFFER, value.pointer)
			checkForGLError()
		}

	var EBO: VertexBufferObject? = null
		set(value) {
			ensureSameThread()
			if (field === value) return
			isMe(value?.state)
			field = value

			if (value == null) {
				glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0)
				checkForGLError()
				return
			}

			if (!value.isElementArray) throw IllegalArgumentException("Provided buffer object is not of Array type")
			glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, value.pointer)
			checkForGLError()
		}

	var VAO: VertexArrayObject? = null
		set(value) {
			ensureSameThread()
			if (field === value) return
			isMe(value?.state)
			field = value

			if (value == null) {
				glBindVertexArray(0)
				checkForGLError()
				return
			}

			glBindVertexArray(value.pointer)
			checkForGLError()
		}

	var readFramebuffer: GLFrameBuffer? = null
		set(value) {
			ensureSameThread()
			if (field === value) return
			isMe(value?.state)
			field = value

			if (value == null) {
				glBindFramebuffer(GL_READ_FRAMEBUFFER, 0)
				checkForGLError()
				return
			}

			glBindFramebuffer(GL_READ_FRAMEBUFFER, value.pointer)
			checkForGLError()
		}

	var writeFramebuffer: GLFrameBuffer? = null
		set(value) {
			ensureSameThread()
			if (field === value) return
			isMe(value?.state)
			field = value

			if (value == null) {
				glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0)
				checkForGLError()
				return
			}

			glBindFramebuffer(GL_DRAW_FRAMEBUFFER, value.pointer)
			checkForGLError()
		}

	var framebuffer: GLFrameBuffer?
		get() {
			val readFramebuffer = readFramebuffer
			val writeFramebuffer = writeFramebuffer

			if (readFramebuffer == writeFramebuffer) {
				return writeFramebuffer
			}

			return null
		}
		set(value) {
			readFramebuffer = value
			writeFramebuffer = value
		}

	var program: GLShaderProgram? = null
		private set

	var activeTexture = 0
		set(value) {
			ensureSameThread()
			if (field == value) return
			require(value >= 0) { "Invalid texture block $value" }
			require(value < 80) { "Too big texture block index $value, OpenGL 4.6 guarantee only 80!" }
			field = value
			glActiveTexture(GL_TEXTURE0 + value)
			checkForGLError()
		}

	var texture2D: GLTexture2D? by TexturesTracker(80)

	var clearColor by GLStateGenericTracker<IStruct4f>(Color.WHITE) {
		val (r, g, b, a) = it
		glClearColor(r, g, b, a)
	}

	var blendFunc by GLStateGenericTracker(BlendFunc()) {
		glBlendFuncSeparate(it.sourceColor.enum, it.destinationColor.enum, it.sourceAlpha.enum, it.destinationAlpha.enum)
	}

	init {
		glActiveTexture(GL_TEXTURE0)
		checkForGLError()
	}

	val thread: Thread = Thread.currentThread()
	val tileRenderers = TileRenderers(this)

	fun ensureSameThread() {
		if (thread !== Thread.currentThread()) {
			throw IllegalAccessException("Trying to access $this outside of $thread!")
		}
	}

	fun isSameThread() = thread === Thread.currentThread()

	fun program(vararg shaders: GLShader): GLShaderProgram {
		return GLShaderProgram(this, *shaders)
	}

	fun newVBO(type: VBOType = VBOType.ARRAY): VertexBufferObject {
		return VertexBufferObject(this, type)
	}

	fun newEBO() = newVBO(VBOType.ELEMENT_ARRAY)
	fun newVAO() = VertexArrayObject(this)
	fun newTexture(name: String = "<unknown>") = GLTexture2D(this, name)

	private val named2DTextures = HashMap<String, GLTexture2D>()

	fun loadNamedTexture(path: String, memoryFormat: Int, fileFormat: Int): GLTexture2D {
		return named2DTextures.computeIfAbsent(path) {
			if (!Starbound.exists(path)) {
				throw FileNotFoundException("Unable to locate $path")
			}

			return@computeIfAbsent newTexture(path).upload(Starbound.readDirect(path), memoryFormat, fileFormat).generateMips()
		}
	}

	fun loadNamedTexture(path: String): GLTexture2D {
		return named2DTextures.computeIfAbsent(path) {
			if (!Starbound.exists(path)) {
				throw FileNotFoundException("Unable to locate $path")
			}

			return@computeIfAbsent newTexture(path).upload(Starbound.readDirect(path)).generateMips()
		}
	}

	private var loadedEmptyTexture = false
	private val missingTexturePath = "/assetmissing.png"

	fun loadNamedTextureSafe(path: String, memoryFormat: Int, fileFormat: Int): GLTexture2D {
		if (!loadedEmptyTexture) {
			loadedEmptyTexture = true
			named2DTextures[missingTexturePath] = newTexture(missingTexturePath).upload(Starbound.readDirect(missingTexturePath), memoryFormat, fileFormat).generateMips()
		}

		return named2DTextures.computeIfAbsent(path) {
			if (!Starbound.exists(path)) {
				LOGGER.error("Texture {} is missing! Falling back to {}", path, missingTexturePath)
				return@computeIfAbsent named2DTextures[missingTexturePath]!!
			}

			return@computeIfAbsent newTexture(path).upload(Starbound.readDirect(path), memoryFormat, fileFormat).generateMips()
		}
	}

	fun loadNamedTextureSafe(path: String): GLTexture2D {
		if (!loadedEmptyTexture) {
			loadedEmptyTexture = true
			named2DTextures[missingTexturePath] = newTexture(missingTexturePath).upload(Starbound.readDirect(missingTexturePath), GL_RGBA, GL_RGBA).generateMips()
		}

		return named2DTextures.computeIfAbsent(path) {
			if (!Starbound.exists(path)) {
				LOGGER.error("Texture {} is missing! Falling back to {}", path, missingTexturePath)
				return@computeIfAbsent named2DTextures[missingTexturePath]!!
			}

			return@computeIfAbsent newTexture(path).upload(Starbound.readDirect(path)).generateMips()
		}
	}

	fun bind(obj: VertexBufferObject): VertexBufferObject {
		if (obj.type == VBOType.ARRAY)
			VBO = obj
		else
			EBO = obj

		return obj
	}

	fun unbind(obj: VertexBufferObject): VertexBufferObject {
		if (obj.type == VBOType.ARRAY)
			if (obj == VBO)
				VBO = null
		else
			if (obj == EBO)
				EBO = null

		return obj
	}

	fun bind(obj: VertexArrayObject): VertexArrayObject {
		VAO = obj
		return obj
	}

	fun unbind(obj: VertexArrayObject): VertexArrayObject {
		if (obj == VAO)
			VAO = null

		return obj
	}

	fun use(obj: GLShaderProgram): GLShaderProgram {
		ensureSameThread()

		if (obj == program) {
			return obj
		}

		check(obj.linked) { "Program is not linked!" }

		program = obj
		glUseProgram(obj.pointer)
		checkForGLError()
		return obj
	}

	val shaderVertexTexture: GLTransformableProgram
	val shaderVertexTextureColor: GLTransformableColorableProgram

	init {
		val textureF = GLShader.internalFragment("shaders/fragment/texture.glsl")
		val textureColorF = GLShader.internalFragment("shaders/fragment/texture_color.glsl")
		val textureV = GLShader.internalVertex("shaders/vertex/texture.glsl")

		shaderVertexTexture = GLTransformableProgram(this, textureF, textureV)
		shaderVertexTextureColor = GLTransformableColorableProgram(this, textureColorF, textureV)

		textureF.unlink()
		textureColorF.unlink()
		textureV.unlink()
	}

	val programs = GLPrograms(this)

	val flat2DLines = object : GLStreamBuilderList {
		override val small by lazy {
			return@lazy StreamVertexBuilder(this@GLStateTracker, GLAttributeList.VEC2F, GeometryType.LINES, 1024)
		}
	}

	val flat2DTriangles = object : GLStreamBuilderList {
		override val small by lazy {
			return@lazy StreamVertexBuilder(this@GLStateTracker, GLAttributeList.VEC2F, GeometryType.TRIANGLES, 1024)
		}
	}

	val flat2DTexturedQuads = object : GLStreamBuilderList {
		override val small by lazy {
			return@lazy StreamVertexBuilder(this@GLStateTracker, GLAttributeList.VERTEX_TEXTURE, GeometryType.QUADS, 1024)
		}
	}

	val quadWireframe by lazy {
		StreamVertexBuilder(this, GLAttributeList.VEC2F, GeometryType.QUADS_AS_LINES_WIREFRAME, 16384)
	}

	val matrixStack = Matrix4fStack()
	val freeType = FreeType()

	val font = Font(this)

	inline fun quadWireframe(color: Color = Color.WHITE, lambda: (StreamVertexBuilder) -> Unit) {
		val builder = quadWireframe

		builder.begin()
		lambda.invoke(builder)
		builder.upload()

		programs.flat.use()
		programs.flat.color.set(color)
		programs.flat.transform.set(matrixStack.last)

		builder.draw(GL_LINES)
	}

	inline fun quadColor(lambda: (StreamVertexBuilder) -> Unit) {
		val builder = programs.flatColor.builder

		builder.begin()
		lambda.invoke(builder)
		builder.upload()

		programs.flatColor.use()
		programs.flatColor.transform.set(matrixStack.last)

		builder.draw(GL_TRIANGLES)
	}

	inline fun quadWireframe(value: AABB, color: Color = Color.WHITE, chain: (StreamVertexBuilder) -> Unit = {}) {
		quadWireframe(color) {
			it.quad(value.mins.x.toFloat(), value.mins.y.toFloat(), value.maxs.x.toFloat(), value.maxs.y.toFloat())
			chain(it)
		}
	}

	val box2dRenderer = Box2DRenderer(this)

	companion object {
		private val LOGGER = LogManager.getLogger(GLStateTracker::class.java)
		private val TRACKERS = ThreadLocal<GLStateTracker>()
	}
}