#include "WorldRenderer.h"

#include <iostream>
#include <GL/glew.h>
#include <memory>
#include <assert.h>

#include "../window/Window.h"
#include "../window/Camera.h"
#include "../content/Content.h"
#include "../graphics/ChunksRenderer.h"
#include "../graphics/Mesh.h"
#include "../graphics/Atlas.h"
#include "../graphics/Shader.h"
#include "../graphics/Batch3D.h"
#include "../graphics/Texture.h"
#include "../graphics/LineBatch.h"
#include "../voxels/Chunks.h"
#include "../voxels/Chunk.h"
#include "../voxels/Block.h"
#include "../world/World.h"
#include "../world/Level.h"
#include "../world/LevelEvents.h"
#include "../objects/Player.h"
#include "../assets/Assets.h"
#include "../logic/PlayerController.h"
#include "../maths/FrustumCulling.h"
#include "../maths/voxmaths.h"
#include "../settings.h"
#include "../engine.h"
#include "../items/ItemDef.h"
#include "../items/ItemStack.h"
#include "../items/Inventory.h"
#include "LevelFrontend.h"
#include "graphics/Skybox.h"

using glm::vec3;
using glm::vec4;
using glm::mat4;

WorldRenderer::WorldRenderer(Engine* engine, LevelFrontend* frontend) 
	: engine(engine), 
	  level(frontend->getLevel()),
	  frustumCulling(new Frustum()),
	  lineBatch(new LineBatch()),
	  renderer(new ChunksRenderer(level, 
                frontend->getContentGfxCache(), 
                engine->getSettings())),
      batch3d(new Batch3D(4096)) {

	auto& settings = engine->getSettings();
	level->events->listen(EVT_CHUNK_HIDDEN, 
		[this](lvl_event_type type, Chunk* chunk) {
			renderer->unload(chunk);
		}
	);
	auto assets = engine->getAssets();
	skybox = new Skybox(settings.graphics.skyboxResolution, 
						assets->getShader("skybox_gen"));
}

WorldRenderer::~WorldRenderer() {
	delete skybox;
	delete lineBatch;
	delete renderer;
	delete frustumCulling;
}

bool WorldRenderer::drawChunk(size_t index,
							  Camera* camera, 
							  Shader* shader, 
							  bool culling){
	auto chunk = level->chunks->chunks[index];
	if (!chunk->isLighted()) {
		return false;
	}
	auto mesh = renderer->getOrRender(chunk.get());
	if (mesh == nullptr) {
		return false;
	}
	if (culling){
		vec3 min(chunk->x * CHUNK_W, 
				 chunk->bottom, 
				 chunk->z * CHUNK_D);
		vec3 max(chunk->x * CHUNK_W + CHUNK_W, 
				 chunk->top, 
				 chunk->z * CHUNK_D + CHUNK_D);

		if (!frustumCulling->IsBoxVisible(min, max)) return false;
	}
	vec3 coord = vec3(chunk->x*CHUNK_W+0.5f, 0.5f, chunk->z*CHUNK_D+0.5f);
	mat4 model = glm::translate(mat4(1.0f), coord);
	shader->uniformMatrix("u_model", model);
	mesh->draw();
	return true;
}

void WorldRenderer::drawChunks(Chunks* chunks, 
							   Camera* camera, 
							   Shader* shader) {
	std::vector<size_t> indices;
	for (size_t i = 0; i < chunks->volume; i++){
		if (chunks->chunks[i] == nullptr)
			continue;
		indices.push_back(i);
	}
	float px = camera->position.x / (float)CHUNK_W;
	float pz = camera->position.z / (float)CHUNK_D;
	std::sort(indices.begin(), indices.end(), [chunks, px, pz](size_t i, size_t j) {
		auto a = chunks->chunks[i];
		auto b = chunks->chunks[j];
		return ((a->x + 0.5f - px)*(a->x + 0.5f - px) + 
				(a->z + 0.5f - pz)*(a->z + 0.5f - pz)
				>
				(b->x + 0.5f - px)*(b->x + 0.5f - px) + 
				(b->z + 0.5f - pz)*(b->z + 0.5f - pz));
	});

	bool culling = engine->getSettings().graphics.frustumCulling;
	if (culling) {
		frustumCulling->update(camera->getProjView());
	}
	chunks->visible = 0;
	for (size_t i = 0; i < indices.size(); i++){
		chunks->visible += drawChunk(indices[i], camera, shader, culling);
	}
}


void WorldRenderer::draw(const GfxContext& pctx, Camera* camera, bool hudVisible){
    Window::clearDepth();
	EngineSettings& settings = engine->getSettings();
	skybox->refresh(pctx, level->world->daytime, 1.0f+fog*2.0f, 4);

	const Content* content = level->content;
	auto indices = content->getIndices();
	Assets* assets = engine->getAssets();
	Atlas* atlas = assets->getAtlas("blocks");
	Shader* shader = assets->getShader("main");

	const Viewport& viewport = pctx.getViewport();
	int displayWidth = viewport.getWidth();
	int displayHeight = viewport.getHeight();

	// Drawing background sky plane
	skybox->draw(pctx, camera, assets, level->getWorld()->daytime, fog);

	Shader* linesShader = assets->getShader("lines");
	{
		GfxContext ctx = pctx.sub();
		ctx.depthTest(true);
		ctx.cullFace(true);

		float fogFactor = 15.0f / ((float)settings.chunks.loadDistance-2);

		// Setting up main shader
		shader->use();
		shader->uniformMatrix("u_proj", camera->getProjection());
		shader->uniformMatrix("u_view", camera->getView());
		shader->uniform1f("u_gamma", settings.graphics.gamma);
		shader->uniform1f("u_fogFactor", fogFactor);
		shader->uniform1f("u_fogCurve", settings.graphics.fogCurve);
		shader->uniform3f("u_cameraPos", camera->position);
		shader->uniform1i("u_cubemap", 1);
		{
            auto player = level->player;
            auto inventory = player->getInventory();
            ItemStack& stack = inventory->getSlot(player->getChosenSlot());
            ItemDef* item = indices->getItemDef(stack.getItemId());
			assert(item != nullptr);
			float multiplier = 0.5f;
			shader->uniform3f("u_torchlightColor",  
					item->emission[0] / 15.0f * multiplier,
					item->emission[1] / 15.0f * multiplier,
					item->emission[2] / 15.0f * multiplier);
			shader->uniform1f("u_torchlightDistance", 6.0f);
		}

		// Binding main shader textures
		skybox->bind();
		atlas->getTexture()->bind();

		drawChunks(level->chunks, camera, shader);

		// Selected block
		if (PlayerController::selectedBlockId != -1 && hudVisible){
			blockid_t id = PlayerController::selectedBlockId;
			Block* block = indices->getBlockDef(id);
			assert(block != nullptr);
			const vec3 pos = PlayerController::selectedBlockPosition;
			const vec3 point = PlayerController::selectedPointPosition;
			const vec3 norm = PlayerController::selectedBlockNormal;
			AABB hitbox = block->hitbox;
			if (block->rotatable) {
				auto states = PlayerController::selectedBlockStates;
				block->rotations.variants[states].transform(hitbox);
			}

			const vec3 center = pos + hitbox.center();
			const vec3 size = hitbox.size();
			linesShader->use();
			linesShader->uniformMatrix("u_projview", camera->getProjView());
			lineBatch->lineWidth(2.0f);
			lineBatch->box(center, size + vec3(0.02), vec4(0.f, 0.f, 0.f, 0.5f));
			if (level->player->debug)
				lineBatch->line(point, point+norm*0.5f, vec4(1.0f, 0.0f, 1.0f, 1.0f));
			lineBatch->render();
		}
		skybox->unbind();
	}

	if (hudVisible && level->player->debug) {
		GfxContext ctx = pctx.sub();
		ctx.depthTest(true);

		linesShader->use();

		if (settings.debug.showChunkBorders){
			linesShader->uniformMatrix("u_projview", camera->getProjView());
			vec3 coord = level->player->camera->position;
			if (coord.x < 0) coord.x--;
			if (coord.z < 0) coord.z--;
			int cx = floordiv((int)coord.x, CHUNK_W);
			int cz = floordiv((int)coord.z, CHUNK_D);

			drawBorders(cx * CHUNK_W, 0, cz * CHUNK_D, 
					    (cx + 1) * CHUNK_W, CHUNK_H, (cz + 1) * CHUNK_D);
		}

		float length = 40.f;
		vec3 tsl = vec3(displayWidth/2, displayHeight/2, 0.f);
		glm::mat4 model(glm::translate(glm::mat4(1.f), tsl));
		linesShader->uniformMatrix("u_projview", glm::ortho(
				0.f, (float)displayWidth, 
				0.f, (float)displayHeight,
				-length, length) * model * glm::inverse(camera->rotation));

		ctx.depthTest(false);
		lineBatch->lineWidth(4.0f);
		lineBatch->line(0.f, 0.f, 0.f, length, 0.f, 0.f, 0.f, 0.f, 0.f, 1.f);
		lineBatch->line(0.f, 0.f, 0.f, 0.f, length, 0.f, 0.f, 0.f, 0.f, 1.f);
		lineBatch->line(0.f, 0.f, 0.f, 0.f, 0.f, length, 0.f, 0.f, 0.f, 1.f);
		lineBatch->render();

		ctx.depthTest(true);
		lineBatch->lineWidth(2.0f);
		lineBatch->line(0.f, 0.f, 0.f, length, 0.f, 0.f, 1.f, 0.f, 0.f, 1.f);
		lineBatch->line(0.f, 0.f, 0.f, 0.f, length, 0.f, 0.f, 1.f, 0.f, 1.f);
		lineBatch->line(0.f, 0.f, 0.f, 0.f, 0.f, length, 0.f, 0.f, 1.f, 1.f);
		lineBatch->render();
	}
}

void WorldRenderer::drawBorders(int sx, int sy, int sz, int ex, int ey, int ez) {
	int ww = ex-sx;
	int dd = ez-sz;
	/*corner*/ {
		lineBatch->line(sx, sy, sz,     
						sx, ey, sz, 0.8f, 0, 0.8f, 1);
		lineBatch->line(sx, sy, ez,     
						sx, ey, ez, 0.8f, 0, 0.8f, 1);
		lineBatch->line(ex, sy, sz,     
						ex, ey, sz, 0.8f, 0, 0.8f, 1);
		lineBatch->line(ex, sy, ez,     
						ex, ey, ez, 0.8f, 0, 0.8f, 1);
	}
	for (int i = 2; i < ww; i+=2) {
		lineBatch->line(sx + i, sy, sz,     
						sx + i, ey, sz, 0, 0, 0.8f, 1);
		lineBatch->line(sx + i, sy, ez,     
						sx + i, ey, ez, 0, 0, 0.8f, 1);
	}
	for (int i = 2; i < dd; i+=2) {
		lineBatch->line(sx, sy, sz + i, 
						sx, ey, sz + i, 0.8f, 0, 0, 1);
		lineBatch->line(ex, sy, sz + i, 
						ex, ey, sz + i, 0.8f, 0, 0, 1);
	}
	for (int i = sy; i < ey; i+=2){
		lineBatch->line(sx, i, sz,
						sx, i, ez, 0, 0.8f, 0, 1);
		lineBatch->line(sx, i, ez,
						ex, i, ez, 0, 0.8f, 0, 1);
		lineBatch->line(ex, i, ez,
						ex, i, sz, 0, 0.8f, 0, 1);
		lineBatch->line(ex, i, sz,
						sx, i, sz, 0, 0.8f, 0, 1);
	}
	lineBatch->render();
}

float WorldRenderer::fog = 0.0f;