#ifndef OBJPOOL_H
#define OBJPOOL_H

#include <vector>
#include "../../../geo/Triangle3.h"
#include <unordered_map>

#include "OBJReader.h"
#include "Obstacle3.h"

// LINUX ONLY
//#include <dirent.h>
//#include <stdio.h>
#include <experimental/filesystem>


namespace Ray3D {

	/**
	 * load several named 3D models for quick re-use
	 */
	class OBJPool {

	private:

		/** singleton */
		OBJPool() {;}

		bool initDone = false;
		std::unordered_map<std::string, Obstacle3D> cache;

	public:

		/** singleton access */
		static OBJPool& get() {
			static OBJPool instance;
			return instance;
		}

		/** data folder */
		void init(const std::string& folder) {

			initDone = true;

			// LINUX ONLY!
			//DIR* d = opendir(folder.c_str());
			//if (!d) {throw Exception("OBJPool: folder not found: " + folder);}
			std::experimental::filesystem::path d(folder);
			if (!std::experimental::filesystem::exists(d)) {
				throw Exception("OBJPool: folder not found: " + folder);
			}

			//struct dirent *dir;
			//while ((dir = readdir(d)) != NULL) {
			for (std::experimental::filesystem::directory_entry entry : std::experimental::filesystem::directory_iterator(d)) {
				//const std::string absFile = folder + "/" + dir->d_name;
				const std::string absFile = entry.path().native();
				if (endsWith(absFile, ".obj")) {
					//std::string name = std::string(dir->d_name);
					std::string name = entry.path().filename();
					name = name.substr(0, name.length() - 4);	// without extension
					load(absFile, name);
				}
			}
			//closedir(d);

		}

		/** get all triangles for the given object (if known) */
		const Obstacle3D& getObject(const std::string& name) {

			// ensure the cache is initialized
			if (!initDone) {
				throw Exception("OBJPool: not initialized. call init(folder) first");
			}

			static Obstacle3D empty;

			// find the entry
			const auto& it = cache.find(name);
			if (it == cache.end()) {return empty;}
			return it->second;

		}

	private:

		inline bool endsWith(std::string const & value, std::string const & ending) {
			if (ending.size() > value.size()) return false;
			return std::equal(ending.rbegin(), ending.rend(), value.rbegin());
		}

		/** load the given .obj file into the cache */
		void load(const std::string& absName, const std::string& name) {

			OBJReader reader;
			reader.readFile(absName);
			//reader.readFile("/mnt/vm/paper/diss/code/IndoorMap/res/mdl/" + file + ".obj");	// todo

			// create triangles
			Obstacle3D obs;
			for (const OBJReader::Object& obj : reader.getData().objects) {
				for (const OBJReader::Face& face : obj.faces) {
					const Triangle3 tria(face.vnt[0].vertex, face.vnt[1].vertex, face.vnt[2].vertex);
					obs.triangles.push_back(tria);
				}
			}

			// store
			cache[name] = obs;

		}

	};

}

#endif // OBJPOOL_H