#pragma once

class DirHelper {

	static constexpr const char* NAME = "FAT32_DirH";

public:

	enum class CreateType {
		NONE,
		DIR,
		FILE
	};

	/**
	 * get (or allocate, if needed) a new DirEntry with the given name absolute name
	 * if the entry is allocated, it is UNTYPED
	 * name: e.g. /path1/path2/path3 or /path1/path2/file.txt
	 */
	static DirHandle getOrCreate(FS& fs, ClusterNr dirStartCluster, const std::string& absName, CreateType ct) {

		// determine the local name
		Split s = split(absName);

		{	// search for a matching existing entry
			DirIterator di(fs, dirStartCluster);
			while(true) {

				DirHandle h = di.nextUsable();
				if (!h.isValid()) {break;}

				// found a matching entry
				const std::string n = h.getName();
				if (n == s.first) {

					// are we done yet?
					if (s.hasMore()) {
						const ClusterNr subDirStartCluster = h.getFirstCluster();
						return getOrCreate(fs, subDirStartCluster, s.next, ct);
					} else {
						return h;
					}

				}
			}
		}

		// no matching entry found
		if (ct == CreateType::NONE) {return DirHandle::invalid();}

		{	// allocate a new DirEntry within the current directory

			DirIterator di(fs, dirStartCluster);
			DirHandle h = di.nextFree();
			h.setName(s.first);
			h.setSize(0);
			h.setFirstCluster(0);

			// if this is a sub-directory, allocate a new cluster for it
			if (s.hasMore() || ct == CreateType::DIR) {

				// allocate a cluster where the directory contents are to be stored
				ClusterNr freeCluster = fs.allocFreeCluster(0);
				h.setFirstCluster(freeCluster);
				h.setDirectory();
				fs.write(h);

				// ensure the new cluster is initialized with all zeros (this is also equal to an immediate END_OF_DIRECTORY marker in the beginning
				fs.zeroOutCluster(freeCluster);

				DirIterator di2(fs, freeCluster);

				// create the "." entry (pointer to current directory)
				DirHandle h2 = di2.next();
				h2.setDot(freeCluster);
				fs.write(h2);

				// create the ".." entry (pointer to parent directory)
				DirHandle h3 = di2.next();
				h3.setDotDot(dirStartCluster);
				fs.write(h3);

				// more path to process?
				if (s.hasMore()) {
					return getOrCreate(fs, freeCluster, s.next, ct);
				} else {
					return h;
				}

			} else {

				fs.write(h);
				return h;

			}

		}

	}

private:

	struct Split {

		std::string first;
		std::string next;

		Split(const std::string& first, const std::string& next) : first(first), next(next) {}

		bool hasMore() const {return !next.empty();}

	};

	/** split "/path1/path2/path3/file.txt" into "path1" and "path2/path3/file.txt" */
	static Split split(std::string absPath) {

		if (absPath[0] == '/') {
			absPath = absPath.substr(1);
		}

		std::size_t pos = absPath.find('/');
		if (pos == std::string::npos) {
			return Split(absPath, "");
		} else {
			return Split(absPath.substr(0, pos), absPath.substr(pos));
		}

	}

};