#ifndef FUSEAPP_H
#define FUSEAPP_H

#include <fuse.h>
#include <typeinfo>
#include <exception>
#include <stdio.h>
#include <errno.h>
#include <syslog.h>
#include <visibility.h>
#include <buffer.h>
#include <shared_mutex>
#include <lockHelpers.h>

class DLL_PUBLIC FuseAppBase {
	public:
		FuseAppBase();
		virtual ~FuseAppBase();

		virtual void * init (struct fuse_conn_info * info, struct fuse_config * cfg);
		virtual int access(const char *, int);
		virtual int chmod(const char *, mode_t, struct fuse_file_info *);
		virtual int chown(const char *, uid_t, gid_t, struct fuse_file_info *);
		virtual int create(const char *, mode_t, struct fuse_file_info *);
		virtual int getattr(const char *, struct stat *, struct fuse_file_info *);
		virtual int flush(const char *, struct fuse_file_info *);
		virtual int fsync(const char *, int, struct fuse_file_info *);
		virtual int fsyncdir(const char *, int, struct fuse_file_info *);
		virtual int truncate(const char *, off_t, struct fuse_file_info *);
		virtual int getxattr(const char *, const char *, char *, size_t);
		virtual int link(const char *, const char *);
		virtual int listxattr(const char *, char *, size_t);
		virtual int mkdir(const char *, mode_t);
		virtual int mknod(const char *, mode_t, dev_t);
		virtual int open(const char *, struct fuse_file_info *);
		virtual int opendir(const char *, struct fuse_file_info *);
		virtual int read(const char *, char *, size_t, off_t, struct fuse_file_info *);
		virtual int readdir(const char *, void *, fuse_fill_dir_t, off_t, struct fuse_file_info *, enum fuse_readdir_flags);
		virtual int readlink(const char *, char *, size_t);
		virtual int release(const char *, struct fuse_file_info *);
		virtual int releasedir(const char *, struct fuse_file_info *);
		virtual int removexattr(const char *, const char *);
		virtual int rename(const char *, const char *, unsigned int);
		virtual int rmdir(const char *);
		virtual int setxattr(const char *, const char *, const char *, size_t, int);
		virtual int statfs(const char *, struct statvfs *);
		virtual int symlink(const char *, const char *);
		virtual int unlink(const char *);
		virtual int write(const char *, const char *, size_t, off_t, struct fuse_file_info *);
		virtual int lock(const char *, struct fuse_file_info *, int cmd, struct flock *);
		virtual int utimens(const char *, const struct timespec tv[2], struct fuse_file_info *);
		virtual int bmap(const char *, size_t blocksize, uint64_t *idx);
		virtual int ioctl(const char *, unsigned int cmd, void *arg, struct fuse_file_info *, unsigned int flags, void * data);
		virtual int poll(const char *, struct fuse_file_info *, struct fuse_pollhandle *, unsigned *);
		virtual int write_buf(const char *, struct fuse_bufvec *buf, off_t off, struct fuse_file_info *);
		virtual int read_buf(const char *, struct fuse_bufvec **bufp, size_t size, off_t off, struct fuse_file_info *);
		virtual int flock(const char *, struct fuse_file_info *, int op);
		virtual int fallocate(const char *, int, off_t, off_t, struct fuse_file_info *);
		virtual ssize_t copy_file_range(const char *, struct fuse_file_info *, off_t, const char *, struct fuse_file_info *, off_t, size_t, int);
		virtual off_t lseek(const char *, off_t off, int whence, struct fuse_file_info *);
		virtual int onError(const std::exception & err) throw();
		virtual void beforeOperation();
		void log(int level, const char * message) const throw();
		void logf(int level, const char * fmt, ...) const throw() __attribute__ ((__format__ (__printf__, 3, 4)));
		virtual void vlogf(int level, const char * fmt, va_list) const throw() __attribute__ ((__format__ (__printf__, 3, 0))) = 0;

		mutable std::shared_mutex _lock;
	protected:
		static FuseAppBase * fuseApp;
};

template <typename FuseApp>
class FuseAppBaseT : public FuseAppBase {
	public:
#define GetIntHelper(func) getInternalHelper<decltype(&FuseAppBase::func), decltype(&FuseApp::func), &FuseAppBase::func>(&FuseAppBase::func)
#define GetHelper(func) getHelper<decltype(&FuseAppBase::func), decltype(&FuseApp::func), &FuseAppBase::func>(&FuseAppBase::func)
		FuseAppBaseT() : operations({
				GetHelper(getattr),
				GetHelper(readlink),
				GetHelper(mknod),
				GetHelper(mkdir),
				GetHelper(unlink),
				GetHelper(rmdir),
				GetHelper(symlink),
				GetHelper(rename),
				GetHelper(link),
				GetHelper(chmod),
				GetHelper(chown),
				GetHelper(truncate),
				GetHelper(open),
				GetHelper(read),
				GetHelper(write),
				GetHelper(statfs),
				GetHelper(flush),
				GetHelper(release),
				GetHelper(fsync),
				GetHelper(setxattr),
				GetHelper(getxattr),
				GetHelper(listxattr),
				GetHelper(removexattr),
				GetHelper(opendir),
				GetHelper(readdir),
				GetHelper(releasedir),
				GetHelper(fsyncdir),
				GetIntHelper(init),
				nullptr, //fuseDestroy
				GetHelper(access),
				GetHelper(create),
				GetHelper(lock),
				GetHelper(utimens),
				GetHelper(bmap),
				GetHelper(ioctl),
				GetHelper(poll),
				GetHelper(write_buf),
				GetHelper(read_buf),
				GetHelper(flock),
				GetHelper(fallocate),
				GetHelper(copy_file_range),
				GetHelper(lseek),
			})
		{
		}
#undef GetHelper
#undef GetIntHelper

		const struct fuse_operations operations;

	private:
		template <typename BFunc, typename IFunc, BFunc bfunc, typename Rtn, typename ... Args>
		constexpr static auto getInternalHelper(Rtn(FuseAppBase::*)(Args...)) -> Rtn(*)(Args...)
		{
			if constexpr (!std::is_same<BFunc, IFunc>::value) {
				return [](Args ... a) {
					return (fuseApp->*bfunc)(a...);
				};
			}
			return nullptr;
		}
		template <typename BFunc, typename IFunc, BFunc bfunc, typename Rtn, typename ... Args>
		constexpr static auto getHelper(Rtn(FuseAppBase::*)(Args...)) -> Rtn(*)(Args...)
		{
			if constexpr (!std::is_same<BFunc, IFunc>::value) {
				return [](Args ... a) -> Rtn {
					for (int t = 0; ; ++t) {
						try {
							fuseApp->beforeOperation();
							SharedLock(fuseApp->_lock);
							return (fuseApp->*bfunc)(a...);
						}
						catch (const std::exception & ex) {
							if (t < 10) {
								if (int rtn = fuseApp->onError(ex)) {
									return rtn;
								}
							}
							else {
								fuseApp->logf(LOG_ERR, "Retries expired with %s calling %s", ex.what(), typeid(bfunc).name());
								return -EIO;
							}
						}
						catch (...) {
							fuseApp->logf(LOG_ERR, "Unknown exception calling %s", typeid(bfunc).name());
							return -EIO;
						}
					}
				};
			}
			return nullptr;
		}

	protected:
		template <typename Func, Func f, typename ... Args>
		static int internalHelper(Args ... a)
		{
			return (fuseApp->*f)(a...);
		}
};

#endif