#pragma once

#include <c++11Helpers.h>
#include <cerrno>
#include <cstdio>
#include <exception>
#include <fuse.h>
#include <lockHelpers.h>
#include <shared_mutex>
#include <syslog.h>
#include <typeinfo>
#include <visibility.h>

class DLL_PUBLIC FuseAppBase {
public:
	FuseAppBase();
	SPECIAL_MEMBERS_DELETE(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 *);
	// NOLINTNEXTLINE(hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
	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) noexcept;
	virtual void beforeOperation();
	void log(int level, const char * message) const noexcept;
	void logf(int level, const char * fmt, ...) const noexcept __attribute__((__format__(__printf__, 3, 4)));
	virtual void vlogf(int level, const char * fmt, va_list) const noexcept
			__attribute__((__format__(__printf__, 3, 0)))
			= 0;

	mutable std::shared_mutex mutex;

protected:
	static FuseAppBase * fuseApp;

	template<bool Implemented, auto bfunc>
	constexpr static auto
	getInternalHelper()
	{
		if constexpr (Implemented) {
			return [](auto... a) {
				SharedLock(fuseApp->mutex);
				return (fuseApp->*bfunc)(a...);
			};
		}
		else {
			return nullptr;
		}
	}

	template<bool Implemented, auto bfunc>
	constexpr static auto
	getHelper()
	{
		if constexpr (Implemented) {
			return [](auto... a) {
				using Return = decltype((fuseApp->*bfunc)(a...));
				for (int t = 0;; ++t) {
					try {
						fuseApp->beforeOperation();
						SharedLock(fuseApp->mutex);
						return (fuseApp->*bfunc)(a...);
					}
					catch (const std::exception & ex) {
						if (t < 10) {
							if (Return rtn = fuseApp->onError(ex)) {
								return rtn;
							}
						}
						else {
							fuseApp->logf(
									LOG_ERR, "Retries expired with %s calling %s", ex.what(), typeid(bfunc).name());
							return static_cast<Return>(-EIO);
						}
					}
					catch (...) {
						fuseApp->logf(LOG_ERR, "Unknown exception calling %s", typeid(bfunc).name());
						return static_cast<Return>(-EIO);
					}
				}
			};
		}
		else {
			return nullptr;
		}
	}
};

template<typename FuseApp> class FuseAppBaseT : public FuseAppBase {
private:
public:
#define GetIntHelper(func) \
	getInternalHelper<!std::is_same_v<decltype(&FuseAppBase::func), decltype(&FuseApp::func)>, &FuseAppBase::func>()
#define GetHelper(func) \
	getHelper<!std::is_same_v<decltype(&FuseAppBase::func), decltype(&FuseApp::func)>, &FuseAppBase::func>()
	constexpr const static fuse_operations 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

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