#include "ehs/io/FileMonitor_UNX.h"
#include "ehs/Log.h"

#include <sys/inotify.h>
#include <cerrno>
#include <unistd.h>
#include <fcntl.h>

#define BUF_LEN (1024 * (sizeof(inotify_event) + 16))

namespace ehs
{
	FileMonitor::~FileMonitor()
	{
		inotify_rm_watch( hdl, wd);
		close(hdl);
	}

	FileMonitor::FileMonitor()
		: hdl(-1), wd(-1)
	{
	}

	FileMonitor::FileMonitor(Str_8 filePath)
		: BaseFileMonitor((Str_8&&)filePath), hdl(-1), wd(-1)
	{
		FileMonitor::Initialize();
	}

	FileMonitor::FileMonitor(FileMonitor&& fm) noexcept
		: BaseFileMonitor((BaseFileMonitor&&)fm), hdl(fm.hdl), wd(fm.wd)
	{
		fm.hdl = -1;
		fm.wd = -1;
	}

	FileMonitor::FileMonitor(const FileMonitor& fm)
		: BaseFileMonitor(fm), hdl(-1), wd(-1)
	{
		FileMonitor::Initialize();
	}

	FileMonitor& FileMonitor::operator=(FileMonitor&& fm) noexcept
	{
		if (this == &fm)
			return *this;

		Release();

		BaseFileMonitor::operator=((BaseFileMonitor&&)fm);

		hdl = fm.hdl;
		wd = fm.wd;

		fm.hdl = -1;
		fm.wd = -1;

		return *this;
	}

	FileMonitor& FileMonitor::operator=(const FileMonitor& fm)
	{
		if (this == &fm)
			return *this;

		Release();

		BaseFileMonitor::operator=(fm);

		hdl = -1;
		wd = -1;

		Initialize();

		return *this;
	}

	void FileMonitor::Initialize()
	{
		if (!IsValid() || IsInitialized())
			return;

		hdl = inotify_init();
		if (hdl < 0)
		{
			EHS_LOG_INT("Error", 0, "Failed to initialize inotify.");
			return;
		}

		int flags = fcntl(hdl, F_GETFL, 0);
		if (flags == -1)
		{
			EHS_LOG_INT("Error", 1, "Failed to retrieve flags with error #" + Str_8::FromNum(errno) + ".");
			return;
		}

		flags |= O_NONBLOCK;

		if (fcntl(hdl, F_SETFL, flags) == -1)
		{
			EHS_LOG_INT("Error", 2, "Failed to set flags with error #" + Str_8::FromNum(errno) + ".");
			return;
		}

		wd = inotify_add_watch( hdl, filePath, IN_MODIFY | IN_DELETE_SELF | IN_MOVE_SELF | IN_ACCESS);
		if (wd < 0)
		{
			EHS_LOG_INT("Error", 3, "Failed to add watch.");
			close(hdl);
			hdl = -1;
			return;
		}
	}

	void FileMonitor::Release()
	{
		if (!IsValid() || !IsInitialized())
			return;

		inotify_rm_watch( hdl, wd);
		wd = -1;

		close(hdl);
		hdl = -1;
	}

	UInt_8 FileMonitor::Poll()
	{
		UInt_8 mask = EHS_FE_NONE;

		if (!IsValid() || !IsInitialized())
			return mask;

		Byte buffer[BUF_LEN];
		SInt_64 length = read(hdl, buffer, BUF_LEN);
		if (length < 0)
		{
			UInt_8 code = errno;
			if (code != EWOULDBLOCK)
				EHS_LOG_INT("Error", 0, "Failed to read with error #" + Str_8::FromNum(code) + ".");

			return mask;
		}

		UInt_64 i = 0;
		while (i < length)
		{
			inotify_event *event = (inotify_event*)&buffer[i];
			if (event->mask & IN_MODIFY)
				mask |= EHS_FE_MODIFIED;

			if (event->mask & IN_DELETE_SELF)
				mask |= EHS_FE_DELETED;

			if (event->mask & IN_MOVE_SELF)
				mask |= EHS_FE_MOVED;

			if (event->mask & IN_ACCESS)
				mask |= EHS_FE_OPENED;

			i += sizeof(inotify_event) + event->len;
		}

		if (mask & EHS_FE_DELETED || mask & EHS_FE_MOVED)
			Release();

		return mask;
	}

	bool FileMonitor::IsInitialized() const
	{
		return hdl >= 0 && wd >= 0;
	}
}