/**
 * @file llscrollbar.h
 * @brief Scrollbar UI widget
 *
 * $LicenseInfo:firstyear=2001&license=viewergpl$
 *
 * Copyright (c) 2001-2009, Linden Research, Inc.
 *
 * Second Life Viewer Source Code
 * The source code in this file ("Source Code") is provided by Linden Lab
 * to you under the terms of the GNU General Public License, version 2.0
 * ("GPL"), unless you have obtained a separate licensing agreement
 * ("Other License"), formally executed by you and Linden Lab.  Terms of
 * the GPL can be found in doc/GPL-license.txt in this distribution, or
 * online at http://secondlifegrid.net/programs/open_source/licensing/gplv2
 *
 * There are special exceptions to the terms and conditions of the GPL as
 * it is applied to this Source Code. View the full text of the exception
 * in the file doc/FLOSS-exception.txt in this software distribution, or
 * online at
 * http://secondlifegrid.net/programs/open_source/licensing/flossexception
 *
 * By copying, modifying or distributing this software, you acknowledge
 * that you have read and understood your obligations described above,
 * and agree to abide by those obligations.
 *
 * ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO
 * WARRANTIES, EXPRESS, IMPLIED OR OTHERWISE, REGARDING ITS ACCURACY,
 * COMPLETENESS OR PERFORMANCE.
 * $/LicenseInfo$
 */

#ifndef LL_SCROLLBAR_H
#define LL_SCROLLBAR_H

#include "llcolor4.h"
#include "lluictrl.h"

constexpr S32 SCROLLBAR_SIZE = 16;

class LLScrollbar : public LLUICtrl
{
public:
	enum ORIENTATION { HORIZONTAL, VERTICAL };

	LLScrollbar(const std::string& name, LLRect rect, ORIENTATION orientation,
				S32 doc_size, S32 doc_pos, S32 page_size,
				void (*change_callback)(S32, LLScrollbar*, void*),
				void* callback_user_data = NULL, S32 step_size = 1);

	~LLScrollbar() override;

	void setValue(const LLSD& value) override;

	// Overrides from LLView
	bool handleKeyHere(KEY key, MASK mask) override;
	bool handleMouseDown(S32 x, S32 y, MASK mask) override;
	bool handleMouseUp(S32 x, S32 y, MASK mask) override;
	bool handleHover(S32 x, S32 y, MASK mask) override;
	bool handleScrollWheel(S32 x, S32 y, S32 clicks) override;
	bool handleDragAndDrop(S32 x, S32 y, MASK mask, bool drop,
						   EDragAndDropType cargo_type,
						   void* cargo_data, EAcceptance* accept,
						   std::string& tooltip_msg) override;

	void reshape(S32 width, S32 height, bool call_from_parent = true) override;

	void draw() override;

	// How long the "document" is.
	void setDocSize(S32 size);
	LL_INLINE S32 getDocSize() const					{ return mDocSize; }

	// How many "lines" the "document" has scrolled.
	// 0 <= DocPos <= DocSize - DocVisibile
	void setDocPos(S32 pos, bool update_thumb = true);
	S32 getDocPos() const								{ return mDocPos; }

	// Setting both at once.
	void setDocParams(S32 size, S32 pos);

	// How many "lines" of the "document" is can appear on a page.
	void setPageSize(S32 page_size);
	LL_INLINE S32 getPageSize() const					{ return mPageSize; }

	// The farthest the document can be scrolled (top of the last page).
	LL_INLINE S32 getDocPosMax() const					{ return llmax(0, mDocSize - mPageSize); }
	void pageUp(S32 overlap);
	void pageDown(S32 overlap);

	LL_INLINE bool isAtBeginning()						{ return mDocPos == 0; }
	LL_INLINE bool isAtEnd()							{ return mDocPos == getDocPosMax(); }

	static void onLineUpBtnPressed(void* userdata);
	static void onLineDownBtnPressed(void* userdata);

	LL_INLINE void setTrackColor(const LLColor4& c)		{ mTrackColor = c; }
	LL_INLINE void setThumbColor(const LLColor4& c)		{ mThumbColor = c; }
	LL_INLINE void setHighlightColor(const LLColor4& c)	{ mHighlightColor = c; }
	LL_INLINE void setShadowColor(const LLColor4& c)	{ mShadowColor = c; }

	LL_INLINE void setOnScrollEndCallback(void (*callback)(void*), void* data)
	{
		mOnScrollEndCallback = callback;
		mOnScrollEndData = data;
	}

private:
	void updateThumbRect();
	void changeLine(S32 delta, bool update_thumb);

private:
	void				(*mChangeCallback)(S32 new_pos, LLScrollbar* self,
										   void* userdata);
	void*				mCallbackUserData;

	void				(*mOnScrollEndCallback)(void*);
	void*				mOnScrollEndData;

	const ORIENTATION	mOrientation;

	// Size of the document that the scrollbar is modeling. Units depend on the
	// user. 0 <= mDocSize.
	S32					mDocSize;

	// Position within the doc that the scrollbar is modeling, in "lines" (user
	// size)
	S32					mDocPos;
	// Maximum number of lines that can be seen at one time.
	S32					mPageSize;

	S32					mStepSize;

	LLRect				mThumbRect;
	S32					mDragStartX;
	S32					mDragStartY;
	F32					mHoverGlowStrength;
	F32					mCurGlowStrength;

	LLRect				mOrigRect;
	S32					mLastDelta;

	LLColor4			mTrackColor;
	LLColor4			mThumbColor;
	LLColor4			mFocusColor;
	LLColor4			mHighlightColor;
	LLColor4			mShadowColor;

	bool				mDocChanged;
};

#endif  // LL_SCROLLBAR_H