BansheeEngine/BansheeEngine/Include/BsGUIInputTool.h

#pragma once

#include "BsPrerequisites.h"
#include "BsTextSprite.h"

namespace BansheeEngine
{
	/**
	 * @brief	Represents a single line of text used by the input tools.
	 */
	class BS_EXPORT GUIInputLineDesc
	{
	public:
		/**
		 * @brief	Constructs a new input line description.
		 *
		 * @param	startChar		Index of the first character on the line.
		 * @param	endChar			Index of the last character on the line.
		 * @param	lineHeight		Height of the line in pixels.
		 * @param	lineYStart		Vertical offset from the top of the text to the start of this line (0 for first line usually)
		 * @param	includesNewLine	True if the lines end character is a newline character.
		 */
		GUIInputLineDesc(UINT32 startChar, UINT32 endChar, UINT32 lineHeight, INT32 lineYStart, bool includesNewline);

		/**
		 * @brief	Returns index of the last character on the line. If lines contains a newline character it will be returned
		 *			unless you set "includeNewLine" to false, in which case the next end-most character is returned.
		 *			(If newline is the only character on the line, it's index will still be returned).
		 */
		UINT32 getEndChar(bool includeNewline = true) const;

		/**
		 * @brief	Returns index of the first character on the line.
		 */
		UINT32 getStartChar() const { return mStartChar; }

		/**
		 * @brief	Returns line height in pixels.
		 */
		UINT32 getLineHeight() const { return mLineHeight; }

		/**
		 * @brief	Returns vertical offset from the top of the text to the start of this line (0 for first line usually).
		 */
		INT32 getLineYStart() const { return mLineYStart; }

		/**
		 * @brief	Checks is the specified character index a newline. Character index is a global character index,
		 *			not relative to the start character index of this line. If the index is out of range of this line
		 *			character indices, it will always return false.
		 */
		bool isNewline(UINT32 charIdx) const;

		/**
		 * @brief	Returns true if the last character on this line is a newline.
		 */
		bool hasNewlineChar() const { return mIncludesNewline; }

	private:
		UINT32 mStartChar;
		UINT32 mEndChar;
		UINT32 mLineHeight;
		INT32 mLineYStart;
		bool mIncludesNewline;
	};

	class BS_EXPORT GUIInputTool
	{
	public:
		GUIInputTool();
		~GUIInputTool();

		/**
		 * @brief	Updates the input tool with new text descriptor and parent GUI element. These
		 *			values will be used for all further calculations.
		 */
		void updateText(const GUIElement* element, const TEXT_SPRITE_DESC& textDesc);
	protected:
		/**
		 * @brief	Returns text offset relative to parent widget.
		 */
		Vector2I getTextOffset() const;

		/**
		 * @brief	Returns number of lines in the current text string.
		 */
		UINT32 getNumLines() const { return (UINT32)mLineDescs.size(); }

		/**
		 * @brief	Returns descriptor for a line with the specified index.
		 */
		const GUIInputLineDesc& getLineDesc(UINT32 lineIdx) const { return mLineDescs.at(lineIdx); }

		/**
		 * @brief	Returns index of a line containing the specified character.
		 *
		 * @param	charIdx					Index of the character to look for.
		 * @param	newlineCountsOnNextLine	If true, newline characters will return the next line
		 *									and not the line they're actually on.
		 */
		UINT32 getLineForChar(UINT32 charIdx, bool newlineCountsOnNextLine = false) const;

		/**
		 * @brief	Returns a rectangle containing position and size of the character with the provided
		 *			index, relative to parent widget.
		 */
		Rect2I getCharRect(UINT32 charIdx) const;

		/**
		 * @brief	Returns a rectangle containing position and size of the character with the provided
		 *			index, relative to parent element.
		 */
		Rect2I getLocalCharRect(UINT32 charIdx) const;

		/**
		 * @brief	Returns character index nearest to the specified position. Position should be relative
		 *			to parent widget.
		 */
		INT32 getCharIdxAtPos(const Vector2I& pos) const;

		/**
		 * @brief	Returns true if the currently set text desctiptor is valid (has any characters).
		 */
		bool isDescValid() const;

		/**
		 * @brief	Gets a character index after the input index. Input index represents the empty areas between the characters. 
		 *			Newline counts as a character. (e.g. 0 is before the first character, 1 is after the first character but before 
		 *			the second, etc.)
		 * 			
		 * @note	This can return an out of range character index, in case the input index is specified after the last character.
		 */
		UINT32 getCharIdxAtInputIdx(UINT32 inputIdx) const;

		/**
		 * @brief	Checks is the specified character index a newline.
		 */
		bool isNewlineChar(UINT32 charIdx) const;

		/**
		 * @brief	Checks is the character after the specified input index a newline.
		 *
		 * @see		getCharIdxAtInputIdx
		 */
		bool isNewline(UINT32 inputIdx) const;

	protected:
		const GUIElement* mElement;

		Vector2* mQuads;
		UINT32 mNumQuads;

		TEXT_SPRITE_DESC mTextDesc;

		Vector<GUIInputLineDesc> mLineDescs;
	};
}