/* Copyright (C) 2015 Wildfire Games.
 * This file is part of 0 A.D.
 *
 * 0 A.D. is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * 0 A.D. is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "precompiled.h"

#include "GUITooltip.h"

#include "CGUI.h"
#include "GUIutil.h"
#include "IGUIObject.h"

#include "lib/timer.h"
#include "ps/CLogger.h"

/*
	Tooltips:
	When holding the mouse stationary over an object for some amount of time,
	the tooltip is displayed. If the mouse moves off that object, the tooltip
	disappears. If the mouse re-enters an object within a short time, the new
	tooltip is displayed immediately. (This lets you run the mouse across a
	series of buttons, without waiting ages for the text to pop up every time.)

	See Visual Studio's toolbar buttons for an example.


	Implemented as a state machine:

	(where "*" lines are checked constantly, and "<" lines are handled
	on entry to that state)

	IN MOTION
	* If the mouse stops, check whether it should have a tooltip and move to
	  'STATIONARY, NO TOOLTIP' or 'STATIONARY, TOOLIP'
	* If the mouse enters an object with a tooltip delay of 0, switch to 'SHOWING'

	STATIONARY, NO TOOLTIP
	* If the mouse moves, switch to 'IN MOTION'

	STATIONARY, TOOLTIP
	< Set target time = now + tooltip time
	* If the mouse moves, switch to 'IN MOTION'
	* If now > target time, switch to 'SHOWING'

	SHOWING
	< Start displaying the tooltip
	* If the mouse leaves the object, check whether the new object has a tooltip
	  and switch to 'SHOWING' or 'COOLING'

	COOLING  (since I can't think of a better name)
	< Stop displaying the tooltip
	< Set target time = now + cooldown time
	* If the mouse has moved and is over a tooltipped object, switch to 'SHOWING'
	* If now > target time, switch to 'STATIONARY, NO TOOLTIP'
*/

enum
{
	ST_IN_MOTION,
	ST_STATIONARY_NO_TOOLTIP,
	ST_STATIONARY_TOOLTIP,
	ST_SHOWING,
	ST_COOLING
};

GUITooltip::GUITooltip()
: m_State(ST_IN_MOTION), m_PreviousObject(NULL), m_PreviousTooltipName()
{
}

const double CooldownTime = 0.25; // TODO: Don't hard-code this value

bool GUITooltip::GetTooltip(IGUIObject* obj, CStr& style)
{
	if (obj && obj->SettingExists("_icon_tooltip_style") && obj->MouseOverIcon())
	{
		// Special code to handle icon tooltips in text objects
		if (GUI<CStr>::GetSetting(obj, "_icon_tooltip_style", style) == PSRETURN_OK)
		{
			// Check if icon tooltip text exists
			CStrW text;
			if (GUI<CStrW>::GetSetting(obj, "_icon_tooltip", text) == PSRETURN_OK)
			{
				if (text.empty())
				{
					// No tooltip
					return false;
				}

				if (style.empty())
				{
					// Text, but no style - use default
					style = "default";
				}

				m_IsIconTooltip = true;
				return true;
			}
		}
	}
	else if (obj && obj->SettingExists("tooltip_style")
		&& GUI<CStr>::GetSetting(obj, "tooltip_style", style) == PSRETURN_OK)
	{
		CStrW text;
		if (GUI<CStrW>::GetSetting(obj, "tooltip", text) == PSRETURN_OK)
		{
			if (text.empty())
			{
				// No tooltip
				return false;
			}

			if (style.empty())
			{
				// Text, but no style - use default
				style = "default";
			}

			m_IsIconTooltip = false;
			return true;
		}
	}

	// Failed while retrieving tooltip_style or tooltip
	return false;
}

void GUITooltip::ShowTooltip(IGUIObject* obj, const CPos& pos, const CStr& style, CGUI* gui)
{
	ENSURE(obj);

	// Ignore attempts to use tooltip ""
	if (style.empty())
		return;

	// Get the object referenced by 'tooltip_style'
	IGUIObject* tooltipobj = gui->FindObjectByName("__tooltip_"+style);
	if (!tooltipobj)
	{
		LOGERROR("Cannot find tooltip named '%s'", style.c_str());
		return;
	}

	IGUIObject* usedobj = tooltipobj; // object actually used to display the tooltip in

	CStr usedObjectName;
	if (GUI<CStr>::GetSetting(tooltipobj, "use_object", usedObjectName) == PSRETURN_OK
		&& !usedObjectName.empty())
	{
		usedobj = gui->FindObjectByName(usedObjectName);
		if (!usedobj)
		{
			LOGERROR("Cannot find object named '%s' used by tooltip '%s'", usedObjectName.c_str(), style.c_str());
			return;
		}

		// Unhide the object. (If it had use_object and hide_object="true",
		// still unhide it, because the used object might be hidden by default)
		GUI<bool>::SetSetting(usedobj, "hidden", false);
	}
	else
	{
		// Unhide the object
		GUI<bool>::SetSetting(usedobj, "hidden", false);

		// Store mouse position inside the CTooltip
		if (GUI<CPos>::SetSetting(usedobj, "_mousepos", pos) != PSRETURN_OK)
			debug_warn(L"Failed to set tooltip mouse position");
	}

	// Retrieve object's 'tooltip' setting
	CStrW text;
	if (m_IsIconTooltip)
	{
		// Use icon tooltip property
		if (GUI<CStrW>::GetSetting(obj, "_icon_tooltip", text) != PSRETURN_OK)
			debug_warn(L"Failed to retrieve icon tooltip text"); // shouldn't fail
	}
	else
	{
		// Use normal tooltip property
		if (GUI<CStrW>::GetSetting(obj, "tooltip", text) != PSRETURN_OK)
			debug_warn(L"Failed to retrieve tooltip text"); // shouldn't fail
	}

	// Set tooltip's caption
	if (usedobj->SetSetting("caption", text) != PSRETURN_OK)
		debug_warn(L"Failed to set tooltip caption"); // shouldn't fail

	// Make the tooltip object regenerate its text
	SGUIMessage msg(GUIM_SETTINGS_UPDATED, "caption");
	usedobj->HandleMessage(msg);
}

void GUITooltip::HideTooltip(const CStr& style, CGUI* gui)
{
	// Ignore attempts to use tooltip ""
	if (style.empty())
		return;

	IGUIObject* tooltipobj = gui->FindObjectByName("__tooltip_"+style);
	if (!tooltipobj)
	{
		LOGERROR("Cannot find tooltip named '%s'", style.c_str());
		return;
	}

	CStr usedObjectName;
	if (GUI<CStr>::GetSetting(tooltipobj, "use_object", usedObjectName) == PSRETURN_OK
		&& !usedObjectName.empty())
	{
		IGUIObject* usedobj = gui->FindObjectByName(usedObjectName);
		if (!usedobj)
		{
			LOGERROR("Cannot find object named '%s' used by tooltip '%s'", usedObjectName.c_str(), style.c_str());
			return;
		}

		// Clear the caption
		usedobj->SetSetting("caption", L"");
		SGUIMessage msg(GUIM_SETTINGS_UPDATED, "caption");
		usedobj->HandleMessage(msg);

		bool hideobject = true;
		GUI<bool>::GetSetting(tooltipobj, "hide_object", hideobject);

		// If hide_object was enabled, hide it
		if (hideobject)
			GUI<bool>::SetSetting(usedobj, "hidden", true);
	}
	else
	{
		GUI<bool>::SetSetting(tooltipobj, "hidden", true);
	}

}

static int GetTooltipDelay(const CStr& style, CGUI* gui)
{
	int delay = 500; // default value (in msec)

	IGUIObject* tooltipobj = gui->FindObjectByName("__tooltip_"+style);
	if (!tooltipobj)
	{
		LOGERROR("Cannot find tooltip object named '%s'", style.c_str());
		return delay;
	}
	GUI<int>::GetSetting(tooltipobj, "delay", delay);
	return delay;
}

void GUITooltip::Update(IGUIObject* Nearest, const CPos& MousePos, CGUI* GUI)
{
	// Called once per frame, so efficiency isn't vital


	double now = timer_Time();

	CStr style;

	int nextstate = -1;

	switch (m_State)
	{
	case ST_IN_MOTION:
		if (MousePos == m_PreviousMousePos)
		{
			if (GetTooltip(Nearest, style))
				nextstate = ST_STATIONARY_TOOLTIP;
			else
				nextstate = ST_STATIONARY_NO_TOOLTIP;
		}
		else
		{
			// Check for movement onto a zero-delayed tooltip
			if (GetTooltip(Nearest, style) && GetTooltipDelay(style, GUI)==0)
			{
				// Reset any previous tooltips completely
				//m_Time = now + (double)GetTooltipDelay(style, GUI) / 1000.;
				HideTooltip(m_PreviousTooltipName, GUI);

				nextstate = ST_SHOWING;
			}
		}
		break;

	case ST_STATIONARY_NO_TOOLTIP:
		if (MousePos != m_PreviousMousePos)
			nextstate = ST_IN_MOTION;
		break;

	case ST_STATIONARY_TOOLTIP:
		if (MousePos != m_PreviousMousePos)
			nextstate = ST_IN_MOTION;
		else if (now >= m_Time)
		{
			// Make sure the tooltip still exists
			if (GetTooltip(Nearest, style))
				nextstate = ST_SHOWING;
			else
			{
				// Failed to retrieve style - the object has probably been
				// altered, so just restart the process
				nextstate = ST_IN_MOTION;
			}
		}
		break;

	case ST_SHOWING:
		// Handle special case of icon tooltips
		if (Nearest == m_PreviousObject && (!m_IsIconTooltip || Nearest->MouseOverIcon()))
		{
			// Still showing the same object's tooltip, but the text might have changed
			if (GetTooltip(Nearest, style))
				ShowTooltip(Nearest, MousePos, style, GUI);
		}
		else
		{
			// Mouse moved onto a new object

			if (GetTooltip(Nearest, style))
			{
				CStr style_old;

				// If we're displaying a tooltip with no delay, then we want to
				//  reset so that other object that should have delay can't
				//  "ride this tail", it have to wait.
				// Notice that this doesn't apply to when you go from one delay=0
				//  to another delay=0
				if (GetTooltip(m_PreviousObject, style_old) && GetTooltipDelay(style_old, GUI) == 0 &&
					GetTooltipDelay(style, GUI) != 0)
				{
					HideTooltip(m_PreviousTooltipName, GUI);
					nextstate = ST_IN_MOTION;
				}
				else
				{
					// Hide old scrollbar
					HideTooltip(m_PreviousTooltipName, GUI);
					nextstate = ST_SHOWING;
				}
			}
			else
			{
				nextstate = ST_COOLING;
			}
		}
		break;

	case ST_COOLING:
		if (GetTooltip(Nearest, style))
			nextstate = ST_SHOWING;
		else if (now >= m_Time)
			nextstate = ST_IN_MOTION;
		break;
	}

	// Handle state-entry code:

	if (nextstate != -1)
	{
		switch (nextstate)
		{
		case ST_STATIONARY_TOOLTIP:
			m_Time = now + (double)GetTooltipDelay(style, GUI) / 1000.;
			break;

		case ST_SHOWING:
			ShowTooltip(Nearest, MousePos, style, GUI);
			m_PreviousTooltipName = style;
			break;

		case ST_COOLING:
			HideTooltip(m_PreviousTooltipName, GUI);
			m_Time = now + CooldownTime;
			break;
		}

		m_State = nextstate;
	}

	m_PreviousMousePos = MousePos;
	m_PreviousObject = Nearest;
}