/** 
 * @file lllayoutstack.cpp
 * @brief LLLayout class - dynamic stacking of UI elements
 *
 * $LicenseInfo:firstyear=2001&license=viewerlgpl$
 * Second Life Viewer Source Code
 * Copyright (C) 2010, Linden Research, Inc.
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation;
 * version 2.1 of the License only.
 * 
 * This library 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
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 * 
 * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
 * $/LicenseInfo$
 */

// Opaque view with a background and a border.  Can contain LLUICtrls.

#include "linden_common.h"

#include "lllayoutstack.h"

#include "lllocalcliprect.h"
#include "llpanel.h"
#include "llresizebar.h"
#include "llcriticaldamp.h"

static LLDefaultChildRegistry::Register<LLLayoutStack> register_layout_stack("layout_stack");
static LLLayoutStack::LayoutStackRegistry::Register<LLLayoutPanel> register_layout_panel("layout_panel");

void LLLayoutStack::OrientationNames::declareValues()
{
	declare("horizontal", HORIZONTAL);
	declare("vertical", VERTICAL);
}

//
// LLLayoutPanel
//
LLLayoutPanel::Params::Params()	
:	expanded_min_dim("expanded_min_dim", 0),
	min_dim("min_dim", 0),
	max_dim("max_dim", S32_MAX),
	user_resize("user_resize", true),
	auto_resize("auto_resize", true)
{
	addSynonym(min_dim, "min_width");
	addSynonym(min_dim, "min_height");
	addSynonym(max_dim, "max_width");
	addSynonym(max_dim, "max_height");
}

LLLayoutPanel::LLLayoutPanel(const Params& p)	
:	LLPanel(p),
	mExpandedMinDimSpecified(false),
	mExpandedMinDim(p.min_dim),
 	mMinDim(p.min_dim), 
 	mMaxDim(p.max_dim), 
 	mAutoResize(p.auto_resize),
 	mUserResize(p.user_resize),
	mCollapsed(FALSE),
	mCollapseAmt(0.f),
	mVisibleAmt(1.f), // default to fully visible
	mResizeBar(NULL),
	mFractionalSize(0.f),
	mOrientation(LLLayoutStack::HORIZONTAL)
{
	// Set the expanded min dim if it is provided, otherwise it gets the p.min_dim value
	if (p.expanded_min_dim.isProvided())
	{
		mExpandedMinDimSpecified = true;
		mExpandedMinDim = p.expanded_min_dim();
	}
	
	// panels initialized as hidden should not start out partially visible
	if (!getVisible())
	{
		mVisibleAmt = 0.f;
	}
}

void LLLayoutPanel::initFromParams(const Params& p)
{
	LLPanel::initFromParams(p);
	setFollowsNone();
}


LLLayoutPanel::~LLLayoutPanel()
{
	// probably not necessary, but...
	delete mResizeBar;
	mResizeBar = NULL;
}

void LLLayoutPanel::reshape(S32 width, S32 height, BOOL called_from_parent)
{
	if (mOrientation == LLLayoutStack::HORIZONTAL)
	{
		mFractionalSize += width - llround(mFractionalSize);
	}
	else
	{
		mFractionalSize += height - llround(mFractionalSize);
	}
	LLPanel::reshape(width, height, called_from_parent);
}

F32 LLLayoutPanel::getCollapseFactor()
{
	if (mOrientation == LLLayoutStack::HORIZONTAL)
	{
		F32 collapse_amt = 
			clamp_rescale(mCollapseAmt, 0.f, 1.f, 1.f, (F32)getRelevantMinDim() / (F32)llmax(1, getRect().getWidth()));
		return mVisibleAmt * collapse_amt;
	}
	else
	{
		F32 collapse_amt = 
			clamp_rescale(mCollapseAmt, 0.f, 1.f, 1.f, llmin(1.f, (F32)getRelevantMinDim() / (F32)llmax(1, getRect().getHeight())));
		return mVisibleAmt * collapse_amt;
	}
}

//
// LLLayoutStack
//

LLLayoutStack::Params::Params()
:	orientation("orientation"),
	animate("animate", true),
	clip("clip", true),
	open_time_constant("open_time_constant", 0.02f),
	close_time_constant("close_time_constant", 0.03f),
	border_size("border_size", LLCachedControl<S32>(*LLUI::sSettingGroups["config"], "UIResizeBarHeight", 0))
{}

LLLayoutStack::LLLayoutStack(const LLLayoutStack::Params& p) 
:	LLView(p),
	mMinWidth(0),
	mMinHeight(0),
	mPanelSpacing(p.border_size),
	mOrientation(p.orientation),
	mAnimate(p.animate),
	mAnimatedThisFrame(false),
	mClip(p.clip),
	mOpenTimeConstant(p.open_time_constant),
	mCloseTimeConstant(p.close_time_constant)
{}

LLLayoutStack::~LLLayoutStack()
{
	e_panel_list_t panels = mPanels; // copy list of panel pointers
	mPanels.clear(); // clear so that removeChild() calls don't cause trouble
	std::for_each(panels.begin(), panels.end(), DeletePointer());
}

void LLLayoutStack::draw()
{
	updateLayout();

	e_panel_list_t::iterator panel_it;
	for (panel_it = mPanels.begin(); panel_it != mPanels.end(); ++panel_it)
	{
		// clip to layout rectangle, not bounding rectangle
		LLRect clip_rect = (*panel_it)->getRect();
		// scale clipping rectangle by visible amount
		if (mOrientation == HORIZONTAL)
		{
			clip_rect.mRight = clip_rect.mLeft + llround((F32)clip_rect.getWidth() * (*panel_it)->getCollapseFactor());
		}
		else
		{
			clip_rect.mBottom = clip_rect.mTop - llround((F32)clip_rect.getHeight() * (*panel_it)->getCollapseFactor());
		}

		LLPanel* panelp = (*panel_it);

		LLLocalClipRect clip(clip_rect, mClip);
		// only force drawing invisible children if visible amount is non-zero
		drawChild(panelp, 0, 0, !clip_rect.isEmpty());
	}
	mAnimatedThisFrame = false;
}

void LLLayoutStack::removeChild(LLView* view)
{
	LLLayoutPanel* embedded_panelp = findEmbeddedPanel(dynamic_cast<LLPanel*>(view));

	if (embedded_panelp)
	{
		mPanels.erase(std::find(mPanels.begin(), mPanels.end(), embedded_panelp));
		delete embedded_panelp;
	}

	// need to update resizebars

	calcMinExtents();

	LLView::removeChild(view);
}

BOOL LLLayoutStack::postBuild()
{
	updateLayout();
	return TRUE;
}

bool LLLayoutStack::addChild(LLView* child, S32 tab_group)
{
	LLLayoutPanel* panelp = dynamic_cast<LLLayoutPanel*>(child);
	if (panelp)
	{
		panelp->mFractionalSize = (mOrientation == HORIZONTAL)
									? panelp->getRect().getWidth()
									: panelp->getRect().getHeight();
		panelp->setOrientation(mOrientation);
		mPanels.push_back(panelp);
	}
	return LLView::addChild(child, tab_group);
}

void LLLayoutStack::movePanel(LLPanel* panel_to_move, LLPanel* target_panel, bool move_to_front)
{
	LLLayoutPanel* embedded_panel_to_move = findEmbeddedPanel(panel_to_move);
	LLLayoutPanel* embedded_target_panel = move_to_front ? *mPanels.begin() : findEmbeddedPanel(target_panel);

	if (!embedded_panel_to_move || !embedded_target_panel || embedded_panel_to_move == embedded_target_panel)
	{
		llwarns << "One of the panels was not found in stack or NULL was passed instead of valid panel" << llendl;
		return;
	}
	e_panel_list_t::iterator it = std::find(mPanels.begin(), mPanels.end(), embedded_panel_to_move);
	mPanels.erase(it);
	it = move_to_front ? mPanels.begin() : std::find(mPanels.begin(), mPanels.end(), embedded_target_panel);
	mPanels.insert(it, embedded_panel_to_move);
}

void LLLayoutStack::addPanel(LLLayoutPanel* panel, EAnimate animate)
{
	addChild(panel);

	// panel starts off invisible (collapsed)
	if (animate == ANIMATE)
	{
		panel->mVisibleAmt = 0.f;
		panel->setVisible(TRUE);
	}
}

void LLLayoutStack::removePanel(LLPanel* panel)
{
	removeChild(panel);
}

void LLLayoutStack::collapsePanel(LLPanel* panel, BOOL collapsed)
{
	LLLayoutPanel* panel_container = findEmbeddedPanel(panel);
	if (!panel_container) return;

	panel_container->mCollapsed = collapsed;
}

void LLLayoutStack::updatePanelAutoResize(const std::string& panel_name, BOOL auto_resize)
{
	LLLayoutPanel* panel = findEmbeddedPanelByName(panel_name);

	if (panel)
	{
		panel->mAutoResize = auto_resize;
	}
}

void LLLayoutStack::setPanelUserResize(const std::string& panel_name, BOOL user_resize)
{
	LLLayoutPanel* panel = findEmbeddedPanelByName(panel_name);

	if (panel)
	{
		panel->mUserResize = user_resize;
	}
}

bool LLLayoutStack::getPanelMinSize(const std::string& panel_name, S32* min_dimp)
{
	LLLayoutPanel* panel = findEmbeddedPanelByName(panel_name);

	if (panel && min_dimp)
	{
		*min_dimp = panel->getRelevantMinDim();
	}

	return NULL != panel;
}

bool LLLayoutStack::getPanelMaxSize(const std::string& panel_name, S32* max_dimp)
{
	LLLayoutPanel* panel = findEmbeddedPanelByName(panel_name);

	if (panel)
	{
		if (max_dimp) *max_dimp = panel->mMaxDim;
	}

	return NULL != panel;
}

static LLFastTimer::DeclareTimer FTM_UPDATE_LAYOUT("Update LayoutStacks");
void LLLayoutStack::updateLayout(BOOL force_resize)
{
	LLFastTimer ft(FTM_UPDATE_LAYOUT);
	static LLUICachedControl<S32> resize_bar_overlap ("UIResizeBarOverlap", 0);
	calcMinExtents();
	createResizeBars();

	// calculate current extents
	F32 total_size = 0.f;

	//
	// animate visibility
	//
	e_panel_list_t::iterator panel_it;
	for (panel_it = mPanels.begin(); panel_it != mPanels.end();	++panel_it)
	{
		LLLayoutPanel* panelp = (*panel_it);
		if (panelp->getVisible()) 
		{
			if (mAnimate)
			{
				if (!mAnimatedThisFrame)
				{
					panelp->mVisibleAmt = lerp(panelp->mVisibleAmt, 1.f, LLCriticalDamp::getInterpolant(mOpenTimeConstant));
					if (panelp->mVisibleAmt > 0.99f)
					{
						panelp->mVisibleAmt = 1.f;
					}
				}
			}
			else
			{
				panelp->mVisibleAmt = 1.f;
			}
		}
		else // not visible
		{
			if (mAnimate)
			{
				if (!mAnimatedThisFrame)
				{
					panelp->mVisibleAmt = lerp(panelp->mVisibleAmt, 0.f, LLCriticalDamp::getInterpolant(mCloseTimeConstant));
					if (panelp->mVisibleAmt < 0.001f)
					{
						panelp->mVisibleAmt = 0.f;
					}
				}
			}
			else
			{
				panelp->mVisibleAmt = 0.f;
			}
		}

		F32 collapse_state = panelp->mCollapsed ? 1.f : 0.f;
		panelp->mCollapseAmt = lerp(panelp->mCollapseAmt, collapse_state, LLCriticalDamp::getInterpolant(mCloseTimeConstant));

        total_size += panelp->mFractionalSize * panelp->getCollapseFactor();
        // want n-1 panel gaps for n panels
		if (panel_it != mPanels.begin())
		{
			total_size += mPanelSpacing;
		}
	}

	S32 num_resizable_panels = 0;
	F32 shrink_headroom_available = 0.f;
	F32 shrink_headroom_total = 0.f;
	for (panel_it = mPanels.begin(); panel_it != mPanels.end(); ++panel_it)
	{
		LLLayoutPanel* panelp = (*panel_it);

		// panels that are not fully visible do not count towards shrink headroom
		if (panelp->getCollapseFactor() < 1.f) 
		{
			continue;
		}

		F32 cur_size = panelp->mFractionalSize;
		F32 min_size = (F32)panelp->getRelevantMinDim();
		
		// if currently resizing a panel or the panel is flagged as not automatically resizing
		// only track total available headroom, but don't use it for automatic resize logic
		if (panelp->mResizeBar->hasMouseCapture() 
			|| (!panelp->mAutoResize 
				&& !force_resize))
		{
			shrink_headroom_total += cur_size - min_size;
		}
		else
		{
			num_resizable_panels++;
			
			shrink_headroom_available += cur_size - min_size;
			shrink_headroom_total += cur_size - min_size;
		}
	}

	// calculate how many pixels need to be distributed among layout panels
	// positive means panels need to grow, negative means shrink
	F32 pixels_to_distribute = (mOrientation == HORIZONTAL)
							? getRect().getWidth() - total_size
							: getRect().getHeight() - total_size;

	// now we distribute the pixels...
	F32 cur_x = 0.f;
	F32 cur_y = (F32)getRect().getHeight();

	for (panel_it = mPanels.begin(); panel_it != mPanels.end(); ++panel_it)
	{
		LLLayoutPanel* panelp = (*panel_it);

		F32 min_size = panelp->getRelevantMinDim();
		F32 delta_size = 0.f;

		// if panel can automatically resize (not animating, and resize flag set)...
		if (panelp->getCollapseFactor() == 1.f 
			&& (force_resize || panelp->mAutoResize) 
			&& !panelp->mResizeBar->hasMouseCapture()) 
		{
			if (pixels_to_distribute < 0.f)
			{
				// shrink proportionally to amount over minimum
				// so we can do this in one pass
				delta_size = (shrink_headroom_available > 0.f) 
					? pixels_to_distribute * ((F32)(panelp->mFractionalSize - min_size) / shrink_headroom_available) 
					: 0.f;
				shrink_headroom_available -= (panelp->mFractionalSize - min_size);
			}
			else
			{
				// grow all elements equally
				delta_size = pixels_to_distribute / (F32)num_resizable_panels;
				num_resizable_panels--;
			}
			
			panelp->mFractionalSize = llmax(min_size, panelp->mFractionalSize + delta_size);
			pixels_to_distribute -= delta_size;
		}

		// adjust running headroom count based on new sizes
		shrink_headroom_total += delta_size;

		LLRect panel_rect;
		if (mOrientation == HORIZONTAL)
		{
			panel_rect.setLeftTopAndSize(llround(cur_x), 
										llround(cur_y), 
										llround(panelp->mFractionalSize), 
										getRect().getHeight());
		}
		else
		{
			panel_rect.setLeftTopAndSize(llround(cur_x), 
										llround(cur_y), 
										getRect().getWidth(), 
										llround(panelp->mFractionalSize));
		}
		panelp->setShape(panel_rect);

		LLRect resize_bar_rect = panel_rect;
		if (mOrientation == HORIZONTAL)
		{
			resize_bar_rect.mLeft = panel_rect.mRight - resize_bar_overlap;
			resize_bar_rect.mRight = panel_rect.mRight + mPanelSpacing + resize_bar_overlap;
		}
		else
		{
			resize_bar_rect.mTop = panel_rect.mBottom + resize_bar_overlap;
			resize_bar_rect.mBottom = panel_rect.mBottom - mPanelSpacing - resize_bar_overlap;
		}
		(*panel_it)->mResizeBar->setRect(resize_bar_rect);

		F32 size = ((*panel_it)->mFractionalSize * (*panel_it)->getCollapseFactor()) + (F32)mPanelSpacing;
		if (mOrientation == HORIZONTAL)
		{
			cur_x += size;
		}
		else //VERTICAL
		{
			cur_y -= size;
		}
	}

	// update resize bars with new limits
	LLLayoutPanel* last_resizeable_panel = NULL;
	for (panel_it = mPanels.begin(); panel_it != mPanels.end(); ++panel_it)
	{
		LLLayoutPanel* panelp = (*panel_it);
		S32 relevant_min = panelp->getRelevantMinDim();

		if (mOrientation == HORIZONTAL)
		{
			(*panel_it)->mResizeBar->setResizeLimits(
				relevant_min, 
				relevant_min + llround(shrink_headroom_total));
		}
		else //VERTICAL
		{
			(*panel_it)->mResizeBar->setResizeLimits(
				relevant_min, 
				relevant_min + llround(shrink_headroom_total));
		}

		// toggle resize bars based on panel visibility, resizability, etc
		BOOL resize_bar_enabled = panelp->getVisible() && (*panel_it)->mUserResize;
		(*panel_it)->mResizeBar->setVisible(resize_bar_enabled);

		if ((*panel_it)->mUserResize || (*panel_it)->mAutoResize)
		{
			last_resizeable_panel = (*panel_it);
		}
	}

	// hide last resize bar as there is nothing past it
	// resize bars need to be in between two resizable panels
	if (last_resizeable_panel)
	{
		last_resizeable_panel->mResizeBar->setVisible(FALSE);
	}

	// not enough room to fit existing contents
	if (force_resize == FALSE
		// layout did not complete by reaching target position
		&& ((mOrientation == VERTICAL && llround(cur_y) != -mPanelSpacing)
			|| (mOrientation == HORIZONTAL && llround(cur_x) != getRect().getWidth() + mPanelSpacing)))
	{
		// do another layout pass with all stacked elements contributing
		// even those that don't usually resize
		llassert_always(force_resize == FALSE);
		updateLayout(TRUE);
	}

	 mAnimatedThisFrame = true;
} // end LLLayoutStack::updateLayout


LLLayoutPanel* LLLayoutStack::findEmbeddedPanel(LLPanel* panelp) const
{
	if (!panelp) return NULL;

	e_panel_list_t::const_iterator panel_it;
	for (panel_it = mPanels.begin(); panel_it != mPanels.end(); ++panel_it)
	{
		if ((*panel_it) == panelp)
		{
			return *panel_it;
		}
	}
	return NULL;
}

LLLayoutPanel* LLLayoutStack::findEmbeddedPanelByName(const std::string& name) const
{
	LLLayoutPanel* result = NULL;

	for (e_panel_list_t::const_iterator panel_it = mPanels.begin(); panel_it != mPanels.end(); ++panel_it)
	{
		LLLayoutPanel* p = *panel_it;

		if (p->getName() == name)
		{
			result = p;
			break;
		}
	}

	return result;
}

// Compute sum of min_width or min_height of children
void LLLayoutStack::calcMinExtents()
{
	mMinWidth = 0;
	mMinHeight = 0;

	e_panel_list_t::iterator panel_it;
	for (panel_it = mPanels.begin(); panel_it != mPanels.end(); ++panel_it)
	{
		if (mOrientation == HORIZONTAL)
		{
            mMinWidth += (*panel_it)->getRelevantMinDim();
			if (panel_it != mPanels.begin())
			{
				mMinWidth += mPanelSpacing;
			}
		}
		else //VERTICAL
		{
			mMinHeight += (*panel_it)->getRelevantMinDim();
			if (panel_it != mPanels.begin())
			{
				mMinHeight += mPanelSpacing;
			}
		}
	}
}

void LLLayoutStack::createResizeBars()
{
	for (e_panel_list_t::iterator panel_it = mPanels.begin(); panel_it != mPanels.end(); ++panel_it)
	{
		LLLayoutPanel* lp = (*panel_it);
		if (lp->mResizeBar == NULL)
		{
			LLResizeBar::Side side = (mOrientation == HORIZONTAL) ? LLResizeBar::RIGHT : LLResizeBar::BOTTOM;
			LLRect resize_bar_rect = getRect();

			LLResizeBar::Params resize_params;
			resize_params.name("resize");
			resize_params.resizing_view(lp);
			resize_params.min_size(lp->getRelevantMinDim());
			resize_params.side(side);
			resize_params.snapping_enabled(false);
			LLResizeBar* resize_bar = LLUICtrlFactory::create<LLResizeBar>(resize_params);
			lp->mResizeBar = resize_bar;
			LLView::addChild(resize_bar, 0);

			// bring all resize bars to the front so that they are clickable even over the panels
			// with a bit of overlap
			for (e_panel_list_t::iterator panel_it = mPanels.begin(); panel_it != mPanels.end(); ++panel_it)
			{
				LLResizeBar* resize_barp = (*panel_it)->mResizeBar;
				sendChildToFront(resize_barp);
			}
		}
	}
}

// update layout stack animations, etc. once per frame
// NOTE: we use this to size world view based on animating UI, *before* we draw the UI
// we might still need to call updateLayout during UI draw phase, in case UI elements
// are resizing themselves dynamically
//static 
void LLLayoutStack::updateClass()
{
	for (instance_iter it = beginInstances(); it != endInstances(); ++it)
	{
		it->updateLayout();
	}
}