/*
 * Copyright 2008-2015, Axel Dörfler, axeld@pinc-software.de.
 * Distributed under the terms of the MIT License.
 */


#include "ActivityView.h"

#include <new>
#include <stdio.h>
#include <stdlib.h>
#include <vector>

#ifdef __HAIKU__
#	include <AboutWindow.h>
#	include <AbstractLayoutItem.h>
#	include <ControlLook.h>
#endif
#include <Application.h>
#include <Autolock.h>
#include <Bitmap.h>
#include <Catalog.h>
#include <Dragger.h>
#include <MenuItem.h>
#include <MessageRunner.h>
#include <PopUpMenu.h>
#include <Shape.h>
#include <String.h>

#include "ActivityMonitor.h"
#include "ActivityWindow.h"
#include "SettingsWindow.h"
#include "SystemInfo.h"
#include "SystemInfoHandler.h"

#undef B_TRANSLATION_CONTEXT
#define B_TRANSLATION_CONTEXT "ActivityView"

template<typename ObjectType>
class ListAddDeleter {
public:
	ListAddDeleter(BObjectList<ObjectType>& list, ObjectType* object,
			int32 spot)
		:
		fList(list),
		fObject(object)
	{
		if (fObject != NULL && !fList.AddItem(fObject, spot)) {
			delete fObject;
			fObject = NULL;
		}
	}

	~ListAddDeleter()
	{
		if (fObject != NULL) {
			fList.RemoveItem(fObject);
			delete fObject;
		}
	}

	bool Failed() const
	{
		return fObject == NULL;
	}

	void Detach()
	{
		fObject = NULL;
	}

private:
	BObjectList<ObjectType>&	fList;
	ObjectType*					fObject;
};


/*!	This class manages the scale of a history with a dynamic scale.
	Every history value will be input via Update(), and the minimum/maximum
	is computed from that.
*/
class Scale {
public:
								Scale(scale_type type);

			int64				MinimumValue() const { return fMinimumValue; }
			int64				MaximumValue() const { return fMaximumValue; }

			void				Update(int64 value);

private:
			scale_type			fType;
			int64				fMinimumValue;
			int64				fMaximumValue;
			bool				fInitialized;
};

/*!	Stores the interpolated on screen view values. This is done so that the
	interpolation is fixed, and does not change when being scrolled.

	We could also just do this by making sure we always ask for the same
	interval only, but this way we also save the interpolation.
*/
class ViewHistory {
public:
								ViewHistory();

			int64				ValueAt(int32 x);

			int32				Start() const
									{ return fValues.Size()
										- fValues.CountItems(); }

			void				Update(DataHistory* history, int32 width,
									int32 resolution, bigtime_t toTime,
									bigtime_t step, bigtime_t refresh);

private:
			CircularBuffer<int64> fValues;
			int32				fResolution;
			bigtime_t			fRefresh;
			bigtime_t			fLastTime;
};

struct data_item {
	bigtime_t	time;
	int64		value;
};

#ifdef __HAIKU__
class ActivityView::HistoryLayoutItem : public BAbstractLayoutItem {
public:
							HistoryLayoutItem(ActivityView* parent);

	virtual	bool			IsVisible();
	virtual	void			SetVisible(bool visible);

	virtual	BRect			Frame();
	virtual	void			SetFrame(BRect frame);

	virtual	BView*			View();

	virtual	BSize			BasePreferredSize();

private:
	ActivityView*			fParent;
	BRect					fFrame;
};

class ActivityView::LegendLayoutItem : public BAbstractLayoutItem {
public:
							LegendLayoutItem(ActivityView* parent);

	virtual	bool			IsVisible();
	virtual	void			SetVisible(bool visible);

	virtual	BRect			Frame();
	virtual	void			SetFrame(BRect frame);

	virtual	BView*			View();

	virtual	BSize			BaseMinSize();
	virtual	BSize			BaseMaxSize();
	virtual	BSize			BasePreferredSize();
	virtual	BAlignment		BaseAlignment();

private:
	ActivityView*			fParent;
	BRect					fFrame;
};
#endif

const bigtime_t kInitialRefreshInterval = 250000LL;

const uint32 kMsgToggleDataSource = 'tgds';
const uint32 kMsgToggleLegend = 'tglg';
const uint32 kMsgUpdateResolution = 'ures';

extern const char* kAppName;
extern const char* kSignature;


Scale::Scale(scale_type type)
	:
	fType(type),
	fMinimumValue(0),
	fMaximumValue(0),
	fInitialized(false)
{
}


void
Scale::Update(int64 value)
{
	if (!fInitialized || fMinimumValue > value)
		fMinimumValue = value;
	if (!fInitialized || fMaximumValue < value)
		fMaximumValue = value;

	fInitialized = true;
}


//	#pragma mark -


ViewHistory::ViewHistory()
	:
	fValues(1),
	fResolution(-1),
	fRefresh(-1),
	fLastTime(0)
{
}


int64
ViewHistory::ValueAt(int32 x)
{
	int64* value = fValues.ItemAt(x - Start());
	if (value != NULL)
		return *value;

	return 0;
}


void
ViewHistory::Update(DataHistory* history, int32 width, int32 resolution,
	bigtime_t toTime, bigtime_t step, bigtime_t refresh)
{
	if (width > 16384) {
		// ignore this - it seems the view hasn't been layouted yet
		return;
	}

	// Check if we need to invalidate the existing values
	if ((int32)fValues.Size() != width
		|| fResolution != resolution
		|| fRefresh != refresh) {
		fValues.SetSize(width);
		fResolution = resolution;
		fRefresh = refresh;
		fLastTime = 0;
	}

	// Compute how many new values we need to retrieve
	if (fLastTime < history->Start())
		fLastTime = history->Start();
	if (fLastTime > history->End())
		return;

	int32 updateWidth = int32((toTime - fLastTime) / step);
	if (updateWidth < 1)
		return;

	if (updateWidth > (int32)fValues.Size()) {
		updateWidth = fValues.Size();
		fLastTime = toTime - updateWidth * step;
	}

	for (int32 i = 0; i < updateWidth; i++) {
		int64 value = history->ValueAt(fLastTime += step);

		if (step > refresh) {
			uint32 count = 1;
			for (bigtime_t offset = refresh; offset < step; offset += refresh) {
				// TODO: handle int64 overflow correctly!
				value += history->ValueAt(fLastTime + offset);
				count++;
			}
			value /= count;
		}

		fValues.AddItem(value);
	}
}


//	#pragma mark -


DataHistory::DataHistory(bigtime_t memorize, bigtime_t interval)
	:
	fBuffer(10000),
	fMinimumValue(0),
	fMaximumValue(0),
	fRefreshInterval(interval),
	fLastIndex(-1),
	fScale(NULL)
{
}


DataHistory::~DataHistory()
{
}


void
DataHistory::AddValue(bigtime_t time, int64 value)
{
	if (fBuffer.IsEmpty() || fMaximumValue < value)
		fMaximumValue = value;
	if (fBuffer.IsEmpty() || fMinimumValue > value)
		fMinimumValue = value;
	if (fScale != NULL)
		fScale->Update(value);

	data_item item = {time, value};
	fBuffer.AddItem(item);
}


int64
DataHistory::ValueAt(bigtime_t time)
{
	int32 left = 0;
	int32 right = fBuffer.CountItems() - 1;
	data_item* item = NULL;

	while (left <= right) {
		int32 index = (left + right) / 2;
		item = fBuffer.ItemAt(index);

		if (item->time > time) {
			// search in left part
			right = index - 1;
		} else {
			data_item* nextItem = fBuffer.ItemAt(index + 1);
			if (nextItem == NULL)
				return item->value;
			if (nextItem->time > time) {
				// found item
				int64 value = item->value;
				value += int64(double(nextItem->value - value)
					/ (nextItem->time - item->time) * (time - item->time));
				return value;
			}

			// search in right part
			left = index + 1;
		}
	}

	return 0;
}


int64
DataHistory::MaximumValue() const
{
	if (fScale != NULL)
		return fScale->MaximumValue();

	return fMaximumValue;
}


int64
DataHistory::MinimumValue() const
{
	if (fScale != NULL)
		return fScale->MinimumValue();

	return fMinimumValue;
}


bigtime_t
DataHistory::Start() const
{
	if (fBuffer.CountItems() == 0)
		return 0;

	return fBuffer.ItemAt(0)->time;
}


bigtime_t
DataHistory::End() const
{
	if (fBuffer.CountItems() == 0)
		return 0;

	return fBuffer.ItemAt(fBuffer.CountItems() - 1)->time;
}


void
DataHistory::SetRefreshInterval(bigtime_t interval)
{
	// TODO: adjust buffer size
}


void
DataHistory::SetScale(Scale* scale)
{
	fScale = scale;
}


//	#pragma mark -


#ifdef __HAIKU__
ActivityView::HistoryLayoutItem::HistoryLayoutItem(ActivityView* parent)
	:
	fParent(parent),
	fFrame()
{
}


bool
ActivityView::HistoryLayoutItem::IsVisible()
{
	return !fParent->IsHidden(fParent);
}


void
ActivityView::HistoryLayoutItem::SetVisible(bool visible)
{
	// not allowed
}


BRect
ActivityView::HistoryLayoutItem::Frame()
{
	return fFrame;
}


void
ActivityView::HistoryLayoutItem::SetFrame(BRect frame)
{
	fFrame = frame;
	fParent->_UpdateFrame();
}


BView*
ActivityView::HistoryLayoutItem::View()
{
	return fParent;
}


BSize
ActivityView::HistoryLayoutItem::BasePreferredSize()
{
	BSize size(BaseMaxSize());
	return size;
}


//	#pragma mark -


ActivityView::LegendLayoutItem::LegendLayoutItem(ActivityView* parent)
	:
	fParent(parent),
	fFrame()
{
}


bool
ActivityView::LegendLayoutItem::IsVisible()
{
	return !fParent->IsHidden(fParent);
}


void
ActivityView::LegendLayoutItem::SetVisible(bool visible)
{
	// not allowed
}


BRect
ActivityView::LegendLayoutItem::Frame()
{
	return fFrame;
}


void
ActivityView::LegendLayoutItem::SetFrame(BRect frame)
{
	fFrame = frame;
	fParent->_UpdateFrame();
}


BView*
ActivityView::LegendLayoutItem::View()
{
	return fParent;
}


BSize
ActivityView::LegendLayoutItem::BaseMinSize()
{
	// TODO: Cache the info. Might be too expensive for this call.
	BSize size;
	size.width = 80;
	size.height = fParent->_LegendHeight();

	return size;
}


BSize
ActivityView::LegendLayoutItem::BaseMaxSize()
{
	BSize size(BaseMinSize());
	size.width = B_SIZE_UNLIMITED;
	return size;
}


BSize
ActivityView::LegendLayoutItem::BasePreferredSize()
{
	BSize size(BaseMinSize());
	return size;
}


BAlignment
ActivityView::LegendLayoutItem::BaseAlignment()
{
	return BAlignment(B_ALIGN_USE_FULL_WIDTH, B_ALIGN_USE_FULL_HEIGHT);
}
#endif


//	#pragma mark -


const rgb_color kWhite = (rgb_color){255, 255, 255, 255};
const rgb_color kBlack = (rgb_color){0, 0, 0, 255};
const float kDraggerSize = 7;


ActivityView::ActivityView(BRect frame, const char* name,
		const BMessage* settings, uint32 resizingMode)
	: BView(frame, name, resizingMode,
		B_WILL_DRAW | B_FULL_UPDATE_ON_RESIZE | B_FRAME_EVENTS),
	fSourcesLock("data sources")
{
	_Init(settings);

	BRect rect(Bounds());
	rect.top = rect.bottom - kDraggerSize;
	rect.left = rect.right - kDraggerSize;
	BDragger* dragger = new BDragger(rect, this,
		B_FOLLOW_RIGHT | B_FOLLOW_BOTTOM);
	AddChild(dragger);
}


ActivityView::ActivityView(const char* name, const BMessage* settings)
#ifdef __HAIKU__
	: BView(name, B_WILL_DRAW | B_FULL_UPDATE_ON_RESIZE | B_FRAME_EVENTS),
#else
	: BView(BRect(0, 0, 300, 200), name, B_FOLLOW_NONE,
		B_WILL_DRAW | B_FULL_UPDATE_ON_RESIZE | B_FRAME_EVENTS),
#endif
	fSourcesLock("data sources")
{
	SetLowUIColor(B_PANEL_BACKGROUND_COLOR);

	_Init(settings);

	BRect rect(Bounds());
	rect.top = rect.bottom - kDraggerSize;
	rect.left = rect.right - kDraggerSize;
	BDragger* dragger = new BDragger(rect, this,
		B_FOLLOW_RIGHT | B_FOLLOW_BOTTOM);
	AddChild(dragger);
}


ActivityView::ActivityView(BMessage* archive)
	: BView(archive)
{
	_Init(archive);
}


ActivityView::~ActivityView()
{
	delete fOffscreen;
	delete fSystemInfoHandler;
}


void
ActivityView::_Init(const BMessage* settings)
{
	fHistoryBackgroundColor = (rgb_color){255, 255, 240};
	fLegendBackgroundColor = LowColor();
		// the low color is restored by the BView unarchiving
	fOffscreen = NULL;
#ifdef __HAIKU__
	fHistoryLayoutItem = NULL;
	fLegendLayoutItem = NULL;
#endif
	SetViewColor(B_TRANSPARENT_COLOR);
	SetFlags(Flags() | B_TRANSPARENT_BACKGROUND);

	fLastRefresh = 0;
	fDrawResolution = 1;
	fZooming = false;

	fSystemInfoHandler = new SystemInfoHandler;

	if (settings == NULL
		|| settings->FindInt64("refresh interval", &fRefreshInterval) != B_OK)
		fRefreshInterval = kInitialRefreshInterval;

	if (settings == NULL
		|| settings->FindBool("show legend", &fShowLegend) != B_OK)
		fShowLegend = true;

	if (settings == NULL)
		return;

	ssize_t colorLength;
	rgb_color *color;
	if (settings->FindData("history background color", B_RGB_COLOR_TYPE,
			(const void **)&color, &colorLength) == B_OK
		&& colorLength == sizeof(rgb_color))
		fHistoryBackgroundColor = *color;

	const char* name;
	for (int32 i = 0; settings->FindString("source", i, &name) == B_OK; i++)
		AddDataSource(DataSource::FindSource(name), settings);
}


status_t
ActivityView::Archive(BMessage* into, bool deep) const
{
	status_t status;

	status = BView::Archive(into, deep);
	if (status < B_OK)
		return status;

	status = into->AddString("add_on", kSignature);
	if (status < B_OK)
		return status;

	status = SaveState(*into);
	if (status < B_OK)
		return status;

	return B_OK;
}


BArchivable*
ActivityView::Instantiate(BMessage* archive)
{
	if (!validate_instantiation(archive, "ActivityView"))
		return NULL;

	return new ActivityView(archive);
}


status_t
ActivityView::SaveState(BMessage& state) const
{
	status_t status = state.AddBool("show legend", fShowLegend);
	if (status != B_OK)
		return status;

	status = state.AddInt64("refresh interval", fRefreshInterval);
	if (status != B_OK)
		return status;

	status = state.AddData("history background color", B_RGB_COLOR_TYPE,
		&fHistoryBackgroundColor, sizeof(rgb_color));
	if (status != B_OK)
		return status;

	for (int32 i = 0; i < fSources.CountItems(); i++) {
		DataSource* source = fSources.ItemAt(i);

		if (!source->PerCPU() || source->CPU() == 0)
			status = state.AddString("source", source->InternalName());
		if (status != B_OK)
			return status;

		BString name = source->Name();
		name << " color";
		rgb_color color = source->Color();
		state.AddData(name.String(), B_RGB_COLOR_TYPE, &color,
			sizeof(rgb_color));
	}
	return B_OK;
}


Scale*
ActivityView::_ScaleFor(scale_type type)
{
	if (type == kNoScale)
		return NULL;

	std::map<scale_type, ::Scale*>::iterator iterator = fScales.find(type);
	if (iterator != fScales.end())
		return iterator->second;

	// add new scale
	::Scale* scale = new ::Scale(type);
	fScales[type] = scale;

	return scale;
}


#ifdef __HAIKU__
BLayoutItem*
ActivityView::CreateHistoryLayoutItem()
{
	if (fHistoryLayoutItem == NULL)
		fHistoryLayoutItem = new HistoryLayoutItem(this);

	return fHistoryLayoutItem;
}


BLayoutItem*
ActivityView::CreateLegendLayoutItem()
{
	if (fLegendLayoutItem == NULL)
		fLegendLayoutItem = new LegendLayoutItem(this);

	return fLegendLayoutItem;
}
#endif


DataSource*
ActivityView::FindDataSource(const DataSource* search)
{
	BAutolock _(fSourcesLock);

	for (int32 i = fSources.CountItems(); i-- > 0;) {
		DataSource* source = fSources.ItemAt(i);
		if (!strcmp(source->Name(), search->Name()))
			return source;
	}

	return NULL;
}


status_t
ActivityView::AddDataSource(const DataSource* source, const BMessage* state)
{
	if (source == NULL)
		return B_BAD_VALUE;

	BAutolock _(fSourcesLock);

	// Search for the correct insert spot to maintain the order of the sources
	int32 insert = DataSource::IndexOf(source);
	for (int32 i = 0; i < fSources.CountItems() && i < insert; i++) {
		DataSource* before = fSources.ItemAt(i);
		if (DataSource::IndexOf(before) > insert) {
			insert = i;
			break;
		}
	}
	if (insert > fSources.CountItems())
		insert = fSources.CountItems();

	// Generate DataHistory and ViewHistory objects for the source
	// (one might need one history per CPU)

	uint32 count = 1;
	if (source->PerCPU()) {
		SystemInfo info;
		count = info.CPUCount();
	}

	for (uint32 i = 0; i < count; i++) {
		DataHistory* values = new(std::nothrow) DataHistory(10 * 60000000LL,
			RefreshInterval());
		ListAddDeleter<DataHistory> valuesDeleter(fValues, values, insert);

		ViewHistory* viewValues = new(std::nothrow) ViewHistory;
		ListAddDeleter<ViewHistory> viewValuesDeleter(fViewValues, viewValues,
			insert);

		if (valuesDeleter.Failed() || viewValuesDeleter.Failed())
			return B_NO_MEMORY;

		values->SetScale(_ScaleFor(source->ScaleType()));

		DataSource* copy;
		if (source->PerCPU())
			copy = source->CopyForCPU(i);
		else
			copy = source->Copy();

		ListAddDeleter<DataSource> sourceDeleter(fSources, copy, insert);
		if (sourceDeleter.Failed())
			return B_NO_MEMORY;

		BString colorName = source->Name();
		colorName << " color";
		if (state != NULL) {
			const rgb_color* color = NULL;
			ssize_t colorLength;
			if (state->FindData(colorName.String(), B_RGB_COLOR_TYPE, i,
					(const void**)&color, &colorLength) == B_OK
				&& colorLength == sizeof(rgb_color))
				copy->SetColor(*color);
		}

		valuesDeleter.Detach();
		viewValuesDeleter.Detach();
		sourceDeleter.Detach();
		insert++;
	}

#ifdef __HAIKU__
	InvalidateLayout();
#endif
	return B_OK;
}


status_t
ActivityView::RemoveDataSource(const DataSource* remove)
{
	bool removed = false;

	BAutolock _(fSourcesLock);

	while (true) {
		DataSource* source = FindDataSource(remove);
		if (source == NULL) {
			if (removed)
				break;
			return B_ENTRY_NOT_FOUND;
		}

		int32 index = fSources.IndexOf(source);
		if (index < 0)
			return B_ENTRY_NOT_FOUND;

		fSources.RemoveItemAt(index);
		delete source;
		DataHistory* values = fValues.RemoveItemAt(index);
		delete values;
		removed = true;
	}

#ifdef __HAIKU__
	InvalidateLayout();
#endif
	return B_OK;
}


void
ActivityView::RemoveAllDataSources()
{
	BAutolock _(fSourcesLock);

	fSources.MakeEmpty();
	fValues.MakeEmpty();
}


void
ActivityView::AttachedToWindow()
{
	Looper()->AddHandler(fSystemInfoHandler);
	fSystemInfoHandler->StartWatching();

	fRefreshSem = create_sem(0, "refresh sem");
	fRefreshThread = spawn_thread(&_RefreshThread, "source refresh",
		B_URGENT_DISPLAY_PRIORITY, this);
	resume_thread(fRefreshThread);

	FrameResized(Bounds().Width(), Bounds().Height());
}


void
ActivityView::DetachedFromWindow()
{
	fSystemInfoHandler->StopWatching();
	Looper()->RemoveHandler(fSystemInfoHandler);

	delete_sem(fRefreshSem);
	wait_for_thread(fRefreshThread, NULL);
}


#ifdef __HAIKU__
BSize
ActivityView::MinSize()
{
	BSize size(32, 32);
	if (fShowLegend)
		size.height = _LegendHeight();

	return size;
}
#endif


void
ActivityView::FrameResized(float /*width*/, float /*height*/)
{
	_UpdateOffscreenBitmap();
}


void
ActivityView::_UpdateOffscreenBitmap()
{
	BRect frame = _HistoryFrame();
	frame.OffsetTo(B_ORIGIN);

	if (fOffscreen != NULL && frame == fOffscreen->Bounds())
		return;

	delete fOffscreen;

	// create offscreen bitmap

	fOffscreen = new(std::nothrow) BBitmap(frame, B_BITMAP_ACCEPTS_VIEWS,
		B_RGB32);
	if (fOffscreen == NULL || fOffscreen->InitCheck() != B_OK) {
		delete fOffscreen;
		fOffscreen = NULL;
		return;
	}

	BView* view = new BView(frame, NULL, B_FOLLOW_NONE, B_SUBPIXEL_PRECISE);
	view->SetViewColor(fHistoryBackgroundColor);
	view->SetLowColor(view->ViewColor());
	fOffscreen->AddChild(view);
}


BView*
ActivityView::_OffscreenView()
{
	if (fOffscreen == NULL)
		return NULL;

	return fOffscreen->ChildAt(0);
}


void
ActivityView::MouseDown(BPoint where)
{
	int32 buttons = B_SECONDARY_MOUSE_BUTTON;
	if (Looper() != NULL && Looper()->CurrentMessage() != NULL)
		Looper()->CurrentMessage()->FindInt32("buttons", &buttons);

	if (buttons == B_PRIMARY_MOUSE_BUTTON) {
		fZoomPoint = where;
		fOriginalResolution = fDrawResolution;
		fZooming = true;
		SetMouseEventMask(B_POINTER_EVENTS);
		return;
	}

	BPopUpMenu *menu = new BPopUpMenu(B_EMPTY_STRING, false, false);
	menu->SetFont(be_plain_font);

	BMenu* additionalMenu = new BMenu(B_TRANSLATE("Additional items"));
	additionalMenu->SetFont(be_plain_font);

	SystemInfo info;
	BMenuItem* item;

	for (int32 i = 0; i < DataSource::CountSources(); i++) {
		const DataSource* source = DataSource::SourceAt(i);

		if (source->MultiCPUOnly() && info.CPUCount() == 1)
			continue;

		BMessage* message = new BMessage(kMsgToggleDataSource);
		message->AddInt32("index", i);

		item = new BMenuItem(source->Name(), message);
		if (FindDataSource(source))
			item->SetMarked(true);

		if (source->Primary())
			menu->AddItem(item);
		else
			additionalMenu->AddItem(item);
	}

	menu->AddItem(new BMenuItem(additionalMenu));
	menu->AddSeparatorItem();
	menu->AddItem(item = new BMenuItem(B_TRANSLATE("Show legend"),
		new BMessage(kMsgToggleLegend)));
	item->SetMarked(fShowLegend);

	menu->SetTargetForItems(this);
	additionalMenu->SetTargetForItems(this);

	ActivityWindow* window = dynamic_cast<ActivityWindow*>(Window());
	if (window != NULL && window->ActivityViewCount() > 1) {
		menu->AddSeparatorItem();
		BMessage* message = new BMessage(kMsgRemoveView);
		message->AddPointer("view", this);
		menu->AddItem(item = new BMenuItem(B_TRANSLATE("Remove graph"),
			message));
		item->SetTarget(window);
	}

	ConvertToScreen(&where);
	menu->Go(where, true, false, true);
}


void
ActivityView::MouseUp(BPoint where)
{
	fZooming = false;
}


void
ActivityView::MouseMoved(BPoint where, uint32 transit,
	const BMessage* dragMessage)
{
	if (!fZooming)
		return;

	int32 shift = int32(where.x - fZoomPoint.x) / 25;
	int32 resolution;
	if (shift > 0)
		resolution = fOriginalResolution << shift;
	else
		resolution = fOriginalResolution >> -shift;

	_UpdateResolution(resolution);
}


void
ActivityView::MessageReceived(BMessage* message)
{
	// if a color is dropped, use it as background
	if (message->WasDropped()) {
		rgb_color* color;
		ssize_t size;
		if (message->FindData("RGBColor", B_RGB_COLOR_TYPE, 0,
				(const void**)&color, &size) == B_OK
			&& size == sizeof(rgb_color)) {
			BPoint dropPoint = message->DropPoint();
			ConvertFromScreen(&dropPoint);

			if (_HistoryFrame().Contains(dropPoint)) {
				fHistoryBackgroundColor = *color;
				Invalidate(_HistoryFrame());
			} else {
				// check each legend color box
				BAutolock _(fSourcesLock);

				BRect legendFrame = _LegendFrame();
				for (int32 i = 0; i < fSources.CountItems(); i++) {
					BRect frame = _LegendColorFrameAt(legendFrame, i);
					if (frame.Contains(dropPoint)) {
						fSources.ItemAt(i)->SetColor(*color);
						Invalidate(_HistoryFrame());
						Invalidate(frame);
						return;
					}
				}

				if (dynamic_cast<ActivityMonitor*>(be_app) == NULL) {
					// allow background color change in the replicant only
					fLegendBackgroundColor = *color;
					SetLowColor(fLegendBackgroundColor);
					Invalidate(legendFrame);
				}
			}
			return;
		}
	}

	switch (message->what) {
		case B_ABOUT_REQUESTED:
		{
			BAboutWindow* window = new BAboutWindow(kAppName, kSignature);

			const char* authors[] = {
				"Axel Dörfler",
				NULL
			};

			window->AddCopyright(2008, "Haiku, Inc.");
			window->AddAuthors(authors);

			window->Show();

			break;
		}
		case kMsgUpdateResolution:
		{
			int32 resolution;
			if (message->FindInt32("resolution", &resolution) != B_OK)
				break;

			_UpdateResolution(resolution, false);
			break;
		}

		case kMsgTimeIntervalUpdated:
			bigtime_t interval;
			if (message->FindInt64("interval", &interval) != B_OK)
				break;

			if (interval < 10000)
				interval = 10000;

			atomic_set64(&fRefreshInterval, interval);
			break;

		case kMsgToggleDataSource:
		{
			int32 index;
			if (message->FindInt32("index", &index) != B_OK)
				break;

			const DataSource* baseSource = DataSource::SourceAt(index);
			if (baseSource == NULL)
				break;

			DataSource* source = FindDataSource(baseSource);
			if (source == NULL)
				AddDataSource(baseSource);
			else
				RemoveDataSource(baseSource);

			Invalidate();
			break;
		}

		case kMsgToggleLegend:
			fShowLegend = !fShowLegend;
			Invalidate();
			break;

		case B_MOUSE_WHEEL_CHANGED:
		{
			float deltaY = 0.0f;
			if (message->FindFloat("be:wheel_delta_y", &deltaY) != B_OK
				|| deltaY == 0.0f)
				break;

			int32 resolution = fDrawResolution;
			if (deltaY > 0)
				resolution *= 2;
			else
				resolution /= 2;

			_UpdateResolution(resolution);
			break;
		}

		default:
			BView::MessageReceived(message);
			break;
	}
}


void
ActivityView::_UpdateFrame()
{
#ifdef __HAIKU__
	if (fLegendLayoutItem == NULL || fHistoryLayoutItem == NULL)
		return;

	BRect historyFrame = fHistoryLayoutItem->Frame();
	BRect legendFrame = fLegendLayoutItem->Frame();
#else
	BRect historyFrame = Bounds();
	BRect legendFrame = Bounds();
	historyFrame.bottom -= 2 * Bounds().Height() / 3;
	legendFrame.top += Bounds().Height() / 3;
#endif
	MoveTo(historyFrame.left, historyFrame.top);
	ResizeTo(legendFrame.left + legendFrame.Width() - historyFrame.left,
		legendFrame.top + legendFrame.Height() - historyFrame.top);
}


BRect
ActivityView::_HistoryFrame() const
{
	BRect frame = Bounds();

	if (fShowLegend) {
		BRect legendFrame = _LegendFrame();
		frame.bottom = legendFrame.top - 1;
	}

	frame.InsetBy(2, 2);

	return frame;
}


float
ActivityView::_LegendHeight() const
{
	font_height fontHeight;
	GetFontHeight(&fontHeight);

	BAutolock _(fSourcesLock);

	int32 rows = (fSources.CountItems() + 1) / 2;

	int32 boldMargin = Parent()
		&& (Parent()->Flags() & B_DRAW_ON_CHILDREN) != 0 ? 2 : 0;

	return rows * (4 + ceilf(fontHeight.ascent)
		+ ceilf(fontHeight.descent) + ceilf(fontHeight.leading)) + boldMargin;
}


BRect
ActivityView::_LegendFrame() const
{
	float height;
#ifdef __HAIKU__
	if (fLegendLayoutItem != NULL)
		height = fLegendLayoutItem->Frame().Height();
	else
#endif
		height = _LegendHeight();

	BRect frame = Bounds();
	frame.bottom -= kDraggerSize;
	frame.top = frame.bottom - height;

	return frame;
}


BRect
ActivityView::_LegendFrameAt(BRect frame, int32 index) const
{
	int32 column = index & 1;
	int32 row = index / 2;
	if (column == 0) {
		// Use the full width if there is only one item
		if (fSources.CountItems() != 1)
			frame.right = frame.left + floorf(frame.Width() / 2) - 5;
	} else
		frame.left = frame.right - floorf(frame.Width() / 2) + 5;

	BAutolock _(fSourcesLock);

	int32 rows = (fSources.CountItems() + 1) / 2;
	float height = floorf((frame.Height() - 5) / rows);

	frame.top = frame.top + 5 + row * height;
	frame.bottom = frame.top + height - 1;

	return frame;
}


BRect
ActivityView::_LegendColorFrameAt(BRect frame, int32 index) const
{
	frame = _LegendFrameAt(frame, index);
	frame.InsetBy(1, 1);
	frame.right = frame.left + frame.Height();

	return frame;
}


float
ActivityView::_PositionForValue(DataSource* source, DataHistory* values,
	int64 value)
{
	int64 min = source->Minimum();
	int64 max = source->Maximum();
	if (source->AdaptiveScale()) {
		int64 adaptiveMax = int64(values->MaximumValue() * 1.2);
		if (adaptiveMax < max)
			max = adaptiveMax;
	}

	if (value > max)
		value = max;
	if (value < min)
		value = min;

	float height = _HistoryFrame().Height();
	return height - (value - min) * height / (max - min);
}


void
ActivityView::_DrawHistory()
{
	_UpdateOffscreenBitmap();

	BView* view = this;
	if (fOffscreen != NULL) {
		fOffscreen->Lock();
		view = _OffscreenView();
	}

	BRect frame = _HistoryFrame();
	BRect outerFrame = frame.InsetByCopy(-2, -2);

	// draw the outer frame
	uint32 flags = BControlLook::B_BLEND_FRAME;
	be_control_look->DrawTextControlBorder(this, outerFrame,
		outerFrame, fLegendBackgroundColor, flags);

	// convert to offscreen view if necessary
	if (view != this)
		frame.OffsetTo(B_ORIGIN);

	view->SetLowColor(fHistoryBackgroundColor);
	view->FillRect(frame, B_SOLID_LOW);

	uint32 step = 2;
	uint32 resolution = fDrawResolution;
	if (fDrawResolution > 1) {
		step = 1;
		resolution--;
	}

	// We would get a negative number of steps which isn't a good idea.
	if (frame.IntegerWidth() <= 10)
		return;

	uint32 width = frame.IntegerWidth() - 10;
	uint32 steps = width / step;
	bigtime_t timeStep = RefreshInterval() * resolution;
	bigtime_t now = system_time();

	// Draw scale
	// TODO: add second markers?

	view->SetPenSize(1);

	rgb_color scaleColor = view->LowColor();
	uint32 average = (scaleColor.red + scaleColor.green + scaleColor.blue) / 3;
	if (average < 96)
		scaleColor = tint_color(scaleColor, B_LIGHTEN_2_TINT);
	else
		scaleColor = tint_color(scaleColor, B_DARKEN_2_TINT);

	view->SetHighColor(scaleColor);
	view->StrokeLine(BPoint(frame.left, frame.top + frame.Height() / 2),
		BPoint(frame.right, frame.top + frame.Height() / 2));

	// Draw values

	view->SetPenSize(1.5);
	BAutolock _(fSourcesLock);

	for (uint32 i = fSources.CountItems(); i-- > 0;) {
		ViewHistory* viewValues = fViewValues.ItemAt(i);
		DataSource* source = fSources.ItemAt(i);
		DataHistory* values = fValues.ItemAt(i);

		viewValues->Update(values, steps, fDrawResolution, now, timeStep,
			RefreshInterval());

		if (viewValues->Start() >= (int32)steps - 1)
			continue;

		uint32 x = viewValues->Start() * step;

		bool first = true;

		view->SetHighColor(source->Color());
		view->SetLineMode(B_BUTT_CAP, B_ROUND_JOIN);
		view->MovePenTo(B_ORIGIN);

		try {
			view->BeginLineArray(steps - viewValues->Start() - 1);

			BPoint prev;

			for (uint32 j = viewValues->Start(); j < steps; x += step, j++) {
				float y = _PositionForValue(source, values,
					viewValues->ValueAt(j));

				if (first) {
					first = false;
				} else
					view->AddLine(prev, BPoint(x, y), source->Color());

				prev.Set(x, y);
			}

		} catch (std::bad_alloc&) {
			// Not enough memory to allocate the line array.
			// TODO we could try to draw using the slower but less memory
			// consuming solution using StrokeLine.
		}

		view->EndLineArray();
	}

	// TODO: add marks when an app started or quit
	view->Sync();
	if (fOffscreen != NULL) {
		fOffscreen->Unlock();
		DrawBitmap(fOffscreen, outerFrame.LeftTop());
	}
}


void
ActivityView::_UpdateResolution(int32 resolution, bool broadcast)
{
	if (resolution < 1)
		resolution = 1;
	if (resolution > 128)
		resolution = 128;

	if (resolution == fDrawResolution)
		return;

	ActivityWindow* window = dynamic_cast<ActivityWindow*>(Window());
	if (broadcast && window != NULL) {
		BMessage update(kMsgUpdateResolution);
		update.AddInt32("resolution", resolution);
		window->BroadcastToActivityViews(&update, this);
	}

	fDrawResolution = resolution;
	Invalidate();
}


void
ActivityView::Draw(BRect updateRect)
{
	_DrawHistory();

	if (!fShowLegend)
		return;

	// draw legend
	BRect legendFrame = _LegendFrame();
	if (LowUIColor() == B_NO_COLOR)
		SetLowColor(fLegendBackgroundColor);

	BAutolock _(fSourcesLock);

	font_height fontHeight;
	GetFontHeight(&fontHeight);

	for (int32 i = 0; i < fSources.CountItems(); i++) {
		DataSource* source = fSources.ItemAt(i);
		DataHistory* values = fValues.ItemAt(i);
		BRect frame = _LegendFrameAt(legendFrame, i);

		// draw color box
		BRect colorBox = _LegendColorFrameAt(legendFrame, i);
		BRect rect = colorBox;
		uint32 flags = BControlLook::B_BLEND_FRAME;
		be_control_look->DrawTextControlBorder(this, rect,
			rect, fLegendBackgroundColor, flags);
		SetHighColor(source->Color());
		FillRect(rect);

		// show current value and label
		float y = frame.top + ceilf(fontHeight.ascent);
		int64 value = values->ValueAt(values->End());
		BString text;
		source->Print(text, value);
		float width = StringWidth(text.String());

		BString label = source->Label();
		float possibleLabelWidth = frame.right - colorBox.right - 12 - width;
		if (ceilf(StringWidth(label.String())) > possibleLabelWidth)
			label = source->ShortLabel();
		TruncateString(&label, B_TRUNCATE_MIDDLE, possibleLabelWidth);

		if (be_control_look == NULL) {
			DrawString(label.String(), BPoint(6 + colorBox.right, y));
			DrawString(text.String(), BPoint(frame.right - width, y));
		} else {
			be_control_look->DrawLabel(this, label.String(),
				Parent()->ViewColor(), 0, BPoint(6 + colorBox.right, y));
			be_control_look->DrawLabel(this, text.String(),
				Parent()->ViewColor(), 0, BPoint(frame.right - width, y));
		}
	}
}


void
ActivityView::_Refresh()
{
	bigtime_t lastTimeout = system_time() - RefreshInterval();
	BMessenger target(this);

	while (true) {
		status_t status = acquire_sem_etc(fRefreshSem, 1, B_ABSOLUTE_TIMEOUT,
			lastTimeout + RefreshInterval());
		if (status == B_OK || status == B_BAD_SEM_ID)
			break;
		if (status == B_INTERRUPTED)
			continue;

		SystemInfo info(fSystemInfoHandler);
		lastTimeout += RefreshInterval();

		fSourcesLock.Lock();

		for (uint32 i = fSources.CountItems(); i-- > 0;) {
			DataSource* source = fSources.ItemAt(i);
			DataHistory* values = fValues.ItemAt(i);

			int64 value = source->NextValue(info);
			values->AddValue(info.Time(), value);
		}

		fSourcesLock.Unlock();

		target.SendMessage(B_INVALIDATE);
	}
}


/*static*/ status_t
ActivityView::_RefreshThread(void* self)
{
	((ActivityView*)self)->_Refresh();
	return B_OK;
}