/*
 * Copyright 2018-2022, Andrew Lindesay <apl@lindesay.co.nz>.
 * All rights reserved. Distributed under the terms of the MIT License.
 */


#include "ProcessCoordinator.h"

#include <AutoLocker.h>
#include <Catalog.h>
#include <StringFormat.h>
#include <Uuid.h>

#include "Logger.h"


#undef B_TRANSLATION_CONTEXT
#define B_TRANSLATION_CONTEXT "ProcessCoordinator"

#define LOCK_TIMEOUT_MICROS (1000 * 1000)

// These are keys that are used to store the ProcessCoordinatorState data into
// a BMessage instance.

#define KEY_PROCESS_COORDINATOR_IDENTIFIER	"processCoordinatorIdentifier"
#define KEY_PROGRESS						"progress"
#define KEY_MESSAGE							"message"
#define KEY_IS_RUNNING						"isRunning"
#define KEY_ERROR_STATUS					"errorStatus"


// #pragma mark - ProcessCoordinatorState implementation


ProcessCoordinatorState::ProcessCoordinatorState(BMessage* from)
{
	if (from->FindString(KEY_PROCESS_COORDINATOR_IDENTIFIER,
			&fProcessCoordinatorIdentifier) != B_OK) {
		HDFATAL("unable to find the key [%s]",
			KEY_PROCESS_COORDINATOR_IDENTIFIER);
	}

	if (from->FindFloat(KEY_PROGRESS, &fProgress) != B_OK) {
		HDFATAL("unable to find the key [%s]", KEY_PROGRESS);
	}

	if (from->FindString(KEY_MESSAGE, &fMessage) != B_OK) {
		HDFATAL("unable to find the key [%s]", KEY_MESSAGE);
	}

	if (from->FindBool(KEY_IS_RUNNING, &fIsRunning) != B_OK) {
		HDFATAL("unable to find the key [%s]", KEY_IS_RUNNING);
	}

	int64 errorStatusNumeric;
	if (from->FindInt64(KEY_ERROR_STATUS, &errorStatusNumeric) != B_OK) {
		HDFATAL("unable to find the key [%s]", KEY_ERROR_STATUS);
	}
	fErrorStatus = static_cast<status_t>(errorStatusNumeric);
}


ProcessCoordinatorState::ProcessCoordinatorState(
	const ProcessCoordinator* processCoordinator, float progress,
	const BString& message, bool isRunning, status_t errorStatus)
	:
	fProcessCoordinatorIdentifier(processCoordinator->Identifier()),
	fProgress(progress),
	fMessage(message),
	fIsRunning(isRunning),
	fErrorStatus(errorStatus)
{
}


ProcessCoordinatorState::~ProcessCoordinatorState()
{
}


const BString
ProcessCoordinatorState::ProcessCoordinatorIdentifier() const
{
	return fProcessCoordinatorIdentifier;
}


float
ProcessCoordinatorState::Progress() const
{
	return fProgress;
}


BString
ProcessCoordinatorState::Message() const
{
	return fMessage;
}


bool
ProcessCoordinatorState::IsRunning() const
{
	return fIsRunning;
}


status_t
ProcessCoordinatorState::ErrorStatus() const
{
	return fErrorStatus;
}


status_t
ProcessCoordinatorState::Archive(BMessage* into, bool deep) const
{
	status_t result = B_OK;
	if (result == B_OK) {
		result = into->AddString(KEY_PROCESS_COORDINATOR_IDENTIFIER,
			fProcessCoordinatorIdentifier);
	}
	if (result == B_OK)
		result = into->AddFloat(KEY_PROGRESS, fProgress);
	if (result == B_OK)
		result = into->AddString(KEY_MESSAGE, fMessage);
	if (result == B_OK)
		result = into->AddBool(KEY_IS_RUNNING, fIsRunning);
	if (result == B_OK)
		result = into->AddInt64(KEY_ERROR_STATUS, static_cast<int64>(fErrorStatus));
	return result;
}


// #pragma mark - ProcessCoordinator implementation


ProcessCoordinator::ProcessCoordinator(const char* name, BMessage* message)
	:
	fName(name),
	fLock(),
	fCoordinateAndCallListenerRerun(false),
	fCoordinateAndCallListenerRerunLock(),
	fListener(NULL),
	fMessage(message),
	fWasStopped(false),
	fIdentifier(BUuid().ToString())
{
}


ProcessCoordinator::~ProcessCoordinator()
{
	AutoLocker<BLocker> locker(&fLock);
	for (int32 i = 0; i < fNodes.CountItems(); i++) {
		AbstractProcessNode* node = fNodes.ItemAt(i);
		node->Process()->SetListener(NULL);
		delete node;
	}
	delete fMessage;
}

const BString&
ProcessCoordinator::Identifier() const
{
	return fIdentifier;
}


void
ProcessCoordinator::SetListener(ProcessCoordinatorListener* listener)
{
	fListener = listener;
}


void
ProcessCoordinator::AddNode(AbstractProcessNode* node)
{
	AutoLocker<BLocker> locker(&fLock);
	fNodes.AddItem(node);
	node->SetListener(this);
	node->Process()->SetListener(this);
}


void
ProcessCoordinator::ProcessChanged()
{
	_CoordinateAndCallListener();
}


bool
ProcessCoordinator::IsRunning()
{
	AutoLocker<BLocker> locker(&fLock);
	for (int32 i = 0; i < fNodes.CountItems(); i++) {
		AbstractProcessNode* node = fNodes.ItemAt(i);
		if (node->IsRunning())
			return true;
	}

	return false;
}


void
ProcessCoordinator::Start()
{
	_CoordinateAndCallListener();
}


void
ProcessCoordinator::RequestStop()
{
	AutoLocker<BLocker> locker(&fLock);
	if (!fWasStopped) {
		fWasStopped = true;
		HDINFO("[Coordinator] will stop process coordinator");
		for (int32 i = 0; i < fNodes.CountItems(); i++) {
			AbstractProcessNode* node = fNodes.ItemAt(i);
			HDINFO("[Coordinator] stopping process [%s]",
				node->Process()->Name());
			node->RequestStop();
		}
	}
}


status_t
ProcessCoordinator::ErrorStatus()
{
	AutoLocker<BLocker> locker(&fLock);
	for (int32 i = 0; i < fNodes.CountItems(); i++) {
		status_t result = fNodes.ItemAt(i)->Process()->ErrorStatus();

		if (result != B_OK)
			return result;
	}

	return B_OK;
}


float
ProcessCoordinator::Progress()
{
	AutoLocker<BLocker> locker(&fLock);
	float result = 0.0f;

	if (!fWasStopped) {
		int32 count = fNodes.CountItems();

		// if there is only one then return it's value directly because this
		// allows for the indeterminate state of -1.

		if (count == 1)
			result = fNodes.ItemAt(0)->Process()->Progress();
		else {
			float progressPerNode = 1.0f / ((float) count);

			for (int32 i = count - 1; i >= 0; i--) {
				AbstractProcess* process = fNodes.ItemAt(i)->Process();

				switch(process->ProcessState()) {
					case PROCESS_INITIAL:
						break;
					case PROCESS_RUNNING:
						result += (progressPerNode * fmaxf(
							0.0f, fminf(1.0, process->Progress())));
						break;
					case PROCESS_COMPLETE:
						result += progressPerNode;
						break;
				}
			}
		}
	}
	return result;
}


const BString&
ProcessCoordinator::Name() const
{
	return fName;
}


BMessage*
ProcessCoordinator::Message() const
{
	return fMessage;
}


BString
ProcessCoordinator::_CreateStatusMessage()
{
	// work through the nodes and take a description from the first one.  If
	// there are others present then use a 'plus X others' suffix.  Go backwards
	// through the processes so that the most recent activity is shown first.

	BString firstProcessDescription;
	uint32 additionalRunningProcesses = 0;

	for (int32 i = fNodes.CountItems() - 1; i >= 0; i--) {
		AbstractProcess* process = fNodes.ItemAt(i)->Process();
		if (process->ProcessState() == PROCESS_RUNNING) {
			if (firstProcessDescription.IsEmpty()) {
				if (strlen(process->Description()) != 0)
					firstProcessDescription = process->Description();
				else
					additionalRunningProcesses++;
			}
			else
				additionalRunningProcesses++;
		}
	}

	if (firstProcessDescription.IsEmpty())
		return "???";

	if (additionalRunningProcesses == 0)
		return firstProcessDescription;

	static BStringFormat format(B_TRANSLATE(
		"%FIRST_PROCESS_DESCRIPTION% +"
		"{0, plural, one{# process} other{# processes}}"));
	BString result;
	format.Format(result, additionalRunningProcesses);
	result.ReplaceAll("%FIRST_PROCESS_DESCRIPTION%", firstProcessDescription);

	return result;
}


/*! This method assumes that a lock is held on the coordinator. */

ProcessCoordinatorState
ProcessCoordinator::_CreateStatus()
{
	return ProcessCoordinatorState(
		this, Progress(), _CreateStatusMessage(), IsRunning(), ErrorStatus());
}


/*! This will try to obtain the lock and if it cannot obtain the lock then
    it will flag that when the coordinator has finished its current
    coordination, it should initiate another coordination.
 */
void
ProcessCoordinator::_CoordinateAndCallListener()
{
	if (fLock.LockWithTimeout(LOCK_TIMEOUT_MICROS) != B_OK) {
		HDDEBUG("[Coordinator] would coordinate nodes, but coordination is "
			"in progress - will defer");
		AutoLocker<BLocker> locker(&fCoordinateAndCallListenerRerunLock);
		fCoordinateAndCallListenerRerun = true;
		return;
	}

	ProcessCoordinatorState state = _Coordinate();

	if (fListener != NULL)
		fListener->CoordinatorChanged(state);

	fLock.Unlock();

	bool coordinateAndCallListenerRerun = false;

	{
		AutoLocker<BLocker> locker(&fCoordinateAndCallListenerRerunLock);
		coordinateAndCallListenerRerun = fCoordinateAndCallListenerRerun;
		fCoordinateAndCallListenerRerun = false;
	}

	if (coordinateAndCallListenerRerun) {
		HDDEBUG("[Coordinator] will run deferred coordination");
		_CoordinateAndCallListener();
	}
}


ProcessCoordinatorState
ProcessCoordinator::_Coordinate()
{
	HDTRACE("[Coordinator] will coordinate nodes");
	AutoLocker<BLocker> locker(&fLock);
	_StopSuccessorNodesToErroredOrStoppedNodes();

	// go through the nodes and find those that are still to be run and
	// for which the preconditions are met to start.
	for (int32 i = 0; i < fNodes.CountItems(); i++) {
		AbstractProcessNode* node = fNodes.ItemAt(i);

		if (node->Process()->ProcessState() == PROCESS_INITIAL) {
			if (node->AllPredecessorsComplete())
				node->Start();
			else {
				HDTRACE("[Coordinator] all predecessors not complete -> "
					"[%s] not started", node->Process()->Name());
			}
		} else {
			HDTRACE("[Coordinator] process [%s] running or complete",
				node->Process()->Name());
		}
	}

	return _CreateStatus();
}


/*! This method assumes that a lock is held on the coordinator. */

void
ProcessCoordinator::_StopSuccessorNodesToErroredOrStoppedNodes()
{
	for (int32 i = 0; i < fNodes.CountItems(); i++) {
		AbstractProcessNode* node = fNodes.ItemAt(i);
		AbstractProcess* process = node->Process();

		if (process->WasStopped() || process->ErrorStatus() != B_OK)
			_StopSuccessorNodes(node);
	}
}


/*! This method assumes that a lock is held on the coordinator. */

void
ProcessCoordinator::_StopSuccessorNodes(AbstractProcessNode* predecessorNode)
{
	for (int32 i = 0; i < predecessorNode->CountSuccessors(); i++) {
		AbstractProcessNode* node = predecessorNode->SuccessorAt(i);
		AbstractProcess* process = node->Process();

		if (process->ProcessState() == PROCESS_INITIAL) {
			HDDEBUG("[Coordinator] [%s] (failed) --> [%s] (stopping)",
				predecessorNode->Process()->Name(), process->Name());
			node->RequestStop();
			_StopSuccessorNodes(node);
		}
	}
}


int32
ProcessCoordinator::_CountNodesCompleted()
{
	int32 nodesCompleted = 0;
	for (int32 i = 0; i < fNodes.CountItems(); i++) {
		AbstractProcess *process = fNodes.ItemAt(i)->Process();
		if (process->ProcessState() == PROCESS_COMPLETE)
			nodesCompleted++;
	}
	return nodesCompleted;
}


BString
ProcessCoordinator::LogReport()
{
	BString result;
	AutoLocker<BLocker> locker(&fLock);

	for (int32 i = 0; i < fNodes.CountItems(); i++) {
		if (0 != result.Length())
			result.Append("\n");
		AbstractProcessNode* node = fNodes.ItemAt(i);
		result.Append(node->LogReport());
	}

	return result;
}