#include "AnimQueue.h"

FlxAnimStep FlxAnimQueueDecoder::ReadStep() {
	FlxAnimStep result;
	result.Hash = Decoder.read_uint64();
	result.Body = Decoder.read_string_view();
	return result;
}

FlxAnimField FlxAnimStepDecoder::ReadField() {
	FlxAnimField result;
	result.Name = Decoder.read_string_view();
	result.Persistent = Decoder.read_bool();
	result.Type = (ElxAnimValueType)Decoder.read_uint8();
	switch (result.Type) {
		case ElxAnimValueType::STRING: {
			result.S = Decoder.read_string_view();
			break;
		}
		case ElxAnimValueType::NUMBER: {
			result.X = Decoder.read_double();
			break;
		}
		case ElxAnimValueType::BOOLEAN: {
			result.X = Decoder.read_bool() ? 1.0 : 0.0;
			break;
		}
		case ElxAnimValueType::XYZ: {
			result.X = Decoder.read_double();
			result.Y = Decoder.read_double();
			result.Z = Decoder.read_double();
			break;
		}
		default: {
			Decoder.set_at_eof();
			result.Type = ElxAnimValueType::BOOLEAN;
			result.X = 0;
			break;
		}
	}
	return result;
}

FString FlxAnimQueueDecoder::DebugString(std::string_view queue) {
	FString result;
	FlxAnimQueueDecoder decoder(queue);
	while (!decoder.AtEOF()) {
		FlxAnimStep step = decoder.ReadStep();
		FString stepdebug = FlxAnimStepDecoder::DebugString(step);
		result.Appendf(TEXT("%s\n"), *stepdebug);
	}
	return result;
}

FString FlxAnimStepDecoder::DebugString(const FlxAnimStep& step) {
	FString result;
	FlxAnimStepDecoder decoder(step);
	bool first = true;
	while (!decoder.AtEOF()) {
		FlxAnimField field = decoder.ReadField();
		if (!first) {
			result.Append(TEXT(" "));
		}
		result.Append(FString(field.Name.size(), (const UTF8CHAR*)field.Name.data()));
		result.Append(field.Persistent ? TEXT("=") : TEXT(":"));
		switch (field.Type) {
		case ElxAnimValueType::STRING:
			result.Append(FString(field.S.size(), (const UTF8CHAR*)field.S.data()));
			break;
		case ElxAnimValueType::NUMBER:
			result.Appendf(TEXT("%lf"), field.X);
			break;
		case ElxAnimValueType::BOOLEAN:
			result.Append((field.X) == 1.0 ? TEXT("true") : TEXT("false"));
			break;
		case ElxAnimValueType::XYZ:
			result.Appendf(TEXT("%lf,%lf,%lf"), field.X, field.Y, field.Z);
			break;
		}
		first = false;
	}
	return result;
}


FlxAnimTracker::FlxAnimTracker() {
	AQ.Empty();
	FirstSeqno = 0;
	HashToSeqno.Empty();
	UnstartedSeqno = 0;
	PlaybackMode = ElxAnimPlaybackMode::INVALID;
	AbortedHashes.Empty();
}

void FlxAnimTracker::Update(std::string_view encqueue) {
	// Check for an exact match.  If the most recent entry
	// in encqueue has the same hash as the most recent
	// entry in AQ, then that's an exact match.   Or,
	// if both are empty, that's also an exact match.
	// In case of exact match, abort early, there's no
	// further work needed.
	//
	if (encqueue.empty()) {
		if (AQ.IsEmpty()) {
			return;
		}
	} else {
		if (!AQ.IsEmpty()) {
			FlxStringDecoder qdecoder(encqueue);
			uint64 hash = qdecoder.read_uint64();
			if (hash == AQ.Last().Hash) {
				return;
			}
		}
	}

	// Search for a Luprex animation record that matches
	// something that we already have.  Yields the sequence
	// number of the most recent matching record.
	//
	// At the same time, push all non-matching records
	// after the matching record onto a stack of new records.
	//
	FlxAnimQueueDecoder decoder(encqueue);
	TArray<FlxAnimStep> newsteps;
	int32 matchingseqno = -1;
	while (!decoder.AtEOF()) {
		FlxAnimStep step = decoder.ReadStep();
		int32* stepseq = HashToSeqno.Find(step.Hash);
		if (stepseq == nullptr) {
			newsteps.Emplace(step);
		} else {
			matchingseqno = *stepseq;
			break;
		}
	}

	// Remove all animations after the most recent matching
	// record.  If we remove a 'started' animation, add that
	// animation to the list of aborted animations.
	// 
	int32 nremove = (FirstSeqno + AQ.Num()) - (matchingseqno + 1);
	check((nremove >= 0) && (nremove <= AQ.Num()));
	for (int32 i = 0; i < nremove; i++) {
		uint64 lasthash = AQ.Last().Hash;
		int32 seqno = FirstSeqno + AQ.Num() - 1;
		HashToSeqno.Remove(lasthash);
		if (seqno < UnstartedSeqno) {
			AbortedHashes.Emplace(lasthash);
		}
		AQ.PopLast();
	}

	// If we aborted a 'started' animation, we have to fix
	// up the Unstarted animation pointer.
	// 
	// Note: this could leave the Unstarted pointer at
	// seqno less than FirstSeqno.  We will fix that state
	// of affairs up later.
	//
	if (UnstartedSeqno > (FirstSeqno + AQ.Num())) {
		UnstartedSeqno = matchingseqno;
		PlaybackMode = ElxAnimPlaybackMode::BLEND_TO_FINAL;
	}

	// Transfer the new animations onto the queue.
	//
	while (!newsteps.IsEmpty()) {
		FlxAnimStep step = newsteps.Pop();
		int32 seqno = FirstSeqno + AQ.Num();
		AQ.EmplaceLast(step.Hash, step.Body);
		HashToSeqno.Emplace(step.Hash, seqno);
	}

	// If there are too many animations in AQ, discard
	// any very old ones.
	//
	if (AQ.Num() > 10) {
		int ndiscard = AQ.Num() - 10;
		for (int i = 0; i < ndiscard; i++) {
			uint64 hash = AQ.First().Hash;
			HashToSeqno.Remove(hash);
			AQ.PopFirst();
			FirstSeqno += 1;
		}
	}

	// If UnstartedSeqno is before the live range,
	// then the whole queue has to be replayed.  Don't
	// do that: just fast skip to the end.
	//
	if (UnstartedSeqno <= FirstSeqno) {
		if (AQ.Num() == 0) {
			UnstartedSeqno = FirstSeqno;
		} else {
			UnstartedSeqno = FirstSeqno + AQ.Num() - 1;
		}
		PlaybackMode = ElxAnimPlaybackMode::WARP_TO_FINAL;
	}
}

TArray<uint64> FlxAnimTracker::GetAborted() {
	TArray<uint64> result;
	result = std::move(AbortedHashes);
	AbortedHashes.Empty();
	return result;
}

ElxAnimPlaybackMode FlxAnimTracker::GetNextStep(FlxAnimStoredStep &step) {
	int offset = UnstartedSeqno - FirstSeqno;
	if (offset < AQ.Num()) {
		step = AQ[offset];
		return PlaybackMode;
	} else {
		step.Hash = 0;
		step.Body = "";
		return ElxAnimPlaybackMode::INVALID;
	}
}

void FlxAnimTracker::StartedStep(uint64 hash) {
	int offset = UnstartedSeqno - FirstSeqno;
	check(offset < AQ.Num());
	check(AQ[offset].Hash == hash);
	UnstartedSeqno += 1;
	PlaybackMode = ElxAnimPlaybackMode::START_ANIMATION;
}