/** Average hook.
 *
 * @author Steffen Vogel <post@steffenvogel.de>
 * @copyright 2014-2022, Institute for Automation of Complex Power Systems, EONERC
 * @license Apache 2.0
 *********************************************************************************/

#include <bitset>
#include <cstring>

#include <villas/hook.hpp>
#include <villas/node/exceptions.hpp>
#include <villas/signal.hpp>
#include <villas/sample.hpp>

namespace villas {
namespace node {

class AverageHook : public MultiSignalHook {

protected:
	unsigned offset;

public:
	AverageHook(Path *p, Node *n, int fl, int prio, bool en = true) :
		MultiSignalHook(p, n, fl, prio, en),
		offset(0)
	{ }

	virtual void prepare()
	{
		assert(state == State::CHECKED);

		MultiSignalHook::prepare();

		/* Add averaged signal */
		auto avg_sig = std::make_shared<Signal>("average", "", SignalType::FLOAT);
		if (!avg_sig)
			throw RuntimeError("Failed to create new signal");

		signals->insert(signals->begin() + offset, avg_sig);

		state = State::PREPARED;
	}

	virtual void parse(json_t *json)
	{
		int ret;
		json_error_t err;

		assert(state != State::STARTED);

		MultiSignalHook::parse(json);

		ret = json_unpack_ex(json, &err, 0, "{ s: i }",
			"offset", &offset
		);
		if (ret)
			throw ConfigError(json, err, "node-config-hook-average");

		state = State::PARSED;
	}

	virtual Hook::Reason process(struct Sample *smp)
	{
		double avg, sum = 0;
		int n = 0;

		assert(state == State::STARTED);

		for (unsigned index : signalIndices) {
			switch (sample_format(smp, index)) {
				case SignalType::INTEGER:
					sum += smp->data[index].i;
					break;

				case SignalType::FLOAT:
					sum += smp->data[index].f;
					break;

				case SignalType::INVALID:
				case SignalType::COMPLEX:
				case SignalType::BOOLEAN:
					return Hook::Reason::ERROR; /* not supported */
			}

			n++;
		}

		avg = sum / n;

		if (offset >= smp->length)
			return Reason::ERROR;

		sample_data_insert(smp, (union SignalData *) &avg, offset, 1);

		return Reason::OK;
	}
};

/* Register hook */
static char n[] = "average";
static char d[] = "Calculate average over some signals";
static HookPlugin<AverageHook, n , d, (int) Hook::Flags::PATH | (int) Hook::Flags::NODE_READ | (int) Hook::Flags::NODE_WRITE> p;

} /* namespace node */
} /* namespace villas */