VILLASnode/include/villas/format.hpp

/** Read / write sample data in different formats.
 *
 * @file
 * @author Steffen Vogel <post@steffenvogel.de>
 * @copyright 2014-2022, Institute for Automation of Complex Power Systems, EONERC
 * @license Apache 2.0
 *********************************************************************************/

#pragma once

#include <memory>

#include <villas/list.hpp>
#include <villas/plugin.hpp>
#include <villas/sample.hpp>
#include <villas/signal_list.hpp>

namespace villas {
namespace node {

/* Forward declarations */
class FormatFactory;

class Format {

	friend FormatFactory;


public:
	using Ptr = std::unique_ptr<Format>;

protected:

	int flags;			/**< A set of flags which is automatically used. */
	int real_precision;		/**< Number of digits used for floatint point numbers */

	Logger logger;

	struct {
		char *buffer;
		size_t buflen;
	} in, out;

	SignalList::Ptr signals;	/**< Signal meta data for parsed samples by Format::scan() */

public:
	Format(int fl);

	virtual
	~Format();

	const SignalList::Ptr getSignals() const
	{
		return signals;
	}

	int getFlags() const
	{
		return flags;
	}

	void start(const SignalList::Ptr sigs, int fl = (int) SampleFlags::HAS_ALL);
	void start(const std::string &dtypes, int fl = (int) SampleFlags::HAS_ALL);

	virtual
	void start()
	{ }

	virtual
	void parse(json_t *json);

	virtual
	int print(FILE *f, const struct Sample * const smps[], unsigned cnt);

	virtual
	int scan(FILE *f, struct Sample * const smps[], unsigned cnt);

	/** Print \p cnt samples from \p smps into buffer \p buf of length \p len.
	 *
	 * @param buf[out]	The buffer which should be filled with serialized data.
	 * @param len[in]	The length of the buffer \p buf.
	 * @param rbytes[out]	The number of bytes which have been written to \p buf. Ignored if nullptr.
	 * @param smps[in]	The array of pointers to samples.
	 * @param cnt[in]	The number of pointers in the array \p smps.
	 *
	 * @retval >=0		The number of samples from \p smps which have been written into \p buf.
	 * @retval <0		Something went wrong.
	 */
	virtual
	int sprint(char *buf, size_t len, size_t *wbytes, const struct Sample * const smps[], unsigned cnt) = 0;

	/** Parse samples from the buffer \p buf with a length of \p len bytes.
	 *
	 * @param buf[in]	The buffer of data which should be parsed / de-serialized.
	 * @param len[in]	The length of the buffer \p buf.
	 * @param rbytes[out]	The number of bytes which have been read from \p buf.
	 * @param smps[out]	The array of pointers to samples.
	 * @param cnt[in]	The number of pointers in the array \p smps.
	 *
	 * @retval >=0		The number of samples which have been parsed from \p buf and written into \p smps.
	 * @retval <0		Something went wrong.
	 */
	virtual
	int sscan(const char *buf, size_t len, size_t *rbytes, struct Sample * const smps[], unsigned cnt) = 0;

	/* Wrappers for sending a (un)parsing single samples */

	int print(FILE *f, const struct Sample *smp)
	{
		return print(f, &smp, 1);
	}

	int scan(FILE *f, struct Sample *smp)
	{
		return scan(f, &smp, 1);
	}

	int sprint(char *buf, size_t len, size_t *wbytes, const struct Sample *smp)
	{
		return sprint(buf, len, wbytes, &smp, 1);
	}

	int sscan(const char *buf, size_t len, size_t *rbytes, struct Sample *smp)
	{
		return sscan(buf, len, rbytes, &smp, 1);
	}
};

class BinaryFormat : public Format {

public:
	using Format::Format;
};

class FormatFactory : public plugin::Plugin {

public:
	using plugin::Plugin::Plugin;

	virtual
	Format * make() = 0;

	static
	Format * make(json_t *json);

	static
	Format * make(const std::string &format);

	virtual
	void init(Format *f)
	{
		f->logger = getLogger();
	}

	virtual
	std::string getType() const
	{
		return "format";
	}

	virtual
	bool isHidden() const
	{
		return false;
	}
};

template <typename T, const char *name, const char *desc, int flags = 0>
class FormatPlugin : public FormatFactory {

public:
	using FormatFactory::FormatFactory;

	virtual Format * make()
	{
		auto *f = new T(flags);

		init(f);

		return f;
	}

	virtual
	std::string getName() const
	{
		return name;
	}

	virtual
	std::string getDescription() const
	{
		return desc;
	}
};

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