/** The internal datastructure for a sample of simulation data.
 *
 * @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 <atomic>

#include <cstddef>
#include <cstdlib>
#include <cstdio>
#include <ctime>

#include <villas/log.hpp>
#include <villas/signal.hpp>
#include <villas/signal_list.hpp>

/** The length of a sample datastructure with \p values values in bytes. */
#define SAMPLE_LENGTH(len)	(sizeof(struct Sample) + SAMPLE_DATA_LENGTH(len))

/** The length of a sample data portion of a sample datastructure with \p values values in bytes. */
#define SAMPLE_DATA_LENGTH(len)	((len) * sizeof(double))

/** The number of values in a sample datastructure. */
#define SAMPLE_NUMBER_OF_VALUES(len)	((len) / sizeof(double))

/** The offset to the beginning of the data section. */
#define SAMPLE_DATA_OFFSET(smp)	((char *) (smp) + offsetof(struct Sample, data))

namespace villas {
namespace node {

/* Forward declarations */
struct Pool;

/** Parts of a sample that can be serialized / de-serialized by the IO formats */
enum class SampleFlags {
	HAS_TS_ORIGIN	= (1 << 0), /**< Include origin timestamp in output. */
	HAS_TS_RECEIVED	= (1 << 1), /**< Include receive timestamp in output. */
	HAS_OFFSET	= (1 << 2), /**< Include offset (received - origin timestamp) in output. */
	HAS_SEQUENCE	= (1 << 3), /**< Include sequence number in output. */
	HAS_DATA	= (1 << 4), /**< Include values in output. */

	HAS_TS		= HAS_TS_ORIGIN | HAS_TS_RECEIVED, /**< Include origin timestamp in output. */
	HAS_ALL		= (1 << 5) - 1, /**< Enable all output options. */

	IS_FIRST	= (1 << 16), /**< This sample is the first of a new simulation case */
	IS_LAST		= (1 << 17) /**< This sample is the last of a running simulation case */
};

struct Sample {
	uint64_t sequence;			/**< The sequence number of this sample. */
	unsigned length;			/**< The number of values in sample::values which are valid. */
	unsigned capacity;			/**< The number of values in sample::values for which memory is reserved. */
	int flags;				/**< Flags are used to store binary properties of a sample. */

	SignalList::Ptr signals;		/**< The list of signal descriptors. */

	std::atomic<int> refcnt;		/**< Reference counter. */
	ptrdiff_t pool_off;			/**< This sample belongs to this memory pool (relative pointer). See sample_pool(). */

	/** All timestamps are seconds / nano seconds after 1.1.1970 UTC */
	struct {
		struct timespec origin;		/**< The point in time when this data was sampled. */
		struct timespec received;	/**< The point in time when this data was received. */
	} ts;

	/** The sample signal values.
	 *
	 * This variable length array (VLA) extends over the end of struct Sample.
	 * Make sure that pointers to struct Sample point to memory blocks of adequate size.
	 * Use the SAMPLE_LENGTH() macro to calculate the required size.
	 *
	 * Metadata describing the details of signal values (such as name, unit, data type and more)
	 * are stored in the struct Sample::signals list. Each entry in this list corresponedents
	 * to an entry in the struct Sample::data array.
	 */
	union SignalData data[];
};

#define SAMPLE_NON_POOL PTRDIFF_MIN

/** Get the address of the pool to which the sample belongs. */
#define sample_pool(s) ((s)->pool_off == SAMPLE_NON_POOL ? nullptr : (struct Pool *) ((char *) (s) + (s)->pool_off))

struct Sample * sample_alloc(struct Pool *p);

struct Sample * sample_alloc_mem(int capacity);

int sample_init(struct Sample *s);

struct Sample * sample_clone(struct Sample *smp);

void sample_free(struct Sample *s);

/** Request \p cnt samples from memory pool \p p and initialize them.
 *  The reference count will already be set to 1.
 *  Use the sample_incref() function to increase it. */
int sample_alloc_many(struct Pool *p, struct Sample *smps[], int cnt);

/** Release an array of samples back to their pools */
void sample_free_many(struct Sample *smps[], int cnt);

/** Increase reference count of sample */
int sample_incref(struct Sample *s);

/** Decrease reference count and release memory if last reference was held. */
int sample_decref(struct Sample *s);

int sample_copy(struct Sample *dst, const struct Sample *src);

/** Dump all details about a sample to debug log */
void sample_dump(villas::Logger logger, struct Sample *s);

/** Compare two samples */
int sample_cmp(struct Sample *a, struct Sample *b, double epsilon, int flags);

int sample_clone_many(struct Sample *dsts[], const struct Sample * const srcs[], int cnt);
int sample_copy_many(struct Sample * const dsts[], const struct Sample * const srcs[], int cnt);
int sample_incref_many(struct Sample * const smps[], int cnt);
int sample_decref_many(struct Sample * const smps[], int cnt);

enum SignalType sample_format(const struct Sample *s, unsigned idx);

void sample_data_insert(struct Sample *smp, const union SignalData *src, size_t offset, size_t len);
void sample_data_remove(struct Sample *smp, size_t offset, size_t len);

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