/****************************************************************************
 *
 *   Copyright (c) 2020 PX4 Development Team. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name PX4 nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

#pragma once

// Console event output can be enabled if needed.
// Note: this will only print custom (PX4) events, not from common.
// Helpful for debugging and to ensure the system is not spammed with events.
// It does not print arguments.
#if 0
#include <px4_platform_common/log.h>
#define CONSOLE_PRINT_EVENT(log_level, id, str) PX4_INFO_RAW("Event 0x%08" PRIx32 ": %s\n", id, str)
#else
#define CONSOLE_PRINT_EVENT(log_level, id, str)
#endif

#include <events/events_generated.h>
#include <uORB/topics/event.h>

#include <stdint.h>

namespace events
{

namespace util
{

// source: https://gist.github.com/ruby0x1/81308642d0325fd386237cfa3b44785c
constexpr uint32_t val_32_const = 0x811c9dc5;
constexpr uint32_t prime_32_const = 0x1000193;
constexpr uint64_t val_64_const = 0xcbf29ce484222325;
constexpr uint64_t prime_64_const = 0x100000001b3;
inline constexpr uint32_t hash_32_fnv1a_const(const char *const str, const uint32_t value = val_32_const) noexcept
{
	return (str[0] == '\0') ? value : hash_32_fnv1a_const(&str[1], (value ^ uint32_t(str[0])) * prime_32_const);
}

template<typename T>
inline constexpr void fillEventArguments(uint8_t *buf, T arg)
{
	// This assumes we're on little-endian
	memcpy(buf, &arg, sizeof(T));
}

template<typename T, typename... Args>
inline constexpr void fillEventArguments(uint8_t *buf, T arg, Args... args)
{
	fillEventArguments(buf, arg);
	fillEventArguments(buf + sizeof(T), args...);
}

constexpr unsigned sizeofArguments() { return 0; }

template <typename T, typename... Args>
constexpr unsigned sizeofArguments(const T &t, const Args &... args)
{
	return sizeof(T) + sizeofArguments(args...);
}

} // namespace util


/**
 * publish/send an event
 */
void send(event_s &event);

/**
 * Generate event ID from an event name
 */
template<size_t N>
constexpr uint32_t ID(const char (&name)[N])
{
	// Note: the generated ID must match with the python generator under Tools/px4events
	uint32_t component_id = 1u << 24; // autopilot component
	return (0xffffff & util::hash_32_fnv1a_const(name)) | component_id;
}

template<typename... Args>
inline void send(uint32_t id, const LogLevels &log_levels, const char *message, Args... args)
{
	event_s e{};
	e.log_levels = ((uint8_t)log_levels.internal << 4) | (uint8_t)log_levels.external;
	e.id = id;
	static_assert(util::sizeofArguments(args...) <= sizeof(e.arguments), "Too many arguments");
	util::fillEventArguments((uint8_t *)e.arguments, args...);
	CONSOLE_PRINT_EVENT(e.log_level_external, e.id, message);
	send(e);
}

inline void send(uint32_t id, const LogLevels &log_levels, const char *message)
{
	event_s e{};
	e.log_levels = ((uint8_t)log_levels.internal << 4) | (uint8_t)log_levels.external;
	e.id = id;
	CONSOLE_PRINT_EVENT(e.log_level_external, e.id, message);
	send(e);
}

static constexpr uint16_t initial_event_sequence = 65535 - 10; // initialize with a high number so it wraps soon

} // namespace events