/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
 * Copyright (C) 2018, Google Inc.
 *
 * Logging infrastructure
 */

#pragma once

#include <atomic>
#include <sstream>
#include <string_view>

#include <libcamera/base/private.h>

#include <libcamera/base/class.h>
#include <libcamera/base/utils.h>

namespace libcamera {

enum LogSeverity {
	LogInvalid = -1,
	LogDebug = 0,
	LogInfo,
	LogWarning,
	LogError,
	LogFatal,
};

class LogCategory
{
public:
	static LogCategory *create(std::string_view name);

	const std::string &name() const { return name_; }
	LogSeverity severity() const { return severity_.load(std::memory_order_relaxed); }
	void setSeverity(LogSeverity severity) { severity_.store(severity, std::memory_order_relaxed); }

	static const LogCategory &defaultCategory();

private:
	friend class Logger;
	explicit LogCategory(std::string_view name);

	const std::string name_;

	std::atomic<LogSeverity> severity_;
	static_assert(decltype(severity_)::is_always_lock_free);
};

#define LOG_DECLARE_CATEGORY(name)					\
extern const LogCategory &_LOG_CATEGORY(name)();

#define LOG_DEFINE_CATEGORY(name)					\
LOG_DECLARE_CATEGORY(name)						\
const LogCategory &_LOG_CATEGORY(name)()				\
{									\
	/* The instance will be deleted by the Logger destructor. */	\
	static LogCategory *category = LogCategory::create(#name);	\
	return *category;						\
}

class LogMessage
{
public:
	LogMessage(const char *fileName, unsigned int line,
		   const LogCategory &category, LogSeverity severity,
		   std::string prefix = {});
	~LogMessage();

	std::ostream &stream() { return msgStream_; }

	const utils::time_point &timestamp() const { return timestamp_; }
	LogSeverity severity() const { return severity_; }
	const LogCategory &category() const { return category_; }
	const std::string &fileInfo() const { return fileInfo_; }
	const std::string &prefix() const { return prefix_; }
	const std::string msg() const { return msgStream_.str(); }

private:
	LIBCAMERA_DISABLE_COPY_AND_MOVE(LogMessage)

	std::ostringstream msgStream_;
	const LogCategory &category_;
	LogSeverity severity_;
	utils::time_point timestamp_;
	std::string fileInfo_;
	std::string prefix_;
};

class Loggable
{
public:
	virtual ~Loggable();

protected:
	virtual std::string logPrefix() const = 0;

	LogMessage _log(const LogCategory *category, LogSeverity severity,
			const char *fileName = __builtin_FILE(),
			unsigned int line = __builtin_LINE()) const;
};

LogMessage _log(const LogCategory *category, LogSeverity severity,
		const char *fileName = __builtin_FILE(),
		unsigned int line = __builtin_LINE());

#ifndef __DOXYGEN__
#define _LOG_CATEGORY(name) logCategory##name

#define _LOG1(severity) \
	_log(nullptr, Log##severity).stream()
#define _LOG2(category, severity) \
	_log(&_LOG_CATEGORY(category)(), Log##severity).stream()

/*
 * Expand the LOG() macro to _LOG1() or _LOG2() based on the number of
 * arguments.
 */
#define _LOG_MACRO(_1, _2, NAME, ...) NAME
#define LOG(...) _LOG_MACRO(__VA_ARGS__, _LOG2, _LOG1)(__VA_ARGS__)
#else /* __DOXYGEN___ */
#define LOG(category, severity)
#endif /* __DOXYGEN__ */

#ifndef NDEBUG
#define ASSERT(condition) static_cast<void>(({                          \
	if (!(condition))                                               \
		LOG(Fatal) << "assertion \"" #condition "\" failed in " \
			   << __func__ << "()";                         \
}))
#else
#define ASSERT(condition) static_cast<void>(false && (condition))
#endif

} /* namespace libcamera */
