// Copyright Epic Games, Inc. All Rights Reserved.

#pragma once

#include <spdlog/sinks/sink.h>
#include <zencore/zencore.h>
#include <zenhttp/httpclient.h>
#include <zentelemetry/otlpencoder.h>
#include <zentelemetry/otlptrace.h>

#if ZEN_WITH_OTEL

namespace zen::logging {

/**
 * OTLP/HTTP sink for spdlog
 *
 * Sends log messages and traces to an OpenTelemetry collector via OTLP over HTTP
 */

class OtelHttpProtobufSink : public spdlog::sinks::sink
{
public:
	// Note that this URI should be the base URI of the OTLP HTTP endpoint, e.g.
	// "http://otel-collector:4318"
	OtelHttpProtobufSink(const std::string_view& Uri);
	~OtelHttpProtobufSink();

	OtelHttpProtobufSink(const OtelHttpProtobufSink&) = delete;
	OtelHttpProtobufSink& operator=(const OtelHttpProtobufSink&) = delete;

private:
	virtual void log(const spdlog::details::log_msg& Msg) override;
	virtual void flush() override;
	virtual void set_pattern(const std::string& pattern) override { ZEN_UNUSED(pattern); }
	virtual void set_formatter(std::unique_ptr<spdlog::formatter> sink_formatter) override { ZEN_UNUSED(sink_formatter); }

	void RecordSpans(zen::otel::TraceId Trace, std::span<const zen::otel::Span*> Spans);

	// This is just a thin wrapper to call back into the sink while participating in
	// reference counting from the OTEL trace back-end
	class TraceRecorder : public zen::otel::TraceRecorder
	{
	public:
		TraceRecorder(OtelHttpProtobufSink* InSink) : m_Sink(InSink) {}

	private:
		TraceRecorder(const TraceRecorder&) = delete;
		TraceRecorder& operator=(const TraceRecorder&) = delete;

		virtual void RecordSpans(zen::otel::TraceId Trace, std::span<const zen::otel::Span*> Spans) override;

		OtelHttpProtobufSink* m_Sink;
	};

	HttpClient		   m_OtelHttp;
	OtlpEncoder		   m_Encoder;
	Ref<TraceRecorder> m_TraceRecorder;
};

}  // namespace zen::logging

#endif