#pragma once

#include "CoreMinimal.h"
#include "Dom/JsonObject.h"

// One emission. Call sites fill Name (from TelemetryEvents) and Payload; the subsystem stamps the envelope.
struct SALTYCORE_API FTelemetryEvent
{
	FName Name;
	TSharedPtr<FJsonObject> Payload;
};

// Stamped by the subsystem onto every event. Serialised with snake_case keys; see Telemetry::ToJsonLine.
struct SALTYCORE_API FTelemetryEnvelope
{
	int32 SchemaVersion = 1;
	FGuid EventId;               // unique per emission, for de-duplication
	FDateTime TimestampUtc;
	float GameTime = 0.f;        // seconds since the world began; zero when there is no world yet
	FGuid SessionId;             // minted by the server, adopted by clients on join; invalid before a session
	FString PlayerId;            // hashed server-minted id; empty on the server
	bool bIsServer = false;      // authoritative events versus observed ones
	int32 PartySize = 0;
	FString Build;               // FApp::GetBuildVersion() plus the git hash
	FString Map;
	bool bCheatsUsed = false;    // sticky true after the first cheat this session
};

// A small fluent builder for payloads, so a call site reads as one expression:
//   Telemetry->Emit(TelemetryEvents::CheatUsed, FTelemetryPayload().Set(TEXT("command"), Command));
class SALTYCORE_API FTelemetryPayload
{
public:
	FTelemetryPayload() : Object(MakeShared<FJsonObject>()) {}

	FTelemetryPayload& Set(const FString& Key, const FString& Value) { Object->SetStringField(Key, Value); return *this; }
	FTelemetryPayload& Set(const FString& Key, const TCHAR* Value)   { Object->SetStringField(Key, Value); return *this; }
	FTelemetryPayload& Set(const FString& Key, FName Value)          { Object->SetStringField(Key, Value.ToString()); return *this; }
	FTelemetryPayload& Set(const FString& Key, const FGuid& Value)   { Object->SetStringField(Key, Value.ToString(EGuidFormats::DigitsWithHyphensLower)); return *this; }
	FTelemetryPayload& Set(const FString& Key, double Value)         { Object->SetNumberField(Key, Value); return *this; }
	FTelemetryPayload& Set(const FString& Key, float Value)          { Object->SetNumberField(Key, Value); return *this; }
	FTelemetryPayload& Set(const FString& Key, int32 Value)          { Object->SetNumberField(Key, Value); return *this; }
	FTelemetryPayload& Set(const FString& Key, int64 Value)          { Object->SetNumberField(Key, static_cast<double>(Value)); return *this; }
	FTelemetryPayload& Set(const FString& Key, bool Value)           { Object->SetBoolField(Key, Value); return *this; }

	TSharedPtr<FJsonObject> Build() const { return Object; }
	operator TSharedPtr<FJsonObject>() const { return Object; }

private:
	TSharedPtr<FJsonObject> Object;
};

namespace Telemetry
{
	// The one serialisation of an event: the envelope's fields as snake_case keys, then "name" and "payload"
	// (an empty object when the event has none), condensed to a single line with no trailing newline. Pure, so
	// the sinks share it and the tests can check it without a sink.
	SALTYCORE_API FString ToJsonLine(const FTelemetryEnvelope& Envelope, const FTelemetryEvent& Event);
}