package service

import (
	"context"
	"fmt"
	"sync"

	"github.com/ethereum/go-ethereum/common"
	"github.com/synapsecns/sanguine/core/metrics"
	"github.com/synapsecns/sanguine/services/rfq/guard/guarddb"
	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/metric"
)

const meterName = "github.com/synapsecns/sanguine/services/rfq/guard/service"

// generate an interface for otelRecorder that exports the public method.
// this allows us to avoid using recordX externally anad makes the package less confusing.
//
// =============================================================================
// =============================================================================
// IMPORTANT: DO NOT REMOVE THIS COMMENT.
// NOTICE: PLEASE MAKE SURE YOU UPDATE BOTH THE DOCS AND THE GRAFANA DASHBOARD (IF NEEDED) AFTER UPDATING METRICS.
// =============================================================================
// =============================================================================
//
//go:generate go run github.com/vburenin/ifacemaker -f otel.go -s otelRecorder -i iOtelRecorder -p service -o otel_generated.go -c "autogenerated file"
type otelRecorder struct {
	metrics metrics.Handler
	// meter is the metrics meter.
	meter metric.Meter
	// disputeGauge is the gauge for the disputeCounts.
	disputeGauge metric.Int64ObservableGauge
	// db is a database connection for fetching disputes.
	db guarddb.Service
	// walletAddress is the wallet address for the signer.
	walletAddress common.Address
	// mux is a mutex used for making sure only one db query is run at a time.
	mux sync.Mutex
}

func newOtelRecorder(meterHandler metrics.Handler, walletAddress common.Address, db guarddb.Service) (_ iOtelRecorder, err error) {
	or := otelRecorder{
		metrics:       meterHandler,
		meter:         meterHandler.Meter(meterName),
		db:            db,
		walletAddress: walletAddress,
	}

	or.disputeGauge, err = or.meter.Int64ObservableGauge("dispute_count")
	if err != nil {
		return nil, fmt.Errorf("could not create dispute count gauge: %w", err)
	}

	_, err = or.meter.RegisterCallback(or.recordDisputeCounts, or.disputeGauge)
	if err != nil {
		return nil, fmt.Errorf("could not register callback for dispute count gauge: %w", err)
	}

	return &or, nil
}

func (o *otelRecorder) recordDisputeCounts(ctx context.Context, observer metric.Observer) (err error) {
	if o.metrics == nil || o.disputeGauge == nil || o.db == nil {
		return nil
	}

	// make sure we aren't making simultaneous db queries
	if o.mux.TryLock() {
		defer o.mux.Unlock()
	} else {
		return nil
	}

	results, err := o.db.GetPendingProvensByStatus(ctx, guarddb.DisputePending, guarddb.Disputed)
	if err != nil {
		return fmt.Errorf("could not get disputes: %w", err)
	}
	opts := metric.WithAttributes(
		attribute.String("wallet", o.walletAddress.Hex()),
	)
	observer.ObserveInt64(o.disputeGauge, int64(len(results)), opts)

	return nil
}