package natspub

import (
	"context"
	"encoding/json"
	"fmt"
	"log/slog"
	"time"

	"github.com/nats-io/nats.go/jetstream"
)

type FraudScoredHandler func(ctx context.Context, evt FraudScored) error

type FraudScoredSubscriber struct {
	logger   *slog.Logger
	consumer jetstream.Consumer
	handler  FraudScoredHandler
}

func NewFraudScoredSubscriber(
	ctx context.Context,
	c *Client,
	durable string,
	handler FraudScoredHandler,
	logger *slog.Logger,
) (*FraudScoredSubscriber, error) {
	cons, err := c.js.CreateOrUpdateConsumer(ctx, StreamName, jetstream.ConsumerConfig{
		Durable:       durable,
		Name:          durable,
		FilterSubject: SubjectFraudScored,
		AckPolicy:     jetstream.AckExplicitPolicy,
		DeliverPolicy: jetstream.DeliverAllPolicy,
		MaxDeliver:    5,
		AckWait:       30 * time.Second,
	})
	if err != nil {
		return nil, fmt.Errorf("create consumer %s: %w", durable, err)
	}

	return &FraudScoredSubscriber{
		logger:   logger,
		consumer: cons,
		handler:  handler,
	}, nil
}

func (s *FraudScoredSubscriber) Start(ctx context.Context) (jetstream.ConsumeContext, error) {
	cc, err := s.consumer.Consume(func(msg jetstream.Msg) {
		var evt FraudScored
		if err := json.Unmarshal(msg.Data(), &evt); err != nil {
			s.logger.Error("decode fraud.scored", "err", err)
			_ = msg.Term()
			return
		}

		hctx, cancel := context.WithTimeout(ctx, 10*time.Second)
		defer cancel()

		if err := s.handler(hctx, evt); err != nil {
			s.logger.Error("handle fraud.scored",
				"err", err, "guest_id", evt.GuestID, "score", evt.Score)
			_ = msg.NakWithDelay(2 * time.Second)
			return
		}
		_ = msg.Ack()
	})
	if err != nil {
		return nil, fmt.Errorf("consume: %w", err)
	}
	return cc, nil
}