package redisstate

import (
	"context"
	"errors"
	"fmt"

	"galaxy/notification/internal/api/intentstream"
	"galaxy/notification/internal/service/acceptintent"

	"github.com/redis/go-redis/v9"
)

// AcceptanceStore provides the Redis-backed durable storage used by the
// intent-acceptance use case.
type AcceptanceStore struct {
	client *redis.Client
	writer *AtomicWriter
	keys   Keyspace
	cfg    AcceptanceConfig
}

// NewAcceptanceStore constructs one Redis-backed acceptance store.
func NewAcceptanceStore(client *redis.Client, cfg AcceptanceConfig) (*AcceptanceStore, error) {
	if client == nil {
		return nil, errors.New("new notification acceptance store: nil redis client")
	}

	writer, err := NewAtomicWriter(client, cfg)
	if err != nil {
		return nil, fmt.Errorf("new notification acceptance store: %w", err)
	}

	return &AcceptanceStore{
		client: client,
		writer: writer,
		keys:   Keyspace{},
		cfg:    cfg,
	}, nil
}

// CreateAcceptance stores one complete accepted notification write set in
// Redis.
func (store *AcceptanceStore) CreateAcceptance(ctx context.Context, input acceptintent.CreateAcceptanceInput) error {
	if store == nil || store.client == nil || store.writer == nil {
		return errors.New("create notification acceptance: nil store")
	}
	if ctx == nil {
		return errors.New("create notification acceptance: nil context")
	}
	if err := input.Validate(); err != nil {
		return fmt.Errorf("create notification acceptance: %w", err)
	}

	err := store.writer.CreateAcceptance(ctx, input)
	if errors.Is(err, ErrConflict) {
		return fmt.Errorf("create notification acceptance: %w", acceptintent.ErrConflict)
	}
	if err != nil {
		return fmt.Errorf("create notification acceptance: %w", err)
	}

	return nil
}

// GetIdempotency loads one accepted idempotency scope from Redis.
func (store *AcceptanceStore) GetIdempotency(ctx context.Context, producer intentstream.Producer, idempotencyKey string) (acceptintent.IdempotencyRecord, bool, error) {
	if store == nil || store.client == nil {
		return acceptintent.IdempotencyRecord{}, false, errors.New("get notification idempotency: nil store")
	}
	if ctx == nil {
		return acceptintent.IdempotencyRecord{}, false, errors.New("get notification idempotency: nil context")
	}

	payload, err := store.client.Get(ctx, store.keys.Idempotency(producer, idempotencyKey)).Bytes()
	switch {
	case errors.Is(err, redis.Nil):
		return acceptintent.IdempotencyRecord{}, false, nil
	case err != nil:
		return acceptintent.IdempotencyRecord{}, false, fmt.Errorf("get notification idempotency: %w", err)
	}

	record, err := UnmarshalIdempotency(payload)
	if err != nil {
		return acceptintent.IdempotencyRecord{}, false, fmt.Errorf("get notification idempotency: %w", err)
	}

	return record, true, nil
}

// GetNotification loads one accepted notification record from Redis.
func (store *AcceptanceStore) GetNotification(ctx context.Context, notificationID string) (acceptintent.NotificationRecord, bool, error) {
	if store == nil || store.client == nil {
		return acceptintent.NotificationRecord{}, false, errors.New("get notification record: nil store")
	}
	if ctx == nil {
		return acceptintent.NotificationRecord{}, false, errors.New("get notification record: nil context")
	}

	payload, err := store.client.Get(ctx, store.keys.Notification(notificationID)).Bytes()
	switch {
	case errors.Is(err, redis.Nil):
		return acceptintent.NotificationRecord{}, false, nil
	case err != nil:
		return acceptintent.NotificationRecord{}, false, fmt.Errorf("get notification record: %w", err)
	}

	record, err := UnmarshalNotification(payload)
	if err != nil {
		return acceptintent.NotificationRecord{}, false, fmt.Errorf("get notification record: %w", err)
	}

	return record, true, nil
}

// GetRoute loads one accepted notification route by NotificationID and
// RouteID.
func (store *AcceptanceStore) GetRoute(ctx context.Context, notificationID string, routeID string) (acceptintent.NotificationRoute, bool, error) {
	if store == nil || store.client == nil {
		return acceptintent.NotificationRoute{}, false, errors.New("get notification route: nil store")
	}
	if ctx == nil {
		return acceptintent.NotificationRoute{}, false, errors.New("get notification route: nil context")
	}

	payload, err := store.client.Get(ctx, store.keys.Route(notificationID, routeID)).Bytes()
	switch {
	case errors.Is(err, redis.Nil):
		return acceptintent.NotificationRoute{}, false, nil
	case err != nil:
		return acceptintent.NotificationRoute{}, false, fmt.Errorf("get notification route: %w", err)
	}

	record, err := UnmarshalRoute(payload)
	if err != nil {
		return acceptintent.NotificationRoute{}, false, fmt.Errorf("get notification route: %w", err)
	}

	return record, true, nil
}