package store

import (
	"context"
	"time"

	"github.com/tech/sendico/ledger/storage"
	"github.com/tech/sendico/ledger/storage/model"
	"github.com/tech/sendico/pkg/db/repository"
	ri "github.com/tech/sendico/pkg/db/repository/index"
	"github.com/tech/sendico/pkg/merrors"
	"github.com/tech/sendico/pkg/mlogger"
	"go.mongodb.org/mongo-driver/bson/primitive"
	"go.mongodb.org/mongo-driver/mongo"
	"go.uber.org/zap"
)

type outboxStore struct {
	logger mlogger.Logger
	repo   repository.Repository
}

func NewOutbox(logger mlogger.Logger, db *mongo.Database) (storage.OutboxStore, error) {
	repo := repository.CreateMongoRepository(db, model.OutboxCollection)

	// Create index on status + createdAt for efficient pending query
	statusIndex := &ri.Definition{
		Keys: []ri.Key{
			{Field: "status", Sort: ri.Asc},
			{Field: "createdAt", Sort: ri.Asc},
		},
	}
	if err := repo.CreateIndex(statusIndex); err != nil {
		logger.Error("failed to ensure outbox status index", zap.Error(err))
		return nil, err
	}

	// Create unique index on eventId for deduplication
	eventIdIndex := &ri.Definition{
		Keys: []ri.Key{
			{Field: "eventId", Sort: ri.Asc},
		},
		Unique: true,
	}
	if err := repo.CreateIndex(eventIdIndex); err != nil {
		logger.Error("failed to ensure outbox eventId index", zap.Error(err))
		return nil, err
	}

	childLogger := logger.Named(model.OutboxCollection)
	childLogger.Debug("outbox store initialised", zap.String("collection", model.OutboxCollection))

	return &outboxStore{
		logger: childLogger,
		repo:   repo,
	}, nil
}

func (o *outboxStore) Create(ctx context.Context, event *model.OutboxEvent) error {
	if event == nil {
		o.logger.Warn("attempt to create nil outbox event")
		return merrors.InvalidArgument("outboxStore: nil outbox event")
	}

	if err := o.repo.Insert(ctx, event, nil); err != nil {
		if mongo.IsDuplicateKeyError(err) {
			o.logger.Warn("duplicate event ID", zap.String("eventId", event.EventID))
			return merrors.DataConflict("outbox event with this ID already exists")
		}
		o.logger.Warn("failed to create outbox event", zap.Error(err))
		return err
	}

	o.logger.Debug("outbox event created", zap.String("eventId", event.EventID),
		zap.String("subject", event.Subject))
	return nil
}

func (o *outboxStore) ListPending(ctx context.Context, limit int) ([]*model.OutboxEvent, error) {
	limit64 := int64(limit)
	query := repository.Query().
		Filter(repository.Field("status"), model.OutboxStatusPending).
		Limit(&limit64).
		Sort(repository.Field("createdAt"), true) // true = ascending (oldest first)

	events := make([]*model.OutboxEvent, 0)
	err := o.repo.FindManyByFilter(ctx, query, func(cur *mongo.Cursor) error {
		doc := &model.OutboxEvent{}
		if err := cur.Decode(doc); err != nil {
			return err
		}
		events = append(events, doc)
		return nil
	})
	if err != nil {
		o.logger.Warn("failed to list pending outbox events", zap.Error(err))
		return nil, err
	}

	o.logger.Debug("listed pending outbox events", zap.Int("count", len(events)))
	return events, nil
}

func (o *outboxStore) MarkSent(ctx context.Context, eventRef primitive.ObjectID, sentAt time.Time) error {
	if eventRef.IsZero() {
		o.logger.Warn("attempt to mark sent with zero event ID")
		return merrors.InvalidArgument("outboxStore: zero event ID")
	}

	patch := repository.Patch().
		Set(repository.Field("status"), model.OutboxStatusSent).
		Set(repository.Field("sentAt"), sentAt)

	if err := o.repo.Patch(ctx, eventRef, patch); err != nil {
		o.logger.Warn("failed to mark outbox event as sent", zap.Error(err), zap.String("eventRef", eventRef.Hex()))
		return err
	}

	o.logger.Debug("outbox event marked as sent", zap.String("eventRef", eventRef.Hex()))
	return nil
}

func (o *outboxStore) MarkFailed(ctx context.Context, eventRef primitive.ObjectID) error {
	if eventRef.IsZero() {
		o.logger.Warn("attempt to mark failed with zero event ID")
		return merrors.InvalidArgument("outboxStore: zero event ID")
	}

	patch := repository.Patch().Set(repository.Field("status"), model.OutboxStatusFailed)

	if err := o.repo.Patch(ctx, eventRef, patch); err != nil {
		o.logger.Warn("failed to mark outbox event as failed", zap.Error(err), zap.String("eventRef", eventRef.Hex()))
		return err
	}

	o.logger.Debug("outbox event marked as failed", zap.String("eventRef", eventRef.Hex()))
	return nil
}

func (o *outboxStore) IncrementAttempts(ctx context.Context, eventRef primitive.ObjectID) error {
	if eventRef.IsZero() {
		o.logger.Warn("attempt to increment attempts with zero event ID")
		return merrors.InvalidArgument("outboxStore: zero event ID")
	}

	patch := repository.Patch().Inc(repository.Field("attempts"), 1)

	if err := o.repo.Patch(ctx, eventRef, patch); err != nil {
		o.logger.Warn("failed to increment outbox attempts", zap.Error(err), zap.String("eventRef", eventRef.Hex()))
		return err
	}

	o.logger.Debug("outbox attempts incremented", zap.String("eventRef", eventRef.Hex()))
	return nil
}