package store

import (
	"context"
	"errors"
	"time"

	"github.com/tech/sendico/fx/storage"
	"github.com/tech/sendico/fx/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/mongo"
	"go.uber.org/zap"
)

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

func NewRates(logger mlogger.Logger, db *mongo.Database) (storage.RatesStore, error) {
	repo := repository.CreateMongoRepository(db, model.RatesCollection)

	indexes := []*ri.Definition{
		{
			Keys: []ri.Key{
				{Field: "pair.base", Sort: ri.Asc},
				{Field: "pair.quote", Sort: ri.Asc},
				{Field: "provider", Sort: ri.Asc},
				{Field: "asOfUnixMs", Sort: ri.Desc},
			},
		},
		{
			Keys: []ri.Key{
				{Field: "rateRef", Sort: ri.Asc},
			},
			Unique: true,
		},
	}

	ttlSeconds := int32(24 * 60 * 60)
	indexes = append(indexes, &ri.Definition{
		Keys: []ri.Key{
			{Field: "asOf", Sort: ri.Asc},
		},
		TTL:  &ttlSeconds,
		Name: "rates_as_of_ttl",
	})

	for _, def := range indexes {
		if err := repo.CreateIndex(def); err != nil {
			logger.Error("Failed to ensure rates index", zap.Error(err))
			return nil, err
		}
	}
	logger.Debug("Rates store initialised", zap.String("collection", model.RatesCollection))
	return &ratesStore{
		logger: logger.Named(model.RatesCollection),
		repo:   repo,
	}, nil
}

func (r *ratesStore) UpsertSnapshot(ctx context.Context, snapshot *model.RateSnapshot) error {
	if snapshot == nil {
		r.logger.Warn("Attempt to upsert nil snapshot")
		return merrors.InvalidArgument("ratesStore: nil snapshot")
	}
	if snapshot.RateRef == "" {
		r.logger.Warn("Attempt to upsert snapshot with empty rate_ref")
		return merrors.InvalidArgument("ratesStore: empty rateRef")
	}

	if snapshot.AsOfUnixMs > 0 && snapshot.AsOf == nil {
		asOf := time.UnixMilli(snapshot.AsOfUnixMs).UTC()
		snapshot.AsOf = &asOf
	}

	existing := &model.RateSnapshot{}
	filter := repository.Filter("rateRef", snapshot.RateRef)
	err := r.repo.FindOneByFilter(ctx, filter, existing)
	if err != nil {
		if errors.Is(err, merrors.ErrNoData) {
			r.logger.Debug("Inserting new rate snapshot", zap.String("rate_ref", snapshot.RateRef))
			return r.repo.Insert(ctx, snapshot, filter)
		}
		r.logger.Warn("Failed to query rate snapshot", zap.Error(err), zap.String("rate_ref", snapshot.RateRef))
		return err
	}

	if existing.GetID() != nil {
		snapshot.SetID(*existing.GetID())
	}
	r.logger.Debug("Updating rate snapshot", zap.String("rate_ref", snapshot.RateRef))
	return r.repo.Update(ctx, snapshot)
}

func (r *ratesStore) LatestSnapshot(ctx context.Context, pair model.CurrencyPair, provider string) (*model.RateSnapshot, error) {
	query := repository.Query().
		Filter(repository.Field("pair").Dot("base"), pair.Base).
		Filter(repository.Field("pair").Dot("quote"), pair.Quote)

	if provider != "" {
		query = query.Filter(repository.Field("provider"), provider)
	}

	limit := int64(1)
	query = query.Sort(repository.Field("asOfUnixMs"), false).Limit(&limit)

	var result *model.RateSnapshot
	err := r.repo.FindManyByFilter(ctx, query, func(cur *mongo.Cursor) error {
		doc := &model.RateSnapshot{}
		if err := cur.Decode(doc); err != nil {
			return err
		}
		result = doc
		return nil
	})
	if err != nil {
		return nil, err
	}
	if result == nil {
		return nil, merrors.ErrNoData
	}
	return result, nil
}