package verificationimp

import (
	"context"
	"errors"
	"time"

	"github.com/tech/sendico/pkg/db/repository"
	"github.com/tech/sendico/pkg/db/repository/builder"
	"github.com/tech/sendico/pkg/db/verification"
	"github.com/tech/sendico/pkg/merrors"
	"github.com/tech/sendico/pkg/model"
	mutil "github.com/tech/sendico/pkg/mutil/db"
	"github.com/tech/sendico/pkg/mutil/mzap"
	"go.mongodb.org/mongo-driver/v2/bson"
	"go.uber.org/zap"
)

func (db *verificationDB) Consume(
	ct context.Context,
	accountRef bson.ObjectID,
	purpose model.VerificationPurpose,
	rawToken string,
) (*model.VerificationToken, error) {

	now := time.Now().UTC()

	t, e := db.tf.CreateTransaction().Execute(
		ct,
		func(ctx context.Context) (any, error) {

			// 1) Load active tokens for this context
			activeFilter := repository.Query().And(
				repository.Filter("accountRef", accountRef),
				repository.Filter("purpose", purpose),
				repository.Filter("usedAt", nil),
				repository.Query().Comparison(repository.Field("expiresAt"), builder.Gt, now),
			)

			tokens, err := mutil.GetObjects[model.VerificationToken](
				ctx, db.Logger, activeFilter, nil, db.DBImp.Repository,
			)
			if err != nil {
				if errors.Is(err, merrors.ErrNoData) {
					db.Logger.Debug("No tokens found", zap.Error(err), mzap.AccRef(accountRef), zap.String("purpose", string(purpose)))
					return nil, verification.ErorrTokenNotFound()
				}
				db.Logger.Warn("Failed to load active tokens", zap.Error(err), mzap.AccRef(accountRef), zap.String("purpose", string(purpose)))
				return nil, err
			}

			if len(tokens) == 0 {
				db.Logger.Debug("No tokens found", zap.Error(err), mzap.AccRef(accountRef), zap.String("purpose", string(purpose)))
				return nil, verification.ErorrTokenNotFound()
			}

			// 2) Find matching token via hasher (OTP or Magic — doesn't matter)
			var token *model.VerificationToken

			for i := range tokens {
				t := &tokens[i]
				hash := hasherFor(t).Hash(rawToken, t)

				if hash == t.VerifyTokenHash {
					token = t
					break
				}
			}

			if token == nil {
				// wrong code/token → increment attempts
				for _, t := range tokens {
					_, _ = db.DBImp.PatchMany(
						ctx,
						repository.IDFilter(t.ID),
						repository.Patch().Inc(repository.Field("attempts"), 1),
					)
				}
				return nil, verification.ErorrTokenNotFound()
			}

			// 3) Static checks
			if token.UsedAt != nil {
				return nil, verification.ErorrTokenAlreadyUsed()
			}
			if !token.ExpiresAt.After(now) {
				return nil, verification.ErorrTokenExpired()
			}
			if token.MaxRetries != nil && token.Attempts >= *token.MaxRetries {
				return nil, verification.ErrorTokenAttemptsExceeded()
			}

			// 4) Atomic consume
			consumeFilter := repository.Query().And(
				repository.IDFilter(token.ID),
				repository.Filter("accountRef", accountRef),
				repository.Filter("purpose", purpose),
				repository.Filter("usedAt", nil),
				repository.Query().Comparison(repository.Field("expiresAt"), builder.Gt, now),
			)

			if token.MaxRetries != nil {
				consumeFilter = consumeFilter.And(
					repository.Query().Comparison(repository.Field("attempts"), builder.Lt, *token.MaxRetries),
				)
			}

			updated, err := db.DBImp.PatchMany(
				ctx,
				consumeFilter,
				repository.Patch().Set(repository.Field("usedAt"), now),
			)
			if err != nil {
				return nil, err
			}

			if updated == 1 {
				token.UsedAt = &now
				return token, nil
			}

			// 5) Consume failed → increment attempts
			_, _ = db.DBImp.PatchMany(
				ctx,
				repository.IDFilter(token.ID),
				repository.Patch().Inc(repository.Field("attempts"), 1),
			)

			// 6) Re-check state
			var fresh model.VerificationToken
			if err := db.DBImp.FindOne(ctx, repository.IDFilter(token.ID), &fresh); err != nil {
				return nil, merrors.Internal("failed to re-check token state")
			}

			if fresh.UsedAt != nil {
				return nil, verification.ErorrTokenAlreadyUsed()
			}
			if !fresh.ExpiresAt.After(now) {
				return nil, verification.ErorrTokenExpired()
			}
			if fresh.MaxRetries != nil && fresh.Attempts >= *fresh.MaxRetries {
				return nil, verification.ErrorTokenAttemptsExceeded()
			}

			return nil, verification.ErorrTokenNotFound()
		},
	)

	if e != nil {
		return nil, e
	}

	res, ok := t.(*model.VerificationToken)
	if !ok {
		return nil, merrors.Internal("unexpected token type")
	}
	return res, nil
}