package quotation

import (
	"context"
	"errors"
	"strings"

	"github.com/tech/sendico/payments/storage"
	"github.com/tech/sendico/payments/storage/model"
	"github.com/tech/sendico/pkg/merrors"
	quotationv1 "github.com/tech/sendico/pkg/proto/payments/quotation/v1"
	sharedv1 "github.com/tech/sendico/pkg/proto/payments/shared/v1"
	"go.mongodb.org/mongo-driver/v2/bson"
	"google.golang.org/protobuf/proto"
)

func validateMetaAndOrgRef(meta *sharedv1.RequestMeta) (string, bson.ObjectID, error) {
	if meta == nil {
		return "", bson.NilObjectID, merrors.InvalidArgument("meta is required")
	}
	orgRef := strings.TrimSpace(meta.GetOrganizationRef())
	if orgRef == "" {
		return "", bson.NilObjectID, merrors.InvalidArgument("organization_ref is required")
	}
	orgID, err := bson.ObjectIDFromHex(orgRef)
	if err != nil {
		return "", bson.NilObjectID, merrors.InvalidArgument("organization_ref must be a valid objectID")
	}
	return orgRef, orgID, nil
}

func requireNonNilIntent(intent *sharedv1.PaymentIntent) error {
	if intent == nil {
		return merrors.InvalidArgument("intent is required")
	}
	if intent.GetAmount() == nil {
		return merrors.InvalidArgument("intent.amount is required")
	}
	if strings.TrimSpace(intent.GetSettlementCurrency()) == "" {
		return merrors.InvalidArgument("intent.settlement_currency is required")
	}
	return nil
}

func ensureQuotesStore(repo storage.Repository) (storage.QuotesStore, error) {
	if repo == nil {
		return nil, errStorageUnavailable
	}
	store := repo.Quotes()
	if store == nil {
		return nil, errStorageUnavailable
	}
	return store, nil
}

type quoteResolutionInput struct {
	OrgRef         string
	OrgID          bson.ObjectID
	Meta           *sharedv1.RequestMeta
	Intent         *sharedv1.PaymentIntent
	QuoteRef       string
	IdempotencyKey string
}

type quoteResolutionError struct {
	code string
	err  error
}

func (e quoteResolutionError) Error() string { return e.err.Error() }

func (s *Service) resolvePaymentQuote(ctx context.Context, in quoteResolutionInput) (*sharedv1.PaymentQuote, *sharedv1.PaymentIntent, *model.PaymentPlan, error) {
	if ref := strings.TrimSpace(in.QuoteRef); ref != "" {
		quotesStore, err := ensureQuotesStore(s.storage)
		if err != nil {
			return nil, nil, nil, err
		}
		record, err := quotesStore.GetByRef(ctx, in.OrgID, ref)
		if err != nil {
			if errors.Is(err, storage.ErrQuoteNotFound) {
				return nil, nil, nil, quoteResolutionError{code: "quote_not_found", err: merrors.InvalidArgument("quote_ref not found or expired")}
			}
			return nil, nil, nil, err
		}
		if !record.ExpiresAt.IsZero() && s.clock.Now().After(record.ExpiresAt) {
			return nil, nil, nil, quoteResolutionError{code: "quote_expired", err: merrors.InvalidArgument("quote_ref expired")}
		}
		intent, err := recordIntentFromQuote(record)
		if err != nil {
			return nil, nil, nil, err
		}
		if in.Intent != nil && !proto.Equal(intent, in.Intent) {
			return nil, nil, nil, quoteResolutionError{code: "quote_intent_mismatch", err: merrors.InvalidArgument("quote_ref does not match intent")}
		}
		quote, err := recordQuoteFromQuote(record)
		if err != nil {
			return nil, nil, nil, err
		}
		quote.QuoteRef = ref
		plan, err := recordPlanFromQuote(record)
		if err != nil {
			return nil, nil, nil, err
		}
		return quote, intent, plan, nil
	}

	if in.Intent == nil {
		return nil, nil, nil, merrors.InvalidArgument("intent is required")
	}
	req := &quotationv1.QuotePaymentRequest{
		Meta:           in.Meta,
		IdempotencyKey: in.IdempotencyKey,
		Intent:         in.Intent,
		PreviewOnly:    false,
	}
	quote, _, err := s.buildPaymentQuote(ctx, in.OrgRef, req)
	if err != nil {
		return nil, nil, nil, err
	}
	plan, err := s.buildPaymentPlan(ctx, in.OrgID, in.Intent, in.IdempotencyKey, quote)
	if err != nil {
		return nil, nil, nil, err
	}
	return quote, in.Intent, plan, nil
}

func recordIntentFromQuote(record *model.PaymentQuoteRecord) (*sharedv1.PaymentIntent, error) {
	if record == nil {
		return nil, merrors.InvalidArgument("stored quote payload is incomplete")
	}
	if len(record.Intents) > 0 {
		if len(record.Intents) != 1 {
			return nil, merrors.InvalidArgument("stored quote payload is incomplete")
		}
		return protoIntentFromModel(record.Intents[0]), nil
	}
	if record.Intent.Amount == nil && (record.Intent.Kind == "" || record.Intent.Kind == model.PaymentKindUnspecified) {
		return nil, merrors.InvalidArgument("stored quote payload is incomplete")
	}
	return protoIntentFromModel(record.Intent), nil
}

func recordQuoteFromQuote(record *model.PaymentQuoteRecord) (*sharedv1.PaymentQuote, error) {
	if record == nil {
		return nil, merrors.InvalidArgument("stored quote is empty")
	}
	if record.Quote != nil {
		return modelQuoteToProto(record.Quote), nil
	}
	if len(record.Quotes) > 0 {
		if len(record.Quotes) != 1 {
			return nil, merrors.InvalidArgument("stored quote payload is incomplete")
		}
		return modelQuoteToProto(record.Quotes[0]), nil
	}
	return nil, merrors.InvalidArgument("stored quote is empty")
}

func recordPlanFromQuote(record *model.PaymentQuoteRecord) (*model.PaymentPlan, error) {
	if record == nil {
		return nil, merrors.InvalidArgument("stored quote payload is incomplete")
	}
	if len(record.Plans) > 0 {
		if len(record.Plans) != 1 {
			return nil, merrors.InvalidArgument("stored quote payload is incomplete")
		}
		return cloneStoredPaymentPlan(record.Plans[0]), nil
	}
	if record.Plan != nil {
		return cloneStoredPaymentPlan(record.Plan), nil
	}
	return nil, nil
}

func newPayment(orgID bson.ObjectID, intent *sharedv1.PaymentIntent, idempotencyKey string, metadata map[string]string, quote *sharedv1.PaymentQuote) *model.Payment {
	entity := &model.Payment{}
	entity.SetID(bson.NewObjectID())
	entity.SetOrganizationRef(orgID)
	entity.PaymentRef = entity.GetID().Hex()
	entity.IdempotencyKey = idempotencyKey
	entity.State = model.PaymentStateAccepted
	entity.Intent = intentFromProto(intent)
	entity.Metadata = cloneMetadata(metadata)
	entity.LastQuote = quoteSnapshotToModel(quote)
	entity.Normalize()
	return entity
}