package store

import (
	"context"
	"errors"
	"strings"

	"github.com/tech/sendico/gateway/tgsettle/storage"
	"github.com/tech/sendico/gateway/tgsettle/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/v2/mongo"
	"go.uber.org/zap"
)

const (
	paymentsCollection  = "payments"
	fieldIdempotencyKey = "idempotencyKey"
	fieldOperationRef   = "operationRef"
)

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

func NewPayments(logger mlogger.Logger, db *mongo.Database) (*Payments, error) {
	if db == nil {
		return nil, merrors.InvalidArgument("mongo database is nil")
	}
	if logger == nil {
		logger = zap.NewNop()
	}
	logger = logger.Named("payments").With(zap.String("collection", paymentsCollection))

	repo := repository.CreateMongoRepository(db, paymentsCollection)
	if err := repo.CreateIndex(&ri.Definition{
		Keys:   []ri.Key{{Field: fieldIdempotencyKey, Sort: ri.Asc}},
		Unique: true,
	}); err != nil {
		logger.Error("Failed to create payments idempotency index", zap.Error(err), zap.String("index_field", fieldIdempotencyKey))
		return nil, err
	}
	if err := repo.CreateIndex(&ri.Definition{
		Keys:   []ri.Key{{Field: fieldOperationRef, Sort: ri.Asc}},
		Unique: true,
		Sparse: true,
	}); err != nil {
		logger.Error("Failed to create payments operation index", zap.Error(err), zap.String("index_field", fieldOperationRef))
		return nil, err
	}

	p := &Payments{
		logger: logger,
		repo:   repo,
	}
	p.logger.Debug("Payments store initialised")
	return p, nil
}

func (p *Payments) FindByIdempotencyKey(ctx context.Context, key string) (*model.PaymentRecord, error) {
	key = strings.TrimSpace(key)
	if key == "" {
		return nil, merrors.InvalidArgument("idempotency key is required", "idempotency_key")
	}
	var result model.PaymentRecord
	err := p.repo.FindOneByFilter(ctx, repository.Filter(fieldIdempotencyKey, key), &result)
	if errors.Is(err, merrors.ErrNoData) {
		//nolint:nilnil // Not-found is represented as (nil, nil) by this store contract.
		return nil, nil
	}
	if err != nil {
		if !errors.Is(err, context.Canceled) && !errors.Is(err, context.DeadlineExceeded) {
			p.logger.Warn("Payment record lookup failed", zap.String("idempotency_key", key), zap.Error(err))
		}
		return nil, err
	}
	return &result, nil
}

func (p *Payments) FindByOperationRef(ctx context.Context, key string) (*model.PaymentRecord, error) {
	key = strings.TrimSpace(key)
	if key == "" {
		return nil, merrors.InvalidArgument("operation reference is required", "operation_ref")
	}
	var result model.PaymentRecord
	err := p.repo.FindOneByFilter(ctx, repository.Filter(fieldOperationRef, key), &result)
	if errors.Is(err, merrors.ErrNoData) {
		//nolint:nilnil // Not-found is represented as (nil, nil) by this store contract.
		return nil, nil
	}
	if err != nil {
		if !errors.Is(err, context.Canceled) && !errors.Is(err, context.DeadlineExceeded) {
			p.logger.Warn("Payment record lookup by operation ref failed", zap.String("operation_ref", key), zap.Error(err))
		}
		return nil, err
	}
	return &result, nil
}

func (p *Payments) Upsert(ctx context.Context, record *model.PaymentRecord) error {
	if record == nil {
		return merrors.InvalidArgument("payment record is nil", "record")
	}
	record.IdempotencyKey = strings.TrimSpace(record.IdempotencyKey)
	record.QuoteRef = strings.TrimSpace(record.QuoteRef)
	record.OutgoingLeg = strings.TrimSpace(record.OutgoingLeg)
	record.TargetChatID = strings.TrimSpace(record.TargetChatID)
	record.IntentRef = strings.TrimSpace(record.IntentRef)
	record.OperationRef = strings.TrimSpace(record.OperationRef)
	if record.IntentRef == "" {
		return merrors.InvalidArgument("intention reference is required", "intent_ref")
	}
	if record.IdempotencyKey == "" {
		return merrors.InvalidArgument("idempotency key is required", "idempotency_key")
	}
	if record.IntentRef == "" {
		return merrors.InvalidArgument("intention reference key is required", "intent_ref")
	}

	existing, err := p.FindByIdempotencyKey(ctx, record.IdempotencyKey)
	if err != nil {
		return err
	}
	if existing != nil {
		record.ID = existing.ID
		if record.CreatedAt.IsZero() {
			record.CreatedAt = existing.CreatedAt
		}
	}

	err = p.repo.Upsert(ctx, record)
	if mongo.IsDuplicateKeyError(err) {
		// Concurrent insert by idempotency key: resolve existing ID and retry replace-by-ID.
		existing, lookupErr := p.FindByIdempotencyKey(ctx, record.IdempotencyKey)
		if lookupErr != nil {
			err = lookupErr
		} else if existing != nil {
			record.ID = existing.ID
			if record.CreatedAt.IsZero() {
				record.CreatedAt = existing.CreatedAt
			}
			err = p.repo.Upsert(ctx, record)
		}
	}
	if err != nil {
		if !errors.Is(err, context.Canceled) && !errors.Is(err, context.DeadlineExceeded) {
			p.logger.Warn("Failed to upsert payment record",
				zap.String("idempotency_key", record.IdempotencyKey),
				zap.String("intent_ref", record.IntentRef),
				zap.String("quote_ref", record.QuoteRef),
				zap.Error(err))
		}
		return err
	}
	return nil
}

var _ storage.PaymentsStore = (*Payments)(nil)