package store

import (
	"context"
	"errors"
	"strings"
	"time"

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

const (
	defaultWalletPageSize int64 = 50
	maxWalletPageSize     int64 = 200
)

type Wallets struct {
	logger      mlogger.Logger
	walletRepo  repository.Repository
	balanceRepo repository.Repository
}

// NewWallets constructs a Mongo-backed wallets store.
func NewWallets(logger mlogger.Logger, db *mongo.Database) (*Wallets, error) {
	if db == nil {
		return nil, merrors.InvalidArgument("mongo database is nil")
	}

	walletRepo := repository.CreateMongoRepository(db, mservice.ChainWallets)
	walletIndexes := []*ri.Definition{
		{
			Keys:   []ri.Key{{Field: "walletRef", Sort: ri.Asc}},
			Unique: true,
		},
		{
			Keys:   []ri.Key{{Field: "idempotencyKey", Sort: ri.Asc}},
			Unique: true,
		},
		{
			Keys:   []ri.Key{{Field: "depositAddress", Sort: ri.Asc}},
			Unique: true,
		},
		{
			Keys: []ri.Key{{Field: "organizationRef", Sort: ri.Asc}, {Field: "ownerRef", Sort: ri.Asc}},
		},
	}
	for _, def := range walletIndexes {
		if err := walletRepo.CreateIndex(def); err != nil {
			logger.Error("failed to ensure wallet index", zap.String("collection", walletRepo.Collection()), zap.Error(err))
			return nil, err
		}
	}

	balanceRepo := repository.CreateMongoRepository(db, mservice.ChainWalletBalances)
	balanceIndexes := []*ri.Definition{
		{
			Keys:   []ri.Key{{Field: "walletRef", Sort: ri.Asc}},
			Unique: true,
		},
	}
	for _, def := range balanceIndexes {
		if err := balanceRepo.CreateIndex(def); err != nil {
			logger.Error("failed to ensure wallet balance index", zap.String("collection", balanceRepo.Collection()), zap.Error(err))
			return nil, err
		}
	}

	childLogger := logger.Named("wallets")
	childLogger.Debug("wallet stores initialised")

	return &Wallets{
		logger:      childLogger,
		walletRepo:  walletRepo,
		balanceRepo: balanceRepo,
	}, nil
}

func (w *Wallets) Create(ctx context.Context, wallet *model.ManagedWallet) (*model.ManagedWallet, error) {
	if wallet == nil {
		return nil, merrors.InvalidArgument("walletsStore: nil wallet")
	}
	wallet.Normalize()
	if strings.TrimSpace(wallet.WalletRef) == "" {
		return nil, merrors.InvalidArgument("walletsStore: empty walletRef")
	}
	if wallet.Status == "" {
		wallet.Status = model.ManagedWalletStatusActive
	}
	if strings.TrimSpace(wallet.IdempotencyKey) == "" {
		return nil, merrors.InvalidArgument("walletsStore: empty idempotencyKey")
	}
	if err := w.walletRepo.Insert(ctx, wallet, repository.Filter("idempotencyKey", wallet.IdempotencyKey)); err != nil {
		if errors.Is(err, merrors.ErrDataConflict) {
			w.logger.Debug("wallet already exists", zap.String("wallet_ref", wallet.WalletRef), zap.String("idempotency_key", wallet.IdempotencyKey))
			return wallet, nil
		}
		return nil, err
	}
	w.logger.Debug("wallet created", zap.String("wallet_ref", wallet.WalletRef))
	return wallet, nil
}

func (w *Wallets) Get(ctx context.Context, walletRef string) (*model.ManagedWallet, error) {
	walletRef = strings.TrimSpace(walletRef)
	if walletRef == "" {
		return nil, merrors.InvalidArgument("walletsStore: empty walletRef")
	}
	wallet := &model.ManagedWallet{}
	if err := w.walletRepo.FindOneByFilter(ctx, repository.Filter("walletRef", walletRef), wallet); err != nil {
		return nil, err
	}
	return wallet, nil
}

func (w *Wallets) List(ctx context.Context, filter model.ManagedWalletFilter) (*model.ManagedWalletList, error) {
	query := repository.Query()

	if org := strings.TrimSpace(filter.OrganizationRef); org != "" {
		query = query.Filter(repository.Field("organizationRef"), org)
	}
	if owner := strings.TrimSpace(filter.OwnerRef); owner != "" {
		query = query.Filter(repository.Field("ownerRef"), owner)
	}
	if network := strings.TrimSpace(filter.Network); network != "" {
		query = query.Filter(repository.Field("network"), strings.ToLower(network))
	}
	if token := strings.TrimSpace(filter.TokenSymbol); token != "" {
		query = query.Filter(repository.Field("tokenSymbol"), strings.ToUpper(token))
	}

	if cursor := strings.TrimSpace(filter.Cursor); cursor != "" {
		if oid, err := primitive.ObjectIDFromHex(cursor); err == nil {
			query = query.Comparison(repository.IDField(), builder.Gt, oid)
		} else {
			w.logger.Warn("ignoring invalid wallet cursor", zap.String("cursor", cursor), zap.Error(err))
		}
	}

	limit := sanitizeWalletLimit(filter.Limit)
	fetchLimit := limit + 1
	query = query.Sort(repository.IDField(), true).Limit(&fetchLimit)

	wallets := make([]*model.ManagedWallet, 0, fetchLimit)
	decoder := func(cur *mongo.Cursor) error {
		item := &model.ManagedWallet{}
		if err := cur.Decode(item); err != nil {
			return err
		}
		wallets = append(wallets, item)
		return nil
	}

	if err := w.walletRepo.FindManyByFilter(ctx, query, decoder); err != nil && !errors.Is(err, merrors.ErrNoData) {
		return nil, err
	}

	nextCursor := ""
	if int64(len(wallets)) == fetchLimit {
		last := wallets[len(wallets)-1]
		nextCursor = last.ID.Hex()
		wallets = wallets[:len(wallets)-1]
	}

	return &model.ManagedWalletList{
		Items:      wallets,
		NextCursor: nextCursor,
	}, nil
}

func (w *Wallets) SaveBalance(ctx context.Context, balance *model.WalletBalance) error {
	if balance == nil {
		return merrors.InvalidArgument("walletsStore: nil balance")
	}
	balance.Normalize()
	if strings.TrimSpace(balance.WalletRef) == "" {
		return merrors.InvalidArgument("walletsStore: empty walletRef for balance")
	}
	if balance.CalculatedAt.IsZero() {
		balance.CalculatedAt = time.Now().UTC()
	}

	existing := &model.WalletBalance{}
	err := w.balanceRepo.FindOneByFilter(ctx, repository.Filter("walletRef", balance.WalletRef), existing)
	switch {
	case err == nil:
		existing.Available = balance.Available
		existing.PendingInbound = balance.PendingInbound
		existing.PendingOutbound = balance.PendingOutbound
		existing.CalculatedAt = balance.CalculatedAt
		if err := w.balanceRepo.Update(ctx, existing); err != nil {
			return err
		}
		return nil
	case errors.Is(err, merrors.ErrNoData):
		if err := w.balanceRepo.Insert(ctx, balance, repository.Filter("walletRef", balance.WalletRef)); err != nil {
			return err
		}
		return nil
	default:
		return err
	}
}

func (w *Wallets) GetBalance(ctx context.Context, walletRef string) (*model.WalletBalance, error) {
	walletRef = strings.TrimSpace(walletRef)
	if walletRef == "" {
		return nil, merrors.InvalidArgument("walletsStore: empty walletRef")
	}
	balance := &model.WalletBalance{}
	if err := w.balanceRepo.FindOneByFilter(ctx, repository.Filter("walletRef", walletRef), balance); err != nil {
		return nil, err
	}
	return balance, nil
}

func sanitizeWalletLimit(requested int32) int64 {
	if requested <= 0 {
		return defaultWalletPageSize
	}
	if requested > int32(maxWalletPageSize) {
		return maxWalletPageSize
	}
	return int64(requested)
}

var _ storage.WalletsStore = (*Wallets)(nil)