package accountserviceimp

import (
	"context"
	"errors"
	"fmt"
	customermodel "git.sendico.io/tech/sxchnge/product/customers/model"
	verificationmodel "git.sendico.io/tech/sxchnge/product/verification/model"
	"time"
	"unicode"

	"git.sendico.io/tech/sxchnge/product/auth/config"
	authstorage "git.sendico.io/tech/sxchnge/product/auth/storage"
	"git.sendico.io/tech/sxchnge/product/customers/store"
	"git.sendico.io/tech/sxchnge/product/sessions/store"
	"git.sendico.io/tech/sxchnge/product/verification/store"
	"git.sendico.io/tech/sxchnge/shared/database"
	"git.sendico.io/tech/sxchnge/shared/database/transaction"
	"git.sendico.io/tech/sxchnge/shared/errors"
	"git.sendico.io/tech/sxchnge/shared/logging"
	"git.sendico.io/tech/sxchnge/shared/logging/fields"
	"go.mongodb.org/mongo-driver/v2/bson"
	"go.uber.org/zap"
)

type service struct {
	logger    mlogger.Logger
	accountDB account.DB
	config    *middleware.PasswordConfig

	vdb          verification.DB
	sessions     refreshtokens.DB
	transactions transaction.Factory
}

func validateUserRequest(u *customermodel.Account) error {
	if u == nil {
		return merrors.InvalidArgument("account is required")
	}
	if u.Name == "" {
		return merrors.InvalidArgument("Name must not be empty")
	}
	if u.Login == "" {
		return merrors.InvalidArgument("Login must not be empty")
	}
	if u.Password == "" {
		return merrors.InvalidArgument("Password must not be empty")
	}
	return nil
}

func (s *service) ValidatePassword(
	password string,
	oldPassword *string,
) error {
	var hasDigit, hasUpper, hasLower, hasSpecial bool

	if oldPassword != nil {
		if *oldPassword == password {
			return merrors.InvalidArgument("New password cannot be the same as the old password")
		}
	}

	if len(password) < s.config.Check.MinLength {
		return merrors.InvalidArgument(fmt.Sprintf("Password must be at least %d characters long", s.config.Check.MinLength))
	}

	// Check for digit, uppercase, lowercase, and special character
	for _, char := range password {
		switch {
		case unicode.IsDigit(char):
			hasDigit = true
		case unicode.IsUpper(char):
			hasUpper = true
		case unicode.IsLower(char):
			hasLower = true
		case unicode.IsPunct(char) || unicode.IsSymbol(char):
			hasSpecial = true
		}
	}

	if s.config.Check.Digit && !hasDigit {
		return merrors.InvalidArgument("Password must contain at least one digit")
	}
	if s.config.Check.Upper && !hasUpper {
		return merrors.InvalidArgument("Password must contain at least one uppercase letter")
	}
	if s.config.Check.Lower && !hasLower {
		return merrors.InvalidArgument("Password must contain at least one lowercase letter")
	}
	if s.config.Check.Special && !hasSpecial {
		return merrors.InvalidArgument("Password must contain at least one special character")
	}

	// If all checks pass, return nil (no error)
	return nil
}

func (s *service) ValidateAccount(acct *customermodel.Account) error {
	if err := validateUserRequest(acct); err != nil {
		s.logger.Warn("Invalid signup account received", zap.Error(err))
		return err
	}

	if err := s.ValidatePassword(acct.Password, nil); err != nil {
		s.logger.Warn("Password validation failed", zap.Error(err), mzap.Email(acct.Login))
		return err
	}

	if err := acct.HashPassword(); err != nil {
		s.logger.Warn("Failed to hash password", zap.Error(err), mzap.Email(acct.Login))
		return err
	}

	return nil
}

func (s *service) CreateAccount(
	ctx context.Context,
	acct *customermodel.Account,
) (string, error) {
	return s.createAccount(ctx, acct, "")
}

func (s *service) CreateAccountWithActivationKey(ctx context.Context, acct *customermodel.Account, key string) (string, error) {
	if len(key) < 32 || len(key) > 128 {
		return "", merrors.InvalidArgument("server activation key required")
	}
	return s.createAccount(ctx, acct, key)
}

func (s *service) createAccount(ctx context.Context, acct *customermodel.Account, key string) (string, error) {
	if acct == nil {
		return "", merrors.InvalidArgument("account is required")
	}
	if !acct.ID.IsZero() {
		return "", merrors.InvalidArgument("new account must not have an ID")
	}
	candidate := acct.Copy()
	if err := s.ValidateAccount(candidate); err != nil {
		return "", err
	}
	candidate.Status = customermodel.AccountPendingVerification
	// The customer and activation token either both commit or neither does.
	var saved *customermodel.Account
	result, err := s.transactions.CreateTransaction().Execute(ctx, func(tx context.Context) (any, error) {
		saved = candidate.Copy()
		if err := s.accountDB.Create(tx, saved); err != nil {
			return nil, err
		}
		return s.vdb.Create(tx, verification.NewLinkRequest(saved.ID, verificationmodel.PurposeAccountActivation, "").WithTTL(24*time.Hour).WithIdempotencyKey(key))
	})
	if err != nil {
		if errors.Is(err, merrors.ErrDataConflict) {
			s.logger.Info("Customer login already exists")
		} else {
			s.logger.Warn("Customer creation failed", zap.Error(err))
		}
		return "", err
	}
	token, ok := result.(string)
	if !ok {
		return "", merrors.Internal("unexpected account creation result")
	}
	*acct = *saved
	s.logger.Info("Customer created pending verification", mzap.AccRef(acct.ID))
	return token, nil
}

func (s *service) VerifyAccount(
	ctx context.Context,
	acct *customermodel.Account,
) (string, error) {
	if acct == nil || acct.ID.IsZero() {
		return "", merrors.InvalidArgument("customer reference is required")
	}
	token, err := s.vdb.Create(
		ctx,
		verification.NewLinkRequest(*acct.GetID(), verificationmodel.PurposeAccountActivation, "").
			WithTTL(time.Hour*24),
	)
	if err != nil {
		s.logger.Warn("Failed to create verification token for new account", zap.Error(err), mzap.StorableRef(acct))
		return "", err
	}

	return token, nil

}

func (s *service) DeleteAccount(
	ctx context.Context,
	accountRef bson.ObjectID,
) error {
	if accountRef.IsZero() {
		return merrors.InvalidArgument("account reference is required")
	}
	_, err := s.transactions.CreateTransaction().Execute(ctx, func(tx context.Context) (any, error) {
		if err := s.sessions.RevokeAll(tx, accountRef, ""); err != nil {
			return nil, err
		}
		return nil, s.accountDB.Delete(tx, accountRef)
	})
	if err != nil {
		s.logger.Warn("Customer deletion failed", zap.Error(err), mzap.AccRef(accountRef))
		return err
	}
	s.logger.Info("Customer deleted and sessions revoked", mzap.AccRef(accountRef))
	return nil
}

func (s *service) ResetPassword(
	ctx context.Context,
	acct *customermodel.Account,
) (string, error) {
	if acct == nil || acct.ID.IsZero() {
		return "", merrors.InvalidArgument("customer reference is required")
	}
	return s.vdb.Create(
		ctx,
		verification.NewOTPRequest(*acct.GetID(), verificationmodel.PurposePasswordReset, "").
			WithTTL(time.Hour),
	)
}

func (s *service) UpdateLogin(
	ctx context.Context,
	acct *customermodel.Account,
	newLogin string,
) (string, error) {
	if acct == nil || acct.ID.IsZero() {
		return "", merrors.InvalidArgument("customer reference is required")
	}
	return s.vdb.Create(
		ctx,
		verification.NewOTPRequest(*acct.GetID(), verificationmodel.PurposeEmailChange, newLogin).
			WithTTL(time.Hour),
	)
}

func NewAccountService(
	l mlogger.Logger,
	dbf db.Factory,
	config *middleware.PasswordConfig,
	storageConfig *middleware.AuthStorageConfig,
) (*service, error) {
	logger := l.Named("account_service")

	if config == nil {
		return nil, merrors.Internal("password configuration is required")
	}

	stores, err := authstorage.OpenStores(logger, dbf, storageConfig)
	if err != nil {
		return nil, err
	}
	return FromStores(l, config, stores, dbf.TransactionFactory())
}

func FromStores(l mlogger.Logger, config *middleware.PasswordConfig, stores *authstorage.Stores, transactions transaction.Factory) (*service, error) {
	if config == nil || stores == nil || transactions == nil {
		return nil, merrors.InvalidArgument("customer dependencies are required")
	}
	return &service{logger: l.Named("account_service"), config: config, accountDB: stores.Accounts,
		vdb: stores.Verification, sessions: stores.RefreshTokens, transactions: transactions}, nil
}