package accounts

import (
	"context"
	"database/sql"
	"errors"
	"fmt"
	"strings"
)

type txQueryer interface {
	QueryRowContext(context.Context, string, ...any) *sql.Row
	ExecContext(context.Context, string, ...any) (sql.Result, error)
}

func (s *Store) UpsertCheckout(ctx context.Context, input CheckoutInput) (*Account, *Instance, error) {
	email := strings.ToLower(strings.TrimSpace(input.Email))
	if input.StripeCustomerID == "" {
		return nil, nil, errors.New("Stripe customer id is required")
	}
	if email == "" && input.AccountID == 0 {
		return nil, nil, errors.New("email is required when account id is missing")
	}
	tx, err := s.db.BeginTx(ctx, nil)
	if err != nil {
		return nil, nil, err
	}
	defer tx.Rollback()

	if input.StripeEventID != "" {
		if processed, err := eventProcessed(ctx, tx, input.StripeEventID); err != nil {
			return nil, nil, err
		} else if processed {
			acct, inst, loadErr := s.accountAndInstanceByStripeTx(ctx, tx, input.StripeCustomerID)
			if loadErr != nil {
				return nil, nil, loadErr
			}
			return acct, inst, tx.Commit()
		}
	}

	var acct *Account
	if input.AccountID > 0 {
		acct, err = accountByID(ctx, tx, input.AccountID)
	}
	if acct == nil && (input.AccountID == 0 || errors.Is(err, ErrNotFound)) {
		acct, err = accountByStripeCustomerID(ctx, tx, input.StripeCustomerID)
	}
	if errors.Is(err, ErrNotFound) {
		acct, err = upsertCheckoutAccount(ctx, tx, input)
	}
	if err != nil {
		return nil, nil, err
	}
	if email == "" {
		input.Email = acct.PrimaryEmail
		email = strings.ToLower(strings.TrimSpace(input.Email))
	}
	if input.DisplayName == "" {
		input.DisplayName = acct.DisplayName
	}
	if err := updateCheckoutAccount(ctx, tx, acct.ID, input); err != nil {
		return nil, nil, err
	}
	if err := linkIdentity(ctx, tx, acct.ID, "stripe", input.StripeCustomerID, email); err != nil {
		return nil, nil, err
	}
	inst, err := ensureInstance(ctx, tx, acct.ID, email, input.CustomerDomain)
	if err != nil {
		return nil, nil, err
	}
	if input.StripeEventID != "" {
		if err := insertBillingEvent(ctx, tx, input, "checkout.session.completed"); err != nil {
			return nil, nil, err
		}
	}
	return acct, inst, tx.Commit()
}

func (s *Store) AccountByStripeCustomerID(ctx context.Context, customerID string) (*Account, *Instance, error) {
	return s.accountAndInstanceByStripeTx(ctx, s.db, customerID)
}

func (s *Store) MarkSubscriptionStatus(ctx context.Context, customerID, status string) error {
	res, err := s.db.ExecContext(ctx, `
		UPDATE accounts
		SET subscription_status = $2, updated_at = now()
		WHERE stripe_customer_id = $1
	`, customerID, status)
	if err != nil {
		return err
	}
	n, _ := res.RowsAffected()
	if n == 0 {
		return ErrNotFound
	}
	return nil
}

func (s *Store) InstanceByAccountID(ctx context.Context, accountID int64) (*Instance, error) {
	return instanceByAccountID(ctx, s.db, accountID)
}

func (s *Store) InstanceBySlug(ctx context.Context, slug string) (*Instance, error) {
	return instanceBySlug(ctx, s.db, slug)
}

func (s *Store) UpdateInstanceState(ctx context.Context, stackName, state string, deployed bool) error {
	q := `UPDATE instances SET state = $2, updated_at = now()`
	args := []any{stackName, state}
	if deployed {
		q += `, last_deployed_at = now()`
	}
	q += ` WHERE stack_name = $1`
	_, err := s.db.ExecContext(ctx, q, args...)
	return err
}

func (s *Store) DeleteAccountByInstanceSlug(ctx context.Context, slug string) (*Instance, error) {
	inst, err := instanceBySlug(ctx, s.db, slug)
	if err != nil {
		return nil, err
	}
	_, err = s.db.ExecContext(ctx, `DELETE FROM accounts WHERE id = $1`, inst.AccountID)
	return inst, err
}

func upsertCheckoutAccount(ctx context.Context, q txQueryer, input CheckoutInput) (*Account, error) {
	return scanAccount(q.QueryRowContext(ctx, `
		INSERT INTO accounts (primary_email, display_name, phone, stripe_customer_id, subscription_status)
		VALUES ($1, $2, $3, $4, 'active')
		ON CONFLICT (primary_email) DO UPDATE SET
			display_name = COALESCE(NULLIF(EXCLUDED.display_name, ''), accounts.display_name),
			phone = COALESCE(NULLIF(EXCLUDED.phone, ''), accounts.phone),
			stripe_customer_id = EXCLUDED.stripe_customer_id,
			subscription_status = 'active',
			updated_at = now()
		RETURNING id, primary_email, display_name, stripe_customer_id, subscription_status, created_at, updated_at
	`, strings.ToLower(input.Email), input.DisplayName, input.Phone, input.StripeCustomerID))
}

func updateCheckoutAccount(ctx context.Context, q txQueryer, accountID int64, input CheckoutInput) error {
	_, err := q.ExecContext(ctx, `
		UPDATE accounts
		SET primary_email = COALESCE(NULLIF($2, ''), primary_email),
			display_name = COALESCE(NULLIF($3, ''), display_name),
			phone = COALESCE(NULLIF($4, ''), phone),
			stripe_customer_id = COALESCE(NULLIF($5, ''), stripe_customer_id),
			subscription_status = 'active',
			updated_at = now()
		WHERE id = $1
	`, accountID, strings.ToLower(input.Email), input.DisplayName, input.Phone, input.StripeCustomerID)
	return err
}

func (s *Store) accountAndInstanceByStripeTx(ctx context.Context, q txQueryer, customerID string) (*Account, *Instance, error) {
	acct, err := accountByStripeCustomerID(ctx, q, customerID)
	if err != nil {
		return nil, nil, err
	}
	inst, err := instanceByAccountID(ctx, q, acct.ID)
	return acct, inst, err
}

func accountByStripeCustomerID(ctx context.Context, q txQueryer, customerID string) (*Account, error) {
	return scanAccount(q.QueryRowContext(ctx, `
		SELECT id, primary_email, display_name, stripe_customer_id, subscription_status, created_at, updated_at
		FROM accounts WHERE stripe_customer_id = $1
	`, customerID))
}

func ensureInstance(ctx context.Context, q txQueryer, accountID int64, email, domain string) (*Instance, error) {
	if inst, err := instanceByAccountID(ctx, q, accountID); err == nil {
		if domain != "" && inst.CustomerDomain != domain {
			_, _ = q.ExecContext(ctx, `UPDATE instances SET customer_domain = $2, updated_at = now() WHERE id = $1`, inst.ID, domain)
			inst.CustomerDomain = domain
		}
		return inst, nil
	} else if !errors.Is(err, ErrNotFound) {
		return nil, err
	}
	slug := SlugFromEmail(email)
	if owner, err := instanceBySlug(ctx, q, slug); err == nil && owner.AccountID != accountID {
		slug = fmt.Sprintf("%s-%d", slug, accountID)
	}
	stackName := "customer-" + slug
	return scanInstance(q.QueryRowContext(ctx, `
		INSERT INTO instances (account_id, slug, stack_name, customer_domain, state)
		VALUES ($1, $2, $3, $4, 'pending')
		RETURNING id, account_id, slug, stack_name, customer_domain, state, last_deployed_at
	`, accountID, slug, stackName, domain))
}