package account

import (
	"context"
	"database/sql"
	"fmt"
	"time"

	"github.com/go-jet/jet/v2/postgres"
	"github.com/google/uuid"

	"scrabble/backend/internal/postgres/jet/backend/table"
)

// Reasons recorded on a retained_identities row: what detached the credential from its
// account. The row is written just before the live identities row is removed, preserving
// the legal dossier (which email/vk/tg was linked, and when) even as the identity frees
// for reuse. See docs/ARCHITECTURE.md §9.1.
const (
	retainUnlink = "unlink"
	retainChange = "change"
	retainDelete = "delete"
)

// retainIdentityTx appends a retention-journal row for one identity being detached, inside
// tx. linkedAt is the identity's original creation time; detached_at defaults to now(). It
// must run in the same transaction as the identity removal, so the dossier and the live
// state can never diverge.
func retainIdentityTx(ctx context.Context, tx *sql.Tx, accountID uuid.UUID, kind, externalID string, confirmed bool, linkedAt time.Time, reason string) error {
	id, err := uuid.NewV7()
	if err != nil {
		return fmt.Errorf("account: new retained id: %w", err)
	}
	ins := table.RetainedIdentities.INSERT(
		table.RetainedIdentities.RetainedID, table.RetainedIdentities.AccountID,
		table.RetainedIdentities.Kind, table.RetainedIdentities.ExternalID,
		table.RetainedIdentities.Confirmed, table.RetainedIdentities.LinkedAt,
		table.RetainedIdentities.Reason,
	).VALUES(id, accountID, kind, externalID, confirmed, linkedAt, reason)
	if _, err := ins.ExecContext(ctx, tx); err != nil {
		return fmt.Errorf("account: retain identity (%s, %s): %w", kind, externalID, err)
	}
	return nil
}

// StampLastLogin records the account's last cold-load time and client IP, but only when
// the stored value is missing or older than an hour — so it costs at most one write per
// account per hour (its caller, the profile fetch, runs once per cold app-load). It is a
// best-effort audit signal that feeds the account-deletion dossier.
func (s *Store) StampLastLogin(ctx context.Context, accountID uuid.UUID, ip string) error {
	now := time.Now().UTC()
	upd := table.Accounts.UPDATE(table.Accounts.LastLoginAt, table.Accounts.LastLoginIP).
		SET(postgres.TimestampzT(now), postgres.String(ip)).
		WHERE(
			table.Accounts.AccountID.EQ(postgres.UUID(accountID)).
				AND(
					table.Accounts.LastLoginAt.IS_NULL().
						OR(table.Accounts.LastLoginAt.LT(postgres.TimestampzT(now.Add(-time.Hour)))),
				),
		)
	if _, err := upd.ExecContext(ctx, s.db); err != nil {
		return fmt.Errorf("account: stamp last login %s: %w", accountID, err)
	}
	return nil
}