mcias/internal/db/accounts.go

package db

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

	"git.wntrmute.dev/kyle/mcias/internal/model"
	"github.com/google/uuid"
)

// CreateAccount inserts a new account record. The UUID is generated
// automatically. Returns the created Account with its DB-assigned ID and UUID.
func (db *DB) CreateAccount(username string, accountType model.AccountType, passwordHash string) (*model.Account, error) {
	id := uuid.New().String()
	n := now()

	result, err := db.sql.Exec(`
		INSERT INTO accounts (uuid, username, account_type, password_hash, status, created_at, updated_at)
		VALUES (?, ?, ?, ?, 'active', ?, ?)
	`, id, username, string(accountType), nullString(passwordHash), n, n)
	if err != nil {
		return nil, fmt.Errorf("db: create account %q: %w", username, err)
	}

	rowID, err := result.LastInsertId()
	if err != nil {
		return nil, fmt.Errorf("db: last insert id for account %q: %w", username, err)
	}

	createdAt, err := parseTime(n)
	if err != nil {
		return nil, err
	}

	return &model.Account{
		ID:           rowID,
		UUID:         id,
		Username:     username,
		AccountType:  accountType,
		Status:       model.AccountStatusActive,
		PasswordHash: passwordHash,
		CreatedAt:    createdAt,
		UpdatedAt:    createdAt,
	}, nil
}

// GetAccountByUUID retrieves an account by its external UUID.
// Returns ErrNotFound if no matching account exists.
func (db *DB) GetAccountByUUID(accountUUID string) (*model.Account, error) {
	return db.scanAccount(db.sql.QueryRow(`
		SELECT id, uuid, username, account_type, COALESCE(password_hash,''),
		       status, totp_required,
		       totp_secret_enc, totp_secret_nonce,
		       created_at, updated_at, deleted_at
		FROM accounts WHERE uuid = ?
	`, accountUUID))
}

// GetAccountByID retrieves an account by its numeric primary key.
// Returns ErrNotFound if no matching account exists.
func (db *DB) GetAccountByID(id int64) (*model.Account, error) {
	return db.scanAccount(db.sql.QueryRow(`
		SELECT id, uuid, username, account_type, COALESCE(password_hash,''),
		       status, totp_required,
		       totp_secret_enc, totp_secret_nonce,
		       created_at, updated_at, deleted_at
		FROM accounts WHERE id = ?
	`, id))
}

// GetAccountByUsername retrieves an account by username (case-insensitive).
// Returns ErrNotFound if no matching account exists.
func (db *DB) GetAccountByUsername(username string) (*model.Account, error) {
	return db.scanAccount(db.sql.QueryRow(`
		SELECT id, uuid, username, account_type, COALESCE(password_hash,''),
		       status, totp_required,
		       totp_secret_enc, totp_secret_nonce,
		       created_at, updated_at, deleted_at
		FROM accounts WHERE username = ?
	`, username))
}

// ListAccounts returns all non-deleted accounts ordered by username.
func (db *DB) ListAccounts() ([]*model.Account, error) {
	rows, err := db.sql.Query(`
		SELECT id, uuid, username, account_type, COALESCE(password_hash,''),
		       status, totp_required,
		       totp_secret_enc, totp_secret_nonce,
		       created_at, updated_at, deleted_at
		FROM accounts
		WHERE status != 'deleted'
		ORDER BY username ASC
	`)
	if err != nil {
		return nil, fmt.Errorf("db: list accounts: %w", err)
	}
	defer func() { _ = rows.Close() }()

	var accounts []*model.Account
	for rows.Next() {
		a, err := db.scanAccountRow(rows)
		if err != nil {
			return nil, err
		}
		accounts = append(accounts, a)
	}
	return accounts, rows.Err()
}

// UpdateAccountStatus updates the status field and optionally sets deleted_at.
func (db *DB) UpdateAccountStatus(accountID int64, status model.AccountStatus) error {
	n := now()
	var deletedAt *string
	if status == model.AccountStatusDeleted {
		deletedAt = &n
	}

	_, err := db.sql.Exec(`
		UPDATE accounts SET status = ?, deleted_at = ?, updated_at = ?
		WHERE id = ?
	`, string(status), deletedAt, n, accountID)
	if err != nil {
		return fmt.Errorf("db: update account status: %w", err)
	}
	return nil
}

// UpdatePasswordHash updates the Argon2id password hash for an account.
func (db *DB) UpdatePasswordHash(accountID int64, hash string) error {
	_, err := db.sql.Exec(`
		UPDATE accounts SET password_hash = ?, updated_at = ?
		WHERE id = ?
	`, hash, now(), accountID)
	if err != nil {
		return fmt.Errorf("db: update password hash: %w", err)
	}
	return nil
}

// StorePendingTOTP stores the encrypted TOTP secret without enabling the
// totp_required flag. This is called during enrollment (POST /v1/auth/totp/enroll)
// so the secret is available for confirmation without yet enforcing TOTP on login.
// The flag is set to 1 only after the user successfully confirms the code via
// handleTOTPConfirm, which calls SetTOTP.
//
// Security: keeping totp_required=0 during enrollment prevents the user from
// being locked out if they abandon the enrollment flow after the secret is
// generated but before they have set up their authenticator app.
func (db *DB) StorePendingTOTP(accountID int64, secretEnc, secretNonce []byte) error {
	_, err := db.sql.Exec(`
		UPDATE accounts
		SET totp_secret_enc = ?, totp_secret_nonce = ?, updated_at = ?
		WHERE id = ?
	`, secretEnc, secretNonce, now(), accountID)
	if err != nil {
		return fmt.Errorf("db: store pending TOTP: %w", err)
	}
	return nil
}

// SetTOTP stores the encrypted TOTP secret and marks TOTP as required.
// Call this only after the user has confirmed the TOTP code; for the initial
// enrollment step use StorePendingTOTP instead.
func (db *DB) SetTOTP(accountID int64, secretEnc, secretNonce []byte) error {
	_, err := db.sql.Exec(`
		UPDATE accounts
		SET totp_required = 1, totp_secret_enc = ?, totp_secret_nonce = ?, updated_at = ?
		WHERE id = ?
	`, secretEnc, secretNonce, now(), accountID)
	if err != nil {
		return fmt.Errorf("db: set TOTP: %w", err)
	}
	return nil
}

// ClearTOTP removes the TOTP secret and disables TOTP requirement.
func (db *DB) ClearTOTP(accountID int64) error {
	_, err := db.sql.Exec(`
		UPDATE accounts
		SET totp_required = 0, totp_secret_enc = NULL, totp_secret_nonce = NULL, updated_at = ?
		WHERE id = ?
	`, now(), accountID)
	if err != nil {
		return fmt.Errorf("db: clear TOTP: %w", err)
	}
	return nil
}

// scanAccount scans a single account row from a *sql.Row.
func (db *DB) scanAccount(row *sql.Row) (*model.Account, error) {
	var a model.Account
	var accountType, status string
	var totpRequired int
	var createdAtStr, updatedAtStr string
	var deletedAtStr *string
	var totpSecretEnc, totpSecretNonce []byte

	err := row.Scan(
		&a.ID, &a.UUID, &a.Username,
		&accountType, &a.PasswordHash,
		&status, &totpRequired,
		&totpSecretEnc, &totpSecretNonce,
		&createdAtStr, &updatedAtStr, &deletedAtStr,
	)
	if errors.Is(err, sql.ErrNoRows) {
		return nil, ErrNotFound
	}
	if err != nil {
		return nil, fmt.Errorf("db: scan account: %w", err)
	}

	return finishAccountScan(&a, accountType, status, totpRequired, totpSecretEnc, totpSecretNonce, createdAtStr, updatedAtStr, deletedAtStr)
}

// scanAccountRow scans a single account from *sql.Rows.
func (db *DB) scanAccountRow(rows *sql.Rows) (*model.Account, error) {
	var a model.Account
	var accountType, status string
	var totpRequired int
	var createdAtStr, updatedAtStr string
	var deletedAtStr *string
	var totpSecretEnc, totpSecretNonce []byte

	err := rows.Scan(
		&a.ID, &a.UUID, &a.Username,
		&accountType, &a.PasswordHash,
		&status, &totpRequired,
		&totpSecretEnc, &totpSecretNonce,
		&createdAtStr, &updatedAtStr, &deletedAtStr,
	)
	if err != nil {
		return nil, fmt.Errorf("db: scan account row: %w", err)
	}

	return finishAccountScan(&a, accountType, status, totpRequired, totpSecretEnc, totpSecretNonce, createdAtStr, updatedAtStr, deletedAtStr)
}

func finishAccountScan(a *model.Account, accountType, status string, totpRequired int, totpSecretEnc, totpSecretNonce []byte, createdAtStr, updatedAtStr string, deletedAtStr *string) (*model.Account, error) {
	a.AccountType = model.AccountType(accountType)
	a.Status = model.AccountStatus(status)
	a.TOTPRequired = totpRequired == 1
	a.TOTPSecretEnc = totpSecretEnc
	a.TOTPSecretNonce = totpSecretNonce

	var err error
	a.CreatedAt, err = parseTime(createdAtStr)
	if err != nil {
		return nil, err
	}
	a.UpdatedAt, err = parseTime(updatedAtStr)
	if err != nil {
		return nil, err
	}
	a.DeletedAt, err = nullableTime(deletedAtStr)
	if err != nil {
		return nil, err
	}
	return a, nil
}

// nullString converts an empty string to nil for nullable SQL columns.
func nullString(s string) *string {
	if s == "" {
		return nil
	}
	return &s
}

// GetRoles returns the role strings assigned to an account.
func (db *DB) GetRoles(accountID int64) ([]string, error) {
	rows, err := db.sql.Query(`
		SELECT role FROM account_roles WHERE account_id = ? ORDER BY role ASC
	`, accountID)
	if err != nil {
		return nil, fmt.Errorf("db: get roles for account %d: %w", accountID, err)
	}
	defer func() { _ = rows.Close() }()

	var roles []string
	for rows.Next() {
		var role string
		if err := rows.Scan(&role); err != nil {
			return nil, fmt.Errorf("db: scan role: %w", err)
		}
		roles = append(roles, role)
	}
	return roles, rows.Err()
}

// GrantRole adds a role to an account. If the role already exists, it is a no-op.
func (db *DB) GrantRole(accountID int64, role string, grantedBy *int64) error {
	_, err := db.sql.Exec(`
		INSERT OR IGNORE INTO account_roles (account_id, role, granted_by, granted_at)
		VALUES (?, ?, ?, ?)
	`, accountID, role, grantedBy, now())
	if err != nil {
		return fmt.Errorf("db: grant role %q to account %d: %w", role, accountID, err)
	}
	return nil
}

// RevokeRole removes a role from an account.
func (db *DB) RevokeRole(accountID int64, role string) error {
	_, err := db.sql.Exec(`
		DELETE FROM account_roles WHERE account_id = ? AND role = ?
	`, accountID, role)
	if err != nil {
		return fmt.Errorf("db: revoke role %q from account %d: %w", role, accountID, err)
	}
	return nil
}

// SetRoles replaces the full role set for an account atomically.
func (db *DB) SetRoles(accountID int64, roles []string, grantedBy *int64) error {
	tx, err := db.sql.Begin()
	if err != nil {
		return fmt.Errorf("db: set roles begin tx: %w", err)
	}

	if _, err := tx.Exec(`DELETE FROM account_roles WHERE account_id = ?`, accountID); err != nil {
		_ = tx.Rollback()
		return fmt.Errorf("db: set roles delete existing: %w", err)
	}

	n := now()
	for _, role := range roles {
		if _, err := tx.Exec(`
			INSERT INTO account_roles (account_id, role, granted_by, granted_at)
			VALUES (?, ?, ?, ?)
		`, accountID, role, grantedBy, n); err != nil {
			_ = tx.Rollback()
			return fmt.Errorf("db: set roles insert %q: %w", role, err)
		}
	}

	if err := tx.Commit(); err != nil {
		return fmt.Errorf("db: set roles commit: %w", err)
	}
	return nil
}

// HasRole reports whether an account holds the given role.
func (db *DB) HasRole(accountID int64, role string) (bool, error) {
	var count int
	err := db.sql.QueryRow(`
		SELECT COUNT(*) FROM account_roles WHERE account_id = ? AND role = ?
	`, accountID, role).Scan(&count)
	if err != nil {
		return false, fmt.Errorf("db: has role: %w", err)
	}
	return count > 0, nil
}

// WriteServerConfig stores the encrypted Ed25519 signing key.
// There can only be one row (id=1).
func (db *DB) WriteServerConfig(signingKeyEnc, signingKeyNonce []byte) error {
	n := now()
	_, err := db.sql.Exec(`
		INSERT INTO server_config (id, signing_key_enc, signing_key_nonce, created_at, updated_at)
		VALUES (1, ?, ?, ?, ?)
		ON CONFLICT(id) DO UPDATE SET
			signing_key_enc   = excluded.signing_key_enc,
			signing_key_nonce = excluded.signing_key_nonce,
			updated_at        = excluded.updated_at
	`, signingKeyEnc, signingKeyNonce, n, n)
	if err != nil {
		return fmt.Errorf("db: write server config: %w", err)
	}
	return nil
}

// ReadServerConfig returns the encrypted signing key and nonce.
// Returns ErrNotFound if no config row exists yet.
func (db *DB) ReadServerConfig() (signingKeyEnc, signingKeyNonce []byte, err error) {
	err = db.sql.QueryRow(`
		SELECT signing_key_enc, signing_key_nonce FROM server_config WHERE id = 1
	`).Scan(&signingKeyEnc, &signingKeyNonce)
	if errors.Is(err, sql.ErrNoRows) {
		return nil, nil, ErrNotFound
	}
	if err != nil {
		return nil, nil, fmt.Errorf("db: read server config: %w", err)
	}
	return signingKeyEnc, signingKeyNonce, nil
}

// WriteMasterKeySalt stores the Argon2id KDF salt for the master key derivation.
// The salt must be stable across restarts so the same passphrase always yields
// the same master key. There can only be one row (id=1).
func (db *DB) WriteMasterKeySalt(salt []byte) error {
	n := now()
	_, err := db.sql.Exec(`
		INSERT INTO server_config (id, master_key_salt, created_at, updated_at)
		VALUES (1, ?, ?, ?)
		ON CONFLICT(id) DO UPDATE SET
			master_key_salt = excluded.master_key_salt,
			updated_at      = excluded.updated_at
	`, salt, n, n)
	if err != nil {
		return fmt.Errorf("db: write master key salt: %w", err)
	}
	return nil
}

// ReadMasterKeySalt returns the stored Argon2id KDF salt.
// Returns ErrNotFound if no salt has been stored yet (first run).
func (db *DB) ReadMasterKeySalt() ([]byte, error) {
	var salt []byte
	err := db.sql.QueryRow(`
		SELECT master_key_salt FROM server_config WHERE id = 1
	`).Scan(&salt)
	if errors.Is(err, sql.ErrNoRows) {
		return nil, ErrNotFound
	}
	if err != nil {
		return nil, fmt.Errorf("db: read master key salt: %w", err)
	}
	if salt == nil {
		return nil, ErrNotFound
	}
	return salt, nil
}

// WritePGCredentials stores or replaces the Postgres credentials for an account.
func (db *DB) WritePGCredentials(accountID int64, host string, port int, dbName, username string, passwordEnc, passwordNonce []byte) error {
	n := now()
	_, err := db.sql.Exec(`
		INSERT INTO pg_credentials
			(account_id, pg_host, pg_port, pg_database, pg_username, pg_password_enc, pg_password_nonce, created_at, updated_at)
		VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)
		ON CONFLICT(account_id) DO UPDATE SET
			pg_host           = excluded.pg_host,
			pg_port           = excluded.pg_port,
			pg_database       = excluded.pg_database,
			pg_username       = excluded.pg_username,
			pg_password_enc   = excluded.pg_password_enc,
			pg_password_nonce = excluded.pg_password_nonce,
			updated_at        = excluded.updated_at
	`, accountID, host, port, dbName, username, passwordEnc, passwordNonce, n, n)
	if err != nil {
		return fmt.Errorf("db: write pg credentials: %w", err)
	}
	return nil
}

// ReadPGCredentials retrieves the encrypted Postgres credentials for an account.
// Returns ErrNotFound if no credentials are stored.
func (db *DB) ReadPGCredentials(accountID int64) (*model.PGCredential, error) {
	var cred model.PGCredential
	var createdAtStr, updatedAtStr string

	err := db.sql.QueryRow(`
		SELECT id, account_id, pg_host, pg_port, pg_database, pg_username,
		       pg_password_enc, pg_password_nonce, created_at, updated_at
		FROM pg_credentials WHERE account_id = ?
	`, accountID).Scan(
		&cred.ID, &cred.AccountID, &cred.PGHost, &cred.PGPort,
		&cred.PGDatabase, &cred.PGUsername,
		&cred.PGPasswordEnc, &cred.PGPasswordNonce,
		&createdAtStr, &updatedAtStr,
	)
	if errors.Is(err, sql.ErrNoRows) {
		return nil, ErrNotFound
	}
	if err != nil {
		return nil, fmt.Errorf("db: read pg credentials: %w", err)
	}

	cred.CreatedAt, err = parseTime(createdAtStr)
	if err != nil {
		return nil, err
	}
	cred.UpdatedAt, err = parseTime(updatedAtStr)
	if err != nil {
		return nil, err
	}
	return &cred, nil
}

// WriteAuditEvent appends an audit log entry.
// Details must never contain credential material.
func (db *DB) WriteAuditEvent(eventType string, actorID, targetID *int64, ipAddress, details string) error {
	_, err := db.sql.Exec(`
		INSERT INTO audit_log (event_type, actor_id, target_id, ip_address, details)
		VALUES (?, ?, ?, ?, ?)
	`, eventType, actorID, targetID, nullString(ipAddress), nullString(details))
	if err != nil {
		return fmt.Errorf("db: write audit event %q: %w", eventType, err)
	}
	return nil
}

// TrackToken records a newly issued JWT JTI for revocation tracking.
func (db *DB) TrackToken(jti string, accountID int64, issuedAt, expiresAt time.Time) error {
	_, err := db.sql.Exec(`
		INSERT INTO token_revocation (jti, account_id, issued_at, expires_at)
		VALUES (?, ?, ?, ?)
	`, jti, accountID, issuedAt.UTC().Format(time.RFC3339), expiresAt.UTC().Format(time.RFC3339))
	if err != nil {
		return fmt.Errorf("db: track token %q: %w", jti, err)
	}
	return nil
}

// GetTokenRecord retrieves a token record by JTI.
// Returns ErrNotFound if no record exists (token was never issued by this server).
func (db *DB) GetTokenRecord(jti string) (*model.TokenRecord, error) {
	var rec model.TokenRecord
	var issuedAtStr, expiresAtStr, createdAtStr string
	var revokedAtStr *string
	var revokeReason *string

	err := db.sql.QueryRow(`
		SELECT id, jti, account_id, expires_at, issued_at, revoked_at, revoke_reason, created_at
		FROM token_revocation WHERE jti = ?
	`, jti).Scan(
		&rec.ID, &rec.JTI, &rec.AccountID,
		&expiresAtStr, &issuedAtStr, &revokedAtStr, &revokeReason,
		&createdAtStr,
	)
	if errors.Is(err, sql.ErrNoRows) {
		return nil, ErrNotFound
	}
	if err != nil {
		return nil, fmt.Errorf("db: get token record %q: %w", jti, err)
	}

	var parseErr error
	rec.ExpiresAt, parseErr = parseTime(expiresAtStr)
	if parseErr != nil {
		return nil, parseErr
	}
	rec.IssuedAt, parseErr = parseTime(issuedAtStr)
	if parseErr != nil {
		return nil, parseErr
	}
	rec.CreatedAt, parseErr = parseTime(createdAtStr)
	if parseErr != nil {
		return nil, parseErr
	}
	rec.RevokedAt, parseErr = nullableTime(revokedAtStr)
	if parseErr != nil {
		return nil, parseErr
	}
	if revokeReason != nil {
		rec.RevokeReason = *revokeReason
	}
	return &rec, nil
}

// RevokeToken marks a token as revoked by JTI.
func (db *DB) RevokeToken(jti, reason string) error {
	n := now()
	result, err := db.sql.Exec(`
		UPDATE token_revocation
		SET revoked_at = ?, revoke_reason = ?
		WHERE jti = ? AND revoked_at IS NULL
	`, n, nullString(reason), jti)
	if err != nil {
		return fmt.Errorf("db: revoke token %q: %w", jti, err)
	}
	rows, err := result.RowsAffected()
	if err != nil {
		return fmt.Errorf("db: revoke token rows affected: %w", err)
	}
	if rows == 0 {
		return fmt.Errorf("db: token %q not found or already revoked", jti)
	}
	return nil
}

// RenewToken atomically revokes the old token and tracks the new one in a
// single SQLite transaction.
//
// Security: the two operations must be atomic so that a failure between them
// cannot leave the user with neither a valid old token nor a new one.  With
// MaxOpenConns(1) and SQLite's serialised write path, BEGIN IMMEDIATE acquires
// the write lock immediately and prevents any other writer from interleaving.
func (db *DB) RenewToken(oldJTI, reason, newJTI string, accountID int64, issuedAt, expiresAt time.Time) error {
	tx, err := db.sql.Begin()
	if err != nil {
		return fmt.Errorf("db: renew token begin tx: %w", err)
	}
	defer func() { _ = tx.Rollback() }()

	n := now()

	// Revoke the old token.
	result, err := tx.Exec(`
		UPDATE token_revocation
		SET revoked_at = ?, revoke_reason = ?
		WHERE jti = ? AND revoked_at IS NULL
	`, n, nullString(reason), oldJTI)
	if err != nil {
		return fmt.Errorf("db: renew token revoke old %q: %w", oldJTI, err)
	}
	rows, err := result.RowsAffected()
	if err != nil {
		return fmt.Errorf("db: renew token revoke rows affected: %w", err)
	}
	if rows == 0 {
		return fmt.Errorf("db: renew token: old token %q not found or already revoked", oldJTI)
	}

	// Track the new token.
	_, err = tx.Exec(`
		INSERT INTO token_revocation (jti, account_id, issued_at, expires_at)
		VALUES (?, ?, ?, ?)
	`, newJTI, accountID,
		issuedAt.UTC().Format(time.RFC3339),
		expiresAt.UTC().Format(time.RFC3339))
	if err != nil {
		return fmt.Errorf("db: renew token track new %q: %w", newJTI, err)
	}

	if err := tx.Commit(); err != nil {
		return fmt.Errorf("db: renew token commit: %w", err)
	}
	return nil
}

// RevokeAllUserTokens revokes all non-expired, non-revoked tokens for an account.
func (db *DB) RevokeAllUserTokens(accountID int64, reason string) error {
	n := now()
	_, err := db.sql.Exec(`
		UPDATE token_revocation
		SET revoked_at = ?, revoke_reason = ?
		WHERE account_id = ? AND revoked_at IS NULL AND expires_at > ?
	`, n, nullString(reason), accountID, n)
	if err != nil {
		return fmt.Errorf("db: revoke all tokens for account %d: %w", accountID, err)
	}
	return nil
}

// PruneExpiredTokens removes token_revocation rows that are past their expiry.
// Returns the number of rows deleted.
func (db *DB) PruneExpiredTokens() (int64, error) {
	result, err := db.sql.Exec(`
		DELETE FROM token_revocation WHERE expires_at < ?
	`, now())
	if err != nil {
		return 0, fmt.Errorf("db: prune expired tokens: %w", err)
	}
	return result.RowsAffected()
}

// ListTokensForAccount returns all token_revocation rows for the given account,
// ordered by issued_at descending (newest first).
func (db *DB) ListTokensForAccount(accountID int64) ([]*model.TokenRecord, error) {
	rows, err := db.sql.Query(`
		SELECT id, jti, account_id, expires_at, issued_at, revoked_at, revoke_reason, created_at
		FROM token_revocation
		WHERE account_id = ?
		ORDER BY issued_at DESC
	`, accountID)
	if err != nil {
		return nil, fmt.Errorf("db: list tokens for account %d: %w", accountID, err)
	}
	defer func() { _ = rows.Close() }()

	var records []*model.TokenRecord
	for rows.Next() {
		var rec model.TokenRecord
		var issuedAtStr, expiresAtStr, createdAtStr string
		var revokedAtStr *string
		var revokeReason *string

		if err := rows.Scan(
			&rec.ID, &rec.JTI, &rec.AccountID,
			&expiresAtStr, &issuedAtStr, &revokedAtStr, &revokeReason,
			&createdAtStr,
		); err != nil {
			return nil, fmt.Errorf("db: scan token record: %w", err)
		}

		var parseErr error
		rec.ExpiresAt, parseErr = parseTime(expiresAtStr)
		if parseErr != nil {
			return nil, parseErr
		}
		rec.IssuedAt, parseErr = parseTime(issuedAtStr)
		if parseErr != nil {
			return nil, parseErr
		}
		rec.CreatedAt, parseErr = parseTime(createdAtStr)
		if parseErr != nil {
			return nil, parseErr
		}
		rec.RevokedAt, parseErr = nullableTime(revokedAtStr)
		if parseErr != nil {
			return nil, parseErr
		}
		if revokeReason != nil {
			rec.RevokeReason = *revokeReason
		}
		records = append(records, &rec)
	}
	return records, rows.Err()
}

// AuditQueryParams filters for ListAuditEvents and ListAuditEventsPaged.
type AuditQueryParams struct {
	AccountID *int64
	Since     *time.Time
	EventType string
	Limit     int
	Offset    int
}

// AuditEventView extends AuditEvent with resolved actor/target usernames for display.
// Usernames are resolved via a LEFT JOIN and are empty if the actor/target is unknown.
// The fieldalignment hint is suppressed: the embedded model.AuditEvent layout is fixed
// and changing to explicit fields would break JSON serialisation.
type AuditEventView struct { //nolint:govet
	model.AuditEvent
	ActorUsername  string `json:"actor_username,omitempty"`
	TargetUsername string `json:"target_username,omitempty"`
}

// ListAuditEvents returns audit log entries matching the given parameters,
// ordered by event_time ascending. Limit rows are returned if Limit > 0.
func (db *DB) ListAuditEvents(p AuditQueryParams) ([]*model.AuditEvent, error) {
	query := `
		SELECT id, event_time, event_type, actor_id, target_id, ip_address, details
		FROM audit_log
		WHERE 1=1
	`
	args := []interface{}{}

	if p.AccountID != nil {
		query += ` AND (actor_id = ? OR target_id = ?)`
		args = append(args, *p.AccountID, *p.AccountID)
	}
	if p.EventType != "" {
		query += ` AND event_type = ?`
		args = append(args, p.EventType)
	}
	if p.Since != nil {
		query += ` AND event_time >= ?`
		args = append(args, p.Since.UTC().Format(time.RFC3339))
	}

	query += ` ORDER BY event_time ASC, id ASC`

	if p.Limit > 0 {
		query += ` LIMIT ?`
		args = append(args, p.Limit)
	}

	rows, err := db.sql.Query(query, args...)
	if err != nil {
		return nil, fmt.Errorf("db: list audit events: %w", err)
	}
	defer func() { _ = rows.Close() }()

	var events []*model.AuditEvent
	for rows.Next() {
		var ev model.AuditEvent
		var eventTimeStr string
		var ipAddr, details *string

		if err := rows.Scan(
			&ev.ID, &eventTimeStr, &ev.EventType,
			&ev.ActorID, &ev.TargetID,
			&ipAddr, &details,
		); err != nil {
			return nil, fmt.Errorf("db: scan audit event: %w", err)
		}

		ev.EventTime, err = parseTime(eventTimeStr)
		if err != nil {
			return nil, err
		}
		if ipAddr != nil {
			ev.IPAddress = *ipAddr
		}
		if details != nil {
			ev.Details = *details
		}
		events = append(events, &ev)
	}
	return events, rows.Err()
}

// TailAuditEvents returns the last n audit log entries, ordered oldest-first.
func (db *DB) TailAuditEvents(n int) ([]*model.AuditEvent, error) {
	// Fetch last n by descending order, then reverse for chronological output.
	rows, err := db.sql.Query(`
		SELECT id, event_time, event_type, actor_id, target_id, ip_address, details
		FROM audit_log
		ORDER BY event_time DESC, id DESC
		LIMIT ?
	`, n)
	if err != nil {
		return nil, fmt.Errorf("db: tail audit events: %w", err)
	}
	defer func() { _ = rows.Close() }()

	var events []*model.AuditEvent
	for rows.Next() {
		var ev model.AuditEvent
		var eventTimeStr string
		var ipAddr, details *string

		if err := rows.Scan(
			&ev.ID, &eventTimeStr, &ev.EventType,
			&ev.ActorID, &ev.TargetID,
			&ipAddr, &details,
		); err != nil {
			return nil, fmt.Errorf("db: scan audit event: %w", err)
		}

		var parseErr error
		ev.EventTime, parseErr = parseTime(eventTimeStr)
		if parseErr != nil {
			return nil, parseErr
		}
		if ipAddr != nil {
			ev.IPAddress = *ipAddr
		}
		if details != nil {
			ev.Details = *details
		}
		events = append(events, &ev)
	}
	if err := rows.Err(); err != nil {
		return nil, err
	}

	// Reverse to oldest-first.
	for i, j := 0, len(events)-1; i < j; i, j = i+1, j-1 {
		events[i], events[j] = events[j], events[i]
	}
	return events, nil
}

// ListAuditEventsPaged returns audit log entries matching params, newest first,
// with LEFT JOINed actor/target usernames for display. Returns the matching rows
// and the total count of matching rows (for pagination).
//
// Security: No credential material is included in audit_log rows per the
// WriteAuditEvent contract; joining account usernames is safe for display.
func (db *DB) ListAuditEventsPaged(p AuditQueryParams) ([]*AuditEventView, int64, error) {
	// Build the shared WHERE clause and args.
	where := " WHERE 1=1"
	args := []interface{}{}

	if p.AccountID != nil {
		where += ` AND (al.actor_id = ? OR al.target_id = ?)`
		args = append(args, *p.AccountID, *p.AccountID)
	}
	if p.EventType != "" {
		where += ` AND al.event_type = ?`
		args = append(args, p.EventType)
	}
	if p.Since != nil {
		where += ` AND al.event_time >= ?`
		args = append(args, p.Since.UTC().Format(time.RFC3339))
	}

	// Count total matching rows first.
	countQuery := `SELECT COUNT(*) FROM audit_log al` + where
	var total int64
	if err := db.sql.QueryRow(countQuery, args...).Scan(&total); err != nil {
		return nil, 0, fmt.Errorf("db: count audit events: %w", err)
	}

	// Fetch the page with username resolution via LEFT JOIN.
	query := `
		SELECT al.id, al.event_time, al.event_type,
		       al.actor_id, al.target_id,
		       al.ip_address, al.details,
		       COALESCE(a1.username, ''), COALESCE(a2.username, '')
		FROM audit_log al
		LEFT JOIN accounts a1 ON al.actor_id = a1.id
		LEFT JOIN accounts a2 ON al.target_id = a2.id` + where + `
		ORDER BY al.event_time DESC, al.id DESC`

	pageArgs := append(args, p.Limit, p.Offset) //nolint:gocritic // intentional new slice
	query += ` LIMIT ? OFFSET ?`

	rows, err := db.sql.Query(query, pageArgs...)
	if err != nil {
		return nil, 0, fmt.Errorf("db: list audit events paged: %w", err)
	}
	defer func() { _ = rows.Close() }()

	var events []*AuditEventView
	for rows.Next() {
		var ev AuditEventView
		var eventTimeStr string
		var ipAddr, details *string

		if err := rows.Scan(
			&ev.ID, &eventTimeStr, &ev.EventType,
			&ev.ActorID, &ev.TargetID,
			&ipAddr, &details,
			&ev.ActorUsername, &ev.TargetUsername,
		); err != nil {
			return nil, 0, fmt.Errorf("db: scan audit event view: %w", err)
		}

		ev.EventTime, err = parseTime(eventTimeStr)
		if err != nil {
			return nil, 0, err
		}
		if ipAddr != nil {
			ev.IPAddress = *ipAddr
		}
		if details != nil {
			ev.Details = *details
		}
		events = append(events, &ev)
	}
	if err := rows.Err(); err != nil {
		return nil, 0, err
	}
	return events, total, nil
}

// GetAuditEventByID fetches a single audit event by its integer primary key,
// with actor/target usernames resolved via LEFT JOIN. Returns ErrNotFound if
// no row matches.
func (db *DB) GetAuditEventByID(id int64) (*AuditEventView, error) {
	row := db.sql.QueryRow(`
		SELECT al.id, al.event_time, al.event_type,
		       al.actor_id, al.target_id,
		       al.ip_address, al.details,
		       COALESCE(a1.username, ''), COALESCE(a2.username, '')
		FROM audit_log al
		LEFT JOIN accounts a1 ON al.actor_id = a1.id
		LEFT JOIN accounts a2 ON al.target_id = a2.id
		WHERE al.id = ?
	`, id)

	var ev AuditEventView
	var eventTimeStr string
	var ipAddr, details *string

	if err := row.Scan(
		&ev.ID, &eventTimeStr, &ev.EventType,
		&ev.ActorID, &ev.TargetID,
		&ipAddr, &details,
		&ev.ActorUsername, &ev.TargetUsername,
	); err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			return nil, ErrNotFound
		}
		return nil, fmt.Errorf("db: get audit event %d: %w", id, err)
	}

	var err error
	ev.EventTime, err = parseTime(eventTimeStr)
	if err != nil {
		return nil, err
	}
	if ipAddr != nil {
		ev.IPAddress = *ipAddr
	}
	if details != nil {
		ev.Details = *details
	}
	return &ev, nil
}

// SetSystemToken stores or replaces the active service token JTI for a system account.
func (db *DB) SetSystemToken(accountID int64, jti string, expiresAt time.Time) error {
	n := now()
	_, err := db.sql.Exec(`
		INSERT INTO system_tokens (account_id, jti, expires_at, created_at)
		VALUES (?, ?, ?, ?)
		ON CONFLICT(account_id) DO UPDATE SET
			jti        = excluded.jti,
			expires_at = excluded.expires_at,
			created_at = excluded.created_at
	`, accountID, jti, expiresAt.UTC().Format(time.RFC3339), n)
	if err != nil {
		return fmt.Errorf("db: set system token for account %d: %w", accountID, err)
	}
	return nil
}

// GetSystemToken retrieves the active service token record for a system account.
func (db *DB) GetSystemToken(accountID int64) (*model.SystemToken, error) {
	var st model.SystemToken
	var expiresAtStr, createdAtStr string

	err := db.sql.QueryRow(`
		SELECT id, account_id, jti, expires_at, created_at
		FROM system_tokens WHERE account_id = ?
	`, accountID).Scan(&st.ID, &st.AccountID, &st.JTI, &expiresAtStr, &createdAtStr)
	if errors.Is(err, sql.ErrNoRows) {
		return nil, ErrNotFound
	}
	if err != nil {
		return nil, fmt.Errorf("db: get system token: %w", err)
	}

	var parseErr error
	st.ExpiresAt, parseErr = parseTime(expiresAtStr)
	if parseErr != nil {
		return nil, parseErr
	}
	st.CreatedAt, parseErr = parseTime(createdAtStr)
	if parseErr != nil {
		return nil, parseErr
	}
	return &st, nil
}