package store

import (
	"context"
	"database/sql"
	"encoding/json"
	"errors"
	"regexp"
	"strings"
	"time"

	"yovision/sense/internal/auditrelay"
)

var relayErrorCode = regexp.MustCompile(`^[a-z][a-z0-9_]{0,63}$`)

func (s *Postgres) AuditRelayReady(ctx context.Context) error {
	var version int64
	if err := s.db.QueryRowContext(ctx, `SELECT COALESCE(MAX(version), 0) FROM sense.schema_migrations`).Scan(&version); err != nil || version < 6 {
		return errors.New("postgres Sense schema migration v6 is required for audit relay")
	}
	var canUseOutbox, canReadBell, canWriteBell bool
	if err := s.db.QueryRowContext(ctx, `SELECT
		has_table_privilege(current_user, 'sense.device_operation_outbox', 'SELECT,INSERT,UPDATE,DELETE'),
		has_table_privilege(current_user, 'bell.audit_events', 'SELECT'),
		has_table_privilege(current_user, 'bell.audit_events', 'INSERT,UPDATE,DELETE')`).Scan(
		&canUseOutbox, &canReadBell, &canWriteBell,
	); err != nil {
		return errors.New("verify audit relay privileges")
	}
	if !canUseOutbox || canReadBell || canWriteBell {
		return errors.New("Sense audit relay violates schema ownership boundary")
	}
	return nil
}

func (s *Postgres) ClaimAuditRelayBatch(
	ctx context.Context,
	owner string,
	limit int,
	lease time.Duration,
) ([]auditrelay.QueuedEvent, error) {
	if strings.TrimSpace(owner) == "" || limit < 1 || limit > auditrelay.MaxBatchSize || lease <= 0 {
		return nil, errors.New("invalid audit relay claim")
	}
	rows, err := s.db.QueryContext(ctx, `WITH due AS (
		SELECT event_id FROM sense.device_operation_outbox
		WHERE delivered_at IS NULL AND dead_lettered_at IS NULL
			AND COALESCE(next_attempt_at, available_at) <= clock_timestamp()
			AND (relay_lease_until IS NULL OR relay_lease_until <= clock_timestamp())
		ORDER BY COALESCE(next_attempt_at, available_at), event_id
		FOR UPDATE SKIP LOCKED LIMIT $1
	)
	UPDATE sense.device_operation_outbox AS outbox SET
		relay_lease_owner = $2,
		relay_lease_token = outbox.relay_lease_token + 1,
		relay_lease_until = clock_timestamp() + ($3 * interval '1 second'),
		attempt_count = outbox.attempt_count + 1,
		last_error_code = NULL
	FROM due WHERE outbox.event_id = due.event_id
	RETURNING outbox.event_id, outbox.event_type, outbox.tenant_id,
		outbox.site_id, outbox.device_id, outbox.actor_type, outbox.actor_id,
		outbox.reason, outbox.trace_id, outbox.aggregate_generation,
		outbox.quota_source_version, outbox.area_policy_source_version,
		outbox.payload, outbox.occurred_at, outbox.relay_lease_token,
		outbox.attempt_count`, limit, owner, lease.Seconds())
	if err != nil {
		return nil, errors.New("claim audit relay batch")
	}
	defer rows.Close()
	values := make([]auditrelay.QueuedEvent, 0)
	for rows.Next() {
		var value auditrelay.QueuedEvent
		var reason, trace sql.NullString
		var quota, area sql.NullInt64
		var payload []byte
		if err := rows.Scan(
			&value.Event.EventID, &value.Event.EventType, &value.Event.TenantID,
			&value.Event.SiteID, &value.Event.DeviceID, &value.Event.Actor.Type,
			&value.Event.Actor.ID, &reason, &trace, &value.Event.AggregateGeneration,
			&quota, &area, &payload, &value.Event.OccurredAt, &value.LeaseToken,
			&value.AttemptCount,
		); err != nil {
			return nil, errors.New("scan audit relay claim")
		}
		if reason.Valid {
			value.Event.Reason = &reason.String
		}
		if trace.Valid {
			value.Event.TraceID = &trace.String
		}
		if quota.Valid {
			value.Event.ProjectionVersions.QuotaSourceVersion = &quota.Int64
		}
		if area.Valid {
			value.Event.ProjectionVersions.AreaPolicySourceVersion = &area.Int64
		}
		if !json.Valid(payload) {
			return nil, errors.New("invalid audit payload in outbox")
		}
		value.Event.Data = append(json.RawMessage(nil), payload...)
		value.SchemaVersion = 1
		if value.Event.EventType == "device.configuration.accepted" {
			value.SchemaVersion = 2
		}
		values = append(values, value)
	}
	if err := rows.Err(); err != nil {
		return nil, errors.New("iterate audit relay claims")
	}
	return values, nil
}

func (s *Postgres) CompleteAuditRelayBatch(
	ctx context.Context,
	owner string,
	values []auditrelay.Completion,
) error {
	if strings.TrimSpace(owner) == "" || len(values) == 0 || len(values) > auditrelay.MaxBatchSize {
		return errors.New("invalid audit relay completion")
	}
	tx, err := s.db.BeginTx(ctx, nil)
	if err != nil {
		return errors.New("begin audit relay completion")
	}
	defer tx.Rollback()
	for _, value := range values {
		code := value.ErrorCode
		if code != "" && !relayErrorCode.MatchString(code) {
			code = "invalid_response"
		}
		var result sql.Result
		switch value.Disposition {
		case auditrelay.Delivered:
			result, err = tx.ExecContext(ctx, `UPDATE sense.device_operation_outbox SET
				delivered_at = clock_timestamp(), last_error_code = NULL,
				relay_lease_owner = NULL, relay_lease_until = NULL
			WHERE event_id = $1 AND relay_lease_owner = $2 AND relay_lease_token = $3
				AND relay_lease_until > clock_timestamp()`, value.EventID, owner, value.LeaseToken)
		case auditrelay.DeadLetter:
			if code == "" {
				return errors.New("dead-letter completion requires an error code")
			}
			result, err = tx.ExecContext(ctx, `UPDATE sense.device_operation_outbox SET
				dead_lettered_at = clock_timestamp(), last_error_code = $4,
				relay_lease_owner = NULL, relay_lease_until = NULL
			WHERE event_id = $1 AND relay_lease_owner = $2 AND relay_lease_token = $3
				AND relay_lease_until > clock_timestamp()`, value.EventID, owner, value.LeaseToken, code)
		case auditrelay.Retry:
			if code == "" || value.RetryAfter < time.Second || value.RetryAfter > 300*time.Second {
				return errors.New("invalid audit relay retry completion")
			}
			result, err = tx.ExecContext(ctx, `UPDATE sense.device_operation_outbox SET
				next_attempt_at = clock_timestamp() + ($4 * interval '1 second'),
				last_error_code = $5, relay_lease_owner = NULL, relay_lease_until = NULL
			WHERE event_id = $1 AND relay_lease_owner = $2 AND relay_lease_token = $3
				AND relay_lease_until > clock_timestamp()`, value.EventID, owner, value.LeaseToken, value.RetryAfter.Seconds(), code)
		default:
			return errors.New("invalid audit relay disposition")
		}
		if err != nil {
			return errors.New("persist audit relay completion")
		}
		affected, err := result.RowsAffected()
		if err != nil {
			return errors.New("read audit relay completion")
		}
		if affected != 1 {
			return auditrelay.ErrLeaseLost
		}
	}
	if err := tx.Commit(); err != nil {
		return errors.New("commit audit relay completion")
	}
	return nil
}