package onboarding

import (
	"context"
	"errors"

	"github.com/jackc/pgx/v5"
)

// Join the direct-call transaction fence before taking the same twin/device
// lock order as commands and OTA. A new prepare cannot race the final idle check.
func lockBLEControl(ctx context.Context, tx pgx.Tx, deviceID, factoryID string) error {
	if deviceID == "" {
		err := tx.QueryRow(ctx, `SELECT id::text FROM device WHERE factory_device_id=$1`, factoryID).Scan(&deviceID)
		if errors.Is(err, pgx.ErrNoRows) {
			return nil
		} // Normal access validation supplies the precise error.
		if err != nil {
			return err
		}
	}
	if _, err := tx.Exec(ctx, `SELECT pg_advisory_xact_lock(hashtextextended($1,11))`, deviceID); err != nil {
		return err
	}
	_, err := tx.Exec(ctx, `SELECT device_id FROM device_twin WHERE device_id=$1::uuid FOR UPDATE`, deviceID)
	return err
}

func (s *Service) checkBLETransfer(ctx context.Context, tx pgx.Tx, d Device, target claimRecord, sourceID string) error {
	source := claimRecord{TenantID: d.TenantID, UserID: target.UserID}
	err := tx.QueryRow(ctx, `SELECT household_id::text,subject_id::text FROM device_binding WHERE id=$1::uuid AND device_id=$2::uuid AND tenant_id=$3::uuid AND unbound_at IS NULL AND generation=$4 FOR UPDATE`, sourceID, d.ID, d.TenantID, d.Generation).Scan(&source.HouseholdID, &source.SubjectID)
	if errors.Is(err, pgx.ErrNoRows) {
		return fail(409, "BINDING_CHANGED", "设备归属已变化，请刷新后重新选择")
	}
	if err != nil {
		return err
	}
	if err = claimPermission(ctx, tx, source); err != nil {
		return err
	}
	if source.SubjectID == target.SubjectID {
		return fail(400, "ELDER_UNCHANGED", "请选择另一位使用老人")
	}
	if err = s.expireClaims(ctx, tx, d.ID); err != nil {
		return err
	}
	var busy bool
	err = tx.QueryRow(ctx, `SELECT
		EXISTS(SELECT 1 FROM call_session WHERE device_id=$1::uuid AND call_state IN ('PREPARING','STARTING','TALKING','STOPPING')) OR
		EXISTS(SELECT 1 FROM conversation WHERE device_id=$1::uuid AND status NOT IN ('COMPLETED','FAILED','EXPIRED')) OR
		EXISTS(SELECT 1 FROM device_command WHERE device_id=$1::uuid AND status IN ('QUEUED','DELIVERED','ACKNOWLEDGED') AND expires_at>now()) OR
		EXISTS(SELECT 1 FROM firmware_assignment WHERE device_id=$1::uuid AND status IN ('PENDING','ASSIGNED','COMMAND_QUEUED','DOWNLOADING','INSTALLING')) OR
		EXISTS(SELECT 1 FROM fleet_ota WHERE device_id=$1::uuid AND status IN ('pending','accepted')) OR
		EXISTS(SELECT 1 FROM device_binding_claim WHERE device_id=$1::uuid AND status='PENDING') OR
		EXISTS(SELECT 1 FROM device_account_binding WHERE device_id=$1::uuid AND released_at IS NULL)`, d.ID).Scan(&busy)
	if err != nil {
		return err
	}
	if busy {
		return fail(409, "DEVICE_BUSY", "设备有通话、命令、升级或待确认操作，请完成后重试")
	}
	return nil
}

// Only commitBLEBinding, after DEVREQ1 device authentication, can reach this.
// The old assignment stays active while a token waits for the physical tap.
func (s *Service) commitBLETransfer(ctx context.Context, tx pgx.Tx, d Device, c bleClaim, requestID, token string) (map[string]any, error) {
	if err := s.checkBLETransfer(ctx, tx, d, c.claimRecord, c.BindingID); err != nil {
		return nil, err
	}
	sourceID := c.BindingID
	if _, err := tx.Exec(ctx, `UPDATE device_binding SET unbound_at=now(),unbound_by=$2::uuid,reason='ble_physical_transfer' WHERE id=$1::uuid`, sourceID, c.UserID); err != nil {
		return nil, err
	}
	// Closing the old binding advances the generation. The new claim must be
	// fenced against that value, and its receipt must survive response retries.
	d, err := readDevice(ctx, tx, d.ID, true)
	if err != nil {
		return nil, err
	}
	c.Generation = d.Generation
	if _, err = tx.Exec(ctx, `UPDATE device_ble_binding SET expected_generation=$2 WHERE id=$1::uuid`, c.ID, d.Generation); err != nil {
		return nil, err
	}
	result, err := s.commitBLESubject(ctx, tx, d, c, requestID, token)
	if err != nil {
		return nil, err
	}
	if err = s.auditEvent(ctx, tx, d, "device", d.PublicID, "device.binding.ble_transfer", requestID, map[string]any{"previous_binding_id": sourceID, "binding_generation": d.Generation + 1}); err != nil {
		return nil, err
	}
	return result, tx.Commit(ctx)
}