sequenceDiagram
    participant User as Admin/Operator
    participant API as AppSync
    participant AR as action-resolver λ
    participant SQS1 as action-trigger-sqs
    participant AT as action-trigger λ
    participant RDS as RDS PostgreSQL
    participant SNS1 as command-sns
    participant SQS2 as apple-process-action-sqs
    participant OEM as apple-process-action λ
    participant CACHE as Command Cache
    participant APIGW as API Gateway
    participant APNS as Apple APNS
    participant Device as iOS Device
    participant SNS2 as checkin-sns
    participant SQS3 as checkin-handler-sqs
    participant CK as checkin-handler λ

    rect rgb(240, 248, 255)
        Note over AR,AT: BE Layer — Step 1-2
        User->>API: mutation assignAction(deviceId, actionId, messageTemplateId?)
        API->>AR: resolve
        AR->>RDS: SELECT device, action (validate)
        opt messageTemplateId set
            AR->>RDS: SELECT content, is_active FROM message_templates
            AR->>AR: payload.messageContent = template.content (plain, no rendering)
        end
        AR->>RDS: INSERT batch_actions (status=IN_PROGRESS) + batch_device_actions (status=PENDING)
        AR->>SQS1: enqueue {batchId, deviceId, actionId, payload}
        AR-->>API: return { executionId, batchId, status: PENDING }

        SQS1->>AT: trigger
        AT->>RDS: INSERT action_executions (ACTION_PENDING, command_uuid)
        AT->>RDS: UPDATE devices SET assigned_action_id
        AT->>SNS1: publish {command_uuid, device_udid, push_token, push_magic, request_type, payload}
        AT->>RDS: UPDATE batch_device_actions SET status=SUCCESS (dispatch OK)
        Note right of AT: Nếu publish fail / device invalid → batch_device_actions.status=FAILED + error_code
        AT->>RDS: UPDATE batch_actions.status=COMPLETED (khi tất cả rows done)
    end

    rect rgb(255, 248, 240)
        Note over OEM,OEM: OEM Layer — Step 3-5
        SNS1->>SQS2: fan-out
        SQS2->>OEM: trigger (SQS)
        OEM->>CACHE: PUT command (key=device_udid)
        OEM->>APIGW: POST /apns/{token}
        APIGW->>APNS: proxy → silent push {"mdm":"PushMagic"}
        APNS-->>Device: wake up

        Device->>APIGW: PUT /mdm (Status=Idle, UDID)
        APIGW->>OEM: invoke (API GW trigger)
        OEM->>CACHE: GET + DELETE command (key=device_udid)
        OEM-->>Device: 200 {CommandUUID, Command: DeviceLock}

        Device->>Device: execute DeviceLock

        Device->>APIGW: PUT /mdm (Status=Acknowledged, CommandUUID)
        APIGW->>OEM: trigger
        OEM->>SNS2: publish {event: ACTION_COMPLETED, command_uuid, udid}
        OEM-->>Device: 200 (empty body)
    end

    rect rgb(240, 255, 240)
        Note over CK: BE Layer — Step 6
        SNS2->>SQS3: fan-out
        SQS3->>CK: trigger
        CK->>RDS: SELECT action_executions WHERE command_uuid=...
        CK->>RDS: UPDATE action_executions SET status=ACTION_COMPLETED
        CK->>RDS: UPDATE devices SET current_policy_id, assigned_action_id=NULL
        CK->>RDS: INSERT milestones
        CK->>API: AppSync subscription: deviceStateChanged
        Note right of CK: KHÔNG đụng batch_actions/batch_device_actions (đã finalize ở action-trigger)
    end

    API-->>User: subscription update: device locked ✓

sequenceDiagram
    participant OEM as apple-process-action λ
    participant CACHE as Command Cache
    participant APNS as Apple APNS
    participant Device as iOS Device
    participant TH as timeout-handler λ
    participant RDS as RDS PostgreSQL

    OEM->>CACHE: PUT command (TTL=60s)
    OEM->>APNS: silent push
    APNS-->>Device: wake up (device OFFLINE)

    Note over CACHE: TTL expires → command auto-deleted
    Note over TH: EventBridge scheduled rule (every 30s)

    TH->>RDS: SELECT action_executions WHERE status='ACTION_PENDING' AND created_at < NOW() - INTERVAL '60s'
    TH->>RDS: UPDATE action_executions SET status='ACTION_FAILED', ext_fields.failed_reason='device_timeout'
    TH->>RDS: UPDATE devices SET assigned_action_id=NULL

    Note over RDS: Device state giữ nguyên — chỉ clear assigned_action_id

sequenceDiagram
    participant OEM as apple-process-action λ
    participant APNS as Apple APNS
    participant SNS2 as checkin-sns
    participant CK as checkin-handler λ
    participant RDS as RDS PostgreSQL

    OEM->>APNS: silent push
    APNS-->>OEM: 400 BadDeviceToken

    OEM->>SNS2: publish {event: ACTION_FAILED, command_uuid, reason: apns_bad_token}
    SNS2->>CK: via SQS
    CK->>RDS: UPDATE action_executions SET status='ACTION_FAILED'
    CK->>RDS: UPDATE devices SET assigned_action_id=NULL

sequenceDiagram
    participant SQS as action-trigger-sqs
    participant AT as action-trigger λ
    participant DLQ as DLQ
    participant DH as dlq-handler λ
    participant RDS as RDS PostgreSQL

    SQS->>AT: attempt 1 (exception)
    SQS->>AT: attempt 2 (exception)
    SQS->>AT: attempt 3 (exception)
    SQS->>DLQ: maxReceiveCount=3 reached

    DLQ->>DH: trigger
    alt Recoverable
        DH->>SQS: re-enqueue with delay
    else Non-recoverable
        DH->>RDS: UPDATE action_executions SET status='ACTION_FAILED'
        DH->>RDS: UPDATE devices SET assigned_action_id=NULL
        Note over DH: CloudWatch Alarm → alert ops
    end

sequenceDiagram
    participant User as Admin
    participant API as AppSync
    participant AR as action-resolver λ
    participant SQS1 as action-trigger-sqs
    participant RDS as RDS PostgreSQL

    User->>API: mutation assignBulkAction(deviceIds[], actionId)
    API->>AR: resolve

    loop for each deviceId
        AR->>RDS: SELECT device (validate busy + transition)
        alt Valid
            AR->>SQS1: enqueue {deviceId, actionId}
        else Invalid
            AR->>AR: collect error
        end
    end
    AR-->>API: { valid: [...executionIds], failed: [...errors] }

    Note over SQS1: Mỗi message → independent pipeline<br/>Song song, không có bulk transaction