optirs-tpu 0.3.1

//! TPU Pod Coordination and Management
//!
//! This module provides coordination and management functionality for TPU pods,
//! including distributed computation, synchronization, fault tolerance, and
//! load balancing across multiple TPU devices.

use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use std::sync::{Arc, Mutex};
use std::time::{Duration, Instant};
use thiserror::Error;

/// TPU Pod Coordinator manages multiple TPU devices and orchestrates distributed computation
#[derive(Debug)]
pub struct PodCoordinator {
    /// Configuration for the pod
    config: PodConfig,

    /// List of TPU devices in the pod
    devices: Vec<TpuDevice>,

    /// Current state of the pod
    state: Arc<Mutex<PodState>>,

    /// Communication channels between devices
    communication_channels: HashMap<TpuDeviceId, CommunicationChannel>,

    /// Load balancer for distributing work
    load_balancer: LoadBalancer,

    /// Fault tolerance manager
    fault_manager: FaultToleranceManager,

    /// Performance monitor
    performance_monitor: PerformanceMonitor,
}

/// Configuration for TPU pod coordination
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct PodConfig {
    /// Number of TPU devices in the pod
    pub num_devices: usize,

    /// Topology type (e.g., mesh, torus, ring)
    pub topology: TopologyType,

    /// Coordination strategy
    pub coordination_strategy: CoordinationStrategy,

    /// Synchronization mode
    pub sync_mode: SynchronizationMode,

    /// Fault tolerance configuration
    pub fault_tolerance: FaultToleranceConfig,

    /// Performance monitoring settings
    pub monitoring: MonitoringConfig,

    /// Load balancing strategy
    pub load_balancing: LoadBalancingStrategy,

    /// Communication timeout
    pub communication_timeout: Duration,

    /// Maximum retry attempts for failed operations
    pub max_retry_attempts: usize,
}

/// TPU device representation
#[derive(Debug, Clone)]
pub struct TpuDevice {
    /// Unique device identifier
    pub id: TpuDeviceId,

    /// Device capabilities
    pub capabilities: DeviceCapabilities,

    /// Current device state
    pub state: DeviceState,

    /// Current workload
    pub workload: Option<WorkloadInfo>,

    /// Performance metrics
    pub metrics: DeviceMetrics,

    /// Last heartbeat timestamp
    pub last_heartbeat: Instant,
}

/// Unique identifier for TPU devices
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub struct TpuDeviceId(pub u32);

/// TPU device capabilities
#[derive(Debug, Clone)]
pub struct DeviceCapabilities {
    /// Compute cores available
    pub compute_cores: u32,

    /// Memory capacity in GB
    pub memory_gb: f64,

    /// Peak compute performance (TOPS)
    pub peak_tops: f64,

    /// Memory bandwidth (GB/s)
    pub memory_bandwidth_gb_s: f64,

    /// Supported data types
    pub supported_dtypes: Vec<DataType>,

    /// Maximum matrix multiplication dimensions
    pub max_matmul_dims: (usize, usize, usize),
}

/// Device state enumeration
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum DeviceState {
    /// Device is idle and available
    Idle,
    /// Device is actively computing
    Computing,
    /// Device is waiting for synchronization
    Waiting,
    /// Device is communicating with other devices
    Communicating,
    /// Device has encountered an error
    Error(String),
    /// Device is offline or unavailable
    Offline,
}

/// Workload information for a device
#[derive(Debug, Clone)]
pub struct WorkloadInfo {
    /// Workload identifier
    pub id: String,

    /// Type of computation
    pub computation_type: ComputationType,

    /// Estimated completion time
    pub estimated_completion: Duration,

    /// Resource utilization
    pub resource_utilization: ResourceUtilization,

    /// Priority level
    pub priority: WorkloadPriority,
}

/// Pod state tracking
#[derive(Debug, Clone)]
pub struct PodState {
    /// Overall pod status
    pub status: PodStatus,

    /// Number of active devices
    pub active_devices: usize,

    /// Current computation phase
    pub computation_phase: ComputationPhase,

    /// Synchronization barriers active
    pub active_barriers: Vec<BarrierInfo>,

    /// Global step counter
    pub global_step: u64,

    /// Last coordination timestamp
    pub last_coordination: Instant,
}

/// Pod status enumeration
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum PodStatus {
    Initializing,
    Ready,
    Computing,
    Synchronizing,
    Error(String),
    Shutdown,
}

/// Computation phases in distributed training
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum ComputationPhase {
    Forward,
    Backward,
    ParameterUpdate,
    AllReduce,
    Checkpoint,
}

/// Communication channel between devices
#[derive(Debug)]
pub struct CommunicationChannel {
    /// Source device
    pub source: TpuDeviceId,

    /// Target device
    pub target: TpuDeviceId,

    /// Channel bandwidth (GB/s)
    pub bandwidth_gb_s: f64,

    /// Current latency (microseconds)
    pub latency_us: f64,

    /// Message queue
    pub message_queue: Arc<Mutex<Vec<Message>>>,

    /// Channel state
    pub state: ChannelState,
}

/// Message for inter-device communication
#[derive(Debug, Clone)]
pub struct Message {
    /// Message identifier
    pub id: String,

    /// Message type
    pub message_type: MessageType,

    /// Payload data
    pub payload: Vec<u8>,

    /// Timestamp
    pub timestamp: Instant,

    /// Priority
    pub priority: MessagePriority,
}

/// Load balancer for distributing work across devices
#[derive(Debug)]
pub struct LoadBalancer {
    /// Balancing strategy
    strategy: LoadBalancingStrategy,

    /// Device utilization tracking
    utilization_tracker: HashMap<TpuDeviceId, f64>,

    /// Work queue
    work_queue: Arc<Mutex<Vec<WorkItem>>>,
}

/// Fault tolerance manager
#[derive(Debug)]
pub struct FaultToleranceManager {
    /// Configuration
    config: FaultToleranceConfig,

    /// Failed device tracking
    failed_devices: HashMap<TpuDeviceId, FailureInfo>,

    /// Recovery strategies
    recovery_strategies: Vec<RecoveryStrategy>,

    /// Checkpointing system
    checkpoint_manager: CheckpointManager,
}

/// Performance monitoring system
#[derive(Debug)]
pub struct PerformanceMonitor {
    /// Configuration
    config: MonitoringConfig,

    /// Metrics collection
    metrics_collector: MetricsCollector,

    /// Performance history
    performance_history: Vec<PerformanceSnapshot>,

    /// Alerting system
    alerting: AlertingSystem,
}

// Enumerations and supporting types

#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum TopologyType {
    Mesh,
    Torus,
    Ring,
    Tree,
    Custom,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum CoordinationStrategy {
    Centralized,
    Decentralized,
    Hierarchical,
    Adaptive,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum SynchronizationMode {
    Synchronous,
    Asynchronous,
    BulkSynchronous,
    EventDriven,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum LoadBalancingStrategy {
    RoundRobin,
    LeastLoaded,
    WeightedRoundRobin,
    Performance,
    Adaptive,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum DataType {
    Float32,
    Float16,
    BFloat16,
    Int32,
    Int16,
    Int8,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ComputationType {
    MatrixMultiplication,
    Convolution,
    Attention,
    Embedding,
    Normalization,
    Activation,
    Reduction,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum WorkloadPriority {
    Low,
    Medium,
    High,
    Critical,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ChannelState {
    Active,
    Congested,
    Failed,
    Maintenance,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum MessageType {
    Data,
    Control,
    Synchronization,
    Heartbeat,
    Error,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum MessagePriority {
    Low,
    Normal,
    High,
    Urgent,
}

// Configuration structures

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct FaultToleranceConfig {
    pub enable_checkpointing: bool,
    pub checkpoint_interval: Duration,
    pub max_failures: usize,
    pub recovery_timeout: Duration,
    pub enable_redundancy: bool,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct MonitoringConfig {
    pub collection_interval: Duration,
    pub metrics_retention: Duration,
    pub enable_profiling: bool,
    pub alert_thresholds: HashMap<String, f64>,
}

// Supporting structures

#[derive(Debug, Clone)]
pub struct DeviceMetrics {
    pub utilization: f64,
    pub memory_usage: f64,
    pub temperature: f64,
    pub power_consumption: f64,
    pub throughput_tops: f64,
    pub error_count: u64,
}

#[derive(Debug, Clone)]
pub struct ResourceUtilization {
    pub compute: f64,
    pub memory: f64,
    pub bandwidth: f64,
}

#[derive(Debug, Clone)]
pub struct BarrierInfo {
    pub id: String,
    pub waiting_devices: Vec<TpuDeviceId>,
    pub completed_devices: Vec<TpuDeviceId>,
    pub timeout: Duration,
}

#[derive(Debug, Clone)]
pub struct WorkItem {
    pub id: String,
    pub computation: ComputationType,
    pub data_size: usize,
    pub priority: WorkloadPriority,
    pub target_device: Option<TpuDeviceId>,
}

#[derive(Debug, Clone)]
pub struct FailureInfo {
    pub failure_type: FailureType,
    pub timestamp: Instant,
    pub error_message: String,
    pub recovery_attempts: usize,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum FailureType {
    Hardware,
    Software,
    Communication,
    Timeout,
    Memory,
}

#[derive(Debug)]
pub struct RecoveryStrategy {
    pub strategy_type: RecoveryStrategyType,
    pub applicability: Vec<FailureType>,
    pub cost: f64,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum RecoveryStrategyType {
    Restart,
    Reassign,
    Redundancy,
    Checkpointing,
}

#[derive(Debug)]
pub struct CheckpointManager {
    pub checkpoint_interval: Duration,
    pub checkpoint_storage: String,
    pub compression_enabled: bool,
}

#[derive(Debug)]
pub struct MetricsCollector {
    pub collection_interval: Duration,
    pub metrics_buffer: Arc<Mutex<Vec<MetricData>>>,
}

#[derive(Debug, Clone)]
pub struct MetricData {
    pub device_id: TpuDeviceId,
    pub timestamp: Instant,
    pub metric_type: MetricType,
    pub value: f64,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum MetricType {
    Utilization,
    Throughput,
    Latency,
    Memory,
    Power,
    Temperature,
    ErrorRate,
}

#[derive(Debug, Clone)]
pub struct PerformanceSnapshot {
    pub timestamp: Instant,
    pub overall_utilization: f64,
    pub throughput: f64,
    pub active_devices: usize,
    pub bottlenecks: Vec<BottleneckInfo>,
}

#[derive(Debug, Clone)]
pub struct BottleneckInfo {
    pub bottleneck_type: BottleneckType,
    pub affected_devices: Vec<TpuDeviceId>,
    pub severity: f64,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum BottleneckType {
    Compute,
    Memory,
    Communication,
    Synchronization,
}

#[derive(Debug)]
pub struct AlertingSystem {
    pub thresholds: HashMap<MetricType, f64>,
    pub alert_handlers: Vec<AlertHandler>,
}

#[derive(Debug)]
pub struct AlertHandler {
    pub handler_type: AlertHandlerType,
    pub severity_threshold: AlertSeverity,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum AlertHandlerType {
    Log,
    Email,
    Webhook,
    Sms,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum AlertSeverity {
    Info,
    Warning,
    Error,
    Critical,
}

/// Errors that can occur during pod coordination
#[derive(Debug, Error)]
pub enum CoordinationError {
    #[error("Device not found: {device_id:?}")]
    DeviceNotFound { device_id: TpuDeviceId },

    #[error("Communication timeout with device: {device_id:?}")]
    CommunicationTimeout { device_id: TpuDeviceId },

    #[error("Synchronization failed: {reason}")]
    SynchronizationFailed { reason: String },

    #[error("Load balancing error: {reason}")]
    LoadBalancingError { reason: String },

    #[error("Fault tolerance error: {reason}")]
    FaultToleranceError { reason: String },

    #[error("Configuration error: {reason}")]
    ConfigurationError { reason: String },

    #[error("Resource exhaustion: {resource}")]
    ResourceExhaustion { resource: String },

    #[error("Pod initialization failed: {reason}")]
    InitializationFailed { reason: String },
}

impl PodCoordinator {
    /// Create a new pod coordinator with the given configuration
    pub fn new(config: PodConfig) -> Result<Self, CoordinationError> {
        let devices = Self::initialize_devices(&config)?;
        let state = Arc::new(Mutex::new(PodState {
            status: PodStatus::Initializing,
            active_devices: devices.len(),
            computation_phase: ComputationPhase::Forward,
            active_barriers: Vec::new(),
            global_step: 0,
            last_coordination: Instant::now(),
        }));

        let communication_channels = Self::setup_communication_channels(&devices, &config)?;
        let load_balancer = LoadBalancer::new(config.load_balancing);
        let fault_manager = FaultToleranceManager::new(config.fault_tolerance.clone());
        let performance_monitor = PerformanceMonitor::new(config.monitoring.clone());

        Ok(Self {
            config,
            devices,
            state,
            communication_channels,
            load_balancer,
            fault_manager,
            performance_monitor,
        })
    }

    /// Initialize TPU devices based on configuration
    fn initialize_devices(config: &PodConfig) -> Result<Vec<TpuDevice>, CoordinationError> {
        let mut devices = Vec::new();

        for i in 0..config.num_devices {
            let device = TpuDevice {
                id: TpuDeviceId(i as u32),
                capabilities: DeviceCapabilities {
                    compute_cores: 2,
                    memory_gb: 32.0,
                    peak_tops: 275.0,
                    memory_bandwidth_gb_s: 1600.0,
                    supported_dtypes: vec![
                        DataType::Float32,
                        DataType::Float16,
                        DataType::BFloat16,
                    ],
                    max_matmul_dims: (8192, 8192, 8192),
                },
                state: DeviceState::Idle,
                workload: None,
                metrics: DeviceMetrics {
                    utilization: 0.0,
                    memory_usage: 0.0,
                    temperature: 25.0,
                    power_consumption: 100.0,
                    throughput_tops: 0.0,
                    error_count: 0,
                },
                last_heartbeat: Instant::now(),
            };

            devices.push(device);
        }

        Ok(devices)
    }

    /// Setup communication channels between devices
    fn setup_communication_channels(
        devices: &[TpuDevice],
        _config: &PodConfig,
    ) -> Result<HashMap<TpuDeviceId, CommunicationChannel>, CoordinationError> {
        let mut channels = HashMap::new();

        for device in devices {
            for other_device in devices {
                if device.id != other_device.id {
                    let channel = CommunicationChannel {
                        source: device.id,
                        target: other_device.id,
                        bandwidth_gb_s: 300.0, // TPU interconnect bandwidth
                        latency_us: 2.0,       // Low latency interconnect
                        message_queue: Arc::new(Mutex::new(Vec::new())),
                        state: ChannelState::Active,
                    };

                    channels.insert(device.id, channel);
                }
            }
        }

        Ok(channels)
    }

    /// Start the pod coordination
    pub fn start(&mut self) -> Result<(), CoordinationError> {
        {
            let mut state = self.state.lock().expect("lock poisoned");
            state.status = PodStatus::Ready;
            state.last_coordination = Instant::now();
        }

        // Start monitoring and coordination loops
        self.performance_monitor.start_monitoring()?;
        self.fault_manager.start_fault_detection()?;

        Ok(())
    }

    /// Submit a computation workload to the pod
    pub fn submit_workload(&mut self, workload: WorkloadInfo) -> Result<(), CoordinationError> {
        let target_device = self.load_balancer.select_device(&self.devices, &workload)?;

        if let Some(device) = self.devices.iter_mut().find(|d| d.id == target_device) {
            device.workload = Some(workload);
            device.state = DeviceState::Computing;
        }

        Ok(())
    }

    /// Synchronize all devices at a barrier
    pub fn synchronize_devices(&mut self, barrier_id: String) -> Result<(), CoordinationError> {
        let mut state = self.state.lock().expect("lock poisoned");

        let barrier = BarrierInfo {
            id: barrier_id,
            waiting_devices: self.devices.iter().map(|d| d.id).collect(),
            completed_devices: Vec::new(),
            timeout: self.config.communication_timeout,
        };

        state.active_barriers.push(barrier);
        state.status = PodStatus::Synchronizing;

        // In a real implementation, this would wait for all devices to reach the barrier
        // For now, we'll simulate completion
        std::thread::sleep(Duration::from_millis(10));

        state.active_barriers.clear();
        state.status = PodStatus::Ready;

        Ok(())
    }

    /// Get current pod status
    pub fn get_status(&self) -> PodState {
        self.state.lock().expect("lock poisoned").clone()
    }

    /// Get device metrics
    pub fn get_device_metrics(&self, device_id: TpuDeviceId) -> Option<DeviceMetrics> {
        self.devices
            .iter()
            .find(|d| d.id == device_id)
            .map(|d| d.metrics.clone())
    }

    /// Shutdown the pod
    pub fn shutdown(&mut self) -> Result<(), CoordinationError> {
        {
            let mut state = self.state.lock().expect("lock poisoned");
            state.status = PodStatus::Shutdown;
        }

        // Stop all devices and cleanup
        for device in &mut self.devices {
            device.state = DeviceState::Offline;
        }

        Ok(())
    }
}

impl LoadBalancer {
    fn new(strategy: LoadBalancingStrategy) -> Self {
        Self {
            strategy,
            utilization_tracker: HashMap::new(),
            work_queue: Arc::new(Mutex::new(Vec::new())),
        }
    }

    fn select_device(
        &mut self,
        devices: &[TpuDevice],
        _workload: &WorkloadInfo,
    ) -> Result<TpuDeviceId, CoordinationError> {
        match self.strategy {
            LoadBalancingStrategy::LeastLoaded => {
                let device = devices
                    .iter()
                    .filter(|d| matches!(d.state, DeviceState::Idle))
                    .min_by(|a, b| {
                        a.metrics
                            .utilization
                            .partial_cmp(&b.metrics.utilization)
                            .expect("unwrap failed")
                    });

                device
                    .map(|d| d.id)
                    .ok_or_else(|| CoordinationError::ResourceExhaustion {
                        resource: "Available devices".to_string(),
                    })
            }
            LoadBalancingStrategy::RoundRobin => {
                // Simple round-robin implementation
                let idle_devices: Vec<_> = devices
                    .iter()
                    .filter(|d| matches!(d.state, DeviceState::Idle))
                    .collect();

                if idle_devices.is_empty() {
                    return Err(CoordinationError::ResourceExhaustion {
                        resource: "Available devices".to_string(),
                    });
                }

                Ok(idle_devices[0].id)
            }
            _ => {
                // Default to first available device
                devices
                    .iter()
                    .find(|d| matches!(d.state, DeviceState::Idle))
                    .map(|d| d.id)
                    .ok_or_else(|| CoordinationError::ResourceExhaustion {
                        resource: "Available devices".to_string(),
                    })
            }
        }
    }
}

impl FaultToleranceManager {
    fn new(config: FaultToleranceConfig) -> Self {
        Self {
            config,
            failed_devices: HashMap::new(),
            recovery_strategies: Vec::new(),
            checkpoint_manager: CheckpointManager {
                checkpoint_interval: Duration::from_secs(300),
                checkpoint_storage: "/tmp/checkpoints".to_string(),
                compression_enabled: true,
            },
        }
    }

    fn start_fault_detection(&mut self) -> Result<(), CoordinationError> {
        // In a real implementation, this would start background threads
        // for fault detection and recovery
        Ok(())
    }
}

impl PerformanceMonitor {
    fn new(config: MonitoringConfig) -> Self {
        Self {
            config,
            metrics_collector: MetricsCollector {
                collection_interval: Duration::from_secs(1),
                metrics_buffer: Arc::new(Mutex::new(Vec::new())),
            },
            performance_history: Vec::new(),
            alerting: AlertingSystem {
                thresholds: HashMap::new(),
                alert_handlers: Vec::new(),
            },
        }
    }

    fn start_monitoring(&mut self) -> Result<(), CoordinationError> {
        // In a real implementation, this would start background monitoring
        Ok(())
    }
}

impl Default for PodConfig {
    fn default() -> Self {
        Self {
            num_devices: 8,
            topology: TopologyType::Mesh,
            coordination_strategy: CoordinationStrategy::Centralized,
            sync_mode: SynchronizationMode::Synchronous,
            fault_tolerance: FaultToleranceConfig {
                enable_checkpointing: true,
                checkpoint_interval: Duration::from_secs(300),
                max_failures: 3,
                recovery_timeout: Duration::from_secs(60),
                enable_redundancy: false,
            },
            monitoring: MonitoringConfig {
                collection_interval: Duration::from_secs(1),
                metrics_retention: Duration::from_secs(3600),
                enable_profiling: true,
                alert_thresholds: HashMap::new(),
            },
            load_balancing: LoadBalancingStrategy::LeastLoaded,
            communication_timeout: Duration::from_secs(30),
            max_retry_attempts: 3,
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_pod_coordinator_creation() {
        let config = PodConfig::default();
        let coordinator = PodCoordinator::new(config);
        assert!(coordinator.is_ok());
    }

    #[test]
    fn test_device_initialization() {
        let config = PodConfig {
            num_devices: 4,
            ..Default::default()
        };

        let devices = PodCoordinator::initialize_devices(&config).expect("unwrap failed");
        assert_eq!(devices.len(), 4);

        for (i, device) in devices.iter().enumerate() {
            assert_eq!(device.id.0, i as u32);
            assert!(matches!(device.state, DeviceState::Idle));
        }
    }

    #[test]
    fn test_load_balancer() {
        let mut load_balancer = LoadBalancer::new(LoadBalancingStrategy::LeastLoaded);

        let devices = vec![TpuDevice {
            id: TpuDeviceId(0),
            capabilities: DeviceCapabilities {
                compute_cores: 2,
                memory_gb: 32.0,
                peak_tops: 275.0,
                memory_bandwidth_gb_s: 1600.0,
                supported_dtypes: vec![DataType::Float32],
                max_matmul_dims: (8192, 8192, 8192),
            },
            state: DeviceState::Idle,
            workload: None,
            metrics: DeviceMetrics {
                utilization: 0.5,
                memory_usage: 0.3,
                temperature: 25.0,
                power_consumption: 100.0,
                throughput_tops: 100.0,
                error_count: 0,
            },
            last_heartbeat: Instant::now(),
        }];

        let workload = WorkloadInfo {
            id: "test_workload".to_string(),
            computation_type: ComputationType::MatrixMultiplication,
            estimated_completion: Duration::from_secs(10),
            resource_utilization: ResourceUtilization {
                compute: 0.8,
                memory: 0.6,
                bandwidth: 0.4,
            },
            priority: WorkloadPriority::Medium,
        };

        let selected = load_balancer.select_device(&devices, &workload);
        assert!(selected.is_ok());
        assert_eq!(selected.expect("unwrap failed"), TpuDeviceId(0));
    }
}