// Package domain contains pure domain models with no external dependencies.
package domain

import "time"

// Worker represents a registered worker in the pool.
type Worker struct {
	// ID is the unique worker identifier (typically pod name).
	ID string `json:"id"`

	// Hostname is the worker's hostname.
	Hostname string `json:"hostname"`

	// Status is the current worker state.
	Status WorkerStatus `json:"status"`

	// CurrentTask is the ID of the task currently being executed.
	CurrentTask string `json:"current_task,omitempty"`

	// Capabilities lists what this worker can do (e.g., "build", "deploy").
	Capabilities []string `json:"capabilities,omitempty"`

	// RegisteredAt is when the worker first joined the pool.
	RegisteredAt time.Time `json:"registered_at"`

	// LastHeartbeat is the most recent heartbeat timestamp.
	LastHeartbeat time.Time `json:"last_heartbeat"`

	// Version is the worker binary version.
	Version string `json:"version,omitempty"`
}

// IsAvailable returns true if the worker can accept new tasks.
func (w *Worker) IsAvailable() bool {
	return w.Status == WorkerStatusIdle
}

// IsHealthy returns true if the worker has a recent heartbeat.
func (w *Worker) IsHealthy(threshold time.Duration) bool {
	return time.Since(w.LastHeartbeat) < threshold
}

// WorkerStatus represents the current state of a worker.
type WorkerStatus string

const (
	WorkerStatusIdle     WorkerStatus = "idle"
	WorkerStatusBusy     WorkerStatus = "busy"
	WorkerStatusDraining WorkerStatus = "draining"
	WorkerStatusOffline  WorkerStatus = "offline"
)

// IsValid returns true if the status is a known valid status.
func (s WorkerStatus) IsValid() bool {
	switch s {
	case WorkerStatusIdle, WorkerStatusBusy, WorkerStatusDraining, WorkerStatusOffline:
		return true
	}
	return false
}

// ValidWorkerStatuses returns all valid worker status values.
func ValidWorkerStatuses() []WorkerStatus {
	return []WorkerStatus{WorkerStatusIdle, WorkerStatusBusy, WorkerStatusDraining, WorkerStatusOffline}
}

// Validate checks that the Worker has required fields for registration.
func (w *Worker) Validate() error {
	if w.ID == "" {
		return ErrWorkerIDRequired
	}
	if w.Hostname == "" {
		return ErrWorkerHostnameRequired
	}
	return nil
}