package scheduler

import (
	"context"
	"log/slog"
	"time"

	agentv1 "github.com/containarr/server/internal/proto/agentv1"
	"github.com/google/uuid"
)

// DuePolicy is a minimal view of an auto-update policy returned by the store.
type DuePolicy struct {
	AgentID     string
	ContainerID string
}

// StoreInterface defines the minimal store methods used by the scheduler.
// Implementations must convert their internal policy type to DuePolicy when
// implementing ListDueAutoUpdatePolicies, or use StoreAdapter provided below.
type StoreInterface interface {
	ListDueAutoUpdatePolicies(now time.Time) ([]DuePolicy, error)
	UpdateAutoUpdateChecked(agentID, containerID string, at time.Time) error
}

// RegistryInterface defines the minimal registry methods used by the scheduler.
type RegistryInterface interface {
	Send(agentID string, msg *agentv1.ServerMessage) bool
}

// Scheduler sends CheckUpdateCommand to agents every 60 seconds for containers
// with an active and due auto-update policy.
type Scheduler struct {
	store    StoreInterface
	registry RegistryInterface
}

// New creates a new Scheduler.
func New(store StoreInterface, registry RegistryInterface) *Scheduler {
	return &Scheduler{store: store, registry: registry}
}

// Start runs the scheduler loop until ctx is cancelled.
func (s *Scheduler) Start(ctx context.Context) {
	ticker := time.NewTicker(60 * time.Second)
	defer ticker.Stop()

	for {
		select {
		case <-ctx.Done():
			slog.Info("scheduler stopped")
			return
		case t := <-ticker.C:
			s.tick(t)
		}
	}
}

func (s *Scheduler) tick(now time.Time) {
	policies, err := s.store.ListDueAutoUpdatePolicies(now)
	if err != nil {
		slog.Error("scheduler: list due policies", "err", err)
		return
	}

	for _, p := range policies {
		cmdID := uuid.NewString()
		msg := &agentv1.ServerMessage{
			Payload: &agentv1.ServerMessage_CheckUpdate{
				CheckUpdate: &agentv1.CheckUpdateCommand{
					CommandId:   cmdID,
					ContainerId: p.ContainerID,
				},
			},
		}
		sent := s.registry.Send(p.AgentID, msg)
		if !sent {
			slog.Debug("scheduler: agent not connected, skipping", "agent_id", p.AgentID, "container_id", p.ContainerID)
			continue
		}
		if err := s.store.UpdateAutoUpdateChecked(p.AgentID, p.ContainerID, now); err != nil {
			slog.Error("scheduler: update last_checked_at", "agent_id", p.AgentID, "container_id", p.ContainerID, "err", err)
		}
		slog.Info("scheduler: sent CheckUpdateCommand", "agent_id", p.AgentID, "container_id", p.ContainerID, "command_id", cmdID)
	}
}