package scheduler

import (
	"log"
	"strings"
	"sync"
	"time"

	"crypto-miner-server/internal/db"
	"crypto-miner-server/internal/models"
)

// CommandSender pushes a remote command to a connected agent.
type CommandSender interface {
	SendAgentCommand(agentID, action string, args map[string]interface{}) error
	ConnectedAgentIDs() []string
}

// FleetScheduler runs interval and cron fleet tasks against connected agents.
type FleetScheduler struct {
	db   *db.Database
	send CommandSender
	stop chan struct{}
	wg   sync.WaitGroup

	cronMu       sync.Mutex
	lastCronRuns map[string]string // taskID -> "2006-01-02 15:04"
}

func New(db *db.Database, send CommandSender) *FleetScheduler {
	return &FleetScheduler{
		db:           db,
		send:         send,
		stop:         make(chan struct{}),
		lastCronRuns: make(map[string]string),
	}
}

func (s *FleetScheduler) Start() {
	s.wg.Add(1)
	go s.loop()
}

func (s *FleetScheduler) Stop() {
	close(s.stop)
	s.wg.Wait()
}

func (s *FleetScheduler) loop() {
	defer s.wg.Done()
	ticker := time.NewTicker(1 * time.Minute)
	defer ticker.Stop()
	for {
		select {
		case <-s.stop:
			return
		case <-ticker.C:
			s.tickInterval()
			s.tickCron()
		}
	}
}

// RunConnectTasks executes tasks matching on_connect or on_reconnect for one agent.
func (s *FleetScheduler) RunConnectTasks(agentID string, trigger string) {
	tasks, err := s.db.ListFleetTasks()
	if err != nil {
		log.Printf("[scheduler] list tasks: %v", err)
		return
	}
	for _, t := range tasks {
		if !t.Enabled || t.Trigger != trigger {
			continue
		}
		s.dispatchTask(agentID, t)
	}
}

func (s *FleetScheduler) tickInterval() {
	tasks, err := s.db.ListFleetTasks()
	if err != nil {
		return
	}
	agentIDs := s.send.ConnectedAgentIDs()
	for _, t := range tasks {
		if !t.Enabled || t.Trigger != "interval_hours" || t.IntervalHours <= 0 {
			continue
		}
		interval := time.Duration(t.IntervalHours * float64(time.Hour))
		for _, agentID := range agentIDs {
			last, ok := s.db.LastFleetTaskRun(agentID, t.ID)
			if ok && time.Since(last) < interval {
				continue
			}
			s.dispatchTask(agentID, t)
		}
	}
}

func (s *FleetScheduler) tickCron() {
	now := time.Now()
	slot := now.Format("15:04")
	daySlot := now.Format("2006-01-02") + " " + slot

	tasks, err := s.db.ListFleetTasks()
	if err != nil {
		return
	}
	agentIDs := s.send.ConnectedAgentIDs()
	for _, t := range tasks {
		if !t.Enabled || t.Trigger != "cron" || strings.TrimSpace(t.CronTime) == "" {
			continue
		}
		cronTime := strings.TrimSpace(t.CronTime)
		if cronTime != slot {
			continue
		}
		s.cronMu.Lock()
		if s.lastCronRuns[t.ID] == daySlot {
			s.cronMu.Unlock()
			continue
		}
		s.lastCronRuns[t.ID] = daySlot
		s.cronMu.Unlock()
		for _, agentID := range agentIDs {
			s.dispatchTask(agentID, t)
		}
	}
}

func (s *FleetScheduler) dispatchTask(agentID string, t *models.FleetTask) {
	args := map[string]interface{}{}
	if t.Command != "" {
		args["command"] = t.Command
	}
	if err := s.send.SendAgentCommand(agentID, t.Action, args); err != nil {
		log.Printf("[scheduler] task %s → %s: %v", t.Name, agentID, err)
		return
	}
	_ = s.db.RecordFleetTaskRun(agentID, t.ID)
	log.Printf("[scheduler] dispatched task %q (%s) → agent %s", t.Name, t.Action, agentID)
}