package services

import (
	"bookhoard/internal/database"
	"context"
	"fmt"
	"log"
	"sync"
	"time"

	"github.com/google/uuid"
	"github.com/jackc/pgx/v5/pgtype"
)

type Scheduler struct {
	worker       *Worker
	db           Database
	timers       map[string]*time.Timer
	mu           sync.RWMutex
	scanSettings map[string]ScanSetting
	ctx          context.Context
	cancel       context.CancelFunc
	wg           sync.WaitGroup
}

type Database interface {
	GetScanSettings(ctx context.Context, id pgtype.UUID) (database.GetScanSettingsRow, error)
	ListLibraries(ctx context.Context) ([]database.ListLibrariesRow, error)
	GetLibraryFolders(ctx context.Context, libraryID pgtype.UUID) ([]database.LibraryFolders, error)
}

type ScanSettingRow struct {
	ScanFrequencyMinutes pgtype.Int4
	AutoScanEnabled      pgtype.Bool
}

type Library struct {
	ID   pgtype.UUID
	Name string
}

type LibraryFolder struct {
	ID         pgtype.UUID
	LibraryID  pgtype.UUID
	FolderPath string
}

type ScanSetting struct {
	UserID    string
	Enabled   bool
	Frequency int
}

func NewScheduler(worker *Worker, db Database) *Scheduler {
	ctx, cancel := context.WithCancel(context.Background())

	return &Scheduler{
		worker:       worker,
		db:           db,
		timers:       make(map[string]*time.Timer),
		scanSettings: make(map[string]ScanSetting),
		ctx:          ctx,
		cancel:       cancel,
	}
}

func (s *Scheduler) Start() {
	s.wg.Add(1)
	go s.runSettingsChecker()
}

func (s *Scheduler) Stop() {
	s.cancel()

	s.mu.Lock()
	for _, timer := range s.timers {
		timer.Stop()
	}
	s.timers = make(map[string]*time.Timer)
	s.mu.Unlock()

	s.wg.Wait()
}

func (s *Scheduler) runSettingsChecker() {
	ticker := time.NewTicker(5 * time.Minute)
	defer ticker.Stop()

	for {
		select {
		case <-ticker.C:
			s.checkAndScheduleScans()
		case <-s.ctx.Done():
			return
		}
	}
}

func (s *Scheduler) checkAndScheduleScans() {
	ctx, cancel := context.WithTimeout(s.ctx, 30*time.Second)
	defer cancel()

	libraries, err := s.db.ListLibraries(ctx)
	if err != nil {
		log.Printf("Error fetching libraries for scan scheduling: %v", err)
		return
	}

	for _, library := range libraries {
		settings, err := s.db.GetScanSettings(ctx, library.ID)
		if err != nil {
			libraryIDStr := fmt.Sprintf("%x", library.ID.Bytes)
			log.Printf("Error getting scan settings for library %s: %v", libraryIDStr, err)
			continue
		}

		if !settings.AutoScanEnabled.Bool || settings.ScanFrequencyMinutes.Int32 < 15 {
			continue
		}

		userID := fmt.Sprintf("%x", library.ID.Bytes)

		s.mu.Lock()
		currentSetting, exists := s.scanSettings[userID]
		scanSetting := ScanSetting{
			UserID:    userID,
			Enabled:   settings.AutoScanEnabled.Bool,
			Frequency: int(settings.ScanFrequencyMinutes.Int32),
		}
		s.scanSettings[userID] = scanSetting
		s.mu.Unlock()

		if !exists || currentSetting.Frequency != scanSetting.Frequency {
			s.scheduleLibraryScan(ctx, library.ID, userID, scanSetting.Frequency)
		}
	}
}

func (s *Scheduler) scheduleLibraryScan(ctx context.Context, libraryID pgtype.UUID, userID string, frequencyMinutes int) {
	userIDStr := fmt.Sprintf("%x", libraryID.Bytes)

	s.mu.Lock()
	defer s.mu.Unlock()

	timerID := userIDStr + "-scan"

	if existingTimer, exists := s.timers[timerID]; exists {
		existingTimer.Stop()
	}

	duration := time.Duration(frequencyMinutes) * time.Minute
	timer := time.AfterFunc(duration, func() {
		s.triggerScheduledScan(ctx, libraryID, userIDStr)

		s.scheduleLibraryScan(ctx, libraryID, userID, frequencyMinutes)
	})

	s.timers[timerID] = timer

	libraryIDStr := fmt.Sprintf("%x", libraryID.Bytes)
	log.Printf("Scheduled scan for library %s every %d minutes", libraryIDStr, frequencyMinutes)
}

func (s *Scheduler) triggerScheduledScan(ctx context.Context, libraryID pgtype.UUID, userID string) {
	libraryIDStr := fmt.Sprintf("%x", libraryID.Bytes)
	log.Printf("Triggering scheduled scan for library %s", libraryIDStr)

	folders, err := s.db.GetLibraryFolders(ctx, libraryID)
	if err != nil {
		log.Printf("Error getting folders for library %s: %v", libraryIDStr, err)
		return
	}

	if len(folders) == 0 {
		log.Printf("No folders configured for library %s, skipping scan", libraryIDStr)
		return
	}

	folderPaths := make([]string, len(folders))
	for i, folder := range folders {
		folderPaths[i] = folder.FolderPath
	}

	job := &Job{
		ID:   uuid.New().String(),
		Type: JobTypeScan,
		Params: map[string]interface{}{
			"library_id": fmt.Sprintf("%x", libraryID.Bytes),
			"folders":    folderPaths,
			"admin_id":   userID,
			"db":         s.db,
		},
		Status:  JobStatusPending,
		Context: ctx,
	}

	if err := s.worker.EnqueueJob(job); err != nil {
		log.Printf("Error enqueuing scan job: %v", err)
	} else {
		libraryIDStr := fmt.Sprintf("%x", libraryID.Bytes)
		log.Printf("Enqueued scan job %s for library %s", job.ID, libraryIDStr)
	}
}

func (s *Scheduler) UpdateScanSettings(userID string, enabled bool, frequencyMinutes int) {
	s.mu.Lock()
	defer s.mu.Unlock()

	s.scanSettings[userID] = ScanSetting{
		UserID:    userID,
		Enabled:   enabled,
		Frequency: frequencyMinutes,
	}
}