package stats

import (
	"encoding/json"
	"log"
	"net/http"
	"os"
	"sync"
	"sync/atomic"
	"time"

	"software-station/internal/models"

	"golang.org/x/time/rate"
)

type Service struct {
	HashesFile  string
	KnownHashes struct {
		sync.RWMutex
		Data map[string]*models.FingerprintData
	}
	GlobalStats struct {
		sync.RWMutex
		UniqueRequests    map[string]bool
		SuccessDownloads  map[string]bool
		BlockedRequests   map[string]bool
		LimitedRequests   map[string]bool
		WebRequests       map[string]bool
		TotalResponseTime time.Duration
		TotalRequests     int64
		TotalBytes        int64
		StartTime         time.Time
	}
	DownloadStats struct {
		sync.RWMutex
		Limiters map[string]*rate.Limiter
	}
	hashesDirty int32
	stopChan    chan struct{}
}

func NewService(hashesFile string) *Service {
	s := &Service{
		HashesFile: hashesFile,
		stopChan:   make(chan struct{}),
	}
	s.KnownHashes.Data = make(map[string]*models.FingerprintData)
	s.GlobalStats.UniqueRequests = make(map[string]bool)
	s.GlobalStats.SuccessDownloads = make(map[string]bool)
	s.GlobalStats.BlockedRequests = make(map[string]bool)
	s.GlobalStats.LimitedRequests = make(map[string]bool)
	s.GlobalStats.WebRequests = make(map[string]bool)
	s.GlobalStats.StartTime = time.Now()
	s.DownloadStats.Limiters = make(map[string]*rate.Limiter)
	return s
}

func (s *Service) Start() {
	go func() {
		ticker := time.NewTicker(10 * time.Second)
		statsTicker := time.NewTicker(24 * time.Hour)
		defer ticker.Stop()
		defer statsTicker.Stop()
		for {
			select {
			case <-ticker.C:
				if atomic.CompareAndSwapInt32(&s.hashesDirty, 1, 0) {
					s.FlushHashes()
				}
			case <-statsTicker.C:
				s.ResetGlobalStats()
			case <-s.stopChan:
				s.FlushHashes()
				return
			}
		}
	}()
}

func (s *Service) ResetGlobalStats() {
	s.GlobalStats.Lock()
	defer s.GlobalStats.Unlock()
	s.GlobalStats.UniqueRequests = make(map[string]bool)
	s.GlobalStats.SuccessDownloads = make(map[string]bool)
	s.GlobalStats.BlockedRequests = make(map[string]bool)
	s.GlobalStats.LimitedRequests = make(map[string]bool)
	s.GlobalStats.WebRequests = make(map[string]bool)
	s.GlobalStats.TotalRequests = 0
	s.GlobalStats.TotalResponseTime = 0
	s.GlobalStats.StartTime = time.Now()
}

func (s *Service) Stop() {
	close(s.stopChan)
}

func (s *Service) LoadHashes() {
	data, err := os.ReadFile(s.HashesFile)
	if err != nil {
		if !os.IsNotExist(err) {
			log.Printf("Error reading hashes file: %v", err)
		}
		return
	}
	s.KnownHashes.Lock()
	defer s.KnownHashes.Unlock()
	if err := json.Unmarshal(data, &s.KnownHashes.Data); err != nil {
		log.Printf("Error unmarshaling hashes: %v", err)
		return
	}

	var total int64
	for _, d := range s.KnownHashes.Data {
		total += atomic.LoadInt64(&d.TotalBytes)
	}
	atomic.StoreInt64(&s.GlobalStats.TotalBytes, total)
}

func (s *Service) SaveHashes() {
	atomic.StoreInt32(&s.hashesDirty, 1)
}

func (s *Service) FlushHashes() {
	s.KnownHashes.RLock()
	data, err := json.MarshalIndent(s.KnownHashes.Data, "", "  ")
	s.KnownHashes.RUnlock()
	if err != nil {
		log.Printf("Error marshaling hashes: %v", err)
		return
	}
	if err := os.WriteFile(s.HashesFile, data, 0600); err != nil {
		log.Printf("Error writing hashes file: %v", err)
	}
}

func (s *Service) APIStatsHandler(w http.ResponseWriter, r *http.Request) {
	s.GlobalStats.RLock()
	defer s.GlobalStats.RUnlock()

	avgResponse := time.Duration(0)
	if s.GlobalStats.TotalRequests > 0 {
		avgResponse = s.GlobalStats.TotalResponseTime / time.Duration(s.GlobalStats.TotalRequests)
	}

	totalBytes := atomic.LoadInt64(&s.GlobalStats.TotalBytes)
	uptime := time.Since(s.GlobalStats.StartTime)
	avgSpeed := float64(totalBytes) / uptime.Seconds()

	status := "healthy"
	if s.GlobalStats.TotalRequests > 0 && float64(len(s.GlobalStats.BlockedRequests))/float64(s.GlobalStats.TotalRequests) > 0.5 {
		status = "unhealthy"
	}

	data := map[string]interface{}{
		"total_unique_download_requests": len(s.GlobalStats.UniqueRequests),
		"total_unique_success_downloads": len(s.GlobalStats.SuccessDownloads),
		"total_unique_blocked":           len(s.GlobalStats.BlockedRequests),
		"total_unique_limited":           len(s.GlobalStats.LimitedRequests),
		"total_unique_web_requests":      len(s.GlobalStats.WebRequests),
		"avg_speed_bps":                  avgSpeed,
		"avg_response_time":              avgResponse.String(),
		"uptime":                         uptime.String(),
		"status":                         status,
	}

	w.Header().Set("Content-Type", "application/json")
	if err := json.NewEncoder(w).Encode(data); err != nil {
		log.Printf("Error encoding stats: %v", err)
	}
}