package main

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

	"github.com/joho/godotenv"
)

// PunishmentStats mirrors Hypixel's /punishmentstats response.
type PunishmentStats struct {
	Success              bool  `json:"success"`
	WatchdogLastMinute   int64 `json:"watchdog_lastMinute"`
	WatchdogRollingDaily int64 `json:"watchdog_rollingDaily"`
	WatchdogTotal        int64 `json:"watchdog_total"`
	StaffRollingDaily    int64 `json:"staff_rollingDaily"`
	StaffTotal           int64 `json:"staff_total"`
}

type cachedStats struct {
	stats      *PunishmentStats
	fetchedAt  time.Time
	fetchError error
}

type server struct {
	apiKey      string
	client      *http.Client
	cacheTTL    time.Duration
	cacheMu     sync.RWMutex
	cache       cachedStats
}

func newServer(apiKey string, cacheTTL time.Duration) *server {
	return &server{
		apiKey:   apiKey,
		client:   &http.Client{Timeout: 10 * time.Second},
		cacheTTL: cacheTTL,
	}
}

func (s *server) fetchStats() (*PunishmentStats, error) {
	req, err := http.NewRequest(http.MethodGet, "https://api.hypixel.net/v2/punishmentstats", nil)
	if err != nil {
		return nil, err
	}
	req.Header.Set("API-Key", s.apiKey)

	resp, err := s.client.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("bad status: %s", resp.Status)
	}

	var stats PunishmentStats
	if err := json.NewDecoder(resp.Body).Decode(&stats); err != nil {
		return nil, err
	}
	if !stats.Success {
		return nil, fmt.Errorf("hypixel api reported failure")
	}
	return &stats, nil
}

func (s *server) getStats() (*PunishmentStats, error) {
	s.cacheMu.RLock()
	cache := s.cache
	s.cacheMu.RUnlock()

	if cache.stats != nil && time.Since(cache.fetchedAt) < s.cacheTTL {
		return cache.stats, nil
	}

	s.cacheMu.Lock()
	defer s.cacheMu.Unlock()

	// Double-check after acquiring write lock.
	if s.cache.stats != nil && time.Since(s.cache.fetchedAt) < s.cacheTTL {
		return s.cache.stats, nil
	}

	stats, err := s.fetchStats()
	s.cache = cachedStats{stats: stats, fetchedAt: time.Now(), fetchError: err}
	if err != nil {
		return nil, err
	}
	return stats, nil
}

func (s *server) handleStats(w http.ResponseWriter, r *http.Request) {
	stats, err := s.getStats()
	if err != nil {
		http.Error(w, fmt.Sprintf(`{"error":%q}`, err.Error()), http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	w.Header().Set("Access-Control-Allow-Origin", "*")
	if err := json.NewEncoder(w).Encode(stats); err != nil {
		log.Printf("encode response: %v", err)
	}
}

func handleHealth(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json")
	fmt.Fprint(w, `{"status":"ok"}`)
}

func main() {
	_ = godotenv.Load()

	apiKey := os.Getenv("HYPIXEL_API_KEY")
	if apiKey == "" {
		log.Fatal("HYPIXEL_API_KEY is required")
	}

	port := os.Getenv("PORT")
	if port == "" {
		port = "8080"
	}

	srv := newServer(apiKey, 10*time.Second)

	http.HandleFunc("/health", handleHealth)
	http.HandleFunc("/api/stats", srv.handleStats)

	log.Printf("api listening on :%s", port)
	if err := http.ListenAndServe(":"+port, nil); err != nil {
		log.Fatalf("server error: %v", err)
	}
}