package main

import (
	"context"
	"errors"
	"log"
	"net/http"
	"os"
	"os/signal"
	"strconv"
	"syscall"
	"time"

	"ts3monolith/internal/config"
	"ts3monolith/internal/rrd"
	"ts3monolith/internal/ts3"
	webapp "ts3monolith/internal/web"
)

func main() {
	log.SetFlags(log.LstdFlags | log.LUTC)
	cfg, err := config.Load()
	if err != nil {
		log.Fatal(err)
	}
	tq := &ts3.Query{Addr: cfg.TSQueryHost + ":" + strconv.Itoa(cfg.TSQueryPort), User: cfg.TSQueryUser, Password: cfg.TSQueryPassword, VoicePort: cfg.TSVoicePort, Timeout: cfg.TSQueryTimeout}
	rm := &rrd.Manager{Tool: cfg.RRDTool, Path: cfg.RRDPath, GraphDir: cfg.GraphDir}
	if err := rm.Validate(); err != nil {
		log.Fatal(err)
	}
	app, err := webapp.New(cfg, tq, rm)
	if err != nil {
		log.Fatal(err)
	}

	srv := &http.Server{Addr: cfg.ListenAddr, Handler: app.Handler(), ReadHeaderTimeout: 5 * time.Second, ReadTimeout: 10 * time.Second, WriteTimeout: 15 * time.Second, IdleTimeout: 60 * time.Second, MaxHeaderBytes: 16 << 10}
	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
	defer stop()
	go collect(ctx, cfg, tq, rm)
	go func() {
		<-ctx.Done()
		c, cancel := context.WithTimeout(context.Background(), 8*time.Second)
		defer cancel()
		_ = srv.Shutdown(c)
	}()
	log.Printf("listening on %s", cfg.ListenAddr)
	if err := srv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
		log.Fatal(err)
	}
}

func collect(ctx context.Context, cfg config.Config, tq *ts3.Query, rm *rrd.Manager) {
	run := func() {
		c, cancel := context.WithTimeout(ctx, cfg.TSQueryTimeout)
		n, err := tq.CountOnline(c)
		cancel()
		if err != nil {
			log.Printf("stats query failed: %v", err)
		}
		// Treat "query failed" and "query succeeded but nobody is online"
		// the same way: repeat the last known sample instead of writing 0.
		// This matches the original PHP app's collector exactly (it never
		// distinguished the two cases either). At a 1-minute sampling
		// interval a real but brief empty-server moment plots as a sharp
		// spike down to 0 and back up, which reads as broken/jagged far
		// more than it reads as useful information -- so, deliberately,
		// a true "server went empty for a while" no longer shows as 0 in
		// the graph, same trade-off the original app made.
		raw := n
		if n == 0 {
			c2, cancel2 := context.WithTimeout(ctx, 2*time.Second)
			last, lastErr := rm.Last(c2)
			cancel2()
			if lastErr != nil {
				log.Printf("collect: raw=0, rrd lastupdate failed (writing raw 0): %v", lastErr)
			} else {
				n = last
			}
		}
		// DEBUG=1 turns on a log line for every single collection cycle
		// (raw TS3 reading vs. what actually got written to the RRD) --
		// useful while diagnosing the stats collector, far too noisy to
		// leave on permanently (one line per STATS_INTERVAL, forever).
		if cfg.Debug {
			log.Printf("collect: raw=%d written=%d", raw, n)
		}
		c3, cancel3 := context.WithTimeout(ctx, 5*time.Second)
		defer cancel3()
		if err := rm.Update(c3, n); err != nil {
			log.Printf("rrd update failed: %v", err)
		}
	}
	run()
	t := time.NewTicker(cfg.StatsInterval)
	defer t.Stop()
	for {
		select {
		case <-ctx.Done():
			return
		case <-t.C:
			run()
		}
	}
}