package main

import (
	"context"
	"flag"
	"fmt"
	"log"
	"net/http"
	"os"
	"os/signal"
	"path/filepath"
	"strings"
	"sync"
	"syscall"
	"time"

	"github.com/Sendspin/sendspin-go/pkg/discovery"
	"github.com/Sendspin/sendspin-go/pkg/sendspin"
	"github.com/gorilla/websocket"

	"rpi-sendspin/internal/pipewire"
)

func main() {
	server := flag.String("server", "", "server address for client-initiated mode (dial out). Leave empty for server-initiated mode: advertise via mDNS and wait for the server to connect.")
	name := flag.String("name", hostname(), "player name")
	device := flag.String("device", "", "PipeWire sink node name (default: system default)")
	listDevices := flag.Bool("list-devices", false, "list available PipeWire sinks and exit")
	volume := flag.Int("volume", 80, "initial volume (0-100)")
	mdnsPort := flag.Int("mdns-port", 8928, "port to advertise in mDNS (_sendspin._tcp)")
	noMDNS := flag.Bool("no-mdns", false, "disable mDNS advertisement")
	muteLoopback := flag.String("mute-loopback", "", "PipeWire node.name of a loopback to mute while streaming from --mute-server (requires --mute-server)")
	muteServer := flag.String("mute-server", "", "server address that arms loopback muting; must match --server (requires --mute-loopback)")
	flag.Parse()

	if *listDevices {
		sinks, err := pipewire.ListSinks()
		if err != nil {
			log.Fatalf("list sinks: %v", err)
		}
		if len(sinks) == 0 {
			fmt.Println("no PipeWire sinks found")
			return
		}
		fmt.Println("Available PipeWire sinks:")
		for _, s := range sinks {
			fmt.Printf("  %s\n", s)
		}
		return
	}

	idFile := clientIDFile()
	savedID, _ := os.ReadFile(idFile)
	clientID, err := sendspin.ResolveClientID("", string(savedID), func(id string) error {
		if err := os.MkdirAll(filepath.Dir(idFile), 0700); err != nil {
			return err
		}
		return os.WriteFile(idFile, []byte(id), 0600)
	})
	if err != nil {
		log.Fatalf("resolve client ID: %v", err)
	}

	if !*noMDNS {
		disc := discovery.NewManager(discovery.Config{
			ServiceName: *name,
			Port:        *mdnsPort,
		})
		if err := disc.Advertise(); err != nil {
			log.Printf("mdns advertise: %v", err)
		} else {
			defer disc.Stop()
		}
	}

	output := pipewire.NewOutput(*device, *name)

	muter := buildMuter(*server, *muteServer, *muteLoopback)

	player, err := sendspin.NewPlayer(sendspin.PlayerConfig{
		ServerAddr: *server,
		PlayerName: *name,
		ClientID:   clientID,
		Volume:     *volume,
		Output:     output,
		Reconnect: sendspin.ReconnectConfig{
			Enabled:      true,
			InitialDelay: 2 * time.Second,
			MaxDelay:     30 * time.Second,
			Multiplier:   2.0,
		},
		OnMetadata: func(meta sendspin.Metadata) {
			if meta.Artist != "" || meta.Title != "" {
				log.Printf("now playing: %s — %s", meta.Artist, meta.Title)
			}
		},
		OnStateChange: func(s sendspin.PlayerState) {
			if muter != nil {
				muter.SetDesiredMute(s.State == "playing")
			}
		},
		OnError: func(err error) {
			log.Printf("error: %v", err)
		},
	})
	if err != nil {
		log.Fatalf("create player: %v", err)
	}
	// LIFO: muter.Stop runs AFTER player.Close, so the player has stopped
	// emitting "playing" state by the time we force the final unmute.
	if muter != nil {
		defer func() {
			ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
			defer cancel()
			muter.Stop(ctx)
		}()
	}
	defer player.Close()

	if *device != "" {
		log.Printf("output: %s", *device)
	} else {
		log.Printf("output: PipeWire default sink")
	}

	sig := make(chan os.Signal, 1)
	signal.Notify(sig, os.Interrupt, syscall.SIGTERM)

	if *server == "" {
		// Server-initiated mode: the server discovers us via mDNS and dials
		// our /sendspin endpoint. We just listen and let player.Accept drive
		// each connection.
		if *noMDNS {
			log.Printf("warning: --no-mdns with no --server — the server cannot discover this player")
		}
		runServerInitiated(player, *mdnsPort, sig)
	} else {
		// Client-initiated mode: dial the configured server.
		log.Printf("connecting to %s as %q...", *server, *name)
		if err := player.Connect(); err != nil {
			log.Fatalf("connect: %v", err)
		}
		if err := player.Play(); err != nil {
			log.Fatalf("play: %v", err)
		}
		<-sig
	}

	log.Println("stopping")
	player.Stop()
}

// runServerInitiated runs an HTTP/WebSocket server on the mDNS-advertised
// port and hands each accepted /sendspin connection to player.Accept. Only
// one session runs at a time; a newer connection evicts the current one
// (newest-wins) so a server that reconnects isn't blocked behind a stale
// socket. Blocks until a signal arrives on sig.
func runServerInitiated(player *sendspin.Player, port int, sig <-chan os.Signal) {
	upgrader := websocket.Upgrader{
		CheckOrigin: func(*http.Request) bool { return true },
	}

	var (
		mu      sync.Mutex // serializes sessions; held for a connection's lifetime
		connMu  sync.Mutex // guards curConn
		curConn *websocket.Conn
	)

	handler := func(w http.ResponseWriter, r *http.Request) {
		conn, err := upgrader.Upgrade(w, r, nil)
		if err != nil {
			log.Printf("websocket upgrade failed: %v", err)
			return
		}

		// Evict any in-flight session so its Accept returns and releases mu.
		connMu.Lock()
		if curConn != nil {
			curConn.Close()
		}
		curConn = conn
		connMu.Unlock()

		mu.Lock()
		defer mu.Unlock()

		// We may have been superseded while waiting for the lock.
		connMu.Lock()
		superseded := curConn != conn
		connMu.Unlock()
		if superseded {
			conn.Close()
			return
		}

		if err := player.Accept(conn); err != nil {
			log.Printf("session ended: %v", err)
		}

		connMu.Lock()
		if curConn == conn {
			curConn = nil
		}
		connMu.Unlock()
	}

	mux := http.NewServeMux()
	mux.HandleFunc("/sendspin", handler)
	srv := &http.Server{Addr: fmt.Sprintf(":%d", port), Handler: mux}

	go func() {
		log.Printf("server-initiated mode: listening on :%d/sendspin, waiting for a server to connect", port)
		if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
			log.Fatalf("listen: %v", err)
		}
	}()

	<-sig

	// Drop the active session first so the blocked handler returns, then let
	// Shutdown drain the (now-unblocked) server.
	player.CloseConnection()
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()
	srv.Shutdown(ctx)
}

func hostname() string {
	h, _ := os.Hostname()
	if h == "" {
		return "sendspin-player"
	}
	return h
}

// buildMuter wires up the loopback muter when both --mute-loopback and
// --mute-server are set AND --mute-server matches the configured --server.
// Mismatches are intentional silent no-ops so the same config file can ship
// to machines where the server happens to be different — only logged so
// it's visible. Returns nil when muting is disabled.
//
// The address check is a startup-time string compare; mDNS rediscovery
// during reconnect could in theory move the player to a different server,
// but for the same-machine echo-cancel use case that's acceptable.
func buildMuter(server, muteServer, muteLoopback string) *pipewire.Muter {
	if muteLoopback == "" {
		if muteServer != "" {
			log.Printf("muter: --mute-server set without --mute-loopback; loopback mute disabled")
		}
		return nil
	}
	// Server-initiated (listen) mode has no fixed --server to compare
	// against, so arm the muter purely on --mute-loopback.
	if server == "" {
		log.Printf("muter: will mute PipeWire node %q while streaming (server-initiated mode)", muteLoopback)
		return pipewire.NewMuter(muteLoopback)
	}
	if muteServer == "" {
		log.Printf("muter: --mute-loopback and --mute-server must be set together in client-initiated mode; loopback mute disabled")
		return nil
	}
	if !sameServerAddr(server, muteServer) {
		log.Printf("muter: --mute-server %q != --server %q; loopback mute disabled", muteServer, server)
		return nil
	}
	log.Printf("muter: will mute PipeWire node %q while streaming from %s", muteLoopback, server)
	return pipewire.NewMuter(muteLoopback)
}

// sameServerAddr normalizes two host[:port] strings for equality so
// "localhost" and "localhost:8927" compare equal when 8927 is the default.
func sameServerAddr(a, b string) bool {
	const defaultPort = "8927"
	norm := func(s string) string {
		s = strings.TrimSpace(strings.ToLower(s))
		if !strings.Contains(s, ":") {
			s += ":" + defaultPort
		}
		return s
	}
	return norm(a) == norm(b)
}

func clientIDFile() string {
	dir, err := os.UserConfigDir()
	if err != nil {
		dir = os.TempDir()
	}
	return filepath.Join(dir, "rpi-sendspin", "client_id")
}