//go:build windows

// Package server wires together the HTTP API, WebSocket hub, Winamp controller,
// WASAPI viz capture, killist, and resume.
package server

import (
	"context"
	"encoding/json"
	"fmt"
	"io/fs"
	"log"
	"net/http"
	"os"
	"os/exec"
	"strconv"
	"time"

	"git.svabi.ch/jan/roadamp/internal/killist"
	"git.svabi.ch/jan/roadamp/internal/resume"
	"git.svabi.ch/jan/roadamp/internal/volume"
	"git.svabi.ch/jan/roadamp/internal/viz"
	"git.svabi.ch/jan/roadamp/internal/winamp"
	"github.com/gorilla/websocket"
	"gopkg.in/yaml.v3"
)

// ── Config ────────────────────────────────────────────────────────────────────

type Config struct {
	Port         int    `yaml:"port"`
	WinampPath   string `yaml:"winamp_path"`
	KillListFile string `yaml:"killist_file"`
	ResumeFile   string `yaml:"resume_file"`
}

func loadConfig(path string) (Config, error) {
	cfg := Config{
		Port:         8080,
		KillListFile: "killist.dat",
		ResumeFile:   "resume.dat",
	}
	data, err := os.ReadFile(path)
	if os.IsNotExist(err) {
		return cfg, nil
	}
	if err != nil {
		return cfg, err
	}
	return cfg, yaml.Unmarshal(data, &cfg)
}

// ── Server ────────────────────────────────────────────────────────────────────

type Server struct {
	cfg      Config
	wa       *winamp.Controller
	kl       *killist.KillList
	hub      *hub
	mux      *http.ServeMux
	staticFS fs.FS
}

func New(configPath string, staticFS fs.FS) (*Server, error) {
	cfg, err := loadConfig(configPath)
	if err != nil {
		return nil, fmt.Errorf("config: %w", err)
	}
	kl, err := killist.Load(cfg.KillListFile)
	if err != nil {
		return nil, fmt.Errorf("killist: %w", err)
	}
	s := &Server{cfg: cfg, wa: winamp.New(), kl: kl, mux: http.NewServeMux(), staticFS: staticFS}
	s.hub = newHub(s.handleCommand)
	s.routes()
	return s, nil
}

func (s *Server) Run() error {
	go s.hub.run()
	go s.broadcastStatus()
	go s.broadcastViz()
	go s.restoreResume()
	go s.killChecker()

	addr := fmt.Sprintf(":%d", s.cfg.Port)
	log.Printf("roadamp listening on http://localhost%s", addr)
	return http.ListenAndServe(addr, s.mux)
}

// ── Routes ────────────────────────────────────────────────────────────────────

func (s *Server) routes() {
	s.mux.Handle("/", http.FileServer(http.FS(s.staticFS)))

	// WebSocket (primary interface)
	s.mux.HandleFunc("/ws", s.handleWS)

	// REST API (kept for curl/debugging)
	s.mux.HandleFunc("/api/status", s.handleStatus)
	s.mux.HandleFunc("/api/play", s.handlePlay)
	s.mux.HandleFunc("/api/pause", s.handlePause)
	s.mux.HandleFunc("/api/stop", s.handleStop)
	s.mux.HandleFunc("/api/next", s.handleNext)
	s.mux.HandleFunc("/api/prev", s.handlePrev)
	s.mux.HandleFunc("/api/seek", s.handleSeek)
	s.mux.HandleFunc("/api/volume", s.handleVolume)
	s.mux.HandleFunc("/api/mute", s.handleMute)
	s.mux.HandleFunc("/api/killist", s.handleKillist)
	s.mux.HandleFunc("/api/winamp/start", s.handleWinampStart)
}

// ── WebSocket ─────────────────────────────────────────────────────────────────

var wsUpgrader = websocket.Upgrader{
	ReadBufferSize:  1024,
	WriteBufferSize: 4096,
	CheckOrigin:     func(r *http.Request) bool { return true },
}

func (s *Server) handleWS(w http.ResponseWriter, r *http.Request) {
	conn, err := wsUpgrader.Upgrade(w, r, nil)
	if err != nil {
		log.Printf("ws upgrade: %v", err)
		return
	}
	c := &wsClient{hub: s.hub, conn: conn, send: make(chan []byte, 32)}
	s.hub.register <- c

	// Send current status immediately upon connect.
	if msg, err := s.statusMsg(); err == nil {
		c.send <- msg
	}

	go c.writePump()
	go c.readPump()
}

// ── WebSocket broadcast workers ───────────────────────────────────────────────

// broadcastStatus pushes a status message to all clients every 500 ms.
func (s *Server) broadcastStatus() {
	for range time.Tick(500 * time.Millisecond) {
		msg, err := s.statusMsg()
		if err != nil {
			continue
		}
		select {
		case s.hub.broadcast <- msg:
		default:
		}
	}
}

// broadcastViz starts the WASAPI loopback capturer and forwards spectrum
// frames to all WebSocket clients at ~30 fps.
func (s *Server) broadcastViz() {
	cap := viz.NewCapturer()
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	go cap.Start(ctx)

	for bars := range cap.C {
		data, err := json.Marshal(struct {
			Type string    `json:"type"`
			Bars []float32 `json:"bars"`
		}{"viz", bars})
		if err != nil {
			continue
		}
		select {
		case s.hub.broadcast <- data:
		default:
		}
	}
}

// ── Command dispatcher (WebSocket) ────────────────────────────────────────────

type wsCommand struct {
	Cmd   string `json:"cmd"`
	Delta int    `json:"delta"`
	Level int    `json:"level"`
	Muted bool   `json:"muted"`
	Title string `json:"title"`
}

func (s *Server) handleCommand(raw []byte) {
	var cmd wsCommand
	if err := json.Unmarshal(raw, &cmd); err != nil {
		return
	}
	switch cmd.Cmd {
	case "play":
		s.wa.Play()
	case "pause":
		s.wa.Pause()
	case "stop":
		if s.wa.IsPaused() {
			_ = resume.Save(s.cfg.ResumeFile, resume.State{
				PlaylistLength: s.wa.GetPlaylistLength(),
				PlaylistPos:    s.wa.GetPlaylistPosition(),
				OffsetSeconds:  s.wa.GetPosition(),
				TrackTitle:     s.wa.GetTitle(),
			})
		}
		s.wa.Stop()
	case "next":
		s.wa.NextTrack()
	case "prev":
		s.wa.PrevTrack()
	case "seek":
		pos := s.wa.GetPosition() + cmd.Delta
		if pos < 0 {
			pos = 0
		}
		s.wa.Seek(pos)
	case "volume":
		_ = volume.Set(cmd.Level)
	case "mute":
		_ = volume.SetMute(cmd.Muted)
	case "killist_add":
		if title := s.wa.GetTitle(); title != "" {
			_ = s.kl.Add(title)
		}
	case "killist_remove":
		_ = s.kl.Remove(cmd.Title)
	case "winamp_start":
		if !s.wa.IsRunning() {
			if s.cfg.WinampPath != "" {
				_ = exec.Command(s.cfg.WinampPath).Start()
			}
		}
	}
	// Push a fresh status after any command.
	if msg, err := s.statusMsg(); err == nil {
		select {
		case s.hub.broadcast <- msg:
		default:
		}
	}
}

// ── Shared status builder ─────────────────────────────────────────────────────

type statusMsg struct {
	Type           string `json:"type"`
	Running        bool   `json:"running"`
	State          string `json:"state"`
	Title          string `json:"title"`
	Position       int    `json:"position"`
	Length         int    `json:"length"`
	PlaylistPos    int    `json:"playlist_pos"`
	PlaylistLength int    `json:"playlist_length"`
	Version        string `json:"version"`
	Volume         int    `json:"volume"`
	Muted          bool   `json:"muted"`
}

func (s *Server) statusMsg() ([]byte, error) {
	msg := statusMsg{Type: "status", Running: s.wa.IsRunning()}
	if msg.Running {
		switch s.wa.PlayState() {
		case 1:
			msg.State = "playing"
		case 3:
			msg.State = "paused"
		default:
			msg.State = "stopped"
		}
		msg.Title = s.wa.GetTitle()
		// Winamp returns 0xFFFFFFFF when stopped/no track — clamp to 0.
		pos := s.wa.GetPosition()
		length := s.wa.GetLength()
		if pos > 86400 { pos = 0 }      // > 24h → garbage value
		if length > 86400 { length = 0 }
		msg.Position = pos
		msg.Length = length
		msg.PlaylistPos = s.wa.GetPlaylistPosition()
		msg.PlaylistLength = s.wa.GetPlaylistLength()
		msg.Version = s.wa.GetVersion()
	}
	if vol, err := volume.Get(); err == nil {
		msg.Volume = vol
	}
	if muted, err := volume.GetMute(); err == nil {
		msg.Muted = muted
	}
	return json.Marshal(msg)
}

// ── Background workers ────────────────────────────────────────────────────────

func (s *Server) killChecker() {
	for range time.Tick(2 * time.Second) {
		if !s.wa.IsPlaying() {
			continue
		}
		if title := s.wa.GetTitle(); s.kl.Contains(title) {
			log.Printf("killist: skipping %q", title)
			s.wa.NextTrack()
		}
	}
}

func (s *Server) restoreResume() {
	deadline := time.Now().Add(30 * time.Second)
	for time.Now().Before(deadline) {
		if s.wa.IsRunning() {
			break
		}
		time.Sleep(500 * time.Millisecond)
	}
	st, err := resume.Load(s.cfg.ResumeFile)
	if err != nil || st == nil {
		return
	}
	if s.wa.GetPlaylistLength() != st.PlaylistLength {
		_ = resume.Delete(s.cfg.ResumeFile)
		return
	}
	s.wa.Play()
	s.wa.Seek(st.OffsetSeconds)
	s.wa.Pause()
	_ = resume.Delete(s.cfg.ResumeFile)
	log.Printf("resume: restored %q at %ds", st.TrackTitle, st.OffsetSeconds)
}

// ── REST handlers (for curl/debug) ───────────────────────────────────────────

func (s *Server) handleStatus(w http.ResponseWriter, r *http.Request) {
	msg, err := s.statusMsg()
	if err != nil {
		http.Error(w, err.Error(), 500)
		return
	}
	w.Header().Set("Content-Type", "application/json")
	w.Write(msg)
}

func (s *Server) handlePlay(w http.ResponseWriter, r *http.Request)  { jsonOK(w, s.wa.Play()) }
func (s *Server) handlePause(w http.ResponseWriter, r *http.Request) { jsonOK(w, s.wa.Pause()) }
func (s *Server) handleNext(w http.ResponseWriter, r *http.Request)  { jsonOK(w, s.wa.NextTrack()) }
func (s *Server) handlePrev(w http.ResponseWriter, r *http.Request)  { jsonOK(w, s.wa.PrevTrack()) }

func (s *Server) handleStop(w http.ResponseWriter, r *http.Request) {
	if s.wa.IsPaused() {
		_ = resume.Save(s.cfg.ResumeFile, resume.State{
			PlaylistLength: s.wa.GetPlaylistLength(),
			PlaylistPos:    s.wa.GetPlaylistPosition(),
			OffsetSeconds:  s.wa.GetPosition(),
			TrackTitle:     s.wa.GetTitle(),
		})
	}
	jsonOK(w, s.wa.Stop())
}

func (s *Server) handleSeek(w http.ResponseWriter, r *http.Request) {
	delta, err := strconv.Atoi(r.URL.Query().Get("delta"))
	if err != nil {
		http.Error(w, "invalid delta", http.StatusBadRequest)
		return
	}
	pos := s.wa.GetPosition() + delta
	if pos < 0 {
		pos = 0
	}
	jsonOK(w, s.wa.Seek(pos))
}

func (s *Server) handleVolume(w http.ResponseWriter, r *http.Request) {
	if r.Method == http.MethodGet {
		vol, _ := volume.Get()
		jsonOK(w, map[string]int{"volume": vol})
		return
	}
	lvl, err := strconv.Atoi(r.URL.Query().Get("level"))
	if err != nil {
		http.Error(w, "invalid level", http.StatusBadRequest)
		return
	}
	_ = volume.Set(lvl)
	jsonOK(w, map[string]int{"volume": lvl})
}

func (s *Server) handleMute(w http.ResponseWriter, r *http.Request) {
	if r.Method == http.MethodGet {
		muted, _ := volume.GetMute()
		jsonOK(w, map[string]bool{"muted": muted})
		return
	}
	val := r.URL.Query().Get("muted")
	muted := val == "true" || val == "1"
	_ = volume.SetMute(muted)
	jsonOK(w, map[string]bool{"muted": muted})
}

func (s *Server) handleKillist(w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	case http.MethodGet:
		jsonOK(w, s.kl.List())
	case http.MethodPost:
		title := s.wa.GetTitle()
		if title == "" {
			http.Error(w, "no track playing", http.StatusConflict)
			return
		}
		_ = s.kl.Add(title)
		jsonOK(w, map[string]string{"added": title})
	case http.MethodDelete:
		_ = s.kl.Remove(r.URL.Query().Get("title"))
		jsonOK(w, map[string]bool{"ok": true})
	}
}

func (s *Server) handleWinampStart(w http.ResponseWriter, r *http.Request) {
	if s.wa.IsRunning() {
		jsonOK(w, map[string]string{"status": "already_running"})
		return
	}
	if s.cfg.WinampPath == "" {
		http.Error(w, "winamp_path not configured", http.StatusServiceUnavailable)
		return
	}
	if err := exec.Command(s.cfg.WinampPath).Start(); err != nil {
		http.Error(w, err.Error(), 500)
		return
	}
	jsonOK(w, map[string]string{"status": "started"})
}

func jsonOK(w http.ResponseWriter, v any) {
	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(v)
}