package server

import (
	"fmt"
	"html"
	"io/fs"
	"log"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"sync"
	"time"

	webbundle "luxtools/web"
)

const (
	address          = ":5000"
	htmlContentType  = "text/html; charset=utf-8"
	notFoundTemplate = `
		<div class="tui-window">
			<fieldset class="tui-fieldset">
				<legend>Error</legend>
				<p>Route %s not found.</p>
			</fieldset>
		</div>
		`
)

// Config contains the runtime options for the HTTP server.
type Config struct {
	MediaDir string
}

// Server hosts the Luxtools HTTP handlers.
type Server struct {
	mux       *http.ServeMux
	indexPage []byte
	staticFS  fs.FS
	mediaFS   http.FileSystem

	counterMu  sync.Mutex
	clickCount int
}

// New constructs a configured Server ready to serve requests.
func New(cfg Config) (*Server, error) {
	if strings.TrimSpace(cfg.MediaDir) == "" {
		return nil, fmt.Errorf("media directory is required")
	}

	mediaDir := filepath.Clean(cfg.MediaDir)

	info, err := os.Stat(mediaDir)
	if err != nil {
		return nil, fmt.Errorf("media directory check failed: %w", err)
	}
	if !info.IsDir() {
		return nil, fmt.Errorf("media directory must be a directory: %s", mediaDir)
	}

	indexPage, err := webbundle.Content.ReadFile("templates/index.html")
	if err != nil {
		return nil, fmt.Errorf("failed to read index template: %w", err)
	}

	staticFS, err := fs.Sub(webbundle.Content, "static")
	if err != nil {
		return nil, fmt.Errorf("failed to prepare static assets: %w", err)
	}

	s := &Server{
		mux:       http.NewServeMux(),
		indexPage: indexPage,
		staticFS:  staticFS,
		mediaFS:   http.Dir(mediaDir),
	}

	s.registerRoutes()
	return s, nil
}

// Router exposes the configured http.Handler for the server.
func (s *Server) Router() http.Handler {
	return s.mux
}

// Address returns the default listen address for the server.
func (s *Server) Address() string {
	return address
}

func (s *Server) registerRoutes() {
	staticHandler := http.FileServer(http.FS(s.staticFS))
	mediaHandler := http.FileServer(s.mediaFS)

	s.mux.Handle("/static/", http.StripPrefix("/static/", allowGetHead(staticHandler)))
	s.mux.Handle("/media/", http.StripPrefix("/media/", allowGetHead(mediaHandler)))
	s.mux.HandleFunc("/", s.handleRequest)
}

func (s *Server) handleRequest(w http.ResponseWriter, r *http.Request) {
	switch r.URL.Path {
	case "/":
		s.sendHTML(w, http.StatusOK, s.indexPage)
	case "/counter":
		s.handleCounter(w, r)
	case "/time":
		s.sendHTMLString(w, http.StatusOK, renderTime(time.Now()))
	default:
		s.sendHTMLString(w, http.StatusNotFound, fmt.Sprintf(notFoundTemplate, html.EscapeString(r.URL.Path)))
	}
}

func (s *Server) handleCounter(w http.ResponseWriter, r *http.Request) {
	if r.Method == http.MethodPost || r.Method == http.MethodPut {
		s.counterMu.Lock()
		s.clickCount++
		s.counterMu.Unlock()
	}

	s.counterMu.Lock()
	count := s.clickCount
	s.counterMu.Unlock()

	s.sendHTMLString(w, http.StatusOK, renderCounter(count))
}

func (s *Server) sendHTML(w http.ResponseWriter, status int, body []byte) {
	w.Header().Set("Content-Type", htmlContentType)
	w.WriteHeader(status)
	if len(body) > 0 {
		if _, err := w.Write(body); err != nil {
			log.Printf("write response failed: %v", err)
		}
	}
}

func (s *Server) sendHTMLString(w http.ResponseWriter, status int, body string) {
	s.sendHTML(w, status, []byte(body))
}

func renderCounter(count int) string {
	return fmt.Sprintf(`
  <div id="counter" class="tui-panel tui-panel-inline">
    <p><strong>Clicks:</strong> %d</p>
    <button class="tui-button" hx-post="/counter" hx-target="#counter" hx-swap="outerHTML">
      Increment
    </button>
  </div>
  `, count)
}

func renderTime(now time.Time) string {
	return fmt.Sprintf(`
  <div id="server-time" class="tui-panel tui-panel-inline">
    <p><strong>Server time:</strong> %s</p>
  </div>
  `, now.Format("2006-01-02 15:04:05"))
}

func allowGetHead(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		switch r.Method {
		case http.MethodGet, http.MethodHead:
			next.ServeHTTP(w, r)
		default:
			http.NotFound(w, r)
		}
	})
}