package main

import (
	"context"
	"database/sql"
	"embed"
	"fmt"
	"html/template"
	"log"
	"net/http"
	"os"
	"os/signal"
	"sync"
	"syscall"
	"time"

	"github.com/go-chi/chi/v5"
	"github.com/go-chi/chi/v5/middleware"
	_ "github.com/mattn/go-sqlite3"
	"github.com/ryanchen/bbq/db"
)

//go:embed templates/*.html
var templateFS embed.FS

//go:embed static/*
var staticFS embed.FS

//go:embed schema.sql
var schemaSQL string

var pageTmpl map[string]*template.Template

type Server struct {
	q       *db.Queries
	db      *sql.DB
	baseURL string

	// SSE: map of event slug -> set of channels
	mu      sync.Mutex
	clients map[string]map[chan struct{}]struct{}
}

func NewServer(database *sql.DB, baseURL string) *Server {
	return &Server{
		q:       db.New(database),
		db:      database,
		baseURL: baseURL,
		clients: make(map[string]map[chan struct{}]struct{}),
	}
}

func (s *Server) subscribe(slug string) chan struct{} {
	s.mu.Lock()
	defer s.mu.Unlock()
	ch := make(chan struct{}, 1)
	if s.clients[slug] == nil {
		s.clients[slug] = make(map[chan struct{}]struct{})
	}
	s.clients[slug][ch] = struct{}{}
	return ch
}

func (s *Server) unsubscribe(slug string, ch chan struct{}) {
	s.mu.Lock()
	defer s.mu.Unlock()
	if m, ok := s.clients[slug]; ok {
		delete(m, ch)
		if len(m) == 0 {
			delete(s.clients, slug)
		}
	}
}

func (s *Server) notify(slug string) {
	s.mu.Lock()
	defer s.mu.Unlock()
	for ch := range s.clients[slug] {
		select {
		case ch <- struct{}{}:
		default:
		}
	}
}

func main() {
	dbPath := "bbq.db"
	if v := os.Getenv("BBQ_DB"); v != "" {
		dbPath = v
	}
	port := "8080"
	if v := os.Getenv("PORT"); v != "" {
		port = v
	}
	baseURL := os.Getenv("BBQ_BASE_URL") // e.g. https://bbq.torrtle.co

	database, err := sql.Open("sqlite3", dbPath+"?_journal_mode=WAL&_foreign_keys=on")
	if err != nil {
		log.Fatal(err)
	}
	defer database.Close()
	database.SetMaxOpenConns(1)

	if _, err := database.Exec(schemaSQL); err != nil {
		log.Fatal("schema init: ", err)
	}
	runMigrations(database)

	funcMap := template.FuncMap{
		"pct": func(count, max int64) int64 {
			if max == 0 {
				return 0
			}
			return (count * 100) / max
		},
		"sub": func(a, b int64) int64 {
			return a - b
		},
	}

	// Parse each page with layout + shared partials
	pageTmpl = make(map[string]*template.Template)
	shared := []string{"templates/layout.html", "templates/slots.html"}
	for _, page := range []string{"home", "event"} {
		files := append([]string{"templates/" + page + ".html"}, shared...)
		pageTmpl[page] = template.Must(
			template.New("").Funcs(funcMap).ParseFS(templateFS, files...),
		)
	}
	// slots-only partial (for HTMX responses)
	pageTmpl["slots"] = template.Must(
		template.New("").Funcs(funcMap).ParseFS(templateFS, "templates/slots.html"),
	)

	srv := NewServer(database, baseURL)

	r := chi.NewRouter()
	r.Use(middleware.Logger)
	r.Use(middleware.Recoverer)

	// Static files
	r.Handle("/static/*", http.FileServer(http.FS(staticFS)))

	// Home / create event
	r.Get("/", srv.handleHome)
	r.Post("/events", srv.handleCreateEvent)

	// Guest event view
	r.Get("/e/{slug}", srv.handleEvent)
	r.Get("/e/{slug}/slots", srv.handleSlotsPartial)
	r.Post("/e/{slug}/claim", srv.handleClaim)
	r.Delete("/e/{slug}/claim/{claimID}", srv.handleUnclaim)
	r.Post("/e/{slug}/rsvp", srv.handleRsvp)
	r.Delete("/e/{slug}/rsvp/{rsvpID}", srv.handleUnrsvp)

	// OG image
	r.Get("/e/{slug}/og.png", srv.handleOGImage)

	// SSE
	r.Get("/e/{slug}/sse", srv.handleSSE)

	// Admin
	r.Get("/e/{slug}/admin/{token}", srv.handleAdmin)
	r.Post("/e/{slug}/admin/{token}/description", srv.handleUpdateDescription)
	r.Post("/e/{slug}/admin/{token}/slot", srv.handleCreateSlot)
	r.Delete("/e/{slug}/admin/{token}/slot/{slotID}", srv.handleDeleteSlot)

	server := &http.Server{Addr: ":" + port, Handler: r}

	go func() {
		sig := make(chan os.Signal, 1)
		signal.Notify(sig, syscall.SIGINT, syscall.SIGTERM)
		<-sig
		log.Println("shutting down...")
		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
		defer cancel()
		server.Shutdown(ctx)
	}()

	fmt.Printf("Listening on http://localhost:%s\n", port)
	if err := server.ListenAndServe(); err != http.ErrServerClosed {
		log.Fatal(err)
	}
}