package admin

import (
	"context"
	_ "embed"
	"html/template"
	"net/http"
	"strconv"
	"strings"
	"time"

	"git.send.nrw/sendnrw/decent-webui/internal/filesvc"
	"git.send.nrw/sendnrw/decent-webui/internal/mesh"
)

/*** Templates einbetten ***/

//go:embed tpl/layout.html
var layoutHTML string

//go:embed tpl/partials_items.html
var itemsPartialHTML string

//go:embed tpl/partials_peers.html
var peersPartialHTML string

var (
	tplLayout = template.Must(template.New("layout").Parse(layoutHTML))
	tplItems  = template.Must(template.New("items").Funcs(template.FuncMap{
		"timeRFC3339": func(unixNano int64) string {
			if unixNano == 0 {
				return ""
			}
			return time.Unix(0, unixNano).UTC().Format(time.RFC3339)
		},
	}).Parse(itemsPartialHTML))
	tplPeers = template.Must(template.New("peers").Parse(peersPartialHTML))
)

type Deps struct {
	Store filesvc.MeshStore
	Mesh  *mesh.Node
}

// Register hängt alle /admin Routen ein.
// Auth liegt optional VOR Register (BasicAuth-Middleware), siehe main.go.
func Register(mux *http.ServeMux, d Deps) {
	// Dashboard
	mux.HandleFunc("/admin", func(w http.ResponseWriter, r *http.Request) {
		renderLayout(w, r, "Files", "/admin/items")
	})

	// Partials
	mux.HandleFunc("/admin/items", func(w http.ResponseWriter, r *http.Request) {
		// Liste rendern (Pagination optional via ?next=)
		nextQ := strings.TrimSpace(r.URL.Query().Get("next"))
		var nextID filesvc.ID
		if nextQ != "" {
			if n, err := strconv.ParseInt(nextQ, 10, 64); err == nil {
				nextID = filesvc.ID(n)
			}
		}
		items, nextOut, _ := d.Store.List(r.Context(), nextID, 100)
		_ = tplItems.Execute(w, map[string]any{
			"Items": items,
			"Next":  nextOut,
		})
	})

	mux.HandleFunc("/admin/peers", func(w http.ResponseWriter, r *http.Request) {
		peers := d.Mesh.PeerList()
		_ = tplPeers.Execute(w, map[string]any{
			"Peers": peers,
			"Now":   time.Now(),
		})
	})

	// Actions (HTMX POSTs)
	mux.HandleFunc("/admin/items/create", func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
			return
		}
		name := strings.TrimSpace(r.FormValue("name"))
		if name != "" {
			_, _ = d.Store.Create(r.Context(), name)
			_ = d.Mesh.SyncNow(r.Context()) // prompt push (best effort)
		}
		// Nach Aktion Items partial zurückgeben (HTMX swap)
		http.Redirect(w, r, "/admin/items", http.StatusSeeOther)
	})

	mux.HandleFunc("/admin/items/rename", func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
			return
		}
		idStr := r.FormValue("id")
		newName := strings.TrimSpace(r.FormValue("name"))
		if id, err := strconv.ParseInt(idStr, 10, 64); err == nil && newName != "" {
			_, _ = d.Store.Rename(r.Context(), filesvc.ID(id), newName)
			_ = d.Mesh.SyncNow(r.Context())
		}
		http.Redirect(w, r, "/admin/items", http.StatusSeeOther)
	})

	mux.HandleFunc("/admin/items/delete", func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
			return
		}
		if id, err := strconv.ParseInt(r.FormValue("id"), 10, 64); err == nil {
			_, _ = d.Store.Delete(r.Context(), filesvc.ID(id))
			_ = d.Mesh.SyncNow(r.Context())
		}
		http.Redirect(w, r, "/admin/items", http.StatusSeeOther)
	})

	mux.HandleFunc("/admin/mesh/syncnow", func(w http.ResponseWriter, r *http.Request) {
		_ = d.Mesh.SyncNow(context.Background())
		http.Redirect(w, r, "/admin/peers", http.StatusSeeOther)
	})
}

func renderLayout(w http.ResponseWriter, _ *http.Request, active string, initial string) {
	_ = tplLayout.Execute(w, map[string]any{
		"Active": active,
		"Init":   initial, // initialer HTMX Swap-Endpunkt
	})
}

/*** Optional: einfache BasicAuth (siehe main.go) ***/
func BasicAuth(user, pass string, next http.Handler) http.Handler {
	if strings.TrimSpace(user) == "" {
		return next // deaktiviert
	}
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		u, p, ok := r.BasicAuth()
		if !ok || u != user || p != pass {
			w.Header().Set("WWW-Authenticate", `Basic realm="admin"`)
			http.Error(w, "unauthorized", http.StatusUnauthorized)
			return
		}
		next.ServeHTTP(w, r)
	})
}