package server

import (
	"log"
	"net/http"
	"net/url"
	"strconv"
	"strings"
)

func (s *Server) handleForwardsPage(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	a, err := s.db.GetAgent(id)
	if err != nil || a == nil {
		http.NotFound(w, r)
		return
	}
	rules, _ := s.db.ListForwardRulesByAgent(id)
	errMsg := map[string]string{
		"busy":   "Этот порт хоста уже занят другим правилом.",
		"tunnel": "Этот порт занят прямым туннелем панели (см. Настройки).",
		"port":   "Некорректный номер порта.",
		"listen": "Не удалось занять порт на хосте (возможно, уже используется).",
		"db":     "Ошибка базы данных.",
	}[r.URL.Query().Get("err")]
	s.render(w, "forwards.html", map[string]any{
		"Agent":      a,
		"Rules":      rules,
		"CSRF":       csrfToken(r),
		"Error":      errMsg,
		"TunnelPort": s.TunnelPort(),
		"PanelPort":  panelPort(s.db.HostAddress()),
	})
}

// panelPort is the port of the panel URL agents dial, for the mode hints.
func panelPort(host string) string {
	u, err := url.Parse(host)
	if err != nil {
		return ""
	}
	if p := u.Port(); p != "" {
		return p
	}
	if u.Scheme == "http" {
		return "80"
	}
	return "443"
}

// POST /agents/{id}/forwards/add
func (s *Server) handleForwardAdd(w http.ResponseWriter, r *http.Request) {
	if !checkCSRF(r) {
		http.Error(w, "bad csrf", http.StatusForbidden)
		return
	}
	id := r.PathValue("id")
	a, err := s.db.GetAgent(id)
	if err != nil || a == nil {
		http.NotFound(w, r)
		return
	}
	clientPort, _ := strconv.Atoi(strings.TrimSpace(r.FormValue("client_port")))
	hostPort, _ := strconv.Atoi(strings.TrimSpace(r.FormValue("host_port")))
	listenAddr := strings.TrimSpace(r.FormValue("listen_addr"))
	if listenAddr == "" {
		listenAddr = "0.0.0.0"
	}
	protoKind := strings.TrimSpace(r.FormValue("proto"))
	switch protoKind {
	case "http", "tcp", "udp":
	default:
		protoKind = "http"
	}
	if clientPort < 1 || clientPort > 65535 || hostPort < 1 || hostPort > 65535 {
		http.Redirect(w, r, "/agents/"+id+"/forwards?err=port", http.StatusSeeOther)
		return
	}
	// Reject a host port already bound by another forward rule or the tunnel.
	if hostPort == s.TunnelPort() {
		http.Redirect(w, r, "/agents/"+id+"/forwards?err=tunnel", http.StatusSeeOther)
		return
	}
	if s.db.HostPortUsed(hostPort) {
		http.Redirect(w, r, "/agents/"+id+"/forwards?err=busy", http.StatusSeeOther)
		return
	}
	rule := ForwardRule{AgentID: id, ClientPort: clientPort, HostPort: hostPort, ListenAddr: listenAddr, Proto: protoKind}
	ruleID, err := s.db.CreateForwardRule(rule)
	if err != nil {
		http.Redirect(w, r, "/agents/"+id+"/forwards?err=db", http.StatusSeeOther)
		return
	}
	rule.ID = ruleID
	if err := s.fwd.open(rule); err != nil {
		// Roll back the rule if the port can't be bound.
		_ = s.db.DeleteForwardRule(ruleID)
		log.Printf("forward open %s:%d: %v", listenAddr, hostPort, err)
		http.Redirect(w, r, "/agents/"+id+"/forwards?err=listen", http.StatusSeeOther)
		return
	}
	// Open the port in ufw too (if integration is enabled and ufw is active).
	s.ufw.allowForward(rule)
	http.Redirect(w, r, "/agents/"+id+"/forwards", http.StatusSeeOther)
}

// POST /forwards/{rid}/delete
func (s *Server) handleForwardDelete(w http.ResponseWriter, r *http.Request) {
	if !checkCSRF(r) {
		http.Error(w, "bad csrf", http.StatusForbidden)
		return
	}
	rid, _ := strconv.ParseInt(r.PathValue("rid"), 10, 64)
	rule, _ := s.db.GetForwardRule(rid)
	s.removeForward(rid)
	dest := "/"
	if rule != nil {
		dest = "/agents/" + rule.AgentID + "/forwards"
	}
	http.Redirect(w, r, dest, http.StatusSeeOther)
}

// removeForward closes a forward rule's listener and deletes the rule, along
// with the ufw rule bound to it (the shared tunnel port stays while another
// direct forward needs it).
func (s *Server) removeForward(rid int64) {
	s.fwd.close(rid)
	_ = s.db.DeleteForwardRule(rid)
	s.ufw.revokeForRule(rid)
}