package handlers

import (
	"encoding/json"
	"net/http"

	"nano-router/config"
	"nano-router/nat"
)

func HandleNATGet(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		fail(w, http.StatusMethodNotAllowed, "method not allowed")
		return
	}

	cfg, err := nat.Load()
	if err != nil {
		fail(w, http.StatusInternalServerError, err.Error())
		return
	}

	ok(w, map[string]interface{}{
		"installed":  nat.IsInstalled(),
		"interfaces": cfg.Interfaces,
	})
}

func HandleNATSave(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		fail(w, http.StatusMethodNotAllowed, "method not allowed")
		return
	}

	var cfg nat.Config
	if err := json.NewDecoder(r.Body).Decode(&cfg); err != nil {
		fail(w, http.StatusBadRequest, "invalid json: "+err.Error())
		return
	}
	if cfg.Interfaces == nil {
		cfg.Interfaces = []string{}
	}

	if !nat.IsInstalled() {
		fail(w, http.StatusServiceUnavailable, "nftables (nft) не установлен — выполните: apk add nftables")
		return
	}

	appCfg, err := config.Load()
	if err != nil {
		fail(w, http.StatusInternalServerError, "load config.yaml: "+err.Error())
		return
	}

	for _, ifaceName := range cfg.Interfaces {
		if appCfg.Interfaces != nil {
			if ic, ok := appCfg.Interfaces[ifaceName]; ok && ic.Type == "wan" {
				fail(w, http.StatusBadRequest, "WAN interface "+ifaceName+" cannot have NAT/Masquerade")
				return
			}
		}
	}

	if err := nat.Save(&cfg); err != nil {
		fail(w, http.StatusInternalServerError, "save: "+err.Error())
		return
	}

	appCfg.NAT.Interfaces = cfg.Interfaces
	if err := config.Save(appCfg); err != nil {
		fail(w, http.StatusInternalServerError, "save config.yaml: "+err.Error())
		return
	}

	if err := applyAllRules(appCfg); err != nil {
		fail(w, http.StatusInternalServerError, "apply: "+err.Error())
		return
	}

	ok(w, map[string]string{"message": "nat applied"})
}