package app

import (
	"encoding/json"
	"io"
	"net/http"
	"strings"
)

// ---------------------------------------------------------------------
// EN: `handleDNSStatus` is an HTTP handler for dns status.
// RU: `handleDNSStatus` - HTTP-обработчик для dns status.
// ---------------------------------------------------------------------
func handleDNSStatus(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
		return
	}
	mode := loadDNSMode()
	writeJSON(w, http.StatusOK, makeDNSStatusResponse(mode))
}

// ---------------------------------------------------------------------
// EN: `handleDNSModeSet` is an HTTP handler for dns mode set.
// RU: `handleDNSModeSet` - HTTP-обработчик для dns mode set.
// ---------------------------------------------------------------------
func handleDNSModeSet(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
		return
	}

	var req DNSModeRequest
	if r.Body != nil {
		defer r.Body.Close()
		if err := json.NewDecoder(io.LimitReader(r.Body, 1<<20)).Decode(&req); err != nil && err != io.EOF {
			http.Error(w, "bad json", http.StatusBadRequest)
			return
		}
	}

	mode := loadDNSMode()
	mode.Mode = normalizeDNSResolverMode(req.Mode, req.ViaSmartDNS)
	mode.ViaSmartDNS = mode.Mode != DNSModeDirect
	if strings.TrimSpace(req.SmartDNSAddr) != "" {
		mode.SmartDNSAddr = req.SmartDNSAddr
	}
	if err := saveDNSMode(mode); err != nil {
		http.Error(w, "write error", http.StatusInternalServerError)
		return
	}

	mode = loadDNSMode()
	writeJSON(w, http.StatusOK, makeDNSStatusResponse(mode))
}

func makeDNSStatusResponse(mode DNSMode) DNSStatusResponse {
	rt := smartDNSRuntimeSnapshot()
	resp := DNSStatusResponse{
		ViaSmartDNS:    mode.ViaSmartDNS,
		SmartDNSAddr:   mode.SmartDNSAddr,
		Mode:           mode.Mode,
		UnitState:      smartdnsUnitState(),
		RuntimeNftset:  rt.Enabled,
		WildcardSource: rt.WildcardSource,
		RuntimeCfgPath: rt.ConfigPath,
	}
	if rt.Message != "" {
		resp.RuntimeCfgError = rt.Message
	}
	return resp
}