package app

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

func handleSmartdnsRuntime(w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	case http.MethodGet:
		writeJSON(w, http.StatusOK, smartDNSRuntimeSnapshot())
	case http.MethodPost:
		var body SmartDNSRuntimeRequest
		if r.Body != nil {
			defer r.Body.Close()
			if err := json.NewDecoder(io.LimitReader(r.Body, 1<<20)).Decode(&body); err != nil && err != io.EOF {
				http.Error(w, "bad json", http.StatusBadRequest)
				return
			}
		}
		if body.Enabled == nil {
			http.Error(w, "enabled is required", http.StatusBadRequest)
			return
		}

		prev := loadSmartDNSRuntimeState(nil)
		next := prev
		next.Enabled = *body.Enabled
		if err := saveSmartDNSRuntimeState(next); err != nil {
			http.Error(w, "runtime state write error", http.StatusInternalServerError)
			return
		}

		changed, err := applySmartDNSRuntimeConfig(next.Enabled)
		if err != nil {
			_ = saveSmartDNSRuntimeState(prev)
			http.Error(w, "runtime config apply error: "+err.Error(), http.StatusInternalServerError)
			return
		}

		restart := true
		if body.Restart != nil {
			restart = *body.Restart
		}
		restarted := false
		msg := ""
		if restart && smartdnsUnitState() == "active" {
			res := runSmartdnsUnitAction("restart")
			restarted = res.OK
			if !res.OK {
				msg = "runtime config changed, but smartdns restart failed: " + strings.TrimSpace(res.Message)
			}
		}
		if msg == "" {
			msg = fmt.Sprintf("smartdns runtime set: enabled=%t changed=%t restarted=%t", next.Enabled, changed, restarted)
		}
		appendTraceLineTo(smartdnsLogPath, "smartdns", msg)

		resp := smartDNSRuntimeSnapshot()
		resp.Changed = changed
		resp.Restarted = restarted
		resp.Message = msg
		writeJSON(w, http.StatusOK, resp)
	default:
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
	}
}