// internal/adminhttp/http.go 提供 Admin API 处理器共用的 JSON、路径片段和来源 IP 辅助方法。

package adminhttp

import (
	"encoding/json"
	"errors"
	"net"
	"net/http"
	"net/url"
	"strings"
)

func DecodeJSONRequest(w http.ResponseWriter, r *http.Request, dst any) bool {
	defer r.Body.Close()
	decoder := json.NewDecoder(r.Body)
	decoder.UseNumber()
	if err := decoder.Decode(dst); err != nil {
		WriteAPIError(w, http.StatusBadRequest, "invalid JSON: "+err.Error())
		return false
	}
	return true
}

func WriteJSON(w http.ResponseWriter, status int, value any) {
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	w.WriteHeader(status)
	_ = json.NewEncoder(w).Encode(value)
}

func WriteAPIError(w http.ResponseWriter, status int, message string) {
	WriteJSON(w, status, map[string]any{
		"error": message,
	})
}

func PathSegment(raw string) (string, error) {
	if raw == "" || strings.Contains(raw, "/") {
		return "", errors.New("invalid path segment")
	}
	value, err := url.PathUnescape(raw)
	if err != nil {
		return "", err
	}
	if value == "" || strings.Contains(value, "/") {
		return "", errors.New("invalid path segment")
	}
	return value, nil
}

func RequestSourceIP(r *http.Request) string {
	host, _, err := net.SplitHostPort(r.RemoteAddr)
	if err == nil {
		return host
	}
	if r.RemoteAddr != "" {
		return r.RemoteAddr
	}
	return "unknown"
}