// Package httpx holds the tiny JSON helpers shared by the public and admin APIs.
package httpx

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

type ErrorResponse struct {
	Error string `json:"error"`
}

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

func OK(w http.ResponseWriter, v any)      { WriteJSON(w, http.StatusOK, v) }
func Created(w http.ResponseWriter, v any) { WriteJSON(w, http.StatusCreated, v) }

func Error(w http.ResponseWriter, status int, msg string) {
	WriteJSON(w, status, ErrorResponse{Error: msg})
}

func BadRequest(w http.ResponseWriter, msg string) { Error(w, http.StatusBadRequest, msg) }
func NotFound(w http.ResponseWriter)               { Error(w, http.StatusNotFound, "not found") }
func Unauthorized(w http.ResponseWriter)           { Error(w, http.StatusUnauthorized, "unauthorized") }
func ServerError(w http.ResponseWriter, err error) {
	Error(w, http.StatusInternalServerError, err.Error())
}

func Decode(r *http.Request, dst any) error {
	body, err := io.ReadAll(io.LimitReader(r.Body, 8<<20))
	if err != nil {
		return err
	}
	if len(body) == 0 {
		return io.EOF
	}
	return json.Unmarshal(body, dst)
}

func QueryInt(r *http.Request, key string, def int) int {
	s := r.URL.Query().Get(key)
	if s == "" {
		return def
	}
	n, err := strconv.Atoi(s)
	if err != nil || n < 0 {
		return def
	}
	return n
}

func QueryString(r *http.Request, key string) string {
	return r.URL.Query().Get(key)
}