package platform

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

type APIError struct {
	Status  int
	Code    string
	Message string
}

func (e *APIError) Error() string { return e.Message }

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 WriteError(w http.ResponseWriter, err error) {
	var apiErr *APIError
	if errors.As(err, &apiErr) {
		WriteJSON(w, apiErr.Status, map[string]any{"error": map[string]string{"code": apiErr.Code, "message": apiErr.Message}})
		return
	}
	WriteJSON(w, http.StatusInternalServerError, map[string]any{"error": map[string]string{"code": "internal_error", "message": "服务暂时不可用"}})
}

func DecodeJSON(r *http.Request, target any) error {
	decoder := json.NewDecoder(io.LimitReader(r.Body, (1<<20)+1))
	decoder.DisallowUnknownFields()
	if err := decoder.Decode(target); err != nil {
		return &APIError{Status: http.StatusBadRequest, Code: "invalid_request", Message: "请求内容格式不正确"}
	}
	if err := decoder.Decode(&struct{}{}); err != io.EOF {
		return &APIError{Status: http.StatusBadRequest, Code: "invalid_request", Message: "请求内容格式不正确"}
	}
	return nil
}