package utils

import (
	"bytes"
	"encoding/json"
	"fmt"
	"net/http"

	admissionv1 "k8s.io/api/admission/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/types"
)

func ParseRequest(req http.Request) (*admissionv1.AdmissionReview, error) {
	if req.Header.Get("Content-Type") != "application/json" {
		return nil, fmt.Errorf("http Content-Type: %q should be %q",
			req.Header.Get("Content-Type"), "application/json")
	}

	bodybuf := new(bytes.Buffer)
	_, err := bodybuf.ReadFrom(req.Body)
	if err != nil {
		return nil, err
	}

	body := bodybuf.Bytes()
	if len(body) == 0 {
		return nil, fmt.Errorf("admission request body is empty")
	}

	var admissionReview admissionv1.AdmissionReview
	if err := json.Unmarshal(body, &admissionReview); err != nil {
		return nil, fmt.Errorf("could not parse admission review request: %v", err)
	}

	if admissionReview.Request == nil {
		return nil, fmt.Errorf("admission review can't be used: Request field is nil")
	}

	return &admissionReview, nil
}

// ReviewResponse builds an an admission
func ReviewResponse(uid types.UID, allowed bool, httpCode int32,
	reason string) *admissionv1.AdmissionReview {
	return &admissionv1.AdmissionReview{
		TypeMeta: metav1.TypeMeta{
			Kind:       "AdmissionReview",
			APIVersion: "admission.k8s.io/v1",
		},
		Response: &admissionv1.AdmissionResponse{
			UID:     uid,
			Allowed: allowed,
			Result: &metav1.Status{
				Code:    httpCode,
				Message: reason,
			},
		},
	}
}

// PatchReviewResponse builds an admission review with given json patch
func PatchReviewResponse(uid types.UID, patch []byte) (*admissionv1.AdmissionReview, error) {
	patchType := admissionv1.PatchTypeJSONPatch

	return &admissionv1.AdmissionReview{
		TypeMeta: metav1.TypeMeta{
			Kind:       "AdmissionReview",
			APIVersion: "admission.k8s.io/v1",
		},
		Response: &admissionv1.AdmissionResponse{
			UID:       uid,
			Allowed:   true,
			PatchType: &patchType,
			Patch:     patch,
		},
	}, nil
}