/*
Copyright 2016 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package apiserver

import (
	"fmt"
	"net/http"
	"net/http/httptest"
	"reflect"
	"sync"
	"testing"

	"k8s.io/kubernetes/pkg/api"
	authenticationapi "k8s.io/kubernetes/pkg/apis/authentication"
	"k8s.io/kubernetes/pkg/auth/authorizer"
	"k8s.io/kubernetes/pkg/auth/user"
)

type impersonateAuthorizer struct{}

func (impersonateAuthorizer) Authorize(a authorizer.Attributes) (authorized bool, reason string, err error) {
	user := a.GetUser()

	switch {
	case user.GetName() == "system:admin":
		return true, "", nil

	case user.GetName() == "tester":
		return false, "", fmt.Errorf("works on my machine")

	case user.GetName() == "deny-me":
		return false, "denied", nil
	}

	if len(user.GetGroups()) > 0 && user.GetGroups()[0] == "wheel" && a.GetVerb() == "impersonate" && a.GetResource() == "users" {
		return true, "", nil
	}

	if len(user.GetGroups()) > 0 && user.GetGroups()[0] == "sa-impersonater" && a.GetVerb() == "impersonate" && a.GetResource() == "serviceaccounts" {
		return true, "", nil
	}

	if len(user.GetGroups()) > 0 && user.GetGroups()[0] == "regular-impersonater" && a.GetVerb() == "impersonate" && a.GetResource() == "users" {
		return true, "", nil
	}

	if len(user.GetGroups()) > 1 && user.GetGroups()[1] == "group-impersonater" && a.GetVerb() == "impersonate" && a.GetResource() == "groups" {
		return true, "", nil
	}

	return false, "deny by default", nil
}

func TestImpersonationFilter(t *testing.T) {
	testCases := []struct {
		name                string
		user                user.Info
		impersonationUser   string
		impersonationGroups []string
		expectedUser        user.Info
		expectedCode        int
	}{
		{
			name: "not-impersonating",
			user: &user.DefaultInfo{
				Name: "tester",
			},
			expectedUser: &user.DefaultInfo{
				Name: "tester",
			},
			expectedCode: http.StatusOK,
		},
		{
			name: "impersonating-error",
			user: &user.DefaultInfo{
				Name: "tester",
			},
			impersonationUser: "anyone",
			expectedUser: &user.DefaultInfo{
				Name: "tester",
			},
			expectedCode: http.StatusForbidden,
		},
		{
			name: "impersonating-group-without-user",
			user: &user.DefaultInfo{
				Name: "tester",
			},
			impersonationGroups: []string{"some-group"},
			expectedUser: &user.DefaultInfo{
				Name: "tester",
			},
			expectedCode: http.StatusForbidden,
		},
		{
			name: "disallowed-group",
			user: &user.DefaultInfo{
				Name:   "dev",
				Groups: []string{"wheel"},
			},
			impersonationUser:   "system:admin",
			impersonationGroups: []string{"some-group"},
			expectedUser: &user.DefaultInfo{
				Name:   "dev",
				Groups: []string{"wheel"},
			},
			expectedCode: http.StatusForbidden,
		},
		{
			name: "allowed-group",
			user: &user.DefaultInfo{
				Name:   "dev",
				Groups: []string{"wheel", "group-impersonater"},
			},
			impersonationUser:   "system:admin",
			impersonationGroups: []string{"some-group"},
			expectedUser: &user.DefaultInfo{
				Name:   "system:admin",
				Groups: []string{"some-group"},
				Extra:  map[string][]string{},
			},
			expectedCode: http.StatusOK,
		},
		{
			name: "allowed-users-impersonation",
			user: &user.DefaultInfo{
				Name:   "dev",
				Groups: []string{"regular-impersonater"},
			},
			impersonationUser: "tester",
			expectedUser: &user.DefaultInfo{
				Name:   "tester",
				Groups: []string{},
				Extra:  map[string][]string{},
			},
			expectedCode: http.StatusOK,
		},
		{
			name: "disallowed-impersonating",
			user: &user.DefaultInfo{
				Name:   "dev",
				Groups: []string{"sa-impersonater"},
			},
			impersonationUser: "tester",
			expectedUser: &user.DefaultInfo{
				Name:   "dev",
				Groups: []string{"sa-impersonater"},
			},
			expectedCode: http.StatusForbidden,
		},
		{
			name: "allowed-sa-impersonating",
			user: &user.DefaultInfo{
				Name:   "dev",
				Groups: []string{"sa-impersonater"},
				Extra:  map[string][]string{},
			},
			impersonationUser: "system:serviceaccount:foo:default",
			expectedUser: &user.DefaultInfo{
				Name:   "system:serviceaccount:foo:default",
				Groups: []string{"system:serviceaccounts", "system:serviceaccounts:foo"},
				Extra:  map[string][]string{},
			},
			expectedCode: http.StatusOK,
		},
	}

	requestContextMapper = api.NewRequestContextMapper()
	var ctx api.Context
	var actualUser user.Info
	var lock sync.Mutex

	doNothingHandler := http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
		currentCtx, _ := requestContextMapper.Get(req)
		user, exists := api.UserFrom(currentCtx)
		if !exists {
			actualUser = nil
			return
		}

		actualUser = user
	})
	handler := func(delegate http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
			defer func() {
				if r := recover(); r != nil {
					t.Errorf("Recovered %v", r)
				}
			}()
			lock.Lock()
			defer lock.Unlock()
			requestContextMapper.Update(req, ctx)
			currentCtx, _ := requestContextMapper.Get(req)

			user, exists := api.UserFrom(currentCtx)
			if !exists {
				actualUser = nil
				return
			} else {
				actualUser = user
			}

			delegate.ServeHTTP(w, req)
		})
	}(WithImpersonation(doNothingHandler, requestContextMapper, impersonateAuthorizer{}))
	handler, _ = api.NewRequestContextFilter(requestContextMapper, handler)

	server := httptest.NewServer(handler)
	defer server.Close()

	for _, tc := range testCases {
		func() {
			lock.Lock()
			defer lock.Unlock()
			ctx = api.WithUser(api.NewContext(), tc.user)
		}()

		req, err := http.NewRequest("GET", server.URL, nil)
		if err != nil {
			t.Errorf("%s: unexpected error: %v", tc.name, err)
			continue
		}
		req.Header.Add(authenticationapi.ImpersonateUserHeader, tc.impersonationUser)
		for _, group := range tc.impersonationGroups {
			req.Header.Add(authenticationapi.ImpersonateGroupHeader, group)
		}
		resp, err := http.DefaultClient.Do(req)
		if err != nil {
			t.Errorf("%s: unexpected error: %v", tc.name, err)
			continue
		}
		if resp.StatusCode != tc.expectedCode {
			t.Errorf("%s: expected %v, actual %v", tc.name, tc.expectedCode, resp.StatusCode)
			continue
		}

		if !reflect.DeepEqual(actualUser, tc.expectedUser) {
			t.Errorf("%s: expected %#v, actual %#v", tc.name, tc.expectedUser, actualUser)
			continue
		}
	}
}