/*
   Copyright The containerd 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 docker

import (
	"context"
	"crypto/tls"
	"crypto/x509"
	"encoding/json"
	"fmt"
	"io"
	"io/ioutil"
	"net/http"
	"net/http/httptest"
	"strconv"
	"strings"
	"testing"

	"github.com/containerd/containerd/remotes"
	digest "github.com/opencontainers/go-digest"
	specs "github.com/opencontainers/image-spec/specs-go"
	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
	"github.com/pkg/errors"
)

func TestHTTPResolver(t *testing.T) {
	s := func(h http.Handler) (string, ResolverOptions, func()) {
		s := httptest.NewServer(h)

		options := ResolverOptions{
			PlainHTTP: true,
		}
		base := s.URL[7:] // strip "http://"
		return base, options, s.Close
	}

	runBasicTest(t, "testname", s)
}

func TestHTTPSResolver(t *testing.T) {
	runBasicTest(t, "testname", tlsServer)
}

func TestBasicResolver(t *testing.T) {
	basicAuth := func(h http.Handler) (string, ResolverOptions, func()) {
		// Wrap with basic auth
		wrapped := http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
			username, password, ok := r.BasicAuth()
			if !ok || username != "user1" || password != "password1" {
				rw.Header().Set("WWW-Authenticate", "Basic realm=localhost")
				rw.WriteHeader(http.StatusUnauthorized)
				return
			}
			h.ServeHTTP(rw, r)
		})

		base, options, close := tlsServer(wrapped)
		options.Credentials = func(string) (string, string, error) {
			return "user1", "password1", nil
		}
		return base, options, close
	}
	runBasicTest(t, "testname", basicAuth)
}

func TestAnonymousTokenResolver(t *testing.T) {
	th := http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodGet {
			rw.WriteHeader(http.StatusMethodNotAllowed)
			return
		}
		rw.Header().Set("Content-Type", "application/json")
		rw.WriteHeader(http.StatusOK)
		rw.Write([]byte(`{"access_token":"perfectlyvalidopaquetoken"}`))
	})

	runBasicTest(t, "testname", withTokenServer(th, nil))
}

func TestBasicAuthTokenResolver(t *testing.T) {
	th := http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodGet {
			rw.WriteHeader(http.StatusMethodNotAllowed)
			return
		}
		rw.Header().Set("Content-Type", "application/json")
		rw.WriteHeader(http.StatusOK)
		username, password, ok := r.BasicAuth()
		if !ok || username != "user1" || password != "password1" {
			rw.Write([]byte(`{"access_token":"insufficientscope"}`))
		} else {
			rw.Write([]byte(`{"access_token":"perfectlyvalidopaquetoken"}`))
		}
	})
	creds := func(string) (string, string, error) {
		return "user1", "password1", nil
	}

	runBasicTest(t, "testname", withTokenServer(th, creds))
}

func TestRefreshTokenResolver(t *testing.T) {
	th := http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			rw.WriteHeader(http.StatusMethodNotAllowed)
			return
		}
		rw.Header().Set("Content-Type", "application/json")
		rw.WriteHeader(http.StatusOK)

		r.ParseForm()
		if r.PostForm.Get("grant_type") != "refresh_token" || r.PostForm.Get("refresh_token") != "somerefreshtoken" {
			rw.Write([]byte(`{"access_token":"insufficientscope"}`))
		} else {
			rw.Write([]byte(`{"access_token":"perfectlyvalidopaquetoken"}`))
		}
	})
	creds := func(string) (string, string, error) {
		return "", "somerefreshtoken", nil
	}

	runBasicTest(t, "testname", withTokenServer(th, creds))
}

func TestPostBasicAuthTokenResolver(t *testing.T) {
	th := http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			rw.WriteHeader(http.StatusMethodNotAllowed)
			return
		}
		rw.Header().Set("Content-Type", "application/json")
		rw.WriteHeader(http.StatusOK)

		r.ParseForm()
		if r.PostForm.Get("grant_type") != "password" || r.PostForm.Get("username") != "user1" || r.PostForm.Get("password") != "password1" {
			rw.Write([]byte(`{"access_token":"insufficientscope"}`))
		} else {
			rw.Write([]byte(`{"access_token":"perfectlyvalidopaquetoken"}`))
		}
	})
	creds := func(string) (string, string, error) {
		return "user1", "password1", nil
	}

	runBasicTest(t, "testname", withTokenServer(th, creds))
}

func TestBadTokenResolver(t *testing.T) {
	th := http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			rw.WriteHeader(http.StatusMethodNotAllowed)
			return
		}
		rw.Header().Set("Content-Type", "application/json")
		rw.WriteHeader(http.StatusOK)
		rw.Write([]byte(`{"access_token":"insufficientscope"}`))
	})
	creds := func(string) (string, string, error) {
		return "", "somerefreshtoken", nil
	}

	ctx := context.Background()
	h := newContent(ocispec.MediaTypeImageManifest, []byte("not anything parse-able"))

	base, ro, close := withTokenServer(th, creds)(logHandler{t, h})
	defer close()

	resolver := NewResolver(ro)
	image := fmt.Sprintf("%s/doesntmatter:sometatg", base)

	_, _, err := resolver.Resolve(ctx, image)
	if err == nil {
		t.Fatal("Expected error getting token with inssufficient scope")
	}
	if errors.Cause(err) != ErrInvalidAuthorization {
		t.Fatal(err)
	}
}

func withTokenServer(th http.Handler, creds func(string) (string, string, error)) func(h http.Handler) (string, ResolverOptions, func()) {
	return func(h http.Handler) (string, ResolverOptions, func()) {
		s := httptest.NewUnstartedServer(th)
		s.StartTLS()

		cert, _ := x509.ParseCertificate(s.TLS.Certificates[0].Certificate[0])
		tokenBase := s.URL + "/token"

		// Wrap with token auth
		wrapped := http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
			auth := strings.ToLower(r.Header.Get("Authorization"))
			if auth != "bearer perfectlyvalidopaquetoken" {
				authHeader := fmt.Sprintf("Bearer realm=%q,service=registry,scope=\"repository:testname:pull,pull\"", tokenBase)
				if strings.HasPrefix(auth, "bearer ") {
					authHeader = authHeader + ",error=" + auth[7:]
				}
				rw.Header().Set("WWW-Authenticate", authHeader)
				rw.WriteHeader(http.StatusUnauthorized)
				return
			}
			h.ServeHTTP(rw, r)
		})

		base, options, close := tlsServer(wrapped)
		options.Credentials = creds
		options.Client.Transport.(*http.Transport).TLSClientConfig.RootCAs.AddCert(cert)
		return base, options, func() {
			s.Close()
			close()
		}
	}
}

func tlsServer(h http.Handler) (string, ResolverOptions, func()) {
	s := httptest.NewUnstartedServer(h)
	s.StartTLS()

	capool := x509.NewCertPool()
	cert, _ := x509.ParseCertificate(s.TLS.Certificates[0].Certificate[0])
	capool.AddCert(cert)

	options := ResolverOptions{
		Client: &http.Client{
			Transport: &http.Transport{
				TLSClientConfig: &tls.Config{
					RootCAs: capool,
				},
			},
		},
	}
	base := s.URL[8:] // strip "https://"
	return base, options, s.Close
}

type logHandler struct {
	t       *testing.T
	handler http.Handler
}

func (h logHandler) ServeHTTP(rw http.ResponseWriter, r *http.Request) {
	h.handler.ServeHTTP(rw, r)
}

func runBasicTest(t *testing.T, name string, sf func(h http.Handler) (string, ResolverOptions, func())) {
	var (
		ctx = context.Background()
		tag = "latest"
		r   = http.NewServeMux()
	)

	m := newManifest(
		newContent(ocispec.MediaTypeImageConfig, []byte("1")),
		newContent(ocispec.MediaTypeImageLayerGzip, []byte("2")),
	)
	mc := newContent(ocispec.MediaTypeImageManifest, m.OCIManifest())
	m.RegisterHandler(r, name)
	r.Handle(fmt.Sprintf("/v2/%s/manifests/%s", name, tag), mc)
	r.Handle(fmt.Sprintf("/v2/%s/manifests/%s", name, mc.Digest()), mc)

	base, ro, close := sf(logHandler{t, r})
	defer close()

	resolver := NewResolver(ro)
	image := fmt.Sprintf("%s/%s:%s", base, name, tag)

	_, d, err := resolver.Resolve(ctx, image)
	if err != nil {
		t.Fatal(err)
	}
	f, err := resolver.Fetcher(ctx, image)
	if err != nil {
		t.Fatal(err)
	}

	refs, err := testocimanifest(ctx, f, d)
	if err != nil {
		t.Fatal(err)
	}

	if len(refs) != 2 {
		t.Fatalf("Unexpected number of references: %d, expected 2", len(refs))
	}

	for _, ref := range refs {
		if err := testFetch(ctx, f, ref); err != nil {
			t.Fatal(err)
		}
	}
}

func testFetch(ctx context.Context, f remotes.Fetcher, desc ocispec.Descriptor) error {
	r, err := f.Fetch(ctx, desc)
	if err != nil {
		return err
	}
	dgstr := desc.Digest.Algorithm().Digester()
	io.Copy(dgstr.Hash(), r)
	if dgstr.Digest() != desc.Digest {
		return errors.Errorf("content mismatch: %s != %s", dgstr.Digest(), desc.Digest)
	}

	return nil
}

func testocimanifest(ctx context.Context, f remotes.Fetcher, desc ocispec.Descriptor) ([]ocispec.Descriptor, error) {
	r, err := f.Fetch(ctx, desc)
	if err != nil {
		return nil, errors.Wrapf(err, "failed to fetch %s", desc.Digest)
	}
	p, err := ioutil.ReadAll(r)
	if err != nil {
		return nil, err
	}
	if dgst := desc.Digest.Algorithm().FromBytes(p); dgst != desc.Digest {
		return nil, errors.Errorf("digest mismatch: %s != %s", dgst, desc.Digest)
	}

	var manifest ocispec.Manifest
	if err := json.Unmarshal(p, &manifest); err != nil {
		return nil, err
	}

	var descs []ocispec.Descriptor

	descs = append(descs, manifest.Config)
	descs = append(descs, manifest.Layers...)

	return descs, nil
}

type testContent struct {
	mediaType string
	content   []byte
}

func newContent(mediaType string, b []byte) testContent {
	return testContent{
		mediaType: mediaType,
		content:   b,
	}
}

func (tc testContent) Descriptor() ocispec.Descriptor {
	return ocispec.Descriptor{
		MediaType: tc.mediaType,
		Digest:    digest.FromBytes(tc.content),
		Size:      int64(len(tc.content)),
	}
}

func (tc testContent) Digest() digest.Digest {
	return digest.FromBytes(tc.content)
}

func (tc testContent) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	w.Header().Add("Content-Type", tc.mediaType)
	w.Header().Add("Content-Length", strconv.Itoa(len(tc.content)))
	w.Header().Add("Docker-Content-Digest", tc.Digest().String())
	w.WriteHeader(http.StatusOK)
	w.Write(tc.content)
}

type testManifest struct {
	config     testContent
	references []testContent
}

func newManifest(config testContent, refs ...testContent) testManifest {
	return testManifest{
		config:     config,
		references: refs,
	}
}

func (m testManifest) OCIManifest() []byte {
	manifest := ocispec.Manifest{
		Versioned: specs.Versioned{
			SchemaVersion: 1,
		},
		Config: m.config.Descriptor(),
		Layers: make([]ocispec.Descriptor, len(m.references)),
	}
	for i, c := range append(m.references) {
		manifest.Layers[i] = c.Descriptor()
	}
	b, _ := json.Marshal(manifest)
	return b
}

func (m testManifest) RegisterHandler(r *http.ServeMux, name string) {
	for _, c := range append(m.references, m.config) {
		r.Handle(fmt.Sprintf("/v2/%s/blobs/%s", name, c.Digest()), c)
	}
}
