package dependencyproxy

import (
	"encoding/base64"
	"fmt"
	"io"
	"net/http"
	"net/http/httptest"
	"strconv"
	"strings"
	"testing"

	"github.com/stretchr/testify/require"

	"gitlab.com/gitlab-org/gitlab/workhorse/internal/api"
	"gitlab.com/gitlab-org/gitlab/workhorse/internal/testhelper"
	"gitlab.com/gitlab-org/gitlab/workhorse/internal/upload"
)

type fakeUploadHandler struct {
	request *http.Request
	body    []byte
	handler func(w http.ResponseWriter, r *http.Request)
}

func (f *fakeUploadHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	f.request = r

	f.body, _ = io.ReadAll(r.Body)

	f.handler(w, r)
}

type errWriter struct{ writes int }

func (w *errWriter) Header() http.Header { return make(http.Header) }
func (w *errWriter) WriteHeader(h int)   {}

// First call of Write function succeeds while all the subsequent ones fail
func (w *errWriter) Write(p []byte) (int, error) {
	if w.writes > 0 {
		return 0, fmt.Errorf("client error")
	}

	w.writes++

	return len(p), nil
}

type fakePreAuthHandler struct{}

func (f *fakePreAuthHandler) PreAuthorizeHandler(handler api.HandleFunc, _ string) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		handler(w, r, &api.Response{TempPath: "../../testdata/scratch"})
	})
}

func TestInject(t *testing.T) {
	contentLength := 32768 + 1
	content := strings.Repeat("p", contentLength)

	testCases := []struct {
		desc                string
		responseWriter      http.ResponseWriter
		contentLength       int
		handlerMustBeCalled bool
	}{
		{
			desc:                "the uploading successfully finalized",
			responseWriter:      httptest.NewRecorder(),
			contentLength:       contentLength,
			handlerMustBeCalled: true,
		}, {
			desc:                "a user failed to receive the response",
			responseWriter:      &errWriter{},
			contentLength:       contentLength,
			handlerMustBeCalled: false,
		}, {
			desc:                "the origin resource server returns partial response",
			responseWriter:      httptest.NewRecorder(),
			contentLength:       contentLength + 1,
			handlerMustBeCalled: false,
		},
	}
	testhelper.ConfigureSecret()

	for _, tc := range testCases {
		originResourceServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			w.Header().Set("Content-Length", strconv.Itoa(tc.contentLength))
			w.Write([]byte(content))
		}))
		defer originResourceServer.Close()

		// RequestBody expects http.Handler as its second param, we can create a stub function and verify that
		// it's only called for successful requests
		handlerIsCalled := false
		handlerFunc := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { handlerIsCalled = true })

		bodyUploader := upload.RequestBody(&fakePreAuthHandler{}, handlerFunc, &upload.DefaultPreparer{})

		injector := NewInjector()
		injector.SetUploadHandler(bodyUploader)

		r := httptest.NewRequest("GET", "/target", nil)
		sendData := base64.StdEncoding.EncodeToString([]byte(`{"Token": "token", "Url": "` + originResourceServer.URL + `/url"}`))

		injector.Inject(tc.responseWriter, r, sendData)

		require.Equal(t, tc.handlerMustBeCalled, handlerIsCalled, "a partial file must not be saved")
	}
}

func TestSuccessfullRequest(t *testing.T) {
	content := []byte("result")
	contentLength := strconv.Itoa(len(content))
	contentType := "foo"
	dockerContentDigest := "sha256:asdf1234"
	overriddenHeader := "originResourceServer"
	originResourceServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Length", contentLength)
		w.Header().Set("Content-Type", contentType)
		w.Header().Set("Docker-Content-Digest", dockerContentDigest)
		w.Header().Set("Overridden-Header", overriddenHeader)
		w.Write(content)
	}))

	uploadHandler := &fakeUploadHandler{
		handler: func(w http.ResponseWriter, r *http.Request) {
			w.WriteHeader(200)
		},
	}

	injector := NewInjector()
	injector.SetUploadHandler(uploadHandler)

	response := makeRequest(injector, `{"Token": "token", "Url": "`+originResourceServer.URL+`/url"}`)

	require.Equal(t, "/target/upload", uploadHandler.request.URL.Path)
	require.Equal(t, int64(6), uploadHandler.request.ContentLength)
	require.Equal(t, contentType, uploadHandler.request.Header.Get("Workhorse-Proxy-Content-Type"))
	require.Equal(t, dockerContentDigest, uploadHandler.request.Header.Get("Docker-Content-Digest"))
	require.Equal(t, overriddenHeader, uploadHandler.request.Header.Get("Overridden-Header"))

	require.Equal(t, content, uploadHandler.body)

	require.Equal(t, 200, response.Code)
	require.Equal(t, string(content), response.Body.String())
	require.Equal(t, contentLength, response.Header().Get("Content-Length"))
	require.Equal(t, dockerContentDigest, response.Header().Get("Docker-Content-Digest"))
}

func TestIncorrectSendData(t *testing.T) {
	response := makeRequest(NewInjector(), "")

	require.Equal(t, 500, response.Code)
	require.Equal(t, "Internal server error\n", response.Body.String())
}

func TestIncorrectSendDataUrl(t *testing.T) {
	response := makeRequest(NewInjector(), `{"Token": "token", "Url": "url"}`)

	require.Equal(t, 500, response.Code)
	require.Equal(t, "Internal server error\n", response.Body.String())
}

func TestFailedOriginServer(t *testing.T) {
	originResourceServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(404)
		w.Write([]byte("Not found"))
	}))

	uploadHandler := &fakeUploadHandler{
		handler: func(w http.ResponseWriter, r *http.Request) {
			require.FailNow(t, "the error response must not be uploaded")
		},
	}

	injector := NewInjector()
	injector.SetUploadHandler(uploadHandler)

	response := makeRequest(injector, `{"Token": "token", "Url": "`+originResourceServer.URL+`/url"}`)

	require.Equal(t, 404, response.Code)
	require.Equal(t, "Not found", response.Body.String())
}

func makeRequest(injector *Injector, data string) *httptest.ResponseRecorder {
	w := httptest.NewRecorder()
	r := httptest.NewRequest("GET", "/target", nil)
	r.Header.Set("Overridden-Header", "request")

	sendData := base64.StdEncoding.EncodeToString([]byte(data))
	injector.Inject(w, r, sendData)

	return w
}