package httpserver_test

import (
	"errors"
	"html/template"
	"io/ioutil"
	"net/http"
	"net/http/httptest"
	"path/filepath"
	"testing"

	"git.netflux.io/rob/elon-eats-my-tweets/config"
	"git.netflux.io/rob/elon-eats-my-tweets/generated/mocks"
	"git.netflux.io/rob/elon-eats-my-tweets/generated/store"
	"git.netflux.io/rob/elon-eats-my-tweets/httpserver"
	"git.netflux.io/rob/elon-eats-my-tweets/twitter"
	"github.com/gorilla/sessions"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/mock"
	"github.com/stretchr/testify/require"
	"go.uber.org/zap"
)

var templates = template.Must(template.ParseGlob(filepath.Join("..", "public", "views", "*.html")))

// mockTokenGenerator implements httpserver.TokenGenerator.
type mockTokenGenerator struct {
	i      int
	tokens []string
}

func (g *mockTokenGenerator) GenerateToken(_ int) string {
	i := g.i
	if len(g.tokens) <= i {
		return ""
	}
	g.i++
	return g.tokens[i]
}

func TestGetIndex(t *testing.T) {
	req := httptest.NewRequest(http.MethodGet, "/", nil)
	rec := httptest.NewRecorder()

	handler := httpserver.NewHandler(
		config.Config{},
		templates,
		&mocks.Store{},
		func(*http.Client) httpserver.TwitterAPIClient { return &mocks.TwitterAPIClient{} },
		&mocks.SessionStore{},
		&mockTokenGenerator{},
		zap.NewNop(),
	)

	handler.ServeHTTP(rec, req)
	res := rec.Result()
	defer res.Body.Close()
	body, err := ioutil.ReadAll(res.Body)
	require.NoError(t, err)

	assert.Equal(t, http.StatusOK, res.StatusCode)
	assert.Contains(t, string(body), "Sign in with Twitter")
}

func TestLogin(t *testing.T) {
	testCases := []struct {
		name             string
		sessionSaveError error
		wantStatusCode   int
		wantLocation     string
		wantRespBody     string
	}{
		{
			name:           "successful login",
			wantStatusCode: http.StatusFound,
			wantLocation:   "https://www.example.com/oauth/authorize?client_id=foo&code_challenge=RdoE4fOeAO8YelxeEEd70qNDoVgzl4844utzxsozlR4&code_challenge_method=S256&redirect_uri=https%3A%2F%2Fwww.example.com%2Fcallback&response_type=code&scope=tweet.read+tweet.write+users.read+offline.access&state=state",
		},
		{
			name:             "error saving session",
			wantStatusCode:   http.StatusInternalServerError,
			sessionSaveError: errors.New("boom"),
			wantRespBody:     "unexpected error",
		},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			var mockSessionStore mocks.SessionStore
			sess := sessions.NewSession(&mockSessionStore, "elon_session")
			mockSessionStore.On("Get", mock.Anything, "elon_session").Return(sess, nil)
			mockSessionStore.On("Save", mock.Anything, mock.Anything, sess).Return(tc.sessionSaveError)

			handler := httpserver.NewHandler(
				config.Config{
					Twitter: config.TwitterConfig{
						ClientID:     "foo",
						ClientSecret: "bar",
						CallbackURL:  "https://www.example.com/callback",
						AuthorizeURL: "https://www.example.com/oauth/authorize",
						TokenURL:     "https://www.example.com/oauth/token",
					},
				},
				templates,
				&mocks.Store{},
				func(*http.Client) httpserver.TwitterAPIClient { return &mocks.TwitterAPIClient{} },
				&mockSessionStore,
				&mockTokenGenerator{tokens: []string{"state", "pkceVerifier"}},
				zap.NewNop(),
			)

			req := httptest.NewRequest(http.MethodGet, "/login", nil)
			rec := httptest.NewRecorder()
			handler.ServeHTTP(rec, req)
			res := rec.Result()
			defer res.Body.Close()

			assert.Equal(t, tc.wantStatusCode, res.StatusCode)
			if tc.wantRespBody == "" {
				assert.Equal(t, tc.wantLocation, res.Header.Get("Location"))
			}

			if tc.wantRespBody != "" {
				body, err := ioutil.ReadAll(res.Body)
				require.NoError(t, err)
				assert.Contains(t, string(body), tc.wantRespBody)
			}
		})
	}
}

func TestCallback(t *testing.T) {
	testCases := []struct {
		name                string
		state               string
		sessionState        string
		sessionPkceVerifier string
		code                string
		sessionReadError    error
		oauth2StatusCode    int
		getTwitterUserError error
		createUserError     error
		wantStatusCode      int
		wantError           string
	}{
		{
			name:             "unable to read session",
			sessionReadError: errors.New("boom"),
			wantStatusCode:   http.StatusBadRequest,
			wantError:        "error reading session",
		},
		{
			name:           "missing state",
			state:          "mystate",
			sessionState:   "",
			wantStatusCode: http.StatusBadRequest,
			wantError:      "error validating request",
		},
		{
			name:           "unexpected state",
			state:          "mystate",
			sessionState:   "foostate",
			wantStatusCode: http.StatusBadRequest,
			wantError:      "error validating request",
		},
		{
			name:           "empty code",
			state:          "mystate",
			sessionState:   "mystate",
			code:           "",
			wantStatusCode: http.StatusBadRequest,
			wantError:      "invalid code",
		},
		{
			name:                "empty pkce verifier",
			state:               "mystate",
			sessionState:        "mystate",
			code:                "mycode",
			sessionPkceVerifier: "",
			wantStatusCode:      http.StatusBadRequest,
			wantError:           "error reading session",
		},
		{
			name:                "error exchanging code",
			state:               "mystate",
			sessionState:        "mystate",
			code:                "mycode",
			sessionPkceVerifier: "mypkceverifier",
			oauth2StatusCode:    http.StatusInternalServerError,
			wantStatusCode:      http.StatusForbidden,
			wantError:           "error exchanging code",
		},
		{
			name:                "error fetching user from twitter",
			state:               "mystate",
			sessionState:        "mystate",
			code:                "mycode",
			sessionPkceVerifier: "mypkceverifier",
			oauth2StatusCode:    http.StatusOK,
			getTwitterUserError: errors.New("nothing to see here"),
			wantStatusCode:      http.StatusInternalServerError,
			wantError:           "error validating user",
		},
		{
			name:                "error storing user",
			state:               "mystate",
			sessionState:        "mystate",
			code:                "mycode",
			sessionPkceVerifier: "mypkceverifier",
			oauth2StatusCode:    http.StatusOK,
			createUserError:     errors.New("oh no"),
			wantStatusCode:      http.StatusInternalServerError,
			wantError:           "error saving user",
		},
		{
			name:                "successful exchange",
			state:               "mystate",
			sessionState:        "mystate",
			code:                "mycode",
			sessionPkceVerifier: "mypkceverifier",
			oauth2StatusCode:    http.StatusOK,
			wantStatusCode:      http.StatusOK,
		},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			var mockSessionStore mocks.SessionStore
			sess := sessions.NewSession(&mockSessionStore, "elon_session")
			sess.Values["state"] = tc.sessionState
			sess.Values["pkce_verifier"] = tc.sessionPkceVerifier
			mockSessionStore.On("Get", mock.Anything, "elon_session").Return(sess, tc.sessionReadError)

			var mockTwitterClient mocks.TwitterAPIClient
			mockTwitterClient.On("GetMe").Return(&twitter.User{ID: "1", Name: "foo", Username: "Foo Bar"}, tc.getTwitterUserError)

			var mockStore mocks.Store
			mockStore.On("CreateUser", mock.Anything, mock.MatchedBy(func(params store.CreateUserParams) bool {
				return params.TwitterID == "1" && params.Name == "foo" && params.Username == "Foo Bar"
			})).Return(store.User{}, tc.createUserError)

			const callbackURL = "https://www.example.com/callback"
			oauthHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
				assert.Equal(t, http.MethodPost, r.Method)
				assert.Equal(t, "/oauth/token", r.URL.Path)

				require.NoError(t, r.ParseForm())
				assert.Equal(t, tc.code, r.PostFormValue("code"))
				assert.Equal(t, tc.sessionPkceVerifier, r.PostFormValue("code_verifier"))
				assert.Equal(t, "authorization_code", r.PostFormValue("grant_type"))
				assert.Equal(t, callbackURL, r.PostFormValue("redirect_uri"))

				w.WriteHeader(tc.oauth2StatusCode)
				if tc.oauth2StatusCode == http.StatusOK {
					w.Write([]byte(`access_token=foo&expires_in=3600&refresh_token=&token_type=bearer"}`))
				}
			})
			srv := httptest.NewServer(oauthHandler)

			handler := httpserver.NewHandler(
				config.Config{
					Twitter: config.TwitterConfig{
						ClientID:     "foo",
						ClientSecret: "bar",
						CallbackURL:  callbackURL,
						AuthorizeURL: srv.URL + "/oauth/authorize",
						TokenURL:     srv.URL + "/oauth/token",
					},
				},
				templates,
				&mockStore,
				func(*http.Client) httpserver.TwitterAPIClient { return &mockTwitterClient },
				&mockSessionStore,
				nil,
				zap.NewNop(),
			)

			req := httptest.NewRequest(http.MethodGet, "/callback?state="+tc.state+"&code="+tc.code, nil)
			rec := httptest.NewRecorder()
			handler.ServeHTTP(rec, req)
			res := rec.Result()
			defer res.Body.Close()

			assert.Equal(t, tc.wantStatusCode, res.StatusCode)

			if tc.wantError != "" {
				body, err := ioutil.ReadAll(res.Body)
				require.NoError(t, err)
				assert.Contains(t, string(body), tc.wantError)
			}
		})
	}
}