package server

import (
	"net/http"
	"net/http/httptest"
	"net/url"
	"regexp"
	"strings"
	"testing"

	"go.uber.org/fx"
	"go.uber.org/fx/fxtest"

	"sneak.berlin/go/pixa/internal/config"
	"sneak.berlin/go/pixa/internal/database"
	"sneak.berlin/go/pixa/internal/globals"
	"sneak.berlin/go/pixa/internal/handlers"
	"sneak.berlin/go/pixa/internal/healthcheck"
	"sneak.berlin/go/pixa/internal/logger"
	"sneak.berlin/go/pixa/internal/middleware"
	"sneak.berlin/go/pixa/internal/session"
)

// logoutFormPattern extracts the CSRF token rendered into the generator
// page's logout form.
var logoutFormPattern = regexp.MustCompile(
	`(?s)action="/logout".*?name="gorilla\.csrf\.Token" value="([^"]+)"`)

// startPixa starts the components pixad's fx app builds, from cfg, and
// returns the server with its routes, as newTestServer does.
func startPixa(t *testing.T, cfg *config.Config) *Server {
	t.Helper()

	var (
		h  *handlers.Handlers
		mw *middleware.Middleware
	)

	app := fxtest.New(t,
		fx.Supply(cfg),
		fx.Provide(
			globals.New,
			logger.New,
			database.New,
			healthcheck.New,
			handlers.New,
			middleware.New,
		),
		fx.Populate(&h, &mw),
	)
	app.RequireStart()
	t.Cleanup(app.RequireStop)

	s := &Server{config: cfg, mw: mw, h: h}
	s.SetupRoutes()

	return s
}

// logIn logs in to s with the signing key, as postLogin does, and returns
// the session cookie it sets.
func logIn(t *testing.T, s *Server) *http.Cookie {
	t.Helper()

	rec := postLogin(t, s, firstClient, "", testSigningKey)

	for _, c := range rec.Result().Cookies() {
		if c.Name == session.CookieName {
			return c
		}
	}

	t.Fatal("logging in set no session cookie")

	return nil
}

// opensGeneratorPage reports whether GET / with cookie shows s's generator
// page, which only a valid login session opens.
func opensGeneratorPage(t *testing.T, s *Server, cookie *http.Cookie) bool {
	t.Helper()

	req := httptest.NewRequestWithContext(t.Context(), http.MethodGet, "/", nil)
	req.AddCookie(cookie)

	rec := httptest.NewRecorder()
	s.ServeHTTP(rec, req)

	return rec.Code == http.StatusOK &&
		strings.Contains(rec.Body.String(), `action="/generate"`)
}

// postLogout loads the generator page with GET / and sessionCookie and
// submits its logout form with POST /logout, as a browser does.
func postLogout(
	t *testing.T, s *Server, sessionCookie *http.Cookie,
) *httptest.ResponseRecorder {
	t.Helper()

	req := httptest.NewRequestWithContext(t.Context(), http.MethodGet, "/", nil)
	req.AddCookie(sessionCookie)

	page := httptest.NewRecorder()
	s.ServeHTTP(page, req)

	match := logoutFormPattern.FindStringSubmatch(page.Body.String())
	if match == nil {
		t.Fatal("the generator page has no logout form with a CSRF token")
	}

	form := url.Values{"gorilla.csrf.Token": {match[1]}}
	req = httptest.NewRequestWithContext(t.Context(), http.MethodPost,
		"/logout", strings.NewReader(form.Encode()))
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	req.AddCookie(sessionCookie)

	for _, c := range page.Result().Cookies() {
		req.AddCookie(c)
	}

	rec := httptest.NewRecorder()
	s.ServeHTTP(rec, req)

	return rec
}

// TestLogoutWithoutCSRFTokenEndsNoSession verifies that a request to /logout
// carrying the session cookie but not the logout form's CSRF token ends no
// session: GET /logout, as an image on another page of the same site makes a
// browser send, answers 405, and POST /logout without the token answers 403.
func TestLogoutWithoutCSRFTokenEndsNoSession(t *testing.T) {
	t.Parallel()

	tests := []struct {
		method string
		want   int
	}{
		{http.MethodGet, http.StatusMethodNotAllowed},
		{http.MethodPost, http.StatusForbidden},
	}

	for _, tc := range tests {
		t.Run(tc.method, func(t *testing.T) {
			t.Parallel()

			s := newTestServer(t)
			cookie := logIn(t, s)

			req := httptest.NewRequestWithContext(
				t.Context(), tc.method, "/logout", nil)
			req.AddCookie(cookie)

			rec := httptest.NewRecorder()
			s.ServeHTTP(rec, req)
			t.Logf("%s /logout without the CSRF token: status %d",
				tc.method, rec.Code)

			if rec.Code != tc.want {
				t.Errorf("%s /logout without the CSRF token status = %d, "+
					"want %d", tc.method, rec.Code, tc.want)
			}

			if !opensGeneratorPage(t, s, cookie) {
				t.Errorf("%s /logout without the CSRF token ended the "+
					"login session", tc.method)
			}
		})
	}
}

// TestLoginAfterLogoutOpensGeneratorPage verifies that after a logout from
// the generator page a copy of the session cookie taken before it is
// refused, and that a login after it opens the generator page.
func TestLoginAfterLogoutOpensGeneratorPage(t *testing.T) {
	t.Parallel()

	s := newTestServer(t)

	copied := logIn(t, s)
	if !opensGeneratorPage(t, s, copied) {
		t.Fatal("logging in did not open the generator page")
	}

	logout := postLogout(t, s, copied)
	if logout.Code != http.StatusSeeOther {
		t.Fatalf("POST /logout status = %d, want %d",
			logout.Code, http.StatusSeeOther)
	}

	if opensGeneratorPage(t, s, copied) {
		t.Error("a cookie copied before the logout still opens the " +
			"generator page")
	}

	opens := opensGeneratorPage(t, s, logIn(t, s))
	t.Logf("a login after the logout opens the generator page: %v", opens)

	if !opens {
		t.Error("a login after the logout does not open the generator page")
	}
}

// TestLogoutOutlastsRestart verifies that a copy of the session cookie taken
// before a logout is still refused by a pixa started again on the same state
// directory, as pixad is after a restart.
func TestLogoutOutlastsRestart(t *testing.T) {
	t.Parallel()

	s := newTestServer(t)

	copied := logIn(t, s)
	if !opensGeneratorPage(t, s, copied) {
		t.Fatal("logging in did not open the generator page")
	}

	logout := postLogout(t, s, copied)
	if logout.Code != http.StatusSeeOther {
		t.Fatalf("POST /logout status = %d, want %d",
			logout.Code, http.StatusSeeOther)
	}

	restarted := startPixa(t, s.config)

	opens := opensGeneratorPage(t, restarted, copied)
	t.Logf("after the restart, the copied cookie opens the generator page: %v",
		opens)

	if opens {
		t.Error("after a restart, a cookie copied before the logout " +
			"still opens the generator page")
	}
}