package server_test

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

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"go.uber.org/fx"
	"go.uber.org/fx/fxtest"
	"sneak.berlin/go/webhooker/internal/config"
	"sneak.berlin/go/webhooker/internal/database"
	"sneak.berlin/go/webhooker/internal/delivery"
	"sneak.berlin/go/webhooker/internal/globals"
	"sneak.berlin/go/webhooker/internal/handlers"
	"sneak.berlin/go/webhooker/internal/healthcheck"
	"sneak.berlin/go/webhooker/internal/logger"
	"sneak.berlin/go/webhooker/internal/middleware"
	"sneak.berlin/go/webhooker/internal/server"
	"sneak.berlin/go/webhooker/internal/session"
)

// csrfCookieName is the cookie gorilla/csrf issues when it runs. Its
// presence or absence on a response is how these tests tell whether
// the CSRF middleware executed.
const csrfCookieName = "_gorilla_csrf"

type noopNotifier struct{}

func (n *noopNotifier) Notify([]delivery.Task) {}

// testEnv is the real router from routes.go plus the collaborators
// tests need to seed users and forge sessions.
type testEnv struct {
	router http.Handler
	sess   *session.Session
	db     *database.Database
}

// newTestEnv wires the dependency graph with fx and builds the
// production route tree, so middleware registration order is
// exercised exactly as it ships.
func newTestEnv(t *testing.T) *testEnv {
	t.Helper()

	var (
		log  *logger.Logger
		cfg  *config.Config
		mw   *middleware.Middleware
		hnd  *handlers.Handlers
		sess *session.Session
		db   *database.Database
	)

	app := fxtest.New(
		t,
		fx.Provide(
			globals.New,
			logger.New,
			func() *config.Config {
				return &config.Config{
					DataDir:     t.TempDir(),
					Environment: config.EnvironmentDev,
				}
			},
			database.New,
			database.NewWebhookDBManager,
			healthcheck.New,
			session.New,
			func() delivery.Notifier { return &noopNotifier{} },
			middleware.New,
			handlers.New,
		),
		fx.Populate(&log, &cfg, &mw, &hnd, &sess, &db),
	)
	app.RequireStart()
	t.Cleanup(app.RequireStop)

	return &testEnv{
		router: server.NewRouterForTest(log.Get(), cfg, mw, hnd),
		sess:   sess,
		db:     db,
	}
}

// oversizeValue returns a form value one byte past the route-group
// body cap, so an encoded form containing it is guaranteed oversize.
func oversizeValue() string {
	return strings.Repeat("a", int(server.MaxFormBodySizeForTest)+1)
}

// csrfCookieSet reports whether the response issued a gorilla/csrf
// cookie, which only happens if the CSRF middleware ran.
func csrfCookieSet(w *httptest.ResponseRecorder) bool {
	for _, c := range w.Result().Cookies() {
		if c.Name == csrfCookieName {
			return true
		}
	}

	return false
}

// get issues a GET through the router with the supplied cookies.
func (e *testEnv) get(
	path string,
	cookies []*http.Cookie,
) *httptest.ResponseRecorder {
	req := httptest.NewRequestWithContext(
		context.Background(), http.MethodGet, path, nil,
	)

	for _, c := range cookies {
		req.AddCookie(c)
	}

	w := httptest.NewRecorder()
	e.router.ServeHTTP(w, req)

	return w
}

// post issues a urlencoded form POST through the router. The body is
// a strings.Reader, so the request carries an accurate
// Content-Length — the signal MaxBodySize checks up front.
func (e *testEnv) post(
	path string,
	form url.Values,
	cookies []*http.Cookie,
) *httptest.ResponseRecorder {
	req := httptest.NewRequestWithContext(
		context.Background(), http.MethodPost, path,
		strings.NewReader(form.Encode()),
	)
	req.Header.Set(
		"Content-Type", "application/x-www-form-urlencoded",
	)

	for _, c := range cookies {
		req.AddCookie(c)
	}

	w := httptest.NewRecorder()
	e.router.ServeHTTP(w, req)

	return w
}

// csrfFrom renders the page at path and returns the CSRF token from
// its form together with every cookie needed for the follow-up POST.
func (e *testEnv) csrfFrom(
	t *testing.T,
	path string,
	cookies []*http.Cookie,
) (string, []*http.Cookie) {
	t.Helper()

	w := e.get(path, cookies)
	require.Equal(t, http.StatusOK, w.Code)

	pattern := regexp.MustCompile(
		`name="csrf_token" value="([^"]+)"`,
	)

	match := pattern.FindStringSubmatch(w.Body.String())
	require.Len(t, match, 2, "form must embed a CSRF token")

	// html/template escapes "+" and "=" in attribute values, and
	// gorilla/csrf tokens are standard base64, so the value read
	// out of the markup has to be unescaped before it is submitted.
	token := html.UnescapeString(match[1])

	combined := make([]*http.Cookie, 0, len(cookies))
	combined = append(combined, cookies...)
	combined = append(combined, w.Result().Cookies()...)

	return token, combined
}

// authCookies forges an authenticated session for the given user.
func (e *testEnv) authCookies(
	t *testing.T,
	userID, username string,
) []*http.Cookie {
	t.Helper()

	req := httptest.NewRequestWithContext(
		context.Background(), http.MethodGet, "/setup", nil,
	)
	w := httptest.NewRecorder()

	s, err := e.sess.Get(req)
	require.NoError(t, err)

	e.sess.SetUser(s, userID, username)
	require.NoError(t, e.sess.Save(req, w, s))

	cookies := w.Result().Cookies()
	require.NotEmpty(t, cookies, "session cookie should be set")

	return cookies
}

// seedUser creates a user with the given password and returns the
// stored hash so tests can assert whether it later changed.
func (e *testEnv) seedUser(
	t *testing.T,
	username, password string,
) (string, string) {
	t.Helper()

	hash, err := database.HashPassword(password)
	require.NoError(t, err)

	user := &database.User{Username: username, Password: hash}
	require.NoError(t, e.db.DB().Create(user).Error)

	return user.ID, hash
}

// storedHash reads the current password hash for a username.
func (e *testEnv) storedHash(t *testing.T, username string) string {
	t.Helper()

	var user database.User

	require.NoError(t,
		e.db.DB().Where("username = ?", username).
			First(&user).Error,
	)

	return user.Password
}

// --- /pages group ---

// TestPagesLogin_OversizeBody_RejectedBeforeCSRF proves the cap runs
// ahead of gorilla/csrf: the response is a clean 413 and no CSRF
// cookie was issued, so neither the CSRF middleware nor the login
// handler ran.
func TestPagesLogin_OversizeBody_RejectedBeforeCSRF(t *testing.T) {
	t.Parallel()

	env := newTestEnv(t)

	form := url.Values{}
	form.Set("username", oversizeValue())
	form.Set("password", "irrelevant")

	w := env.post("/pages/login", form, nil)

	assert.Equal(
		t, http.StatusRequestEntityTooLarge, w.Code,
	)
	assert.False(
		t, csrfCookieSet(w),
		"CSRF middleware must not run for an oversized body",
	)
}

// TestPagesLogin_UnderLimit_NoToken_CSRFRejects is the control for
// the test above: an identically shaped but under-limit POST does
// reach gorilla/csrf, which rejects it and issues its cookie. Without
// this, the missing-cookie assertion above would prove nothing.
func TestPagesLogin_UnderLimit_NoToken_CSRFRejects(t *testing.T) {
	t.Parallel()

	env := newTestEnv(t)

	form := url.Values{}
	form.Set("username", "someone")
	form.Set("password", "irrelevant")

	w := env.post("/pages/login", form, nil)

	assert.Equal(t, http.StatusForbidden, w.Code)
	assert.True(
		t, csrfCookieSet(w),
		"CSRF middleware should run for an under-limit body",
	)
}

// TestPagesLogin_UnderLimit_ValidToken_ReachesHandler proves the
// reorder did not break CSRF token handling: a token harvested from
// the rendered login form is still accepted and the request lands in
// the handler.
func TestPagesLogin_UnderLimit_ValidToken_ReachesHandler(
	t *testing.T,
) {
	t.Parallel()

	env := newTestEnv(t)

	token, cookies := env.csrfFrom(t, "/pages/login", nil)

	form := url.Values{}
	form.Set("csrf_token", token)
	form.Set("username", "nosuchuser")
	form.Set("password", "wrongpassword")

	w := env.post("/pages/login", form, cookies)

	assert.Equal(t, http.StatusUnauthorized, w.Code)
	assert.Contains(
		t, w.Body.String(), "Invalid username or password",
		"request should reach the login handler",
	)
}

// --- /user/{username} group ---

// TestPasswordChange_OversizeBody_RejectedAndPasswordUnchanged
// covers the route that previously had no middleware body cap at
// all. The request carries a valid session and a valid CSRF token,
// so the only thing that can stop it is the size cap; the unchanged
// password hash is the observable proof the handler never ran.
func TestPasswordChange_OversizeBody_RejectedAndPasswordUnchanged(
	t *testing.T,
) {
	t.Parallel()

	env := newTestEnv(t)

	userID, originalHash := env.seedUser(t, "pwuser", "oldpassword")
	cookies := env.authCookies(t, userID, "pwuser")
	token, cookies := env.csrfFrom(t, "/user/pwuser/", cookies)

	form := url.Values{}
	form.Set("csrf_token", token)
	form.Set("current_password", "oldpassword")
	form.Set("new_password", oversizeValue())
	form.Set("confirm_password", oversizeValue())

	w := env.post("/user/pwuser/password", form, cookies)

	assert.Equal(
		t, http.StatusRequestEntityTooLarge, w.Code,
	)
	assert.Equal(
		t, originalHash, env.storedHash(t, "pwuser"),
		"handler must not run, so the password must be unchanged",
	)
}

// TestPasswordChange_UnderLimit_Succeeds proves that adding the cap
// to the /user/{username} group did not break the route it guards.
func TestPasswordChange_UnderLimit_Succeeds(t *testing.T) {
	t.Parallel()

	env := newTestEnv(t)

	userID, originalHash := env.seedUser(t, "okuser", "oldpassword")
	cookies := env.authCookies(t, userID, "okuser")
	token, cookies := env.csrfFrom(t, "/user/okuser/", cookies)

	form := url.Values{}
	form.Set("csrf_token", token)
	form.Set("current_password", "oldpassword")
	form.Set("new_password", "brandnewpassword")
	form.Set("confirm_password", "brandnewpassword")

	w := env.post("/user/okuser/password", form, cookies)

	assert.Equal(t, http.StatusOK, w.Code)
	assert.NotEqual(
		t, originalHash, env.storedHash(t, "okuser"),
		"an under-limit password change should still apply",
	)
}