package session

import (
	"log/slog"
	"net/http"
	"net/http/httptest"
	"os"
	"testing"

	"github.com/gorilla/sessions"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"sneak.berlin/go/webhooker/internal/config"
)

// testSession creates a Session with a real cookie store for testing.
func testSession(t *testing.T) *Session {
	t.Helper()
	key := make([]byte, 32)
	for i := range key {
		key[i] = byte(i + 42)
	}
	store := sessions.NewCookieStore(key)
	store.Options = &sessions.Options{
		Path:     "/",
		MaxAge:   86400 * 7,
		HttpOnly: true,
		Secure:   false,
		SameSite: http.SameSiteLaxMode,
	}

	cfg := &config.Config{
		Environment: config.EnvironmentDev,
	}
	log := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelDebug}))

	return NewForTest(store, cfg, log)
}

// --- Get and Save Tests ---

func TestGet_NewSession(t *testing.T) {
	t.Parallel()
	s := testSession(t)

	req := httptest.NewRequest(http.MethodGet, "/", nil)
	sess, err := s.Get(req)
	require.NoError(t, err)
	require.NotNil(t, sess)
	assert.True(t, sess.IsNew, "session should be new when no cookie is present")
}

func TestGet_ExistingSession(t *testing.T) {
	t.Parallel()
	s := testSession(t)

	// Create and save a session
	req1 := httptest.NewRequest(http.MethodGet, "/", nil)
	w1 := httptest.NewRecorder()

	sess1, err := s.Get(req1)
	require.NoError(t, err)
	sess1.Values["test_key"] = "test_value"
	require.NoError(t, s.Save(req1, w1, sess1))

	// Extract cookies
	cookies := w1.Result().Cookies()
	require.NotEmpty(t, cookies)

	// Make a new request with the session cookie
	req2 := httptest.NewRequest(http.MethodGet, "/", nil)
	for _, c := range cookies {
		req2.AddCookie(c)
	}

	sess2, err := s.Get(req2)
	require.NoError(t, err)
	assert.False(t, sess2.IsNew, "session should not be new when cookie is present")
	assert.Equal(t, "test_value", sess2.Values["test_key"])
}

func TestSave_SetsCookie(t *testing.T) {
	t.Parallel()
	s := testSession(t)

	req := httptest.NewRequest(http.MethodGet, "/", nil)
	w := httptest.NewRecorder()

	sess, err := s.Get(req)
	require.NoError(t, err)
	sess.Values["key"] = "value"

	err = s.Save(req, w, sess)
	require.NoError(t, err)

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

	// Verify the cookie has the expected name
	var found bool
	for _, c := range cookies {
		if c.Name == SessionName {
			found = true
			assert.True(t, c.HttpOnly, "session cookie should be HTTP-only")
			break
		}
	}
	assert.True(t, found, "should find a cookie named %s", SessionName)
}

// --- SetUser and User Retrieval Tests ---

func TestSetUser_SetsAllFields(t *testing.T) {
	t.Parallel()
	s := testSession(t)

	req := httptest.NewRequest(http.MethodGet, "/", nil)
	sess, err := s.Get(req)
	require.NoError(t, err)

	s.SetUser(sess, "user-abc-123", "alice")

	assert.Equal(t, "user-abc-123", sess.Values[UserIDKey])
	assert.Equal(t, "alice", sess.Values[UsernameKey])
	assert.Equal(t, true, sess.Values[AuthenticatedKey])
}

func TestGetUserID(t *testing.T) {
	t.Parallel()
	s := testSession(t)

	req := httptest.NewRequest(http.MethodGet, "/", nil)
	sess, err := s.Get(req)
	require.NoError(t, err)

	// Before setting user
	userID, ok := s.GetUserID(sess)
	assert.False(t, ok, "should return false when no user ID is set")
	assert.Empty(t, userID)

	// After setting user
	s.SetUser(sess, "user-xyz", "bob")
	userID, ok = s.GetUserID(sess)
	assert.True(t, ok)
	assert.Equal(t, "user-xyz", userID)
}

func TestGetUsername(t *testing.T) {
	t.Parallel()
	s := testSession(t)

	req := httptest.NewRequest(http.MethodGet, "/", nil)
	sess, err := s.Get(req)
	require.NoError(t, err)

	// Before setting user
	username, ok := s.GetUsername(sess)
	assert.False(t, ok, "should return false when no username is set")
	assert.Empty(t, username)

	// After setting user
	s.SetUser(sess, "user-xyz", "bob")
	username, ok = s.GetUsername(sess)
	assert.True(t, ok)
	assert.Equal(t, "bob", username)
}

// --- IsAuthenticated Tests ---

func TestIsAuthenticated_NoSession(t *testing.T) {
	t.Parallel()
	s := testSession(t)

	req := httptest.NewRequest(http.MethodGet, "/", nil)
	sess, err := s.Get(req)
	require.NoError(t, err)

	assert.False(t, s.IsAuthenticated(sess), "new session should not be authenticated")
}

func TestIsAuthenticated_AfterSetUser(t *testing.T) {
	t.Parallel()
	s := testSession(t)

	req := httptest.NewRequest(http.MethodGet, "/", nil)
	sess, err := s.Get(req)
	require.NoError(t, err)

	s.SetUser(sess, "user-123", "alice")
	assert.True(t, s.IsAuthenticated(sess))
}

func TestIsAuthenticated_AfterClearUser(t *testing.T) {
	t.Parallel()
	s := testSession(t)

	req := httptest.NewRequest(http.MethodGet, "/", nil)
	sess, err := s.Get(req)
	require.NoError(t, err)

	s.SetUser(sess, "user-123", "alice")
	require.True(t, s.IsAuthenticated(sess))

	s.ClearUser(sess)
	assert.False(t, s.IsAuthenticated(sess), "should not be authenticated after ClearUser")
}

func TestIsAuthenticated_WrongType(t *testing.T) {
	t.Parallel()
	s := testSession(t)

	req := httptest.NewRequest(http.MethodGet, "/", nil)
	sess, err := s.Get(req)
	require.NoError(t, err)

	// Set authenticated to a non-bool value
	sess.Values[AuthenticatedKey] = "yes"
	assert.False(t, s.IsAuthenticated(sess), "should return false for non-bool authenticated value")
}

// --- ClearUser Tests ---

func TestClearUser_RemovesAllKeys(t *testing.T) {
	t.Parallel()
	s := testSession(t)

	req := httptest.NewRequest(http.MethodGet, "/", nil)
	sess, err := s.Get(req)
	require.NoError(t, err)

	s.SetUser(sess, "user-123", "alice")
	s.ClearUser(sess)

	_, hasUserID := sess.Values[UserIDKey]
	assert.False(t, hasUserID, "UserIDKey should be removed")

	_, hasUsername := sess.Values[UsernameKey]
	assert.False(t, hasUsername, "UsernameKey should be removed")

	_, hasAuth := sess.Values[AuthenticatedKey]
	assert.False(t, hasAuth, "AuthenticatedKey should be removed")
}

// --- Destroy Tests ---

func TestDestroy_InvalidatesSession(t *testing.T) {
	t.Parallel()
	s := testSession(t)

	req := httptest.NewRequest(http.MethodGet, "/", nil)
	sess, err := s.Get(req)
	require.NoError(t, err)

	s.SetUser(sess, "user-123", "alice")

	s.Destroy(sess)

	// After Destroy: MaxAge should be -1 (delete cookie) and user data cleared
	assert.Equal(t, -1, sess.Options.MaxAge, "Destroy should set MaxAge to -1")
	assert.False(t, s.IsAuthenticated(sess), "should not be authenticated after Destroy")

	_, hasUserID := sess.Values[UserIDKey]
	assert.False(t, hasUserID, "Destroy should clear user ID")
}

// --- Session Persistence Round-Trip ---

func TestSessionPersistence_RoundTrip(t *testing.T) {
	t.Parallel()
	s := testSession(t)

	// Step 1: Create session, set user, save
	req1 := httptest.NewRequest(http.MethodGet, "/", nil)
	w1 := httptest.NewRecorder()

	sess1, err := s.Get(req1)
	require.NoError(t, err)
	s.SetUser(sess1, "user-round-trip", "charlie")
	require.NoError(t, s.Save(req1, w1, sess1))

	cookies := w1.Result().Cookies()
	require.NotEmpty(t, cookies)

	// Step 2: New request with cookies — session data should persist
	req2 := httptest.NewRequest(http.MethodGet, "/profile", nil)
	for _, c := range cookies {
		req2.AddCookie(c)
	}

	sess2, err := s.Get(req2)
	require.NoError(t, err)

	assert.True(t, s.IsAuthenticated(sess2), "session should be authenticated after round-trip")

	userID, ok := s.GetUserID(sess2)
	assert.True(t, ok)
	assert.Equal(t, "user-round-trip", userID)

	username, ok := s.GetUsername(sess2)
	assert.True(t, ok)
	assert.Equal(t, "charlie", username)
}

// --- Constants Tests ---

func TestSessionConstants(t *testing.T) {
	t.Parallel()
	assert.Equal(t, "webhooker_session", SessionName)
	assert.Equal(t, "user_id", UserIDKey)
	assert.Equal(t, "username", UsernameKey)
	assert.Equal(t, "authenticated", AuthenticatedKey)
}

// --- Edge Cases ---

func TestSetUser_OverwritesPreviousUser(t *testing.T) {
	t.Parallel()
	s := testSession(t)

	req := httptest.NewRequest(http.MethodGet, "/", nil)
	sess, err := s.Get(req)
	require.NoError(t, err)

	s.SetUser(sess, "user-1", "alice")
	assert.True(t, s.IsAuthenticated(sess))

	// Overwrite with a different user
	s.SetUser(sess, "user-2", "bob")

	userID, ok := s.GetUserID(sess)
	assert.True(t, ok)
	assert.Equal(t, "user-2", userID)

	username, ok := s.GetUsername(sess)
	assert.True(t, ok)
	assert.Equal(t, "bob", username)
}

func TestDestroy_ThenSave_DeletesCookie(t *testing.T) {
	t.Parallel()
	s := testSession(t)

	// Create a session
	req1 := httptest.NewRequest(http.MethodGet, "/", nil)
	w1 := httptest.NewRecorder()

	sess, err := s.Get(req1)
	require.NoError(t, err)
	s.SetUser(sess, "user-123", "alice")
	require.NoError(t, s.Save(req1, w1, sess))

	cookies := w1.Result().Cookies()
	require.NotEmpty(t, cookies)

	// Destroy and save
	req2 := httptest.NewRequest(http.MethodGet, "/logout", nil)
	for _, c := range cookies {
		req2.AddCookie(c)
	}
	w2 := httptest.NewRecorder()

	sess2, err := s.Get(req2)
	require.NoError(t, err)
	s.Destroy(sess2)
	require.NoError(t, s.Save(req2, w2, sess2))

	// The cookie should have MaxAge = -1 (browser should delete it)
	responseCookies := w2.Result().Cookies()
	var sessionCookie *http.Cookie
	for _, c := range responseCookies {
		if c.Name == SessionName {
			sessionCookie = c
			break
		}
	}
	require.NotNil(t, sessionCookie, "should have a session cookie in response")
	assert.True(t, sessionCookie.MaxAge < 0, "destroyed session cookie should have negative MaxAge")
}