[feature] New user sign-up via web page (#2796)

* [feature] User sign-up form and admin notifs

* add chosen + filtered languages to migration

* remove stray comment

* chosen languages schmosen schmanguages

* proper error on local account missing

internal/web/confirmemail.go

@@ -56,18 +56,84 @@ func (m *Module) confirmEmailGETHandler(c *gin.Context) {
 		return
 	}
 
+	// Get user but don't confirm yet.
+	user, errWithCode := m.processor.User().EmailGetUserForConfirmToken(c.Request.Context(), token)
+	if errWithCode != nil {
+		apiutil.WebErrorHandler(c, errWithCode, instanceGet)
+		return
+	}
+
+	// They may have already confirmed before
+	// and are visiting the link again for
+	// whatever reason. This is fine, just make
+	// sure we have an email address to show them.
+	email := user.UnconfirmedEmail
+	if email == "" {
+		// Already confirmed, take
+		// that address instead.
+		email = user.Email
+	}
+
+	// Serve page where user can click button
+	// to POST confirmation to same endpoint.
+	page := apiutil.WebPage{
+		Template: "confirm_email.tmpl",
+		Instance: instance,
+		Extra: map[string]any{
+			"email":    email,
+			"username": user.Account.Username,
+			"token":    token,
+		},
+	}
+
+	apiutil.TemplateWebPage(c, page)
+}
+
+func (m *Module) confirmEmailPOSTHandler(c *gin.Context) {
+	instance, errWithCode := m.processor.InstanceGetV1(c.Request.Context())
+	if errWithCode != nil {
+		apiutil.WebErrorHandler(c, errWithCode, m.processor.InstanceGetV1)
+		return
+	}
+
+	// Return instance we already got from the db,
+	// don't try to fetch it again when erroring.
+	instanceGet := func(ctx context.Context) (*apimodel.InstanceV1, gtserror.WithCode) {
+		return instance, nil
+	}
+
+	// We only serve text/html at this endpoint.
+	if _, err := apiutil.NegotiateAccept(c, apiutil.TextHTML); err != nil {
+		apiutil.WebErrorHandler(c, gtserror.NewErrorNotAcceptable(err, err.Error()), instanceGet)
+		return
+	}
+
+	// If there's no token in the query,
+	// just serve the 404 web handler.
+	token := c.Query("token")
+	if token == "" {
+		errWithCode := gtserror.NewErrorNotFound(errors.New(http.StatusText(http.StatusNotFound)))
+		apiutil.WebErrorHandler(c, errWithCode, instanceGet)
+		return
+	}
+
+	// Confirm email address for real this time.
 	user, errWithCode := m.processor.User().EmailConfirm(c.Request.Context(), token)
 	if errWithCode != nil {
 		apiutil.WebErrorHandler(c, errWithCode, instanceGet)
 		return
 	}
 
+	// Serve page informing user that their
+	// email address is now confirmed.
 	page := apiutil.WebPage{
-		Template: "confirmed.tmpl",
+		Template: "confirmed_email.tmpl",
 		Instance: instance,
 		Extra: map[string]any{
 			"email":    user.Email,
 			"username": user.Account.Username,
+			"token":    token,
+			"approved": *user.Approved,
 		},
 	}