[chore] The Big Middleware and API Refactor (tm) (#1250)

* interim commit: start refactoring middlewares into package under router

* another interim commit, this is becoming a big job

* another fucking massive interim commit

* refactor bookmarks to new style

* ambassador, wiz zeze commits you are spoiling uz

* she compiles, we're getting there

* we're just normal men; we're just innocent men

* apiutil

* whoopsie

* i'm glad noone reads commit msgs haha :blob_sweat:

* use that weirdo go-bytesize library for maxMultipartMemory

* fix media module paths

1 files changed, 117 insertions, 0 deletions

diff --git a/internal/api/auth/auth.go b/internal/api/auth/auth.go
new file mode 100644
index 000000000..7ce992466
--- /dev/null
+++ b/internal/api/auth/auth.go
@@ -0,0 +1,117 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package auth
+
+import (
+	"net/http"
+
+	"github.com/gin-contrib/sessions"
+	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/oidc"
+	"github.com/superseriousbusiness/gotosocial/internal/processing"
+)
+
+const (
+	/*
+		paths prefixed with 'auth'
+	*/
+
+	// AuthSignInPath is the API path for users to sign in through
+	AuthSignInPath = "/sign_in"
+	// AuthCheckYourEmailPath users land here after registering a new account, instructs them to confirm their email
+	AuthCheckYourEmailPath = "/check_your_email"
+	// AuthWaitForApprovalPath users land here after confirming their email
+	// but before an admin approves their account (if such is required)
+	AuthWaitForApprovalPath = "/wait_for_approval"
+	// AuthAccountDisabledPath users land here when their account is suspended by an admin
+	AuthAccountDisabledPath = "/account_disabled"
+	// AuthCallbackPath is the API path for receiving callback tokens from external OIDC providers
+	AuthCallbackPath = "/callback"
+
+	/*
+		paths prefixed with 'oauth'
+	*/
+
+	// OauthTokenPath is the API path to use for granting token requests to users with valid credentials
+	OauthTokenPath = "/token" // #nosec G101 else we get a hardcoded credentials warning
+	// OauthAuthorizePath is the API path for authorization requests (eg., authorize this app to act on my behalf as a user)
+	OauthAuthorizePath = "/authorize"
+	// OauthFinalizePath is the API path for completing user registration with additional user details
+	OauthFinalizePath = "/finalize"
+	// OauthOobTokenPath is the path for serving an html representation of an oob token page.
+	OauthOobTokenPath = "/oob" // #nosec G101 else we get a hardcoded credentials warning
+
+	/*
+		params / session keys
+	*/
+
+	callbackStateParam   = "state"
+	callbackCodeParam    = "code"
+	sessionUserID        = "userid"
+	sessionClientID      = "client_id"
+	sessionRedirectURI   = "redirect_uri"
+	sessionForceLogin    = "force_login"
+	sessionResponseType  = "response_type"
+	sessionScope         = "scope"
+	sessionInternalState = "internal_state"
+	sessionClientState   = "client_state"
+	sessionClaims        = "claims"
+	sessionAppID         = "app_id"
+)
+
+type Module struct {
+	db        db.DB
+	processor processing.Processor
+	idp       oidc.IDP
+}
+
+// New returns an Auth module which provides both 'oauth' and 'auth' endpoints.
+//
+// It is safe to pass a nil idp if oidc is disabled.
+func New(db db.DB, processor processing.Processor, idp oidc.IDP) *Module {
+	return &Module{
+		db:        db,
+		processor: processor,
+		idp:       idp,
+	}
+}
+
+// RouteAuth routes all paths that should have an 'auth' prefix
+func (m *Module) RouteAuth(attachHandler func(method string, path string, f ...gin.HandlerFunc) gin.IRoutes) {
+	attachHandler(http.MethodGet, AuthSignInPath, m.SignInGETHandler)
+	attachHandler(http.MethodPost, AuthSignInPath, m.SignInPOSTHandler)
+	attachHandler(http.MethodGet, AuthCallbackPath, m.CallbackGETHandler)
+}
+
+// RouteOauth routes all paths that should have an 'oauth' prefix
+func (m *Module) RouteOauth(attachHandler func(method string, path string, f ...gin.HandlerFunc) gin.IRoutes) {
+	attachHandler(http.MethodPost, OauthTokenPath, m.TokenPOSTHandler)
+	attachHandler(http.MethodGet, OauthAuthorizePath, m.AuthorizeGETHandler)
+	attachHandler(http.MethodPost, OauthAuthorizePath, m.AuthorizePOSTHandler)
+	attachHandler(http.MethodPost, OauthFinalizePath, m.FinalizePOSTHandler)
+	attachHandler(http.MethodGet, OauthOobTokenPath, m.OobHandler)
+}
+
+func (m *Module) clearSession(s sessions.Session) {
+	s.Clear()
+	if err := s.Save(); err != nil {
+		panic(err)
+	}
+}