feat(op): Server interface (#447)

* first draft of a new server interface

* allow any response type

* complete interface docs

* refelct the format from the proposal

* intermediate commit with some methods implemented

* implement remaining token grant type methods

* implement remaining server methods

* error handling

* rewrite auth request validation

* define handlers, routes

* input validation and concrete handlers

* check if client credential client is authenticated

* copy and modify the routes test for the legacy server

* run integration tests against both Server and Provider

* remove unuse ValidateAuthRequestV2 function

* unit tests for error handling

* cleanup tokenHandler

* move server routest test

* unit test authorize

* handle client credentials in VerifyClient

* change code exchange route test

* finish http unit tests

* review server interface docs and spelling

* add withClient unit test

* server options

* cleanup unused GrantType method

* resolve typo comments

* make endpoints pointers to enable/disable them

* jwt profile base work

* jwt: correct the test expect

---------

Co-authored-by: Livio Spring <livio.a@gmail.com>

pkg/op/op_test.go

@@ -395,3 +395,54 @@ func TestRoutes(t *testing.T) {
 		})
 	}
 }
+
+func TestWithCustomEndpoints(t *testing.T) {
+	type args struct {
+		auth       *op.Endpoint
+		token      *op.Endpoint
+		userInfo   *op.Endpoint
+		revocation *op.Endpoint
+		endSession *op.Endpoint
+		keys       *op.Endpoint
+	}
+	tests := []struct {
+		name    string
+		args    args
+		wantErr error
+	}{
+		{
+			name:    "all nil",
+			args:    args{},
+			wantErr: op.ErrNilEndpoint,
+		},
+		{
+			name: "all set",
+			args: args{
+				auth:       op.NewEndpoint("/authorize"),
+				token:      op.NewEndpoint("/oauth/token"),
+				userInfo:   op.NewEndpoint("/userinfo"),
+				revocation: op.NewEndpoint("/revoke"),
+				endSession: op.NewEndpoint("/end_session"),
+				keys:       op.NewEndpoint("/keys"),
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			provider, err := op.NewOpenIDProvider(testIssuer, testConfig,
+				storage.NewStorage(storage.NewUserStore(testIssuer)),
+				op.WithCustomEndpoints(tt.args.auth, tt.args.token, tt.args.userInfo, tt.args.revocation, tt.args.endSession, tt.args.keys),
+			)
+			require.ErrorIs(t, err, tt.wantErr)
+			if tt.wantErr != nil {
+				return
+			}
+			assert.Equal(t, tt.args.auth, provider.AuthorizationEndpoint())
+			assert.Equal(t, tt.args.token, provider.TokenEndpoint())
+			assert.Equal(t, tt.args.userInfo, provider.UserinfoEndpoint())
+			assert.Equal(t, tt.args.revocation, provider.RevocationEndpoint())
+			assert.Equal(t, tt.args.endSession, provider.EndSessionEndpoint())
+			assert.Equal(t, tt.args.keys, provider.KeysEndpoint())
+		})
+	}
+}