Add connector with OAuth2 support

Signed-off-by: Bryan Frimin <bryan@getprobo.com>

pkg/connector/connector.go

@@ -0,0 +1,68 @@
+// Copyright (c) 2025 Probo Inc <hello@getprobo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+package connector
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+)
+
+type (
+	ProtocolType string
+
+	Connector interface {
+		Initiate(ctx context.Context, connectorID string, organizationID string, r *http.Request) (string, error)
+		Complete(ctx context.Context, connectorID string, organizationID string, r *http.Request) (Connection, error)
+	}
+
+	Connection interface {
+		Type() ProtocolType
+		Client(ctx context.Context) (*http.Client, error)
+
+		json.Unmarshaler
+		json.Marshaler
+	}
+)
+
+const (
+	ProtocolOAuth2 ProtocolType = "oauth2"
+)
+
+func UnmarshalConnection(data []byte) (Connection, error) {
+	var typeContainer struct {
+		Type string `json:"type"`
+	}
+
+	if err := json.Unmarshal(data, &typeContainer); err != nil {
+		return nil, fmt.Errorf("failed to unmarshal connection type: %w", err)
+	}
+
+	var conn Connection
+
+	switch ProtocolType(typeContainer.Type) {
+	case ProtocolOAuth2:
+		conn = &OAuth2Connection{}
+	default:
+		return nil, fmt.Errorf("unknown connection type: %s", typeContainer.Type)
+	}
+
+	if err := conn.UnmarshalJSON(data); err != nil {
+		return nil, err
+	}
+
+	return conn, nil
+}