add oauth helpers

src/openrouter/utils/__init__.py

@@ -53,9 +53,25 @@ if TYPE_CHECKING:
         cast_partial,
     )
     from .logger import Logger, get_body_content, get_default_logger
+    from .oauth_create_sha256_code_challenge import (
+        oauth_create_sha256_code_challenge,
+        CreateSHA256CodeChallengeRequest,
+        CreateSHA256CodeChallengeResponse,
+    )
+    from .oauth_create_authorization_url import (
+        oauth_create_authorization_url,
+        CreateAuthorizationUrlRequest,
+        CreateAuthorizationUrlRequestBase,
+        CreateAuthorizationUrlRequestWithPKCE,
+    )
 
 __all__ = [
     "BackoffStrategy",
+    "CreateAuthorizationUrlRequest",
+    "CreateAuthorizationUrlRequestBase",
+    "CreateAuthorizationUrlRequestWithPKCE",
+    "CreateSHA256CodeChallengeRequest",
+    "CreateSHA256CodeChallengeResponse",
     "FieldMetadata",
     "find_metadata",
     "FormMetadata",
@@ -78,6 +94,8 @@ __all__ = [
     "match_status_codes",
     "match_response",
     "MultipartFormMetadata",
+    "oauth_create_authorization_url",
+    "oauth_create_sha256_code_challenge",
     "OpenEnumMeta",
     "PathParamMetadata",
     "QueryParamMetadata",
@@ -110,6 +128,11 @@ __all__ = [
 
 _dynamic_imports: dict[str, str] = {
     "BackoffStrategy": ".retries",
+    "CreateAuthorizationUrlRequest": ".oauth_create_authorization_url",
+    "CreateAuthorizationUrlRequestBase": ".oauth_create_authorization_url",
+    "CreateAuthorizationUrlRequestWithPKCE": ".oauth_create_authorization_url",
+    "CreateSHA256CodeChallengeRequest": ".oauth_create_sha256_code_challenge",
+    "CreateSHA256CodeChallengeResponse": ".oauth_create_sha256_code_challenge",
     "FieldMetadata": ".metadata",
     "find_metadata": ".metadata",
     "FormMetadata": ".metadata",
@@ -132,6 +155,8 @@ _dynamic_imports: dict[str, str] = {
     "match_status_codes": ".values",
     "match_response": ".values",
     "MultipartFormMetadata": ".metadata",
+    "oauth_create_authorization_url": ".oauth_create_authorization_url",
+    "oauth_create_sha256_code_challenge": ".oauth_create_sha256_code_challenge",
     "OpenEnumMeta": ".enums",
     "PathParamMetadata": ".metadata",
     "QueryParamMetadata": ".metadata",

src/openrouter/utils/oauth_create_authorization_url.py

@@ -0,0 +1,95 @@
+"""Generate OAuth2 authorization URL"""
+
+from dataclasses import dataclass
+from typing import TYPE_CHECKING, Literal, Optional, Union
+from urllib.parse import urlencode, urlparse
+
+if TYPE_CHECKING:
+    from openrouter.sdk import OpenRouter
+
+
+@dataclass
+class CreateAuthorizationUrlRequestBase:
+    """Base request parameters for creating an authorization URL"""
+    callback_url: Union[str, "urlparse"]
+    limit: Optional[float] = None
+
+
+@dataclass
+class CreateAuthorizationUrlRequestWithPKCE(CreateAuthorizationUrlRequestBase):
+    """Request parameters with PKCE for creating an authorization URL"""
+    code_challenge_method: Literal["S256", "plain"]
+    code_challenge: str
+
+
+# Union type for request - either with PKCE or without
+CreateAuthorizationUrlRequest = Union[
+    CreateAuthorizationUrlRequestWithPKCE,
+    CreateAuthorizationUrlRequestBase,
+]
+
+
+def _get_server_url(client: "OpenRouter") -> str:
+    """
+    Get the server URL from the client configuration
+
+    Args:
+        client: OpenRouter client instance
+
+    Returns:
+        The server URL
+
+    Raises:
+        ValueError: If no server URL is configured
+    """
+    server_url, _ = client.sdk_configuration.get_server_details()
+    if not server_url:
+        raise ValueError("No server URL configured")
+    return server_url
+
+
+def oauth_create_authorization_url(
+    client: "OpenRouter",
+    params: CreateAuthorizationUrlRequest,
+) -> str:
+    """
+    Generate an OAuth2 authorization URL
+
+    Generates a URL to redirect users to for authorizing your application. The
+    URL includes the provided callback URL and, if applicable, the code
+    challenge parameters for PKCE.
+
+    Args:
+        client: OpenRouter client instance
+        params: Request parameters including callback URL and optional PKCE parameters
+
+    Returns:
+        The authorization URL as a string
+
+    Raises:
+        ValueError: If no server URL is configured or parameters are invalid
+
+    See Also:
+        - https://openrouter.ai/docs/use-cases/oauth-pkce
+    """
+    base_url = _get_server_url(client)
+
+    # Build the auth URL
+    auth_url = f"{base_url}/auth"
+
+    # Build query parameters
+    query_params = {
+        "callback_url": str(params.callback_url),
+    }
+
+    # Add PKCE parameters if present
+    if isinstance(params, CreateAuthorizationUrlRequestWithPKCE):
+        query_params["code_challenge"] = params.code_challenge
+        query_params["code_challenge_method"] = params.code_challenge_method
+
+    # Add limit if present
+    if params.limit is not None:
+        query_params["limit"] = str(params.limit)
+
+    # Construct final URL with query parameters
+    return f"{auth_url}?{urlencode(query_params)}"

src/openrouter/utils/oauth_create_sha256_code_challenge.py

@@ -0,0 +1,120 @@
+"""Generate SHA-256 code challenge for PKCE OAuth flow"""
+
+import base64
+import hashlib
+import re
+import secrets
+from dataclasses import dataclass
+from typing import Optional
+
+
+@dataclass
+class CreateSHA256CodeChallengeRequest:
+    """
+    Request parameters for creating a SHA-256 code challenge.
+
+    If not provided, a random code verifier will be generated.
+    If provided, must be 43-128 characters and contain only unreserved
+    characters [A-Za-z0-9-._~] per RFC 7636.
+    """
+    code_verifier: Optional[str] = None
+
+
+@dataclass
+class CreateSHA256CodeChallengeResponse:
+    """Response containing the code challenge and verifier"""
+    code_challenge: str
+    code_verifier: str
+
+
+def _array_buffer_to_base64_url(data: bytes) -> str:
+    """
+    Convert bytes to base64url encoding (RFC 4648)
+
+    Args:
+        data: Bytes to encode
+
+    Returns:
+        Base64url encoded string
+    """
+    return base64.urlsafe_b64encode(data).rstrip(b"=").decode("ascii")
+
+
+def _generate_code_verifier() -> str:
+    """
+    Generate a cryptographically random code verifier per RFC 7636
+
+    RFC 7636 recommends 32 octets of random data, base64url encoded = 43 chars
+
+    Returns:
+        A random code verifier string
+    """
+    random_bytes = secrets.token_bytes(32)
+    return _array_buffer_to_base64_url(random_bytes)
+
+
+def _validate_code_verifier(code_verifier: str) -> None:
+    """
+    Validate code verifier according to RFC 7636
+
+    Args:
+        code_verifier: The code verifier to validate
+
+    Raises:
+        ValueError: If the code verifier is invalid
+    """
+    if len(code_verifier) < 43:
+        raise ValueError("Code verifier must be at least 43 characters")
+    if len(code_verifier) > 128:
+        raise ValueError("Code verifier must be at most 128 characters")
+    if not re.match(r"^[A-Za-z0-9\-._~]+$", code_verifier):
+        raise ValueError(
+            "Code verifier must only contain unreserved characters: [A-Za-z0-9-._~]"
+        )
+
+
+def oauth_create_sha256_code_challenge(
+    params: Optional[CreateSHA256CodeChallengeRequest] = None,
+) -> CreateSHA256CodeChallengeResponse:
+    """
+    Generate a SHA-256 code challenge for PKCE
+
+    Generates a SHA-256 code challenge and corresponding code verifier for use
+    in the PKCE extension to OAuth2. If no code verifier is provided, a random
+    one will be generated according to RFC 7636 (32 random bytes, base64url
+    encoded). If a code verifier is provided, it must be 43-128 characters and
+    contain only unreserved characters [A-Za-z0-9-._~].
+
+    Args:
+        params: Optional request parameters. If None, a random code verifier will be generated.
+
+    Returns:
+        CreateSHA256CodeChallengeResponse containing the code challenge and verifier
+
+    Raises:
+        ValueError: If the provided code verifier is invalid
+
+    See Also:
+        - https://openrouter.ai/docs/use-cases/oauth-pkce
+        - https://datatracker.ietf.org/doc/html/rfc7636
+    """
+    if params is None:
+        params = CreateSHA256CodeChallengeRequest()
+
+    code_verifier = params.code_verifier
+    if code_verifier is None:
+        code_verifier = _generate_code_verifier()
+    else:
+        _validate_code_verifier(code_verifier)
+
+    # Generate SHA-256 hash
+    data = code_verifier.encode("utf-8")
+    hash_digest = hashlib.sha256(data).digest()
+
+    # Convert hash to base64url
+    code_challenge = _array_buffer_to_base64_url(hash_digest)
+
+    return CreateSHA256CodeChallengeResponse(
+        code_challenge=code_challenge,
+        code_verifier=code_verifier,
+    )