gemini_proxy.py

import os
import json
import requests
import re
import uvicorn
import base64
from datetime import datetime
from fastapi import FastAPI, Request, Response, HTTPException, Depends
from fastapi.responses import StreamingResponse
from fastapi.security import HTTPBasic, HTTPBasicCredentials
from http.server import BaseHTTPRequestHandler, HTTPServer
from urllib.parse import urlparse, parse_qs
import ijson
from dotenv import load_dotenv

from google.oauth2.credentials import Credentials
from google_auth_oauthlib.flow import Flow
from google.auth.transport.requests import Request as GoogleAuthRequest

# Load environment variables from .env file
load_dotenv()

# --- Configuration ---
CLIENT_ID = "681255809395-oo8ft2oprdrnp9e3aqf6av3hmdib135j.apps.googleusercontent.com"
CLIENT_SECRET = "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"
SCOPES = [
    "https://www.googleapis.com/auth/cloud-platform",
    "https://www.googleapis.com/auth/userinfo.email",
    "https://www.googleapis.com/auth/userinfo.profile",
    "openid",
]
GEMINI_DIR = os.path.dirname(os.path.abspath(__file__))  # Same directory as the script
CREDENTIAL_FILE = os.path.join(GEMINI_DIR, "oauth_creds.json")
CODE_ASSIST_ENDPOINT = "https://cloudcode-pa.googleapis.com"
GEMINI_PORT = int(os.getenv("GEMINI_PORT", "8888"))  # Default to 8888 if not set
GEMINI_AUTH_PASSWORD = os.getenv("GEMINI_AUTH_PASSWORD", "123456")  # Default password

# --- Global State ---
credentials = None
user_project_id = None

app = FastAPI()
security = HTTPBasic()

def authenticate_user(request: Request):
    """Authenticate the user with multiple methods."""
    # Check for API key in query parameters first (for Gemini client compatibility)
    api_key = request.query_params.get("key")
    if api_key and api_key == GEMINI_AUTH_PASSWORD:
        return "api_key_user"
    
    # Check for API key in Authorization header (Bearer token format)
    auth_header = request.headers.get("authorization", "")
    if auth_header.startswith("Bearer ") and auth_header[7:] == GEMINI_AUTH_PASSWORD:
        return "bearer_user"
    
    # Check for HTTP Basic Authentication
    if auth_header.startswith("Basic "):
        try:
            encoded_credentials = auth_header[6:]
            decoded_credentials = base64.b64decode(encoded_credentials).decode('utf-8')
            username, password = decoded_credentials.split(':', 1)
            if password == GEMINI_AUTH_PASSWORD:
                return username
        except Exception:
            pass
    
    # If none of the authentication methods work
    raise HTTPException(
        status_code=401,
        detail="Invalid authentication credentials. Use HTTP Basic Auth, Bearer token, or 'key' query parameter.",
        headers={"WWW-Authenticate": "Basic"},
    )

# Helper class to adapt a generator of bytes into a file-like object
# that ijson can read from.
class _GeneratorStream:
    def __init__(self, generator):
        self.generator = generator
        self.buffer = b''

    def read(self, size=-1):
        # This read implementation is crucial for streaming.
        # It must not block to read the entire stream if size is -1.
        if size == -1:
            # If asked to read all, return what's in the buffer and get one more chunk.
            try:
                self.buffer += next(self.generator)
            except StopIteration:
                pass
            data = self.buffer
            self.buffer = b''
            return data

        # Otherwise, read from the generator until we have enough bytes.
        while len(self.buffer) < size:
            try:
                self.buffer += next(self.generator)
            except StopIteration:
                # Generator is exhausted.
                break
        
        data = self.buffer[:size]
        self.buffer = self.buffer[size:]
        return data

class _OAuthCallbackHandler(BaseHTTPRequestHandler):
    auth_code = None
    def do_GET(self):
        query_components = parse_qs(urlparse(self.path).query)
        code = query_components.get("code", [None])[0]
        if code:
            _OAuthCallbackHandler.auth_code = code
            self.send_response(200)
            self.send_header("Content-type", "text/html")
            self.end_headers()
            self.wfile.write(b"<h1>Authentication successful!</h1><p>You can close this window and restart the proxy.</p>")
        else:
            self.send_response(400)
            self.send_header("Content-type", "text/html")
            self.end_headers()
            self.wfile.write(b"<h1>Authentication failed.</h1><p>Please try again.</p>")

def get_user_project_id(creds):
    """Gets the user's project ID from environment variable, cache, or by probing the API."""
    global user_project_id
    if user_project_id:
        return user_project_id

    # First, check for environment variable override
    env_project_id = os.getenv("GEMINI_PROJECT_ID")
    if env_project_id:
        user_project_id = env_project_id
        print(f"Using project ID from environment variable: {user_project_id}")
        # Save the environment project ID to cache for consistency
        save_credentials(creds, user_project_id)
        return user_project_id

    # Second, try to load project ID from credential file
    if os.path.exists(CREDENTIAL_FILE):
        try:
            with open(CREDENTIAL_FILE, "r") as f:
                creds_data = json.load(f)
                cached_project_id = creds_data.get("project_id")
                if cached_project_id:
                    user_project_id = cached_project_id
                    print(f"Loaded project ID from cache: {user_project_id}")
                    return user_project_id
        except Exception as e:
            print(f"Could not load project ID from cache: {e}")

    # If not found in environment or cache, probe for it
    print("Project ID not found in environment or cache. Probing for user project ID...")
    headers = {
        "Authorization": f"Bearer {creds.token}",
        "Content-Type": "application/json",
    }
    
    probe_payload = {
        "cloudaicompanionProject": "gcp-project",
        "metadata": {
            "ideType": "VSCODE",
            "pluginType": "GEMINI"
        }
    }

    try:
        resp = requests.post(
            f"{CODE_ASSIST_ENDPOINT}/v1internal:loadCodeAssist",
            data=json.dumps(probe_payload),
            headers=headers,
        )
        resp.raise_for_status()
        data = resp.json()
        user_project_id = data.get("cloudaicompanionProject")
        if not user_project_id:
            raise ValueError("Could not find 'cloudaicompanionProject' in loadCodeAssist response.")
        print(f"Successfully fetched user project ID: {user_project_id}")
        
        # Save the project ID to the credential file for future use
        save_credentials(creds, user_project_id)
        print("Project ID saved to credential file for future use.")
        
        return user_project_id
    except requests.exceptions.HTTPError as e:
        print(f"Error fetching project ID: {e.response.text}")
        raise

def save_credentials(creds, project_id=None):
    os.makedirs(GEMINI_DIR, exist_ok=True)
    creds_data = {
        "access_token": creds.token,
        "refresh_token": creds.refresh_token,
        "scope": " ".join(creds.scopes),
        "token_type": "Bearer",
        "expiry_date": creds.expiry.isoformat() if creds.expiry else None,
    }
    
    # If project_id is provided, save it; otherwise preserve existing project_id
    if project_id:
        creds_data["project_id"] = project_id
    elif os.path.exists(CREDENTIAL_FILE):
        try:
            with open(CREDENTIAL_FILE, "r") as f:
                existing_data = json.load(f)
                if "project_id" in existing_data:
                    creds_data["project_id"] = existing_data["project_id"]
        except Exception:
            pass  # If we can't read existing file, just continue without project_id
    
    with open(CREDENTIAL_FILE, "w") as f:
        json.dump(creds_data, f)

def get_credentials():
    """Loads credentials from cache or initiates the OAuth 2.0 flow."""
    global credentials

    if credentials:
        if credentials.valid:
            return credentials
        if credentials.expired and credentials.refresh_token:
            print("Refreshing expired credentials...")
            try:
                credentials.refresh(GoogleAuthRequest())
                save_credentials(credentials)
                print("Credentials refreshed successfully.")
                return credentials
            except Exception as e:
                print(f"Could not refresh token: {e}. Attempting to load from file.")
    
    if os.path.exists(CREDENTIAL_FILE):
        try:
            with open(CREDENTIAL_FILE, "r") as f:
                creds_data = json.load(f)

            # Load project ID if available
            global user_project_id
            cached_project_id = creds_data.get("project_id")
            if cached_project_id:
                user_project_id = cached_project_id
                print(f"Loaded project ID from credential file: {user_project_id}")

            expiry = None
            expiry_str = creds_data.get("expiry_date")
            if expiry_str:
                if not isinstance(expiry_str, str) or not expiry_str.strip():
                     expiry = None
                elif expiry_str.endswith('Z'):
                    expiry_str = expiry_str[:-1] + '+00:00'
                    expiry = datetime.fromisoformat(expiry_str)
                else:
                    expiry = datetime.fromisoformat(expiry_str)

            credentials = Credentials(
                token=creds_data.get("access_token"),
                refresh_token=creds_data.get("refresh_token"),
                token_uri="https://oauth2.googleapis.com/token",
                client_id=CLIENT_ID,
                client_secret=CLIENT_SECRET,
                scopes=SCOPES,
                expiry=expiry
            )
            
            if credentials.expired and credentials.refresh_token:
                print("Loaded credentials from file are expired. Refreshing...")
                credentials.refresh(GoogleAuthRequest())
                save_credentials(credentials)

            print("Successfully loaded credentials from cache.")
            return credentials
        except Exception as e:
            print(f"Could not load cached credentials: {e}. Starting new login.")

    client_config = {
        "installed": {
            "client_id": CLIENT_ID,
            "client_secret": CLIENT_SECRET,
            "auth_uri": "https://accounts.google.com/o/oauth2/auth",
            "token_uri": "https://oauth2.googleapis.com/token",
        }
    }
    flow = Flow.from_client_config(
        client_config, scopes=SCOPES, redirect_uri="http://localhost:8080"
    )
    auth_url, _ = flow.authorization_url(access_type="offline", prompt="consent")
    print(f"\nPlease open this URL in your browser to log in:\n{auth_url}\n")
    
    server = HTTPServer(("", 8080), _OAuthCallbackHandler)
    server.handle_request()
    
    auth_code = _OAuthCallbackHandler.auth_code
    if not auth_code:
        print("Failed to retrieve authorization code.")
        return None

    flow.fetch_token(code=auth_code)
    credentials = flow.credentials
    save_credentials(credentials)
    print("Authentication successful! Credentials saved.")
    return credentials


@app.post("/{full_path:path}")
async def proxy_request(request: Request, full_path: str, username: str = Depends(authenticate_user)):
    creds = get_credentials()
    if not creds:
        return Response(content="Authentication failed. Please restart the proxy to log in.", status_code=500)

    # Only check if credentials are properly formed and not expired locally
    if not creds.valid:
        if creds.expired and creds.refresh_token:
            print("Credentials expired locally. Refreshing...")
            try:
                creds.refresh(GoogleAuthRequest())
                save_credentials(creds)
                print("Credentials refreshed successfully.")
            except Exception as e:
                print(f"Could not refresh token during request: {e}")
                return Response(content="Token refresh failed. Please restart the proxy to re-authenticate.", status_code=500)
        else:
            print("Credentials are invalid locally and cannot be refreshed.")
            return Response(content="Invalid credentials. Please restart the proxy to re-authenticate.", status_code=500)

    proj_id = get_user_project_id(creds)
    if not proj_id:
        return Response(content="Failed to get user project ID.", status_code=500)

    post_data = await request.body()
    path = f"/{full_path}"
    model_name_from_url = None
    action = None

    model_match = re.match(r"/(v\d+(?:beta)?)/models/([^:]+):(\w+)", path)

    is_streaming = False
    if model_match:
        model_name_from_url = model_match.group(2)
        action = model_match.group(3)
        target_url = f"{CODE_ASSIST_ENDPOINT}/v1internal:{action}"
        if "stream" in action.lower():
            is_streaming = True
    else:
        target_url = f"{CODE_ASSIST_ENDPOINT}{path}"
    
    # Remove authentication query parameters before forwarding to Google API
    query_params = dict(request.query_params)
    # Remove our authentication parameters
    query_params.pop("key", None)
    
    # Add remaining query parameters to target URL if any
    if query_params:
        from urllib.parse import urlencode
        target_url += "?" + urlencode(query_params)

    try:
        incoming_json = json.loads(post_data)
        final_model = model_name_from_url if model_match else incoming_json.get("model")
        
        # Set default safety settings to BLOCK_NONE if not specified by user
        safety_settings = incoming_json.get("safetySettings")
        if not safety_settings:
            safety_settings = [
                {"category": "HARM_CATEGORY_HARASSMENT", "threshold": "BLOCK_NONE"},
                {"category": "HARM_CATEGORY_HATE_SPEECH", "threshold": "BLOCK_NONE"},
                {"category": "HARM_CATEGORY_SEXUALLY_EXPLICIT", "threshold": "BLOCK_NONE"},
                {"category": "HARM_CATEGORY_DANGEROUS_CONTENT", "threshold": "BLOCK_NONE"},
                {"category": "HARM_CATEGORY_CIVIC_INTEGRITY", "threshold": "BLOCK_NONE"}
            ]
        
        structured_payload = {
            "model": final_model,
            "project": proj_id,
            "request": {
                "contents": incoming_json.get("contents"),
                "systemInstruction": incoming_json.get("systemInstruction"),
                "cachedContent": incoming_json.get("cachedContent"),
                "tools": incoming_json.get("tools"),
                "toolConfig": incoming_json.get("toolConfig"),
                "safetySettings": safety_settings,
                "generationConfig": incoming_json.get("generationConfig"),
            },
        }
        structured_payload["request"] = {
            k: v
            for k, v in structured_payload["request"].items()
            if v is not None
        }
        final_post_data = json.dumps(structured_payload)
    except (json.JSONDecodeError, AttributeError):
        final_post_data = post_data

    headers = {
        "Authorization": f"Bearer {creds.token}",
        "Content-Type": "application/json",
        # We remove 'Accept-Encoding' to allow the server to send gzip,
        # which it seems to stream correctly. We will decompress on the fly.
    }

    if is_streaming:
        async def stream_generator():
            try:
                print(f"[STREAM] Starting streaming request to: {target_url}")
                print(f"[STREAM] Request payload size: {len(final_post_data)} bytes")
                
                # Make the initial streaming request
                resp = requests.post(target_url, data=final_post_data, headers=headers, stream=True)
                print(f"[STREAM] Response status: {resp.status_code}")
                print(f"[STREAM] Response headers: {dict(resp.headers)}")
                
                # If we get a 401, try refreshing the token and retry once
                if resp.status_code == 401 and creds.refresh_token:
                    print("[STREAM] Received 401 from Google API. Attempting to refresh token and retry...")
                    resp.close()  # Close the failed response
                    try:
                        creds.refresh(GoogleAuthRequest())
                        save_credentials(creds)
                        print("[STREAM] Token refreshed successfully. Retrying streaming request...")
                        
                        # Update headers with new token and retry
                        headers["Authorization"] = f"Bearer {creds.token}"
                        resp = requests.post(target_url, data=final_post_data, headers=headers, stream=True)
                        print(f"[STREAM] Retry request status: {resp.status_code}")
                    except Exception as e:
                        print(f"[STREAM] Could not refresh token after 401 error: {e}")
                        error_message = json.dumps({"error": {"message": "Token refresh failed after 401 error. Please restart the proxy to re-authenticate."}})
                        yield f"data: {error_message}\n\n"
                        return
                
                with resp:
                    resp.raise_for_status()
                    
                    buffer = ""
                    brace_count = 0
                    in_array = False
                    chunk_count = 0
                    total_bytes = 0
                    objects_yielded = 0
                    
                    print(f"[STREAM] Starting to process chunks...")
                    
                    for chunk in resp.iter_content(chunk_size=1024):
                        if isinstance(chunk, bytes):
                            chunk = chunk.decode('utf-8', errors='replace')
                        chunk_count += 1
                        chunk_size = len(chunk) if chunk else 0
                        total_bytes += chunk_size
                        
                        buffer += chunk
                        
                        # Process complete JSON objects from the buffer
                        processing_iterations = 0
                        while buffer:
                            processing_iterations += 1
                            if processing_iterations > 100:  # Prevent infinite loops
                                break
                                
                            buffer = buffer.lstrip()
                            
                            if not buffer:
                                break
                                                                
                            # Handle array start
                            if buffer.startswith('[') and not in_array:
                                buffer = buffer[1:].lstrip()
                                in_array = True
                                continue
                            
                            # Handle array end
                            if buffer.startswith(']'):
                                break
                                
                            # Skip commas between objects
                            if buffer.startswith(','):
                                buffer = buffer[1:].lstrip()
                                continue
                            
                            # Look for complete JSON objects
                            if buffer.startswith('{'):
                                brace_count = 0
                                in_string = False
                                escape_next = False
                                end_pos = -1
                                
                                for i, char in enumerate(buffer):
                                    if escape_next:
                                        escape_next = False
                                        continue
                                    if char == '\\':
                                        escape_next = True
                                        continue
                                    if char == '"' and not escape_next:
                                        in_string = not in_string
                                        continue
                                    if not in_string:
                                        if char == '{':
                                            brace_count += 1
                                        elif char == '}':
                                            brace_count -= 1
                                            if brace_count == 0:
                                                end_pos = i + 1
                                                break
                                
                                if end_pos > 0:
                                    # Found complete JSON object
                                    json_str = buffer[:end_pos]
                                    buffer = buffer[end_pos:].lstrip()
                                    
                                    
                                    try:
                                        obj = json.loads(json_str)
                                        
                                        if "response" in obj:
                                            response_chunk = obj["response"]
                                            objects_yielded += 1
                                            response_json = json.dumps(response_chunk)
                                            yield f"data: {response_json}\n\n"
                                    except json.JSONDecodeError as e:
                                        continue
                                else:
                                    # Incomplete object, wait for more data
                                    break
                            else:
                                # Skip unexpected characters
                                buffer = buffer[1:]
                    
            except requests.exceptions.RequestException as e:
                print(f"Error during streaming request: {e}")
                error_message = json.dumps({"error": {"message": f"Upstream request failed: {e}"}})
                yield f"data: {error_message}\n\n"
            except Exception as e:
                print(f"An unexpected error occurred during streaming: {e}")
                error_message = json.dumps({"error": {"message": f"An unexpected error occurred: {e}"}})
                yield f"data: {error_message}\n\n"

        return StreamingResponse(stream_generator(), media_type="text/event-stream")
    else:
        # Make the request
        resp = requests.post(target_url, data=final_post_data, headers=headers)
        
        # If we get a 401, try refreshing the token and retry once
        if resp.status_code == 401 and creds.refresh_token:
            print("Received 401 from Google API. Attempting to refresh token and retry...")
            try:
                creds.refresh(GoogleAuthRequest())
                save_credentials(creds)
                print("Token refreshed successfully. Retrying request...")
                
                # Update headers with new token and retry
                headers["Authorization"] = f"Bearer {creds.token}"
                resp = requests.post(target_url, data=final_post_data, headers=headers)
                print(f"Retry request status: {resp.status_code}")
            except Exception as e:
                print(f"Could not refresh token after 401 error: {e}")
                return Response(content="Token refresh failed after 401 error. Please restart the proxy to re-authenticate.", status_code=500)
        
        if resp.status_code == 200:
            try:
                google_api_response = resp.json()
                # The actual response is nested under the "response" key
                standard_gemini_response = google_api_response.get("response")
                # The standard client expects a list containing the response object
                return Response(content=json.dumps([standard_gemini_response]), status_code=200, media_type="application/json")
            except (json.JSONDecodeError, AttributeError) as e:
                print(f"Error converting to standard Gemini format: {e}")
                # Fallback to sending the original content if conversion fails
                return Response(content=resp.content, status_code=resp.status_code, media_type=resp.headers.get("Content-Type"))
        else:
            return Response(content=resp.content, status_code=resp.status_code, media_type=resp.headers.get("Content-Type"))


if __name__ == "__main__":
    print("Initializing credentials...")
    creds = get_credentials()
    if creds:
        get_user_project_id(creds)
        print(f"\nStarting Gemini proxy server on http://localhost:{GEMINI_PORT}")
        print("Send your Gemini API requests to this address.")
        print(f"Authentication required - Password: {GEMINI_AUTH_PASSWORD}")
        print("Use HTTP Basic Authentication with any username and the password above.")
        uvicorn.run(app, host="0.0.0.0", port=GEMINI_PORT)
    else:
        print("\nCould not obtain credentials. Please authenticate and restart the server.")