app.py

from flask import Flask, request, jsonify, Response, make_response
import requests
import threading
import time
import os

app = Flask(__name__)

MODEL = 'claude-3-5-sonnet@20240620'
PROJECT_ID = os.getenv('PROJECT_ID')
CLIENT_ID = os.getenv('CLIENT_ID')
CLIENT_SECRET = os.getenv('CLIENT_SECRET')
REFRESH_TOKEN = os.getenv('REFRESH_TOKEN')
API_KEY = os.getenv('API_KEY')
TOKEN_URL = 'https://www.googleapis.com/oauth2/v4/token'

token_cache = {
    'access_token': '',
    'expiry': 0,
    'refresh_promise': None
}

def get_access_token():
    now = time.time()

    if token_cache['access_token'] and now < token_cache['expiry'] - 120:
        return token_cache['access_token']

    if token_cache['refresh_promise']:
        token_cache['refresh_promise'].join()
        return token_cache['access_token']

    def refresh_token():
        try:
            response = requests.post(TOKEN_URL, json={
                'client_id': CLIENT_ID,
                'client_secret': CLIENT_SECRET,
                'refresh_token': REFRESH_TOKEN,
                'grant_type': 'refresh_token'
            })
            data = response.json()
            token_cache['access_token'] = data['access_token']
            token_cache['expiry'] = now + data['expires_in']
        finally:
            token_cache['refresh_promise'] = None

    token_cache['refresh_promise'] = threading.Thread(target=refresh_token)
    token_cache['refresh_promise'].start()
    token_cache['refresh_promise'].join()
    return token_cache['access_token']

def get_location():
    current_seconds = time.localtime().tm_sec
    return 'europe-west1' if current_seconds < 30 else 'us-east5'

def construct_api_url(location):
    return f'https://{location}-aiplatform.googleapis.com/v1/projects/{PROJECT_ID}/locations/{location}/publishers/anthropic/models/{MODEL}:streamRawPredict'

@app.route('/ai/v1/messages', methods=['POST', 'OPTIONS'])
def handle_request():
    if request.method == 'OPTIONS':
        return handle_options()

    api_key = request.headers.get('x-api-key')
    if api_key != API_KEY:
        error_response = make_response(jsonify({
            'type': 'error',
            'error': {
                'type': 'permission_error',
                'message': 'Your API key does not have permission to use the specified resource.'
            }
        }), 403)
        error_response.headers['Access-Control-Allow-Origin'] = '*'
        error_response.headers['Access-Control-Allow-Methods'] = 'POST, GET, OPTIONS, DELETE, HEAD'
        error_response.headers['Access-Control-Allow-Headers'] = 'Content-Type, Authorization, x-api-key, anthropic-version, model'
        return error_response

    access_token = get_access_token()
    location = get_location()
    api_url = construct_api_url(location)

    request_body = request.json

    if 'anthropic_version' in request_body:
        del request_body['anthropic_version']
    if 'model' in request_body:
        del request_body['model']

    request_body['anthropic_version'] = 'vertex-2023-10-16'

    headers = {
        'Authorization': f'Bearer {access_token}',
        'Content-Type': 'application/json; charset=utf-8'
    }

    response = requests.post(api_url, headers=headers, json=request_body)
    modified_response = make_response(response.content, response.status_code)
    modified_response.headers['Access-Control-Allow-Origin'] = '*'
    modified_response.headers['Access-Control-Allow-Methods'] = 'POST, GET, OPTIONS'
    modified_response.headers['Access-Control-Allow-Headers'] = 'Content-Type, Authorization, x-api-key, anthropic-version, model'

    return modified_response

def handle_options():
    headers = {
        'Access-Control-Allow-Origin': '*',
        'Access-Control-Allow-Methods': 'POST, GET, OPTIONS',
        'Access-Control-Allow-Headers': 'Content-Type, Authorization, x-api-key, anthropic-version, model'
    }
    return '', 204, headers

if __name__ == '__main__':
    app.run(port=8080)