Charter Overview

from typing import Annotated

from pydantic import BaseModel
from charter import Body, EmailContent, Format, oauth_tool_factory
from charter.auth import EnvTokenProvider


# 1. Describe the args the LLM fills in
class SendEmail(BaseModel):
    raw: Annotated[
        EmailContent, Body(envelop=True), Format("rfc822_base64")
    ]


# 2. Say where the request goes
gmail = oauth_tool_factory(
    base_url="https://gmail.googleapis.com/",
    provider="google",
    credential_provider=EnvTokenProvider("GOOGLE_ACCESS_TOKEN"),
)

send_email = gmail(
    name="send_email",
    description="Send an email.",
    method="POST",
    url_template="gmail/v1/users/me/messages/send",
    args_schema=SendEmail,
)

await send_email.ainvoke(
    raw={"to": "ada@example.com", "subject": "Hi", "body": "Hello"}
)

# 1. Install google-auth, google-auth-oauthlib, google-api-python-client
import base64
import os.path
from email.message import EmailMessage

from google.auth.transport.requests import Request
from google.oauth2.credentials import Credentials
from google_auth_oauthlib.flow import InstalledAppFlow
from googleapiclient.discovery import build
from googleapiclient.errors import HttpError

SCOPES = ["https://www.googleapis.com/auth/gmail.send"]


def send_email(to: str, subject: str, body: str) -> str:
    """Send an email."""
    # 2. Run Google's OAuth flow
    creds = None
    if os.path.exists("token.json"):
        creds = Credentials.from_authorized_user_file("token.json", SCOPES)
    if not creds or not creds.valid:
        # 3. Refresh the token and persist it
        if creds and creds.expired and creds.refresh_token:
            creds.refresh(Request())
        else:
            flow = InstalledAppFlow.from_client_secrets_file(
                "credentials.json", SCOPES
            )
            creds = flow.run_local_server(port=0)
        with open("token.json", "w") as token:
            token.write(creds.to_json())

    try:
        # 4. Build the API client
        service = build("gmail", "v1", credentials=creds)

        # 5. Assemble the MIME document
        message = EmailMessage()
        message.set_content(body)
        message["To"] = to
        message["Subject"] = subject

        # 6. Encode, wrap in Gmail's envelope, send
        encoded = base64.urlsafe_b64encode(message.as_bytes()).decode()
        sent = (
            service.users()
            .messages()
            .send(userId="me", body={"raw": encoded})
            .execute()
        )
        return f'Message Id: {sent["id"]}'
    except HttpError as error:
        return f"An error occurred: {error}"


send_email(
    **{"to": "ada@example.com", "subject": "Hi", "body": "Hello"}
)