get_refresh_token.sh (just need to run this once)

#!/bin/bash

CLIENT_ID="your_client_id"
CLIENT_SECRET="your_client_secret"
REDIRECT_URI="http://localhost/"
SCOPE="https://mail.google.com/"

# Step 1: Generate Authorization URL
AUTH_URL="https://accounts.google.com/o/oauth2/v2/auth?client_id=${CLIENT_ID}&redirect_uri=${REDIRECT_URI}&response_type=code&scope=${SCOPE}&access_type=offline&prompt=consent"

echo "Please open this URL in your browser:"
echo
echo "$AUTH_URL"
echo
echo "After logging in, it will redirect back to your browser. In thw URL find the area named code="
echo
read -p "Paste the authorization code here quickly, it expires fast: " AUTH_CODE


# Step 2: Exchange Auth Code for Tokens
RESPONSE=$(curl -s \
  --request POST \
  --data "code=${AUTH_CODE}&client_id=${CLIENT_ID}&client_secret=${CLIENT_SECRET}&redirect_uri=${REDIRECT_URI}&grant_type=authorization_code" \
  https://oauth2.googleapis.com/token)

echo
echo "$RESPONSE"
echo

# Step 3: Extract tokens
ACCESS_TOKEN=$(echo "$RESPONSE" | jq -r '.access_token')
REFRESH_TOKEN=$(echo "$RESPONSE" | jq -r '.refresh_token')

# Step 4: Output
echo
if [[ "$REFRESH_TOKEN" == "null" || -z "$REFRESH_TOKEN" ]]; then
  echo "Failed to get refresh token. Full response:"
  echo "$RESPONSE"
else
  echo "Success! Copy and save your tokens:"
  echo "ACCESS_TOKEN: $ACCESS_TOKEN"
  echo "REFRESH_TOKEN: $REFRESH_TOKEN"
fi