#!/bin/bash -e

echo "macOS Helper to configure SSH Key to use with GitHub"
echo "based off of instructions reported at:"
echo "https://docs.github.com/en/github/authenticating-to-github/adding-a-new-ssh-key-to-your-github-account"
echo

if [[ "$OSTYPE" != "darwin"* ]]; then
  echo "This script is designed for macOS only..."
  echo "exiting"
  exit 1
fi

echo "Checking existing ed25519 SSH key..."

if [ ! -f "$HOME/.ssh/id_ed25519" ]; then
  echo "You don't have it, generating it for you..."
  echo
  EMAIL=$(git config --global user.email)
  echo "Detected email from git config: $EMAIL"
  echo
  echo "IF IT'S NOT CORRECT, PLEASE HIT CONTROL + C TO EXIT THIS SCRIPT"
  echo "AND PROPERLY CONFIGURE YOUR GIT EMAIL WITH THIS COMMAND:"
  echo "git config --global user.email \"youremail@provider.com\""
  echo
  echo "When prompted where to save the certificate, press ENTER"
  echo "and then press ENTER two more times when asked to put in a password"
  echo
  ssh-keygen -t ed25519 -C "$EMAIL" || true
else
  echo "Good! You have it!"
fi

echo
echo "Starting SSH Agent in the background"
eval "$(ssh-agent -s)"

if [ ! -f "$HOME/.ssh/config" ]; then
  echo
  echo "Creating new SSH config"
  touch "$HOME/.ssh/config"
else
  echo "Using existing SSH config"
fi

if grep -q "IdentityFile ~/.ssh/id_ed25519" "$HOME/.ssh/config"; then
    echo "SSH Config already correct!"
else
  echo "Adding the configuration to SSH Config"

  echo "Host *" >> "$HOME/.ssh/config"
  echo "  AddKeysToAgent yes" >> "$HOME/.ssh/config"
  echo "  IdentityFile ~/.ssh/id_ed25519" >> "$HOME/.ssh/config"
  echo
  echo "Adding private key to SSH Agent"
  ssh-add "$HOME/.ssh/id_ed25519"
fi

echo "Copying SSH public key in the clipboard"
pbcopy < "$HOME/.ssh/id_ed25519.pub"

echo
echo "Now navigate to https://github.com/settings/keys"
echo "and press on New SSH Key"
echo
echo "1. Assign a custom title. For example: macOS SSH Key"
echo "2. and then press COMMAND + V in the Key field"
echo "3. Hit Add SSH Key"
echo "4. Confirm with your password and then enable SSO if needed with your organization"