#!/usr/bin/env bash
#
# setup-student.sh
#
# Usage:
#   curl -sL URL_TO_THIS_SCRIPT | bash -s -- GITHUB_USERNAME
#
# This script must be run as the 'rocky' user (with passwordless sudo).
# It takes one argument: the GitHub username of the student.
# It will:
#   1. Retrieve the student's public SSH keys from GitHub and install them
#      so they can SSH in as 'rocky'.
#   2. Install cowsay, screen, and tmux.
#   3. Update /etc/motd to welcome the student via cowsay and point them
#      at the tutorial repo.

set -euo pipefail

if [ "$#" -ne 1 ]; then
  echo "Error: Missing GitHub username."
  echo "Usage: $0 GITHUB_USERNAME"
  exit 1
fi

GH_USER="$1"
SSH_DIR="/home/rocky/.ssh"
AUTHORIZED_KEYS="$SSH_DIR/authorized_keys"
MOTD_FILE="/etc/motd"
TUTORIAL_URL="https://github.com/OpenCHAMI/tutorial-2025"

echo "→ Installing SSH keys for GitHub user '$GH_USER'..."

# Create .ssh directory if needed
sudo mkdir -p "$SSH_DIR"
sudo chmod 700 "$SSH_DIR"

# Fetch and install public keys
KEYS=$(curl -fsSL "https://github.com/${GH_USER}.keys")
if [ ! -z "${KEYS}" ]; then
  echo "${KEYS}" | sudo tee "$AUTHORIZED_KEYS" >/dev/null
  echo "   ✓ Retrieved keys from https://github.com/${GH_USER}.keys"
else
  echo "   ✗ Could not find keys for user '$GH_USER'; please check the username and that authorization SSH keys are present."
  exit 2
fi

sudo chmod 600 "$AUTHORIZED_KEYS"
sudo chown -R rocky:rocky "$SSH_DIR"

echo "→ Installing packages: cowsay, screen, tmux..."
sudo dnf install -y cowsay screen tmux

echo "→ Updating MOTD in $MOTD_FILE..."

# Generate motd with cowsay greeting and tutorial link
sudo tee "$MOTD_FILE" >/dev/null <<EOF
$(/usr/bin/cowsay "Welcome, ${GH_USER}!")
To get started, see the tutorial at:
${TUTORIAL_URL}
EOF

echo "✔ Setup complete. Student '$GH_USER' can now SSH in and will be greeted on login."