#!/usr/bin/env bash
# install-agent.sh -- Install and configure the MCP agent.
#
# Usage: install-agent.sh [path-to-mcp-agent-binary]
#
# This script is idempotent and safe to run multiple times.

set -euo pipefail

if [[ "$(id -u)" -ne 0 ]]; then
    echo "error: this script must be run as root" >&2
    exit 1
fi

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
DEPLOY_DIR="$(cd "${SCRIPT_DIR}/.." && pwd)"
BINARY="${1:-./mcp-agent}"

# ------------------------------------------------------------------
# 1. Create mcp user and group
# ------------------------------------------------------------------
if ! id -u mcp &>/dev/null; then
    useradd --system --shell /sbin/nologin --home-dir /srv/mcp --no-create-home mcp
    echo "Created system user: mcp"
else
    echo "User mcp already exists"
fi

# ------------------------------------------------------------------
# 2. Create directories
# ------------------------------------------------------------------
install -d -o mcp -g mcp -m 0750 /srv/mcp
install -d -o mcp -g mcp -m 0750 /srv/mcp/certs
install -d -o mcp -g mcp -m 0750 /srv/mcp/backups

# ------------------------------------------------------------------
# 3. Install binary
# ------------------------------------------------------------------
if [[ ! -f "${BINARY}" ]]; then
    echo "error: binary not found: ${BINARY}" >&2
    echo "Usage: $0 [path-to-mcp-agent-binary]" >&2
    exit 1
fi

install -o root -g root -m 0755 "${BINARY}" /usr/local/bin/mcp-agent
echo "Installed mcp-agent to /usr/local/bin/mcp-agent"

# ------------------------------------------------------------------
# 4. Install example config if none exists
# ------------------------------------------------------------------
if [[ ! -f /srv/mcp/mcp-agent.toml ]]; then
    install -o mcp -g mcp -m 0640 "${DEPLOY_DIR}/examples/mcp-agent.toml" /srv/mcp/mcp-agent.toml
    echo "Installed example config to /srv/mcp/mcp-agent.toml (edit before starting)"
else
    echo "Config /srv/mcp/mcp-agent.toml already exists, skipping"
fi

# ------------------------------------------------------------------
# 5. Install systemd units
# ------------------------------------------------------------------
install -o root -g root -m 0644 "${DEPLOY_DIR}/systemd/mcp-agent.service" /etc/systemd/system/
install -o root -g root -m 0644 "${DEPLOY_DIR}/systemd/mcp-agent-backup.service" /etc/systemd/system/
install -o root -g root -m 0644 "${DEPLOY_DIR}/systemd/mcp-agent-backup.timer" /etc/systemd/system/

# ------------------------------------------------------------------
# 6. Reload systemd
# ------------------------------------------------------------------
systemctl daemon-reload
echo "Systemd units installed and daemon reloaded"

# ------------------------------------------------------------------
# 7. Next steps
# ------------------------------------------------------------------
cat <<'NEXT'

--- Next steps ---
1. Edit /srv/mcp/mcp-agent.toml:
   - Set server.grpc_addr to this node's overlay IP
   - Set agent.node_name to this node's name
   - Set mcias.server_url to the MCIAS server address
   - Place TLS cert/key in /srv/mcp/certs/

2. Enable and start the agent:
   systemctl enable --now mcp-agent

3. Enable the daily backup timer:
   systemctl enable --now mcp-agent-backup.timer

4. Verify the agent is running:
   systemctl status mcp-agent
   journalctl -u mcp-agent -f
NEXT