#!/usr/bin/env bash
set -euo pipefail

# ---------------------------------------------------------------------------
# Klauke Enterprises — Observability Agent Installer
#
# Usage:
#   curl -sL https://installer.observability.klauke-enterprises.io | bash -s -- --api-key <KEY>
#
# Installs node_exporter, vmagent, vlagent and configures systemd-journal-upload
# to ship metrics and logs to the central observability platform.
# ---------------------------------------------------------------------------

# --- Versions (pinned) -----------------------------------------------------
NODE_EXPORTER_VERSION="1.9.1"
VMAGENT_VERSION="1.118.0"
VLAGENT_VERSION="1.46.0"

# --- Endpoints --------------------------------------------------------------
METRICS_ENDPOINT="https://ingest.observability.klauke-enterprises.io"
LOGS_ENDPOINT="https://logs.observability.klauke-enterprises.io"

# --- Defaults ---------------------------------------------------------------
SCRAPE_INTERVAL="30s"
API_KEY=""

# ---------------------------------------------------------------------------
# Helpers
# ---------------------------------------------------------------------------
info()  { printf '\033[1;34m[INFO]\033[0m  %s\n' "$*"; }
warn()  { printf '\033[1;33m[WARN]\033[0m  %s\n' "$*"; }
error() { printf '\033[1;31m[ERROR]\033[0m %s\n' "$*" >&2; }
fatal() { error "$@"; exit 1; }

# ---------------------------------------------------------------------------
# Pre-flight checks
# ---------------------------------------------------------------------------
if [ "$(id -u)" -ne 0 ]; then
  fatal "Dieses Script muss als root ausgefuehrt werden."
fi

if ! grep -qiE 'debian|ubuntu' /etc/os-release 2>/dev/null; then
  fatal "Nur Debian und Ubuntu werden unterstuetzt."
fi

# ---------------------------------------------------------------------------
# Argument parsing
# ---------------------------------------------------------------------------
while [ $# -gt 0 ]; do
  case "$1" in
    --api-key)
      shift
      API_KEY="${1:-}"
      ;;
    --api-key=*)
      API_KEY="${1#*=}"
      ;;
    *)
      warn "Unbekanntes Argument: $1"
      ;;
  esac
  shift
done

if [ -z "$API_KEY" ]; then
  fatal "Bitte --api-key angeben. Beispiel: bash install.sh --api-key MEIN_KEY"
fi

HOSTNAME_FQDN="$(hostname -f 2>/dev/null || hostname)"

# ---------------------------------------------------------------------------
# 1. node_exporter
# ---------------------------------------------------------------------------
install_node_exporter() {
  info "Installiere node_exporter v${NODE_EXPORTER_VERSION} ..."

  local url="https://github.com/prometheus/node_exporter/releases/download/v${NODE_EXPORTER_VERSION}/node_exporter-${NODE_EXPORTER_VERSION}.linux-amd64.tar.gz"
  local tmp="/tmp/node_exporter-${NODE_EXPORTER_VERSION}.tar.gz"
  local dir="/tmp/node_exporter-${NODE_EXPORTER_VERSION}.linux-amd64"

  # System user
  id -u node_exporter &>/dev/null || useradd --system --no-create-home --shell /usr/sbin/nologin node_exporter

  # Download & extract
  curl -fsSL -o "$tmp" "$url"
  tar -xzf "$tmp" -C /tmp
  install -o root -g root -m 0755 "${dir}/node_exporter" /usr/local/bin/node_exporter

  # Systemd unit
  cat > /etc/systemd/system/node_exporter.service <<'UNIT'
[Unit]
Description=Prometheus Node Exporter
After=network-online.target
Wants=network-online.target

[Service]
User=node_exporter
Group=node_exporter
Type=simple
ExecStart=/usr/local/bin/node_exporter \
  --web.listen-address=:9100
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target
UNIT

  systemctl daemon-reload
  systemctl enable --now node_exporter

  # Cleanup
  rm -rf "$tmp" "$dir"
  info "node_exporter laeuft."
}

# ---------------------------------------------------------------------------
# 2. vmagent
# ---------------------------------------------------------------------------
install_vmagent() {
  info "Installiere vmagent v${VMAGENT_VERSION} ..."

  local url="https://github.com/VictoriaMetrics/VictoriaMetrics/releases/download/v${VMAGENT_VERSION}/vmutils-linux-amd64-v${VMAGENT_VERSION}.tar.gz"
  local tmp="/tmp/vmutils-${VMAGENT_VERSION}.tar.gz"

  # System user
  id -u vmagent &>/dev/null || useradd --system --no-create-home --shell /usr/sbin/nologin vmagent

  # Directories
  install -d -o vmagent -g vmagent -m 0755 /etc/vmagent
  install -d -o vmagent -g vmagent -m 0755 /var/lib/vmagent

  # Download & extract
  curl -fsSL -o "$tmp" "$url"
  tar -xzf "$tmp" -C /tmp
  install -o root -g root -m 0755 /tmp/vmagent-prod /usr/local/bin/vmagent

  # Scrape config
  cat > /etc/vmagent/config.yml <<EOF
global:
  scrape_interval: ${SCRAPE_INTERVAL}

scrape_configs:
  - job_name: node_exporter
    static_configs:
      - targets: ["localhost:9100"]
    relabel_configs:
      - source_labels: [__address__]
        target_label: instance
        replacement: "${HOSTNAME_FQDN}"
EOF
  chown vmagent:vmagent /etc/vmagent/config.yml
  chmod 0640 /etc/vmagent/config.yml

  # Systemd unit
  cat > /etc/systemd/system/vmagent.service <<UNIT
[Unit]
Description=VictoriaMetrics vmagent
After=network-online.target
Wants=network-online.target

[Service]
User=vmagent
Group=vmagent
Type=simple
ExecStart=/usr/local/bin/vmagent \\
  -promscrape.config=/etc/vmagent/config.yml \\
  -remoteWrite.url=${METRICS_ENDPOINT}/api/v1/write \\
  -remoteWrite.bearerToken=${API_KEY} \\
  -remoteWrite.tmpDataPath=/var/lib/vmagent
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target
UNIT

  systemctl daemon-reload
  systemctl enable --now vmagent

  # Cleanup
  rm -rf "$tmp" /tmp/vmagent-prod /tmp/vmalert-prod /tmp/vmauth-prod /tmp/vmbackup-prod /tmp/vmrestore-prod /tmp/vmctl-prod
  info "vmagent laeuft."
}

# ---------------------------------------------------------------------------
# 3. vlagent
# ---------------------------------------------------------------------------
install_vlagent() {
  info "Installiere vlagent v${VLAGENT_VERSION} ..."

  local url="https://github.com/VictoriaMetrics/VictoriaLogs/releases/download/v${VLAGENT_VERSION}/vlutils-linux-amd64-v${VLAGENT_VERSION}.tar.gz"
  local tmp="/tmp/vlutils-${VLAGENT_VERSION}.tar.gz"

  # System user
  id -u vlagent &>/dev/null || useradd --system --no-create-home --shell /usr/sbin/nologin vlagent

  # Directories
  install -d -o vlagent -g vlagent -m 0755 /etc/vlagent
  install -d -o vlagent -g vlagent -m 0755 /var/lib/vlagent

  # Download & extract
  curl -fsSL -o "$tmp" "$url"
  tar -xzf "$tmp" -C /tmp
  install -o root -g root -m 0755 /tmp/vlagent-prod /usr/local/bin/vlagent

  # Bearer token file
  printf '%s' "$API_KEY" > /etc/vlagent/bearer-token
  chown vlagent:vlagent /etc/vlagent/bearer-token
  chmod 0600 /etc/vlagent/bearer-token

  # Systemd unit
  cat > /etc/systemd/system/vlagent.service <<UNIT
[Unit]
Description=VictoriaLogs vlagent
After=network-online.target
Wants=network-online.target

[Service]
User=vlagent
Group=vlagent
Type=simple
ExecStart=/usr/local/bin/vlagent \\
  -remoteWrite.url=${LOGS_ENDPOINT}/insert/native \\
  -remoteWrite.bearerTokenFile=/etc/vlagent/bearer-token \\
  -remoteWrite.tmpDataPath=/var/lib/vlagent
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target
UNIT

  systemctl daemon-reload
  systemctl enable --now vlagent

  # Cleanup
  rm -rf "$tmp" /tmp/vlagent-prod /tmp/vlctl-prod
  info "vlagent laeuft."
}

# ---------------------------------------------------------------------------
# 4. systemd-journal-upload
# ---------------------------------------------------------------------------
configure_journal_upload() {
  info "Konfiguriere systemd-journal-upload ..."

  apt-get update -qq
  apt-get install -y -qq systemd-journal-remote

  install -d -m 0755 /etc/systemd/journal-upload.conf.d

  cat > /etc/systemd/journal-upload.conf.d/vlagent.conf <<'CONF'
[Upload]
URL=http://localhost:9429/insert/journald
CONF

  systemctl daemon-reload
  systemctl enable --now systemd-journal-upload
  info "systemd-journal-upload laeuft."
}

# ---------------------------------------------------------------------------
# Main
# ---------------------------------------------------------------------------
info "Klauke Enterprises Observability Agent Installer"
info "API-Key: ${API_KEY:0:8}..."
info "Hostname: ${HOSTNAME_FQDN}"
info ""

install_node_exporter
install_vmagent
install_vlagent
configure_journal_upload

info ""
info "Installation abgeschlossen."
info "  Metrics  -> ${METRICS_ENDPOINT}"
info "  Logs     -> ${LOGS_ENDPOINT}"