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

SCRIPT_VERSION="0.1.0-preflight"
LOG_FILE="/var/log/kitms-install.log"

NEEDS_ROOT=1
MIN_FREE_GB=10
REQUIRED_PORTS=(25 80 443)

log() {
  local level="$1"
  shift
  local msg="$*"
  local ts
  ts="$(date -u +"%Y-%m-%dT%H:%M:%SZ")"
  echo "[$ts] [$level] $msg" | tee -a "$LOG_FILE"
}

usage() {
  cat <<'EOF'
KITMS install.sh (preflight profile)

Usage:
  sudo ./install.sh [--preflight-only]

Current behavior:
  - Runs host preflight checks for KITMS installation.
  - Prints a clear summary and exits with status 0 on success.

Notes:
  - Full automatic stack installation is tracked in M6 (Installer MVP).
  - This script currently validates readiness and does not change system mail services.
EOF
}

check_root() {
  if [[ "$NEEDS_ROOT" -eq 1 && "${EUID:-$(id -u)}" -ne 0 ]]; then
    log "ERROR" "Run this script as root (sudo)."
    exit 100
  fi
}

check_os() {
  if [[ ! -f /etc/os-release ]]; then
    log "ERROR" "/etc/os-release not found."
    exit 101
  fi

  # shellcheck disable=SC1091
  . /etc/os-release
  local os="${ID:-unknown}"
  local ver="${VERSION_ID:-unknown}"

  if [[ "$os" != "ubuntu" ]]; then
    log "ERROR" "Unsupported OS: $os. Expected ubuntu."
    exit 102
  fi

  case "$ver" in
    22.04|24.04)
      log "INFO" "OS check passed: Ubuntu $ver"
      ;;
    *)
      log "WARN" "Ubuntu $ver is not in the primary support set (22.04/24.04)."
      ;;
  esac
}

check_disk_space() {
  local avail_kb
  avail_kb="$(df --output=avail / | tail -n1 | tr -d ' ')"
  local avail_gb=$((avail_kb / 1024 / 1024))
  if (( avail_gb < MIN_FREE_GB )); then
    log "ERROR" "Insufficient disk space on '/': ${avail_gb}GB available, need >= ${MIN_FREE_GB}GB."
    exit 103
  fi
  log "INFO" "Disk check passed: ${avail_gb}GB free on '/'."
}

check_network_tools() {
  local missing=0
  for tool in curl apt-get systemctl ss; do
    if ! command -v "$tool" >/dev/null 2>&1; then
      log "ERROR" "Required tool not found: $tool"
      missing=1
    fi
  done

  if (( missing == 1 )); then
    exit 104
  fi
  log "INFO" "Tool check passed."
}

check_ports() {
  local busy=0
  for port in "${REQUIRED_PORTS[@]}"; do
    if ss -ltn "( sport = :$port )" | grep -q ":$port"; then
      log "WARN" "Port $port is already in use."
      busy=1
    fi
  done

  if (( busy == 1 )); then
    log "WARN" "Some target ports are busy. Manual review is required before full install."
  else
    log "INFO" "Port check passed: target ports are free."
  fi
}

check_outbound() {
  if curl -fsSL --max-time 8 https://license.kitms.ru/api/license/check >/dev/null 2>&1; then
    log "INFO" "Outbound connectivity check passed: license.kitms.ru reachable."
  else
    log "WARN" "Outbound connectivity check could not reach license.kitms.ru/api/license/check."
  fi
}

main() {
  local preflight_only=1

  while [[ $# -gt 0 ]]; do
    case "$1" in
      --preflight-only)
        preflight_only=1
        shift
        ;;
      -h|--help)
        usage
        exit 0
        ;;
      *)
        log "ERROR" "Unknown argument: $1"
        usage
        exit 2
        ;;
    esac
  done

  touch "$LOG_FILE"
  chmod 600 "$LOG_FILE"

  log "INFO" "Starting KITMS install preflight (version=$SCRIPT_VERSION)."
  check_root
  check_os
  check_disk_space
  check_network_tools
  check_ports
  check_outbound

  log "INFO" "Preflight checks completed successfully."
  if (( preflight_only == 1 )); then
    log "INFO" "Current profile: preflight-only. Full automatic installation is tracked in M6."
  fi

  log "INFO" "Next step: obtain signed license.json after installation and run activation in KITMS UI."
}

main "$@"