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

log() {
  printf '[logs] %s\n' "$*"
}

usage() {
  cat <<'EOF'
Usage: ./logs.sh <id-or-name-prefix> [--follow]

Prints the Firecracker log for a VM. Use --follow to tail -f.
EOF
}

get_prop() {
  local info="$1"
  local key="$2"
  awk -F= -v k="$key" '$1==k {print $2}' "$info"
}

find_vm_info() {
  local query="$1"
  local info match_count=0 match=""

  for info in state/vms/*/info; do
    [[ -f "$info" ]] || continue
    local id name
    id="$(get_prop "$info" "id")"
    name="$(get_prop "$info" "name")"
    if [[ "$id" == "$query"* || "$name" == "$query"* ]]; then
      match="$info"
      match_count=$((match_count + 1))
    fi
  done

  if (( match_count == 0 )); then
    log "no VM found for prefix: $query"
    exit 1
  fi
  if (( match_count > 1 )); then
    log "multiple VMs found for prefix: $query"
    exit 1
  fi

  printf '%s' "$match"
}

QUERY="${1:-}"
FOLLOW=0
while [[ $# -gt 0 ]]; do
  case "$1" in
    --follow|-f)
      FOLLOW=1
      shift
      ;;
    -h|--help)
      usage
      exit 0
      ;;
    *)
      if [[ -z "$QUERY" ]]; then
        QUERY="$1"
        shift
      else
        log "unknown option: $1"
        usage
        exit 1
      fi
      ;;
  esac
done

if [[ -z "$QUERY" ]]; then
  usage
  exit 1
fi

INFO_FILE="$(find_vm_info "$QUERY")"
LOG_FILE="$(get_prop "$INFO_FILE" "log")"

if [[ -z "$LOG_FILE" || ! -f "$LOG_FILE" ]]; then
  log "log file not found: $LOG_FILE"
  exit 1
fi

if (( FOLLOW == 1 )); then
  tail -f "$LOG_FILE"
else
  cat "$LOG_FILE"
fi