#!/bin/sh
set -eu

repo="juspay/nixden"
name="${NIXDEN_NAME:-nixden}"
tag="${NIXDEN_TAG:-latest}"
template_url="${NIXDEN_TEMPLATE_URL:-}"
transfer_dir="${NIXDEN_TRANSFER_DIR:-/tmp/lima-nixden}"
cpus="${NIXDEN_CPUS:-}"
memory="${NIXDEN_MEMORY:-}"
disk="${NIXDEN_DISK:-}"
auto_size=1
cpus_explicit=0
memory_explicit=0
disk_explicit=0

[ -n "${NIXDEN_CPUS:-}" ] && cpus_explicit=1
[ -n "${NIXDEN_MEMORY:-}" ] && memory_explicit=1
[ -n "${NIXDEN_DISK:-}" ] && disk_explicit=1

if [ "${NIXDEN_LIMA_DEFAULTS:-}" = "1" ]; then
  auto_size=0
fi

if [ "${NIXDEN_COLOR:-}" = "1" ]; then
  use_color=1
elif [ "${NIXDEN_COLOR:-}" = "0" ] || [ "${NO_COLOR:-}" ]; then
  use_color=0
elif [ -t 1 ]; then
  use_color=1
else
  use_color=0
fi

if [ "$use_color" = "1" ]; then
  bold="$(printf '\033[1m')"
  dim="$(printf '\033[2m')"
  blue="$(printf '\033[34m')"
  green="$(printf '\033[32m')"
  yellow="$(printf '\033[33m')"
  red="$(printf '\033[31m')"
  reset="$(printf '\033[0m')"
else
  bold=""
  dim=""
  blue=""
  green=""
  yellow=""
  red=""
  reset=""
fi

phase_no=0

say() {
  printf '%s\n' "$*"
}

phase() {
  phase_no=$((phase_no + 1))
  printf '\n%s[%s]%s %s%s%s\n' "$blue" "$phase_no" "$reset" "$bold" "$*" "$reset"
}

info() {
  printf '  %s-%s %s\n' "$dim" "$reset" "$*"
}

ok() {
  printf '  %sOK%s %s\n' "$green" "$reset" "$*"
}

warn() {
  printf '  %s!%s %s\n' "$yellow" "$reset" "$*"
}

die() {
  printf '%sError:%s %s\n' "$red" "$reset" "$*" >&2
  exit 1
}

usage() {
  cat <<'EOF'
nixden starter

Usage:
  curl -fsSL https://juspay.github.io/nixden/start | sh -
  curl -fsSL https://juspay.github.io/nixden/start | sh -s -- [options]

Options:
  --name NAME          Lima instance name (default: nixden)
  --tag TAG            nixden release tag, or latest (default: latest)
  --template-url URL   Full Lima template URL to use instead of --tag
  --cpus N             Override CPU count
  --memory GIB         Override memory in GiB
  --disk GIB           Override disk size in GiB
  --lima-defaults      Do not auto-size CPU, memory, or disk
  -h, --help           Show this help

Environment overrides:
  NIXDEN_NAME, NIXDEN_TAG, NIXDEN_TEMPLATE_URL, NIXDEN_CPUS,
  NIXDEN_MEMORY, NIXDEN_DISK, NIXDEN_TRANSFER_DIR,
  NIXDEN_LIMA_DEFAULTS=1, NIXDEN_COLOR=0|1, NO_COLOR=1
EOF
}

need_value() {
  [ $# -ge 2 ] || die "missing value for $1"
}

while [ $# -gt 0 ]; do
  case "$1" in
    --name)
      need_value "$@"
      shift
      name="$1"
      ;;
    --name=*)
      name="${1#--name=}"
      ;;
    --tag)
      need_value "$@"
      shift
      tag="$1"
      ;;
    --tag=*)
      tag="${1#--tag=}"
      ;;
    --template-url)
      need_value "$@"
      shift
      template_url="$1"
      ;;
    --template-url=*)
      template_url="${1#--template-url=}"
      ;;
    --cpus)
      need_value "$@"
      shift
      cpus="$1"
      cpus_explicit=1
      ;;
    --cpus=*)
      cpus="${1#--cpus=}"
      cpus_explicit=1
      ;;
    --memory)
      need_value "$@"
      shift
      memory="$1"
      memory_explicit=1
      ;;
    --memory=*)
      memory="${1#--memory=}"
      memory_explicit=1
      ;;
    --disk)
      need_value "$@"
      shift
      disk="$1"
      disk_explicit=1
      ;;
    --disk=*)
      disk="${1#--disk=}"
      disk_explicit=1
      ;;
    --lima-defaults)
      auto_size=0
      ;;
    -h|--help)
      usage
      exit 0
      ;;
    *)
      die "unknown argument: $1"
      ;;
  esac
  shift
done

floor_at() {
  value="$1"
  minimum="$2"
  if [ "$value" -lt "$minimum" ]; then
    printf '%s\n' "$minimum"
  else
    printf '%s\n' "$value"
  fi
}

detect_cpus() {
  if command -v sysctl >/dev/null 2>&1; then
    n="$(sysctl -n hw.ncpu 2>/dev/null || true)"
  else
    n=""
  fi
  if [ -z "$n" ] && command -v getconf >/dev/null 2>&1; then
    n="$(getconf _NPROCESSORS_ONLN 2>/dev/null || true)"
  fi
  case "$n" in
    ''|*[!0-9]*) return 0 ;;
  esac
  floor_at "$((n - 2))" 1
}

detect_memory() {
  bytes=""
  if command -v sysctl >/dev/null 2>&1; then
    bytes="$(sysctl -n hw.memsize 2>/dev/null || true)"
  fi
  if [ -n "$bytes" ]; then
    gib="$((bytes / 1073741824 - 4))"
    floor_at "$gib" 2
    return 0
  fi
  if [ -r /proc/meminfo ]; then
    kib="$(awk '/MemTotal:/ { print $2 }' /proc/meminfo)"
    case "$kib" in
      ''|*[!0-9]*) return 0 ;;
    esac
    gib="$((kib / 1024 / 1024 - 4))"
    floor_at "$gib" 2
  fi
}

detect_disk() {
  free_kib="$(df -k / 2>/dev/null | awk 'NR==2 { print $4 }')"
  case "$free_kib" in
    ''|*[!0-9]*) return 0 ;;
  esac
  gib="$((free_kib / 1024 / 1024 / 2))"
  floor_at "$gib" 32
}

gib_to_bytes() {
  value="$1"
  case "$value" in
    ''|*[!0-9]*) return 1 ;;
  esac
  printf '%s\n' "$((value * 1073741824))"
}

instance_exists() {
  limactl list -q 2>/dev/null | grep -Fxq "$name"
}

instance_status() {
  limactl list --format '{{.Status}}' "$name" 2>/dev/null || printf 'Unknown'
}

resource_mismatches() {
  actual="$(limactl list --format '{{.CPUs}} {{.Memory}} {{.Disk}}' "$name" 2>/dev/null || true)"
  [ -n "$actual" ] || return 0

  set -- $actual
  actual_cpus="${1:-}"
  actual_memory="${2:-}"
  actual_disk="${3:-}"

  mismatch=0
  if [ -n "$cpus" ] && [ -n "$actual_cpus" ] && [ "$actual_cpus" != "$cpus" ]; then
    warn "Existing VM CPUs: $actual_cpus; requested: $cpus"
    mismatch=1
  fi

  desired_memory="$(gib_to_bytes "$memory" 2>/dev/null || true)"
  if [ -n "$desired_memory" ] && [ -n "$actual_memory" ] && [ "$actual_memory" != "$desired_memory" ]; then
    warn "Existing VM memory: $((actual_memory / 1073741824)) GiB; requested: ${memory} GiB"
    mismatch=1
  fi

  desired_disk="$(gib_to_bytes "$disk" 2>/dev/null || true)"
  if [ "$disk_explicit" = "1" ] && [ -n "$desired_disk" ] && [ -n "$actual_disk" ] && [ "$actual_disk" != "$desired_disk" ]; then
    warn "Existing VM disk: $((actual_disk / 1073741824)) GiB; requested: ${disk} GiB"
    mismatch=1
  fi

  if [ "$mismatch" = "1" ]; then
    warn "Existing Lima VMs keep their original resources."
    warn "To recreate with requested resources:"
    warn "  limactl delete $name"
    warn "  curl -fsSL https://juspay.github.io/nixden/start | sh -"
  fi
}

box_line() {
  printf '%s\n' "  | $*"
}

say "${bold}nixden${reset}"

phase "Checking requirements"
if ! command -v limactl >/dev/null 2>&1; then
  case "$(uname -s 2>/dev/null || true)" in
    Darwin)
      install_hint="brew install lima"
      ;;
    Linux)
      install_hint="See https://lima-vm.io/docs/installation/ for Linux packages."
      ;;
    *)
      install_hint="See https://lima-vm.io/docs/installation/."
      ;;
  esac
  cat >&2 <<EOF
Error: Lima is not installed.

Install Lima first:
  $install_hint

Other installation options:
  https://lima-vm.io/docs/installation/
EOF
  exit 1
fi
lima_path="$(command -v limactl)"
ok "Lima installed: $(limactl --version 2>/dev/null || printf 'limactl found')"
info "$lima_path"

if [ -z "$template_url" ]; then
  if [ "$tag" = "latest" ]; then
    template_url="https://github.com/$repo/releases/latest/download/nixden-lima.yaml"
  else
    template_url="https://github.com/$repo/releases/download/$tag/nixden-lima.yaml"
  fi
fi
ok "Release template selected"
info "$template_url"

phase "Choosing VM resources"
if [ "$auto_size" = "1" ]; then
  [ -n "$cpus" ] || cpus="$(detect_cpus || true)"
  [ -n "$memory" ] || memory="$(detect_memory || true)"
  [ -n "$disk" ] || disk="$(detect_disk || true)"
  [ -n "$cpus" ] && ok "CPUs: $cpus" || warn "CPU count not detected; Lima default will be used"
  [ -n "$memory" ] && ok "Memory: ${memory} GiB" || warn "Memory not detected; Lima default will be used"
  [ -n "$disk" ] && ok "Disk: ${disk} GiB" || warn "Free disk not detected; Lima default will be used"
else
  ok "Using Lima's default CPU, memory, and disk sizing"
fi

phase "Preparing host"
mkdir -p "$transfer_dir"
ok "Transfer directory ready: $transfer_dir"

phase "Starting nixden"
if instance_exists; then
  status="$(instance_status)"
  ok "Found existing Lima instance \"$name\" ($status)"
  resource_mismatches
  if [ "$status" = "Running" ]; then
    ok "VM already running"
  else
    info "Starting existing VM"
    limactl start "$name"
    ok "VM started"
  fi
else
  info "Instance: $name"
  info "Image: Lima will download it if it is not already cached"

  set -- limactl start "--name=$name"
  [ -n "$cpus" ] && set -- "$@" "--cpus=$cpus"
  [ -n "$memory" ] && set -- "$@" "--memory=$memory"
  [ -n "$disk" ] && set -- "$@" "--disk=$disk"
  set -- "$@" "$template_url"
  "$@"
  ok "VM created and started"
fi

phase "Ready"
ok "nixden is ready"
say
say "${bold}Next steps${reset}"
say "  +------------------------------------------------------------"
box_line "Open a shell:"
box_line "  limactl shell --workdir=. $name"
box_line ""
box_line "Transfer files intentionally through:"
box_line "  $transfer_dir"
box_line ""
box_line "Stop or delete the VM:"
box_line "  limactl stop $name"
box_line "  limactl delete $name"
say "  +------------------------------------------------------------"