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

VMID=9000
NAME=debian-13-genericcloud
IMAGE_URL=https://cloud.debian.org/images/cloud/trixie/latest/debian-13-genericcloud-amd64.qcow2
IMAGE_FILE=
CACHE_DIR=/var/lib/vz/template/qcow2
STORAGE=local-lvm
CLOUDINIT_STORAGE=
BRIDGE=vmbr0
MEMORY=2048
CORES=2
CPU=host
DISK_SIZE=32G
MACHINE=q35
BIOS=ovmf
SCSI_HW=virtio-scsi-pci
NET_MODEL=virtio
PBS_STORAGE=
DRY_RUN=0
ASSUME_YES=0
INTERACTIVE=1
VMID_SET=0
NAME_SET=0
IMAGE_URL_SET=0
IMAGE_FILE_SET=0
CACHE_DIR_SET=0
STORAGE_SET=0
CLOUDINIT_STORAGE_SET=0
BRIDGE_SET=0
MEMORY_SET=0
CORES_SET=0
CPU_SET=0
DISK_SIZE_SET=0
PBS_STORAGE_SET=0

usage() {
  cat <<'USAGE'
Create a Proxmox VM template from the Debian 13 GenericCloud image.

Run this on a Proxmox node as root.

Usage:
  scripts/create-proxmox-template.sh [options]

Options:
  --vmid ID                 Template VMID. Default: 9000
  --name NAME               Template name. Default: debian-13-genericcloud
  --storage STORAGE         Disk storage. Default: local-lvm
  --cloudinit-storage NAME  Cloud-Init storage. Default: same as --storage
  --bridge BRIDGE           Network bridge. Default: vmbr0
  --memory MB               Memory in MB. Default: 2048
  --cores N                 vCPU count. Default: 2
  --cpu TYPE                CPU type. Default: host
  --disk-size SIZE          Resize imported disk to this size. Default: 32G
  --image-url URL           Debian GenericCloud qcow2 URL.
  --image-file PATH         Use an existing local qcow2 instead of downloading.
  --cache-dir PATH          Download cache directory. Default: /var/lib/vz/template/qcow2
  --pbs-storage NAME        PBS storage/datastore ID. Enables main disk backup flag when set.
  --dry-run                 Print commands without executing them.
  --yes                     Accept defaults for any unanswered prompts.
  --non-interactive         Do not prompt; use defaults and provided flags.
  -h, --help                Show this help.

The template is configured with:
  - Q35 machine type
  - OVMF / UEFI
  - VirtIO SCSI
  - VirtIO network
  - QEMU guest agent
  - Cloud-Init drive
  - serial0 socket
  - vga serial0 for Proxmox xterm.js console support
USAGE
}

prompt_value() {
  local label=$1
  local default_value=$2
  local value

  if [ "$ASSUME_YES" -eq 1 ] || [ "$INTERACTIVE" -eq 0 ] || [ ! -t 0 ]; then
    printf '%s\n' "$default_value"
    return 0
  fi

  printf '%s [%s]: ' "$label" "$default_value" >&2
  read -r value
  if [ -z "$value" ]; then
    printf '%s\n' "$default_value"
  else
    printf '%s\n' "$value"
  fi
}

prompt_optional_value() {
  local label=$1
  local value

  if [ "$ASSUME_YES" -eq 1 ] || [ "$INTERACTIVE" -eq 0 ] || [ ! -t 0 ]; then
    printf '\n'
    return 0
  fi

  printf '%s [leave empty]: ' "$label" >&2
  read -r value
  printf '%s\n' "$value"
}

prompt_confirm() {
  local label=$1
  local value

  if [ "$ASSUME_YES" -eq 1 ] || [ "$INTERACTIVE" -eq 0 ] || [ ! -t 0 ]; then
    return 0
  fi

  printf '%s [Y/n]: ' "$label" >&2
  read -r value
  case "$value" in
    ""|y|Y|yes|YES)
      return 0
      ;;
    *)
      return 1
      ;;
  esac
}

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

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

run() {
  if [ "$DRY_RUN" -eq 1 ]; then
    printf '+'
    printf ' %q' "$@"
    printf '\n'
    return 0
  fi
  "$@"
}

need_command() {
  command -v "$1" >/dev/null 2>&1 || die "required command not found: $1"
}

download_image() {
  local url=$1
  local dest=$2

  if [ -s "$dest" ]; then
    log "Using cached image: $dest"
    return 0
  fi

  run mkdir -p "$(dirname "$dest")"
  if command -v curl >/dev/null 2>&1; then
    run curl -fL --retry 3 --retry-delay 2 -o "$dest" "$url"
  elif command -v wget >/dev/null 2>&1; then
    run wget -O "$dest" "$url"
  else
    die "curl or wget is required to download the image"
  fi
}

parse_args() {
  while [ "$#" -gt 0 ]; do
    case "$1" in
      --vmid)
        VMID=${2:?missing value for --vmid}
        VMID_SET=1
        shift 2
        ;;
      --name)
        NAME=${2:?missing value for --name}
        NAME_SET=1
        shift 2
        ;;
      --storage)
        STORAGE=${2:?missing value for --storage}
        STORAGE_SET=1
        shift 2
        ;;
      --cloudinit-storage)
        CLOUDINIT_STORAGE=${2:?missing value for --cloudinit-storage}
        CLOUDINIT_STORAGE_SET=1
        shift 2
        ;;
      --bridge)
        BRIDGE=${2:?missing value for --bridge}
        BRIDGE_SET=1
        shift 2
        ;;
      --memory)
        MEMORY=${2:?missing value for --memory}
        MEMORY_SET=1
        shift 2
        ;;
      --cores)
        CORES=${2:?missing value for --cores}
        CORES_SET=1
        shift 2
        ;;
      --cpu)
        CPU=${2:?missing value for --cpu}
        CPU_SET=1
        shift 2
        ;;
      --disk-size)
        DISK_SIZE=${2:?missing value for --disk-size}
        DISK_SIZE_SET=1
        shift 2
        ;;
      --image-url)
        IMAGE_URL=${2:?missing value for --image-url}
        IMAGE_URL_SET=1
        shift 2
        ;;
      --image-file)
        IMAGE_FILE=${2:?missing value for --image-file}
        IMAGE_FILE_SET=1
        shift 2
        ;;
      --cache-dir)
        CACHE_DIR=${2:?missing value for --cache-dir}
        CACHE_DIR_SET=1
        shift 2
        ;;
      --pbs-storage)
        PBS_STORAGE=${2:?missing value for --pbs-storage}
        PBS_STORAGE_SET=1
        shift 2
        ;;
      --dry-run)
        DRY_RUN=1
        shift
        ;;
      --yes)
        ASSUME_YES=1
        shift
        ;;
      --non-interactive)
        INTERACTIVE=0
        shift
        ;;
      -h|--help)
        usage
        exit 0
        ;;
      *)
        die "unknown option: $1"
        ;;
    esac
  done
}

collect_interactive_config() {
  if [ "$VMID_SET" -eq 0 ]; then
    VMID=$(prompt_value "Template VMID" "$VMID")
  fi
  if [ "$NAME_SET" -eq 0 ]; then
    NAME=$(prompt_value "Template name" "$NAME")
  fi
  if [ "$STORAGE_SET" -eq 0 ]; then
    STORAGE=$(prompt_value "Disk storage" "$STORAGE")
  fi
  if [ "$CLOUDINIT_STORAGE_SET" -eq 0 ]; then
    CLOUDINIT_STORAGE=$(prompt_value "Cloud-Init storage" "${CLOUDINIT_STORAGE:-$STORAGE}")
  fi
  if [ "$BRIDGE_SET" -eq 0 ]; then
    BRIDGE=$(prompt_value "Network bridge" "$BRIDGE")
  fi
  if [ "$MEMORY_SET" -eq 0 ]; then
    MEMORY=$(prompt_value "Memory MB" "$MEMORY")
  fi
  if [ "$CORES_SET" -eq 0 ]; then
    CORES=$(prompt_value "vCPU cores" "$CORES")
  fi
  if [ "$CPU_SET" -eq 0 ]; then
    CPU=$(prompt_value "CPU type" "$CPU")
  fi
  if [ "$DISK_SIZE_SET" -eq 0 ]; then
    DISK_SIZE=$(prompt_value "Disk size after resize" "$DISK_SIZE")
  fi
  if [ "$CACHE_DIR_SET" -eq 0 ]; then
    CACHE_DIR=$(prompt_value "Image cache directory" "$CACHE_DIR")
  fi
  if [ "$IMAGE_FILE_SET" -eq 0 ]; then
    IMAGE_FILE=$(prompt_optional_value "Local qcow2 image file")
  fi
  if [ -z "$IMAGE_FILE" ] && [ "$IMAGE_URL_SET" -eq 0 ]; then
    IMAGE_URL=$(prompt_value "Debian GenericCloud image URL" "$IMAGE_URL")
  fi
  if [ "$PBS_STORAGE_SET" -eq 0 ]; then
    PBS_STORAGE=$(prompt_optional_value "PBS storage/datastore ID for backup flag")
  fi
}

print_summary() {
  cat <<SUMMARY

Template configuration:
  VMID:               $VMID
  Name:               $NAME
  Disk storage:       $STORAGE
  Cloud-Init storage: $CLOUDINIT_STORAGE
  Bridge:             $BRIDGE
  Memory:             $MEMORY MB
  Cores:              $CORES
  CPU:                $CPU
  Disk size:          $DISK_SIZE
  Machine:            $MACHINE
  BIOS:               $BIOS
  Serial console:     serial0 socket, vga serial0
SUMMARY

  if [ -n "$IMAGE_FILE" ]; then
    printf '  Image file:         %s\n' "$IMAGE_FILE"
  else
    printf '  Image URL:          %s\n' "$IMAGE_URL"
    printf '  Cache directory:    %s\n' "$CACHE_DIR"
  fi
  if [ "$DRY_RUN" -eq 1 ]; then
    printf '  Mode:               dry-run\n'
  fi
  if [ -n "$PBS_STORAGE" ]; then
    printf '  Backup flag:        enabled for main disk; PBS storage: %s\n' "$PBS_STORAGE"
  else
    printf '  Backup flag:        disabled for main disk\n'
  fi
  printf '\n'
}

main() {
  parse_args "$@"

  collect_interactive_config

  if [ -z "$CLOUDINIT_STORAGE" ]; then
    CLOUDINIT_STORAGE=$STORAGE
  fi

  print_summary
  if ! prompt_confirm "Create this Proxmox template?"; then
    die "cancelled"
  fi

  if [ "$DRY_RUN" -eq 0 ]; then
    need_command qm
    need_command awk
  fi

  if [ "$(id -u)" -ne 0 ] && [ "$DRY_RUN" -eq 0 ]; then
    die "run this script as root on a Proxmox node"
  fi

  if [ "$DRY_RUN" -eq 0 ] && qm status "$VMID" >/dev/null 2>&1; then
    die "VMID $VMID already exists; choose another --vmid or remove it manually"
  fi

  local image_path
  if [ -n "$IMAGE_FILE" ]; then
    image_path=$IMAGE_FILE
    [ "$DRY_RUN" -eq 1 ] || [ -f "$image_path" ] || die "image file not found: $image_path"
  else
    image_path="$CACHE_DIR/$(basename "$IMAGE_URL")"
    download_image "$IMAGE_URL" "$image_path"
  fi

  run qm create "$VMID" \
    --name "$NAME" \
    --ostype l26 \
    --machine "$MACHINE" \
    --bios "$BIOS" \
    --memory "$MEMORY" \
    --cores "$CORES" \
    --cpu "$CPU" \
    --agent enabled=1 \
    --scsihw "$SCSI_HW" \
    --net0 "$NET_MODEL,bridge=$BRIDGE" \
    --serial0 socket \
    --vga serial0

  if [ "$BIOS" = "ovmf" ]; then
    run qm set "$VMID" --efidisk0 "$STORAGE:0,pre-enrolled-keys=0"
  fi

  run qm importdisk "$VMID" "$image_path" "$STORAGE"

  local imported_disk
  if [ "$DRY_RUN" -eq 1 ]; then
    imported_disk="$STORAGE:vm-$VMID-disk-0"
    log "Dry-run assumption: imported disk will be $imported_disk"
  else
    imported_disk=$(qm config "$VMID" | awk -F': ' '/^unused[0-9]+:/{print $2; exit}')
    [ -n "$imported_disk" ] || die "could not find imported unused disk in qm config for VMID $VMID"
  fi

  local disk_backup=0
  if [ -n "$PBS_STORAGE" ]; then
    disk_backup=1
  fi

  run qm set "$VMID" --scsi0 "$imported_disk,discard=on,ssd=1,backup=$disk_backup"
  run qm set "$VMID" --ide2 "$CLOUDINIT_STORAGE:cloudinit"
  run qm set "$VMID" --boot order=scsi0
  run qm set "$VMID" --ipconfig0 ip=dhcp

  if [ -n "$DISK_SIZE" ]; then
    run qm resize "$VMID" scsi0 "$DISK_SIZE"
  fi

  run qm template "$VMID"

  log "Created Proxmox template $NAME ($VMID)"
}

main "$@"