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

SDX="${1:-sdb}"

BOOT="${SDX}1"
ROOT="${SDX}2"

if [[ "$(id -u)" -ne 0 ]]; then
  echo "Run as root."
  echo "sdx as parameter"
  exit 1
fi

echo "Target: /dev/${SDX}"
read -rp "Proceed? (y/N) " yn
[[ "${yn,,}" == "y" ]] || exit 0

# wipe partitions
fdisk /dev/"${SDX}" <<EOF
o
n
p
1

+1G
t
c
n
p
2


w
EOF

# format
mkfs.vfat /dev/"${BOOT}"
mkfs.ext4 /dev/"${ROOT}"

# mount
mkdir -p /mnt/boot /mnt/root
mount /dev/"${BOOT}" /mnt/boot
mount /dev/"${ROOT}" /mnt/root

# download + extract
cd /mnt/root
wget -q http://os.archlinuxarm.org/os/ArchLinuxARM-rpi-armv7-latest.tar.gz
bsdtar -xpf ArchLinuxARM-rpi-armv7-latest.tar.gz -C /mnt/root
sync

# move boot files
mv /mnt/root/boot/* /mnt/boot/

# cleanup
#umount /mnt/boot /mnt/root
#rm -rf /mnt/boot /mnt/root

echo "Done. Insert SD card and boot the Pi."