#!/bin/bash

# Find the largest device
for drive in "$@"; do
  # Count partitions on drive
  parts=${drive}?*
  # Unpartitioned devices are treated like one partition
  [[ -z "$parts" ]] && { todo+=" $drive"; continue; }

  count=$(echo $parts | wc -w)
  # Check if this is the largest device so far
  if [[ $count -gt $lgcount ]]; then
    # Add previous largest to the processing list
    [[ -n "$largest" ]] && todo+=" $largest"

    # Set new largest to the partitions in this device
    largest=$parts
    lgcount=$count
  else
    # Add this device's partitions to the processing list
    todo+=" $parts"
  fi
done

# Ensure at least one device is partitioned
[[ -z "$largest" ]] && {
  echo 'Error: Partition at least one device or use mdadm directly'
  exit 1
}

# The number of arrays is the number of partitions on the largest device
arrays=($largest)
# The other partitions are laid down like bricks, distributed among the arrays
i=0
for part in $todo; do
  arrays[$i]+=" $part"
  let i=i+1
  [[ $i -ge ${#arrays[@]} ]] && i=0
done

# Create the arrays
i=1
for array in "${arrays[@]}"; do
  mdadm --create /dev/md/${NAME-raid5}-$i -R \
    -n $(echo $array | wc -w) -l raid5 -k ppl $array || exit 1
  let i=i+1
done