disk

#!/bin/bash

set -e

IEC_SYMBOLS=("" "Ki" "Mi" "Gi" "Ti")
SI_SYMBOLS=("" "k" "M" "G" "T")
CUSTOM_SYMBOLS=("" "K" "M" "G" "T")

# human_readable(numeric_value, divisor, symbols...)
# Echoes a human readable string and return 0.
human_readable() {
	local value div
	value="$1" && shift
	div="$1" && shift

	value="$((value*10))" # mult by 10 for decimal
	for unit in "$@"
	do
		value="$((value/div))"
		if [[ "$value" -lt "$((div*10))" ]] # mult by 10 for decimal
		then
			break
		fi
	done

	# echo value with decimal dot and unit
	echo "${value:0:${#value}-1}.${value:${#value}-1:1} ${unit}B"
}

# threshold_reached()
# Return 1 if threshold is reached, 0 otherwise.
threshold_reached() {
	local value

	case "$threshold_type" in
	"percentage_free"|"percentage_avail")
		eval "$(echo value=\"\$$threshold_type\")"
		;;
	"bytes_free"|"bytes_avail")
		eval "$(echo value=\"\$_${threshold_type#bytes_*}\")"
		;;
	esac

	echo "$value < $low_threshold" | bc | grep -q 1
}

# Required a single argument
if [ $# -ne 1 ]
then
	cat <<EOF
Usage: ${0##*/} MOUNT_POINT

For a more thorough description, please refers to i3-status man page.

EOF
	exit 1
fi >&2

# Setup default values
format="${format:-%free}"
format_below_threshold="${format_below_threshold-$format}"
# format_not_mounted is not set
prefix_type="${prefix_type:-binary}"
threshold_type="${threshold_type:-percentage_avail}"
low_threshold="${low_threshold:-0}"

case "$prefix_type" in
binary)
	div=1024
	symbols=("${IEC_SYMBOLS[@]}")
	;;
decimal)
	div=1000
	symbols=("${SI_SYMBOLS[@]}")
	;;
custom)
	div=1024
	symbols=("${CUSTOM_SYMBOLS[@]}")
	;;
esac

# If not mounted, exit early
if ! mountpoint -q "$1"
then
	echo "$format_not_mounted"
	exit
fi

# Set full text format string
fulltext_format="$format"

# Get total, avail and free amount from stat and deduce used from total and free
eval "$(stat -fc "total=\$((%b * %S * 1024)); avail=\$((%a * %S* 1024)); free=\$((%f * %S* 1024)); used=\$((total-free));" "$1")"

# ... and calculate percentages
percentage_used="$(echo  "scale=1; $used  * 100 / $total" | bc)"
percentage_free="$(echo  "scale=1; $free  * 100 / $total" | bc)"
percentage_avail="$(echo "scale=1; $avail * 100 / $total" | bc)"
percentage_used_of_avail="$(echo "scale=1; 100.0 - ($avail * 100 / $total)" | bc)"

# Compute all placeholders values
_total="$(human_readable "$total" "$div" "${symbols[@]}")"
_free="$(human_readable  "$free"  "$div" "${symbols[@]}")"
_avail="$(human_readable "$avail" "$div" "${symbols[@]}")"
_used="$(human_readable  "$used"  "$div" "${symbols[@]}")"
_percentage_used="$percentage_used%"
_percentage_free="$percentage_free%"
_percentage_avail="$percentage_avail%"
_percentage_used_of_avail="$percentage_used_of_avail%"

# Check for threshold to update formatted string
if threshold_reached
then
	threshold=true
	fulltext_format="$format_below_threshold"
fi

# Update full text (first line)
eval "$(echo "echo \"${fulltext_format//%/\$_}\"")"

# Update text color if threshold is reached
if [[ $threshold ]]
then
	echo           # empty short text (second line)
	echo "#ff0000" # text color (third line)
	               # no background color (four line)
fi