#!/bin/sh
#
# Compare QDSPC with the backing filesystem's unprivileged free blocks and the
# configured Queue reserve.  Two stat samples bracket QDSPC so unrelated small
# writes cannot turn a correct calculation into a false failure.

set -eu

queue_tool=${BONGO_QUEUE_TOOL:-/usr/bin/bongo-queuetool}
run_as=${BONGO_TEST_RUN_AS:-bongo}

if [ "$(id -un)" = "$run_as" ]; then
    as_bongo=
else
    as_bongo="sudo -n -u $run_as"
fi

set -- $($as_bongo "$queue_tool" space details)
if [ "$#" -ne 5 ]; then
    echo "STQ-03: unexpected detailed space response" >&2
    exit 1
fi
free_before=$1
free_after=$2
reserve=$3
reported=$4
block=$5

for value in "$free_before" "$free_after" "$reserve" "$reported" "$block"; do
    case "$value" in
        ''|*[!0-9]*)
            echo "STQ-03: detailed space response contains a non-integer" >&2
            exit 1
            ;;
    esac
done

expected_before=$((free_before > reserve ? free_before - reserve : 0))
expected_after=$((free_after > reserve ? free_after - reserve : 0))
lower=$expected_before
upper=$expected_after
if [ "$lower" -gt "$upper" ]; then
    lower=$expected_after
    upper=$expected_before
fi

# Permit one allocation unit at either side of the bracket.
lower=$((lower > block ? lower - block : 0))
upper=$((upper + block))

if [ "$reported" -lt "$lower" ] || [ "$reported" -gt "$upper" ]; then
    echo "STQ-03: QDSPC $reported is outside expected range $lower..$upper" >&2
    exit 1
fi

if [ "$free_before" -gt "$reserve" ] && [ "$reported" -ge "$free_before" ]; then
    echo "STQ-03: configured reserve was not subtracted" >&2
    exit 1
fi

printf 'STQ-03 PASS free-before=%s free-after=%s reserve=%s reported=%s block=%s\n' \
    "$free_before" "$free_after" "$reserve" "$reported" "$block"