#!/bin/sh
#
# Check that watching a single file descriptor works as expected.

# Dummy assignments for "shellcheck".
testSubject="${testSubject:-false}"; workFile1="${workFile1:-.tmp1}"; workFile2="${workFile2:-.tmp2}"

# Skip the test if "-d" is not available.
if ! "${testSubject}" -h | grep -Fq ' -d'; then
	echo "no \`--watchfd' / \`-d' option on this platform"
	exit 77
fi

seq 1 100 > "${workFile1}"

# Run a background process to perform a few reads from a file.
# NB we just export line to make shellcheck think it's used.
(export line; sleep 1; read -r line; sleep 1; read -r line; sleep 1) <"${workFile1}" &
pid=$!

sleep 0.1
"${testSubject}" -d "${pid}:0" -f -i 0.5 >/dev/null 2>"${workFile2}"

# Skip the test if "-d" does not work.
if grep -Fq ' -d: not available' "${workFile2}"; then
	echo "no \`--watchfd' / \`-d' option on this platform"
	exit 77
fi

# There should be at least 2 different numbers starting the output lines. 
positionsReported="$(tr '\r' '\n' < "${workFile2}" | awk '{print $1}' | sort -n | uniq)"
differentNumbers="$(printf "%s\n" "${positionsReported}" | grep -Ec .)"
if ! test "${differentNumbers}" -gt 1; then
	printf "%s\n" "Expected at least 2 different numbers to be output"
	printf "%s:\n%s\n" "Positions reported" "${positionsReported}"
	printf "%s: %s\n" "Number of different values seen" "${differentNumbers}"
	printf "%s\n" "Raw output:"
	tr '\r' '\n' < "${workFile2}"
	exit 1
fi

exit 0