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

# Allow all tests to be skipped, e.g. during a release build
test "${SKIP_ALL_TESTS}" = "1" && exit 77

true "${testSubject:?not set - call this from 'make check'}"
true "${workFile1:?not set - call this from 'make check'}"
true "${workFile2:?not set - call this from 'make check'}"
true "${workFile3:?not set - call this from 'make check'}"

# 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.
# We only start doing anything once the PV process below has started (the
# workFile3 check).
# NB we just export line to make shellcheck think it's used.
true > "${workFile3}"
(
while test -e "${workFile3}" && ! test -s "${workFile3}"; do sleep 0.1; done
export line; sleep 1; read -r line; sleep 1; read -r line; sleep 1
) <"${workFile1}" &
pid=$!

sleep 0.1
"${testSubject}" -P "${workFile3}" -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