#!/bin/bash

set -euo pipefail

if [[ $# -ne 2 ]]; then
   echo "$0 {force_crc} {crc32}"
   exit 1
fi
TOOL=$1
CRC32=$2
TEST_DIR=$(mktemp -d)

# Delete temporary directory and exit with nonzero status.
function die
{
   echo "$1"
   rm -rf "$TEST_DIR"
   exit 1
}

# Run tool and compare output against the expected CRC.
function run_test
{
   expected_crc=$2

   "$TOOL" "$expected_crc" "$TEST_DIR/input.txt" "$TEST_DIR/input.map" \
      > "$TEST_DIR/actual.txt" \
      || die "$1 (run)"

   actual_crc=$("$CRC32" "$TEST_DIR/actual.txt")
   if [[ "$expected_crc" != "$actual_crc" ]]; then
      die "$1 (check)"
   fi
}


# Try empty input.  We will get an error status because this tool can't
# handle empty files, but we want to see that it doesn't crash.
"$TOOL" 00000000 /dev/null /dev/null && die "$LINENO: empty"

# Check that mapping file with different size from input is rejected.
echo "1" > "$TEST_DIR/input.txt"
echo "12" > "$TEST_DIR/input.map"
"$TOOL" 00000000 "$TEST_DIR/input.txt" "$TEST_DIR/input.map" \
   > /dev/null 2>&1 && die "$LINENO: mismatched map size"

# Test basic CRC32 computation using CRC32 quines.
echo "XXXXXXXX" > "$TEST_DIR/input.txt"
for q in 58a8a1b9 86319a79; do
   echo "$q" > "$TEST_DIR/expected.txt"

   "$TOOL" "$q" "$TEST_DIR/input.txt" "$TEST_DIR/input.txt" \
      > "$TEST_DIR/actual.txt" \
      || die "$LINENO: insert $q"

   diff "$TEST_DIR/expected.txt" "$TEST_DIR/actual.txt" \
      || die "$LINENO: compare $q"

   "$TOOL" "$q" "$TEST_DIR/expected.txt" "$TEST_DIR/expected.txt" \
      > "$TEST_DIR/actual.txt" \
      || die "$LINENO: verify $q"

   diff "$TEST_DIR/expected.txt" "$TEST_DIR/actual.txt" \
      || die "$LINENO: compare $q"
done

# Fix up a few bytes to reach target CRC.
echo -n "1234567890" > "$TEST_DIR/input.txt"
echo -n "X........." > "$TEST_DIR/input.map"
run_test "$LINENO: fix prefix 1 byte" "01b32f0d"

echo -n "XX........" > "$TEST_DIR/input.map"
run_test "$LINENO: fix prefix 2 bytes" "94fe51b9"

echo -n ".........X" > "$TEST_DIR/input.map"
run_test "$LINENO: fix suffix 1 byte" "4cad8e17"

echo -n "........XX" > "$TEST_DIR/input.map"
run_test "$LINENO: fix suffix 2 bytes" "ceb6164e"

echo -n "....X....." > "$TEST_DIR/input.map"
run_test "$LINENO: fix middle 1 byte" "be5aee68"

echo -n "....XX...." > "$TEST_DIR/input.map"
run_test "$LINENO: fix middle 2 bytes" "6c9aa5fa"

echo -n "..XX..XX.." > "$TEST_DIR/input.map"
run_test "$LINENO: fix scattered bytes" "4be0bb66"

# Insert CRC to a small files with contiguous region for adjustment.
echo -n "...|...|...|...|" > "$TEST_DIR/input.txt"
echo -n "XXXXXXXX...XXXXX" > "$TEST_DIR/input.map"
run_test "$LINENO: adjust suffix" "12345678"

echo -n "XXXXX...XXXXXXXX" > "$TEST_DIR/input.map"
run_test "$LINENO: adjust prefix" "56780000"

# Check that original input characters are used first.
#
# Space is not used as replacement characters unless the original file
# had them, so if we didn't use the original characters, we won't be
# able to adjust this file to match the expected CRC.
echo "   " > "$TEST_DIR/input.txt"
echo "XXX" > "$TEST_DIR/input.map"
run_test "$LINENO: prefer original characters" "cc6afb7e"

rm -rf "$TEST_DIR"
exit 0