#!/usr/bin/env bash

if [ -z "$1" -o -z "$2" -o -z "$3" ]
then
    # print help

    cat <<EOF

This is a helper script for make-pretty-timed-only-diff.sh.


USAGE: make-each-time-file-only-diff.sh MAKE-COMMAND NEW_FILENAME [OLD_FILENAME]

MAKE-COMMAND: The command which is used to make the library, such as
              `make` or `make -j2`

NEW_FILENAME: The name of the file to store the output of timing the
              compilation of the current state of the library

OLD_FILENAME: The name of the file to store the output of timing the
              compilation of the most recently committed state of the
              library.  If given, `git stash` is used to obtain the
              most recently committed state.  If this script is
              interrupted or finishes, `git stash pop` is used to
              restore the present state.  This means that all relevant
              files must be tracked by git to be handled properly.
EOF
fi

# in case we're run from out of git repo
DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
source "$DIR/../pushd-root.sh"

MAKECMD="$1"
NEW_FILE="$2"
OLD_FILE="$3"

# make the new version, so we get just the changes
trap "exit 1" SIGHUP SIGINT SIGTERM

$MAKECMD -k

# make the old version

# record the output of git stash, so we know whether or not something
# has changed
CHANGE="$(git stash)"
# if we're interrupted, first run `git stash pop` to clean up
trap "git stash pop && exit 1" SIGHUP SIGINT SIGTERM

# run the given `make` command, passing `TIMED=1` to get timing and
# `-k` to continue even if files fail
$MAKECMD TIMED=1 -k 2>&1 | tee "$OLD_FILE"


# make the current version
if [ ! -z "$(echo "$CHANGE" | grep "No local changes to save")" ]; then
    # there is no diff, so just copy the time file
    cp "$OLD_FILE" "$NEW_FILE"
else
    # there is a diff, so restore the changes
    git stash pop
    # now if we're interrupted, we should only exit immediately, not
    # pop more stashes
    trap "exit 1" SIGHUP SIGINT SIGTERM
    # run the given `make` command, passing `TIMED=1` to get timing
    # and `-k` to continue even if files fail
    $MAKECMD TIMED=1 -k 2>&1 | tee "$NEW_FILE"
fi

popd 1>/dev/null