#!/usr/bin/env bash
#
# This script is designed to update the Copyright lines of all files
# that are going to be modified in the commit in a workspace,
# before the commit is made.
#
# If ${ws} is the pathname of a workspace, then you enable this script
# for that workspace by
#
# - compiling update_copyright.m to an executable, and
# - copying or symlinking this script to ${ws}/.git/hooks/pre-commit.
#
# The first step can be done by the command
#
#   make update_copyright
#
# The unneeded intermediate files from the first step can cleaned up
# by the command
#
#   make clean
#
# By default, this script requires the executable git_hooks/update_copyright
# to be present in the workspace. You can avoid having a duplicate copy
# of that executable in every workspace by
#
# - putting that executable in some central location, and
# - setting the environment variable UPDATE_MERCURY_COPYRIGHT
#   to invoke that executable.
#

set -e

rootdir=$( git rev-parse --show-toplevel )
if test "${UPDATE_MERCURY_COPYRIGHT}" != ""
then
    update_copyright="${UPDATE_MERCURY_COPYRIGHT}"
else
    update_copyright="${rootdir}/git_hooks/update_copyright"
fi

# Continue only if the update_copyright program is available.
command -v "${update_copyright}" > /dev/null || exit 0

# Find changed files for this commit.
changed_files=($( git diff --name-only --cached --diff-filter=ACMR ))
update_files=()
unknown_files=()

for file in "${changed_files[@]}"
do
    case ${file} in
        *.[mchly] | *.in | *.java | *Mmake*)
            update_files+=( "$file" )
            ;;
        *)
            unknown_files+=( "$file" )
            ;;
    esac
done

if test "${#unknown_files}" -gt 0
then
    update_files+=($( grep -sl 'Copyright .* Mercury [Tt]eam' "${unknown_files[@]}" \
        || true ))
fi

if test "${#update_files}" -gt 0
then
    # Accept both "Mercury team" and "Mercury Team".
    exec "${update_copyright}" --suffix ' Mercury ' -- "${update_files[@]}"
fi