#!/usr/bin/env bash
#
# Arrrange for all shell scripts to obtain the common libraries
# not via the current working directory, but rather realpath $0, by:
#
#  1. Checking that no shell scripts have ad hoc `.` or `source`'s
#  2. Updating/checking the standard bash-utils.sh include stanza.
#   
# Usage;
#   update-shell-includes [--check] --all | [--] FILE...
#
# To edit the standard shell script stanza, edit it here in this script!

set -euo pipefail

# this include stanza is automatically maintained by update-shell-includes
common_dir=$(realpath "$0")
common_dir=$(dirname "$common_dir")
# shellcheck source=maint/common/bash-utils.sh
. "$common_dir"/bash-utils.sh

install=true
all=false

while [ $# != 0 ]; do
    case "$1" in
	--) shift; break ;;
	--check) install=false ;;
	--all) all=true ;;
	-*) fail "unknown option $1";;
	*) break ;;
    esac
    shift
done

case "$all.$#" in
    false.0) fail "need --all or one or more script filenames" ;;
    false.*) ;;
    true.0)
	wanted=$(
            git_grep_for_shell_script_shebangs | grep -vF "${0##*/}"
	)
        # shellcheck disable=SC2086
	set -- $wanted
	;;
    true.*) fail "script filenames not allowed with --all " ;;
esac

# create the .new files here, with cp, to preserve the permissions
for f in "$@"; do
    cp -- "$f" "$f.new"
done

errors=$(perl -we '
    use strict;
    use POSIX;

    my $msg_re = qr{this include stanza is automatically maintained};
    my $stanza_re = qr{
      ^ \s* \n                     # blank line
        \# \s* $msg_re .* \n
        (?: .* \S .* \n )+         # some non-blank lines
    }xm;

    my $bad_re = qr{
        ^ [\ \t]* (?: \. | source ) [ \t] .* (?: maint/ | bash-utils\.sh ) .*
    }xm;

    undef $/;
    sub slurp ($) {
        open F, "<", "$_[0]" or die "$_[0]: $!";
        $_ = <F>;
        F->error and die $!;
    }

    slurp(shift @ARGV);
    m{$stanza_re} or die "missing stanza in self!";

    my $stanza = $&;

    foreach my $f (@ARGV) {
        slurp($f);
        if (s{$stanza_re}{$stanza}) {
        } elsif (m{$bad_re}) {
            print "$f: bad include line, \`$&`\n";
        }
        open O, ">", "$f.new" or die "$f.new: $!";
        print O or die $!;
        close O or die $!;
    }
' "$0" "$@")

ok=true

if [ "$errors" != "" ]; then
    cat <<END >&2
errors searching/checking scripts for include stanzas:
$errors
END
    ok=false
fi

for f in "$@"; do
    if $ok && $install; then
	mv -f -- "$f.new" "$f"
    else
	set +e
	diff -u -- "$f" "$f.new"
	rc=$?
	set -e
	case "$rc" in
	    0) rm -- "$f.new" ;;
	    1) ok=false;;
	    *) fail 'diff failed';;
	esac
    fi
done

if ! $ok; then
    fail "$0 check/update failed"
fi