#!/usr/bin/perl -w

=head1 NAME

dh_bash-completion - install bash completions for package

=cut

use strict;
use File::Find;
use Debian::Debhelper::Dh_Lib;

=head1 SYNOPSIS

B<dh_bash-completion> [S<I<debhelper options>>]

=head1 DESCRIPTION

dh_bash-completion is a debhelper program that is responsible for installing
completions for bash, usable installing the "bash-completion" package.

In order to use it, you need to pass "--with bash-completion" to debhelper and
Build-depend on bash-completion.

If a file named debian/package.bash-completion exists, then different actions
are performed, depending on its format.

It can be a proper completion snippet, and in that case it would be installed
in the completion directory, and no other actions would be performed.

It can also be a list of files, with an optionally specified name to call the
completion snippet after. The file format is as follows:

  my/path/to/foo-completion       # this would be installed as "foo-completion"
  my/path/to/bar-completion  baz  # this would be installed as "baz"

=cut

# This helper function tries to determine (using some poor man's
# heuristics) whether $file (its first and only argument) is a
# filelist containing a list of files to be installed by us, or a
# bash-completion script, which should itself be installed.
#
# If we're dealing with a filelist, return 1.  Otherwise, return 0.
sub is_filelist {
	# The file to be checked.
	my ($file) = @_;

	open (DH_FILE, '<', $file) || error("cannot read $file: $!");

	while (<DH_FILE>) {
		# Get rid of lines containing just spaces or comments.
		chomp;
		s/^\s++//;
		next if /^#/;
		s/\s++$//;

		# We always ignore/permit empty lines
		next if $_ eq '';

		# This is the heart of the script.  Here, we check for some
		# well-known idioms on bash scripts, and try to determine if
		# they're present in the file we're examining.  We assume that
		# if they are, then this means the file is a bash-completion
		# script.
		#
		# The regexes check:
		#
		# - If we're calling the bash function "complete", which is a
		#   pretty common thing to do in bash-completion scripts, or
		#
		# - If we're using the $(program) way of executing a program.
		#   We don't take into account multi-line statements.  Or
		#
		# - If we're calling the bash function "compgen", which is
		#   also a pretty common thing that bash-completion scripts
		#   do.  Or
		#
		# - If we see an "if...then" construction in the file.  We
		#   take into account multi-line statements.
		if (/(^|[|&;])\s*complete.*-[A-Za-z].*/
			|| /\$\(.*\)/
			|| /\s*compgen.*-[A-Za-z].*/
			|| /\s*if.*;.*then/s) {
			return 0;
		}
	}

	# If we reached the end, this is not a bash-completion script.
	return 1;
}

init();

my $srcdir = '.';
$srcdir = $dh{SOURCEDIR}."/" if defined $dh{SOURCEDIR};

# PROMISE: DH NOOP WITHOUT bash-completion cli-options()

PKG: foreach my $package (@{$dh{DOPACKAGES}}) {
	next if is_udeb($package);

	my $tmp = tmpdir($package);
	my $bc_dir = "$tmp/usr/share/bash-completion/completions";
	my $completions = pkgfile($package,"bash-completion");

	my @install;
	my $name;

	if ($completions) {
		install_dir($bc_dir);

		# Invoke our heuristic function to try and determine
		# if we're dealing with a filelist or with a
		# bash-completion script.
		if (!is_filelist($completions)) {
			verbose_print "detected $completions as a bash-completion script";
			install_file($completions, "$bc_dir/$package");
			next PKG
		}

		# try parsing a list of files
		@install = filedoublearray($completions);
		foreach my $set (@install) {
			my @filelist;
			my @tmp = @$set;
			if (@$set > 1) {
				$name = pop @$set;
			}
			else {
				$name = basename($tmp[0]);
			}
			verbose_print "installing $tmp[0] as $name";

			my @found;
			foreach my $glob (@$set) {
				@found = glob "$srcdir/$glob";
				if (!compat(6)) {
					# Fall back to looking into debian/tmp
					if (!@found || !-e $found[0]) {
						@found = glob "debian/tmp/$glob";
					}
				}

				if (!@found || !-e $found[0]) {
					warning "file-list parsing failed, installing as proper snippet";

					install_file($completions, "$bc_dir/$package");
					next PKG
				}
				push @filelist, @found;
			}

			if (!@filelist) {
				error("$package missing files (@$set), aborting");
			}

			foreach my $src (@filelist) {
				install_file($src, "$bc_dir/$name");
			}
		}
	}
}

=head1 SEE ALSO

L<debhelper(1)>

This program is a part of bash-completion.

L<bash(1)>

=head1 AUTHOR

David Paleino <d.paleino@gmail.com>

=cut