#!/usr/bin/perl
# Read and edit PostgreSQL config files
# vim:sw=4:et:
#
# (C) 2014-2017 Christoph Berg <myon@debian.org>
#
#  This program is free software; you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation; either version 2 of the License, or
#  (at your option) any later version.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.

use strict;
use warnings;
use Getopt::Long;
use PgCommon qw(quote_conf_value user_cluster_map read_cluster_conf_file
    read_conf_file set_conffile_value set_conf_value disable_conffile_value
    disable_conf_value cluster_exists error config_bool);

## option parsing

sub help ($;$)
{
    my ($exit, $error) = @_;
    print STDERR "Error: $error\n" if ($error);
    print "Usage:
  $0 [options] [<version> <cluster name>] [<configfile>] <command>

Options:
  -b --boolean  Format output as boolean
  -s --short    Print only value
  -v --verbose  Verbose output
  --help        This help

Commands:
  show <parameter>|all
  set <parameter> <value>
  remove <parameter>
  edit
";
    exit $exit;
}

my $boolean = 0;
my $short = 0;
my $verbose = 0;

Getopt::Long::Configure ("bundling");
help(1) unless GetOptions (
    'help' => sub { help(0); },
    'b|boolean' => \$boolean,
    's|short' => \$short,
    'v|verbose' => \$verbose,
);

# find command in argument array
my $cmdidx;
for (my $i = 0; $i < @ARGV; $i++) {
    if ($ARGV[$i] =~ /^(show|get|set|remove|delete|disable|edit)$/) {
        $cmdidx = $i;
        last;
    }
}
help(1, 'No command given') unless (defined $cmdidx);

my ($version, $cluster, $conffile);
if ($cmdidx == 0) { # operate on postgresql.conf in default cluster
    ($version, $cluster) = user_cluster_map();
    error "No default cluster found" unless ($cluster);
    $conffile = 'postgresql.conf';
} elsif ($cmdidx == 1) { # operate on given file; default cluster must exist if file is relative
    $conffile = $ARGV[0];
    unless ($conffile =~ m!^/!) {
        ($version, $cluster) = user_cluster_map();
        error "No default cluster found" unless ($cluster);
    }
} elsif ($cmdidx == 2) { # version cluster, postgresql.conf
    ($version, $cluster, $conffile) = ($ARGV[0], $ARGV[1], 'postgresql.conf');
} elsif ($cmdidx == 3) { # version cluster conffile
    ($version, $cluster, $conffile) = ($ARGV[0], $ARGV[1], $ARGV[2]);
} else {
    help(1, 'Too many arguments before command');
}

if ($cluster) { # the cluster needs to exist unless an absolute conffile was given
    error "Cluster $version $cluster does not exist"
        unless (cluster_exists $version, $cluster);
}

splice @ARGV, 0, $cmdidx; # remove everything before the command
$ARGV[0] = 'show' if ($ARGV[0] eq 'get'); # accept alternative variants of some commands
$ARGV[0] = 'remove' if ($ARGV[0] =~ /delete|disable/);

my ($cmd, $key, $value);
if ($ARGV[0] =~ /^(edit)$/) {
    help(1, "$ARGV[0] takes no argument") unless (@ARGV == 1);
    ($cmd) = @ARGV;
} elsif ($ARGV[0] =~ /^(show|remove)$/) {
    help(1, "$ARGV[0] needs exactly one argument") unless (@ARGV == 2);
    ($cmd, $key) = @ARGV;
} else {
    help(1, "$ARGV[0] needs exactly two arguments") unless (@ARGV == 3);
    ($cmd, $key, $value) = @ARGV;
}
#print "$version $cluster $conffile $cmd $key $value\n";

## main

if ($cmd eq 'show') {
    my %conf;
    if ($conffile =~ m!^/!) {
        %conf = read_conf_file ($conffile);
    } else {
        %conf = read_cluster_conf_file ($version, $cluster, $conffile);
    }

    if ($key eq 'all') {
        foreach my $k (sort keys %conf) {
            printf "%s = %s\n", $k, quote_conf_value($conf{$k});
        }
    } elsif (exists $conf{$key}) {
        $conf{$key} = config_bool($conf{$key}) ? 'on' : 'off' if ($boolean); # normalize boolean output on request
        if ($short) {
            printf "%s\n", $conf{$key};
        } else {
            printf "%s = %s\n", $key, quote_conf_value($conf{$key});
        }
    } else {
        print "# $key not found in $conffile\n" if ($verbose);
        exit 1;
    }

} elsif ($cmd eq 'set') {
    if ($conffile =~ m!^/!) {
        set_conffile_value ($conffile, $key, $value);
    } else {
        set_conf_value ($version, $cluster, $conffile, $key, $value);
    }

} elsif ($cmd eq 'remove') {
    if ($conffile =~ m!^/!) {
        disable_conffile_value ($conffile, $key);
    } else {
        disable_conf_value ($version, $cluster, $conffile, $key);
    }

} elsif ($cmd eq 'edit') {
    my $editor = 'vi';
    if ($ENV{EDITOR}) {
        ($editor) = $ENV{EDITOR} =~ /(.*)/; # untaint
    }
    if ($conffile =~ m!^/!) {
        system $editor, $conffile;
    } else {
        system $editor, "$PgCommon::confroot/$version/$cluster/$conffile";
    }
}

__END__

=head1 NAME

pg_conftool - read and edit PostgreSQL cluster configuration files

=head1 SYNOPSIS

B<pg_conftool> [I<options>] [I<version> I<cluster>] [I<configfile>] B<command>

=head1 DESCRIPTION

B<pg_conftool> allows showing and setting parameters in PostgreSQL configuration
files.

If I<version> I<cluster> is omitted, it defaults to the default cluster (see
user_clusters(5) and postgresqlrc(5)). If I<configfile> is omitted, it defaults
to B<postgresql.conf>. I<configfile> can also be a path, in which case
I<version> I<cluster> is ignored.

=head1 OPTIONS

=over 4

=item B<-b>, B<--boolean>

Format boolean value as B<on> or B<off> (not for "show all").

=item B<-s>, B<--short>

Show only the value (instead of key = value pair).

=item B<-v>, B<--verbose>

Verbose output.

=item B<--help>

Print help.

=back

=head1 COMMANDS

=over 4

=item B<show> I<parameter>|B<all>

Show a parameter, or all present in this config file.

=item B<set> I<parameter> I<value>

Set or update a parameter.

=item B<remove> I<parameter>

Remove (comment out) a parameter from a config file.

=item B<edit>

Open the config file in an editor.  Unless B<$EDITOR> is set, B<vi> is used.

=back

=head1 SEE ALSO

user_clusters(5), postgresqlrc(5)

=head1 AUTHOR

Christoph Berg L<E<lt>myon@debian.orgE<gt>>