#!/usr/bin/env perl
################################################################################
# WeBWorK Online Homework Delivery System
# Copyright © 2000-2003 The WeBWorK Project, http://openwebwork.sf.net/
# $CVSHeader: webwork-modperl/bin/wwaddindexing,v 1.1 2004/09/28 01:23:01 sh002i Exp $
# 
# This program is free software; you can redistribute it and/or modify it under
# the terms of either: (a) the GNU General Public License as published by the
# Free Software Foundation; either version 2, or (at your option) any later
# version, or (b) the "Artistic License" which comes with this package.
# 
# 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 either the GNU General Public License or the
# Artistic License for more details.
################################################################################

=head1 NAME

wwaddindexing - add indices to an existing sql_single course.

=head1 SYNOPSIS

 wwaddindexing COURSEID

=head1 DESCRIPTION

Adds indices to the course named COURSEID. The course must use the sql_single
database layout.

=cut

BEGIN {
	# hide arguments (there could be passwords there!)
	$0 = "$0";
}

use strict;
use warnings;
use DBI;

BEGIN {
	die "WEBWORK_ROOT not found in environment.\n"
		unless exists $ENV{WEBWORK_ROOT};
}

use lib "$ENV{WEBWORK_ROOT}/lib";
use WeBWorK::CourseEnvironment;
use WeBWorK::DB;
use WeBWorK::Utils qw/runtime_use/;
use WeBWorK::Utils::CourseManagement qw/dbLayoutSQLSources/;

sub usage {
	print STDERR "usage: $0 COURSEID \n";
	exit;
}

sub usage_error {
	print STDERR "$0: @_\n";
	usage();
}

# get command-line options
my ($courseID) = @ARGV;

# perform sanity check
usage_error("must specify COURSEID.") unless $courseID and $courseID ne "";

# bring up a minimal course environment
my $ce = WeBWorK::CourseEnvironment->new({
	webwork_dir => $ENV{WEBWORK_ROOT},
	courseName => $courseID,
});

# make sure the course actually uses the 'sql_single' layout
usage_error("$courseID: does not use 'sql_single' database layout.")
	unless $ce->{dbLayoutName} eq "sql_single";

# get database layout source data
my %sources = dbLayoutSQLSources($ce->{dbLayout});

foreach my $source (keys %sources) {
	my %source = %{$sources{$source}};
	my @tables = @{$source{tables}};
	my $username = $source{username};
	my $password = $source{password};
	
	my $dbh = DBI->connect($source, $username, $password);
	
	foreach my $table (@tables) {
		# this stuff straight out of sql_single.pm
		my %table = %{ $ce->{dbLayout}{$table} };
		my %params = %{ $table{params} };
		
		my $source = $table{source};
		my $tableOverride = $params{tableOverride};
		my $recordClass = $table{record};
		
		runtime_use($recordClass);
		my @fields = $recordClass->FIELDS;
		my @keyfields = $recordClass->KEYFIELDS;
		
		if (exists $params{fieldOverride}) {
			my %fieldOverride = %{ $params{fieldOverride} };
			foreach my $field (@fields) {
				$field = $fieldOverride{$field} if exists $fieldOverride{$field};
			}
		}
		
		my @fieldList;
		foreach my $start (0 .. $#keyfields) {
			my $line = "ADD INDEX ( ";
			$line .= join(", ", map { "`$_`(16)" } @keyfields[$start .. $#keyfields]);
			$line .= " )";
			push @fieldList, $line;
		}
		my $fieldString = join(", ", @fieldList);
		
		my $tableName = $tableOverride || $table;
		my $stmt = "ALTER TABLE `$tableName` $fieldString;";
		
		unless ($dbh->do($stmt)) {
			die "An error occured while trying to modify the course database.\n",
				"It is possible that the course database is in an inconsistent state.\n",
				"The DBI error message was:\n\n",
				$dbh->errstr, "\n";
		}
	}
	
	$dbh->disconnect;
}

=head1 AUTHOR

Written by Sam Hathaway, hathaway at users.sourceforge.net.

=cut