#!/usr/bin/perl -w
#
# Generate indexes files for the Crep's chorbook compilation. This is a much 
# simplified version from the original C programm that parse the input.
#
# Usage: mk-idx.pl SRC
#        SRC should be an .sxd file generated by the latex songs package
#

use warnings;
use strict;

sub uppercase($)
{
    my $letter = shift;
    $letter =~ tr/a-zàéèëê/A-ZAEEEE/;
    return $letter;
}

sub get_first_letter($)
{
    my $string = shift;
    $string =~ /([\w\d])/;
    my $letter = $1;
    $letter = "0-9" if ( $letter =~ /\d/ ); # group every numer into one category
    return uppercase $letter;	
}

#sub get_first_letter_wo_article($)
#{
#    my $string = shift;
#    my $letter;
#    if( $string =~ /^(The |L\'|Les |Le |La |Une |Un )/ ) # if there is an article before the name
#    {
#	$string =~ /$1([\w\d])/;
#	$letter = $1;
#    }
#    else
#    {
#	$string =~ /([\w\d])/;
#	$letter = $1;
#    }
#    $letter = "0-9" if ( $letter =~ /\d/ ); # group every numer into one category
#    return uppercase $letter;	
#}

sub usage 
{ 
    print "usage: make-index source\n";
    exit 1;
}

# Process command line
usage() unless @ARGV;
my $file = shift;

# Open file and store data before closing the file
open( FILE, $file ) or die("unable to open $file");
my @data = <FILE>;
close( FILE );

# Process data
my %table;

# Get the type of the index. Not used but we have it.
my $type = shift @data;

# Parse data and create the index table
my $item;
my $index;
my $link;
my $letter;
my $ref;

while( @data )
{
    $item = shift @data;
    unless( $item =~ /^\s*%/ ) # ignore a line starting with %
    {
	chomp $item;
	$index = shift @data;
	chomp $index;
	$link = shift @data;
	chomp $link;
    
	# Get the first letter or number of the current item
	$letter = get_first_letter $item;

	# Create empty data index if needed
	$table{$letter} = {} unless exists $table{$letter};
    	$table{$letter}{$item} = [] unless exists $table{$letter}{$item};

	# Create reference for the current item
	$ref = { num => $index, link => $link };
    
	# Add the reference to the index
	push @{$table{$letter}{$item}}, $ref;
    }
}

# Create the index formated file
my @refs;

foreach $letter ( sort keys %table )
{
    print '\begin{idxblock}{'.$letter."}\n";	
    foreach $item ( sort keys %{$table{$letter}} )
    {
	print '\idxentry{';
	print $item;
	print '}{';
	@refs = @{$table{$letter}{$item}};
	print join ("\\\\", map { "\\hyperlink{$_->{link}}{$_->{num}}" } @refs);
	print '}'."\n";
    }
    print '\end{idxblock}'."\n";
}