#!/usr/bin/perl -w

# make_exhibit.plx

# this script reads a pair of data files, extracts information
# relating to a group of tradeshow exhibitors, and writes
# out a browseable Web-based directory of those exhibitors

use strict;

# configuration section:

my $exhibit_file  = './exhibit.txt';
my $category_file = './category.txt';

# script-wide variables:

my %listing;               # key:   company name ($co_name). 
                           # value: HTML-ized listing for this company.

my %companies_by_category; # key:   category name.
                           # value: $co_name\n$co_name\n$co_name...

# read and parse the main exhibitor file

my @listing_lines = (); # holds current listing's lines for passing
                        # to the &parse_exhibitor subroutine

open EXHIBIT, $exhibit_file
    or die "Can't open $exhibit_file for reading: $!\n";

while (<EXHIBIT>) {
    if (/^\s*$/) {
        # this line is blank (or has nothing but space chars)
        if (@listing_lines) {
            &parse_exhibitor(@listing_lines);
            @listing_lines = ();
        }
    } else {
        # this line actually has data
        push @listing_lines, $_;
    }
}

# process last batch of lines, if the file didn't have a trailing
# blank line to trigger it already.

if (@listing_lines) {
    &parse_exhibitor(@listing_lines);
}

close EXHIBIT or die "Can't close $exhibit_file after reading: $!\n";

# read and parse the category file

my @category_lines = (); # holds current category's lines for passing
                         # to the &parse_category subroutine

open CATEGORY, $category_file
    or die "Can't open $category_file for reading: $!\n";

while (<CATEGORY>) {
    if (/^\s*$/) {
        # this line is blank (or has nothing but space chars)
        if (@category_lines) {
            &parse_category(@category_lines);
            @category_lines = ();
        }
    } else {
        # this line actually has data
        push @category_lines, $_;
    }
}

# process last batch of lines, if the file didn't have a trailing
# blank line to trigger it already.

if (@category_lines) {
    &parse_category(@category_lines);
}

close CATEGORY or die "Can't close $category_file after reading: $!\n";

# output parsed data for debugging

print "LISTINGS:\n\n";

foreach my $co_name (sort keys %listing) {
    print $listing{$co_name}, "\n";
}

print "\nCATEGORIES:\n\n";

foreach my $cat (sort keys %companies_by_category) {
    print "$cat:\n\n$companies_by_category{$cat}\n";
}

# script proper ends. subroutines follow.

sub parse_exhibitor {

    # extract the relevant information about a particular
    # exhibitor and store it in the appropriate hash.
    # 
    # invoked with an array of lines read from $exhibit_file.
    # has no return value, but instead modifies the following 
    # script-wide variable:
    #
    # %listing

    my @lines = @_;

    my($co_name, $booth, $address, $address2, $phone, $fax, $email,
        $url, $description);

    my $line_count = 0;
    
    foreach my $line (@lines) {

        chomp $line;
        ++$line_count;
        
        if ($line_count == 1) {
            unless ($co_name = $line) {
                warn <<"EOF";
line_count=1, but got a false co_name. skipping exhibitor.
($exhibit_file line number $.)
EOF
                return;
            }
            
        } elsif ($line_count == 2) {

            if ($line =~ /^Booth (\d+)/) {
                $booth = $1;
            } else {
                warn <<"EOF";
line_count=2, but couldn't parse booth. skipping exhibitor.
(co_name '$co_name'. $exhibit_file line number $.)
EOF
                return;
            }

        } elsif ($line_count == 3) {

            $address = $line;

        } elsif ($line_count == 4) {

            $address2 = $line;

        } elsif ($line_count == 5) {

            if ($line =~ /^\(\d{3}\)/) {
                $phone = $line;
            } else {
                warn <<"EOF";
line_count=5, but couldn't parse phone number. skipping exhibitor.
(co_name '$co_name'. line '$line'. $exhibit_file line number $.)
EOF
                return;
            }

        } elsif ($line_count == 6){

            if ($line =~ /^(\(\d{3}\).+) \(fax\)$/) {
                $fax = $1;
            } else {
                warn <<"EOF";
line_count=6, but couldn't parse fax number. skipping exhibitor.
(co_name '$co_name'. line '$line'. $exhibit_file line number $.)
EOF
                return;
            }

        } elsif ($line =~ /^\S+@\S+$/) {

            $email = $line;

        } elsif ($line =~ /^http:\S+$/) {

            $url = $line;

        } else {

            $description .= "$line\n"; # append so that multi-line
                                       # descriptions work right
        }
    }
    
    # done cycling through @lines.

    if ($listing{$co_name}) {

        # we already have an entry in %listing for this $co_name,
        # so give an error message that we're going to be
        # writing over the old data.

                warn <<"EOF";
Parsed duplicate listing for co_name '$co_name'. Overwriting 
previous data. ($exhibit_file line number $.)
EOF
    }

    # create the %listing entry

    $listing{$co_name}  = <<"EOF";
co_name:  $co_name
booth:    $booth
address:  $address
address2: $address2
phone:    $phone
fax:      $fax
email:    $email
url:      $url

description:
$description
EOF
}

sub parse_category {

    # extract the relevant information about a particular
    # category and store it in the appropriate hashes.
    # 
    # invoked with an array of lines read from $category_file.
    # has no return value, but instead modifies this script-wide
    # variable:
    #
    # %companies_by_category

    my @lines = @_;
    my $category;
    my $line_count = 0;
    
    foreach my $line (@lines) {

        chomp $line;
        ++$line_count;

        if ($line_count == 1) {
            if ($line =~ /^\[\[(.+)\]\]$/) {
                # line looks like '[[category name]]'
                $category = $1;
            } else {
                warn <<"EOF";
line_count=1, but couldn't parse category name. skipping this category.
($category_file line number $.)
EOF
                return;
            }
            
        } elsif ($line =~ /^(.+), \d+$/) {

            my $co_name = $1;

            if ($listing{$co_name}) {
                $companies_by_category{$category} .= "$co_name\n";
            } else {
                warn <<"EOF";
parsed co_name '$co_name' from category file, but couldn't find a 
corresponding company listing. ($category_file line number $.)
EOF
            }
        
        } else {

            warn <<"EOF";
line '$line' from category file doesn't appear to be either a 
category or a company ($category_file line number $.)
EOF
        }
    }    
}