#!/usr/local/bin/perl
use strict;
use warnings;

use lib "$ENV{HOME}/mylib/lib/perl5";
use HTML::TreeBuilder;
use LWP::Simple;


# Program Name:	top_speakers.pl
# Author:	XXXXX
# Purpose:	Parses the page http://perlcourse.ecorp.net/conf-mirror/conferences.oreillynet.com/speakers.html
#		and finds the speakers who had the most sessions and/or tutorials
#		Original code only found sessions or tutorials, adjusted code to find Sessions, Tutorials, BOF's & Panels
#		to match expected output per project specification

# Define debugging variable - set to positive integer to enable
my $DEBUG_FLAG = 0;

# Define variable that will contain the URL we will parse
my $URL = 'http://perlcourse.ecorp.net/conf-mirror/conferences.oreillynet.com/speakers.html';

# Define our tree using HTML::Treebuilder and parse the document
my $tree = HTML::TreeBuilder->new;
$tree->parse( get( $URL ) );

# Define our hash that will contain speaker names and their count
my %speakers;

# Define current speaker variable - used in find_speakers subroutine
my $current_speaker;

my @nodes = $tree->look_down( _tag => "a", \&find_speakers );

# If in debug mode, Print list of speaker and their total of Sessions or Tutorials
if ( $DEBUG_FLAG )
{
  foreach (sort keys %speakers)
    {
     print "$_ = ($speakers{$_})\n";
    }
}

# Set a counter to limit our results, call our sorting routine to
# sort in descending order (highest to lowest) and print results
# Exit loop once we have 3 speakers displayed.
# Technically if there are speakers with the same amount of speaking
# engagements they should be weighted equally (equal third etc) but
# this was not in the project requirements
my $counter = 0;
foreach my $key (sort hashValueDescending (keys(%speakers))) {
   print "$key\t($speakers{$key})\n";
   $counter++;
   last if $counter == 3; 
}  

# Delete tree object to free up the memory (Best practice)
$tree->delete;  

# find_speakers subroutine - finds speakers, adds their name to the %speakers hash
# then looks for Sessions, Tutorials, BOFs or Panels that the speaker is presenting
# and adds those to the total for each speaker
sub find_speakers {
  my ($element) = @_;
  my $parent = $element->parent;
  my $text   = $element->as_text;
  # Check if tag is a 'span' as this was consistent for delineating the speakers
  # throughout the document
  if ($parent->tag eq 'span'){
    print "Speaker = $text\n" if $DEBUG_FLAG;
    # add current speaker to the hash and initialize to zero
    # Note: We would need an alternative method if a speaker link appeared more than once
    $speakers{$text} = 0;
    # set current speaker 
    $current_speaker = $text;
  } 
    # Check if the parent tag is a bold element and if the text matches one
    # of our criteria -  Session, Tutorial, BOF or Panel
   elsif ($parent->tag eq 'b' 
        && $parent->as_text =~/(Session|Tutorial|BOF|Panel)/){  
    print "$1 = $text\n" if $DEBUG_FLAG;
    # add record to current speaker - set counter to current speaker contents and increment by 1
    # then assign to the $speaker hash
    my $count = $speakers{$current_speaker} + 1;
    $speakers{$current_speaker} = $count;
  } 
}

# hashValueDescending subroutine - sorts the hash in descending numerical order
# from highest down to lowest
sub hashValueDescending {
   $speakers{$b} <=> $speakers{$a};
}