#!/usr/bin/perl

use LWP::UserAgent;
use HTML::Form;
use Date::Manip;          # CPAN
use HTML::TreeBuilder;    # CPAN

######################################################################
# Send the password form and check for success.
#
# @param $form the form to send.

sub send_pw {

    my $form     = shift;

    print "sending password\n";

    # [1] Build request from the form
    my $request = $form->click();
    
    # [2] Pass request to the user agent and get a response back
    my $response = $ua->request($request);
    
    # [3] Check the outcome of the response
    if (! $response->is_success) {
        die "Can't send password.\n";
    }

    return 0;
}

######################################################################
# Bid for an auction.
#
# @param $username the user
# @param $password the password of this user
# @param $form the form to submit.

sub send_bid {

    my $ret;

    my $username = shift;
    my $password = shift;
    my $form     = shift;

    # we start without sucess... 
    $ret = 1;

    print "sending bid\n";

    # [1] Build request from the form
    my $request = $form->click();
    
    # [2] Pass request to the user agent and get a response back
    my $response = $ua->request($request);
    
    # [3] Check the outcome of the response
    if (! $response->is_success) {
        die "Can't send bid.\n";
    }

    # [4] Get all forms and find the right one to set the username and password
    @forms = HTML::Form->parse($response->content, $response->base());
    foreach $form (@forms) {
        $username_input = $form->find_input("user");
        $password_input = $form->find_input("pass");
        # the form must have a user and password field
        if ( $username_input != undef && $password_input != undef ) {
            $username_input->value($username);
            $password_input->value($password);
            $ret = send_pw($form);
        }
    }
    
    return $ret;
}

######################################################################
# Bid for an auction.
# 
# @param $number   the article to buy
# @param $username the user
# @param $password the password of this user
# @param $maxbid   the maximum bid

sub bid {
    my $ret;

    my $number   = shift;
    my $username = shift;
    my $password = shift;
    my $maxbid   = shift;

    # we start without sucess... 
    $ret = 1;

    # [1] Create a request
    my $request = HTTP::Request->new(GET => 'http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=' . $number);
    
    # [2] Pass request to the user agent and get a response back
    my $response = $ua->request($request);
    
    # [3] Check the outcome of the response
    if (! $response->is_success) {
        die "Can't contact ebay for article.\n";
    }

    # [4] Get all forms and find the right one
    @forms = HTML::Form->parse($response->content, $response->base());
    foreach $form (@forms) {
        $maxbid_input = $form->find_input("maxbid");
        # the form must contain a field named "maxbid".
        if ( defined($maxbid_input) ) {
            $maxbid_input->value($maxbid);
            $ret = send_bid($username, $password, $form);
        }
    }

    return $ret;
}

######################################################################
# Get the number of seconds until the auction ends.
#
# @param $number the item number of the auction

sub get_secs_until_end_of_auction {
    my $number = shift;
    my $remaining_secs = 1000;

    # [1] Create a request
    my $request = HTTP::Request->new(GET => 'http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=' . $number);
    
    # [2] Pass request to the user agent and get a response back
    my $response = $ua->request($request);
    
    # [3] Check the outcome of the response
    if (! $response->is_success) {
        warn "Can't contact ebay for articel.\n";
    }

    # [4] Build the HTML tree and look for the title element
    my $tree = HTML::TreeBuilder->new;
    $tree->parse($response->content);
    my $title = $tree->look_down('_tag', 'title');
    if ($title) {
        # the title contains something like: 
        # "eBay item 27323776XX (Ends Jun-04-03 14:04:04 PDT) - Laptop..."
        $title_string = $title->as_text; 

        # [4.1] Find out the date inside the brackets
        if ( $title_string =~ /\(\S+\s+(.*)\)/ ) {
            
            # [4.1.1] Parse the date of the auction and "today"
            $secs_to_end = &UnixDate($1,"%s");
            $secs_to_now = &UnixDate("today","%s");
            
            # [4.1.2] Compute the remaining seconds
            $remaining_secs = $secs_to_end - $secs_to_now;
        }
    } else {
        warn "No title in article";
    }
    $tree->delete;
    
    return $remaining_secs;
}

######################################################################
# Wait for the end of the auction.
#
# @param $number the item number of the auction
#

sub wait_for_end_of_auction {
    my $ret;

    my $number   = shift;

    print "waiting for end of auction... ";

    # [1] Get the number of seconds until the auction ends
    $secs = get_secs_until_end_of_auction($number);

    # [2] Wait this time
    while ($secs > 400 ) {
        print " $secs";
        sleep(300);

        # [2.1] resynchronize again
        $secs = get_secs_until_end_of_auction($number);
    }
    
    # [3] add 10 more seconds until the auction ends
    $secs = $secs + 10;

    # [4] ... and wait
    print "Last sleep for $secs seconds.\n";
    sleep($secs);
}

######################################################################
# Print the winner of the auction.
#
# @param $number the item number of the auction

sub print_winner_of_auction {
    my $number = shift;
    my $remaining_secs = 1000;

    # [1] Create a request
    my $request = HTTP::Request->new(GET => 'http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=' . $number);
    
    # [2] Pass request to the user agent and get a response back
    my $response = $ua->request($request);
    
    # [3] Check the outcome of the response
    if (! $response->is_success) {
        warn "Can't contact ebay for articel.\n";
    }

    # [4] Build the HTML tree and look for the title element
    if ( $response->content =~ /ReturnUserEmail&requested=(\w+)&/ ) {
        print "The winner is: $1\n";
    } else {
        warn "No winner could be found.";
    }
}

$| = 1;

if ( $#ARGV != 3 ) {
    die "usage: ebay.pl number username password maximum-bid\n";
}

$number   = shift;
$username = shift;
$password = shift;
$maxbid   = shift;

# [1] Build the user agent
$ua = LWP::UserAgent->new;

# [2] Bid 
bid($number, $username, $password, $maxbid);

# [3] Wait for end
wait_for_end_of_auction($number);

# [4] Check for success
print_winner_of_auction($number);