#!/usr/bin/env perl

use strict;
use warnings;

use URI;
use URI::Escape;
use Digest::SHA qw(hmac_sha256_base64);
use LWP::UserAgent;
use XML::LibXML;

my $ASSOCIATE_TAG = '';
my $TOKEN         = '';
my $SECRET_KEY    = '';

my $VERSION  = '2011-08-01';
my $NS       = "http://webservices.amazon.com/AWSECommerceService/$VERSION";
my $BASE_URI = URI->new(
    'http://webservices.amazon.com/onca/xml?Service=AWSECommerceService');

my ($subject) = @ARGV or die "Usage: $0 <subject>";

for my $year (2002 .. 2012) {
    my $page      = 1;
    my $last_page = 10;
    while ($page <= $last_page) {
        my $uri = build_uri(
            $BASE_URI, $SECRET_KEY,
            ResponseGroup => 'Medium',
            Operation     => 'ItemSearch',
            SearchIndex   => 'Books',
            Sort          => 'daterank',
            Power         => "subject:$subject and subject:programming "
              . "and keyword:$subject and pubdate: $year "
              . "and language: English and not fiction",
            ItemPage => $page
        );

        my $result = fetch_uri($uri);

        my $dom = XML::LibXML->load_xml(string => $result);

        my $xc = XML::LibXML::XPathContext->new($dom->documentElement());
        $xc->registerNs('ns', $NS);

        my $books = [];

        my @nodes       = $xc->findnodes('//ns:TotalPages');
        my $total_pages = $nodes[0]->textContent;
        if ($total_pages > 10) {
            die "TotalPage = $total_pages";
        }
        else {
            warn "$year: $page/$total_pages";
            $last_page = $total_pages;
        }

        @nodes = $xc->findnodes('//ns:ItemAttributes');
        foreach my $node (@nodes) {
            my @children = $node->childNodes;

            my $book = {};
            foreach my $child (@children) {
                $book->{$child->nodeName} = $child->textContent || '';
            }

            push @$books, $book;
        }

        foreach my $book (@$books) {
            next unless $book->{Title}   =~ m/$subject/i;
            next unless $book->{Binding} =~ m/(?:paperback|hardcover)/i;

            next if $book->{Title} =~ m/catalyst|rails|sinatra|django/i;

            print join ';', $book->{PublicationDate}, $book->{Title},
              ($book->{Edition} || ''), "\n";
        }

        $page++;
        sleep 1;
    }
}

sub fetch_uri {
    my ($uri) = @_;

    my $ua       = LWP::UserAgent->new();
    my $response = $ua->get($uri);

    if ($response->is_success) {
        return $response->decoded_content;
    }
    else {
        die $response->status_line;
    }
}

sub build_uri {
    my ($uri, $secret, %params) = @_;

    $uri->query_form(
        'Service'        => 'AWSECommerceService',
        'AWSAccessKeyId' => $TOKEN,
        'Version'        => $VERSION,
        'AssociateTag'   => $ASSOCIATE_TAG,
        map { $_, $params{$_} } sort keys %params,
    );

    return sign_request($uri, $secret);
}

# Taken from Net::Amazon
sub sign_request {
    my ($uri, $secret) = @_;

    # This assumes no duplicated keys. Safe assumption?
    my %query = $uri->query_form;
    my @now   = gmtime;
    $query{Timestamp} ||= sprintf(
        '%04d-%02d-%02dT%02d:%02d:%02dZ',
        $now[5] + 1900,
        $now[4] + 1,
        @now[3, 2, 1, 0]
    );
    my $qstring = join '&',
      map { "$_=" . uri_escape($query{$_}, "^A-Za-z0-9\-_.~") }
      sort keys %query;

    # Use chr(10), not "\n" which varies by platform
    my $signme = join chr(10), "GET", $uri->host, $uri->path, $qstring;
    my $sig = hmac_sha256_base64($signme, $SECRET_KEY);

    # Digest does not properly pad b64 strings
    $sig .= '=' while length($sig) % 4;
    $sig = uri_escape($sig, "^A-Za-z0-9\-_.~");
    $qstring .= "&Signature=$sig";
    $uri->query($qstring);
    return $uri;
}