#!/usr/bin/perl

use strict;
use warnings;
use Storable qw(retrieve);
use Encode qw(decode_utf8);
use HTML::Escape qw(escape_html);
use Time::HiRes qw(gettimeofday tv_interval);
use BSD::Resource; 

# 1. Start Benchmark Timer
my $start_time = [gettimeofday];
my $files_read = 0; # Track IO Activity

# Configuration
my $max_parallel   = 100;                    
my $lock_timeout   = 30;                    
my $max_results    = 1000;                    
my $min_query_len  = 3;                     
my $index_file     = 'search_index.dat';    
my $lock_dir       = '/tmp/search_locks';   

# Concurrency control
mkdir $lock_dir, 0777 unless -d $lock_dir;
my $active_count = 0;
my $now = time();

opendir(my $dh, $lock_dir);
while (my $file = readdir($dh)) {
    next unless $file =~ /\.lock$/;
    my $path = "$lock_dir/$file";
    my $mtime = (stat($path))[9] || 0;
    ( $now - $mtime > $lock_timeout ) ? unlink($path) : $active_count++;
}
closedir($dh);

# Too many search requests
if ($active_count >= $max_parallel) {
    print "Content-Type: text/html\n\n";
    render_html("<p>Server busy. Please try again in a few seconds.</p>", "", (localtime)[5]+1900);
    exit;
}

my $lock_file = "$lock_dir/$$.lock";
open(my $fh_lock, '>', $lock_file);
$files_read++; # IO for lock creation

my $search_text = '';
if (($ENV{QUERY_STRING} || '') =~ /^q=([^&]*)/) {
    $search_text = decode_utf8($1 // "");
    $search_text =~ s/\P{Print}//g; 
    $search_text = substr($search_text, 0, 64);
    $search_text =~ s/^\s+|\s+$//g;
}

my $safe_search_text = escape_html($search_text);
my $year = (localtime)[5] + 1900;

print "Content-Type: text/html\n\n";

if ($search_text eq '') {
    final_output("<p>Please enter a search term above.</p>");
}

if (length($search_text) < $min_query_len) {
    final_output("<p>Search term is too short. Please enter at least $min_query_len characters.</p>");
}

if (!-f $index_file) {
    final_output("<p>Search temporarily unavailable.</p>");
}

# IO for index retrieval
my $index = retrieve($index_file);
$files_read++; 

my @results;
my $found = 0;

foreach my $url (sort keys %$index) {
    last if $found >= $max_results;
    my $data = $index->{$url};

    next unless $data->{c} =~ /(.{0,40})(\Q$search_text\E)(.{0,40})/is;
    my ($before, $actual, $after) = ($1, $2, $3);
    $found++;

    $after =~ s/\s\S*$// if length($after) > 25;
    $before =~ s/^.*?\s// if length($before) > 25;

    $before = ($before =~ /\S/) ? ucfirst($before) : "";
    $actual = ($before eq "") ? ucfirst($actual) : $actual;

    my $snippet = escape_html($before) . "<b>" . escape_html($actual) . "</b>" . escape_html($after) . "...";

    push @results, { 
        path    => $url,
        title   => escape_html($data->{t}), 
        snippet => $snippet 
    };
}

my $list_html = "";
if (@results == 0) {
    $list_html = "<p>No results found for \"<b>$safe_search_text</b>\".</p>";
} else {
    $list_html = "<ul>" . join('', map { 
        "<li><a href=\"/$_->{path}\">$_->{title}</a><br><small>$_->{snippet}</small></li>" 
    } @results) . "</ul>";
}

final_output($list_html);

sub final_output {
    my ($content) = @_;
    
    # 2. Calculate Metrics just before rendering
    my $elapsed = tv_interval($start_time, [gettimeofday]);
    my $rusage  = getrusage();
    my $user_cpu   = $rusage->utime; 
    my $system_cpu = $rusage->stime; 
    my $max_rss    = $rusage->maxrss; 

    my $bench_html = <<"BENCH";
<div style="background: #f4f4f4; padding: 10px; border-radius: 5px; font-family: monospace; font-size: 0.85em; margin-top: 20px; border: 1px solid #ddd;">
    <strong>Performance Metrics:</strong><br>
    Total Time:  @{[ sprintf("%.4f", $elapsed) ]} seconds<br>
    User CPU:    $user_cpu s<br>
    System CPU:  $system_cpu s<br>
    Peak RAM:    $max_rss KB<br>
    Files Read:  $files_read (IO Activity)
</div>
BENCH

    render_html($content . $bench_html, $safe_search_text, $year);
    close($fh_lock) if $fh_lock;
    unlink($lock_file) if -f $lock_file;
    exit;
}

sub render_html {
    my ($content, $q_val, $yr) = @_;
    print <<"HTML";
<!DOCTYPE html>
<html lang="en-us">
<head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>Search</title>
    <link rel="stylesheet" href="/assets/css/main.css">
    <link rel="stylesheet" href="/assets/css/skeleton.css">
</head>
<body>
    <div id="nav-container" class="container">
        <ul id="navlist" class="left">
            <li><a href="/" class="link-decor-none">hme</a></li>
            <li><a href="/log/" class="link-decor-none">log</a></li>
            <li><a href="/projects/" class="link-decor-none">poc</a></li>
            <li><a href="/about/" class="link-decor-none">abt</a></li>
            <li class="active"><a href="/cgi-bin/find.cgi" class="link-decor-none">sws</a></li>
            <li><a href="/feed.xml" class="link-decor-none">rss</a></li>
        </ul>
    </div>
    <main class="container" id="main">
        <div class="container">
            <h2>Search</h2>
            <form action="" method="GET">
                <input id="search-box" type="text" name="q" value="$q_val">
                <input id="search-btn" type="submit" value="Search">
            </form>
            $content
        </div>
    </main>
    <div class="footer">
        <div class="container">
            <div class="twelve columns right container-2">
                <p id="footer-text">&copy; ASCIIMX - $yr</p>
            </div>
        </div>
    </div>
</body>
</html>
HTML
}