This script generates a list of post with a prev next pagination to show posts of a specified day and category through urls segments

posts.php

<?php

// include("./head.inc");


/**
 * Script Example
 *
 * This script generates a prev next pagination to show posts per day of a specified date
 * The category is set by the first url segment the date in the second
 *
 * as per http://processwire.com/talk/topic/2928-pagination-by-date/
 *
 * - post template has a date field "publish_from"
 * - post template has a page field "categories" to select category pages
 * - posts template has urlSegments enabled
 * - category template with only a title field
 *
 * urls for posts for a day by a category:
 * /posts/[category]/[dd-mm-yyyy]/
 *
 * or default today posts by a category:
 * /post/[category]/
 *
 *
 */

// get category url segment and page
if($input->urlSegment1){
    $cat = $sanitizer->pageName($input->urlSegment1);
} else {
    $cat = "category1"; // default
}

$category_page = $pages->get("template=category, name=$cat");

// throw 404 when category not found
if(!$category_page->id) {
    throw new Wire404Exception("Page Not Found");
}

// get date url segment
if($input->urlSegment2) {
    $day = $sanitizer->pageName($input->urlSegment2);
} else {
    $day = date("d-m-Y", strtotime("today")); // default
}

// get post from the day x, to cover 24 hours we need a start and end time
$day_end = strtotime( $day . " 23:59:59" );
$posts_day = $pages->find("template=post, categories=$category_page, sort=-publish_date, publish_date>=$day, publish_date<=$day_end");

if(count($posts_day)){
    echo "<h2>Posts from day $day</h2>";
    echo "<ul>";
    foreach($posts_day as $post) {
        echo "<li><a href='$post->url'>$post->title</a></li>";
    }
    echo "</ul>";
}

// look for the next post in future or past
$post_prev = $pages->get("template=post, sort=-publish_date, publish_date<=" . strtotime("$day -1 second"));
$post_next = $pages->get("template=post, sort=publish_date, publish_date>=" . strtotime("$day +1 day"));

// only if posts found we output prev and/or next link
if($post_prev->id) {
    $prev_day = date("d-m-Y", strtotime($post_prev->publish_date));
    echo "<a href='{$config->urls->root}posts/$cat/$prev_day/'>prev</a> ";
}
if($post_next->id) {
    $next_day = date("d-m-Y", strtotime($post_next->publish_date));
    if($post_prev->id) echo " | ";
    echo "<a href='{$config->urls->root}posts/$cat/$next_day/'>next</a><br/>";
}


// include("./foot.inc");