Ticket #5854: add-last-modified-date-to-post-columns.php

<?php
class Add_Last_Modified_Date_To_Post_Columns {

        function __construct() {
                add_filter( 'manage_posts_columns',              array( $this, 'add_column' ), 10, 2 );
                add_filter( 'manage_edit-post_sortable_columns', array( $this, 'add_sortable_column' ), 10, 2 );
                add_action( 'manage_posts_custom_column',        array( $this, 'display_column' ), 10, 2 );
                add_action( 'admin_enqueue_scripts',             array( $this, 'add_inline_style' ) );
        }

        function add_column( $posts_columns, $post_type ) {
                $posts_columns['modified'] = __( 'Last Modified' );

                return $posts_columns;
        }

        function add_sortable_column( $sortable_columns ) {
                $sortable_columns['modified'] = array( 'modified', true );

                return $sortable_columns;
        }

        function display_column( $column_name, $post_id ) {
                global $mode;

                if ( 'modified' !== $column_name ) {
                        return;
                }

                $post = get_post( $post_id );

                if ( '0000-00-00 00:00:00' == $post->post_date ) {
                        $t_time = $h_time = __( 'Unpublished' );
                } else {
                        $t_time = get_the_modified_time( __( 'Y/m/d g:i:s A' ) );
                        $m_time = $post->post_modified;
                        $time = get_post_modified_time( 'G', true, $post );

                        $time_diff = time() - $time;

                        if ( $time_diff > 0 && $time_diff < DAY_IN_SECONDS ) {
                                $h_time = sprintf( __( '%s ago' ), human_time_diff( $time ) );
                        } else {
                                $h_time = mysql2date( __( 'Y/m/d' ), $m_time );
                        }
                }

                if ( 'excerpt' === $mode ) {
                        echo $t_time;
                } else {
                        echo '<abbr title="' . $t_time . '">' . $h_time . '</abbr>';
                }
        }

        function add_inline_style( $hook_suffix ) {
                if ( 'edit.php' !== $hook_suffix ) {
                        return;
                }

                wp_add_inline_style( 'wp-admin', '.fixed .column-modified { width: 10% }' );
        }

}

new Add_Last_Modified_Date_To_Post_Columns;
?>