Plugin: Add a system for logging events related to pledges and contributors (#54)

Uses action hooks to capture relevant events as log entries on a per-pledge basis. This provides a running history of a pledge and can be used as an audit log if questions arise about changes to a pledge or there are weird bugs.

Fixes #39

plugins/wporg-5ftf/views/log.php

@@ -0,0 +1,55 @@
+<?php
+namespace WordPressDotOrg\FiveForTheFuture\View;
+
+/** @var array $log */
+?>
+
+<div class="5ftf-activity-log">
+	<?php if ( ! empty( $log ) ) : ?>
+
+		<table class="striped widefat">
+			<thead>
+			<tr>
+				<td>Date</td>
+				<td>Entry</td>
+				<td>User</td>
+			</tr>
+			</thead>
+			<tbody>
+			<?php foreach ( $log as $entry ) : ?>
+				<tr>
+					<td>
+						<?php echo esc_html( date( 'Y-m-d H:i:s', $entry['timestamp'] ) ); ?>
+					</td>
+					<td>
+						<?php if ( ! empty( $entry['data'] ) ) : ?>
+							<details>
+								<summary>
+									<?php echo wp_kses_data( $entry['message'] ); ?>
+								</summary>
+								<pre><?php echo esc_html( print_r( $entry['data'], true ) ); ?></pre>
+							</details>
+						<?php else : ?>
+							<?php echo wp_kses_data( $entry['message'] ); ?>
+						<?php endif; ?>
+					</td>
+					<td>
+						<?php
+						$user = get_user_by( 'id', $entry['user_id'] );
+						if ( $user ) : ?>
+							<?php echo sanitize_user( $user->user_login ); ?>
+						<?php endif; ?>
+					</td>
+				</tr>
+			<?php endforeach; ?>
+			</tbody>
+		</table>
+
+	<?php else : ?>
+
+		<p>
+			There are no log entries.
+		</p>
+
+	<?php endif; ?>
+</div>