Add optional ticket SLAs

Response/resolution targets stamped at creation from per-client/priority assignments, business-hours due date math, warn/breach alert stages via cron/ticket_sla.php, ticket list coloring, per-ticket SLA override, admin page for plans/assignments/business hours. DB update 2.5.0. No behavior change unless SLAs are assigned. Bulk reply now only counts Public replies as first response.

agent/modals/ticket/ticket_sla.php

@@ -0,0 +1,70 @@
+<?php
+
+require_once '../../../includes/modal_header.php';
+
+enforceUserPermission('module_support', 2);
+
+$ticket_id = intval($_GET['id']);
+
+$sql = mysqli_query($mysqli, "SELECT * FROM tickets
+    LEFT JOIN clients ON client_id = ticket_client_id
+    WHERE ticket_id = $ticket_id
+    LIMIT 1"
+);
+
+$row = mysqli_fetch_assoc($sql);
+$ticket_prefix = escapeHtml($row['ticket_prefix']);
+$ticket_number = intval($row['ticket_number']);
+$ticket_sla_id = intval($row['ticket_sla_id']);
+$client_id = intval($row['ticket_client_id']);
+
+if ($client_id) {
+    enforceClientAccess();
+}
+
+$sql_slas = mysqli_query($mysqli, "SELECT sla_id, sla_name FROM slas WHERE sla_archived_at IS NULL ORDER BY sla_name ASC");
+
+ob_start();
+
+?>
+
+<div class="modal-header bg-dark">
+    <h5 class="modal-title"><i class="fa fa-fw fa-stopwatch mr-2"></i>Editing SLA: <strong><?= "$ticket_prefix$ticket_number" ?></strong></h5>
+    <button type="button" class="close text-white" data-dismiss="modal">
+        <span>&times;</span>
+    </button>
+</div>
+<form action="post.php" method="post" autocomplete="off">
+    <input type="hidden" name="csrf_token" value="<?= $_SESSION['csrf_token'] ?>">
+    <input type="hidden" name="ticket_id" value="<?= $ticket_id ?>">
+
+    <div class="modal-body">
+
+        <div class="form-group">
+            <label>SLA</label>
+            <div class="input-group">
+                <div class="input-group-prepend">
+                    <span class="input-group-text"><i class="fa fa-fw fa-stopwatch"></i></span>
+                </div>
+                <select class="form-control select2" name="sla_id" required>
+                    <option value="0" <?php if ($ticket_sla_id == 0) { echo "selected"; } ?>>None</option>
+                    <?php while ($sla_row = mysqli_fetch_assoc($sql_slas)) { ?>
+                        <option value="<?= intval($sla_row['sla_id']) ?>" <?php if ($ticket_sla_id == intval($sla_row['sla_id'])) { echo "selected"; } ?>><?= escapeHtml($sla_row['sla_name']) ?></option>
+                    <?php } ?>
+                </select>
+            </div>
+            <small class="text-muted">Response and resolution targets are recalculated from the ticket's creation time.</small>
+        </div>
+
+    </div>
+
+    <div class="modal-footer">
+        <button type="submit" name="edit_ticket_sla" class="btn btn-primary text-bold"><i class="fa fa-check mr-2"></i>Save</button>
+        <button type="button" class="btn btn-light" data-dismiss="modal"><i class="fa fa-times mr-2"></i>Cancel</button>
+    </div>
+
+</form>
+
+<?php
+
+require_once '../../../includes/modal_footer.php';