From 67069e07f8926e559ecef408e1be3bfcc8ab4416 Mon Sep 17 00:00:00 2001
From: Christian Boltz <postfixadmin@cboltz.de>
Date: Sat, 9 Apr 2011 22:37:11 +0000
Subject: [PATCH] functions.inc.php: - new function create_page_browser()

Function to create the page browser index ("a-c, d-h, ...") with light
speed (at least when compared with the current code that can take several
minutes(!) for people with lots of mailboxes or aliases).

At the moment, it only works with MySQL, has several big TODO notes
(including notices how to implement the PostgreSQL query) and is not
yet actively used.


git-svn-id: https://svn.code.sf.net/p/postfixadmin/code/trunk@1022 a1433add-5e2c-0410-b055-b7f2511e0802
---
 functions.inc.php | 50 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)

diff --git a/functions.inc.php b/functions.inc.php
index 9d5c2d08..ff9846be 100644
--- a/functions.inc.php
+++ b/functions.inc.php
@@ -566,6 +566,56 @@ function get_domain_properties ($domain)
 }
 
 
+/**
+ * create_page_browser
+ * Action: Get page browser for a long list of mailboxes, aliases etc.
+ * Call: $pagebrowser = create_page_browser('table.field', 'query', 50)   # replaces $param = $_GET['param']
+ *
+ *  @param String idxfield - database field name to use as title
+ *  @param String query - core part of the query (starting at "FROM")
+ *  @param Int    item_count - number of total items (this function is lazy and doesn't want to count itsself ;-)
+ *  @return String 
+ */
+function create_page_browser($idxfield, $query, $item_count) {
+    global $CONF;
+    $page_size = $CONF['page_size'];
+    $label_len = 2;
+    $pagebrowser = array();
+
+# TODO: item_count is undefined on search results
+#    if ( $item_count <= $page_size ) return array(); # very short list - no pagebrowser needed
+
+    $initcount = "SET @row=-1";
+    $result = db_query($initcount);
+
+    $last_in_page = $page_size - 1;
+    $query = "SELECT * FROM (SELECT $idxfield AS label, @row := @row + 1 AS row $query ) idx WHERE MOD(idx.row, $page_size) IN (0,$last_in_page)"; 
+
+# TODO: $query is MySQL-specific
+
+# PostgreSQL: 
+# http://www.postgresql.org/docs/8.1/static/sql-createsequence.html
+# http://www.postgresonline.com/journal/archives/79-Simulating-Row-Number-in-PostgreSQL-Pre-8.4.html
+# http://www.pg-forum.de/sql/1518-nummerierung-der-abfrageergebnisse.html
+# CREATE TEMPORARY SEQUENCE foo MINVALUE 0 MAXVALUE $page_size CYCLE
+# afterwards: DROP SEQUENCE foo
+
+    $result = db_query ($query);
+    if ($result['rows'] > 0) {
+        while ($row = db_array ($result['result'])) {
+            if ($row2 = db_array ($result['result'])) {
+                $label = substr($row['label'],0,$label_len) . '-' . substr($row2['label'],0,$label_len);
+                $pagebrowser[] = $label;
+            } else {
+                $label = substr($row['label'],0,$label_len) . '-' . 'ZZ';
+                # TODO: separate query for the last row - or include it in the main query (... OR row = $item_count)
+                $pagebrowser[] = $label;
+            }
+        }
+    }
+
+    return $pagebrowser;
+}
 
 //
 // get_mailbox_properties