From a781daf79ad6d3a3dfec09ac61e8dcc4c8cc1c48 Mon Sep 17 00:00:00 2001
From: Jason Woofenden <jason@jasonwoof.com>
Date: Wed, 4 Apr 2012 23:47:17 -0400
Subject: [PATCH] db_reposition: add $where arg so you can reposition a subset

---
 db.php |   22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/db.php b/db.php
index ddecff3..1bf78fd 100644
--- a/db.php
+++ b/db.php
@@ -419,8 +419,11 @@ function db_delete($table, $where = '') {
 
 define('DB_ORD_MAX', 2000000000);
 
-function db_reposition_respace($table, $field) {
-	$ids = db_get_column($table, 'id', "where $field != 0 order by $field");
+function db_reposition_respace($table, $field, $where = '') {
+	if($where) {
+		$andand = " && ($where) ";
+	}
+	$ids = db_get_column($table, 'id', "where $field != 0 $andand order by $field");
 	$c = count($ids);
 	if(!$c) {
 		# should never happen
@@ -442,10 +445,13 @@ function db_reposition_respace($table, $field) {
 #
 # return value is the "ord" value you should set/insert into your database
 
-function db_reposition($table, $row_id, $new_pos, $field = 'ord', $pretty = 'same as $table', $renumbered_already = false) {
+function db_reposition($table, $row_id, $new_pos, $field = 'ord', $pretty = 'same as $table', $where = '', $renumbered_already = false) {
 	if($pretty == 'same as $table') {
 		$pretty = $table;
 	}
+	if($where) {
+		$andand = " && ($where) ";
+	}
 
 	if($new_pos === 'ignored') {
 		# not sorted
@@ -454,7 +460,7 @@ function db_reposition($table, $row_id, $new_pos, $field = 'ord', $pretty = 'sam
 
 	# strategy: calculate $prev_ord and $next_ord. If there's no space between, renumber and recurse
 	if($new_pos == '0') {
-		$row = db_get_row($table, "id,$field", "where $field != 0 order by $field limit 1");
+		$row = db_get_row($table, "id,$field", "where $field != 0 $andand order by $field limit 1");
 		if($row) {
 			list($first_row_id, $first_row_ord) = $row;
 			if($first_row_id == $row_id) {
@@ -470,10 +476,10 @@ function db_reposition($table, $row_id, $new_pos, $field = 'ord', $pretty = 'sam
 		$prev_ord = 0;
 	} else {
 		$new_pos = format_int_0($new_pos);
-		$rows = db_get_rows($table, "id,$field", "where $field != 0 order by $field limit %i,2", $new_pos - 1);
+		$rows = db_get_rows($table, "id,$field", "where $field != 0 $andand order by $field limit %i,2", $new_pos - 1);
 		if(!$rows) {
 			message("Sorry, couldn't find the $pretty you asked to put this $pretty after. Putting it first instead.");
-			return db_reposition($table, $row_id, '0', $field, $pretty);
+			return db_reposition($table, $row_id, '0', $field, $pretty, $where);
 		} else {
 			list($prev_id, $prev_ord) = $rows[0];
 			if($prev_id == $row_id) {
@@ -497,8 +503,8 @@ function db_reposition($table, $row_id, $new_pos, $field = 'ord', $pretty = 'sam
 			message("Programmer error in $pretty ordering code. Please tell your website administrator.");
 			return '' . rand(2, DB_ORD_MAX - 2); # reasonably unlikely to be the same as some other ord
 		}
-		db_reposition_respace($table, $field);
-		return db_reposition($table, $row_id, $new_pos, $field, $pretty, $renumbered_already = true);
+		db_reposition_respace($table, $field, $where);
+		return db_reposition($table, $row_id, $new_pos, $field, $pretty, $where, $renumbered_already = true);
 	} else {
 		return $prev_ord + round(($next_ord - $prev_ord) / 2);
 	}
-- 
1.7.10.4