<?php

# This program is in the public domain within the United States. Additionally,
# we waive copyright and related rights in the work worldwide through the CC0
# 1.0 Universal public domain dedication, which can be found at
# http://creativecommons.org/publicdomain/zero/1.0/


# to run this test:
#
# option 1: with wfpl-cms
#
#     set up wfpl-cms
#
#     copy/rename this file to test_db_reposition.php in your main dir
#
#     visit http://yourdomain.tld/test_db_reposition
#
#     refresh to test more times
#
#     drop the "test_db_reposition" table when you're done
#
# option 2:
#
#     require inc/wfpl/db.php
#     function message($msg) { print "$msg\n"; }
#     db_connect(...)
#     test_db_reposition_main()


function test_db_reposition_main () {
	db_send_query(
		'create table if not exists test_db_reposition ('
		. ' id int unique auto_increment,'
		. ' ord int(11) not null default 0'
		. ')'
	);
	db_delete('test_db_reposition');
	$ids = [];
	for ($i = 0; $i < 10; ++$i) {
		db_insert('test_db_reposition', 'ord', $i + 1);
		$ids[] = db_auto_id();
	}

	$max_tests = 2000;
	for ($tests = 0; $tests < $max_tests; ++$tests) {
		# decide which one to move, and to where
		$to = $from = rand(0, 9);
		while ($to === $from) {
			if ($tests < $max_tests / 3) {
				# full range (respace rare)
				$to = rand(0, 10);
			} elseif ($tests < $max_tests / 3 * 2) {
				# never place first (respaces)
				$to = rand(1, 10);
			} else {
				# never place last (respaces)
				$to = rand(0, 9);
			}
		}

		#message("from: $from (id " . $ids[$from] . "), to: $to");

		# move it in the db
		$new_ord = db_reposition(
			'test_db_reposition', # table
			$ids[$from], # id of row to move
			$to, # position to move it to (0 for first, 1 for 2nd, etc)
		);
		db_update('test_db_reposition', 'ord', $new_ord, 'where id=%i', $ids[$from]);

		# move it in our cache
		$moving = array_splice($ids, $from, 1);
		array_splice(
			$ids, # array to operate on
			($to > $from) ? ($to - 1) : ($to), # adjust if moving into the part we moved in the first splice
			0, # don't delete anything
			$moving # insert these
		);

		# check if it matches
		if (($tests % 10) === 9) {
			$db_ids = db_get_column('test_db_reposition', 'id', 'order by ord');
			for ($i = 0; $i < 10; ++$i) {
				if ($ids[$i] != $db_ids[$i]) {
					message('fail');
					return;
				}
			}
		}
	}
	message("pass! $max_tests repositions checked every 10");
}