// Public interfaces: convenience functions
function smd_prev($atts, $thing) {
	$atts['dir'] = 'prev';
	return smd_nearest($atts, $thing);
}
function smd_next($atts, $thing) {
	$atts['dir'] = 'next';
	return smd_nearest($atts, $thing);
}
function smd_link_to_prev($atts, $thing) {
	$atts['dir'] = 'prev';
	return smd_link_to($atts, $thing);
}
function smd_link_to_next($atts, $thing) {
	$atts['dir'] = 'next';
	return smd_link_to($atts, $thing);
}
function smd_if_start($atts, $thing) {
	$atts['dir'] = 'prev';
	return smd_if_horizon($atts, $thing);
}
function smd_if_end($atts, $thing) {
	$atts['dir'] = 'next';
	return smd_if_horizon($atts, $thing);
}

// ****************************
// Private function: not for public consumption
// ****************************
function smd_if_horizon($atts, $thing) {
	global $pretext, $thisarticle, $thiscategory, $smd_last, $smd_first, $smd_in_nearest;

	extract(lAtts(array(
		'type' => 'list',
		'logic' => 'or',
		'dir' => 'next',
		'debug' => 0,
	), $atts));

	$itout = array(); // For debug only
	$type = do_list($type);
	$out = array();
	foreach ($type as $item) {
		if ($debug) {
			$itout[] = $item;
		}
		switch ($item) {
			case 'list':
				if ($smd_in_nearest) {
					if ($dir == 'next') {
						$out[] = (empty($smd_last)) ? true : false;
					} else {
						$out[] = (empty($smd_first)) ? true : false;
					}
				}
				break;
			case 'category':
				if ($smd_in_nearest) {
					if ($dir == 'next') {
						$out[] = (!empty($smd_last) && ($smd_last['category1'] != $thisarticle['category1'] || $smd_last['category2'] != $thisarticle['category2'])) ? true : false;
					} else {
						$out[] = (!empty($smd_first) && ($smd_first['category1'] != $thisarticle['category1'] || $smd_first['category2'] != $thisarticle['category2'])) ? true : false;
					}
				} else {
					if ($dir == 'next') {
						$out[] = (!empty($thiscategory['is_last'])) ? true : false;
					} else {
						$out[] = (!empty($thiscategory['is_first'])) ? true : false;
					}
				}
				break;
			case 'author':
				if ($smd_in_nearest) {
					if ($dir == 'next') {
						$out[] = (!empty($smd_last) && $smd_last['author'] != $thisarticle['authorid']) ? true : false;
					} else {
						$out[] = (!empty($smd_first) && $smd_first['author'] != $thisarticle['authorid']) ? true : false;
					}
				} else {
					// Not possible since author lists are not permitted in TXP
				}
				break;
			case 'cat1':
			case 'category1':
				if ($smd_in_nearest) {
					if ($dir == 'next') {
						$out[] = (!empty($smd_last) && $smd_last['category1'] != $thisarticle['category1']) ? true : false;
					} else {
						$out[] = (!empty($smd_first) && $smd_first['category1'] != $thisarticle['category1']) ? true : false;
					}
				} else {
					if ($dir == 'next') {
						$out[] = (!empty($thiscategory['is_last'])) ? true : false;
					} else {
						$out[] = (!empty($thiscategory['is_first'])) ? true : false;
					}
				}
				break;
			case 'cat2':
			case 'category2':
				if ($smd_in_nearest) {
					if ($dir == 'next') {
						$out[] = (!empty($smd_last) && $smd_last['category2'] != $thisarticle['category2']) ? true : false;
					} else {
						$out[] = (!empty($smd_first) && $smd_first['category2'] != $thisarticle['category2']) ? true : false;
					}
				} else {
					if ($dir == 'next') {
						$out[] = (!empty($thiscategory['is_last'])) ? true : false;
					} else {
						$out[] = (!empty($thiscategory['is_first'])) ? true : false;
					}
				}
				break;
			case 'section':
			default:
				if ($smd_in_nearest) {
					if ($dir == 'next') {
						$out[] = (!empty($smd_last) && $smd_last['section'] != $thisarticle['section']) ? true : false;
					} else {
						$out[] = (!empty($smd_first) && $smd_first['section'] != $thisarticle['section']) ? true : false;
					}
				} else {
					if ($dir == 'next') {
						$out[] = empty($pretext['next_id']) ? true : false;
					} else {
						$out[] = empty($pretext['prev_id']) ? true : false;
					}
				}
				break;
		}
	}
	if ($debug) {
		echo '++ TEST RESULTS ++';
		dmp($itout);
		dmp($out);
	}
	$res = ($out) ? true : false;
	if (strtolower($logic) == "and" && in_array(false, $out)) {
		$res = false;
	}
	if (strtolower($logic) == "or" && !in_array(true, $out)) {
		$res = false;
	}
	if ($debug) {
		echo '++ FINAL RESULT ++';
		dmp($res);
	}
	return parse(EvalElse($thing, $res));
}

// ****************************
// Private function: not for public consumption
// ****************************
function smd_nearest($atts, $thing) {
	global $pretext, $thisarticle, $thiscategory, $prefs, $next_id, $prev_id, $next_title, $prev_title, $smd_last, $smd_first, $smd_in_nearest;

	extract(lAtts(array(
		'section' => $pretext['s'],
		'category' => $pretext['c'],
		'author' => $pretext['author'],
		'realname' => '',
		'status' => '4',
		'time' => 'any', // any, future, past
		'datasort' => 'section, category1, category2, author',
		'timesort' => 'posted',
		'form' => '',
		'dir' => 'next', // Set by wrapper tags
		'debug' => 0,
	), $atts));

	extract($prefs);
	$smd_in_nearest = true;

	$thing = (empty($form)) ? $thing : fetch_form($form);
	$expired = ($publish_expired_articles) ? '' : ' AND (now() <= Expires or Expires = '.NULLDATETIME.')';
	$safe_name = safe_pfx('textpattern');

	// Filters
	$catSQL = $secSQL = $authSQL = '';
	if($category) {
		$catSQL = doQuote(join("','", doSlash(do_list($category))));
		$catSQL = ' AND ( Category1 IN ('.$catSQL.') OR Category2 IN ('.$catSQL.') ) ';
	}
	if($section) {
		$secSQL = ' AND Section IN ('.doQuote(join("','", doSlash(do_list($section)))).') ';
	}
	if($realname) {
		$author = join(',', safe_column('name', 'txp_users', 'RealName IN ('. doQuote(join("','", doSlash(doArray(do_list($realname), 'urldecode')))) .')' ));
	}
	if($author) {
		$authSQL = ' AND AuthorID IN ('.doQuote(join("','", doSlash(do_list($author)))).') ';
	}
	$status = do_list($status);
	$stati = array();
	foreach ($status as $stat) {
		if (empty($stat)) {
			continue;
		} else if (is_numeric($stat)) {
			$stati[] = $stat;
		} else {
			$stati[] = getStatusNum($stat);
		}
	}
	$statSQL = 'Status IN ('.join(',', $stati).')';
	$timeSQL = '';
	switch($time) {
		case "any" : break;
		case "future" : $timeSQL = " AND Posted > now()"; break;
		default : $timeSQL = " AND Posted < now()"; break; // The past
	}

	// Sort
	$sorder = (($dir=='next') ? ' DESC' : ' ASC'); // Negative logic to avoid lookahead: the "last" row seen is always the one required
	$orderby = array();
	if ($datasort) {
		$datasort = do_list($datasort);
		foreach ($datasort as $item) {
			switch($item) {
				case 'section':
					if ($section) {
						$orderby[] = 'Section'.$sorder;
					}
					break;
				case 'category':
					if ($category) {
						$orderby[] = 'Category1'.$sorder;
						$orderby[] = 'Category2'.$sorder;
					}
					break;
				case 'category1':
					if ($category) {
						$orderby[] = 'Category1'.$sorder;
					}
					break;
				case 'category2':
					if ($category) {
						$orderby[] = 'Category2'.$sorder;
					}
					break;
				case 'author':
					if ($author) {
						$orderby[] = 'AuthorID'.$sorder;
					}
					break;
			}
		}
	}
	if ($timesort) {
		$timesort = do_list($timesort);
		foreach ($timesort as $item) {
			switch(strtolower($item)) {
				case 'lastmod':
					$orderby[] = 'LastMod'.$sorder;
					break;
				case 'expires':
					$orderby[] = 'Expires'.$sorder;
					break;
				case 'posted':
				default:
					$orderby[] = 'Posted'.$sorder;
					break;
			}
		}
	}

	$orderby = ' ORDER BY ' . join(',', $orderby);

	// Do it
	assert_article();
	$rs = safe_rows('*, unix_timestamp(Posted) as uPosted, unix_timestamp(Expires) as uExpires, unix_timestamp(LastMod) as uLastMod',
	'textpattern',
	$statSQL.
		(($category) ? $catSQL : '').
		(($section) ? $secSQL : '').
		(($author) ? $authSQL : '').
		$timeSQL.
		$expired.
		$orderby,
	$debug);
	if ($debug > 1 && $rs) {
		echo '++ RECORD SET ++';
		dmp($rs);
	}
	// Find the current article in the record set, then move to find next/prev
	$last = $curr = $ctr = 1;

	foreach ($rs as $row) {
		if ($row['ID'] == $thisarticle['thisid']) {
			$curr = $last;
			break;
		}
		$last = $row; // Store current
		$ctr++;
	}

	if ($curr !== 1) {
		if ($dir=='next') {
			$smd_last['position'] = $ctr;
			$smd_last['section'] = $thisarticle['section'];
			$smd_last['psec'] = $pretext['s'];
			$smd_last['pcat'] = $pretext['c'];
			$smd_last['category1'] = $thisarticle['category1'];
			$smd_last['category2'] = $thisarticle['category2'];
			$smd_last['author'] = $thisarticle['authorid'];
		} else {
			$smd_first['position'] = $ctr;
			$smd_first['psec'] = $pretext['s'];
			$smd_first['pcat'] = $pretext['c'];
			$smd_first['section'] = $thisarticle['section'];
			$smd_first['category1'] = $thisarticle['category1'];
			$smd_first['category2'] = $thisarticle['category2'];
			$smd_first['author'] = $thisarticle['authorid'];
		}
	} else {
		if ($dir=='next') {
			$smd_last = array();
		} else {
			$smd_first = array();
		}
	}

	if ($debug) {
		if ($dir=='next') {
			echo '++ MOST RECENT (NEXT) ++';
			dmp($smd_last);
		} else {
			echo '++ MOST RECENT (PREV) ++';
			dmp($smd_first);
		}
	}

	// Populate globals if the next/prev article exists
	$out = '';
	$saved = array();
	if ($curr === 1) {
		$out = parse($thing);
	} else {
		// Keep a note of where we were
		article_push();
		$saved['prev_id'] = $prev_id;
		$saved['next_id'] = $next_id;
		$saved['prev_title'] = $prev_title;
		$saved['next_title'] = $next_title;

		// Pretend we're in the new article, and fake the global vars
		populateArticleData($curr);
		$prev_id = ($dir=='prev') ? $curr['ID'] : '';
		$next_id = ($dir=='next') ? $curr['ID'] : '';
		$prev_title = ($dir=='prev') ? $curr['Title'] : '';
		$next_title = ($dir=='next') ? $curr['Title'] : '';
		$url = permlinkurl_id($curr['ID']);
		$thing = (empty($thing)) ? '<a rel="'.$dir.'" href="'.$url.'" title="'.$curr['Title'].'">'.$curr['Title'].'</a>' : $thing;
		$out = parse($thing);

		// Restore everything
		$prev_id = $saved['prev_id'];
		$next_id = $saved['next_id'];
		$prev_title = $saved['prev_title'];
		$next_title = $saved['next_title'];
		article_pop();
	}
	$smd_in_nearest = false;
	return $out;
}

// ****************************
// Private function: not for public consumption
// ****************************
function smd_link_to($atts, $thing = NULL) {
	global $next_id, $prev_id, $next_title, $prev_title, $smd_last, $smd_first, $smd_in_nearest;

	extract(lAtts(array(
		'showalways' => 0,
		'wraptag' => '',
		'class' => '',
		'urlvars' => '',
		'dir' => 'next', // Set by wrapper tags
		'debug' => '0',
	), $atts));

	// Maintain any URL variables
	$addArgs = array();
	if($urlvars) {
		$optencode = $optforce = $optpri = false;
		if (strpos($urlvars, 'SMD_ALL') === 0) {
			// Determine if options are to be applied globally
			$urlopts = do_list($urlvars, ':');
			$optencode = (in_array('ESCAPE', $urlopts)) ? true : false;
			$optforce = (in_array('FORCE', $urlopts)) ? true : false;
			$optpri = (in_array('TAG_PRIORITY', $urlopts)) ? true : false;
			// POST overrides GET if both exist
			$urlvars = array_merge(array_keys($_GET), array_keys($_POST));
		} else {
			$urlvars = do_list($urlvars);
		}
		foreach ($urlvars as $urlvar) {
			$urlopts = do_list($urlvar, ':');
			$encode = ($optencode || in_array('ESCAPE', $urlopts)) ? true : false;
			$force = ($optforce || in_array('FORCE', $urlopts)) ? true : false;
			$pri = ($optpri || in_array('TAG_PRIORITY', $urlopts)) ? true : false;
			$urlparts = do_list($urlopts[0], '=');
			$var = $urlparts[0];
			$val = gps($urlparts[0]);
			if ($pri) {
				$val = (isset($urlparts[1])) ? $urlparts[1] : gps($urlparts[0]);
			} else {
				if ($val=='' && isset($urlparts[1])) {
					$val = $urlparts[1];
				}
			}
			$val = ($encode) ? htmlentities($val) : $val;
			if ($val !== '' || $force) {
				$addArgs[] = $var.'='.$val;
			}
		}
	}

	if ($debug && $addArgs) {
		echo '++ URL VARS ++';
		dmp($addArgs);
   }

	if ($dir=='next' && (($smd_in_nearest) ? $smd_last : 1)) {
		if ($next_id) {
			$url = permlinkurl_id($next_id) . (($addArgs) ? '?'. join(a, $addArgs) : '');
			if ($thing) {
				$thing = parse($thing);
				$next_title = escape_title($next_title);

				return doWrap(array('<a rel="next" href="'.$url.'"'. (($class && !$wraptag) ? ' class="'.$class.'"' : '').
					($next_title != $thing ? ' title="'.$next_title.'"' : '').
					'>'.$thing.'</a>'), $wraptag, '', $class);
			}
			return $url;
		} else {
			return ($showalways) ? parse($thing) : '';
		}
	}
	if ($dir=='prev' && (($smd_in_nearest) ? $smd_first : 1)) {
		if ($prev_id) {
			$url = permlinkurl_id($prev_id) . (($addArgs) ? '?'. join(a, $addArgs) : '');
			if ($thing) {
				$thing = parse($thing);
				$prev_title = escape_title($prev_title);

				return doWrap(array('<a rel="prev" href="'.$url.'"'. (($class && !$wraptag) ? ' class="'.$class.'"' : '').
					($prev_title != $thing ? ' title="'.$prev_title.'"' : '').
					'>'.$thing.'</a>'), $wraptag, '', $class);
			}
			return $url;
		} else {
			return ($showalways) ? parse($thing) : '';
		}
	}
	return;
}