From f07dbf7439e2c51cbad228e73be53cc6effa56b2 Mon Sep 17 00:00:00 2001
From: nathangray <nathangray.bsc+github@gmail.com>
Date: Fri, 2 Feb 2018 11:37:02 -0700
Subject: [PATCH] Attempt to prefer user's date format when parsing date from a
 string.

Should fix merging into spreadsheet problems with certain date formats (dd/mm/yyyy)
---
 api/src/DateTime.php      | 53 ++++++++++++++++++++++++++++++++++++++-
 api/src/Storage/Merge.php | 29 +--------------------
 2 files changed, 53 insertions(+), 29 deletions(-)

diff --git a/api/src/DateTime.php b/api/src/DateTime.php
index f327b2ad2f..7f2eaec8ba 100644
--- a/api/src/DateTime.php
+++ b/api/src/DateTime.php
@@ -467,7 +467,8 @@ class DateTime extends \DateTime
 		{
 			try
 			{
-				$time = new DateTime($time);
+				// Try user format first
+				$time = static::createFromUserFormat($time);
 			}
 			catch(\Exception $e)
 			{
@@ -478,6 +479,56 @@ class DateTime extends \DateTime
 		return $time->format($type);
 	}
 
+	/**
+	 * Some user formats are conflicting and cannot be reliably parsed by the
+	 * normal means.  Here we agressively try various date formats (based on
+	 * user's date preference) to coerce a troublesome date into a DateTime.
+	 *
+	 * ex: 07/08/2018 could be DD/MM/YYYY or MM/DD/YYYY
+	 *
+	 * Rather than trust DateTime to guess right based on its settings, we use
+	 * the user's date preference to resolve the ambiguity.
+	 *
+	 * @param string $time
+	 * @return DateTime or null
+	 */
+	public static function createFromUserFormat($time)
+	{
+		$date = null;
+
+		// If numeric, just let normal constructor do it
+		if(is_numeric($time))
+		{
+			return new DateTime($time);
+		}
+
+		// Various date formats in decreasing preference
+		$formats = array(
+			'!'.static::$user_dateformat . ' ' .static::$user_timeformat.':s',
+			'!'.static::$user_dateformat . '*' .static::$user_timeformat.':s',
+			'!'.static::$user_dateformat . '* ' .static::$user_timeformat,
+			'!'.static::$user_dateformat . '*',
+			'!'.static::$user_dateformat,
+			'!Y-m-d\TH:i:s'
+		);
+		// Try the different formats, stop when one works
+		foreach($formats as $f)
+		{
+			try {
+				$date = static::createFromFormat(
+					$f,
+					$time,
+					static::$user_timezone
+				);
+				if($date) break;
+			} catch (\Exception $e) {
+
+			}
+		}
+		// Need correct class, createFromFormat() gives parent
+		return new DateTime($date ? $date : $time);
+	}
+
 	/**
 	 * Setter for user timezone, should be called after reading user preferences
 	 *
diff --git a/api/src/Storage/Merge.php b/api/src/Storage/Merge.php
index 4be334770e..20f873b95d 100644
--- a/api/src/Storage/Merge.php
+++ b/api/src/Storage/Merge.php
@@ -1288,34 +1288,7 @@ abstract class Merge
 			$field = preg_quote($field, '/');
 			if($values[$key])
 			{
-				if(!is_numeric($values[$key]))
-				{
-					// Try the different formats, stop when one works
-					foreach($formats as $f)
-					{
-						try {
-							$date = Api\DateTime::createFromFormat(
-								$f,
-								$values[$key],
-								Api\DateTime::$user_timezone
-							);
-							if($date) break;
-						} catch (\Exception $e) {
-
-						}
-					}
-					if(!$date)
-					{
-						// Couldn't get a date out of it... skip it
-						trigger_error("Unable to parse date $key = '{$values[$key]}' - left as text", E_USER_NOTICE);
-						unset($names[$idx]);
-						continue;
-					}
-				}
-				else
-				{
-					$date = new Api\DateTime($values[$key]);
-				}
+				$date = Api\DateTime::createFromUserFormat($values[$key]);
 				if($mimetype == 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet' ||
 					$mimetype == 'application/vnd.ms-excel.sheet.macroenabled.12')//Excel WTF
 				{