Regex Youtube - Set autoplay to 0 except for specific video hash - php

Question

I want to remove all references to autoplay in an URL - even multiple times if they exist - for all videos except the one (Uj1ykZWtPYI). The other settings URL parameters should remain.
Source:
<iframe src="//www.youtube.com/embed/1337?wmode=transparent&autoplay=1&controls=0&showinfo=0&modestbranding=1" frameborder="0" allowfullscreen=""></iframe>
Desired:
<iframe src="//www.youtube.com/embed/1337?wmode=transparent&controls=0&showinfo=0&modestbranding=1&autoplay=0" frameborder="0" allowfullscreen=""></iframe>
It appends autoplay=0 programmatically.
For the specified video (Uj1ykZWtPYI), it should behave like this:
Source:
<iframe src="//www.youtube.com/embed/Uj1ykZWtPYI?wmode=transparent&autoplay=0&controls=0&showinfo=0&modestbranding=1" frameborder="0" allowfullscreen=""></iframe>
Desired:
<iframe src="//www.youtube.com/embed/Uj1ykZWtPYI?wmode=transparent&controls=0&showinfo=0&modestbranding=1&autoplay=1" frameborder="0" allowfullscreen=""></iframe>`
It appends autoplay=1 programmatically.
What I've tried so far in PHP:
// Non-matching specific video
$content['message'] = preg_replace('/youtube.com\/embed\/([^Uj1ykZWtPYI]*)([^"&]*)/', 'youtube.com/embed/$1$2&autoplay=0', $content['message']);
// Result
// <iframe src="//www.youtube.com/embed/W6hr-o6JiWs?wmode=transparent&autoplay=1&autoplay=0" frameborder="0" allowfullscreen="">
// Matching specific video
$content['message'] = preg_replace('/youtube.com\/embed\/([Uj1ykZWtPYI]*)([^"&]*)/', 'youtube.com/embed/$1$2&autoplay=1', $content['message']);
// Result
// <iframe src="//www.youtube.com/embed/Uj1ykZWtPYI?wmode=transparent&autoplay=1&autoplay=0&controls=0&showinfo=0&modestbranding=1" frameborder="0" allowfullscreen=""></iframe>

Answer 1

Matching all links without Uj1ykZWtPYI
You can search for this regular expression to find all matches without Uj1ykZWtPYI in the URL:
\b(src="(?:(?!Uj1ykZWtPYI|").)+?)(?:&autoplay=(?:1|0))([^"]*?)"|\b(src="(?:(?!Uj1ykZWtPYI|"|&autoplay=(?:1|0)).)+?)"
Then, replace the it with this (autoplay is zero):
$1$2$3&autoplay=0"
Explanation:
\b(src="(?:(?!Uj1ykZWtPYI|").)+?)(?:&autoplay=(?:1|0))([^"]*?)": The first part of the pattern looks for any characters after src=", which are not equal an apostrophe [^"] or !Uj1ykZWtPYI and stops at autoplay. This forms the first group. The pattern has to have the characters &autoplay=1 or &autoplay=0 in it. After autoplay, everything except the " character is included into the second group - until ".
\b(src="(?:(?!Uj1ykZWtPYI|"|&autoplay=(?:1|0)).)+?)": The second part matches any url without an autoplay, a " and Uj1ykZWtPYI in it, but otherwise is the same as the first pattern.
If pattern 1 matches, the groups $1 and $2 form the valid URL without autosave. If it does not match, but the second one does, $3 will contain the full URL. So, $1$2$3 depicts in any of the two cases the full URL. &autoplay=0 is then added to the full URL afterwards.
This pattern only works, if autoplay is not the first argument (?autoplay).
Matching all links including the video code Uj1ykZWtPYI
If you want to match every link with Uj1ykZWtPYI in it to add autoplay=1 you can use a pretty similar pattern:
\b(src="[^"]*?Uj1ykZWtPYI[^"]*?)(?:&autoplay=(?:1|0))([^"]*?)"|\b(src="[^"]*?Uj1ykZWtPYI(?:(?!&autoplay=(?:1|0))[^"])+?)"
Then replace it with this (autoplay is one):
$1$2$3&autoplay=1"
Live Example
Here you can see both patterns in action (JavaScript) to replace your example string (all four example string combinations are added):
// 1337 as code, including autoplay
var string1 = '<iframe src="//www.youtube.com/embed/1337?wmode=transparent&autoplay=1&controls=0&showinfo=0&modestbranding=1" frameborder="0" allowfullscreen=""></iframe>';
// Uj1ykZWtPYI as code, including autoplay
var string2 = '<iframe src="//www.youtube.com/embed/Uj1ykZWtPYI?wmode=transparent&autoplay=1&controls=0&showinfo=0&modestbranding=1" frameborder="0" allowfullscreen=""></iframe>';
// 1337 as code, autoplay not included
var string3 = '<iframe src="//www.youtube.com/embed/1337?wmode=transparent&controls=0&showinfo=0&modestbranding=1" frameborder="0" allowfullscreen=""></iframe>';
// Uj1ykZWtPYIas code, autoplay not included
var string4 = '<iframe src="//www.youtube.com/embed/Uj1ykZWtPYI?wmode=transparent&controls=0&showinfo=0&modestbranding=1" frameborder="0" allowfullscreen=""></iframe>';
var regex1 = /\b(src="(?:(?!Uj1ykZWtPYI|").)+?)(?:&autoplay=(?:1|0))([^"]*?)"|\b(src="(?:(?!Uj1ykZWtPYI|"|&autoplay=(?:1|0)).)+?)"/g;
var regex2 = /\b(src="[^"]*?Uj1ykZWtPYI[^"]*?)(?:&autoplay=(?:1|0))([^"]*?)"|\b(src="[^"]*?Uj1ykZWtPYI(?:(?!&autoplay=(?:1|0))[^"])+?)"/g;
var replacement1 = '$1$2$3&autoplay=0"';
var replacement2 = '$1$2$3&autoplay=1"';
console.log(string1.replace(regex1, replacement1));
console.log(string2.replace(regex2, replacement2));
console.log(string3.replace(regex1, replacement1));
console.log(string4.replace(regex2, replacement2));