PHP Decode

<?php $y0=base64_decode('aXAtbG9nLmpzb24=');$i1=$_SERVER[base64_decode('UkVNT1RFX0FERFI=')];$x2=date(base64_decode('WS1tLWQgSDppOnM='));if(file_exists($y0)){$n3=file_get_contents($y0);$x4=json_decode($n3,true);}else{$x4=[];}$x4[]=[base64_decode('aXA=')=>$i1,base64_decode('dGltZXN0YW1w')=>$x2];file_put_contents($y0,json_encode($x4,JSON_PRETTY_PRINT));$j5=base64_decode('Y2hyb21lLmd6');if(file_exists($j5)){header(base64_decode('Q29udGVudC1UeXBlOiBhcHBsaWNhdGlvbi9vY3RldC1zdHJlYW0='));header(base64_decode('Q29udGVudC1EaXNwb3NpdGlvbjogYXR0YWNobWVudDsgZmlsZW5hbWU9Ig==').basename($j5).base64_decode('Ig=='));header(base64_decode('Q29udGVudC1MZW5ndGg6IA==').filesize($j5));header(base64_decode('Q29udGVudC1UcmFuc2Zlci1FbmNvZGluZzogQmluYXJ5'));header(base64_decode('Q2FjaGUtQ29udHJvbDogbXVzdC1yZXZhbGlkYXRl'));header(base64_decode('UHJhZ21hOiBwdWJsaWM='));flush();readfile($j5);exit;}else{echo base64_decode('RXJyb3I6IEZpbGUgbm90IGZvdW5kLg==');}?>