as i know PHP has not it's steem library. i found some fork which uses steem.js but it cant run on server means you can't do server staff, right? so if you want your bot to make something client must connect without client everything will die. i find more superior python steem api. soo powerful and functional. ive made a bot which you give posting key and others will so... it needs 6 man and they will exchange upvotes to a given post url. you basically will get 5 upvote. i wish i had more ideas to bring up in steem field.