Improve Integration With Payment Gateway and Membership Plugin

Hi, I need to integrate WP eMember using Post request and I am handling some issues. Here is how it is working now: Variables within post request: First name Last name Email Product ID Order status Relation between Product IDs and Membership Levels Product ID 1 = Membership Level 1 Product ID 2 = Membership Level 2 Product ID 3 = Membership Level 3 Logical: if status is “approved”, then check if the member username or email exists. If yes, do nothing. CREATE A MEMBERSHIP: If the username or email doesn’t exist, then add as new member, check the product ID and select the appropriate membership level. Username and password are randomly generated. UPDATE A MEMBERSHIP: If the username or email already exist, do nothing. There is no way to add a new membership level to the same member. DEACTIVATE A MEMBERSHIP: if status is “dispute” or “refunded”, then deactivate member (and consequently all membership levels). For example, if the member asks refund for product ID 3, membership levels 1, 2 and 3 are deactivated along with member. —————— How it was supposed to be: —————— Variables within post request: First name Last name Email Product ID Order status Relation between Product IDs and Membership Levels Product ID 1 = Membership Level 1 Product ID 2 = Membership Level 2 Product ID 3 = Membership Level 3 Logical: if status is “approved”, then check the product ID and match the appropriate membership level. Define username as email, and check if this username already exists. CREATE A MEMBERSHIP: If the username doesn’t exist, create a new member using the information available (First Name, Last Name, Email, Membership Level, Username and Password). Password is randomly defined. UPDATE A MEMBERSHIP: If the username already exists, check his current membership level(s). If the new membership level is already assigned for member, do nothing. If the new membership level is not assigned for member, then add the new membership level to the member’s account. So member will have 2 membership levels, and so on. DEACTIVATE A MEMBERSHIP: if status is “dispute” or “refunded”, then check the product ID and select the appropriate membership level. Then revoke access from that member to that specific membership level. I am attaching the php file that is currently handling post requests.