import logging

def listServers(serverName):
    # Input validation
    if not type(serverName) is list:
        raise TypeError("listServers: serverName must be a list, '" + str(serverName) + "' is not.")
    # Check if the first item in the list is the header. If this is true (data started at right place), most likely the other data is fine as well.
    if not serverName[0] == 'Bay Server Name                                       Serial Number   Status   Power   UID Partner\r':
        logging.critical(serverName)
        raise ValueError('listServers: Unexpected data recieved.')

    serverNamePos = [] # Init list

    # https://stackoverflow.com/a/19842807
    haystack = serverName[1]
    needle = ' '
    for i, _ in enumerate(haystack):
        if haystack[i:i + len(needle)] == needle:
            serverNamePos.append(i) # Add results to list. The last positions of each field are indexed, the next one being the seperator.

    serverNameFields = len(serverNamePos) # How many fields do we have to process

    servers = [] # Init, the results of this.
    for srv in range(2, len(serverName)): # Loop through servers. | Adjust for the first two being headers.
        # Fields: [BayNumber "Server Name", "Serial Number", "Status", "Power", "UID Partner"]
        serverNameCurrentTmp = [] # Init

        for fld in range(serverNameFields):
            if fld == 0: # Special case, as i-1 would loop around.
                serverNameCurrentTmp.append( int( serverName[srv][0:serverNamePos[fld]].strip() ) ) # Also convert to int, as we know it's a number.
            else:
                serverNameCurrentTmp.append( serverName[srv][serverNamePos[fld-1]+1:serverNamePos[fld]].strip() ) # Get ith field by character position.
        if not ( serverNameCurrentTmp[1] == '[Absent]' and serverNameCurrentTmp[4] == '' ): # If name is Absent and power status isn't available, there probably isn't a server there.
            servers.append(serverNameCurrentTmp) # Only append if the bay is actually in use.

    logging.debug('Servers:')
    logging.debug(servers)
    #breakpoint()

    return(servers)

# Testing data:
#serverName = ['Bay Server Name                                       Serial Number   Status   Power   UID Partner\r', '--- ------------------------------------------------- --------------- -------- ------- --- -------\r', '  1 foo-lab-1                                                         OK       On      Off \r', '  2 foo-lab-2                                         CZ302243P9      OK       On      Off \r', '  3 foo-lab-3                                         CZJI441OKP      Failed   On      Off \r', '  4 kspve1                                            CZJ18450FK      OK       On      Off \r', '  5 kspve2-2                                                          OK       On      Off \r', '  6 kspve3                                                            OK       On      Off \r', '  7 foo-blade                                                       OK       On      Off \r', '  8 Bar-01                                         CZ241274CC      OK       On      Off \r', '  9 baz-sar                                      CZ3217FNYE      OK       On      Off \r', ' 10 baz-sar2                                     CZ3217FFSS      OK       On      Off \r', ' 11 [Absent]                                          \r', ' 12 bee-bar                                                     OK       On      Off \r', ' 13 [Absent]                                          \r', ' 14 [Absent]                                          \r', ' 15 [Absent]                                          \r', ' 16 [Absent]                                          \r']
#print(listServers(serverName))