import pvl.dhcp.config
import pvl.hosts.host

class HostDHCPError(pvl.hosts.host.HostError):
    pass

def dhcp_host_options (host, ethernet):
    """
        Yield specific dhcp.conf host { ... } parameters for build_block()
    """

    yield 'option', 'host-name', host.name
    yield 'hardware', 'ethernet', ethernet

    if host.ip:
        yield 'fixed-address', str(host.ip)
      
    if not host.boot:
        next_server = filename = None
    elif ':' in host.boot :
        next_server, filename = host.boot.split(':', 1)
    elif host.boot.startswith('/') :
        next_server = None
        filename = host.boot
    elif host.boot.endswith(':') :
        next_server = host.boot
        filename = None
    else :
        raise HostError(host, "invalid boot={host.boot}".format(host=host))

    if next_server:
        yield 'next-server', next_server
    
    if filename:
        yield 'filename', filename

def dhcp_host (host):
    """
        Yield (block, items, **opts) tuples for pvl.dhcp.config.build_block().
    """

    if set(host.ethernet) == set([None]) :
        host_fmt = "{host.name}"
    elif host.ethernet :
        host_fmt = "{host.name}-{index}"
    else :
        # nothing to be seen here
        return
 
    if host.owner :
        comment = u"Owner: {host.owner}".format(host=host)
    else:
        comment = None

    for index, ethernet in host.ethernet.iteritems() :
        name = host_fmt.format(host=host, index=index)

        yield ('host', name), list(dhcp_host_options(host, ethernet)), dict(comment=comment)
    
def apply_hosts_dhcp (options, hosts):
    """
        Generate dhcp.conf output lines for the set of hosts.

        Verifies that there are no dupliate hosts.
    """

    blocks = { }

    for host in hosts:
        for block, items, opts in dhcp_host(host):
            if block in blocks:
                raise HostDHCPError(host, "dupliate host block {block}: {other}".format(block=block, other=blocks[block]))

            blocks[block] = block

            for line in pvl.dhcp.config.build_block(block, items, **opts):
                yield line
            
            yield ''