% vim set ft=prolog

:- module(bgp, [
    warning/1,
    create_firewall/0,
    neighbor/2,
    bgp_config/2,
    bird_config/1,
    remote_network/2,
    remote_networks/2]).
:- use_module(hosts, [
    host/1,
    host_config/2,
    router_link/3,
    attached_network/2]).
:- use_module(firewall, [
    fw_rule/2,
    retract_all_from/1]).

%host(H) :- router_link(H, _, _).
%host(H) :- router_link(_, H, _).
% host(H).

router(R) :- host(R), hosts:host_config(R, _).
routers(Routers) :- setof(router(R), router(R), Routers).

neighbor(H, R) :-
    router(H), router(R),
    router_link(H, _, R),
    router_link(R, _, H).

warning(Msg) :-
    host(H), host(R),
    router_link(H, _, R),
    \+ router_link(R, _, H),
    format(string(Msg), "Missing router_link from '~w' to '~w'", [R, H]).

neighbors(H, Cs) :- findall(neighbor(H, Name), neighbor(H, Name), Cs).

bgp_config(H, Connections) :- neighbor(H, Connections).
% bgp_config(H)?

bird_protocol_bgp(Router, Neighbor, Address, AllowedNetworks) :-
  router_link(Router, _, Neighbor),
  router_link(Neighbor, Address, Router),
  AllowedNetworks = [].

% edge(a, b). edge(b, c). edge(c, d). edge(d, a).
% path(X, Y) :- edge(X, Y).
% path(X, Y) :- edge(X, Z), path(Z, Y).

attached_networks(Router, Ns) :-
  findall(N, attached_network(Router, N), Ns).

remote_network(Router, N) :-
  router_link(Router, _, Remote),
  attached_network(Remote, N).

remote_networks(Router, Ns) :-
  router_link(Router, _, Remote),
  attached_networks(Remote, Ns).

% doesn't recurse
% available_networks(R, Ns) :-
%   attached_networks(R, Attached),
%   setof(N, remote_network(R, N), Remote),
%   union(Attached, Remote, Xs),

router_path(X, Y) :- router_path(X, Y, []).
router_path(X, Y, _)    :- router_link(X, _, Y).
router_path(X, Y, V) :- \+ member(X, V), router_link(X, _, Z), router_path(Z, Y, [X|V]).

%to_yaml(neighbor(H, Remote), Dict) :- Dict = yaml(router(H), remote(Remote)).
%to_json(neighbor(H, Remote), Dict) :- Dict = json(router(H), remote(Remote)).

to_dict(router(R), Dict) :-
  neighbors(R, Neighbors),
  maplist(to_dict(), Neighbors, NeighborDicts),
  Dict = R-_{
    neighbors: NeighborDicts
  }.

to_dict(neighbor(_, Remote), Dict) :- host_config(Remote, RC),
  Dict = neighbor{
  neighbor:_{
    name: Remote,
    hostname: RC.ip
  }
}.

bird_config(BirdConfig) :-
  routers(Routers),
  maplist(to_dict(), Routers, RouterDicts),
  dict_pairs(BirdConfig, bird_config, RouterDicts).

create_firewall() :-
  firewall:retract_all_from(bgp),
  findall(fw(Host, Attrs), fw(Host, Attrs), Goals),
  maplist(assert_fw, Goals).

assert_fw(fw(Host, Attrs)) :-
  R = firewall:fw_rule(Host, Attrs.put(_{from:bgp})),
  writeln(R),
  assert(R).

fw(Host, attrs{src:Src, dst:Dst, family:ip6}) :-
  hosts:router_link(Host, _, Remote),
  hosts:host_config(Host, HostConfig),
  hosts:host_config(Remote, RemoteConfig),
  Src = RemoteConfig.ip,
  Dst = HostConfig.ip.