% vim set ft=prolog

% rule(src, dst, proto, port, source(..)).

:- module(firewall, [
    %fw_rule/2,
    warning/1,
    retract_all_from/1]).

:- use_module(library(assoc)).
:- use_module(library(csv)).
:- use_module(library(dcgs)).
:- use_module(library(files)).
:- use_module(library(format)).
:- use_module(library(lists)).
:- use_module(library(serialization/json)).

:- use_module(hosts, [
    router_link/3]).

:- dynamic(fw_rule/2).

warning(Msg) :-
    fw_rule(Host, Attr),
    \+ get_assoc("from", Attr, _),
    format("Missing 'from' on fw_rule for host '~w', ~w", [Host, Attr], Msg).

rules_from(From, Rules) :-
    findall(
        fw_rule(H, Attr),
        (
          fw_rule(H, Attr),
          get_assoc("from", Attr, From)
        ),
        Rules).

retract_all_from(From) :-
    rules_from(From, Rules),
    retract_rules(Rules).

retract_rules([R|Rules]) :- retract(R), retract_rules(Rules).
retract_rules([]).

ansible(Basedir) :-
    setof(Host, Attrs^fw_rule(Host, Attrs), Hosts),
    ansible_host(Basedir, Hosts).

ansible_host(Basedir, [Host|Hosts]) :-
    atom_chars(Host, HostS),
    append(Basedir, [HostS], DirPs),
    path_segments(Dir, DirPs),
    append(Basedir, [HostS, "firewall.csv"], FilePs),
    path_segments(File, FilePs),
    format("mkdir ~s~n", [Dir]),
    make_directory_path(Dir),
    ansible_firewall(File, Host),
    ansible_host(Basedir, Hosts).

get_opt(Key, Assoc, Value) :- (get_assoc(Key, Assoc, Value) -> true; Value='').

to_csv(Host, Attrs, Row) :- 
    get_opt(family, Attrs, Family),
    get_opt(src, Attrs, Src),
    get_opt(dst, Attrs, Dst),
    Row = [Host, Family, Src, Dst].

ansible_firewall(File, Host) :-
    format("ansible_firewall: ~s~n", [File]),
    findall(Attrs, fw_rule(Host, Attrs), Rules),
    maplist(to_csv(Host), Rules, Rows),
    write_csv(File, frame(['host','family','src','dst'], Rows)).