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-module(dreki_urn).
-define(PT, dreki_urn).
-export([nid/0, start/0, namespaces/0, namespace/1, register_namespace/3, expand/1, to_urn/1]).
-callback expand_urn_resource_rest(namespace(), expanded_resource(), resource_part(), NsEnv :: #{}) -> {ok, expanded_resource()} | {error, any()}.
-type urn() :: binary().
-type namespace() :: binary().
-type directory() :: binary().
-type location_part() :: binary().
-type resource_part() :: binary().
nid() -> <<"dreki">>.
-spec start() -> ok.
start() ->
persistent_term:put(?PT, #{}).
-spec namespaces() -> #{namespace() := {module(), #{}}}.
namespaces() ->
persistent_term:get(?PT).
-spec namespace(namespace()) -> {module(), #{}} | undefined.
namespace(NS) ->
maps:get(NS, namespaces(), undefined).
-spec register_namespace(namespace(), module(), #{}) -> ok | {error, {namespace_already_registered, namespace(), module()}}.
register_namespace(Namespace, Mod, Env) ->
Map = persistent_term:get(?PT),
case maps:get(Namespace, Map, {Mod, undefined}) of
{Mod, Env} -> ok;
{Mod, _} -> persistent_term:put(?PT, maps:put(Namespace, {Mod, Env}, Map));
{OtherMod, _} -> {error, {namespace_already_registered, Namespace, OtherMod}}
end.
-type expand_error() :: not_dreki_urn.
-spec expand(urn()) -> {ok, expanded()} | {error, expand_error()}.
expand(U = <<"dreki:", _/binary>>) ->
expand(U, dreki_world:root_path());
expand(U = <<"urn:dreki:", _/binary>>) ->
expand(U, dreki_world:root_path());
expand(_Invalid) ->
{error, not_dreki_urn}.
%% Remove root
%%expand(U, Root) ->
%% expand(U, Root, Rest).
%%expand(U, Root) ->
%% {error, #{message => <<"URI outside of domain">>, uri => U, domain => Root}}.
%% Extract hierarchy
expand(U, Root) ->
{Hier, Res} = case binary:split(U, <<"::">>) of
[H, R] -> {H, R};
[H] -> {H, undefined}
end,
% XXX: Do we really need to store theses paths ? o_o
case dreki_world:get_path(Hier) of
{ok, Thing} -> expand(U, Root, Hier, Res, Thing);
Error -> Error
end.
-type expanded() :: #{
urn := urn(),
world := binary(),
location := location_part(),
kind := region | node | [],
resource => expanded_resource(),
query => #{},
fragment => binary()
}.
-type expanded_resource() :: #{
resource => expanded_resource_resource(),
directory => expanded_resource_directory(),
namespace => namespace(),
lookup => expanded_resource_lookup()
}.
-type expanded_resource_lookup() :: #{
namespace => namespace(),
id => binary()
}.
-type expanded_resource_resource() :: #{
namespace => namespace(),
directory => binary(),
id => binary()
}.
-type expanded_resource_directory() :: #{
namespace => namespace(),
directory => directory()
}.
expand(Urn, Root, Path, ResPart, Thing) ->
Kind = case maps:keys(Thing) of
[K] -> K;
Ks -> Ks
end,
XUrn = #{world => Root, kind => Kind, domain => Root, location => Path, urn => Urn},
case expand_resource(ResPart) of
{ok, Resource} ->
{ok, XUrn#{resource => Resource}};
{error, invalid_resource} ->
{error, #{message => <<"Invalid resource">>, uri => Urn, resource => ResPart}};
{error, invalid_namespace, NS} ->
{error, #{message => <<"Invalid namespace">>, uri => Urn, namespace => NS}}
end.
expand_resource(undefined) ->
{ok, undefined};
expand_resource(Path) ->
{NS, Rest} = case binary:split(Path, <<":">>) of
[N, R] -> {N, R};
[N] -> {N, <<>>}
end,
case namespace(NS) of
NSS = {_, _} -> expand_resource(NS, Rest, NSS);
undefined -> {error, invalid_namespace, NS}
end.
expand_resource(NS, FullResPart, {NSMod, NSEnv}) ->
{ResPart, Rest} = case binary:split(FullResPart, <<"::">>) of
[R] -> {R, undefined};
[R, Rs] -> {R, Rs}
end,
case expand_resource_part(NS, ResPart) of
Error = {error, _} -> Error;
{ok, Res} -> expand_resource_rest(NS, NSMod, NSEnv, Res, Rest)
end.
expand_resource_part(NS, ResPart) ->
case binary:split(ResPart, <<":">>, [global]) of
[<<>>, <<>>] -> {error, invalid_resource};
[<<>>, Id] -> {ok, #{lookup => #{namespace => NS, id => Id}}};
[<<>>] -> {ok, #{namespace => NS}};
[S] -> {ok, #{directory => #{namespace => NS, directory => S}}};
[S, <<>>] -> {ok, #{directory => #{namespace => NS, directory => S}}};
[S, Id] -> {ok, #{resource => #{namespace => NS, directory => S, id => Id}}};
[] -> {ok, #{namespace => NS}};
R -> {error, {invalid_address, {ResPart, R}}}
end.
expand_resource_rest(_, _, _, Resource, undefined) ->
{ok, Resource};
expand_resource_rest(NS, NSMod, NSEnv, Resource, Part) ->
case NSMod:expand_urn_resource_rest(NS, Resource, Part, NSEnv) of
{ok, Data} -> {ok, Data};
error -> {error, {invalid_part, {NS, Part}}}
end.
to_urn(XUrn = #{location := Location}) ->
case resource_to_urn_part(XUrn) of
Binary when is_binary(Binary) -> <<Location/binary, "::", Binary/binary>>;
undefined -> Location
end.
resource_to_urn_part(#{resource := Res0 = #{schemas := all}}) ->
Res = maps:remove(schemas, Res0),
ResP = resource_to_urn_part(Res),
<<ResP/binary, "::", "schemas">>;
resource_to_urn_part(#{resource := Res0 = #{schema := #{schema := Schema, version := Vers}}}) ->
Res = maps:remove(schema, Res0),
ResP = resource_to_urn_part(Res),
<<ResP/binary, "::", "schemas:", Schema/binary, ":", Vers/binary>>;
resource_to_urn_part(#{resource := #{namespace := NS}}) ->
NS;
resource_to_urn_part(#{resource := #{directory := #{directory := Dir, namespace := NS}}}) ->
<<NS/binary, ":", Dir/binary>>;
resource_to_urn_part(#{resource := #{resource := #{id := Id, directory := Dir, namespace := NS}}}) ->
<<NS/binary, ":", Dir/binary, ":", Id/binary>>.
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