%% @author Marc Worrell <marc@worrell.nl>
%% @copyright 2009 Marc Worrell <marc@worrell.nl>
%% Date: 2009-04-28
%% @doc Redirect to resources depening on the content type requested.

%% Copyright 2009 Marc Worrell
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%%     http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.

-module(controller_id).
-author("Marc Worrell <marc@worrell.nl>").

-export([
    resource_exists/1,
    previously_existed/1,
    moved_temporarily/1,
    content_types_provided/1,
    process/4,
    get_rsc_content_types/2
]).

-include_lib("zotonic_core/include/zotonic.hrl").

resource_exists(Context) ->
    {Id, ContextQs} = get_id(z_context:ensure_qs(Context)),
    z_context:lager_md(ContextQs),
    {m_rsc:exists(Id, ContextQs), ContextQs}.

previously_existed(Context) ->
    {Id, Context2} = get_id(Context),
    {m_rsc_gone:is_gone(Id, Context2), Context2}.

moved_temporarily(Context) ->
    {Id, Context2} = get_id(Context),
    redirect(m_rsc_gone:get_new_location(Id, Context2), Context2).

redirect(undefined, Context) ->
    {false, Context};
redirect(Location, Context) ->
    {{true, Location}, Context}.

content_types_provided(Context) ->
    {CTs, Context1} = get_content_types(Context),
    CTs1 = [ Mime || {Mime, _Dispatch} <- CTs],
    {CTs1, Context1}.

process(_Method, _AcceptedCT, ProvidedCT, Context) ->
    {CT, Context2} = get_content_types(Context),
    {Id, Context3} = get_id(Context2),
    Location = case proplists:get_value(ProvidedCT, CT) of
        page_url ->
            m_rsc:p_no_acl(Id, page_url, Context3);
        {url, Url} ->
            Url;
        {Dispatch, DispatchArgs} when is_atom(Dispatch), is_list(DispatchArgs) ->
            z_dispatcher:url_for(Dispatch, [{id,Id} | DispatchArgs], Context3);
        Dispatch when is_atom(Dispatch) ->
            z_dispatcher:url_for(Dispatch, [{id,Id}], Context3)
    end,
    AbsUrl = z_context:abs_url(Location, Context3),
    Context4 = z_context:set_resp_header(<<"location">>, AbsUrl, Context3),
    Context5 = z_context:set_resource_headers(Id, Context4),
    {{halt, 303}, Context5}.

%% @doc Fetch the list of content types provided, together with their dispatch rule name.
%% text/html is moved to the front of the list as that is the default mime type to be returned.
-spec get_rsc_content_types(m_rsc:resource(), z:context()) -> list().
get_rsc_content_types(Id, Context) ->
    z_notifier:foldr(#content_types_dispatch{id = Id}, [], Context).

get_content_types(Context) ->
    case z_context:get(content_types_dispatch, Context) of
        undefined ->
            {Id, Context1} = get_id(Context),
            CTs = get_rsc_content_types(Id, Context),
            CTs1 = case find_html(CTs) of
                    undefined -> [ {{<<"text">>, <<"html">>, []}, page_url} | CTs ];
                    Prov -> [ Prov | CTs ]
                  end,
            Context2 = z_context:set(content_types_dispatch, CTs1, Context1),
            {CTs1, Context2};
        CTs ->
            {CTs, Context}
    end.

find_html([]) ->
    undefined;
find_html([ {{<<"text">>, <<"html">>, _}, _} = Prov | _CTs ]) ->
    Prov;
find_html([ _ | CTs ]) ->
    find_html(CTs).

get_id(Context) ->
    case z_context:get(id, Context) of
        undefined ->
            case z_context:get_q(<<"id">>, Context) of
                undefined ->
                    {undefined, Context};
                <<>> ->
                    {undefined, Context};
                Id ->
                    RscId = m_rsc:rid(Id, Context),
                    {RscId, z_context:set(id, {ok, RscId}, Context)}
            end;
        {ok, Id} ->
            {Id, Context}
    end.