%%%-------------------------------------------------------------------
%%% @author anlicheng
%%% @copyright (C) 2025, <COMPANY>
%%% @doc
%%%
%%% @end
%%% Created : 12. 11月 2025 17:08
%%%-------------------------------------------------------------------
-module(upload_channel).
-author("anlicheng").

%% API
-export([init/2]).

init(Req0, Opts) ->
    Method = binary_to_list(cowboy_req:method(Req0)),
    lager:debug("[upload_channel] method is: ~p", [Method]),

    Headers = cowboy_req:headers(Req0),
    lager:debug("headers is: ~p", [Headers]),
    case maps:find(<<"content-type">>, Headers) of
        {ok, <<"application/octet-stream">>} ->
            Filename = maps:get(<<"x-filename">>, Headers),
            case filename:extension(Filename) of
                <<>> ->
                    Req = cowboy_req:reply(400, #{
                        <<"Content-Type">> => <<"text/html;charset=utf-8">>
                    }, <<"Miss file extension">>, Req0),
                    {ok, Req, Opts};
                _ ->
                    Basename = filename:basename(Filename),
                    handle_raw_file(Req0, binary_to_list(Basename)),
                    Req2 = cowboy_req:reply(400, #{
                        <<"Content-Type">> => <<"text/html;charset=utf-8">>
                    }, <<"ok">>, Req0),
                    {ok, Req2, Opts}
            end;
        {ok, ContentType} ->
            lager:debug("[upload_channel] unexpect content-type: ~p", [ContentType]),
            Req = cowboy_req:reply(400, #{
                <<"Content-Type">> => <<"text/html;charset=utf-8">>
            }, <<"Expected application/octet-stream">>, Req0),
            {ok, Req, Opts};
        error ->
            Req = cowboy_req:reply(400, #{
                <<"Content-Type">> => <<"text/html;charset=utf-8">>
            }, <<"Miss content-type header">>, Req0),
            {ok, Req, Opts}
    end.

%% 读取请求体
handle_raw_file(Req, Basename) ->
    Filename = make_file(Basename),
    {ok, IoDevice} = file:open(Filename, [write]),
    ok = handle_raw_file0(Req, IoDevice),
    ok = file:close(IoDevice).

handle_raw_file0(Req, IoDevice) ->
    case cowboy_req:read_body(Req) of
        {ok, Data, Req1} ->
            file:write(IoDevice, Data),
            ok;
        {more, Data, Req1} ->
            file:write(IoDevice, Data),
            handle_raw_file0(Req1, IoDevice)
    end.

make_file(Basename) when is_list(Basename) ->
    {ok, UploadDir} = application:get_env(efka, upload_dir),
    {{Y, M, D}, _} = calendar:local_time(),
    DateDir = io_lib:format("~p-~p-~p", [Y, M, D]),
    BaseDir = UploadDir ++ DateDir,
    case filelib:is_dir(BaseDir) of
        true ->
            ok;
        false ->
            ok = file:make_dir(BaseDir)
    end,
    BaseDir ++ "/" ++ Basename.