-module(ts_json).
-export([encode_record/1, record_to_ejson/1, ejson_to_record/2]).

-include("ts_db_records.hrl").

encode_record(Record) -> lists:flatten(json:encode(record_to_ejson(Record))).

record_to_ejson(Record=#ts_timeline{}) ->
    % pull out the timeline id
    {_Username, TimelineId} = Record#ts_timeline.ref,

    % create the EJSON struct
    {struct, [
        {id, atom_to_list(TimelineId)},
        {created, encode_datetime(Record#ts_timeline.created)},
        {description, Record#ts_timeline.desc}]}.

record_to_ejson(Record=#ts_entry{}) ->
    % pull out the entry id
    {_Username, _TimelineId, EntryId} = Record#ts_entry.ref,

    % convert the timestamp to a date-time
    DateTime = calendar:gregorian_seconds_to_datetime(Record#ts_entry.timestamp),

    % create the EJSON struct
    {struct, [
        {id, EntryId},
        {timestamp, encode_datetime(DateTime)},
        {mark, Record#ts_entry.mark},
        {notes, Record#ts_entry.notes}]}.

encode_datetime({{Year, Month, Day}, {Hour, Minute, Second}}) ->
    io_lib:format("~2B-~2B-~2BT~2.10.0B:~2.10.0B:~2.10.0BZ", 
        [Year, Month, Day, Hour, Minute, Second]).

ejson_to_record(Empty=#ts_timeline{}, EJSON) ->
    {struct, Fields} = EJSON,
    {Username, _} = Empty#ts_timeline.ref,

    #ts_timeline{
        ref = {Username, element(2, lists:keyfind(id, 1, EJSON))},
        created = decode_datetime(element(2, lists:keyfind(created, 1, EJSON))),
        desc = element(2, lists:keyfind(description, 1, EJSON))}.

ejson_to_record(Empty=#ts_entry{}, EJSON) ->
    {struct, Fields} = EJSON,
    {Username, TimelineId, _} = Empty#ts_entry.ref,

    #ts_entry{
        ref = {Username, TimelineId, element(2, lists:keyfind(id, 1, EJSON))},
        timestamp = calendar:datetime_to_gregorian_seconds(decode_datetime(
            element(2, lists:keyfind(timestamp, 1, EJSON)))),
        mark = element(2, lists:keyfind(mark, 1, EJSON)),
        notes = element(2, lists:keyfind(notes, 1, EJSON))}.

decode_datetime(DateTimeString) ->
    % TODO: catch badmatch and badarg on whole function

    [DateString, TimeString] = re:split(DateTimeString, "[TZ]",
        [{return, list}, trim]),

    [YearString, MonthString, DayString] =
        re:split(DateString, "-", [{return, list}]),

    [HourString, MinuteString, SecondString] =
        re:split(TimeString, ":", [{return, list}]),

    Date = {list_to_integer(YearString), list_to_integer(MonthString),
        list_to_integer(DayString)}

    Time = {list_to_integer(HourString), list_to_integer(MinuteString),
        list_to_integer(SecondString)}

    {Date, Time}.