This function extracts parameter data from a key in an iCalendar string.

iex> ICalendar.Decoder.retrieve_params(
...>   "DTSTART;TZID=America/Chicago")
["DTSTART", %{tzid: "America/Chicago"}]

It should be able to handle multiple parameters per key:

iex> ICalendar.Decoder.retrieve_params(
...>   "KEY;LOREM=ipsum;DOLOR=sit")
["KEY", %{lorem: "ipsum", dolor: "sit"}]

This function is designed to parse iCal datetime strings into erlang dates.

It should be able to handle dates from the past:

iex> {:ok, date} = ICalendar.Decoder.to_datetime("19930407T153022Z")
...> Timex.to_erl(date)
{{1993, 4, 7}, {15, 30, 22}}

As well as the future:

iex> {:ok, date} = ICalendar.Decoder.to_datetime("39930407T153022Z")
...> Timex.to_erl(date)
{{3993, 4, 7}, {15, 30, 22}}

And should return error for incorrect dates:

iex> ICalendar.Decoder.to_datetime("1993/04/07")
{:error, :invalid_format}

It should handle timezones from the Olson Database:

iex> {:ok, date} = ICalendar.Decoder.to_datetime("19980119T020000",
...> %{tzid: "America/Chicago"})
...> [Timex.to_erl(date), date.time_zone]
[{{1998, 1, 19}, {2, 0, 0}}, "America/Chicago"]

This function should strip any sanitization that has been applied to content within an iCal string.

iex> ICalendar.Decoder.unescape(~s(lorem\\, ipsum))
"lorem, ipsum"