defmodule Naiveical.Helpers do
@moduledoc """
Some helper functions.
"""
@doc """
Splits a long line into several lines starting with a space.
"""
def unfold(ical_text) do
ical_text
|> String.replace(~r/\r?\n[ \t]/, "")
end
@doc """
https://www.rfc-editor.org/rfc/rfc5545#section-3.1:
Lines of text SHOULD NOT be longer than 75 octets, excluding the line
break. Long content lines SHOULD be split into a multiple line
representations using a line "folding" technique. That is, a long
line can be split between any two characters by inserting a CRLF
immediately followed by a single linear white-space character (i.e.,
SPACE or HTAB). Any sequence of CRLF followed immediately by a
single linear white-space character is ignored (i.e., removed) when
processing the content type.
The fold function splits a string across graphemes if the byte-size of the substring will
exceed the max_size. It then adds a CRLF and an empty space at the split-point.
"""
def fold(line, max_size \\ 75) do
# current_element = List.last(list)
# if byte_size(current_element + char) > max_size do
# end
# String.split("abc", "", parts: 2)
line
|> String.split("")
|> Enum.reduce([""], fn char, acc ->
[current_element | rest] = acc
if byte_size(current_element <> char) > max_size do
[" " <> char] ++ [current_element <> "\r\n"] ++ rest
else
[current_element <> char | rest]
end
end)
|> Enum.reverse()
|> Enum.join()
end
@doc """
Parse a timedate text into DateTime.
"""
def parse_datetime(datetime_str) do
datetime_format_str = "{YYYY}{0M}{0D}T{h24}{m}{s}Z"
naive_datetime_format_str = "{YYYY}{0M}{0D}T{h24}{m}{s}"
case Timex.parse(datetime_str, datetime_format_str) do
{:ok, datetime} ->
{:ok, DateTime.from_naive!(datetime, "Etc/UTC")}
_ ->
case Timex.parse(datetime_str, naive_datetime_format_str) do
{:ok, datetime} ->
{:ok, datetime}
_ ->
{:error, "could not parse #{datetime_str}"}
end
end
end
def parse_datetime!(datetime_str) do
case parse_datetime(datetime_str) do
{:ok, datetime} -> datetime
{:error, error} -> raise ArgumentError, error
end
end
def parse_datetime(datetime_str, timezone) do
if is_nil(timezone) or String.length(timezone) == 0 do
parse_datetime(datetime_str)
else
datetime_format_str = "{YYYY}{0M}{0D}T{h24}{m}{s}"
case Timex.parse(datetime_str, datetime_format_str) do
{:ok, datetime} -> DateTime.from_naive(datetime, timezone)
end
end
end
def parse_datetime!(datetime_str, timezone) do
case parse_datetime(datetime_str, timezone) do
{:ok, datetime} -> datetime
{:error, error} -> raise ArgumentError, error
end
end
@doc """
Parse a timedate text into DateTime.
"""
def parse_date!(date_str) do
date_format_str = "{YYYY}{0M}{0D}"
Timex.parse!(date_str, date_format_str)
end
def parse_date(date_str) do
date_str =
if String.contains?(date_str, "T") do
date_str
|> String.split("T")
|> List.first()
else
date_str
end
date_format_str = "{YYYY}{0M}{0D}"
case Timex.parse(date_str, date_format_str) do
{:ok, parsed_datetime} -> {:ok, NaiveDateTime.to_date(parsed_datetime)}
{:error, error} -> {:error, error}
end
end
def is_fullday(attributes, datetime_str) do
date_format_str = "{YYYY}{0M}{0D}"
if String.contains?(attributes, "VALUE=DATE") do
true
else
case Timex.parse(datetime_str, date_format_str) do
{:ok, datetime} -> true
_ -> false
end
end
end
end