defmodule Tempus.Slot do
@moduledoc """
Declares a timeslot and exports functions to check whether the given date
and/or datetime is covered by this slot or not.
This module probably should not be called directly.
"""
alias __MODULE__
@typedoc "A timeslot to be used in `Tempus`"
@type t :: %__MODULE__{
from: nil | DateTime.t(),
to: nil | DateTime.t()
}
@typedoc "The origin used in comparisons and calculations"
@type origin :: Slot.t() | Date.t() | DateTime.t() | Time.t() | nil
defstruct [:from, :to]
@spec valid?(slot :: Slot.t()) :: boolean()
@doc """
Checks whether the `Slot` is valid (to > from) or not.
## Examples
iex> slot = %Tempus.Slot{from: ~U|2015-09-30 00:00:00Z|, to: ~U|2015-10-01 01:00:00Z|}
iex> Tempus.Slot.valid?(slot)
true
iex> Tempus.Slot.valid?(%Tempus.Slot{from: slot.to, to: slot.from})
false
"""
def valid?(%Slot{from: nil, to: %DateTime{}}), do: true
def valid?(%Slot{from: %DateTime{}, to: nil}), do: true
def valid?(%Slot{from: %DateTime{} = from, to: %DateTime{} = to}),
do: DateTime.compare(from, to) != :gt
def valid?(_), do: false
@spec cover?(slot :: Slot.t(), dt :: origin(), strict? :: boolean()) ::
boolean()
@doc """
Checks whether to `Slot` covers the data/datetime passed as a second argument.
## Examples
iex> dt_between = ~U|2015-09-30 01:00:00Z|
...> dt_from = ~U|2015-09-30 00:00:00Z|
...> dt_to = ~U|2015-10-01 01:00:00Z|
...> d_from = Date.from_iso8601!("2015-09-30")
...> d_to = Date.from_iso8601!("2015-10-01")
iex> slot = %Tempus.Slot{from: dt_from, to: dt_to}
iex> Tempus.Slot.cover?(slot, dt_between)
true
iex> Tempus.Slot.cover?(slot, dt_to)
true
iex> Tempus.Slot.cover?(slot, dt_to, true)
false
iex> Tempus.Slot.cover?(slot, d_from)
true
iex> Tempus.Slot.cover?(slot, d_from, true)
false
iex> Tempus.Slot.cover?(slot, d_to)
false
"""
def cover?(slot, dt, strict? \\ false)
def cover?(%Slot{from: nil, to: %DateTime{} = to}, %DateTime{} = dt, true),
do: DateTime.compare(to, dt) == :gt
def cover?(%Slot{from: %DateTime{} = from, to: nil}, %DateTime{} = dt, true),
do: DateTime.compare(from, dt) == :lt
def cover?(%Slot{from: %DateTime{} = from, to: %DateTime{} = to}, %DateTime{} = dt, true),
do: DateTime.compare(from, dt) == :lt and DateTime.compare(to, dt) == :gt
def cover?(%Slot{from: from, to: to} = slot, %DateTime{} = dt, false),
do:
cover?(slot, dt, true) or
(not is_nil(from) and DateTime.compare(from, dt) == :eq) or
(not is_nil(to) and DateTime.compare(to, dt) == :eq)
def cover?(%Slot{} = slot, %Date{} = dt, strict?),
do: cover?(slot, wrap(dt, slot.from || slot.to), strict?)
def cover?(%Slot{} = slot, %Time{} = dt, strict?),
do: cover?(slot, wrap(dt, slot.from || slot.to), strict?)
def cover?(%Slot{from: nil, to: %DateTime{}}, %Slot{from: nil, to: %DateTime{}}, true),
do: false
def cover?(
%Slot{from: nil, to: %DateTime{} = s_to},
%Slot{from: nil, to: %DateTime{} = dt_to},
false
),
do: DateTime.compare(s_to, dt_to) in [:lt, :eq]
def cover?(%Slot{from: %DateTime{}, to: nil}, %Slot{from: %DateTime{}, to: nil}, true),
do: false
def cover?(
%Slot{from: %DateTime{} = s_from, to: nil},
%Slot{from: %DateTime{} = dt_from, to: nil},
false
),
do: DateTime.compare(s_from, dt_from) in [:gt, :eq]
def cover?(%Slot{} = slot, %Slot{from: from, to: to}, strict?),
do: cover?(slot, from, strict?) and cover?(slot, to, strict?)
@spec disjoint?(s1 :: origin(), s2 :: origin()) :: boolean()
@doc """
Returns `true` if two slots are disjoined, `false` otherwise.
## Examples
iex> slot = %Tempus.Slot{from: ~U|2015-09-01 00:00:00Z|, to: ~U|2015-10-01 00:00:00Z|}
iex> inner = %Tempus.Slot{from: ~U|2015-09-01 00:00:00Z|, to: ~U|2015-09-01 01:00:00Z|}
iex> Tempus.Slot.disjoint?(slot, inner)
false
iex> inner = %Tempus.Slot{from: ~U|2015-09-01 00:00:00Z|, to: ~U|2015-10-01 01:00:00Z|}
iex> Tempus.Slot.disjoint?(slot, inner)
false
iex> outer = %Tempus.Slot{from: ~U|2015-10-01 00:00:01Z|, to: ~U|2015-10-01 01:00:00Z|}
iex> Tempus.Slot.disjoint?(slot, outer)
true
"""
def disjoint?(s1, s2) do
[%Slot{} = s1, %Slot{} = s2] = Enum.map([s1, s2], &wrap/1)
compare(s1, s2) in [:lt, :gt]
end
@spec intersect(slots :: Enum.t()) :: Slot.t() | nil
@doc """
Intersects slots to the minimal covered timeslice.
### Example
iex> Tempus.Slot.intersect([Tempus.Slot.wrap(~D|2020-09-30|),
...> %Tempus.Slot{from: ~U|2020-09-30 23:00:00Z|, to: ~U|2020-10-02 00:00:00Z|}])
#Slot<[from: ~U[2020-09-30 23:00:00Z], to: ~U[2020-09-30 23:59:59.999999Z]]>
"""
def intersect(slots) do
Enum.reduce(slots, fn
_slot, nil ->
nil
slot, acc ->
slot = wrap(slot)
if disjoint?(acc, slot),
do: nil,
else: %Slot{from: intersect_from(slot, acc), to: intersect_to(slot, acc)}
end)
end
@spec intersect_from(Slot.t(), Slot.t()) :: DateTime.t() | nil
defp intersect_from(%Slot{from: nil}, %Slot{from: nil}), do: nil
defp intersect_from(%Slot{from: f1}, %Slot{from: nil}), do: f1
defp intersect_from(%Slot{from: nil}, %Slot{from: f2}), do: f2
defp intersect_from(%Slot{from: f1}, %Slot{from: f2}), do: Enum.max([f1, f2], DateTime)
@spec intersect_to(Slot.t(), Slot.t()) :: DateTime.t() | nil
defp intersect_to(%Slot{to: nil}, %Slot{to: nil}), do: nil
defp intersect_to(%Slot{to: t1}, %Slot{to: nil}), do: t1
defp intersect_to(%Slot{to: nil}, %Slot{to: t2}), do: t2
defp intersect_to(%Slot{to: t1}, %Slot{to: t2}), do: Enum.min([t1, t2], DateTime)
@spec join(slots :: Enum.t()) :: Slot.t()
@doc """
Joins slots to the maximal covered timeslice.
### Example
iex> Tempus.Slot.join([Tempus.Slot.wrap(~D|2020-09-30|), Tempus.Slot.wrap(~D|2020-10-02|)])
#Slot<[from: ~U[2020-09-30 00:00:00.000000Z], to: ~U[2020-10-02 23:59:59.999999Z]]>
iex> Tempus.Slot.join([~D|2020-09-30|, ~D|2020-10-02|])
#Slot<[from: ~U[2020-09-30 00:00:00.000000Z], to: ~U[2020-10-02 23:59:59.999999Z]]>
"""
def join([]), do: %Slot{from: nil, to: nil}
def join([slot | slots]) do
Enum.reduce(slots, wrap(slot), fn slot, acc ->
slot = wrap(slot)
from =
if DateTime.compare(slot.from, acc.from) == :lt,
do: slot.from,
else: acc.from
to =
if DateTime.compare(slot.to, acc.to) == :gt,
do: slot.to,
else: acc.to
%Slot{from: from, to: to}
end)
end
@spec duration(slot :: Slot.t(), unit :: System.time_unit()) :: non_neg_integer() | :infinity
@doc """
Calculates the duration of a slot in units given as a second parameter
(default: `:second`.)
### Example
iex> ~D|2020-09-03| |> Tempus.Slot.wrap() |> Tempus.Slot.duration()
86400
"""
def duration(slot, unit \\ :second)
def duration(%Slot{from: nil, to: %DateTime{}}, _), do: :infinity
def duration(%Slot{from: %DateTime{}, to: nil}, _), do: :infinity
def duration(%Slot{from: %DateTime{} = from, to: %DateTime{} = to}, unit),
do: to |> DateTime.add(1, unit) |> DateTime.diff(from, unit)
@spec compare(s1 :: t(), s2 :: t(), strict :: boolean()) :: :lt | :gt | :eq | :joint
@doc """
Compares two slot structs.
Returns `:gt` if first slot is strictly later than the second and `:lt` for vice versa.
**NB** `:eq` is returned not only if slots are equal, but also when they are overlapped.
Might be used in `Enum.sort/2`.
"""
def compare(s1, s2, strict \\ false)
def compare(%Slot{from: nil, to: %DateTime{}}, %Slot{from: nil, to: %DateTime{}}, false),
do: :eq
def compare(
%Slot{from: nil, to: %DateTime{} = t1},
%Slot{from: nil, to: %DateTime{} = t2},
true
),
do: if(DateTime.compare(t1, t2) == :eq, do: :eq, else: :joint)
def compare(%Slot{from: %DateTime{}, to: nil}, %Slot{from: %DateTime{}, to: nil}, false),
do: :eq
def compare(
%Slot{from: %DateTime{} = f1, to: nil},
%Slot{from: %DateTime{} = f2, to: nil},
true
),
do: if(DateTime.compare(f1, f2) == :eq, do: :eq, else: :joint)
def compare(%Slot{from: f1, to: t1}, %Slot{from: f2, to: t2}, strict) do
f2l = t1 && f2 && DateTime.compare(t1, f2)
l2f = f1 && t2 && DateTime.compare(f1, t2)
case {strict, f2l, l2f} do
{_, :lt, _} ->
:lt
{_, _, :gt} ->
:gt
{false, _, _} ->
:eq
{true, nil, _} ->
:joint
{true, _, nil} ->
:joint
{true, _, _} ->
if DateTime.compare(f1, f2) == :eq && DateTime.compare(t1, t2) == :eq,
do: :eq,
else: :joint
end
end
@spec strict_compare(s1 :: Slot.t(), s2 :: Slot.t()) :: :eq | :lt | :gt | :joint
@doc """
Compares two slot structs. The same as `compare/2`, but returns `:joint` if
the slots are overlapped.
"""
def strict_compare(%Slot{} = s1, %Slot{} = s2),
do: compare(s1, s2, true)
@spec wrap(origin(), DateTime.t()) :: Slot.t()
@doc """
Wraps the argument into a slot. For `DateTime` it’d be a single microsecond.
For a `Date`, it would be the whole day, starting at `00:00:00.000000` and
ending at `23:59:59:999999`.
## Examples
iex> Tempus.Slot.wrap(~D|2020-08-06|)
#Slot<[from: ~U[2020-08-06 00:00:00.000000Z], to: ~U[2020-08-06 23:59:59.999999Z]]>
"""
def wrap(moment \\ nil, origin \\ DateTime.utc_now())
def wrap(nil, origin), do: wrap(DateTime.utc_now(), origin)
def wrap(%Slot{} = slot, _), do: slot
def wrap(%DateTime{} = dt, _), do: %Slot{from: dt, to: dt}
def wrap(
%Time{
calendar: calendar,
hour: hour,
microsecond: microsecond,
minute: minute,
second: second
},
origin
) do
wrap(%DateTime{
calendar: calendar,
day: origin.day,
hour: hour,
microsecond: microsecond,
minute: minute,
month: origin.month,
second: second,
std_offset: origin.std_offset,
time_zone: origin.time_zone,
utc_offset: origin.utc_offset,
year: origin.year,
zone_abbr: origin.zone_abbr
})
end
def wrap(%Date{calendar: calendar, day: day, month: month, year: year}, origin) do
%Slot{
from: %DateTime{
calendar: calendar,
day: day,
hour: 0,
microsecond: {0, 6},
minute: 0,
month: month,
second: 0,
std_offset: origin.std_offset,
time_zone: origin.time_zone,
utc_offset: origin.utc_offset,
year: year,
zone_abbr: origin.zone_abbr
},
to: %DateTime{
calendar: calendar,
day: day,
hour: 23,
microsecond: {999_999, 6},
minute: 59,
month: month,
second: 59,
std_offset: origin.std_offset,
time_zone: origin.time_zone,
utc_offset: origin.utc_offset,
year: year,
zone_abbr: origin.zone_abbr
}
}
end
@doc false
@spec shift(
slot :: t(),
action :: [{:to, integer()} | {:from, integer} | {:unit, System.time_unit()}]
) :: Slot.t()
def shift(%Slot{from: from, to: to}, action \\ []) do
unit = Keyword.get(action, :unit, :microsecond)
from = do_shift(from, Keyword.get(action, :from, 0), unit)
to = do_shift(to, Keyword.get(action, :to, 0), unit)
%Slot{from: from, to: to}
end
@spec do_shift(maybe_datetime, integer(), System.time_unit()) :: maybe_datetime
when maybe_datetime: nil | DateTime.t()
defp do_shift(nil, _, _), do: nil
defp do_shift(%DateTime{microsecond: {_, 0}} = dt, count, unit),
do:
%DateTime{dt | microsecond: {0, 6}}
|> DateTime.truncate(unit)
|> DateTime.add(count, unit)
defp do_shift(%DateTime{microsecond: {value, n}} = dt, count, unit),
do:
%DateTime{dt | microsecond: {:erlang.rem(value, round(:math.pow(10, n))), Enum.max([6, 6])}}
|> DateTime.truncate(unit)
|> DateTime.add(count, unit)
@spec shift_tz(
slot :: Slot.t(),
tz :: Calendar.time_zone(),
tz_db :: Calendar.time_zone_database()
) :: Slot.t()
@doc """
Shifts both `from` and `to` values to `UTC` zone.
### Examples
```elixir
slot = %Tempus.Slot{
from: DateTime.from_naive!(~N|2018-01-05 21:00:00|, "America/New_York"),
to: DateTime.from_naive!(~N|2018-01-08 08:59:59|, "Australia/Sydney")
}
#⇒ #Slot<[from: ~U[2018-01-06 02:00:00Z], to: ~U[2018-01-07 21:59:59Z]]>
```
"""
def shift_tz(
%Slot{from: from, to: to},
tz \\ "Etc/UTC",
tz_db \\ Calendar.get_time_zone_database()
) do
%Slot{from: DateTime.shift_zone!(from, tz, tz_db), to: DateTime.shift_zone!(to, tz, tz_db)}
end
defimpl Inspect do
import Inspect.Algebra
@fancy_inspect Application.compile_env(:tempus, :fancy_inspect, false)
def inspect(%Tempus.Slot{from: from, to: to}, %Inspect.Opts{custom_options: [_ | _]} = opts) do
opts.custom_options
|> Keyword.get(:fancy, @fancy_inspect)
|> case do
truthy when truthy in [:emoji, true] ->
value =
[from, to]
|> Enum.map(&DateTime.to_iso8601/1)
|> Enum.join(" → ")
tag =
case truthy do
:emoji -> "⌚"
true -> "#Slot"
end
concat([tag, "<", value, ">"])
_ ->
concat(["#Slot<", to_doc([from: from, to: to], opts), ">"])
end
end
def inspect(%Tempus.Slot{from: from, to: to}, opts) do
concat(["#Slot<", to_doc([from: from, to: to], opts), ">"])
end
end
end
