{-# LANGUAGE Safe #-}

-- | Week-based calendars
module Data.Time.Calendar.WeekDate
    (
        Year, WeekOfYear, DayOfWeek(..), dayOfWeek,
        FirstWeekType (..),toWeekCalendar,fromWeekCalendar,fromWeekCalendarValid,
        -- * ISO 8601 Week Date format
        toWeekDate, fromWeekDate, pattern YearWeekDay,
        fromWeekDateValid, showWeekDate
    ) where

import Data.Time.Calendar.Types
import Data.Time.Calendar.Days
import Data.Time.Calendar.Week
import Data.Time.Calendar.OrdinalDate
import Data.Time.Calendar.Private


data FirstWeekType
    = FirstWholeWeek
    -- ^ first week is the first whole week of the year
    | FirstMostWeek
    -- ^ first week is the first week with four days in the year
    deriving FirstWeekType -> FirstWeekType -> Bool
(FirstWeekType -> FirstWeekType -> Bool)
-> (FirstWeekType -> FirstWeekType -> Bool) -> Eq FirstWeekType
forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
/= :: FirstWeekType -> FirstWeekType -> Bool
$c/= :: FirstWeekType -> FirstWeekType -> Bool
== :: FirstWeekType -> FirstWeekType -> Bool
$c== :: FirstWeekType -> FirstWeekType -> Bool
Eq

firstDayOfWeekCalendar :: FirstWeekType -> DayOfWeek -> Year -> Day
firstDayOfWeekCalendar :: FirstWeekType -> DayOfWeek -> Integer -> Day
firstDayOfWeekCalendar FirstWeekType
wt DayOfWeek
dow Integer
year = let
    jan1st :: Day
jan1st = Integer -> WeekOfYear -> Day
fromOrdinalDate Integer
year WeekOfYear
1
    in case FirstWeekType
wt of
        FirstWeekType
FirstWholeWeek -> DayOfWeek -> Day -> Day
firstDayOfWeekOnAfter DayOfWeek
dow Day
jan1st
        FirstWeekType
FirstMostWeek -> DayOfWeek -> Day -> Day
firstDayOfWeekOnAfter DayOfWeek
dow (Day -> Day) -> Day -> Day
forall a b. (a -> b) -> a -> b
$ Integer -> Day -> Day
addDays (-Integer
3) Day
jan1st

-- | Convert to the given kind of "week calendar".
-- Note that the year number matches the weeks, and so is not always the same as the Gregorian year number.
toWeekCalendar ::
    FirstWeekType
    -- ^ how to reckon the first week of the year
    -> DayOfWeek
    -- ^ the first day of each week
    -> Day
    -> (Year, WeekOfYear, DayOfWeek)
toWeekCalendar :: FirstWeekType
-> DayOfWeek -> Day -> (Integer, WeekOfYear, DayOfWeek)
toWeekCalendar FirstWeekType
wt DayOfWeek
ws Day
d = let
    dw :: DayOfWeek
dw = Day -> DayOfWeek
dayOfWeek Day
d
    (Integer
y0,WeekOfYear
_) = Day -> (Integer, WeekOfYear)
toOrdinalDate Day
d
    j1p :: Day
j1p = FirstWeekType -> DayOfWeek -> Integer -> Day
firstDayOfWeekCalendar FirstWeekType
wt DayOfWeek
ws (Integer -> Day) -> Integer -> Day
forall a b. (a -> b) -> a -> b
$ Integer -> Integer
forall a. Enum a => a -> a
pred Integer
y0
    j1 :: Day
j1 = FirstWeekType -> DayOfWeek -> Integer -> Day
firstDayOfWeekCalendar FirstWeekType
wt DayOfWeek
ws Integer
y0
    j1s :: Day
j1s = FirstWeekType -> DayOfWeek -> Integer -> Day
firstDayOfWeekCalendar FirstWeekType
wt DayOfWeek
ws (Integer -> Day) -> Integer -> Day
forall a b. (a -> b) -> a -> b
$ Integer -> Integer
forall a. Enum a => a -> a
succ Integer
y0
    in if Day
d Day -> Day -> Bool
forall a. Ord a => a -> a -> Bool
< Day
j1
        then (Integer -> Integer
forall a. Enum a => a -> a
pred Integer
y0,WeekOfYear -> WeekOfYear
forall a. Enum a => a -> a
succ (WeekOfYear -> WeekOfYear) -> WeekOfYear -> WeekOfYear
forall a b. (a -> b) -> a -> b
$ WeekOfYear -> WeekOfYear -> WeekOfYear
forall a. Integral a => a -> a -> a
div (Integer -> WeekOfYear
forall a. Num a => Integer -> a
fromInteger (Integer -> WeekOfYear) -> Integer -> WeekOfYear
forall a b. (a -> b) -> a -> b
$ Day -> Day -> Integer
diffDays Day
d Day
j1p) WeekOfYear
7,DayOfWeek
dw)
        else if Day
d Day -> Day -> Bool
forall a. Ord a => a -> a -> Bool
< Day
j1s then (Integer
y0,WeekOfYear -> WeekOfYear
forall a. Enum a => a -> a
succ (WeekOfYear -> WeekOfYear) -> WeekOfYear -> WeekOfYear
forall a b. (a -> b) -> a -> b
$ WeekOfYear -> WeekOfYear -> WeekOfYear
forall a. Integral a => a -> a -> a
div (Integer -> WeekOfYear
forall a. Num a => Integer -> a
fromInteger (Integer -> WeekOfYear) -> Integer -> WeekOfYear
forall a b. (a -> b) -> a -> b
$ Day -> Day -> Integer
diffDays Day
d Day
j1) WeekOfYear
7,DayOfWeek
dw)
        else (Integer -> Integer
forall a. Enum a => a -> a
succ Integer
y0,WeekOfYear -> WeekOfYear
forall a. Enum a => a -> a
succ (WeekOfYear -> WeekOfYear) -> WeekOfYear -> WeekOfYear
forall a b. (a -> b) -> a -> b
$ WeekOfYear -> WeekOfYear -> WeekOfYear
forall a. Integral a => a -> a -> a
div (Integer -> WeekOfYear
forall a. Num a => Integer -> a
fromInteger (Integer -> WeekOfYear) -> Integer -> WeekOfYear
forall a b. (a -> b) -> a -> b
$ Day -> Day -> Integer
diffDays Day
d Day
j1s) WeekOfYear
7,DayOfWeek
dw)

-- | Convert from the given kind of "week calendar".
-- Invalid week and day values will be clipped to the correct range.
fromWeekCalendar ::
    FirstWeekType
    -- ^ how to reckon the first week of the year
    -> DayOfWeek
    -- ^ the first day of each week
    -> Year -> WeekOfYear -> DayOfWeek -> Day
fromWeekCalendar :: FirstWeekType
-> DayOfWeek -> Integer -> WeekOfYear -> DayOfWeek -> Day
fromWeekCalendar FirstWeekType
wt DayOfWeek
ws Integer
y WeekOfYear
wy DayOfWeek
dw = let
    d1 :: Day
    d1 :: Day
d1 = FirstWeekType -> DayOfWeek -> Integer -> Day
firstDayOfWeekCalendar FirstWeekType
wt DayOfWeek
ws Integer
y
    wy' :: WeekOfYear
wy' = WeekOfYear -> WeekOfYear -> WeekOfYear -> WeekOfYear
forall t. Ord t => t -> t -> t -> t
clip WeekOfYear
1 WeekOfYear
53 WeekOfYear
wy
    getday :: WeekOfYear -> Day
    getday :: WeekOfYear -> Day
getday WeekOfYear
wy'' = Integer -> Day -> Day
addDays (WeekOfYear -> Integer
forall a. Integral a => a -> Integer
toInteger (WeekOfYear -> Integer) -> WeekOfYear -> Integer
forall a b. (a -> b) -> a -> b
$ (WeekOfYear -> WeekOfYear
forall a. Enum a => a -> a
pred WeekOfYear
wy'' WeekOfYear -> WeekOfYear -> WeekOfYear
forall a. Num a => a -> a -> a
* WeekOfYear
7) WeekOfYear -> WeekOfYear -> WeekOfYear
forall a. Num a => a -> a -> a
+ (DayOfWeek -> DayOfWeek -> WeekOfYear
dayOfWeekDiff DayOfWeek
dw DayOfWeek
ws)) Day
d1
    d1s :: Day
d1s = FirstWeekType -> DayOfWeek -> Integer -> Day
firstDayOfWeekCalendar FirstWeekType
wt DayOfWeek
ws (Integer -> Day) -> Integer -> Day
forall a b. (a -> b) -> a -> b
$ Integer -> Integer
forall a. Enum a => a -> a
succ Integer
y
    day :: Day
day = WeekOfYear -> Day
getday WeekOfYear
wy'
    in if WeekOfYear
wy' WeekOfYear -> WeekOfYear -> Bool
forall a. Eq a => a -> a -> Bool
== WeekOfYear
53 then if Day
day Day -> Day -> Bool
forall a. Ord a => a -> a -> Bool
>= Day
d1s then WeekOfYear -> Day
getday WeekOfYear
52 else Day
day else Day
day

-- | Convert from the given kind of "week calendar".
-- Invalid week and day values will return Nothing.
fromWeekCalendarValid ::
     FirstWeekType
    -- ^ how to reckon the first week of the year
    -> DayOfWeek
    -- ^ the first day of each week
    -> Year -> WeekOfYear -> DayOfWeek -> Maybe Day
fromWeekCalendarValid :: FirstWeekType
-> DayOfWeek -> Integer -> WeekOfYear -> DayOfWeek -> Maybe Day
fromWeekCalendarValid FirstWeekType
wt DayOfWeek
ws Integer
y WeekOfYear
wy DayOfWeek
dw = let
    d :: Day
d = FirstWeekType
-> DayOfWeek -> Integer -> WeekOfYear -> DayOfWeek -> Day
fromWeekCalendar FirstWeekType
wt DayOfWeek
ws Integer
y WeekOfYear
wy DayOfWeek
dw
    in if FirstWeekType
-> DayOfWeek -> Day -> (Integer, WeekOfYear, DayOfWeek)
toWeekCalendar FirstWeekType
wt DayOfWeek
ws Day
d (Integer, WeekOfYear, DayOfWeek)
-> (Integer, WeekOfYear, DayOfWeek) -> Bool
forall a. Eq a => a -> a -> Bool
== (Integer
y,WeekOfYear
wy,DayOfWeek
dw) then Day -> Maybe Day
forall a. a -> Maybe a
Just Day
d else Maybe Day
forall a. Maybe a
Nothing

-- | Convert to ISO 8601 Week Date format. First element of result is year, second week number (1-53), third day of week (1 for Monday to 7 for Sunday).
-- Note that \"Week\" years are not quite the same as Gregorian years, as the first day of the year is always a Monday.
-- The first week of a year is the first week to contain at least four days in the corresponding Gregorian year.
toWeekDate :: Day -> (Year, WeekOfYear, Int)
toWeekDate :: Day -> (Integer, WeekOfYear, WeekOfYear)
toWeekDate Day
d = let
    (Integer
y,WeekOfYear
wy,DayOfWeek
dw) = FirstWeekType
-> DayOfWeek -> Day -> (Integer, WeekOfYear, DayOfWeek)
toWeekCalendar FirstWeekType
FirstMostWeek DayOfWeek
Monday Day
d
    in (Integer
y,WeekOfYear
wy,DayOfWeek -> WeekOfYear
forall a. Enum a => a -> WeekOfYear
fromEnum DayOfWeek
dw)

-- | Convert from ISO 8601 Week Date format. First argument is year, second week number (1-52 or 53), third day of week (1 for Monday to 7 for Sunday).
-- Invalid week and day values will be clipped to the correct range.
fromWeekDate :: Year -> WeekOfYear -> Int -> Day
fromWeekDate :: Integer -> WeekOfYear -> WeekOfYear -> Day
fromWeekDate Integer
y WeekOfYear
wy WeekOfYear
dw = FirstWeekType
-> DayOfWeek -> Integer -> WeekOfYear -> DayOfWeek -> Day
fromWeekCalendar FirstWeekType
FirstMostWeek DayOfWeek
Monday Integer
y WeekOfYear
wy (WeekOfYear -> DayOfWeek
forall a. Enum a => WeekOfYear -> a
toEnum (WeekOfYear -> DayOfWeek) -> WeekOfYear -> DayOfWeek
forall a b. (a -> b) -> a -> b
$ WeekOfYear -> WeekOfYear -> WeekOfYear -> WeekOfYear
forall t. Ord t => t -> t -> t -> t
clip WeekOfYear
1 WeekOfYear
7 WeekOfYear
dw)

-- | Bidirectional abstract constructor for ISO 8601 Week Date format.
-- Invalid week values will be clipped to the correct range.
pattern YearWeekDay :: Year -> WeekOfYear -> DayOfWeek -> Day
pattern $mYearWeekDay :: forall {r}.
Day
-> (Integer -> WeekOfYear -> DayOfWeek -> r) -> ((# #) -> r) -> r
$bYearWeekDay :: Integer -> WeekOfYear -> DayOfWeek -> Day
YearWeekDay y wy dw <- (toWeekDate -> (y,wy,toEnum -> dw)) where
    YearWeekDay Integer
y WeekOfYear
wy DayOfWeek
dw = Integer -> WeekOfYear -> WeekOfYear -> Day
fromWeekDate Integer
y WeekOfYear
wy (DayOfWeek -> WeekOfYear
forall a. Enum a => a -> WeekOfYear
fromEnum DayOfWeek
dw)

#if __GLASGOW_HASKELL__ >= 802
{-# COMPLETE YearWeekDay #-}
#endif

-- | Convert from ISO 8601 Week Date format. First argument is year, second week number (1-52 or 53), third day of week (1 for Monday to 7 for Sunday).
-- Invalid week and day values will return Nothing.
fromWeekDateValid :: Year -> WeekOfYear -> Int -> Maybe Day
fromWeekDateValid :: Integer -> WeekOfYear -> WeekOfYear -> Maybe Day
fromWeekDateValid Integer
y WeekOfYear
wy WeekOfYear
dwr = do
    WeekOfYear
dw <- WeekOfYear -> WeekOfYear -> WeekOfYear -> Maybe WeekOfYear
forall t. Ord t => t -> t -> t -> Maybe t
clipValid WeekOfYear
1 WeekOfYear
7 WeekOfYear
dwr
    FirstWeekType
-> DayOfWeek -> Integer -> WeekOfYear -> DayOfWeek -> Maybe Day
fromWeekCalendarValid FirstWeekType
FirstMostWeek DayOfWeek
Monday Integer
y WeekOfYear
wy (WeekOfYear -> DayOfWeek
forall a. Enum a => WeekOfYear -> a
toEnum WeekOfYear
dw)

-- | Show in ISO 8601 Week Date format as yyyy-Www-d (e.g. \"2006-W46-3\").
showWeekDate :: Day -> String
showWeekDate :: Day -> String
showWeekDate Day
date = (Integer -> String
forall t. ShowPadded t => t -> String
show4 Integer
y) String -> String -> String
forall a. [a] -> [a] -> [a]
++ String
"-W" String -> String -> String
forall a. [a] -> [a] -> [a]
++ (WeekOfYear -> String
forall t. ShowPadded t => t -> String
show2 WeekOfYear
w) String -> String -> String
forall a. [a] -> [a] -> [a]
++ String
"-" String -> String -> String
forall a. [a] -> [a] -> [a]
++ (WeekOfYear -> String
forall a. Show a => a -> String
show WeekOfYear
d)
  where
    (Integer
y, WeekOfYear
w, WeekOfYear
d) = Day -> (Integer, WeekOfYear, WeekOfYear)
toWeekDate Day
date