//! Date and time types unconcerned with timezones.

//!

//! They are primarily building blocks for other types

//! (e.g. [`TimeZone`](../offset/trait.TimeZone.html)),

//! but can be also used for the simpler date and time handling.

use core::hash::{Hash, Hasher};

use core::ops::RangeInclusive;

use crate::Weekday;

use crate::expect;

pub(crate) mod date;

pub(crate) mod datetime;

mod internals;

pub(crate) mod isoweek;

pub(crate) mod time;

#[allow(deprecated)]

pub use self::date::{MAX_DATE, MIN_DATE};

pub use self::date::{NaiveDate, NaiveDateDaysIterator, NaiveDateWeeksIterator};

#[allow(deprecated)]

pub use self::datetime::{MAX_DATETIME, MIN_DATETIME, NaiveDateTime};

pub use self::isoweek::IsoWeek;

pub use self::time::NaiveTime;

#[cfg(feature = "__internal_bench")]

#[doc(hidden)]

pub use self::internals::YearFlags as __BenchYearFlags;

/// A week represented by a [`NaiveDate`] and a [`Weekday`] which is the first

/// day of the week.

#[derive(Clone, Copy, Debug, Eq)]

pub struct NaiveWeek {

    date: NaiveDate,

    start: Weekday,

}

impl NaiveWeek {

    /// Create a new `NaiveWeek`

    pub(crate) const fn new(date: NaiveDate, start: Weekday) -> Self {

        Self { date, start }

    }

    /// Returns a date representing the first day of the week.

    ///

    /// # Panics

    ///

    /// Panics if the first day of the week happens to fall just out of range of `NaiveDate`

    /// (more than ca. 262,000 years away from common era).

    ///

    /// # Examples

    ///

    /// ```

    /// use chrono::{NaiveDate, Weekday};

    ///

    /// let date = NaiveDate::from_ymd_opt(2022, 4, 18).unwrap();

    /// let week = date.week(Weekday::Mon);

    /// assert!(week.first_day() <= date);

    /// ```

    #[inline]

    #[must_use]

    pub const fn first_day(&self) -> NaiveDate {

        expect(self.checked_first_day(), "first weekday out of range for `NaiveDate`")

    }

    /// Returns a date representing the first day of the week or

    /// `None` if the date is out of `NaiveDate`'s range

    /// (more than ca. 262,000 years away from common era).

    ///

    /// # Examples

    ///

    /// ```

    /// use chrono::{NaiveDate, Weekday};

    ///

    /// let date = NaiveDate::MIN;

    /// let week = date.week(Weekday::Mon);

    /// if let Some(first_day) = week.checked_first_day() {

    ///     assert!(first_day == date);

    /// } else {

    ///     // error handling code

    ///     return;

    /// };

    /// ```

    #[inline]

    #[must_use]

    pub const fn checked_first_day(&self) -> Option<NaiveDate> {

        let start = self.start.num_days_from_monday() as i32;

        let ref_day = self.date.weekday().num_days_from_monday() as i32;

        // Calculate the number of days to subtract from `self.date`.

        // Do not construct an intermediate date beyond `self.date`, because that may be out of

        // range if `date` is close to `NaiveDate::MAX`.

        let days = start - ref_day - if start > ref_day { 7 } else { 0 };

        self.date.add_days(days)

    }

    /// Returns a date representing the last day of the week.

    ///

    /// # Panics

    ///

    /// Panics if the last day of the week happens to fall just out of range of `NaiveDate`

    /// (more than ca. 262,000 years away from common era).

    ///

    /// # Examples

    ///

    /// ```

    /// use chrono::{NaiveDate, Weekday};

    ///

    /// let date = NaiveDate::from_ymd_opt(2022, 4, 18).unwrap();

    /// let week = date.week(Weekday::Mon);

    /// assert!(week.last_day() >= date);

    /// ```

    #[inline]

    #[must_use]

    pub const fn last_day(&self) -> NaiveDate {

        expect(self.checked_last_day(), "last weekday out of range for `NaiveDate`")

    }

    /// Returns a date representing the last day of the week or

    /// `None` if the date is out of `NaiveDate`'s range

    /// (more than ca. 262,000 years away from common era).

    ///

    /// # Examples

    ///

    /// ```

    /// use chrono::{NaiveDate, Weekday};

    ///

    /// let date = NaiveDate::MAX;

    /// let week = date.week(Weekday::Mon);

    /// if let Some(last_day) = week.checked_last_day() {

    ///     assert!(last_day == date);

    /// } else {

    ///     // error handling code

    ///     return;

    /// };

    /// ```

    #[inline]

    #[must_use]

    pub const fn checked_last_day(&self) -> Option<NaiveDate> {

        let end = self.start.pred().num_days_from_monday() as i32;

        let ref_day = self.date.weekday().num_days_from_monday() as i32;

        // Calculate the number of days to add to `self.date`.

        // Do not construct an intermediate date before `self.date` (like with `first_day()`),

        // because that may be out of range if `date` is close to `NaiveDate::MIN`.

        let days = end - ref_day + if end < ref_day { 7 } else { 0 };

        self.date.add_days(days)

    }

    /// Returns a [`RangeInclusive<T>`] representing the whole week bounded by

    /// [first_day](NaiveWeek::first_day) and [last_day](NaiveWeek::last_day) functions.

    ///

    /// # Panics

    ///

    /// Panics if the either the first or last day of the week happens to fall just out of range of

    /// `NaiveDate` (more than ca. 262,000 years away from common era).

    ///

    /// # Examples

    ///

    /// ```

    /// use chrono::{NaiveDate, Weekday};

    ///

    /// let date = NaiveDate::from_ymd_opt(2022, 4, 18).unwrap();

    /// let week = date.week(Weekday::Mon);

    /// let days = week.days();

    /// assert!(days.contains(&date));

    /// ```

    #[inline]

    #[must_use]

    pub const fn days(&self) -> RangeInclusive<NaiveDate> {

        // `expect` doesn't work because `RangeInclusive` is not `Copy`

        match self.checked_days() {

            Some(val) => val,

            None => panic!("{}", "first or last weekday is out of range for `NaiveDate`"),

        }

    }

    /// Returns an [`Option<RangeInclusive<T>>`] representing the whole week bounded by

    /// [checked_first_day](NaiveWeek::checked_first_day) and

    /// [checked_last_day](NaiveWeek::checked_last_day) functions.

    ///

    /// Returns `None` if either of the boundaries are out of `NaiveDate`'s range

    /// (more than ca. 262,000 years away from common era).

    ///

    ///

    /// # Examples

    ///

    /// ```

    /// use chrono::{NaiveDate, Weekday};

    ///

    /// let date = NaiveDate::MAX;

    /// let week = date.week(Weekday::Mon);

    /// let _days = match week.checked_days() {

    ///     Some(d) => d,

    ///     None => {

    ///         // error handling code

    ///         return;

    ///     }

    /// };

    /// ```

    #[inline]

    #[must_use]

    pub const fn checked_days(&self) -> Option<RangeInclusive<NaiveDate>> {

        match (self.checked_first_day(), self.checked_last_day()) {

            (Some(first), Some(last)) => Some(first..=last),

            (_, _) => None,

        }

    }

}

impl PartialEq for NaiveWeek {

    fn eq(&self, other: &Self) -> bool {

        self.first_day() == other.first_day()

    }

}

impl Hash for NaiveWeek {

    fn hash<H: Hasher>(&self, state: &mut H) {

        self.first_day().hash(state);

    }

}

/// A duration in calendar days.

///

/// This is useful because when using `TimeDelta` it is possible that adding `TimeDelta::days(1)`

/// doesn't increment the day value as expected due to it being a fixed number of seconds. This

/// difference applies only when dealing with `DateTime<TimeZone>` data types and in other cases

/// `TimeDelta::days(n)` and `Days::new(n)` are equivalent.

#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq, PartialOrd, Ord)]

pub struct Days(pub(crate) u64);

impl Days {

    /// Construct a new `Days` from a number of days

    pub const fn new(num: u64) -> Self {

        Self(num)

    }

}

/// Serialization/Deserialization of `NaiveDateTime` in alternate formats

///

/// The various modules in here are intended to be used with serde's [`with` annotation] to

/// serialize as something other than the default ISO 8601 format.

///

/// [`with` annotation]: https://serde.rs/field-attrs.html#with

#[cfg(feature = "serde")]

pub mod serde {

    pub use super::datetime::serde::*;

}

#[cfg(test)]

mod test {

    use crate::{NaiveDate, NaiveWeek, Weekday};

    use std::hash::{DefaultHasher, Hash, Hasher};

    #[test]

    fn test_naiveweek() {

        let date = NaiveDate::from_ymd_opt(2022, 5, 18).unwrap();

        let asserts = [

            (Weekday::Mon, "Mon 2022-05-16", "Sun 2022-05-22"),

            (Weekday::Tue, "Tue 2022-05-17", "Mon 2022-05-23"),

            (Weekday::Wed, "Wed 2022-05-18", "Tue 2022-05-24"),

            (Weekday::Thu, "Thu 2022-05-12", "Wed 2022-05-18"),

            (Weekday::Fri, "Fri 2022-05-13", "Thu 2022-05-19"),

            (Weekday::Sat, "Sat 2022-05-14", "Fri 2022-05-20"),

            (Weekday::Sun, "Sun 2022-05-15", "Sat 2022-05-21"),

        ];

        for (start, first_day, last_day) in asserts {

            let week = date.week(start);

            let days = week.days();

            assert_eq!(Ok(week.first_day()), NaiveDate::parse_from_str(first_day, "%a %Y-%m-%d"));

            assert_eq!(Ok(week.last_day()), NaiveDate::parse_from_str(last_day, "%a %Y-%m-%d"));

            assert!(days.contains(&date));

        }

    }

    #[test]

    fn test_naiveweek_min_max() {

        let date_max = NaiveDate::MAX;

        assert!(date_max.week(Weekday::Mon).first_day() <= date_max);

        let date_min = NaiveDate::MIN;

        assert!(date_min.week(Weekday::Mon).last_day() >= date_min);

    }

    #[test]

    fn test_naiveweek_checked_no_panic() {

        let date_max = NaiveDate::MAX;

        if let Some(last) = date_max.week(Weekday::Mon).checked_last_day() {

            assert!(last == date_max);

        }

        let date_min = NaiveDate::MIN;

        if let Some(first) = date_min.week(Weekday::Mon).checked_first_day() {

            assert!(first == date_min);

        }

        let _ = date_min.week(Weekday::Mon).checked_days();

        let _ = date_max.week(Weekday::Mon).checked_days();

    }

    #[test]

    fn test_naiveweek_eq() {

        let a =

            NaiveWeek { date: NaiveDate::from_ymd_opt(2025, 4, 3).unwrap(), start: Weekday::Mon };

        let b =

            NaiveWeek { date: NaiveDate::from_ymd_opt(2025, 4, 4).unwrap(), start: Weekday::Mon };

        assert_eq!(a, b);

        let c =

            NaiveWeek { date: NaiveDate::from_ymd_opt(2025, 4, 3).unwrap(), start: Weekday::Sun };

        assert_ne!(a, c);

        assert_ne!(b, c);

    }

    #[test]

    fn test_naiveweek_hash() {

        let a =

            NaiveWeek { date: NaiveDate::from_ymd_opt(2025, 4, 3).unwrap(), start: Weekday::Mon };

        let b =

            NaiveWeek { date: NaiveDate::from_ymd_opt(2025, 4, 4).unwrap(), start: Weekday::Mon };

        let c =

            NaiveWeek { date: NaiveDate::from_ymd_opt(2025, 4, 3).unwrap(), start: Weekday::Sun };

        let mut hasher = DefaultHasher::default();

        a.hash(&mut hasher);

        let a_hash = hasher.finish();

        hasher = DefaultHasher::default();

        b.hash(&mut hasher);

        let b_hash = hasher.finish();

        hasher = DefaultHasher::default();

        c.hash(&mut hasher);

        let c_hash = hasher.finish();

        assert_eq!(a_hash, b_hash);

        assert_ne!(b_hash, c_hash);

        assert_ne!(a_hash, c_hash);

    }

}