// This file is part of ICU4X. For terms of use, please see the file
// called LICENSE at the top level of the ICU4X source tree
// (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).

//! Options for configuring [`DurationFormatter`](crate::duration::DurationFormatter).

/// A bag of options for defining how to format duration using [`DurationFormatter`](crate::duration::DurationFormatter).
#[non_exhaustive]
#[derive(Debug, Default, Clone, Copy, PartialEq, Eq)]
pub struct DurationFormatterOptions {
    /// The style that will be applied to units
    /// unless overridden by a specific style.
    pub base: BaseStyle,

    /// Style for year
    pub year: Option<YearStyle>,
    /// Visibility control for year
    pub year_visibility: Option<FieldDisplay>,
    /// Style for month
    pub month: Option<MonthStyle>,
    /// Visibility control for month
    pub month_visibility: Option<FieldDisplay>,
    /// Style for week
    pub week: Option<WeekStyle>,
    /// Visibility control for week
    pub week_visibility: Option<FieldDisplay>,
    /// Style for day
    pub day: Option<DayStyle>,
    /// Visibility control for day
    pub day_visibility: Option<FieldDisplay>,
    /// Style for hour
    pub hour: Option<HourStyle>,
    /// Visibility control for hour
    pub hour_visibility: Option<FieldDisplay>,
    /// Style for minute
    pub minute: Option<MinuteStyle>,
    /// Visibility control for minute
    pub minute_visibility: Option<FieldDisplay>,
    /// Style for second
    pub second: Option<SecondStyle>,
    /// Visibility control for second
    pub second_visibility: Option<FieldDisplay>,
    /// Style for millisecond
    pub millisecond: Option<MilliSecondStyle>,
    /// Visibility control for millisecond
    pub millisecond_visibility: Option<FieldDisplay>,
    /// Style for microsecond
    pub microsecond: Option<MicroSecondStyle>,
    /// Visibility control for microsecond
    pub microsecond_visibility: Option<FieldDisplay>,
    /// Style for nanosecond
    pub nanosecond: Option<NanoSecondStyle>,
    /// Visibility control for nanosecond
    pub nanosecond_visibility: Option<FieldDisplay>,

    /// Number of fractional digits to use when formatting sub-second units (milliseconds, microseconds, nanoseconds).
    /// ### Note:
    /// - Only takes effect when the subsecond units are styled as `Numeric`.
    /// - Zero means no fractional digits.
    pub fractional_digits: FractionalDigits,
}

/// Options for configuring the number of fractional digits to display.
#[derive(Debug, Default, Clone, Copy, PartialEq, Eq)]
pub enum FractionalDigits {
    /// Show as many fractional digits as necessary to display the whole duration,
    /// omitting trailing zeroes after the decimal point.
    #[default]
    ShowAll,
    /// Use the given number of fractional digits.
    /// This value must be in the range 0..=9.
    /// Fractional digits are truncated if necessary.
    Fixed(u8),
}

/// Configures visibility of fields in the formatted string.
#[non_exhaustive]
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum FieldDisplay {
    /// Only display this field if it is non-zero.
    Auto,
    /// Always display this field.
    Always,
}

/// Enum used to process different unit styles in a generic way.
/// Implements `From` and `TryFrom` for all unit enums.
#[non_exhaustive]
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub(crate) enum FieldStyle {
    /// Narrow style (most compact)
    Narrow,
    /// Short style (default)
    Short,
    /// Long style (most verbose)
    Long,
    /// Ensure formatted value is at least two digits long (by appending leading zeroes, if necessary)
    TwoDigit,
    /// Numeric style
    Numeric,
    /// Fractional style
    Fractional,
    /// Digital style
    Digital,
}

macro_rules! derive_style {
    (
        $(
            $(#[$enum_meta:meta])*
            pub enum $enum_name: ident {
                $(
                    $(#[$variant_meta:meta])*
                    $variant: ident
                ),* $(,)?
            }
        )+
    ) => {
        $(
            $(#[$enum_meta])*
            pub enum $enum_name {
                $(
                    $(#[$variant_meta])*
                    $variant,
                )*
            }

            impl From<$enum_name> for FieldStyle {
                fn from(style: $enum_name) -> Self {
                    #[allow(unreachable_patterns)]
                    match style {
                        $(
                            $enum_name::$variant => FieldStyle::$variant,
                        )*
                    }
                }
            }

            impl TryFrom<FieldStyle> for $enum_name {
                type Error = FieldStyle;

                fn try_from(style: FieldStyle) -> Result<Self, Self::Error> {
                    match style {
                        $(
                            FieldStyle::$variant => Ok($enum_name::$variant),
                        )*
                        rest => Err(rest),
                    }
                }
            }
            )+
    };
}

derive_style! {
/// Configures the style of the duration output.
#[non_exhaustive]
#[derive(Debug, Default, Clone, Copy, PartialEq, Eq)]
pub enum BaseStyle {
    /// Narrow style (most compact)
    Narrow,
    #[default]
    /// Short style (default)
    Short,
    /// Long style (most verbose)
    Long,
    /// Digital formatting
    Digital,
}

/// Configures the style of the year field.
#[non_exhaustive]
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum YearStyle {
    /// Narrow style (most compact)
    Narrow,
    /// Short style (default)
    Short,
    /// Long style (most verbose)
    Long,
}

/// Configures the style of the month field.
#[non_exhaustive]
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum MonthStyle {
    /// Narrow style (most compact)
    Narrow,
    /// Short style (default)
    Short,
    /// Long style (most verbose)
    Long,
}

/// Configures the style of the week field.
#[non_exhaustive]
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum WeekStyle {
    /// Narrow style (most compact)
    Narrow,
    /// Short style (default)
    Short,
    /// Long style (most verbose)
    Long,
}

/// Configures the style of the day field.
#[non_exhaustive]
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum DayStyle {
    /// Narrow style (most compact)
    Narrow,
    /// Short style (default)
    Short,
    /// Long style (most verbose)
    Long,
}

/// Configures the style of the hour field.
#[non_exhaustive]
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum HourStyle {
    /// Narrow style (most compact)
    Narrow,
    /// Short style (default)
    Short,
    /// Long style (most verbose)
    Long,
    /// Ensure formatted value is at least two digits long (by appending leading zeroes, if necessary)
    TwoDigit,
    /// Numeric style
    Numeric,
}

/// Configures the style of the minute field.
#[non_exhaustive]
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum MinuteStyle {
    /// Narrow style (most compact)
    Narrow,
    /// Short style (default)
    Short,
    /// Long style (most verbose)
    Long,
    /// Ensure formatted value is at least two digits long (by appending leading zeroes, if necessary)
    TwoDigit,
    /// Numeric style
    Numeric,
}

/// Configures the style of the second field.
#[non_exhaustive]
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum SecondStyle {
    /// Narrow style (most compact)
    Narrow,
    /// Short style (default)
    Short,
    /// Long style (most verbose)
    Long,
    /// Ensure formatted value is at least two digits long (by appending leading zeroes, if necessary)
    TwoDigit,
    /// Numeric style
    Numeric,
}

/// Configures the style of the milliseconds field.
#[non_exhaustive]
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum MilliSecondStyle {
    /// Narrow style (most compact)
    Narrow,
    /// Short style (default)
    Short,
    /// Long style (most verbose)
    Long,
    /// Numeric style
    Numeric,
}

/// Configures the style of the microsecond field.
#[non_exhaustive]
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum MicroSecondStyle {
    /// Narrow style (most compact)
    Narrow,
    /// Short style (default)
    Short,
    /// Long style (most verbose)
    Long,
    /// Numeric style
    Numeric,
}

/// Configures the style of the nanosecond field.
#[non_exhaustive]
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum NanoSecondStyle {
    /// Narrow style (most compact)
    Narrow,
    /// Short style (default)
    Short,
    /// Long style (most verbose)
    Long,
    /// Numeric style
    Numeric,
}
}