//! Widgets for displaying progress indicators.

use std::ops::RangeInclusive;
use std::time::Duration;

use kludgine::figures::Ranged;

use crate::animation::easings::{EaseInOutQuadradic, EaseOutQuadradic};
use crate::animation::{
    AnimationHandle, AnimationTarget, IntoAnimate, PercentBetween, Spawn, ZeroToOne,
};
use crate::value::{Dynamic, IntoDynamic, IntoValue, MapEach, Value};
use crate::widget::{MakeWidget, WidgetInstance};
use crate::widgets::slider::Slidable;
use crate::widgets::Data;

/// A bar-shaped progress indicator.
#[derive(Debug)]
pub struct ProgressBar {
    progress: Value<Progress>,
}

impl ProgressBar {
    /// Returns an indeterminant progress bar.
    #[must_use]
    pub const fn indeterminant() -> Self {
        Self {
            progress: Value::Constant(Progress::Indeterminant),
        }
    }

    /// Returns a new progress bar that displays `progress`.
    #[must_use]
    pub fn new(progress: impl IntoDynamic<Progress>) -> Self {
        Self {
            progress: Value::Dynamic(progress.into_dynamic()),
        }
    }
}

/// A measurement of progress for an indicator widget like [`ProgressBar`].
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum Progress<T = ZeroToOne> {
    /// The task has an indeterminant length.
    Indeterminant,
    /// The task is a specified amount complete.
    Percent(T),
}

impl MakeWidget for ProgressBar {
    fn make_widget(self) -> WidgetInstance {
        let start = Dynamic::new(ZeroToOne::ZERO);
        let end = Dynamic::new(ZeroToOne::ZERO);
        let value = (&start, &end).map_each(|(start, end)| *start..=*end);

        let mut indeterminant_animation = None;
        update_progress_bar(
            self.progress.get(),
            &mut indeterminant_animation,
            &start,
            &end,
        );

        let slider = value.slider().knobless().non_interactive();
        match self.progress {
            Value::Dynamic(progress) => {
                progress.for_each(move |progress| {
                    update_progress_bar(*progress, &mut indeterminant_animation, &start, &end);
                });
                Data::new_wrapping(progress, slider).make_widget()
            }
            Value::Constant(_) => Data::new_wrapping(indeterminant_animation, slider).make_widget(),
        }
    }
}

fn update_progress_bar(
    progress: Progress,
    indeterminant_animation: &mut Option<AnimationHandle>,
    start: &Dynamic<ZeroToOne>,
    end: &Dynamic<ZeroToOne>,
) {
    match progress {
        Progress::Indeterminant => {
            if indeterminant_animation.is_none() {
                *indeterminant_animation = Some(
                    (
                        start.transition_to(ZeroToOne::ZERO),
                        end.transition_to(ZeroToOne::ZERO),
                    )
                        .immediately()
                        .and_then(
                            end.transition_to(ZeroToOne::new(0.75))
                                .over(Duration::from_millis(500))
                                .with_easing(EaseOutQuadradic),
                        )
                        .and_then(
                            start
                                .transition_to(ZeroToOne::new(0.25))
                                .over(Duration::from_millis(500))
                                .with_easing(EaseOutQuadradic),
                        )
                        .and_then(
                            end.transition_to(ZeroToOne::ONE)
                                .over(Duration::from_millis(250))
                                .with_easing(EaseOutQuadradic),
                        )
                        .and_then(
                            start
                                .transition_to(ZeroToOne::ONE)
                                .over(Duration::from_millis(250))
                                .with_easing(EaseInOutQuadradic),
                        )
                        .cycle()
                        .spawn(),
                );
            }
        }
        Progress::Percent(value) => {
            let _stopped_animation = indeterminant_animation.take();
            start.set(ZeroToOne::ZERO);
            end.set(value);
        }
    }
}

/// A value that can be used in a progress indicator.
pub trait Progressable<T>: IntoDynamic<T> + Sized
where
    T: ProgressValue + Send,
{
    /// Returns a new progress bar that displays progress from `T::MIN` to
    /// `T::MAX`.
    fn progress_bar(self) -> ProgressBar {
        ProgressBar::new(
            self.into_dynamic()
                .map_each(|value| value.to_progress(None)),
        )
    }

    /// Returns a new progress bar that displays progress from `T::MIN` to
    /// `max`. The maximum value can be either a `T` or an `Option<T>`. If
    /// `None` is the maximum value, an indeterminant progress bar will be
    /// displayed.
    fn progress_bar_to(self, max: impl IntoValue<T::Value>) -> ProgressBar
    where
        T: Send,
        T::Value: PartialEq + Ranged + Send + Clone,
    {
        let max = max.into_value();
        match max {
            Value::Constant(max) => self.progress_bar_between(<T::Value>::MIN..=max),
            Value::Dynamic(max) => {
                self.progress_bar_between(max.map_each(|max| <T::Value>::MIN..=max.clone()))
            }
        }
    }

    /// Returns a new progress bar that displays progress over the specified
    /// `range` of `T`. The range can be either a `T..=T` or an `Option<T>`. If
    /// `None` is specified as the range, an indeterminant progress bar will be
    /// displayed.
    fn progress_bar_between<Range>(self, range: Range) -> ProgressBar
    where
        T: Send,
        T::Value: Send,
        Range: IntoValue<RangeInclusive<T::Value>>,
    {
        let value = self.into_dynamic();
        let range = range.into_value();
        match range {
            Value::Constant(range) => ProgressBar::new(
                value.map_each(move |value| value.to_progress(Some(range.start()..=range.end()))),
            ),
            Value::Dynamic(range) => {
                ProgressBar::new((&range, &value).map_each(|(range, value)| {
                    value.to_progress(Some(range.start()..=range.end()))
                }))
            }
        }
    }
}

impl<U> Progressable<U> for Dynamic<U> where U: ProgressValue + Send {}

/// A value that can be used in a progress indicator.
pub trait ProgressValue: 'static {
    /// The type that progress is ranged over.
    type Value;

    /// Converts this value to a progress using the range given, if provided. If
    /// no range is provided, the full range of the type should be considered.
    fn to_progress(&self, range: Option<RangeInclusive<&Self::Value>>) -> Progress;
}

impl<T> ProgressValue for T
where
    T: Ranged + PercentBetween + 'static,
{
    type Value = T;

    fn to_progress(&self, range: Option<RangeInclusive<&Self::Value>>) -> Progress {
        if let Some(range) = range {
            Progress::Percent(self.percent_between(range.start(), range.end()))
        } else {
            Progress::Percent(self.percent_between(&T::MIN, &T::MAX))
        }
    }
}

impl<T> ProgressValue for Option<T>
where
    T: Ranged + PercentBetween + 'static,
{
    type Value = T;

    fn to_progress(&self, range: Option<RangeInclusive<&Self::Value>>) -> Progress {
        self.as_ref()
            .map_or(Progress::Indeterminant, |value| value.to_progress(range))
    }
}

impl<T> ProgressValue for Progress<T>
where
    T: Ranged + PercentBetween + 'static,
{
    type Value = T;

    fn to_progress(&self, range: Option<RangeInclusive<&Self::Value>>) -> Progress {
        match self {
            Progress::Indeterminant => Progress::Indeterminant,
            Progress::Percent(value) => value.to_progress(range),
        }
    }
}