use std::{
    fmt::Display,
    num::{NonZero, NonZeroU32, NonZeroU64},
    rc::Rc,
    str::FromStr,
};

use editor::{Editor, EditorStyle};
use gpui::{ClickEvent, Entity, FocusHandle, Focusable, FontWeight, Modifiers};

use settings::{CenteredPaddingSettings, CodeFade, DelayMs, InactiveOpacity, MinimumContrast};
use ui::prelude::*;

#[derive(Debug, Default, Clone, Copy, PartialEq, Eq, Hash)]
pub enum NumberFieldMode {
    #[default]
    Read,
    Edit,
}

pub trait NumberFieldType: Display + Copy + Clone + Sized + PartialOrd + FromStr + 'static {
    fn default_format(value: &Self) -> String {
        format!("{}", value)
    }
    fn default_step() -> Self;
    fn large_step() -> Self;
    fn small_step() -> Self;
    fn min_value() -> Self;
    fn max_value() -> Self;
    fn saturating_add(self, rhs: Self) -> Self;
    fn saturating_sub(self, rhs: Self) -> Self;
}

macro_rules! impl_newtype_numeric_stepper_float {
    ($type:ident, $default:expr, $large:expr, $small:expr, $min:expr, $max:expr) => {
        impl NumberFieldType for $type {
            fn default_step() -> Self {
                $default.into()
            }

            fn large_step() -> Self {
                $large.into()
            }

            fn small_step() -> Self {
                $small.into()
            }

            fn min_value() -> Self {
                $min.into()
            }

            fn max_value() -> Self {
                $max.into()
            }

            fn saturating_add(self, rhs: Self) -> Self {
                $type((self.0 + rhs.0).min(Self::max_value().0))
            }

            fn saturating_sub(self, rhs: Self) -> Self {
                $type((self.0 - rhs.0).max(Self::min_value().0))
            }
        }
    };
}

macro_rules! impl_newtype_numeric_stepper_int {
    ($type:ident, $default:expr, $large:expr, $small:expr, $min:expr, $max:expr) => {
        impl NumberFieldType for $type {
            fn default_step() -> Self {
                $default.into()
            }

            fn large_step() -> Self {
                $large.into()
            }

            fn small_step() -> Self {
                $small.into()
            }

            fn min_value() -> Self {
                $min.into()
            }

            fn max_value() -> Self {
                $max.into()
            }

            fn saturating_add(self, rhs: Self) -> Self {
                $type(self.0.saturating_add(rhs.0).min(Self::max_value().0))
            }

            fn saturating_sub(self, rhs: Self) -> Self {
                $type(self.0.saturating_sub(rhs.0).max(Self::min_value().0))
            }
        }
    };
}

#[rustfmt::skip]
impl_newtype_numeric_stepper_float!(FontWeight, 50., 100., 10., FontWeight::THIN, FontWeight::BLACK);
impl_newtype_numeric_stepper_float!(CodeFade, 0.1, 0.2, 0.05, 0.0, 0.9);
impl_newtype_numeric_stepper_float!(InactiveOpacity, 0.1, 0.2, 0.05, 0.0, 1.0);
impl_newtype_numeric_stepper_float!(MinimumContrast, 1., 10., 0.5, 0.0, 106.0);
impl_newtype_numeric_stepper_int!(DelayMs, 100, 500, 10, 0, 2000);
impl_newtype_numeric_stepper_float!(
    CenteredPaddingSettings,
    0.05,
    0.2,
    0.1,
    CenteredPaddingSettings::MIN_PADDING,
    CenteredPaddingSettings::MAX_PADDING
);

macro_rules! impl_numeric_stepper_int {
    ($type:ident) => {
        impl NumberFieldType for $type {
            fn default_step() -> Self {
                1
            }

            fn large_step() -> Self {
                10
            }

            fn small_step() -> Self {
                1
            }

            fn min_value() -> Self {
                <$type>::MIN
            }

            fn max_value() -> Self {
                <$type>::MAX
            }

            fn saturating_add(self, rhs: Self) -> Self {
                self.saturating_add(rhs)
            }

            fn saturating_sub(self, rhs: Self) -> Self {
                self.saturating_sub(rhs)
            }
        }
    };
}

macro_rules! impl_numeric_stepper_nonzero_int {
    ($nonzero:ty, $inner:ty) => {
        impl NumberFieldType for $nonzero {
            fn default_step() -> Self {
                <$nonzero>::new(1).unwrap()
            }

            fn large_step() -> Self {
                <$nonzero>::new(10).unwrap()
            }

            fn small_step() -> Self {
                <$nonzero>::new(1).unwrap()
            }

            fn min_value() -> Self {
                <$nonzero>::MIN
            }

            fn max_value() -> Self {
                <$nonzero>::MAX
            }

            fn saturating_add(self, rhs: Self) -> Self {
                let result = self.get().saturating_add(rhs.get());
                <$nonzero>::new(result.max(1)).unwrap()
            }

            fn saturating_sub(self, rhs: Self) -> Self {
                let result = self.get().saturating_sub(rhs.get()).max(1);
                <$nonzero>::new(result).unwrap()
            }
        }
    };
}

macro_rules! impl_numeric_stepper_float {
    ($type:ident) => {
        impl NumberFieldType for $type {
            fn default_format(value: &Self) -> String {
                format!("{:.2}", value)
            }

            fn default_step() -> Self {
                1.0
            }

            fn large_step() -> Self {
                10.0
            }

            fn small_step() -> Self {
                0.1
            }

            fn min_value() -> Self {
                <$type>::MIN
            }

            fn max_value() -> Self {
                <$type>::MAX
            }

            fn saturating_add(self, rhs: Self) -> Self {
                (self + rhs).clamp(Self::min_value(), Self::max_value())
            }

            fn saturating_sub(self, rhs: Self) -> Self {
                (self - rhs).clamp(Self::min_value(), Self::max_value())
            }
        }
    };
}

impl_numeric_stepper_float!(f32);
impl_numeric_stepper_float!(f64);
impl_numeric_stepper_int!(isize);
impl_numeric_stepper_int!(usize);
impl_numeric_stepper_int!(i32);
impl_numeric_stepper_int!(u32);
impl_numeric_stepper_int!(i64);
impl_numeric_stepper_int!(u64);

impl_numeric_stepper_nonzero_int!(NonZeroU32, u32);
impl_numeric_stepper_nonzero_int!(NonZeroU64, u64);
impl_numeric_stepper_nonzero_int!(NonZero<usize>, usize);

#[derive(RegisterComponent)]
pub struct NumberField<T = usize> {
    id: ElementId,
    value: T,
    focus_handle: FocusHandle,
    mode: Entity<NumberFieldMode>,
    format: Box<dyn FnOnce(&T) -> String>,
    large_step: T,
    small_step: T,
    step: T,
    min_value: T,
    max_value: T,
    on_reset: Option<Box<dyn Fn(&ClickEvent, &mut Window, &mut App) + 'static>>,
    on_change: Rc<dyn Fn(&T, &mut Window, &mut App) + 'static>,
    tab_index: Option<isize>,
}

impl<T: NumberFieldType> NumberField<T> {
    pub fn new(id: impl Into<ElementId>, value: T, window: &mut Window, cx: &mut App) -> Self {
        let id = id.into();

        let (mode, focus_handle) = window.with_id(id.clone(), |window| {
            let mode = window.use_state(cx, |_, _| NumberFieldMode::default());
            let focus_handle = window.use_state(cx, |_, cx| cx.focus_handle());
            (mode, focus_handle)
        });

        Self {
            id,
            mode,
            value,
            focus_handle: focus_handle.read(cx).clone(),
            format: Box::new(T::default_format),
            large_step: T::large_step(),
            step: T::default_step(),
            small_step: T::small_step(),
            min_value: T::min_value(),
            max_value: T::max_value(),
            on_reset: None,
            on_change: Rc::new(|_, _, _| {}),
            tab_index: None,
        }
    }

    pub fn format(mut self, format: impl FnOnce(&T) -> String + 'static) -> Self {
        self.format = Box::new(format);
        self
    }

    pub fn small_step(mut self, step: T) -> Self {
        self.small_step = step;
        self
    }

    pub fn normal_step(mut self, step: T) -> Self {
        self.step = step;
        self
    }

    pub fn large_step(mut self, step: T) -> Self {
        self.large_step = step;
        self
    }

    pub fn min(mut self, min: T) -> Self {
        self.min_value = min;
        self
    }

    pub fn max(mut self, max: T) -> Self {
        self.max_value = max;
        self
    }

    pub fn on_reset(
        mut self,
        on_reset: impl Fn(&ClickEvent, &mut Window, &mut App) + 'static,
    ) -> Self {
        self.on_reset = Some(Box::new(on_reset));
        self
    }

    pub fn tab_index(mut self, tab_index: isize) -> Self {
        self.tab_index = Some(tab_index);
        self
    }

    pub fn on_change(mut self, on_change: impl Fn(&T, &mut Window, &mut App) + 'static) -> Self {
        self.on_change = Rc::new(on_change);
        self
    }
}

impl<T: NumberFieldType> IntoElement for NumberField<T> {
    type Element = gpui::Component<Self>;

    fn into_element(self) -> Self::Element {
        gpui::Component::new(self)
    }
}

impl<T: NumberFieldType> RenderOnce for NumberField<T> {
    fn render(self, window: &mut Window, cx: &mut App) -> impl IntoElement {
        let mut tab_index = self.tab_index;

        let get_step = {
            let large_step = self.large_step;
            let step = self.step;
            let small_step = self.small_step;
            move |modifiers: Modifiers| -> T {
                if modifiers.shift {
                    large_step
                } else if modifiers.alt {
                    small_step
                } else {
                    step
                }
            }
        };

        let bg_color = cx.theme().colors().surface_background;
        let hover_bg_color = cx.theme().colors().element_hover;

        let border_color = cx.theme().colors().border_variant;
        let focus_border_color = cx.theme().colors().border_focused;

        let base_button = |icon: IconName| {
            h_flex()
                .cursor_pointer()
                .p_1p5()
                .size_full()
                .justify_center()
                .overflow_hidden()
                .border_1()
                .border_color(border_color)
                .bg(bg_color)
                .hover(|s| s.bg(hover_bg_color))
                .focus_visible(|s| s.border_color(focus_border_color).bg(hover_bg_color))
                .child(Icon::new(icon).size(IconSize::Small))
        };

        h_flex()
            .id(self.id.clone())
            .track_focus(&self.focus_handle)
            .gap_1()
            .when_some(self.on_reset, |this, on_reset| {
                this.child(
                    IconButton::new("reset", IconName::RotateCcw)
                        .icon_size(IconSize::Small)
                        .when_some(tab_index.as_mut(), |this, tab_index| {
                            *tab_index += 1;
                            this.tab_index(*tab_index - 1)
                        })
                        .on_click(on_reset),
                )
            })
            .child(
                h_flex()
                    .map(|decrement| {
                        let decrement_handler = {
                            let value = self.value;
                            let on_change = self.on_change.clone();
                            let min = self.min_value;
                            move |click: &ClickEvent, window: &mut Window, cx: &mut App| {
                                let step = get_step(click.modifiers());
                                let new_value = value.saturating_sub(step);
                                let new_value = if new_value < min { min } else { new_value };
                                on_change(&new_value, window, cx);
                            }
                        };

                        decrement.child(
                            base_button(IconName::Dash)
                                .id("decrement_button")
                                .rounded_tl_sm()
                                .rounded_bl_sm()
                                .tab_index(
                                    tab_index
                                        .as_mut()
                                        .map(|tab_index| {
                                            *tab_index += 1;
                                            *tab_index - 1
                                        })
                                        .unwrap_or(0),
                                )
                                .on_click(decrement_handler),
                        )
                    })
                    .child(
                        h_flex()
                            .min_w_16()
                            .size_full()
                            .border_y_1()
                            .border_color(border_color)
                            .bg(bg_color)
                            .in_focus(|this| this.border_color(focus_border_color))
                            .child(match *self.mode.read(cx) {
                                NumberFieldMode::Read => h_flex()
                                    .px_1()
                                    .flex_1()
                                    .justify_center()
                                    .child(Label::new((self.format)(&self.value)))
                                    .into_any_element(),
                                // Edit mode is disabled until we implement center text alignment for editor
                                // mode.write(cx, NumberFieldMode::Edit);
                                //
                                // When we get to making Edit mode work, we shouldn't even focus the decrement/increment buttons.
                                // Focus should go instead straight to the editor, avoiding any double-step focus.
                                // In this world, the buttons become a mouse-only interaction, given users should be able
                                // to do everything they'd do with the buttons straight in the editor anyway.
                                NumberFieldMode::Edit => h_flex()
                                    .flex_1()
                                    .child(window.use_state(cx, {
                                        |window, cx| {
                                            let previous_focus_handle = window.focused(cx);
                                            let mut editor = Editor::single_line(window, cx);
                                            let mut style = EditorStyle::default();
                                            style.text.text_align = gpui::TextAlign::Right;
                                            editor.set_style(style, window, cx);

                                            editor.set_text(format!("{}", self.value), window, cx);
                                            cx.on_focus_out(&editor.focus_handle(cx), window, {
                                                let mode = self.mode.clone();
                                                let min = self.min_value;
                                                let max = self.max_value;
                                                let on_change = self.on_change.clone();
                                                move |this, _, window, cx| {
                                                    if let Ok(new_value) =
                                                        this.text(cx).parse::<T>()
                                                    {
                                                        let new_value = if new_value < min {
                                                            min
                                                        } else if new_value > max {
                                                            max
                                                        } else {
                                                            new_value
                                                        };

                                                        if let Some(previous) =
                                                            previous_focus_handle.as_ref()
                                                        {
                                                            window.focus(previous);
                                                        }
                                                        on_change(&new_value, window, cx);
                                                    };
                                                    mode.write(cx, NumberFieldMode::Read);
                                                }
                                            })
                                            .detach();

                                            window.focus(&editor.focus_handle(cx));

                                            editor
                                        }
                                    }))
                                    .on_action::<menu::Confirm>({
                                        move |_, window, _| {
                                            window.blur();
                                        }
                                    })
                                    .into_any_element(),
                            }),
                    )
                    .map(|increment| {
                        let increment_handler = {
                            let value = self.value;
                            let on_change = self.on_change.clone();
                            let max = self.max_value;
                            move |click: &ClickEvent, window: &mut Window, cx: &mut App| {
                                let step = get_step(click.modifiers());
                                let new_value = value.saturating_add(step);
                                let new_value = if new_value > max { max } else { new_value };
                                on_change(&new_value, window, cx);
                            }
                        };

                        increment.child(
                            base_button(IconName::Plus)
                                .id("increment_button")
                                .rounded_tr_sm()
                                .rounded_br_sm()
                                .tab_index(
                                    tab_index
                                        .as_mut()
                                        .map(|tab_index| {
                                            *tab_index += 1;
                                            *tab_index - 1
                                        })
                                        .unwrap_or(0),
                                )
                                .on_click(increment_handler),
                        )
                    }),
            )
    }
}

impl Component for NumberField<usize> {
    fn scope() -> ComponentScope {
        ComponentScope::Input
    }

    fn name() -> &'static str {
        "Number Field"
    }

    fn sort_name() -> &'static str {
        Self::name()
    }

    fn description() -> Option<&'static str> {
        Some("A numeric input element with increment and decrement buttons.")
    }

    fn preview(window: &mut Window, cx: &mut App) -> Option<AnyElement> {
        let stepper_example = window.use_state(cx, |_, _| 100.0);

        Some(
            v_flex()
                .gap_6()
                .children(vec![single_example(
                    "Default Numeric Stepper",
                    NumberField::new(
                        "numeric-stepper-component-preview",
                        *stepper_example.read(cx),
                        window,
                        cx,
                    )
                    .on_change({
                        let stepper_example = stepper_example.clone();
                        move |value, _, cx| stepper_example.write(cx, *value)
                    })
                    .min(1.0)
                    .max(100.0)
                    .into_any_element(),
                )])
                .into_any_element(),
        )
    }
}