guise-ui 1.5.3

//! `Calendar` — a controlled month grid.
//!
//! The parent owns the displayed month and the selection; the calendar just
//! draws and reports clicks. [`DatePicker`](super::DatePicker) wraps one in a
//! dropdown, but it also works standalone (inline pickers, booking ranges).

use std::rc::Rc;

use gpui::prelude::*;
use gpui::{div, px, App, ElementId, FontWeight, IntoElement, SharedString, Window};

use super::date::{month_grid, Date, Weekday};
use crate::devtools::Probed;
use crate::icon::{Icon, IconName};
use crate::theme::{theme, Size};

type SelectHandler = Rc<dyn Fn(Date, &mut Window, &mut App) + 'static>;
type MonthHandler = Rc<dyn Fn(i32, u32, &mut Window, &mut App) + 'static>;

/// Day-cell edge (px) per size token.
fn cell_size(size: Size) -> f32 {
  match size {
    Size::Xs => 26.0,
    Size::Sm => 30.0,
    Size::Md => 34.0,
    Size::Lg => 40.0,
    Size::Xl => 46.0,
  }
}

/// A controlled month-view calendar. Pass the visible `month`, the current
/// selection (`value` or `range`), and handlers; the parent owns all state.
#[derive(IntoElement)]
pub struct Calendar {
  id: ElementId,
  year: i32,
  month: u32,
  value: Option<Date>,
  range: Option<(Date, Option<Date>)>,
  min: Option<Date>,
  max: Option<Date>,
  week_start: Weekday,
  size: Size,
  on_select: Option<SelectHandler>,
  on_month_change: Option<MonthHandler>,
}

impl Calendar {
  /// A calendar showing the month containing `Date::today()`.
  pub fn new(id: impl Into<ElementId>) -> Self {
    let today = Date::today();
    Calendar {
      id: id.into(),
      year: today.year(),
      month: today.month(),
      value: None,
      range: None,
      min: None,
      max: None,
      week_start: Weekday::Sunday,
      size: Size::Sm,
      on_select: None,
      on_month_change: None,
    }
  }

  /// The month to display (`month` is 1–12).
  pub fn month(mut self, year: i32, month: u32) -> Self {
    self.year = year;
    self.month = month.clamp(1, 12);
    self
  }

  /// Single selected date.
  pub fn value(mut self, value: Option<Date>) -> Self {
    self.value = value;
    self
  }

  /// Selected range: a start and an optional end (while picking).
  pub fn range(mut self, start: Date, end: Option<Date>) -> Self {
    self.range = Some((start, end));
    self
  }

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

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

  pub fn week_start(mut self, week_start: Weekday) -> Self {
    self.week_start = week_start;
    self
  }

  pub fn size(mut self, size: Size) -> Self {
    self.size = size;
    self
  }

  /// A day cell was clicked (never fires for min/max-disabled days).
  pub fn on_select(mut self, handler: impl Fn(Date, &mut Window, &mut App) + 'static) -> Self {
    self.on_select = Some(Rc::new(handler));
    self
  }

  /// Prev/next was clicked; receives the new (year, month) to display.
  pub fn on_month_change(
    mut self,
    handler: impl Fn(i32, u32, &mut Window, &mut App) + 'static,
  ) -> Self {
    self.on_month_change = Some(Rc::new(handler));
    self
  }
}

impl RenderOnce for Calendar {
  fn render(self, _window: &mut Window, cx: &mut App) -> impl IntoElement {
    let t = theme(cx);
    let cell = cell_size(self.size);
    let font = t.font_size(self.size);
    let radius = t.radius(Size::Xs) + 2.0;
    let text_color = t.text().hsla();
    let dimmed = t.dimmed().hsla();
    let surface_hover = t.surface_hover().hsla();
    let accent = t.primary();
    let accent_bg = accent.hsla();
    let accent_fg = accent.contrasting().hsla();
    let in_range_bg = accent.alpha(0.12);

    let today = Date::today();
    let first = Date::new(self.year, self.month, 1).unwrap_or(today);
    let title: SharedString = format!("{} {}", first.month_name(), self.year).into();

    let mut header = div().flex().items_center().justify_between().child(
      div()
        .text_size(px(font))
        .font_weight(FontWeight::MEDIUM)
        .text_color(text_color)
        .child(title),
    );
    let mut nav = div().flex().items_center().gap(px(4.0));
    for (key, icon, delta) in [
      ("guise-cal-prev", IconName::ChevronLeft, -1),
      ("guise-cal-next", IconName::ChevronRight, 1),
    ] {
      let target = first.add_months(delta);
      let handler = self.on_month_change.clone();
      nav = nav.child(
        div()
          .id(key)
          .flex()
          .items_center()
          .justify_center()
          .w(px(cell * 0.8))
          .h(px(cell * 0.8))
          .rounded(px(radius))
          .text_color(dimmed)
          .hover(move |s| s.bg(surface_hover))
          .child(Icon::new(icon).size(Size::Sm))
          .on_click(move |_ev, window, cx| {
            if let Some(handler) = &handler {
              handler(target.year(), target.month(), window, cx);
            }
          }),
      );
    }
    header = header.child(nav);

    let mut weekdays = div().flex();
    for i in 0..7 {
      let day = Weekday::from_index(self.week_start.index() + i);
      weekdays = weekdays.child(
        div()
          .w(px(cell))
          .h(px(cell * 0.8))
          .flex()
          .items_center()
          .justify_center()
          .text_size(px(font - 3.0))
          .text_color(dimmed)
          .child(SharedString::new_static(day.short())),
      );
    }

    let grid = month_grid(self.year, self.month, self.week_start);
    let (range_start, range_end) = match self.range {
      Some((start, end)) => (Some(start), end),
      None => (None, None),
    };

    let mut days = div().flex().flex_col();
    for week in grid.chunks(7) {
      let mut row = div().flex();
      for date in week {
        let date = *date;
        let outside = date.month() != self.month;
        let disabled =
          self.min.is_some_and(|min| date < min) || self.max.is_some_and(|max| date > max);
        let selected =
          self.value == Some(date) || range_start == Some(date) || range_end == Some(date);
        let in_range = match (range_start, range_end) {
          (Some(start), Some(end)) => date > start && date < end,
          _ => false,
        };

        let mut day = div()
          .id(("guise-cal-day", date.to_days() as usize))
          .w(px(cell))
          .h(px(cell))
          .flex()
          .items_center()
          .justify_center()
          .rounded(px(radius))
          .text_size(px(font - 1.0))
          .text_color(if outside { dimmed } else { text_color })
          .child(SharedString::from(date.day().to_string()));

        if selected {
          day = day
            .bg(accent_bg)
            .text_color(accent_fg)
            .font_weight(FontWeight::MEDIUM);
        } else if in_range {
          day = day.bg(in_range_bg);
        } else if date == today {
          day = day.border_1().border_color(accent_bg);
        }

        if disabled {
          day = day.opacity(0.35);
        } else {
          if !selected {
            day = day.hover(move |s| s.bg(surface_hover));
          }
          let handler = self.on_select.clone();
          day = day.on_click(move |_ev, window, cx| {
            if let Some(handler) = &handler {
              handler(date, window, cx);
            }
          });
        }
        row = row.child(day);
      }
      days = days.child(row);
    }

    div()
      .id(self.id)
      .flex()
      .flex_col()
      .gap(px(6.0))
      .child(header)
      .child(weekdays)
      .child(days)
      .probe("Calendar")
  }
}