flux-tui 0.5.0

use std::{
	cell::RefCell,
	rc::{Rc, Weak},
};

use super::*;
use crate::canvas::GlyphArray;

/// [Window] which is scrollable
pub trait Scrollable: Window {
	/// Can current [Scrollable] be scrolled horizontally / vertically
	fn is_scrollable(&self, axis: Orientation) -> bool;

	/// Scrolls page/line-wise (see [ScrollKind]) in the given direction
	fn scroll(&mut self, direction: Direction, kind: ScrollKind);

	/// Sets the horizontal / vertical offset
	fn set_offset(&mut self, direction: Orientation, offset: usize);

	/// Horizontal / Vertical offset of the scrolled content
	fn offset(&self, axis: Orientation) -> usize;

	/// Horizontal / Vertical size of the viewport for current [Scrollable]
	fn viewport(&self, axis: Orientation) -> usize;

	/// Should only be called by the [ScrollViewer] itself
	fn set_scroll_viewer(&mut self, scroll_viewer: Weak<RefCell<ScrollViewer>>);
}

/// Base struct for storing different information required for the [Scrollable] trait
/// Has all fns of [Scrollable] but doesn't implement the trait
#[derive(Clone, Debug, Default)]
pub struct ScrollBase {
	/// Offset of the base 0,0 coordinate (as in rendering)
	pub offset: Vector2D<usize>,
	/// Viewport for the whole content to be rendered
	pub viewport: Vector2D<usize>,
	/// Actual size rendered
	pub render_size: TPoint,
	/// Weak reference to the owning scroll viewer
	pub scroll_viewer: Weak<RefCell<ScrollViewer>>,
}

impl ScrollBase {
	pub fn is_scrollable(&self, axis: Orientation) -> bool {
		let idx = axis as usize;
		self.scroll_viewer.strong_count() > usize::MIN
			&& ((self.offset[idx] == usize::MIN
				&& self.viewport[idx] > self.render_size[idx] as usize)
				|| self.offset[idx] > usize::MIN)
	}

	pub fn scroll(&mut self, direction: Direction, kind: ScrollKind) {
		let delta = match kind {
			ScrollKind::Line => 1,
			ScrollKind::Page => match direction {
				Direction::Up | Direction::Down => self.render_size.y as usize,
				Direction::Left | Direction::Right => self.render_size.x as usize,
			},
		};
		match direction {
			Direction::Up => {
				if let Some(offset) = self.offset.y.checked_sub(delta) {
					self.offset.y = offset;
				}
				else {
					self.offset.y = usize::MIN;
				}
			}
			Direction::Down => {
				let offset = self.offset.y + delta;
				if offset <= self.viewport.y - delta {
					self.offset.y += delta;
				}
				else {
					self.offset.y = self.viewport.y - delta;
				}
			}
			Direction::Left => {
				if let Some(offset) = self.offset.x.checked_sub(delta) {
					self.offset.x -= offset;
				}
				else {
					self.offset.x = usize::MIN
				}
			}
			Direction::Right => {
				let offset = self.offset.x + delta;
				if offset <= self.viewport.x - delta {
					self.offset.x += delta;
				}
				else {
					self.offset.x = self.viewport.x - delta;
				}
			}
		}
	}

	pub fn set_offset(&mut self, direction: Orientation, offset: usize) {
		match direction {
			Orientation::Horizontal => {
				if offset < self.viewport.x {
					self.offset.x = offset;
				}
				else {
					self.offset.x = self.viewport.x.checked_sub(1).unwrap_or_default();
				}
			}
			Orientation::Vertical => {
				if offset < self.viewport.y {
					self.offset.y = offset;
				}
				else {
					self.offset.y = self.viewport.y.checked_sub(1).unwrap_or_default();
				}
			}
		}
	}

	pub fn offset(&self, axis: Orientation) -> usize {
		match axis {
			Orientation::Horizontal => self.offset.x,
			Orientation::Vertical => self.offset.y,
		}
	}

	pub fn viewport(&self, axis: Orientation) -> usize {
		match axis {
			Orientation::Horizontal => self.viewport.x,
			Orientation::Vertical => self.viewport.y,
		}
	}

	pub fn set_scroll_viewer(&mut self, scroll_viewer: Weak<RefCell<ScrollViewer>>) {
		self.scroll_viewer = scroll_viewer;
	}
}

#[derive(Clone, Copy, Debug)]
pub enum Direction {
	Up,
	Down,
	Left,
	Right,
}

#[derive(Copy, Clone, Debug)]
pub enum ScrollKind {
	Line,
	Page,
}

/// Scrolling container which manages the internal content's scrolling
///
/// Design (optional Border):
///  ```text
/// ┌─────────┐
/// │Child1  ▲│
/// │Child2  ┃│
/// │Child3   │
/// │Child4   │
/// │Child5  ▼│
/// │◀━     ▶ │
/// └─────────┘
/// ```
#[derive(Default)]
pub struct ScrollViewer {
	base: WidgetBase,
	draw_bars: Vector2D<bool>,
	content: Option<Rc<RefCell<dyn Scrollable>>>,
	show_scrollbar: bool,
	size: Vector2D<TSize>,
}

impl ScrollViewer {
	pub const ARROW_UP: Grapheme = Grapheme::new_unchecked("▲", GlyphWidth::Half);
	pub const ARROW_UP_DISABLED: Grapheme = Grapheme::new_unchecked("△", GlyphWidth::Half);
	pub const BAR_MARKER_V: Grapheme = Grapheme::new_unchecked("┃", GlyphWidth::Half);
	pub const ARROW_DOWN: Grapheme = Grapheme::new_unchecked("▼", GlyphWidth::Half);
	pub const ARROW_DOWN_DISABLED: Grapheme = Grapheme::new_unchecked("▽", GlyphWidth::Half);

	pub const ARROW_LEFT: Grapheme = Grapheme::new_unchecked("◀", GlyphWidth::Half);
	pub const ARROW_LEFT_DISABLED: Grapheme = Grapheme::new_unchecked("◁", GlyphWidth::Half);
	pub const BAR_MARKER_H: Grapheme = Grapheme::new_unchecked("━", GlyphWidth::Half);
	pub const ARROW_RIGHT: Grapheme = Grapheme::new_unchecked("▶", GlyphWidth::Half);
	pub const ARROW_RIGHT_DISABLED: Grapheme = Grapheme::new_unchecked("▷", GlyphWidth::Half);

	pub fn set_content(rc: &Rc<RefCell<Self>>, mut content: Option<&Rc<RefCell<dyn Scrollable>>>) {
		if let Some(old) = rc.borrow_mut().content.as_mut() {
			old.borrow_mut().set_scroll_viewer(Weak::new());
		}

		if let Some(cnt) = content.as_mut() {
			cnt.borrow_mut().set_scroll_viewer(Rc::downgrade(rc));
		}
		let brw = &mut rc.borrow_mut();
		brw.content = content.cloned();
		brw.provoke_changed_property(WindowProperty::Children);
	}

	pub fn set_scrollbar_visibility(&mut self, show: bool) {
		self.show_scrollbar = show;
		self.reevaluate_showbars();
	}

	fn reevaluate_showbars(&mut self) {
		if let Some(cnt) = self.content.as_ref() {
			let brw = cnt.borrow();
			let old = self.draw_bars;
			self.draw_bars = Vector2D::new(
				self.size.x > 2 && brw.is_scrollable(Orientation::Vertical) && self.show_scrollbar,
				self.size.y > 2
					&& brw.is_scrollable(Orientation::Horizontal)
					&& self.show_scrollbar,
			);
			if old != self.draw_bars {
				self.provoke_changed_property(WindowProperty::Children);
			}
		}
	}

	fn render_scroller(
		&self,
		array: &mut dyn GlyphArray,
		size: TPoint,
		content: &dyn Scrollable,
		orientation: Orientation,
		other_bar: bool,
	) {
		let (arrow_prev, arrow_next, bar_marker);
		let (arrow_prev_dis, arrow_next_dis);
		let max_size;

		match orientation {
			Orientation::Horizontal => {
				arrow_prev = Self::ARROW_LEFT;
				arrow_prev_dis = Self::ARROW_LEFT_DISABLED;
				arrow_next = Self::ARROW_RIGHT;
				arrow_next_dis = Self::ARROW_RIGHT_DISABLED;
				bar_marker = Self::BAR_MARKER_H;
				max_size = size.x;
			}
			Orientation::Vertical => {
				arrow_prev = Self::ARROW_UP;
				arrow_prev_dis = Self::ARROW_UP_DISABLED;
				arrow_next = Self::ARROW_DOWN;
				arrow_next_dis = Self::ARROW_DOWN_DISABLED;
				bar_marker = Self::BAR_MARKER_V;
				max_size = size.y;
			}
		}

		if max_size > 2 && content.is_scrollable(orientation) {
			let offset = content.offset(orientation);
			let viewport = content.viewport(orientation);

			let mut arrow_up = array.get(TSize::MIN).unwrap();
			if !self.base.enabled || offset == usize::MIN {
				arrow_up.set_grapheme(arrow_prev_dis).ok();
				if let Some(color) = self.base.colors.disabled {
					arrow_up.set_fg(color);
				}
			}
			else {
				arrow_up.set_grapheme(arrow_prev).ok();
			}
			std::mem::drop(arrow_up);

			let render_size = max_size - other_bar as TSize;
			if max_size >= 2 {
				let length = size[orientation as usize] - 2 - other_bar as TSize;
				let start = (offset * length as usize + 1).div_ceil(viewport) as TSize;
				let end = if offset + render_size as usize > viewport {
					length + 1
				}
				else {
					((offset + render_size as usize + 1) * length as usize).div_ceil(viewport)
						as TSize
				};

				for idx in start..end + (start == end) as TSize {
					let mut g = array.get(idx).unwrap();
					g.set_grapheme(bar_marker).ok();
					if let Some(color) = self.base.colors.disabled
						&& !self.base.enabled
					{
						g.set_fg(color);
					}
				}
			}

			let mut arrow_down = array.get(max_size - 1 - other_bar as TSize).unwrap();
			if !self.base.enabled || offset + render_size as usize >= viewport {
				arrow_down.set_grapheme(arrow_next_dis).ok();
				if let Some(color) = self.base.colors.disabled {
					arrow_down.set_fg(color);
				}
			}
			else {
				arrow_down.set_grapheme(arrow_next).ok();
			}
		}
	}


	/// Can current [Scrollable] be scrolled horizontally / vertically
	pub fn is_scrollable(&self, axis: Orientation) -> bool {
		match self.content.as_ref() {
			Some(sc) => sc.borrow().is_scrollable(axis),
			None => false,
		}
	}

	/// Scrolls page/line-wise (see [ScrollKind]) in the given direction
	pub fn scroll(&mut self, direction: Direction, kind: ScrollKind) {
		if let Some(sc) = self.content.as_ref() {
			sc.borrow_mut().scroll(direction, kind);
		}
	}

	/// Sets the horizontal / vertical offset
	pub fn set_offset(&mut self, direction: Orientation, offset: usize) {
		if let Some(sc) = self.content.as_ref() {
			sc.borrow_mut().set_offset(direction, offset);
		}
	}

	/// Horizontal / Vertical offset of the scrolled content
	pub fn offset(&self, axis: Orientation) -> usize {
		match self.content.as_ref() {
			Some(sc) => sc.borrow().offset(axis),
			None => usize::MIN,
		}
	}

	/// Horizontal / Vertical size of the viewport for current [Scrollable]
	pub fn viewport(&self, axis: Orientation) -> usize {
		match self.content.as_ref() {
			Some(sc) => sc.borrow().viewport(axis),
			None => usize::MIN,
		}
	}
}

impl Window for ScrollViewer {
	fn render(&self, canvas: &mut crate::canvas::Canvas) {
		if let Some(content) = self.content.as_ref() {
			let brw = content.borrow();
			let size = canvas.size();
			if self.draw_bars.x {
				self.render_scroller(
					&mut canvas.get_column(size.x - 1, GlyphWidth::Half).unwrap(),
					size,
					&*brw,
					Orientation::Vertical,
					self.draw_bars.y,
				);
			}
			if self.draw_bars.y {
				self.render_scroller(
					&mut canvas.get_row(size.y - 1, GlyphWidth::Half).unwrap(),
					size,
					&*brw,
					Orientation::Horizontal,
					self.draw_bars.x,
				);
			}
		}
	}

	fn handle_event(&mut self, event: &mut WindowEvent) {
		if let Event::Resize(w, h) = event.raw() {
			self.size = Vector2D::new(*w, *h);
			self.reevaluate_showbars();
		}
	}

	fn children(&mut self, mut builder: SubWindowBuilder) -> super::SubWindows {
		if let Some(ch) = self.content.clone() {
			let rect = builder.base_rect();
			builder
				.add_pair(
					ch,
					Some(
						rect.subrect(
							0,
							0,
							rect.size.x - self.draw_bars.x as TSize,
							rect.size.y - self.draw_bars.y as TSize,
						)
						.unwrap(),
					),
				)
				.unwrap();
		}
		builder.build().unwrap()
	}

	fn focus(&self) -> Option<WindowRef> {
		self.content.clone().map(|x| x as Rc<RefCell<dyn Window>>)
	}

	fn is_enabled(&self) -> bool {
		self.base.enabled
	}
}

impl HasWindowUID for ScrollViewer {
	fn uid(&self) -> super::WindowUID {
		self.base.uid
	}
}

impl WindowLayout for ScrollViewer {
	fn desired_size(&self, available_size: TPoint) -> TPoint {
		self.base.desired_size(available_size)
	}

	fn alignment(&self) -> (HorizontalAlignment, VerticalAlignment) {
		self.base.alignment
	}

	fn border(&self) -> BorderStyle {
		self.base.border
	}

	fn is_visible(&self) -> bool {
		self.base.visibility
	}

	fn margin(&self) -> Thickness {
		self.base.margin
	}
}

impl Widget for ScrollViewer {
	fn set_visibility(&mut self, visibility: bool) {
		self.base.visibility = visibility;
		self.provoke_changed_property(WindowProperty::IsVisible);
	}

	fn set_width(&mut self, width: Size) {
		self.base.size.x = width;
		self.provoke_changed_property(WindowProperty::Size);
	}

	fn set_height(&mut self, height: Size) {
		self.base.size.y = height;
		self.provoke_changed_property(WindowProperty::Size);
	}

	fn set_margin(&mut self, margin: Thickness) {
		self.base.margin = margin;
		self.provoke_changed_property(WindowProperty::Margin);
	}

	fn set_border(&mut self, border: BorderStyle) {
		self.base.border = border;
		self.provoke_changed_property(WindowProperty::Border);
	}

	fn set_alignment(&mut self, horizontal: HorizontalAlignment, vertical: VerticalAlignment) {
		self.base.alignment = (horizontal, vertical);
		self.provoke_changed_property(WindowProperty::Alignment);
	}

	fn set_enabled_state(&mut self, is_enabled: bool) {
		self.base.enabled = is_enabled;
		self.provoke_changed_property(WindowProperty::Children);
	}

	fn set_width_constraint(&mut self, width: SizeConstraint) {
		self.base.constraints.x = width;
		self.provoke_changed_property(WindowProperty::Size);
	}

	fn set_height_constraint(&mut self, height: SizeConstraint) {
		self.base.constraints.y = height;
		self.provoke_changed_property(WindowProperty::Size);
	}
}

impl WidgetColors for ScrollViewer {
	fn set_disabled_color(&mut self, color: Option<Color>) {
		self.base.colors.disabled = color;
	}

	fn set_base_fg_color(&mut self, color: Option<Color>) {
		self.base.colors.base_fg = color;
	}

	fn set_base_bg_color(&mut self, color: Option<Color>) {
		self.base.colors.base_bg = color;
	}
}