flux-tui 0.5.0

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

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

use crossterm::event::{KeyCode, KeyModifiers};

pub type StackpanelSelectionChangedCallback = dyn Fn(&mut Stackpanel);
pub type StackpanelKeyHandler = fn(&mut Stackpanel, event: &mut WindowEvent);

#[derive(Clone)]
struct Child {
	rc: WindowRef,
	// Offset + len on either x or y axis, depending on Stackpanel.orientation
	offset: usize,
	len: usize,
}

impl Child {
	fn new(rc: WindowRef) -> Self {
		Self {
			rc,
			offset: usize::MIN,
			len: usize::MIN,
		}
	}
}

struct Children {
	items: Vec<Child>,
	focus: usize,
	alignment: Alignment,
}

impl Default for Children {
	fn default() -> Self {
		Self {
			items: Vec::default(),
			focus: usize::MIN,
			alignment: Alignment::Center,
		}
	}
}

//TODO: How to scroll partially?? Extension for Canvas/Rect/etc.?
/// Stackpanel will group multiple windows and arrange them according to the Orientation.
/// It will also allow movement between them using the arrow keys.
/// Default margin is 1.
///
/// Design (optional Border, vertical):
///  ```text
/// ┌─────────┐
/// │Content A│
/// │         │
/// │Content B│
/// └─────────┘
/// ```
///
/// Horizontal:
/// ```text
/// ┌─────────────────────┐
/// │Content A   Content B│
/// └─────────────────────┘
/// ```
pub struct Stackpanel {
	orientation: Orientation,
	margin: u8,
	children: Children,
	base: WidgetBase,
	scroll: ScrollBase,
	callback: Rc<StackpanelSelectionChangedCallback>,
	key_handler: StackpanelKeyHandler,
}

impl Default for Stackpanel {
	fn default() -> Self {
		Self::new(Orientation::Vertical)
	}
}

impl Stackpanel {
	pub fn default_callback(_: &mut Self) {}

	pub fn default_key_handler(&mut self, event: &mut WindowEvent) {
		if let Event::Key(k) = event.raw() {
			let scroll_mode =
				k.modifiers.contains(KeyModifiers::CONTROL) && self.has_scroll_viewer();
			match self.orientation {
				Orientation::Horizontal => match k.code {
					KeyCode::Left => {
						self.scroll(Direction::Left, ScrollKind::Line, scroll_mode);
						event.handled = true;
					}
					KeyCode::Right => {
						self.scroll(Direction::Right, ScrollKind::Line, scroll_mode);
						event.handled = true;
					}
					KeyCode::PageUp => {
						self.scroll(Direction::Left, ScrollKind::Page, scroll_mode);
						event.handled = true;
					}
					KeyCode::PageDown => {
						self.scroll(Direction::Right, ScrollKind::Page, scroll_mode);
						event.handled = true;
					}
					_ => {}
				},
				Orientation::Vertical => match k.code {
					KeyCode::Up => {
						self.scroll(Direction::Up, ScrollKind::Line, scroll_mode);
						event.handled = true;
					}
					KeyCode::Down => {
						self.scroll(Direction::Down, ScrollKind::Line, scroll_mode);
						event.handled = true;
					}
					KeyCode::PageUp => {
						self.scroll(Direction::Up, ScrollKind::Page, scroll_mode);
						event.handled = true;
					}
					KeyCode::PageDown => {
						self.scroll(Direction::Down, ScrollKind::Page, scroll_mode);
						event.handled = true;
					}
					_ => {}
				},
			}
		}
	}

	/// Constructs a new Stackpanel with the given [Orientation]
	pub fn new(orientation: Orientation) -> Self {
		Self {
			orientation,
			margin: 1,
			children: Children::default(),
			base: WidgetBase::default(),
			scroll: ScrollBase::default(),
			callback: Rc::new(Self::default_callback),
			key_handler: Self::default_key_handler,
		}
	}

	pub fn set_selection_changed_callback<F: Fn(&mut Self) + 'static>(&mut self, callback: F) {
		self.callback = Rc::new(callback);
	}

	pub fn set_key_handler(&mut self, f: StackpanelKeyHandler) {
		self.key_handler = f;
	}

	/// Sets the alignment for each child/item within the [Stackpanel]
	pub fn set_item_alignment(&mut self, alignment: Alignment) {
		self.children.alignment = alignment;
		self.provoke_changed_property(WindowProperty::Children);
	}

	pub fn set_orientation(&mut self, orientation: Orientation) {
		self.orientation = orientation;
		self.provoke_changed_property(WindowProperty::Children);
	}

	/// Sets the internal childrens focus
	pub fn set_focus(&mut self, item: &Rc<RefCell<dyn Window>>) {
		let uid = item.borrow().uid();
		self.children.focus = self
			.children
			.items
			.iter()
			.position(|x| x.rc.borrow().uid() == uid)
			.unwrap_or_default();
		self.provoke_changed_property(WindowProperty::Focus);
	}

	/// Sets the offset between each child
	pub fn set_child_margin(&mut self, margin: u8) {
		self.margin = margin;
	}

	fn is_selection_visible(&self) -> bool {
		let idx = self.orientation as usize;
		let focus = &self.children.items[self.children.focus];
		focus.offset >= self.scroll.offset[idx]
			&& (focus.offset + focus.len)
				< (self.scroll.offset[idx] + self.scroll.render_size[idx] as usize)
	}

	fn make_selection_visible(&mut self) {
		let child = &self.children.items[self.children.focus];
		let render_size = self.scroll.render_size[self.orientation as usize];
		if let Some(new_offset) = self
			.children
			.items
			.iter()
			.map(|x| x.offset)
			.find(|x| x + render_size as usize >= child.offset + child.len)
		{
			self.scroll.set_offset(self.orientation, new_offset);
			self.provoke_changed_property(WindowProperty::Children);
		}
	}

	/// scroll_only specifies whether selection should also change if only the view changes
	pub fn scroll(&mut self, direction: Direction, kind: ScrollKind, scroll_only: bool) {
		match kind {
			ScrollKind::Line => match direction {
				Direction::Left | Direction::Up => self.move_previous(scroll_only),
				Direction::Right | Direction::Down => self.move_next(scroll_only),
			},
			ScrollKind::Page => match scroll_only {
				true => self.scroll.scroll(direction, kind),
				false => {
					let delta = self.scroll.render_size[self.orientation as usize] as usize;
					let min_offset = match direction {
						Direction::Left | Direction::Up => self.scroll.offset
							[self.orientation as usize]
							.checked_sub(delta)
							.unwrap_or_default(),
						Direction::Right | Direction::Down => {
							self.scroll.offset[self.orientation as usize] + delta
						}
					};
					if let Some(index) = self
						.children
						.items
						.iter()
						.position(|x| x.offset >= min_offset)
					{
						self.children.focus = index;
						self.provoke_changed_property(WindowProperty::Focus);

						self.selection_changed();

						self.scroll.set_offset(
							self.orientation,
							self.children.items[self.children.focus].offset,
						);
						self.provoke_changed_property(WindowProperty::Children);
					}
				}
			},
		}
	}

	fn move_next(&mut self, scroll_only: bool) {
		match scroll_only {
			true => {
				if let Some(new_offset) = self
					.children
					.items
					.iter()
					.map(|x| x.offset)
					.find(|x| *x > self.scroll.offset[self.orientation as usize])
				{
					self.scroll.set_offset(self.orientation, new_offset);
					self.provoke_changed_property(WindowProperty::Children);
				}
			}
			false => {
				if self.children.focus < self.children.items.len() - 1 {
					if let Some(idx) = self.children.items[self.children.focus + 1..]
						.iter()
						.position(|x| x.rc.borrow_mut().is_enabled())
					{
						if !self.is_selection_visible() {
							self.make_selection_visible();
						}

						self.children.focus = self.children.focus + 1 + idx;
						self.provoke_changed_property(WindowProperty::Focus);

						self.selection_changed();

						if self.has_scroll_viewer() {
							let idx = self.orientation as usize;
							let max =
								self.scroll.offset[idx] + self.scroll.render_size[idx] as usize;
							let child = &self.children.items[self.children.focus];
							if child.offset >= max || child.offset + child.len >= max {
								let render_size =
									self.scroll.render_size[self.orientation as usize];
								if let Some(new_offset) =
									self.children.items.iter().map(|x| x.offset).find(|x| {
										x + render_size as usize >= child.offset + child.len
									}) {
									self.scroll.set_offset(self.orientation, new_offset);
									self.provoke_changed_property(WindowProperty::Children);
								}
							}
						}
					}
				}
			}
		}
	}

	fn move_previous(&mut self, scroll_only: bool) {
		match scroll_only {
			true => {
				if let Some(new_offset) = self
					.children
					.items
					.iter()
					.rev()
					.map(|x| x.offset)
					.find(|x| *x < self.scroll.offset[self.orientation as usize])
				{
					self.scroll.set_offset(self.orientation, new_offset);
					self.provoke_changed_property(WindowProperty::Children);
				}
			}
			false => {
				if self.children.focus > usize::MIN {
					if let Some(idx) = self.children.items[..self.children.focus]
						.iter()
						.rev()
						.position(|x| x.rc.borrow_mut().is_enabled())
					{
						if !self.is_selection_visible() {
							self.make_selection_visible();
						}

						self.children.focus = (self.children.focus - 1) - idx;
						self.provoke_changed_property(WindowProperty::Focus);

						self.selection_changed();

						if self.has_scroll_viewer() {
							let idx = self.orientation as usize;
							let min = self.scroll.offset[idx];
							let offset = self.children.items[self.children.focus].offset;
							if offset < min {
								self.scroll.set_offset(self.orientation, offset);
								self.provoke_changed_property(WindowProperty::Children);
							}
						}
					}
				}
			}
		}
	}

	pub fn has_scroll_viewer(&self) -> bool {
		self.scroll.scroll_viewer.strong_count() > usize::MIN
	}

	fn retrieve_children(&mut self, builder: &mut SubWindowBuilder) {
		let has_sv = self.has_scroll_viewer();
		let base_rect = builder.base_rect();
		self.scroll.viewport = Default::default();
		self.scroll.render_size = base_rect.size;

		let full_size = match self.orientation {
			Orientation::Horizontal => base_rect
				.size
				.x
				.checked_sub(self.children.items.len() as TSize - 1)
				.unwrap_or(base_rect.size.x),
			Orientation::Vertical => base_rect
				.size
				.y
				.checked_sub(self.children.items.len() as TSize - 1)
				.unwrap_or(base_rect.size.y),
		};
		let fixed_size = match full_size
			.checked_div(self.children.items.len() as TSize)
			.unwrap_or_default()
		{
			TSize::MIN => 1,
			v => v,
		};

		let item_count = self.children.items.len();

		match self.orientation {
			Orientation::Horizontal => {
				for (n, item) in self.children.items.iter_mut().enumerate() {
					let brw = item.rc.borrow();
					let tn = brw.border().thickness();
					let size = brw.desired_size(Vector2D::new(base_rect.size.x, base_rect.size.y));
					let len = match has_sv {
						true => size.x + tn.width(),
						false => fixed_size,
					} as usize;
					let start = match self.children.alignment {
						Alignment::LowerBound => TSize::MIN,
						Alignment::Center => (base_rect.size.y - size.y) / 2,
						Alignment::HigherBound => base_rect.size.y - size.y,
					};
					if self.scroll.viewport.x >= self.scroll.offset.x {
						match base_rect.subrect(
							(self.scroll.viewport.x - self.scroll.offset.x) as TSize,
							start,
							len as TSize,
							size.y,
						) {
							Ok(rect) => {
								builder.add_rect(rect).unwrap();
								builder.add_child(item.rc.clone());
							}
							Err(_) => {
								if !has_sv {
									self.scroll.viewport.x += len;
									break;
								}
							}
						}
					}
					item.offset = self.scroll.viewport.y;
					item.len = len;
					self.scroll.viewport.x += len;
					if n < item_count - 1 {
						self.scroll.viewport.x += self.margin as usize;
					}
				}
				self.scroll.viewport.y = base_rect.size.y as usize;
			}
			Orientation::Vertical => {
				for (n, item) in self.children.items.iter_mut().enumerate() {
					let brw = item.rc.borrow();
					let tn = brw.border().thickness();
					let size = brw.desired_size(Vector2D::new(base_rect.size.x, base_rect.size.y));
					let len = match has_sv {
						true => size.y + tn.height(),
						false => fixed_size,
					} as usize;
					let start = match self.children.alignment {
						Alignment::LowerBound => TSize::MIN,
						Alignment::Center => (base_rect.size.x - size.x) / 2,
						Alignment::HigherBound => base_rect.size.x - size.x,
					};
					if self.scroll.viewport.y >= self.scroll.offset.y {
						match base_rect.subrect(
							start,
							(self.scroll.viewport.y - self.scroll.offset.y) as TSize,
							size.x,
							len as TSize,
						) {
							Ok(rect) => {
								builder.add_rect(rect).unwrap();
								builder.add_child(item.rc.clone());
							}
							Err(_) => {
								if !has_sv {
									self.scroll.viewport.y += len;
									break;
								}
							}
						}
					}
					item.offset = self.scroll.viewport.y;
					item.len = len;
					self.scroll.viewport.y += len;
					//Skip margin for last item
					if n < item_count - 1 {
						self.scroll.viewport.y += self.margin as usize;
					}
				}
				self.scroll.viewport.x = base_rect.size.x as usize;
			}
		}
	}

	fn selection_changed(&mut self) {
		let cb = self.callback.clone();
		cb(self);
	}
}

impl Scrollable for Stackpanel {
	fn is_scrollable(&self, axis: Orientation) -> bool {
		self.scroll.is_scrollable(axis)
	}

	fn scroll(&mut self, direction: Direction, kind: ScrollKind) {
		self.scroll(direction, kind, false);
	}

	fn set_offset(&mut self, direction: Orientation, offset: usize) {
		self.scroll.set_offset(direction, offset);
	}

	fn offset(&self, axis: Orientation) -> usize {
		self.scroll.offset[axis as usize]
	}

	fn viewport(&self, axis: Orientation) -> usize {
		self.scroll.viewport[axis as usize]
	}

	fn set_scroll_viewer(&mut self, scroll_viewer: Weak<RefCell<ScrollViewer>>) {
		self.scroll.set_scroll_viewer(scroll_viewer);
		self.provoke_changed_property(WindowProperty::Children);
	}
}

impl ItemCollection<WindowRef> for Stackpanel {
	type Index = usize;

	/// Adds a child to the internal array
	fn add_item(&mut self, item: WindowRef) {
		self.children.items.push(Child::new(item));
		self.provoke_changed_property(WindowProperty::Children);
	}

	/// Removes a single child from the internal array
	fn remove_item(&mut self, item: &WindowRef) {
		let uid = item.borrow().uid();
		if let Some(index) = self
			.children
			.items
			.iter()
			.position(|x| x.rc.borrow().uid() == uid)
		{
			self.children.items.remove(index);
			if self.children.focus == index {
				self.children.focus = usize::MIN;
				self.selection_changed();
				self.provoke_changed_property(WindowProperty::Focus);
			}
			self.provoke_changed_property(WindowProperty::Children);
		}
	}

	fn remove_at(&mut self, index: Self::Index) -> WindowRef {
		self.children.items.remove(index).rc
	}

	/// Returns a child by its index
	fn get_item(&mut self, index: Self::Index) -> Option<&WindowRef> {
		match self.children.items.get(index) {
			Some(item) => Some(&item.rc),
			None => None,
		}
	}

	/// Removes all children from the internal array
	fn clear_items(&mut self) {
		if !self.children.items.is_empty() {
			self.children.items.clear();
			self.provoke_changed_property(WindowProperty::Children);
			self.provoke_changed_property(WindowProperty::Focus);
			self.selection_changed();
		}
	}

	/// Returns the number of children
	fn items(&self) -> Self::Index {
		self.children.items.len()
	}
}

impl Window for Stackpanel {
	fn render(&self, canvas: &mut Canvas) {
		if let Some(color) = self.base.colors.disabled
			&& !self.base.enabled
		{
			canvas.fill_foreground(color);
		}
	}

	fn children(&mut self, mut builder: SubWindowBuilder) -> SubWindows {
		if self.children.items.is_empty() {
			return SubWindows::default();
		}

		builder.disable_overlapping();
		self.retrieve_children(&mut builder);
		builder.build().unwrap()
	}

	fn handle_event(&mut self, event: &mut WindowEvent) {
		(self.key_handler)(self, event);
	}

	fn focus(&self) -> Option<WindowRef> {
		match self.base.enabled {
			true => self
				.children
				.items
				.get(self.children.focus)
				.cloned()
				.map(|x| x.rc),
			false => None,
		}
	}

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

impl WindowLayout for Stackpanel {
	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 HasWindowUID for Stackpanel {
	fn uid(&self) -> WindowUID {
		self.base.uid
	}
}

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

	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 Stackpanel {
	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;
	}
}