flux-tui 0.5.0

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

use std::num::NonZero;
use std::rc::Rc;
use std::time::{Duration, Instant};

use crossterm::event::KeyCode;
use unicode_segmentation::UnicodeSegmentation;
use unicode_width::*;


pub type TextChangedCallback = dyn Fn(&mut Textbox);
pub type TextboxKeyHandler = fn(&mut Textbox, event: &mut WindowEvent);

/// Single-line text input method
/// Allows navigating through the string, removing (using Backspace) and adding characters at the '_' sign
/// The cursor will hide the grapheme behind it
///
/// Design (including Border):
/// ```text
/// ┌─────┐
/// │Tex_1│
/// └─────┘
/// ```
pub struct Textbox {
	text: String,
	grapheme_count: usize,
	cursor: usize,
	offset: usize,
	has_focus: bool,
	// Actual current size of the component
	width: usize,
	max_length: usize,
	base: WidgetBase,
	readonly: bool,

	focus_color: Option<Color>,
	fat_cursor: bool,

	last_change: Instant,
	delay: Duration,
	callback: Rc<TextChangedCallback>,
	key_handler: TextboxKeyHandler,
}

impl Default for Textbox {
	fn default() -> Self {
		let mut s = Self {
			text: String::new(),
			width: usize::MIN,
			max_length: 128,
			base: WidgetBase::default(),
			has_focus: false,
			cursor: usize::MIN,
			offset: usize::MIN,
			grapheme_count: usize::MIN,
			readonly: false,

			focus_color: None,
			fat_cursor: true,

			last_change: Instant::now(),
			delay: Self::DELAY_DEFAULT,
			callback: Rc::new(Self::default_callback),
			key_handler: Self::default_key_handler,
		};
		s.base.constraints.y.min = NonZero::<TSize>::MIN;
		s.base.constraints.y.max = Size::Fixed(NonZero::<TSize>::MIN);
		s
	}
}

impl Textbox {
	pub const DELAY_DEFAULT: Duration = Duration::from_millis(250);
	pub const CURSOR: Grapheme = Grapheme::new_unchecked("_", GlyphWidth::Half);
	pub const CURSOR_WIDE: Grapheme = Grapheme::new_unchecked("＿", GlyphWidth::Half);

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

	pub fn default_key_handler(&mut self, event: &mut WindowEvent) {
		if let Event::Key(k) = event.raw() {
			match k.code {
				KeyCode::Left => {
					self.move_cursor_left();
					event.handled = true;
				}
				KeyCode::Right => {
					self.move_cursor_right();
					event.handled = true;
				}
				KeyCode::Backspace => {
					if !self.readonly {
						self.remove_glyph_before_cursor();
					}
					event.handled = true;
				}
				KeyCode::Char(ch) => {
					if !self.readonly {
						self.insert_char_at_cursor(ch);
					}
					event.handled = true;
				}
				_ => {}
			}
		}
	}

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

	pub fn set_callback_delay(&mut self, duration: Duration) {
		self.delay = duration;
	}

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

	/// `fat_cursor`: `true` will just highlight the current position, `false` will use _ instead
	/// as cursor
	pub fn set_cursor_type(&mut self, fat_cursor: bool) {
		self.fat_cursor = fat_cursor;
	}

	/// Foreground color when the textbox has focus
	pub fn set_focus_color(&mut self, focus_color: Option<Color>) {
		self.focus_color = focus_color;
	}

	pub fn is_readonly(&self) -> bool {
		self.readonly
	}

	pub fn set_readonly(&mut self, readonly: bool) {
		self.readonly = readonly;
	}

	/// Returns the maximum length of the inner text
	pub fn get_max_length(&self) -> usize {
		self.max_length
	}

	/// Sets the maximum length of the inner text (number of graphemes)
	pub fn set_max_length(&mut self, length: usize) {
		self.max_length = length;
	}

	/// Returns the inner text
	pub fn get_text(&self) -> &str {
		&self.text
	}

	/// Updates the inner text
	pub fn set_text(&mut self, text: &str) {
		self.text.clear();
		self.text.push_str(text);
		self.grapheme_count = self.text.graphemes(true).count();

		self.cursor = self.grapheme_count % self.width;
		self.offset = self.grapheme_count - self.cursor;

		self.text_changed();
	}

	/// Clears the inner text
	pub fn clear(&mut self) {
		self.text.clear();
		self.grapheme_count = usize::MIN;
		self.cursor = usize::MIN;
		self.offset = usize::MIN;
		self.text_changed();
	}

	pub fn move_cursor_left(&mut self) {
		if self.actual_cursor_pos() > usize::MIN {
			self.decrease_cursor();
		}
	}

	pub fn move_cursor_right(&mut self) {
		if self.actual_cursor_pos() < self.grapheme_count {
			self.increase_cursor();
			self.check_cursor();
		}
	}

	pub fn remove_glyph_before_cursor(&mut self) {
		let cursor = self.actual_cursor_pos();
		if cursor > usize::MIN {
			let mut iter = self.text.grapheme_indices(true).skip(cursor - 1);
			if let Some((idx, str)) = iter.next() {
				(0..str.chars().count()).for_each(|_| {
					self.text.remove(idx);
				});
				self.decrease_cursor();
			}
			self.grapheme_count = self.text.graphemes(true).count();
		}
	}

	pub fn insert_char_at_cursor(&mut self, ch: char) {
		let cursor = self.actual_cursor_pos();
		// Do nothing if its a control character
		let ch_width = match ch.width() {
			Some(w) => w,
			None => return,
		};

		if self.grapheme_count < self.max_length {
			if cursor == self.grapheme_count {
				if self.get_current_visible_width() == self.width - ch_width {
					self.cursor -= 1;
					self.offset += 1;
				}
				self.cursor += 1;
			}
			else {
				self.increase_cursor();
			}

			let mut iter = self.text.grapheme_indices(true).skip(cursor);
			match iter.next().map(|(idx, _)| idx) {
				Some(idx) => self.text.insert(idx, ch),
				None => self.text.push(ch),
			}
			self.grapheme_count = self.text.graphemes(true).count();
			self.check_cursor();
			self.text_changed();
		}
	}

	fn check_cursor(&mut self) {
		// Prevent issues with grapheme clusters
		let len = self.text.width();
		if self.actual_cursor_pos() > len {
			let diff = self.actual_cursor_pos() - len;
			self.cursor -= diff;
		}
	}

	fn actual_cursor_pos(&self) -> usize {
		self.cursor + self.offset
	}

	fn get_current_visible_width(&self) -> usize {
		let mut iter = self.text.grapheme_indices(true).skip(self.offset);
		let start = iter.next().map(|x| x.0).unwrap_or(usize::MIN);
		let mut iter = self
			.text
			.grapheme_indices(true)
			.skip(self.offset + self.cursor + 1);
		let end = iter.next().map(|x| x.0).unwrap_or(self.text.len());
		self.text[start..end].width()
	}

	fn is_cursor_at_max_width(&self) -> bool {
		self.get_current_visible_width() == self.width
	}

	fn increase_cursor(&mut self) {
		if self.is_cursor_at_max_width() {
			self.offset += 1;
		}
		else {
			self.cursor += 1;
		}
	}

	fn decrease_cursor(&mut self) {
		if self.offset > usize::MIN && self.cursor == usize::MIN {
			self.offset -= 1;
		}
		else {
			self.cursor -= 1;
		}
	}

	fn text_changed(&mut self) {
		if self.last_change.elapsed() > self.delay {
			let cb = self.callback.clone();
			cb(self);
		}

		self.last_change = Instant::now();
	}
}

impl Window for Textbox {
	fn render(&self, canvas: &mut Canvas) {
		let mut row = canvas.get_row_variable_width(TSize::MIN).unwrap();
		let mut graphemes = self.text.graphemes(true).skip(self.offset);
		let mut counter = usize::MIN;
		while row.cursor() < row.width() {
			let gr = graphemes.next();
			let str;
			let mut style = Style::None;
			let mut fg = None;

			if !self.base.enabled {
				fg = self.base.colors.disabled;
			}
			else if self.has_focus {
				fg = self.focus_color;
			}

			fg = fg.or(self.base.colors.base_fg);

			if self.has_focus && counter == self.cursor {
				if self.fat_cursor {
					str = gr
						.map(|v| Grapheme::from(v).unwrap())
						.unwrap_or(Grapheme::PLACEHOLDER);
					style = Style::Reverse | Style::ResetAfter;
				}
				else {
					let width = gr.map(|x| x.width()).unwrap_or(usize::MIN);
					str = match width {
						2 => Self::CURSOR_WIDE,
						_ => Self::CURSOR,
					};
				}
			}
			else {
				str = gr
					.map(|v| Grapheme::from(v).unwrap())
					.unwrap_or(Grapheme::PLACEHOLDER);
			}
			row.add_grapheme(str, fg, self.base.colors.base_bg, style)
				.ok();
			counter += 1;
		}
	}

	fn handle_event(&mut self, event: &mut WindowEvent) {
		match event.raw() {
			Event::Resize(w, _) => self.width = *w as usize,
			Event::FocusGained => self.has_focus = true,
			Event::FocusLost => self.has_focus = false,
			_ => (self.key_handler)(self, event),
		}
	}

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

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

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

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

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

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

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

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

	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, _: 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_enabled_state(&mut self, is_enabled: bool) {
		self.base.enabled = is_enabled;
	}

	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, _: SizeConstraint) {}
}

impl WidgetColors for Textbox {
	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;
	}
}