rat-widget 3.0.2

//! Render tabs.
//!
//! This widget doesn't render the content.
//! Use [TabbedState::widget_area] to render the selected tab.
//!
//! ```
//! use ratatui_core::buffer::Buffer;
//! use ratatui_core::layout::Rect;
//! use ratatui_core::text::Text;
//! use ratatui_core::widgets::{StatefulWidget, Widget};
//! use ratatui_widgets::block::{Block};
//! use rat_widget::tabbed::{TabPlacement, TabType, Tabbed, TabbedState};
//! # struct State { tabbed: TabbedState }
//! # let mut state = State { tabbed: Default::default() };
//! # let mut buf = Buffer::default();
//! # let buf = &mut buf;
//! # let area = Rect::default();
//!
//! let mut tab = Tabbed::new()
//!     .tab_type(TabType::Attached)
//!     .placement(TabPlacement::Top)
//!     .closeable(true)
//!     .block(
//!          Block::bordered()
//!     )
//!     .tabs(["Issues", "Numbers", "More numbers"])
//!     .render(area, buf, &mut state.tabbed);
//!
//! match state.tabbed.selected() {
//!     Some(0) => {
//!         Text::from("... issues ...")
//!             .render(state.tabbed.widget_area, buf);
//!     }
//!     Some(1) => {
//!         Text::from("... 1,2,3,4 ...")
//!             .render(state.tabbed.widget_area, buf);
//!     }
//!     Some(1) => {
//!         Text::from("... 5,6,7,8 ...")
//!             .render(state.tabbed.widget_area, buf);
//!     }
//!     _ => {}
//! }
//!
//! ```
//!

use crate::_private::NonExhaustive;
use crate::event::TabbedOutcome;
use crate::tabbed::attached::AttachedTabs;
use crate::tabbed::glued::GluedTabs;
use crate::util::union_all_non_empty;
use rat_event::util::MouseFlagsN;
use rat_event::{HandleEvent, MouseOnly, Regular, ct_event, event_flow};
use rat_focus::{FocusBuilder, FocusFlag, HasFocus, Navigation};
use rat_reloc::{RelocatableState, relocate_area, relocate_areas};
use ratatui_core::buffer::Buffer;
use ratatui_core::layout::Rect;
use ratatui_core::style::Style;
use ratatui_core::text::Line;
use ratatui_core::widgets::StatefulWidget;
use ratatui_crossterm::crossterm::event::Event;
use ratatui_widgets::block::Block;
use std::cmp::min;
use std::fmt::Debug;
use std::rc::Rc;

mod attached;
pub(crate) mod event;
mod glued;

/// Placement relative to the Rect given to render.
///
/// The popup-menu is always rendered outside the box,
/// and this gives the relative placement.
#[derive(Debug, Default, Clone, Copy, PartialEq, Eq)]
pub enum TabPlacement {
    /// On top of the given area. Placed slightly left, so that
    /// the menu text aligns with the left border.
    #[default]
    Top,
    /// Placed left-top of the given area.
    /// For a submenu opening to the left.
    Left,
    /// Placed right-top of the given area.
    /// For a submenu opening to the right.
    Right,
    /// Below the bottom of the given area. Placed slightly left,
    /// so that the menu text aligns with the left border.
    Bottom,
}

/// Rendering style for the tabs.
#[derive(Debug, Default, Clone, Copy, PartialEq, Eq)]
#[non_exhaustive]
pub enum TabType {
    /// Basic tabs glued to the outside of the widget.
    Glued,

    /// Embedded tabs in the Block.
    ///
    /// If no block has been set, this will draw a block at the side
    /// of the tabs.
    ///
    /// On the left/right side this will just draw a link to the tab-text.
    /// On the top/bottom side the tabs will be embedded in the border.
    #[default]
    Attached,
}

/// A tabbed widget.
///
/// This widget draws the tabs and handles events.
///
/// Use [TabbedState::selected] and [TabbedState::widget_area] to render
/// the actual content of the tab.
///
#[derive(Debug, Default, Clone)]
pub struct Tabbed<'a> {
    tab_type: TabType,
    placement: TabPlacement,
    closeable: bool,
    tabs: Vec<Line<'a>>,

    style: Style,
    block: Option<Block<'a>>,
    tab_style: Option<Style>,
    hover_style: Option<Style>,
    select_style: Option<Style>,
    focus_style: Option<Style>,
}

/// Widget for the Layout of the tabs.
#[derive(Debug, Clone)]
pub struct LayoutWidget<'a> {
    tab: Rc<Tabbed<'a>>,
}

/// Primary widget for rendering the Tabbed.
#[derive(Debug, Clone)]
pub struct TabbedWidget<'a> {
    tab: Rc<Tabbed<'a>>,
}

/// Combined Styles
#[derive(Debug, Clone)]
pub struct TabbedStyle {
    pub style: Style,
    pub block: Option<Block<'static>>,
    pub border_style: Option<Style>,
    pub title_style: Option<Style>,
    pub tab: Option<Style>,
    pub hover: Option<Style>,
    pub select: Option<Style>,
    pub focus: Option<Style>,

    pub tab_type: Option<TabType>,
    pub placement: Option<TabPlacement>,

    pub non_exhaustive: NonExhaustive,
}

/// State & event-handling.
#[derive(Debug)]
pub struct TabbedState {
    /// Total area.
    /// __readonly__. renewed for each render.
    pub area: Rect,
    /// Area for drawing the Block inside the tabs.
    /// __readonly__. renewed for each render.
    pub block_area: Rect,
    /// Area used to render the content of the tab.
    /// Use this area to render the current tab content.
    /// __readonly__. renewed for each render.
    pub widget_area: Rect,

    /// Total area reserved for tabs.
    /// __readonly__. renewed for each render.
    pub tab_title_area: Rect,
    /// Area of each tab.
    /// __readonly__. renewed for each render.
    pub tab_title_areas: Vec<Rect>,
    /// Area for 'Close Tab' interaction.
    /// __readonly__. renewed for each render.
    pub tab_title_close_areas: Vec<Rect>,

    /// Selected Tab, only ever is None if there are no tabs.
    /// Otherwise, set to 0 on render.
    /// __read+write___
    pub selected: Option<usize>,

    /// Focus
    /// __read+write__
    pub focus: FocusFlag,
    /// Mouse flags
    /// __read+write__
    pub mouse: MouseFlagsN,

    /// Rendering is split into base-widget and menu-popup.
    /// Relocate after rendering the popup.
    relocate_popup: bool,

    pub non_exhaustive: NonExhaustive,
}

impl<'a> Tabbed<'a> {
    pub fn new() -> Self {
        Self::default()
    }

    /// Tab type.
    pub fn tab_type(mut self, tab_type: TabType) -> Self {
        self.tab_type = tab_type;
        self
    }

    /// Tab placement.
    pub fn placement(mut self, placement: TabPlacement) -> Self {
        self.placement = placement;
        self
    }

    /// Tab-text.
    pub fn tabs(mut self, tabs: impl IntoIterator<Item = impl Into<Line<'a>>>) -> Self {
        self.tabs = tabs.into_iter().map(|v| v.into()).collect::<Vec<_>>();
        self
    }

    /// Closeable tabs?
    ///
    /// Renders a close symbol and reacts with [TabbedOutcome::Close].
    pub fn closeable(mut self, closeable: bool) -> Self {
        self.closeable = closeable;
        self
    }

    /// Block
    pub fn block(mut self, block: Block<'a>) -> Self {
        self.block = Some(block);
        self
    }

    /// Set combined styles.
    pub fn styles(mut self, styles: TabbedStyle) -> Self {
        self.style = styles.style;
        if styles.block.is_some() {
            self.block = styles.block;
        }
        if let Some(border_style) = styles.border_style {
            self.block = self.block.map(|v| v.border_style(border_style));
        }
        if let Some(title_style) = styles.title_style {
            self.block = self.block.map(|v| v.title_style(title_style));
        }
        self.block = self.block.map(|v| v.style(self.style));

        if styles.tab.is_some() {
            self.tab_style = styles.tab;
        }
        if styles.select.is_some() {
            self.select_style = styles.select;
        }
        if styles.hover.is_some() {
            self.hover_style = styles.hover;
        }
        if styles.focus.is_some() {
            self.focus_style = styles.focus;
        }
        if let Some(tab_type) = styles.tab_type {
            self.tab_type = tab_type;
        }
        if let Some(placement) = styles.placement {
            self.placement = placement
        }
        self
    }

    /// Base style. Mostly for any background.
    pub fn style(mut self, style: Style) -> Self {
        self.style = style;
        self.block = self.block.map(|v| v.style(style));
        self
    }

    /// Style for the tab-text.
    pub fn tab_style(mut self, style: Style) -> Self {
        self.tab_style = Some(style);
        self
    }

    /// Style for hover.
    pub fn hover_style(mut self, style: Style) -> Self {
        self.hover_style = Some(style);
        self
    }

    /// Style for the selected tab.
    pub fn select_style(mut self, style: Style) -> Self {
        self.select_style = Some(style);
        self
    }

    /// Style for a focused tab.
    pub fn focus_style(mut self, style: Style) -> Self {
        self.focus_style = Some(style);
        self
    }

    /// Constructs the widgets for rendering.
    ///
    /// Returns the LayoutWidget that must run first. It
    /// doesn't actually render anything, it just calculates
    /// the layout for the tab regions.
    ///
    /// Use [TabbedState::widget_area] to render the selected tab.
    ///
    /// The TabbedWidget actually renders the tabs.
    /// Render it after you finished with the content.
    pub fn into_widgets(self) -> (LayoutWidget<'a>, TabbedWidget<'a>) {
        let rc = Rc::new(self);
        (
            LayoutWidget {
                tab: rc.clone(), //
            },
            TabbedWidget {
                tab:rc, //
            },
        )
    }
}

impl Default for TabbedStyle {
    fn default() -> Self {
        Self {
            style: Default::default(),
            tab: None,
            hover: None,
            select: None,
            focus: None,
            tab_type: None,
            placement: None,
            block: None,
            border_style: None,
            title_style: None,
            non_exhaustive: NonExhaustive,
        }
    }
}

impl StatefulWidget for &Tabbed<'_> {
    type State = TabbedState;

    fn render(self, area: Rect, buf: &mut Buffer, state: &mut Self::State) {
        layout(self, area, state);
        render(self, buf, state);
        state.relocate_popup = false;
    }
}

impl StatefulWidget for Tabbed<'_> {
    type State = TabbedState;

    fn render(self, area: Rect, buf: &mut Buffer, state: &mut Self::State) {
        layout(&self, area, state);
        render(&self, buf, state);
        state.relocate_popup = false;
    }
}

impl<'a> StatefulWidget for &LayoutWidget<'a> {
    type State = TabbedState;

    fn render(self, area: Rect, _buf: &mut Buffer, state: &mut Self::State) {
        layout(self.tab.as_ref(), area, state);
    }
}

impl<'a> StatefulWidget for LayoutWidget<'a> {
    type State = TabbedState;

    fn render(self, area: Rect, _buf: &mut Buffer, state: &mut Self::State) {
        layout(self.tab.as_ref(), area, state);
    }
}

fn layout(tabbed: &Tabbed<'_>, area: Rect, state: &mut TabbedState) {
    state.relocate_popup = true;
    if tabbed.tabs.is_empty() {
        state.selected = None;
    } else {
        if state.selected.is_none() {
            state.selected = Some(0);
        }
    }

    match tabbed.tab_type {
        TabType::Glued => {
            GluedTabs.layout(area, tabbed, state);
        }
        TabType::Attached => {
            AttachedTabs.layout(area, tabbed, state);
        }
    }
}

impl<'a> StatefulWidget for &TabbedWidget<'a> {
    type State = TabbedState;

    fn render(self, _area: Rect, buf: &mut Buffer, state: &mut Self::State) {
        render(self.tab.as_ref(), buf, state);
    }
}

impl<'a> StatefulWidget for TabbedWidget<'a> {
    type State = TabbedState;

    fn render(self, _area: Rect, buf: &mut Buffer, state: &mut Self::State) {
        render(self.tab.as_ref(), buf, state);
    }
}

fn render(tabbed: &Tabbed<'_>, buf: &mut Buffer, state: &mut TabbedState) {
    if tabbed.tabs.is_empty() {
        state.selected = None;
    } else {
        if state.selected.is_none() {
            state.selected = Some(0);
        }
    }

    match tabbed.tab_type {
        TabType::Glued => {
            GluedTabs.render(buf, tabbed, state);
        }
        TabType::Attached => {
            AttachedTabs.render(buf, tabbed, state);
        }
    }
}

impl Default for TabbedState {
    fn default() -> Self {
        Self {
            area: Default::default(),
            block_area: Default::default(),
            widget_area: Default::default(),
            tab_title_area: Default::default(),
            tab_title_areas: Default::default(),
            tab_title_close_areas: Default::default(),
            selected: Default::default(),
            focus: Default::default(),
            mouse: Default::default(),
            relocate_popup: Default::default(),
            non_exhaustive: NonExhaustive,
        }
    }
}

impl Clone for TabbedState {
    fn clone(&self) -> Self {
        Self {
            area: self.area,
            block_area: self.block_area,
            widget_area: self.widget_area,
            tab_title_area: self.tab_title_area,
            tab_title_areas: self.tab_title_areas.clone(),
            tab_title_close_areas: self.tab_title_close_areas.clone(),
            selected: self.selected,
            focus: self.focus.new_instance(),
            mouse: Default::default(),
            relocate_popup: self.relocate_popup,
            non_exhaustive: NonExhaustive,
        }
    }
}

impl HasFocus for TabbedState {
    fn build(&self, builder: &mut FocusBuilder) {
        builder.leaf_widget(self);
    }

    fn build_nav(&self, navigable: Navigation, builder: &mut FocusBuilder) {
        if !matches!(navigable, Navigation::None | Navigation::Leave) {
            builder.widget_with_flags(
                self.focus(),
                union_all_non_empty(&self.tab_title_areas),
                self.area_z(),
                navigable,
            );
        } else {
            self.build(builder);
        }
    }

    fn focus(&self) -> FocusFlag {
        self.focus.clone()
    }

    fn area(&self) -> Rect {
        Rect::default()
    }

    fn navigable(&self) -> Navigation {
        Navigation::Leave
    }
}

impl RelocatableState for TabbedState {
    fn relocate(&mut self, shift: (i16, i16), clip: Rect) {
        if !self.relocate_popup {
            self.area = relocate_area(self.area, shift, clip);
            self.block_area = relocate_area(self.block_area, shift, clip);
            self.widget_area = relocate_area(self.widget_area, shift, clip);
            self.tab_title_area = relocate_area(self.tab_title_area, shift, clip);
            relocate_areas(self.tab_title_areas.as_mut(), shift, clip);
            relocate_areas(self.tab_title_close_areas.as_mut(), shift, clip);
        }
    }

    fn relocate_popup(&mut self, shift: (i16, i16), clip: Rect) {
        if self.relocate_popup {
            self.relocate_popup = false;
            self.area = relocate_area(self.area, shift, clip);
            self.block_area = relocate_area(self.block_area, shift, clip);
            self.widget_area = relocate_area(self.widget_area, shift, clip);
            self.tab_title_area = relocate_area(self.tab_title_area, shift, clip);
            relocate_areas(self.tab_title_areas.as_mut(), shift, clip);
            relocate_areas(self.tab_title_close_areas.as_mut(), shift, clip);
        }
    }
}

impl TabbedState {
    /// New initial state.
    pub fn new() -> Self {
        Default::default()
    }

    /// State with a focus name.
    pub fn named(name: &str) -> Self {
        let mut z = Self::default();
        z.focus = z.focus.with_name(name);
        z
    }

    pub fn selected(&self) -> Option<usize> {
        self.selected
    }

    pub fn select(&mut self, selected: Option<usize>) {
        self.selected = selected;
    }

    /// Selects the next tab. Stops at the end.
    pub fn next_tab(&mut self) -> bool {
        let old_selected = self.selected;

        if let Some(selected) = self.selected() {
            self.selected = Some(min(
                selected + 1,
                self.tab_title_areas.len().saturating_sub(1),
            ));
        }

        old_selected != self.selected
    }

    /// Selects the previous tab. Stops at the end.
    pub fn prev_tab(&mut self) -> bool {
        let old_selected = self.selected;

        if let Some(selected) = self.selected() {
            if selected > 0 {
                self.selected = Some(selected - 1);
            }
        }

        old_selected != self.selected
    }
}

/// Handle the regular events for Tabbed.
impl HandleEvent<Event, Regular, TabbedOutcome> for TabbedState {
    fn handle(&mut self, event: &Event, _qualifier: Regular) -> TabbedOutcome {
        if self.is_focused() {
            event_flow!(
                return match event {
                    ct_event!(keycode press Left) => self.prev_tab().into(),
                    ct_event!(keycode press Right) => self.next_tab().into(),
                    ct_event!(keycode press Up) => self.prev_tab().into(),
                    ct_event!(keycode press Down) => self.next_tab().into(),
                    _ => TabbedOutcome::Continue,
                }
            );
        }

        self.handle(event, MouseOnly)
    }
}

impl HandleEvent<Event, MouseOnly, TabbedOutcome> for TabbedState {
    fn handle(&mut self, event: &Event, _qualifier: MouseOnly) -> TabbedOutcome {
        match event {
            ct_event!(mouse any for e) if self.mouse.hover(&self.tab_title_close_areas, e) => {
                TabbedOutcome::Changed
            }
            ct_event!(mouse any for e) if self.mouse.drag(&[self.tab_title_area], e) => {
                if let Some(n) = self.mouse.item_at(&self.tab_title_areas, e.column, e.row) {
                    self.select(Some(n));
                    TabbedOutcome::Select(n)
                } else {
                    TabbedOutcome::Unchanged
                }
            }
            ct_event!(mouse down Left for x, y)
                if self.tab_title_area.contains((*x, *y).into()) =>
            {
                if let Some(sel) = self.mouse.item_at(&self.tab_title_close_areas, *x, *y) {
                    TabbedOutcome::Close(sel)
                } else if let Some(sel) = self.mouse.item_at(&self.tab_title_areas, *x, *y) {
                    self.select(Some(sel));
                    TabbedOutcome::Select(sel)
                } else {
                    TabbedOutcome::Continue
                }
            }

            _ => TabbedOutcome::Continue,
        }
    }
}

/// The design space for tabs is too big to capture with a handful of parameters.
///
/// This trait splits off the layout and rendering of the actual tabs from
/// the general properties and behaviour of tabs.
trait TabWidget: Debug {
    /// Calculate the layout for the tabs.
    fn layout(
        &self, //
        area: Rect,
        tabbed: &Tabbed<'_>,
        state: &mut TabbedState,
    );

    /// Render the tabs.
    fn render(
        &self, //
        buf: &mut Buffer,
        tabbed: &Tabbed<'_>,
        state: &mut TabbedState,
    );
}

/// Handle all events.
/// Text events are only processed if focus is true.
/// Mouse events are processed if they are in range.
pub fn handle_events(state: &mut TabbedState, focus: bool, event: &Event) -> TabbedOutcome {
    state.focus.set(focus);
    HandleEvent::handle(state, event, Regular)
}

/// Handle only mouse-events.
pub fn handle_mouse_events(state: &mut TabbedState, event: &Event) -> TabbedOutcome {
    HandleEvent::handle(state, event, MouseOnly)
}