termscp/src/ui/layout/components/file_list.rs

//! ## FileList
//!
//! `FileList` component renders a file list tab

/*
*
*   Copyright (C) 2020-2021 Christian Visintin - christian.visintin1997@gmail.com
*
* 	This file is part of "TermSCP"
*
*   TermSCP is free software: you can redistribute it and/or modify
*   it under the terms of the GNU General Public License as published by
*   the Free Software Foundation, either version 3 of the License, or
*   (at your option) any later version.
*
*   TermSCP is distributed in the hope that it will be useful,
*   but WITHOUT ANY WARRANTY; without even the implied warranty of
*   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
*   GNU General Public License for more details.
*
*   You should have received a copy of the GNU General Public License
*   along with TermSCP.  If not, see <http://www.gnu.org/licenses/>.
*
*/

// locals
use super::{Component, InputEvent, Msg, Payload, Props, PropsBuilder, Render, States};
// ext
use crossterm::event::KeyCode;
use tui::{
    layout::Corner,
    style::{Color, Style},
    text::Span,
    widgets::{Block, Borders, List, ListItem},
};

// -- states

/// ## OwnStates
///
/// OwnStates contains states for this component
#[derive(Clone)]
struct OwnStates {
    list_index: usize, // Index of selected element in list
    list_len: usize,   // Length of file list
}

impl Default for OwnStates {
    fn default() -> Self {
        OwnStates {
            list_index: 0,
            list_len: 0,
        }
    }
}

impl OwnStates {
    /// ### set_list_len
    ///
    /// Set list length
    pub fn set_list_len(&mut self, len: usize) {
        self.list_len = len;
    }

    /// ### get_list_index
    ///
    /// Return current value for list index
    pub fn get_list_index(&self) -> usize {
        self.list_index
    }

    /// ### incr_list_index
    ///
    /// Incremenet list index
    pub fn incr_list_index(&mut self) {
        // Check if index is at last element
        if self.list_len + 1 < self.list_len {
            self.list_len += 1;
        }
    }

    /// ### decr_list_index
    ///
    /// Decrement list index
    pub fn decr_list_index(&mut self) {
        // Check if index is bigger than 0
        if self.list_len > 0 {
            self.list_len -= 1;
        }
    }

    /// ### reset_list_index
    ///
    /// Reset list index to 0
    pub fn reset_list_index(&mut self) {
        self.list_len = 0;
    }
}

impl States for OwnStates {}

// -- Component

/// ## FileList
///
/// File list component
pub struct FileList {
    props: Props,
    states: OwnStates,
}

impl FileList {
    /// ### new
    ///
    /// Instantiates a new FileList starting from Props
    /// The method also initializes the component states.
    pub fn new(props: Props) -> Self {
        // Initialize states
        let mut states: OwnStates = OwnStates::default();
        // Set list length
        states.set_list_len(match &props.texts.body {
            Some(tokens) => tokens.len(),
            None => 0,
        });
        FileList { props, states }
    }
}

impl Component for FileList {
    /// ### render
    ///
    /// Based on the current properties and states, return a Widget instance for the Component
    /// Returns None if the component is hidden
    fn render(&self) -> Option<Render> {
        match self.props.visible {
            false => None,
            true => {
                // Make list
                let list_item: Vec<ListItem> = match self.props.texts.body.as_ref() {
                    None => vec![],
                    Some(lines) => lines
                        .iter()
                        .map(|line: &String| ListItem::new(Span::from(line.to_string())))
                        .collect(),
                };
                let (fg, bg): (Color, Color) = match self.props.focus {
                    true => (Color::Reset, self.props.background),
                    false => (self.props.foreground, Color::Reset),
                };
                let title: String = match self.props.texts.title.as_ref() {
                    Some(t) => t.clone(),
                    None => String::new(),
                };
                // Render
                Some(Render {
                    widget: Box::new(
                        List::new(list_item)
                            .block(
                                Block::default()
                                    .borders(Borders::ALL)
                                    .border_style(match self.props.focus {
                                        true => Style::default().fg(self.props.foreground),
                                        false => Style::default(),
                                    })
                                    .title(title),
                            )
                            .start_corner(Corner::TopLeft)
                            .highlight_style(
                                Style::default()
                                    .bg(bg)
                                    .fg(fg)
                                    .add_modifier(self.props.get_modifiers()),
                            ),
                    ),
                    value: self.get_value(),
                })
            }
        }
    }

    /// ### update
    ///
    /// Update component properties
    /// Properties should first be retrieved through `get_props` which creates a builder from
    /// existing properties and then edited before calling update
    fn update(&mut self, props: Props) -> Msg {
        self.props = props;
        // re-Set list length
        self.states.set_list_len(match &self.props.texts.body {
            Some(tokens) => tokens.len(),
            None => 0,
        });
        // Reset list index
        self.states.reset_list_index();
        Msg::None
    }

    /// ### get_props
    ///
    /// Returns a props builder starting from component properties.
    /// This returns a prop builder in order to make easier to create
    /// new properties for the element.
    fn get_props(&self) -> PropsBuilder {
        PropsBuilder::from_props(&self.props)
    }

    /// ### on
    ///
    /// Handle input event and update internal states
    fn on(&mut self, ev: InputEvent) -> Msg {
        // Match event
        if let InputEvent::Key(key) = ev {
            match key.code {
                KeyCode::Down => {
                    // Update states
                    self.states.incr_list_index();
                    Msg::None
                }
                KeyCode::Up => {
                    // Update states
                    self.states.decr_list_index();
                    Msg::None
                }
                KeyCode::PageDown => {
                    // Update states
                    for _ in 0..8 {
                        self.states.incr_list_index();
                    }
                    Msg::None
                }
                KeyCode::PageUp => {
                    // Update states
                    for _ in 0..8 {
                        self.states.decr_list_index();
                    }
                    Msg::None
                }
                KeyCode::Enter => {
                    // Report event
                    Msg::OnSubmit(Payload::Unumber(self.states.get_list_index()))
                }
                _ => {
                    // Return key event to activity
                    Msg::OnKey(key)
                }
            }
        } else {
            // Unhandled event
            Msg::None
        }
    }

    /// ### get_value
    /// 
    /// Return component value
    fn get_value(&self) -> Payload {
        Payload::Unumber(self.states.get_list_index())
    }

    // -- events

    /// ### should_umount
    ///
    /// The component must provide to the supervisor whether it should be umounted (destroyed)
    /// This makes sense to be called after an `on` or after an `update`, where the states changes.
    fn should_umount(&self) -> bool {
        // Never true
        false
    }
}