// This file is part of Deja-vu.
//
// Deja-vu 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.
//
// Deja-vu 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 Deja-vu. If not, see <https://www.gnu.org/licenses/>.
//
use color_eyre::Result;
use crossterm::event::KeyEvent;
use ratatui::{prelude::*, widgets::*};
use tokio::sync::mpsc::UnboundedSender;

use super::{state::StatefulList, Component};
use crate::{action::Action, app::Mode, config::Config, system::disk::Disk};

#[derive(Default)]
pub struct Left {
    command_tx: Option<UnboundedSender<Action>>,
    config: Config,
    title_text: String,
    item_list: StatefulList<Disk>,
    mode: Mode,
    selections: Vec<Option<usize>>,
}

impl Left {
    pub fn new() -> Self {
        Self {
            selections: vec![None, None],
            title_text: String::from("Home"),
            ..Default::default()
        }
    }
}

impl Component for Left {
    fn handle_key_event(&mut self, key: KeyEvent) -> Result<Option<Action>> {
        // TODO
        let _ = key; // to appease clippy
        Ok(None)
    }

    fn register_action_handler(&mut self, tx: UnboundedSender<Action>) -> Result<()> {
        self.command_tx = Some(tx);
        Ok(())
    }

    fn register_config_handler(&mut self, config: Config) -> Result<()> {
        self.config = config;
        Ok(())
    }

    fn update(&mut self, action: Action) -> Result<Option<Action>> {
        match action {
            Action::Tick => {
                // add any logic here that should run on every tick
            }
            Action::Render => {
                // add any logic here that should run on every render
            }
            Action::KeyUp => self.item_list.previous(),
            Action::KeyDown => self.item_list.next(),
            Action::Process => match self.mode {
                Mode::Confirm => {
                    if let Some(command_tx) = self.command_tx.clone() {
                        command_tx.send(Action::NextScreen)?;
                    }
                }
                Mode::SelectDisks | Mode::SelectParts => {
                    if let Some(index) = self.item_list.state.selected() {
                        if let Some(command_tx) = self.command_tx.clone() {
                            let mut selection_one: Option<usize> = None;
                            let mut selection_two: Option<usize> = None;

                            // Get selection(s)
                            if self.selections[0].is_none() {
                                // First selection
                                selection_one = Some(index);
                                selection_two = None;
                            } else {
                                // Second selection
                                if let Some(source_index) = self.selections[0] {
                                    if index != source_index {
                                        selection_one = self.selections[0];
                                        selection_two = Some(index);
                                    }
                                }
                            }

                            // Send selection(s)
                            // NOTE: This is needed to keep the app and all components in sync
                            match self.mode {
                                Mode::SelectDisks => {
                                    command_tx
                                        .send(Action::Select(selection_one, selection_two))?;
                                }
                                Mode::SelectParts => {
                                    command_tx
                                        .send(Action::Select(selection_one, selection_two))?;
                                }
                                _ => {}
                            };

                            // Advance screen if both selections made
                            if selection_two.is_some() {
                                command_tx.send(Action::NextScreen)?;
                            }
                        }
                    }
                }
                _ => {}
            },
            Action::Select(Some(index), None) => self.selections[0] = Some(index),
            Action::SetMode(new_mode) => {
                let prev_mode = self.mode;
                self.mode = new_mode;
                match new_mode {
                    Mode::ScanDisks => {
                        self.title_text = String::from("");
                        self.item_list.clear_items();
                    }
                    Mode::SelectDisks => {
                        self.selections[0] = None;
                        self.selections[1] = None;
                        self.title_text = String::from("Select Source and Destination Disks");
                        if let Some(command_tx) = self.command_tx.clone() {
                            command_tx.send(Action::DismissPopup)?;
                        }
                    }
                    Mode::SelectParts => {
                        self.selections[0] = None;
                        self.selections[1] = None;
                        self.title_text = String::from("Select Boot and OS Partitions")
                    }
                    Mode::Confirm => match prev_mode {
                        Mode::SelectDisks => self.title_text = String::from("Confirm Selections"),
                        Mode::SelectParts => {
                            self.title_text = String::from("Confirm Selections (Again)")
                        }
                        _ => {}
                    },

                    Mode::Done => self.title_text = String::from("Done"),
                }
            }
            Action::UpdateDiskList(disks) => self.item_list.set_items(disks),
            _ => {}
        }
        Ok(None)
    }

    fn draw(&mut self, frame: &mut Frame, area: Rect) -> Result<()> {
        let [title_area, body_area] = Layout::default()
            .direction(Direction::Vertical)
            .constraints([Constraint::Length(1), Constraint::Min(1)])
            .areas(area);

        // Title
        let title =
            Paragraph::new(Line::from(Span::styled(&self.title_text, Style::default())).centered())
                .block(Block::default().borders(Borders::NONE));
        frame.render_widget(title, title_area);

        // Body (scan disks)
        if self.item_list.items.is_empty() {
            let paragraph = Paragraph::new(String::new()).block(
                Block::default()
                    .borders(Borders::ALL)
                    .padding(Padding::new(1, 1, 1, 1)),
            );
            frame.render_widget(paragraph, body_area);

            // Bail early
            return Ok(());
        }

        // Body (confirm)
        if self.mode == Mode::Confirm {
            let paragraph = Paragraph::new(String::from("Are the listed selections correct?"))
                .block(
                    Block::default()
                        .borders(Borders::ALL)
                        .padding(Padding::new(1, 1, 1, 1)),
                );
            frame.render_widget(paragraph, body_area);

            // Bail early
            return Ok(());
        }

        // Body (list)
        let mut list_items = Vec::<ListItem>::new();
        if !self.item_list.items.is_empty() {
            for (index, item) in self.item_list.items.iter().enumerate() {
                let mut item_style = Style::default();
                let mut item_text_tail = "";
                if let Some(selection_one) = self.selections[0] {
                    if selection_one == index {
                        item_style = Style::new().yellow();
                        item_text_tail = "      ~already selected~";
                    }
                }
                list_items.push(
                    ListItem::new(format!("    {item}\n{item_text_tail}\n\n")).style(item_style),
                );
            }
        }
        let list = List::new(list_items)
            .block(
                Block::default()
                    .borders(Borders::ALL)
                    .padding(Padding::new(1, 1, 1, 1)),
            )
            .highlight_spacing(HighlightSpacing::Always)
            .highlight_style(Style::new().green().bold())
            .highlight_symbol(" --> ")
            .repeat_highlight_symbol(false);
        frame.render_stateful_widget(list, body_area, &mut self.item_list.state);

        // Done
        Ok(())
    }
}