use crate::tui::component::{Action, Component};
use crate::tui::editor::Editor;
use crate::tui::explorer::Explorer;
use anyhow::{Result, anyhow};
use ratatui::buffer::Buffer;
use ratatui::crossterm::event;
use ratatui::crossterm::event::{Event, KeyCode, KeyEvent, KeyEventKind, KeyModifiers};
use ratatui::layout::{Constraint, Direction, Layout, Rect};
use ratatui::prelude::{Color, Style, Widget};
use ratatui::widgets::{Block, Borders, Padding, Paragraph, Tabs, Wrap};
use ratatui::{DefaultTerminal, symbols};
use std::path::PathBuf;
use std::time::Duration;

pub enum AppComponents<'a> {
    AppEditor(Editor),
    AppExplorer(Explorer<'a>),
    AppComponent(Box<dyn Component>),
}

pub struct App<'a> {
    components: Vec<AppComponents<'a>>,
}

impl<'a> App<'a> {
    pub(crate) fn new(root_path: PathBuf) -> Self {
        let mut app = Self {
            components: vec![
                AppComponents::AppExplorer(Explorer::new(&root_path)),
                AppComponents::AppEditor(Editor::new()),
            ],
        };
        app.get_editor_mut()
            .unwrap()
            .set_contents(&root_path.join("src/tui/app.rs"))
            .expect("Failed to set editor contents.");
        app
    }

    fn get_explorer(&self) -> Result<&Explorer<'a>> {
        for component in &self.components {
            if let AppComponents::AppExplorer(explorer) = component {
                return Ok(explorer);
            }
        }
        Err(anyhow::anyhow!("Failed to find project explorer widget."))
    }

    fn get_explorer_mut(&mut self) -> Result<&mut Explorer<'a>> {
        for component in &mut self.components {
            if let AppComponents::AppExplorer(explorer) = component {
                return Ok(explorer);
            }
        }
        Err(anyhow::anyhow!("Failed to find project explorer widget."))
    }

    fn get_editor(&self) -> Option<&Editor> {
        for component in &self.components {
            if let AppComponents::AppEditor(editor) = component {
                return Some(editor);
            }
        }

        // There is no editor currently opened.
        None
    }

    fn get_editor_mut(&mut self) -> Option<&mut Editor> {
        for component in &mut self.components {
            if let AppComponents::AppEditor(editor) = component {
                return Some(editor);
            }
        }

        // There is no editor currently opened.
        None
    }

    fn get_event(&mut self) -> Option<Event> {
        if !event::poll(Duration::from_millis(250)).expect("event poll failed") {
            return None;
        }

        event::read().ok()
    }

    pub fn run(mut self, mut terminal: DefaultTerminal) -> Result<()> {
        loop {
            // TODO: Handle events based on which component is active.
            terminal.draw(|f| {
                f.render_widget(&mut self, f.area());
            })?;

            if let Some(event) = self.get_event() {
                match self.handle_event(event) {
                    Action::Quit => break,
                    Action::Handled => {}
                    _ => {
                        // panic!("Unhandled event: {:?}", event);
                    }
                }
            }
        }
        Ok(())
    }

    fn draw_status(&self, area: Rect, buf: &mut Buffer) {
        // TODO: Status bar should have drop down menus
        Tabs::new(["File", "Edit", "View", "Help"])
            .style(Style::default())
            .block(Block::default().borders(Borders::ALL))
            .render(area, buf);
    }

    fn draw_tabs(&self, area: Rect, buf: &mut Buffer) {
        // Determine the tab title from the current file (or use a fallback).
        let mut title: Option<&str> = None;
        if let Some(editor) = self.get_editor() {
            title = editor
                .file_path
                .as_ref()
                .and_then(|p| p.file_name())
                .and_then(|s| s.to_str())
        }

        Tabs::new(vec![title.unwrap_or("Unknown")])
            .divider(symbols::DOT)
            .block(
                Block::default()
                    .borders(Borders::NONE)
                    .padding(Padding::new(0, 0, 0, 0)),
            )
            .highlight_style(Style::default().fg(Color::LightRed))
            .render(area, buf);
    }

    fn draw_terminal(&self, area: Rect, buf: &mut Buffer) {
        // TODO: Title should be detected shell name
        // TODO: Contents should be shell output
        Paragraph::new("shaun@pc:~/Code/clide$ ")
            .style(Style::default())
            .block(
                Block::default()
                    .title("Bash")
                    .title_style(Style::default().fg(Color::DarkGray))
                    .borders(Borders::ALL),
            )
            .wrap(Wrap { trim: false })
            .render(area, buf);
    }

    /// Refresh the contents of the editor to match the selected TreeItem in the file Explorer.
    /// If the selected item is not a file, this does nothing.
    fn refresh_editor_contents(&mut self) -> Result<()> {
        // Use the currently selected TreeItem or get an absolute path to this source file.
        let selected_pathbuf = match self.get_explorer()?.selected() {
            Ok(path) => PathBuf::from(path),
            Err(_) => PathBuf::from(std::path::absolute(file!())?.to_string_lossy().to_string()),
        };
        let editor = self
            .get_editor_mut()
            .expect("Failed to get active editor while refreshing contents.");
        if let Some(current_file_path) = editor.file_path.clone() {
            if selected_pathbuf == current_file_path || !selected_pathbuf.is_file() {
                return Ok(());
            }
            return editor.set_contents(&selected_pathbuf);
        }
        Err(anyhow!("Failed to refresh editor contents"))
    }
}

// TODO: Separate complex components into their own widgets.
impl<'a> Widget for &mut App<'a> {
    fn render(self, area: Rect, buf: &mut Buffer)
    where
        Self: Sized,
    {
        let vertical = Layout::default()
            .direction(Direction::Vertical)
            .constraints([
                Constraint::Length(3),      // status bar
                Constraint::Percentage(70), // horizontal layout
                Constraint::Percentage(30), // terminal
            ])
            .split(area);

        let horizontal = Layout::default()
            .direction(Direction::Horizontal)
            .constraints([
                Constraint::Max(30), // File explorer with a max width of 30 characters.
                Constraint::Fill(1), // Editor fills the remaining space.
            ])
            .split(vertical[1]);

        let editor_layout = Layout::default()
            .direction(Direction::Vertical)
            .constraints([
                Constraint::Length(1), // Editor tabs.
                Constraint::Fill(1),   // Editor contents.
            ])
            .split(horizontal[1]);

        self.draw_status(vertical[0], buf);
        self.draw_terminal(vertical[2], buf);
        if let Ok(explorer) = self.get_explorer_mut() {
            explorer.render(horizontal[0], buf);
        }
        self.draw_tabs(editor_layout[0], buf);
        self.refresh_editor_contents()
            .expect("Failed to refresh editor contents.");
        self.get_editor_mut().unwrap().render(editor_layout[1], buf);
    }
}

impl<'a> Component for App<'a> {
    fn id(&self) -> &str {
        "app"
    }

    /// TODO: Get active widget with some Component trait function helper?
    /// trait Component { fn get_state() -> ComponentState; }
    /// if component.get_state() = ComponentState::Active { component.handle_event(); }
    ///
    /// App could then provide helpers for altering Component state based on TUI grouping..
    ///    (such as editor tabs, file explorer, status bars, etc..)
    ///
    /// Handles events for the App and delegates to attached Components.
    fn handle_event(&mut self, event: Event) -> Action {
        // Handle events in the primary application.
        if let Some(key_event) = event.as_key_event() {
            match self.handle_key_events(key_event) {
                Action::Quit => return Action::Quit,
                Action::Handled => return Action::Handled,
                _ => {}
            }
        }

        // Handle events for all components.
        for component in &mut self.components {
            let action = match component {
                AppComponents::AppEditor(editor) => editor.handle_event(event.clone()),
                AppComponents::AppExplorer(explorer) => explorer.handle_event(event.clone()),
                AppComponents::AppComponent(comp) => comp.handle_event(event.clone()),
            };
            // Actions returned here abort the input handling iteration.
            match action {
                Action::Quit | Action::Handled => return action,
                _ => {}
            }
        }
        Action::Noop
    }

    /// Handles key events for the App Component only.
    fn handle_key_events(&mut self, key: KeyEvent) -> Action {
        match key {
            KeyEvent {
                code: KeyCode::Char('c'),
                modifiers: KeyModifiers::CONTROL,
                kind: KeyEventKind::Press,
                state: _state,
            } => Action::Quit,
            _ => Action::Noop,
        }
    }
}