use crossterm::{
    event::{
        DisableMouseCapture, EnableMouseCapture, KeyEventKind, KeyEventState, MouseButton,
        MouseEventKind,
    },
    terminal::{EnterAlternateScreen, LeaveAlternateScreen},
};
use ratatui_themes::{Theme, ThemeName};
use std::{
    fs::{self, DirEntry},
    io::{self, Stdout},
    ops::ControlFlow,
    path::{Path, PathBuf},
    process::exit,
    sync::Arc,
    time::Duration,
};
use tui_widget_list::{ListBuilder, ListView};

use crate::tui::{
    filter::{Filter, FilterKind, Matcher},
    log_viewer::{
        LogViewer,
        input::{FieldMatcher, InputState, InputTarget},
    },
    reader::LogfileReader,
    widgets::{hyperlink::Hyperlink, items::Items, last_error::LastError, styled::IntoStyled},
};
use ratatui::{
    DefaultTerminal, Terminal,
    buffer::Buffer,
    crossterm::event::{self, Event, KeyCode, KeyEvent, KeyModifiers},
    layout::{Constraint, HorizontalAlignment, Layout, Rect},
    prelude::CrosstermBackend,
    style::Style,
    text::Line,
    widgets::{
        Block, Clear, List, ListItem, ListState, Padding, Paragraph, StatefulWidget, Widget, Wrap,
    },
};

pub mod filter;
pub mod log_viewer;
pub mod model;
pub mod processing;
pub mod reader;
pub mod widgets;

const HELP_TEXT: &str = "Generic:
    ?                   show help
    <esc>               cancel focus or close tab
    u                   undo
    r                   redo
    pgdwn&pgup          move page
    down&up             move single
    j&k                 move single
    Home/G              move to start

    <- / backspace / h  exit nested view
    -> / enter / l      enter nested view

───────────────────────────────────────────────────────
targeting logs:

    f                   fields
    t                   the selected log
    s                   surrounding element

either a field after `f` or the text of the current log:
    p                   ... with a prefix
    /                   ... matching a regex
    e                   ... equal to selected
    c                   ... containing

───────────────────────────────────────────────────────
perform action on selected target:

    alt-d                   delete
    alt-i                   inline
";

fn setup_terminal() -> io::Result<Terminal<CrosstermBackend<Stdout>>> {
    let mut stdout = io::stdout();
    crossterm::terminal::enable_raw_mode()?;
    {
        use ::std::io::Write;
        crossterm::queue!(stdout, EnterAlternateScreen, EnableMouseCapture)
            .and_then(|()| ::std::io::Write::flush(stdout.by_ref()))
    }?;
    Terminal::new(CrosstermBackend::new(stdout))
}

fn teardown_terminal(_terminal: &mut Terminal<CrosstermBackend<Stdout>>) -> io::Result<()> {
    let mut stdout = io::stdout();
    crossterm::terminal::disable_raw_mode()?;
    crossterm::execute!(stdout, LeaveAlternateScreen, DisableMouseCapture,)?;
    Ok(())
}

pub fn run(logs_dir: PathBuf, compiler_root: Option<PathBuf>, theme: ThemeName) {
    let mut terminal = setup_terminal().unwrap();
    let theme = Theme::new(theme);
    let app_result = App::new(logs_dir, compiler_root, theme).run(&mut terminal);
    teardown_terminal(&mut terminal).unwrap();

    if let Err(e) = app_result {
        eprintln!("error in tui: {e:?}");
        exit(1);
    }
}

enum Tab {
    FileChooser {
        files: Vec<DirEntry>,
        state: ListState,
        last_height: usize,
        last_offset: usize,
    },
    LogViewer(LogViewer),
    Empty,
    Help,
}

impl Tab {
    fn name(&self, path: Option<&Path>) -> String {
        match (self, path) {
            (Tab::Empty, _) => "dummy".to_string(),
            (Tab::FileChooser { .. }, _) => "choose a file".to_string(),
            (Tab::LogViewer(_), Some(path)) => format!("logs of {}", path.display()),
            (Tab::LogViewer(_), None) => "logs".to_string(),
            (Tab::Help, _) => "help".to_string(),
        }
    }
}

struct App {
    tabs: Vec<Tab>,
    logs_dir: PathBuf,
    compiler_root: Option<PathBuf>,
    current_file: Option<LogfileReader>,
    theme: Theme,

    last_error: LastError,
}

impl App {
    fn new(logs_dir: PathBuf, compiler_root: Option<PathBuf>, theme: Theme) -> Self {
        let mut res = Self {
            tabs: Vec::new(),
            current_file: None,
            logs_dir,
            compiler_root,
            theme,
            last_error: LastError::new(),
        };
        res.replace_tab(res.choose_file());
        res
    }

    fn current_file_path(&self) -> Option<PathBuf> {
        self.current_file.as_ref().map(|i| i.path())
    }

    fn replace_tab(&mut self, tab: Tab) {
        if let Some(last) = self.tabs.last_mut() {
            *last = tab;
        } else {
            self.tabs = vec![tab];
        }
    }

    fn push_tab(&mut self, tab: Tab) {
        self.tabs.push(tab);
    }

    fn pop_tab(&mut self) {
        let _ = self.tabs.pop();
    }

    fn choose_file(&self) -> Tab {
        fn init(logs_dir: &Path) -> io::Result<Vec<DirEntry>> {
            let mut files = Vec::new();

            for file in fs::read_dir(logs_dir)? {
                let file = file?;
                if file.path().extension().is_some_and(|ext| ext == "log") {
                    files.push(file);
                }
            }

            Ok(files)
        }

        match init(&self.logs_dir) {
            Ok(files) => Tab::FileChooser {
                files,
                state: ListState::default(),
                last_height: 0,
                last_offset: 0,
            },
            Err(_) => Tab::Empty,
        }
    }

    fn current_tab(&mut self) -> &mut Tab {
        if self.tabs.is_empty() {
            self.tabs.push(Tab::Empty);
        }

        self.tabs.last_mut().unwrap()
    }

    fn start_log_viewer(&mut self, path: PathBuf) {
        let filters_path = path.with_added_extension("filters.json");
        match LogfileReader::new(&path) {
            Ok(i) => {
                self.current_file = Some(i.clone());

                if let Some(first) = i.first() {
                    self.replace_tab(Tab::LogViewer(LogViewer::new(
                        first,
                        filters_path,
                        self.last_error.clone(),
                    )));
                } else {
                    panic!("no log entries");
                }
            }
            Err(_) => {
                panic!()
            }
        }
    }

    fn handle_current_tab_keycode(&mut self, key: KeyEvent) {
        match self.tabs.last_mut().unwrap() {
            Tab::Help => {}
            Tab::Empty => {}
            Tab::FileChooser {
                files,
                state,
                last_height,
                last_offset: _,
            } => match key.code {
                KeyCode::Char('j') | KeyCode::Down => state.select_next(),
                KeyCode::Char('k') | KeyCode::Up => state.select_previous(),
                KeyCode::PageUp => state.scroll_up_by(*last_height as u16),
                KeyCode::PageDown => state.scroll_down_by(*last_height as u16),
                KeyCode::Char('G') | KeyCode::Home => state.select_first(),
                KeyCode::Char('g') | KeyCode::End => state.select_last(),
                KeyCode::Enter => {
                    if let Some(selected) = state.selected()
                        && let Some(selected) = files.get(selected)
                    {
                        let path = selected.path();
                        self.start_log_viewer(path);
                    }
                }
                _ => {}
            },
            Tab::LogViewer(lv) => match key.code {
                // delete
                KeyCode::Char('d') if key.modifiers.contains(KeyModifiers::ALT) => {
                    if let InputState::None = lv.input_state {
                        lv.input_state = InputState::Target(InputTarget::This);
                    }

                    if let InputState::Target(t) = lv.input_state.clone()
                        && let Some(m) = Matcher::from_input(t, lv)
                    {
                        lv.add_filter(Arc::new(Filter {
                            matcher: m,
                            kind: FilterKind::Remove,
                        }));
                        lv.input_state.reset();
                    }
                }
                // inline
                KeyCode::Char('i') if key.modifiers.contains(KeyModifiers::ALT) => {
                    if let InputState::None = lv.input_state {
                        lv.input_state = InputState::Target(InputTarget::This);
                    }

                    if let InputState::Target(t) = lv.input_state.clone()
                        && let Some(m) = Matcher::from_input(t, lv)
                    {
                        lv.add_filter(Arc::new(Filter {
                            matcher: m,
                            kind: FilterKind::Inline,
                        }));
                        lv.input_state.reset();
                    }
                }
                KeyCode::Char(c) if lv.input_state.captures_input() => {
                    lv.input_state.capture_string().unwrap().push(c);
                }
                KeyCode::Backspace if lv.input_state.captures_input() => {
                    lv.input_state.capture_string().unwrap().pop();
                }
                KeyCode::Esc if lv.input_state.captures_input() => {
                    if let InputState::Target(InputTarget::Fields(s @ Some(_))) =
                        &mut lv.input_state
                    {
                        *s = None
                    } else {
                        lv.input_state.reset();
                    }
                }
                _ if lv.input_state.captures_input() => {}
                KeyCode::Char('j') | KeyCode::Down => lv.next(),
                KeyCode::Char('k') | KeyCode::Up => lv.prev(),
                KeyCode::PageUp => lv.page_up(),
                KeyCode::PageDown => lv.page_down(),
                KeyCode::Char('G') | KeyCode::Home => lv.home(),
                KeyCode::Char('g') | KeyCode::End => todo!(),
                KeyCode::Backspace | KeyCode::Left => lv.back(),
                KeyCode::Right => lv.enter(),
                KeyCode::Enter => lv.enter(),

                KeyCode::Char('u') => lv.undo(),
                KeyCode::Char('r') => lv.redo(),

                KeyCode::Char('f') => {
                    lv.input_state.target(InputTarget::Fields(None));
                    lv.footer_list.select(Some(0));
                }
                KeyCode::Esc => lv.input_state.reset(),
                KeyCode::Char('s') if !lv.view.cursor.toplevel() => {
                    lv.input_state.target(InputTarget::Surround);
                }
                KeyCode::Char('t') => {
                    lv.input_state.target(InputTarget::This);
                }
                KeyCode::Char('/') => {
                    let v = FieldMatcher::Regex(String::new());
                    if let InputState::Target(InputTarget::Fields(f @ None)) = &mut lv.input_state {
                        *f = Some(v);
                    } else {
                        lv.input_state.target(InputTarget::Text(v));
                    }
                }
                KeyCode::Char('p') => {
                    let v = FieldMatcher::Prefix(String::new());
                    if let InputState::Target(InputTarget::Fields(f @ None)) = &mut lv.input_state {
                        *f = Some(v);
                    } else {
                        lv.input_state.target(InputTarget::Text(v));
                    }
                }
                KeyCode::Char('c') => {
                    let v = FieldMatcher::Contains(String::new());
                    if let InputState::Target(InputTarget::Fields(f @ None)) = &mut lv.input_state {
                        *f = Some(v);
                    } else {
                        lv.input_state.target(InputTarget::Text(v));
                    }
                }
                KeyCode::Char('e') => {
                    let v = FieldMatcher::EqualTo;
                    if let InputState::Target(InputTarget::Fields(f @ None)) = &mut lv.input_state {
                        *f = Some(v);
                    } else {
                        lv.input_state.target(InputTarget::Text(v));
                    }
                }
                _ => {}
            },
        }
    }

    fn handle_generic_keycode(
        &mut self,
        key: KeyEvent,
        terminal: &mut DefaultTerminal,
    ) -> ControlFlow<()> {
        let num_tabs = self.tabs.len();
        match key.code {
            KeyCode::Char('q') => return ControlFlow::Break(()),
            KeyCode::Char('c') if key.modifiers.contains(KeyModifiers::CONTROL) => {
                return ControlFlow::Break(());
            }
            KeyCode::Char('z') if key.modifiers.contains(KeyModifiers::CONTROL) => {
                ratatui::restore();
                let self_pid = nix::unistd::getpid();
                let _ = nix::sys::signal::kill(self_pid, nix::sys::signal::SIGTSTP);
                *terminal = setup_terminal().unwrap();
            }
            KeyCode::Char('?') => {
                if matches!(self.current_tab(), Tab::Help) {
                    self.pop_tab();
                } else {
                    self.push_tab(Tab::Help);
                }
            }
            KeyCode::Esc if num_tabs > 1 => {
                self.pop_tab();
            }
            _ => {
                self.handle_current_tab_keycode(key);
            }
        }

        ControlFlow::Continue(())
    }

    fn run(mut self, terminal: &mut DefaultTerminal) -> io::Result<()> {
        loop {
            self.last_error.check_expired();

            terminal.draw(|frame| frame.render_widget(&mut self, frame.area()))?;

            // update every 250ms or more if there's an event
            if !event::poll(Duration::from_millis(250))? {
                continue;
            }

            match event::read()? {
                Event::Key(key) => {
                    // to initialize, but we then do get manually for borrow reasons
                    self.current_tab();

                    // always active
                    if self.handle_generic_keycode(key, terminal).is_break() {
                        break Ok(());
                    }
                }
                Event::FocusGained => {}
                Event::FocusLost => {}
                Event::Mouse(mouse) if mouse.kind == MouseEventKind::ScrollDown => {
                    if self
                        .handle_generic_keycode(
                            KeyEvent {
                                code: KeyCode::Down,
                                modifiers: KeyModifiers::empty(),
                                kind: KeyEventKind::Press,
                                state: KeyEventState::empty(),
                            },
                            terminal,
                        )
                        .is_break()
                    {
                        break Ok(());
                    }
                }
                Event::Mouse(mouse) if mouse.kind == MouseEventKind::ScrollUp => {
                    if self
                        .handle_generic_keycode(
                            KeyEvent {
                                code: KeyCode::Up,
                                modifiers: KeyModifiers::empty(),
                                kind: KeyEventKind::Press,
                                state: KeyEventState::empty(),
                            },
                            terminal,
                        )
                        .is_break()
                    {
                        break Ok(());
                    }
                }
                Event::Mouse(mouse_event) => {
                    if let MouseEventKind::Up(MouseButton::Left) = mouse_event.kind {
                        if let Tab::LogViewer(lv) = self.current_tab() {
                            lv.click(mouse_event.row);
                        } else if let Tab::FileChooser {
                            files,
                            state,
                            last_height: _,
                            last_offset,
                        } = self.current_tab()
                        {
                            if mouse_event.row as usize > *last_offset {
                                let row = mouse_event.row as usize - *last_offset;
                                if row < files.len() {
                                    if state.selected() == Some(row)
                                        && let Some(selected) = files.get(row)
                                    {
                                        let path = selected.path();
                                        self.start_log_viewer(path);
                                    } else {
                                        state.select(Some(row));
                                    }
                                }
                            }
                        }
                    }
                }
                Event::Paste(_) => {}
                Event::Resize(_, _) => {}
            }
        }
    }

    fn styles(&self) -> Styles {
        let palette = self.theme.palette();
        let default = Style::new().fg(palette.fg).bg(palette.bg);
        let highlighted = Style::new().fg(palette.accent).bg(palette.selection);
        let border = Style::new().fg(palette.fg).bg(palette.bg);
        let border_highlighted = Style::new().fg(palette.secondary).bg(palette.bg);
        let error = Style::new().fg(palette.error).bg(palette.bg);

        Styles {
            default,
            highlighted,
            border,
            border_highlighted,
            error,
        }
    }

    pub fn block_around(&self, area: Rect, buf: &mut Buffer, selected: bool) -> Rect {
        let styles = self.styles();
        let block = Block::bordered()
            .style(styles.default)
            .border_style(if selected {
                styles.border_highlighted
            } else {
                styles.border
            });
        let inner = block.inner(area);
        block.render(area, buf);
        inner
    }
}

pub struct Styles {
    default: Style,
    highlighted: Style,
    border: Style,
    border_highlighted: Style,
    error: Style,
}

impl Widget for &mut App {
    fn render(self, area: Rect, buf: &mut Buffer)
    where
        Self: Sized,
    {
        let styles = self.styles();
        let [header_area, main_area, footer_area] = Layout::vertical([
            Constraint::Length(2),
            Constraint::Fill(1),
            Constraint::Ratio(1, 4),
        ])
        .areas(area);

        let [_, popup_area, _] = Layout::vertical([
            Constraint::Fill(1),
            Constraint::Min(40),
            Constraint::Fill(1),
        ])
        .areas(area);
        let [_, popup_area, _] = Layout::horizontal([
            Constraint::Fill(1),
            Constraint::Min(40),
            Constraint::Fill(1),
        ])
        .areas(popup_area);

        let (footer_focused, header_focused) = match self.current_tab() {
            Tab::Help => (false, false),
            Tab::FileChooser { .. } => (false, true),
            Tab::LogViewer(lv) => {
                let target_fields =
                    matches!(lv.input_state, InputState::Target(InputTarget::Fields(..)));
                (target_fields, !target_fields)
            }
            Tab::Empty => (false, false),
        };

        let main_area = self.block_around(main_area, buf, header_focused);
        let footer_area = self.block_around(footer_area, buf, footer_focused);

        let [left, middle, right] = Layout::horizontal([
            Constraint::Ratio(1, 3),
            Constraint::Ratio(1, 3),
            Constraint::Fill(1),
        ])
        .areas(header_area);

        let current_file_path = self.current_file_path();
        let breadcrumbs = self.tabs[..self.tabs.len() - 1]
            .iter()
            .map(|i| i.name(current_file_path.as_deref()))
            .collect::<Vec<_>>()
            .join("►");
        Paragraph::new(breadcrumbs)
            .wrap(Wrap { trim: false })
            .style(styles.default)
            .render(left, buf);

        Paragraph::new(self.current_tab().name(current_file_path.as_deref()))
            .alignment(HorizontalAlignment::Center)
            .wrap(Wrap { trim: false })
            .style(styles.default)
            .render(middle, buf);

        let [right, error] =
            Layout::vertical([Constraint::Length(1), Constraint::Length(1)]).areas(right);
        Paragraph::new("").style(styles.default).render(right, buf);

        for tab in &mut self.tabs {
            match tab {
                Tab::FileChooser {
                    files,
                    state,
                    last_height,
                    last_offset,
                } => {
                    let list = List::new(files.iter().map(|file| {
                        ListItem::new(file.file_name().to_string_lossy().into_owned())
                    }))
                    .style(styles.default)
                    .highlight_style(styles.highlighted);

                    *last_height = main_area.height as usize;
                    *last_offset = main_area.y as usize;

                    StatefulWidget::render(list, main_area, buf, state);
                }
                Tab::LogViewer(lv) => {
                    lv.last_offset = main_area.y as usize;
                    lv.update_num_items(main_area.height as usize);

                    let (items, selected_offset) = lv
                        .items(main_area.height as usize)
                        .unwrap_or_else(|| (Vec::new(), 0));

                    lv.input_state.styled_ref(&styles).render(right, buf);

                    Clear.render(footer_area, buf);
                    let [first_line, footer_area] =
                        Layout::vertical([Constraint::Length(1), Constraint::Fill(1)])
                            .areas(footer_area);
                    if let Some((e, _)) = lv.selected() {
                        let rustc_root = self.compiler_root.as_ref();
                        let (file, line) = e.file_line_string();

                        if let Some(rustc_root) = rustc_root
                            && let Ok(canonical_rustc_root) = rustc_root.canonicalize()
                        {
                            let full_file_path = canonical_rustc_root.join(&file);
                            Hyperlink::new(
                                Line::from(format!("In file: {}:{line}", file.display()))
                                    .style(styles.default),
                                format!("file://{}", full_file_path.display()),
                            )
                            .render(first_line, buf);
                        } else {
                            Line::from(format!("In file: {}:{line}", file.display()))
                                .style(styles.default)
                                .render(first_line, buf);
                        }
                    }

                    Items::new(
                        items,
                        &lv.filters,
                        selected_offset,
                        &lv.input_state,
                        lv.footer_list.selected.and_then(|idx| {
                            lv.footer_fields()
                                .get(idx)
                                .map(|(a, b)| (a.clone(), b.clone()))
                        }),
                        self.last_error.clone(),
                    )
                    .styled_ref(&styles)
                    .render(main_area, buf);

                    let items = lv.footer_fields();
                    lv.last_fields_offset = footer_area.y as usize;
                    lv.last_fields_height = items.len();

                    let width = 20;
                    let builder = ListBuilder::new(|cx| {
                        let Some((k, v)) = &items.get(cx.index) else {
                            return (Paragraph::new(""), 1);
                        };

                        let mut res =
                            Paragraph::new(format!("{k:width$} {v}")).wrap(Wrap { trim: false });

                        if cx.is_selected {
                            res = res.style(styles.highlighted);
                        }

                        let height = res.line_count(footer_area.width) as u16;
                        (res, height)
                    });

                    let list = ListView::new(builder, items.len()).style(styles.default);
                    StatefulWidget::render(list, footer_area, buf, &mut lv.footer_list);
                }
                Tab::Empty => {}
                Tab::Help => {
                    Clear.render(popup_area, buf);
                    let popup_area = {
                        let block = Block::bordered()
                            .title_top("help")
                            .style(styles.default)
                            .padding(Padding::symmetric(3, 1))
                            .border_style(styles.border_highlighted);
                        let inner = block.inner(popup_area);
                        block.render(popup_area, buf);
                        inner
                    };

                    Paragraph::new(HELP_TEXT).render(popup_area, buf);
                }
            }

            self.last_error.clone().styled(&styles).render(error, buf);
        }
    }
}