use std::io::{self, Write};

use crossterm::{
    cursor,
    event::{self, Event, KeyCode, KeyEvent, KeyModifiers},
    execute,
    style::{self, Stylize},
    terminal::{self, ClearType},
};

pub fn fuzzy_match(query: &str, name: &str) -> bool {
    let name_lower = name.to_lowercase();
    let mut chars = name_lower.chars();
    for qch in query.chars() {
        loop {
            match chars.next() {
                Some(ch) if ch == qch => break,
                Some(_) => continue,
                None => return false,
            }
        }
    }
    true
}

pub fn run_artist_picker(artists: &[(String, String)]) -> Option<(String, String)> {
    let mut stdout = io::stdout();
    terminal::enable_raw_mode().ok()?;
    execute!(stdout, terminal::EnterAlternateScreen, cursor::Hide).ok()?;

    let result = picker_loop(&mut stdout, artists);

    execute!(stdout, cursor::Show, terminal::LeaveAlternateScreen).ok();
    terminal::disable_raw_mode().ok();

    result
}

fn picker_loop(stdout: &mut io::Stdout, artists: &[(String, String)]) -> Option<(String, String)> {
    let mut query = String::new();
    let mut selected: usize = 0;
    let mut scroll: usize = 0;

    loop {
        let (w, h) = terminal::size().ok()?;
        let w = w as usize;
        let h = h as usize;
        if h < 2 {
            continue;
        }

        let q = query.to_lowercase();
        let filtered: Vec<&(String, String)> = if q.is_empty() {
            artists.iter().collect()
        } else {
            artists.iter().filter(|(_, name)| fuzzy_match(&q, name)).collect()
        };

        if filtered.is_empty() {
            selected = 0;
        } else {
            selected = selected.min(filtered.len() - 1);
        }

        // Scroll bounds
        let list_h = h - 1;
        if selected < scroll {
            scroll = selected;
        }
        if selected >= scroll + list_h {
            scroll = selected - list_h + 1;
        }

        // Draw
        execute!(stdout, terminal::Clear(ClearType::All)).ok();

        // Prompt line
        let prompt = format!(" > {query}");
        let count_str = format!("  {}/{}", filtered.len(), artists.len());
        execute!(
            stdout,
            cursor::MoveTo(0, 0),
            style::PrintStyledContent(prompt.as_str().cyan().bold()),
            style::PrintStyledContent(count_str.as_str().dark_grey()),
        )
        .ok();

        // Artist list
        for i in 0..list_h {
            let idx = scroll + i;
            if idx >= filtered.len() {
                break;
            }
            let (_, name) = filtered[idx];
            let display: String = if name.len() >= w {
                name[..w].to_string()
            } else {
                format!(" {name}")
            };
            execute!(stdout, cursor::MoveTo(0, (i + 1) as u16)).ok();
            if idx == selected {
                execute!(
                    stdout,
                    style::PrintStyledContent(display.as_str().black().on_cyan()),
                )
                .ok();
            } else {
                execute!(stdout, style::Print(&display)).ok();
            }
        }

        stdout.flush().ok();

        // Input
        let Event::Key(KeyEvent { code, modifiers, .. }) = event::read().ok()? else {
            continue;
        };

        match code {
            KeyCode::Esc => return None,
            KeyCode::Enter => {
                if !filtered.is_empty() {
                    let (mbid, name) = filtered[selected];
                    return Some((mbid.clone(), name.clone()));
                }
            }
            KeyCode::Up => {
                selected = selected.saturating_sub(1);
            }
            KeyCode::Down => {
                if !filtered.is_empty() {
                    selected = selected.min(filtered.len().saturating_sub(1));
                    if selected + 1 < filtered.len() {
                        selected += 1;
                    }
                }
            }
            KeyCode::Char('p') if modifiers.contains(KeyModifiers::CONTROL) => {
                selected = selected.saturating_sub(1);
            }
            KeyCode::Char('n') if modifiers.contains(KeyModifiers::CONTROL) => {
                if !filtered.is_empty() && selected + 1 < filtered.len() {
                    selected += 1;
                }
            }
            KeyCode::Backspace => {
                query.pop();
                selected = 0;
                scroll = 0;
            }
            KeyCode::Char(ch) => {
                query.push(ch);
                selected = 0;
                scroll = 0;
            }
            _ => {}
        }
    }
}