use ratatui::Frame;
use ratatui::layout::{Alignment, Constraint, Flex, Layout, Rect};
use ratatui::text::{Line, Span};
use ratatui::widgets::{Block, Clear, Paragraph, Wrap};

use super::theme;
use crate::app::state::{AppState, EditField, Loadable, Popup, addable_playlists};
use crate::library::models::{ArtistRef, TrackItem};

pub fn draw(frame: &mut Frame, state: &AppState) {
    match state.popup.as_ref() {
        Some(Popup::AddToPlaylist { track, cursor }) => {
            draw_picker(frame, state, &track.title, *cursor)
        }
        Some(Popup::NewPlaylist { input, busy, .. }) => draw_name_entry(frame, input, *busy),
        Some(Popup::Edit {
            title,
            fields,
            focus,
            error,
            ..
        }) => draw_edit(frame, title, fields, *focus, error.as_deref()),
        Some(Popup::ConfirmDelete { label, .. }) => draw_confirm_delete(frame, label),
        Some(Popup::TrackInfo {
            tracks,
            cursor,
            scroll,
        }) => draw_track_info(frame, tracks, *cursor, *scroll),
        Some(Popup::LogDetail(entry)) => draw_log_detail(frame, entry),
        Some(Popup::FedInput { field, input }) => draw_fed_input(frame, field.title(), input),
        Some(Popup::FedText { title, text }) => draw_fed_text(frame, title, text),
        None => {}
    }
}

/// One-line text entry on the Federation tab (network id / peer ticket).
fn draw_fed_input(frame: &mut Frame, title: &str, input: &crate::app::input::LineEdit) {
    let area = centered(frame.area(), 64, 5);
    let block = Block::bordered()
        .title(format!(" {title} "))
        .title_style(theme::header())
        .border_style(theme::accent());
    let inner = block.inner(area);
    frame.render_widget(Clear, area);
    frame.render_widget(block, area);
    let [entry_area, hint_area] =
        Layout::vertical([Constraint::Length(1), Constraint::Length(1)]).areas(inner);
    let spans = super::line_edit_spans(input, usize::from(entry_area.width.saturating_sub(1)));
    frame.render_widget(Paragraph::new(Line::from(spans)), entry_area);
    frame.render_widget(
        Paragraph::new(Line::styled("enter: apply · esc: cancel", theme::dim()))
            .alignment(Alignment::Center),
        hint_area,
    );
}

/// Read-only wrapped text (this peer's federation ticket).
fn draw_fed_text(frame: &mut Frame, title: &str, text: &str) {
    let width = frame.area().width.saturating_sub(8).clamp(24, 90);
    let text_width = usize::from(width.saturating_sub(2));
    let lines_needed = (text.chars().count() / text_width.max(1) + 3) as u16;
    let area = centered(frame.area(), width, lines_needed.clamp(5, frame.area().height));
    let block = Block::bordered()
        .title(format!(" {title} "))
        .title_style(theme::header())
        .border_style(theme::accent());
    let inner = block.inner(area);
    frame.render_widget(Clear, area);
    frame.render_widget(block, area);
    frame.render_widget(
        Paragraph::new(text.to_string()).wrap(Wrap { trim: false }),
        inner,
    );
}

/// Metadata edit form: one bordered input per field, the focused field gets
/// the accent border and a cursor block.
fn draw_edit(
    frame: &mut Frame,
    title: &str,
    fields: &[EditField],
    focus: usize,
    error: Option<&str>,
) {
    let height = (fields.len() as u16 * 3 + 4).min(frame.area().height.saturating_sub(2));
    let area = centered(frame.area(), 60, height);
    let block = Block::bordered()
        .title(format!(" {title} "))
        .title_style(theme::header())
        .border_style(theme::accent());
    let inner = block.inner(area);
    frame.render_widget(Clear, area);
    frame.render_widget(block, area);

    let mut constraints: Vec<Constraint> = fields.iter().map(|_| Constraint::Length(3)).collect();
    constraints.push(Constraint::Min(0));
    constraints.push(Constraint::Length(1));
    let areas = Layout::vertical(constraints).split(inner);

    for (index, field) in fields.iter().enumerate() {
        let focused = index == focus;
        let field_block = Block::bordered().title(field.label).border_style(if focused {
            theme::accent()
        } else {
            theme::dim()
        });
        let field_inner = field_block.inner(areas[index]);
        frame.render_widget(field_block, areas[index]);
        let width = usize::from(field_inner.width);
        if focused {
            let spans = super::line_edit_spans(&field.value, width);
            frame.render_widget(Paragraph::new(Line::from(spans)), field_inner);
        } else {
            let shown: String = field
                .value
                .chars()
                .skip(field.value.chars().count().saturating_sub(width))
                .collect();
            frame.render_widget(Paragraph::new(shown), field_inner);
        }
    }

    let footer = areas[areas.len() - 1];
    let hint = match error {
        Some(error) => Line::styled(error.to_string(), theme::accent()),
        None => Line::styled("tab/↑↓ field · enter save · esc cancel", theme::dim()),
    };
    frame.render_widget(Paragraph::new(hint).alignment(Alignment::Center), footer);
}

fn draw_confirm_delete(frame: &mut Frame, label: &str) {
    let width = 64.min(frame.area().width.saturating_sub(4)).max(30);
    let area = centered(frame.area(), width, 7);
    let block = Block::bordered()
        .title(" Delete? ")
        .title_style(theme::header())
        .border_style(theme::accent());
    let inner = block.inner(area);
    frame.render_widget(Clear, area);
    frame.render_widget(block, area);

    let [body, footer] = Layout::vertical([Constraint::Min(1), Constraint::Length(1)]).areas(inner);
    frame.render_widget(
        Paragraph::new(format!("Delete {label}?"))
            .wrap(Wrap { trim: false })
            .alignment(Alignment::Center),
        body,
    );
    frame.render_widget(
        Paragraph::new(Line::styled("enter/y delete · esc/n cancel", theme::dim()))
            .alignment(Alignment::Center),
        footer,
    );
}

fn draw_log_detail(frame: &mut Frame, entry: &crate::config::logging::LogEntry) {
    let width = 90.min(frame.area().width.saturating_sub(4)).max(40);
    let height = 18.min(frame.area().height.saturating_sub(2)).max(7);
    let area = centered(frame.area(), width, height);

    let block = Block::bordered()
        .title(format!(" Log entry — {} {} ", entry.time, entry.level))
        .title_style(theme::header())
        .border_style(theme::accent());
    let inner = block.inner(area);
    frame.render_widget(Clear, area);
    frame.render_widget(block, area);

    let [target_area, body, footer] = Layout::vertical([
        Constraint::Length(2),
        Constraint::Min(1),
        Constraint::Length(1),
    ])
    .areas(inner);

    frame.render_widget(
        Paragraph::new(Line::styled(entry.target.clone(), theme::dim())),
        target_area,
    );
    frame.render_widget(
        Paragraph::new(entry.message.clone()).wrap(ratatui::widgets::Wrap { trim: false }),
        body,
    );
    frame.render_widget(
        Paragraph::new(Line::styled("esc close", theme::dim())).alignment(Alignment::Center),
        footer,
    );
}

fn draw_track_info(frame: &mut Frame, tracks: &[TrackItem], cursor: usize, scroll: usize) {
    let Some(track) = tracks.get(cursor.min(tracks.len().saturating_sub(1))) else {
        return;
    };
    let width = 92.min(frame.area().width.saturating_sub(4)).max(48);
    let height = 24.min(frame.area().height.saturating_sub(2)).max(10);
    let area = centered(frame.area(), width, height);
    let title = if tracks.len() > 1 {
        format!(" Track info — {}/{} ", cursor + 1, tracks.len())
    } else {
        " Track info ".to_string()
    };

    let block = Block::bordered()
        .title(title)
        .title_style(theme::header())
        .border_style(theme::accent());
    let inner = block.inner(area);
    frame.render_widget(Clear, area);
    frame.render_widget(block, area);

    let [body, footer] = Layout::vertical([Constraint::Min(1), Constraint::Length(1)]).areas(inner);
    let lines = track_info_lines(track);
    let max_scroll = lines.len().saturating_sub(usize::from(body.height));
    frame.render_widget(
        Paragraph::new(lines)
            .wrap(Wrap { trim: false })
            .scroll((scroll.min(max_scroll) as u16, 0)),
        body,
    );

    let hint = if tracks.len() > 1 {
        "j/k scroll · h/left previous · l/right next · esc close"
    } else {
        "j/k scroll · esc close"
    };
    frame.render_widget(
        Paragraph::new(Line::styled(hint, theme::dim())).alignment(Alignment::Center),
        footer,
    );
}

fn track_info_lines(track: &TrackItem) -> Vec<Line<'static>> {
    vec![
        field("ID", track.id.to_string()),
        field("Title", track.title.clone()),
        field("Artists", artist_refs(&track.artists)),
        field("Featured artists", artist_refs(&track.featured_artists)),
        field("Release", release_label(track)),
        field("Release ID", track.release_id.to_string()),
        field("Disc", opt_display(track.disc_number)),
        field("Track number", opt_display(track.track_number)),
        field(
            "Duration",
            format!(
                "{} ({:.2}s)",
                track.duration_label(),
                track.duration_seconds
            ),
        ),
        field("Audio format", opt_string(track.audio_format.clone())),
        field(
            "Bitrate",
            opt_map(track.audio_bitrate, |v| format!("{v} kbps")),
        ),
        field(
            "Sample rate",
            opt_map(track.audio_sample_rate, |v| {
                format!("{:.1} kHz", f64::from(v) / 1000.0)
            }),
        ),
        field(
            "Bit depth",
            opt_map(track.audio_bit_depth, |v| format!("{v} bit")),
        ),
        field("File size", file_size(track.file_size_bytes)),
        field("Plays", track.play_count.to_string()),
        field("File path", empty_dash(&track.file_path)),
        field("Cover path", opt_string(track.cover_path.clone())),
    ]
}

fn field(label: &'static str, value: String) -> Line<'static> {
    Line::from(vec![
        Span::styled(format!("{label:<18}"), theme::dim()),
        Span::raw(value),
    ])
}

fn artist_refs(items: &[ArtistRef]) -> String {
    if items.is_empty() {
        return "—".to_string();
    }
    items
        .iter()
        .map(|artist| format!("{} ({})", artist.name, artist.id))
        .collect::<Vec<_>>()
        .join(", ")
}

fn release_label(track: &TrackItem) -> String {
    let mut label = empty_dash(&track.release_title);
    if let Some(year) = track.release_year {
        label.push_str(&format!(" ({year})"));
    }
    label
}

fn empty_dash(value: &str) -> String {
    if value.trim().is_empty() {
        "—".to_string()
    } else {
        value.to_string()
    }
}

fn opt_string(value: Option<String>) -> String {
    value
        .filter(|value| !value.trim().is_empty())
        .unwrap_or_else(|| "—".to_string())
}

fn opt_display<T: std::fmt::Display>(value: Option<T>) -> String {
    opt_map(value, |value| value.to_string())
}

fn opt_map<T>(value: Option<T>, format: impl FnOnce(T) -> String) -> String {
    value.map(format).unwrap_or_else(|| "—".to_string())
}

fn file_size(value: Option<i64>) -> String {
    value
        .map(|bytes| format!("{:.1} MB ({} bytes)", bytes as f64 / 1_048_576.0, bytes))
        .unwrap_or_else(|| "—".to_string())
}

fn draw_picker(frame: &mut Frame, state: &AppState, track_title: &str, cursor: usize) {
    let options = addable_playlists(state);
    let loading = !matches!(&state.playlists.list, Some(Loadable::Ready(_)));
    let rows = options.len() + 1;
    let height = (rows as u16 + 4)
        .min(frame.area().height.saturating_sub(2))
        .max(6);
    let area = centered(frame.area(), 44, height);

    let block = Block::bordered()
        .title(" Add to playlist ")
        .title_style(theme::header())
        .border_style(theme::accent());
    let inner = block.inner(area);
    frame.render_widget(Clear, area);
    frame.render_widget(block, area);

    let [list_area, _, footer] = Layout::vertical([
        Constraint::Min(1),
        Constraint::Length(1),
        Constraint::Length(1),
    ])
    .areas(inner);

    let mut lines: Vec<Line> = vec![Line::styled("+ New playlist…", theme::accent())];
    if loading {
        lines.push(Line::styled("loading playlists…", theme::dim()));
    } else if options.is_empty() {
        lines.push(Line::styled("no playlists yet", theme::dim()));
    } else {
        for (_, title) in &options {
            lines.push(Line::raw(title.clone()));
        }
    }
    let visible = usize::from(list_area.height.max(1));
    let first = cursor
        .saturating_sub(visible / 2)
        .min(lines.len().saturating_sub(visible));
    for (index, line) in lines.into_iter().enumerate().skip(first).take(visible) {
        let row = Rect {
            x: list_area.x,
            y: list_area.y + (index - first) as u16,
            width: list_area.width,
            height: 1,
        };
        frame.render_widget(Paragraph::new(line), row);
        if index == cursor {
            frame.buffer_mut().set_style(row, theme::tab_active());
        }
    }

    frame.render_widget(
        Paragraph::new(Line::styled(
            format!("♪ {track_title} · enter add · esc close"),
            theme::dim(),
        ))
        .alignment(Alignment::Center),
        footer,
    );
}

fn draw_name_entry(frame: &mut Frame, input: &crate::app::input::LineEdit, busy: bool) {
    let area = centered(frame.area(), 44, 7);
    let block = Block::bordered()
        .title(" New playlist ")
        .title_style(theme::header())
        .border_style(theme::accent());
    let inner = block.inner(area);
    frame.render_widget(Clear, area);
    frame.render_widget(block, area);

    let [field, _, footer] = Layout::vertical([
        Constraint::Length(3),
        Constraint::Length(1),
        Constraint::Length(1),
    ])
    .areas(inner);

    let name_block = Block::bordered()
        .title("Name")
        .border_style(theme::accent());
    let name_inner = name_block.inner(field);
    frame.render_widget(name_block, field);
    let spans = super::line_edit_spans(input, usize::from(name_inner.width));
    frame.render_widget(Paragraph::new(Line::from(spans)), name_inner);

    let hint = if busy {
        Line::styled("creating…", theme::accent())
    } else {
        Line::styled("enter create · esc back", theme::dim())
    };
    frame.render_widget(Paragraph::new(hint).alignment(Alignment::Center), footer);
}

fn centered(area: Rect, width: u16, height: u16) -> Rect {
    let [rect] = Layout::horizontal([Constraint::Length(width.min(area.width))])
        .flex(Flex::Center)
        .areas(area);
    let [rect] = Layout::vertical([Constraint::Length(height.min(area.height))])
        .flex(Flex::Center)
        .areas(rect);
    rect
}