//! All rendering. The app is two screens (file browser, editor) plus
//! centered modal popups.

use ratatui::layout::{Alignment, Constraint, Layout, Rect};
use ratatui::style::{Color, Modifier, Style};
use ratatui::text::{Line, Span, Text};
use ratatui::widgets::{
    Block, BorderType, Borders, Clear, Gauge, List, ListItem, ListState, Paragraph, Wrap,
};
use ratatui::Frame;

use crate::app::{App, Modal, Screen};
use crate::ffmpeg;
use crate::ops::FieldValue;

// Catppuccin Macchiato (https://catppuccin.com), blue accent.
const ACCENT: Color = Color::Rgb(0x8a, 0xad, 0xf4); // blue
const ON_ACCENT: Color = Color::Rgb(0x24, 0x27, 0x3a); // base, for text on accent
const TEXT: Color = Color::Rgb(0xca, 0xd3, 0xf5); // text
const SUBTLE: Color = Color::Rgb(0xa5, 0xad, 0xcb); // subtext0
const DIM: Color = Color::Rgb(0x6e, 0x73, 0x8d); // overlay0
const YELLOW: Color = Color::Rgb(0xee, 0xd4, 0x9f);
const GREEN: Color = Color::Rgb(0xa6, 0xda, 0x95);
const RED: Color = Color::Rgb(0xed, 0x87, 0x96);
const LAVENDER: Color = Color::Rgb(0xb7, 0xbd, 0xf8);

pub fn draw(f: &mut Frame, app: &mut App) {
    match app.screen {
        Screen::Browser => draw_browser(f, app),
        Screen::Editor => draw_editor(f, app),
    }
    // Modals render on top of whichever screen is active.
    let modal_ptr = app.modal.take();
    if let Some(modal) = &modal_ptr {
        draw_modal(f, app, modal);
    }
    app.modal = modal_ptr;
}

fn title_block(title: impl Into<String>) -> Block<'static> {
    Block::default()
        .borders(Borders::ALL)
        .border_type(BorderType::Rounded)
        .title(Span::styled(
            format!(" {} ", title.into()),
            Style::default().fg(ACCENT).add_modifier(Modifier::BOLD),
        ))
}

fn key_hint(line: &[(&str, &str)]) -> Line<'static> {
    let mut spans = Vec::new();
    for (key, what) in line {
        spans.push(Span::styled(
            format!(" {} ", key),
            Style::default().fg(ON_ACCENT).bg(ACCENT),
        ));
        spans.push(Span::styled(format!(" {}  ", what), Style::default().fg(SUBTLE)));
    }
    Line::from(spans)
}

// ---------------------------------------------------------------------------
// Browser

fn draw_browser(f: &mut Frame, app: &mut App) {
    let [header, main, footer] =
        Layout::vertical([Constraint::Length(3), Constraint::Min(0), Constraint::Length(1)])
            .areas(f.area());

    let banner = Paragraph::new(Line::from(vec![
        Span::styled("lazyff ", Style::default().fg(ACCENT).add_modifier(Modifier::BOLD)),
        Span::styled("— pick a video or audio file to edit", Style::default().fg(SUBTLE)),
    ]))
    .block(title_block(app.cwd.display().to_string()));
    f.render_widget(banner, header);

    let items: Vec<ListItem> = app
        .entries
        .iter()
        .map(|e| {
            if e.is_dir {
                ListItem::new(Line::from(vec![
                    Span::raw("  "),
                    Span::styled("\u{1f4c1} ", Style::default()),
                    Span::styled(e.name.clone(), Style::default().fg(LAVENDER)),
                    Span::raw("/"),
                ]))
            } else {
                let marked = app.marks.contains(&app.cwd.join(&e.name));
                ListItem::new(Line::from(vec![
                    if marked {
                        Span::styled("\u{2713} ", Style::default().fg(GREEN))
                    } else {
                        Span::raw("  ")
                    },
                    Span::raw("\u{1f3ac} "),
                    Span::raw(e.name.clone()),
                ]))
            }
        })
        .collect();

    let title = if app.marks.is_empty() {
        "Files".to_string()
    } else {
        format!("Files \u{2014} {} marked for batch", app.marks.len())
    };
    let mut block = title_block(title);
    if let Some(err) = &app.browser_error {
        block = block.title_bottom(Line::from(Span::styled(
            format!(" {} ", err.lines().next().unwrap_or("error")),
            Style::default().fg(RED),
        )));
    }
    let list = List::new(items)
        .block(block)
        .highlight_style(Style::default().bg(ACCENT).fg(ON_ACCENT).add_modifier(Modifier::BOLD))
        .highlight_symbol(" ");
    f.render_stateful_widget(list, main, &mut app.browser_state);

    let hints = key_hint(&[
        ("\u{2191}\u{2193}", "move"),
        ("Enter", "open"),
        ("Space", "mark for batch"),
        ("u", "unmark all"),
        ("Backspace", "up a folder"),
        ("q", "quit"),
    ]);
    f.render_widget(Paragraph::new(hints), footer);
}

// ---------------------------------------------------------------------------
// Editor

fn draw_editor(f: &mut Frame, app: &mut App) {
    let [main, footer] =
        Layout::vertical([Constraint::Min(0), Constraint::Length(1)]).areas(f.area());
    let [left, right] =
        Layout::horizontal([Constraint::Percentage(52), Constraint::Percentage(48)]).areas(main);

    // Left: list of queued operations.
    let input_name = match app.files.as_slice() {
        [] => String::new(),
        [(path, _)] => crate::app::file_name(path),
        files => format!("{} files (batch)", files.len()),
    };

    let items: Vec<ListItem> = if app.ops.is_empty() {
        vec![ListItem::new(Text::from(vec![
            Line::raw(""),
            Line::styled("  No edits yet.", Style::default().fg(DIM)),
            Line::styled("  Press 'a' to add one (trim, resize, compress...).", Style::default().fg(DIM)),
        ]))]
    } else {
        app.ops
            .iter()
            .enumerate()
            .map(|(i, op)| {
                ListItem::new(Line::from(vec![
                    Span::styled(format!(" {}. ", i + 1), Style::default().fg(DIM)),
                    Span::styled(
                        format!("{:<15} ", op.kind.name()),
                        Style::default().fg(YELLOW),
                    ),
                    Span::raw(op.summary()),
                ]))
            })
            .collect()
    };
    let list = List::new(items)
        .block(title_block(format!("Edits \u{2014} {}", input_name)))
        .highlight_style(Style::default().bg(ACCENT).fg(ON_ACCENT).add_modifier(Modifier::BOLD));
    f.render_stateful_widget(list, left, &mut app.op_state);

    // Right: media info on top, command preview below.
    let [info_area, cmd_area] =
        Layout::vertical([Constraint::Length(9), Constraint::Min(0)]).areas(right);

    if let Some((path, m)) = app.files.first() {
        let mut lines = vec![
            info_line("Container", &m.format),
            info_line("Duration", &ffmpeg::fmt_clock(m.duration)),
            info_line("Size", &ffmpeg::fmt_size(m.size_bytes)),
        ];
        if app.is_batch() {
            lines.insert(0, info_line("First file", &crate::app::file_name(path)));
            lines.truncate(4);
            lines.push(info_line(
                "Batch",
                &format!("+ {} more file(s)", app.files.len() - 1),
            ));
        }
        if let (Some(c), Some(w), Some(h)) = (&m.video_codec, m.width, m.height) {
            let fps = m.fps.map(|f| format!(" @ {:.2} fps", f)).unwrap_or_default();
            lines.push(info_line("Video", &format!("{} {}\u{d7}{}{}", c, w, h, fps)));
        } else {
            lines.push(info_line("Video", "none (audio file)"));
        }
        lines.push(info_line(
            "Audio",
            m.audio_codec.as_deref().unwrap_or("none"),
        ));
        f.render_widget(
            Paragraph::new(lines).block(title_block("Media info")),
            info_area,
        );
    }

    // Command preview, rebuilt every frame (cheap) so it always matches.
    if let Some((input, media)) = app.files.first() {
        let built = ffmpeg::build(input, &app.ops, &app.stem_for(input), media);
        let mut text = Text::default();
        text.push_line(Line::styled(
            format!("Output: {}", built.output.display()),
            Style::default().fg(GREEN),
        ));
        if app.is_batch() {
            text.push_line(Line::styled(
                format!(
                    "These edits run on all {} files (first one shown)",
                    app.files.len()
                ),
                Style::default().fg(YELLOW),
            ));
        }
        text.push_line(Line::raw(""));
        for line in ffmpeg::preview_string(&built).lines() {
            let style = if line.starts_with('#') {
                Style::default().fg(DIM)
            } else {
                Style::default().fg(TEXT)
            };
            text.push_line(Line::styled(line.to_string(), style));
        }
        if !built.notes.is_empty() {
            text.push_line(Line::raw(""));
            for n in &built.notes {
                text.push_line(Line::styled(
                    format!("\u{2139} {}", n),
                    Style::default().fg(YELLOW),
                ));
            }
        }
        f.render_widget(
            Paragraph::new(text)
                .wrap(Wrap { trim: false })
                .block(title_block("Command (what lazyff will run)")),
            cmd_area,
        );
    }

    let hints = key_hint(&[
        ("a", "add edit"),
        ("Enter", "change"),
        ("d", "delete"),
        ("s", "save recipe"),
        ("l", "load recipe"),
        ("o", "output"),
        ("r", "run!"),
        ("Esc", "files"),
        ("q", "quit"),
    ]);
    f.render_widget(Paragraph::new(hints), footer);
}

fn info_line(label: &str, value: &str) -> Line<'static> {
    Line::from(vec![
        Span::styled(format!(" {:<10} ", label), Style::default().fg(DIM)),
        Span::raw(value.to_string()),
    ])
}

// ---------------------------------------------------------------------------
// Modals

fn draw_modal(f: &mut Frame, app: &mut App, modal: &Modal) {
    match modal {
        Modal::AddOp { selected } => {
            let kinds = app.available_kinds();
            let title = if app.has_video() {
                "Add an edit  (Enter to choose, Esc to cancel)"
            } else {
                "Add an edit \u{2014} audio file  (Enter to choose, Esc to cancel)"
            };
            let area = centered(f.area(), 64, kinds.len() as u16 + 2);
            f.render_widget(Clear, area);
            let items: Vec<ListItem> = kinds
                .iter()
                .map(|k| {
                    ListItem::new(Line::from(vec![
                        Span::styled(
                            format!(" {:<15} ", k.name()),
                            Style::default().fg(YELLOW),
                        ),
                        Span::styled(k.blurb(), Style::default().fg(SUBTLE)),
                    ]))
                })
                .collect();
            let mut state = ListState::default();
            state.select(Some(*selected));
            let list = List::new(items)
                .block(title_block(title))
                .highlight_style(
                    Style::default().bg(ACCENT).fg(ON_ACCENT).add_modifier(Modifier::BOLD),
                );
            f.render_stateful_widget(list, area, &mut state);
        }

        Modal::EditOp { field, op, .. } => {
            let area = centered(f.area(), 66, op.fields.len() as u16 + 4);
            f.render_widget(Clear, area);
            let mut lines = vec![Line::raw("")];
            for (i, fld) in op.fields.iter().enumerate() {
                let selected = i == *field;
                let marker = if selected { " \u{25b8} " } else { "   " };
                let label_style = if selected {
                    Style::default().fg(ACCENT).add_modifier(Modifier::BOLD)
                } else {
                    Style::default().fg(SUBTLE)
                };
                let value = match &fld.value {
                    FieldValue::Choice { options, selected: s } => {
                        format!("\u{25c2} {} \u{25b8}", options[*s].label)
                    }
                    FieldValue::Text(s) => {
                        if selected {
                            format!("{}\u{2581}", s)
                        } else if s.is_empty() {
                            "(empty)".to_string()
                        } else {
                            s.clone()
                        }
                    }
                };
                lines.push(Line::from(vec![
                    Span::raw(marker.to_string()),
                    Span::styled(format!("{:<28}", fld.label), label_style),
                    Span::styled(
                        value,
                        if selected {
                            Style::default().fg(TEXT).add_modifier(Modifier::BOLD)
                        } else {
                            Style::default().fg(SUBTLE)
                        },
                    ),
                ]));
            }
            lines.push(Line::raw(""));
            lines.push(Line::styled(
                "  \u{2191}\u{2193} field \u{2502} \u{2190}\u{2192} change \u{2502} type to edit \u{2502} Enter save \u{2502} Esc cancel",
                Style::default().fg(DIM),
            ));
            f.render_widget(
                Paragraph::new(lines).block(title_block(op.kind.name())),
                area,
            );
        }

        Modal::Output { text } => {
            let (title, hint) = if app.is_batch() {
                (
                    "Output suffix (added to each file's name)",
                    "  (extension is chosen automatically)",
                )
            } else {
                ("Output file name", "  (extension is chosen automatically)")
            };
            draw_text_input(f, title, text, hint);
        }

        Modal::SaveRecipe { text } => {
            draw_text_input(
                f,
                "Save these edits as a recipe \u{2014} name?",
                text,
                "  (apply later with 'l')",
            );
        }

        Modal::LoadRecipe { selected } => {
            let area = centered(f.area(), 56, app.recipes.len() as u16 + 4);
            f.render_widget(Clear, area);
            let items: Vec<ListItem> = app
                .recipes
                .iter()
                .map(|r| {
                    ListItem::new(Line::from(vec![
                        Span::styled(
                            format!(" {:<30}", r.name),
                            Style::default().fg(YELLOW),
                        ),
                        Span::styled(
                            format!("{} edit(s)", r.ops.len()),
                            Style::default().fg(SUBTLE),
                        ),
                    ]))
                })
                .collect();
            let mut state = ListState::default();
            state.select(Some(*selected));
            let list = List::new(items)
                .block(
                    title_block("Apply a recipe").title_bottom(Line::from(Span::styled(
                        " Enter apply \u{2502} d delete \u{2502} Esc cancel ",
                        Style::default().fg(DIM),
                    ))),
                )
                .highlight_style(
                    Style::default().bg(ACCENT).fg(ON_ACCENT).add_modifier(Modifier::BOLD),
                );
            f.render_stateful_widget(list, area, &mut state);
        }

        Modal::Running => {
            let area = centered(f.area(), 64, 9);
            f.render_widget(Clear, area);
            let block = title_block("Encoding\u{2026}  (Esc to cancel)");
            let inner = block.inner(area);
            f.render_widget(block, area);
            f.render_widget(Clear, inner);

            if let Some(rs) = &app.run {
                let [head_area, gauge_area, info_area, err_area] = Layout::vertical([
                    Constraint::Length(1),
                    Constraint::Length(3),
                    Constraint::Length(1),
                    Constraint::Min(0),
                ])
                .areas(inner);

                let job = &rs.jobs[rs.job_idx];
                let mut head = String::new();
                if rs.jobs.len() > 1 {
                    head.push_str(&format!("File {}/{}: ", rs.job_idx + 1, rs.jobs.len()));
                }
                head.push_str(&job.input_name);
                if job.built.passes.len() > 1 {
                    head.push_str(&format!(
                        "   \u{2014} pass {}/{}",
                        rs.pass_idx + 1,
                        job.built.passes.len()
                    ));
                }
                f.render_widget(Paragraph::new(head).alignment(Alignment::Center), head_area);

                let expected = job.built.expected_duration;
                let ratio = if expected > 0.0 {
                    (rs.secs / expected).clamp(0.0, 1.0)
                } else {
                    0.0
                };
                let gauge = Gauge::default()
                    .gauge_style(Style::default().fg(ACCENT))
                    .ratio(ratio)
                    .label(format!("{:.0}%", ratio * 100.0));
                f.render_widget(gauge, gauge_area.inner(ratatui::layout::Margin::new(1, 1)));

                let speed = if rs.speed.is_empty() { "?".into() } else { rs.speed.clone() };
                let info = Paragraph::new(format!(
                    "{} / {}   speed {}",
                    ffmpeg::fmt_clock(rs.secs),
                    ffmpeg::fmt_clock(expected),
                    speed
                ))
                .alignment(Alignment::Center);
                f.render_widget(info, info_area);

                if !rs.errors.is_empty() {
                    let last = rs.errors.last().cloned().unwrap_or_default();
                    f.render_widget(
                        Paragraph::new(Line::styled(last, Style::default().fg(RED)))
                            .wrap(Wrap { trim: true }),
                        err_area,
                    );
                }
            }
        }

        Modal::Done { success, title, message } => {
            let wanted = message.lines().count() as u16 + 4;
            let area = centered(f.area(), 70, wanted.min(f.area().height.saturating_sub(4)));
            f.render_widget(Clear, area);
            let color = if *success { GREEN } else { RED };
            let block = Block::default()
                .borders(Borders::ALL)
                .border_type(BorderType::Rounded)
                .border_style(Style::default().fg(color))
                .title(Span::styled(
                    format!(" {} ", title),
                    Style::default().fg(color).add_modifier(Modifier::BOLD),
                ))
                .title_bottom(Line::from(Span::styled(
                    " Enter to close ",
                    Style::default().fg(DIM),
                )));
            f.render_widget(
                Paragraph::new(message.clone()).wrap(Wrap { trim: false }).block(block),
                area,
            );
        }
    }
}

fn draw_text_input(f: &mut Frame, title: &str, text: &str, hint: &str) {
    let area = centered(f.area(), 60, 5);
    f.render_widget(Clear, area);
    let lines = vec![
        Line::raw(""),
        Line::from(vec![
            Span::raw("  "),
            Span::styled(
                format!("{}\u{2581}", text),
                Style::default().fg(TEXT).add_modifier(Modifier::BOLD),
            ),
            Span::styled(hint.to_string(), Style::default().fg(DIM)),
        ]),
        Line::styled("  Enter save \u{2502} Esc cancel", Style::default().fg(DIM)),
    ];
    f.render_widget(
        Paragraph::new(lines).block(title_block(title.to_string())),
        area,
    );
}

fn centered(area: Rect, width: u16, height: u16) -> Rect {
    let w = width.min(area.width.saturating_sub(2));
    let h = height.min(area.height.saturating_sub(2));
    Rect {
        x: area.x + (area.width.saturating_sub(w)) / 2,
        y: area.y + (area.height.saturating_sub(h)) / 2,
        width: w,
        height: h,
    }
}