clauth 0.5.0

//! Fallback tab — master-detail, mirroring the Config layout. Left: the ordered
//! chain (plus a trailing `+ add` row), cursor = `❯`, color = active. Right: the
//! selected member's rotation card (position, a 5h gauge with a threshold tick,
//! headroom, next hop) plus inline rows — a threshold stepper and a remove row —
//! or, on `+ add`, a candidate picker. Editing happens in place: ⏎ on the left
//! drops focus into the right pane, `+` / `-` step the threshold (or ⏎ on it to
//! type a value), ⏎ on remove arms then confirms. No popups.

use ratatui::Frame;
use ratatui::layout::{Constraint, Direction, Layout, Rect};
use ratatui::style::{Color, Modifier, Style};
use ratatui::text::{Line, Span};
use ratatui::widgets::Paragraph;

use super::super::app::{
    App, ChainItemKind, FALLBACK_ROWS, FallbackFocus, FallbackRow, InputState, chain_candidates,
    chain_items,
};
use super::super::theme;
use super::panes::{
    SELECTOR_WIDTH, draw_selector_list, highlight_row, name_color, section_box, select_line,
};
use crate::fallback::{DEFAULT_THRESHOLD, threshold_for};
use crate::profile::AppConfig;

/// Cells in the detail-pane gauges. Wide enough to read a threshold tick.
const GAUGE_W: usize = 22;
/// Padded key column width for the detail rows, matching the Config tab.
const KEY_W: usize = 11;

pub(super) fn draw(frame: &mut Frame<'_>, area: Rect, app: &App) {
    let cols = Layout::default()
        .direction(Direction::Horizontal)
        .constraints([Constraint::Length(SELECTOR_WIDTH), Constraint::Min(20)])
        .split(area);

    let chain_focused = app.fallback_focus == FallbackFocus::Chain;
    draw_chain_selector(frame, cols[0], app, chain_focused);
    draw_chain_detail(frame, cols[1], app);
}

/// Left pane: the ordered chain members plus a trailing `+ add` row. Color marks
/// the active account; the cursor rides on `❯` only while this pane has focus.
fn draw_chain_selector(frame: &mut Frame<'_>, area: Rect, app: &App, focused: bool) {
    let items = chain_items(app);
    let cfg = app.config();
    let sel = app.chain_cursor.min(items.len().saturating_sub(1));
    draw_selector_list(frame, area, "chain", focused, sel, |w| {
        items
            .iter()
            .enumerate()
            .map(|(row, item)| {
                let selected = row == sel;
                let line = match item {
                    ChainItemKind::Member(i) => {
                        let name = cfg
                            .state
                            .fallback_chain
                            .get(*i)
                            .cloned()
                            .unwrap_or_default();
                        let style = name_color(cfg.is_active(&name));
                        // Cursor + ordinal share the leading span so the name
                        // lands at spans[1] — the item `highlight_row` bolds.
                        let rail = if selected {
                            Span::styled(format!("❯ {:>2}  ", i + 1), theme::accent())
                        } else {
                            Span::styled(format!("  {:>2}  ", i + 1), theme::faint())
                        };
                        Line::from(vec![rail, Span::styled(name, style)])
                    }
                    ChainItemKind::Add => {
                        let arrow = if selected {
                            Span::styled("❯ ", theme::accent())
                        } else {
                            Span::raw("  ")
                        };
                        Line::from(vec![arrow, Span::styled("    + add", theme::accent())])
                    }
                };
                select_line(line, selected, focused, w)
            })
            .collect()
    });
}

/// Right pane: the member rotation card + inline rows, the add-candidate picker
/// on the `+ add` row, or an empty-chain explainer.
fn draw_chain_detail(frame: &mut Frame<'_>, area: Rect, app: &App) {
    let detail_focused = app.fallback_focus == FallbackFocus::Detail;
    let inner_w = section_box("", detail_focused).inner(area).width as usize;
    let items = chain_items(app);
    let selected = items
        .get(app.chain_cursor.min(items.len().saturating_sub(1)))
        .copied();

    // Each arm acquires the `config` guard only for as long as it needs it. The
    // `Add` arm must NOT hold it — `add_detail` re-locks `config` (via
    // `chain_candidates`), and the mutex is non-reentrant, so holding it here
    // would deadlock the whole render loop on the `+ add` row.
    let (title, lines): (String, Vec<Line<'static>>) = match selected {
        Some(ChainItemKind::Member(i)) => {
            let cfg = app.config();
            let chain_len = cfg.state.fallback_chain.len();
            let name = cfg.state.fallback_chain.get(i).cloned().unwrap_or_default();
            let lines = member_detail(
                &cfg,
                &name,
                i,
                chain_len,
                detail_focused,
                app.fallback_detail_cursor,
                app.fallback_armed_remove,
                app.fallback_threshold_draft.as_ref(),
                inner_w,
            );
            (name, lines)
        }
        Some(ChainItemKind::Add) => (
            "add to chain".to_string(),
            add_detail(app, detail_focused, inner_w),
        ),
        None => ("chain".to_string(), empty_detail()),
    };

    let block = section_box(&title, detail_focused);
    let inner = block.inner(area);
    frame.render_widget(block, area);
    frame.render_widget(Paragraph::new(lines).style(theme::base()), inner);
}

/// The member rotation card: position + active state, a 5h gauge with a
/// threshold tick, the headroom, the next hop, then the inline threshold
/// stepper / editor and remove rows. Caret + edit affordances appear only when
/// the right pane holds focus; keybind cues live in the footer.
#[allow(clippy::too_many_arguments)]
fn member_detail(
    cfg: &AppConfig,
    name: &str,
    index: usize,
    chain_len: usize,
    focused: bool,
    row_cursor: usize,
    armed_remove: bool,
    editing: Option<&InputState>,
    width: usize,
) -> Vec<Line<'static>> {
    let Some(profile) = cfg.find(name) else {
        return vec![Line::from(Span::styled(
            "account no longer exists — remove it from the chain",
            theme::danger(),
        ))];
    };

    let threshold = threshold_for(profile);
    let pct = profile
        .usage
        .as_ref()
        .and_then(|u| u.five_hour.as_ref())
        .map(|w| w.utilization);
    let active = cfg.is_active(name);
    let cursor = row_cursor.min(FALLBACK_ROWS.len() - 1);

    let mut lines: Vec<Line<'static>> = Vec::new();

    // Position + active state.
    lines.push(Line::from(vec![
        Span::styled(kv_key("position"), theme::faint()),
        Span::styled(format!("#{} of {chain_len}", index + 1), theme::muted()),
        if active {
            Span::styled("   ● active", theme::orange())
        } else {
            Span::raw("")
        },
    ]));
    lines.push(Line::from(""));

    // 5h gauge with a threshold tick.
    lines.push(Line::from(Span::styled("5h utilization", theme::label())));
    lines.push(Line::from(gauge_with_tick(pct, Some(threshold))));
    let (figure, figure_style) = match pct {
        Some(v) => {
            let headroom = (threshold - v).max(0.0);
            (
                format!("{v:.0}% used · {headroom:.0}% until rotate"),
                Style::default().fg(health_color(v, threshold)),
            )
        }
        None => ("no usage data yet".to_string(), theme::faint()),
    };
    lines.push(Line::from(Span::styled(figure, figure_style)));
    lines.push(Line::from(""));

    // Where rotation flows when this member crosses its threshold.
    if chain_len > 1 {
        let next = (index + 1) % chain_len;
        let next_name = cfg
            .state
            .fallback_chain
            .get(next)
            .cloned()
            .unwrap_or_default();
        let arrow = if next == 0 {
            Span::styled("↺ wraps to ", theme::orange())
        } else {
            Span::styled("→ next ", theme::accent())
        };
        lines.push(Line::from(vec![
            arrow,
            Span::styled(next_name, theme::dim()),
        ]));
    } else {
        lines.push(Line::from(Span::styled(
            "only member — rotation has nowhere to go",
            theme::faint(),
        )));
    }
    lines.push(Line::from(""));

    // Inline rows: threshold stepper / editor, the chain-global wrap-off toggle,
    // then remove. The caret + interactivity only render while the right pane
    // holds focus.
    let wrap_off = cfg.state.wrap_off;
    for (i, row) in FALLBACK_ROWS.iter().enumerate() {
        let selected = focused && i == cursor;
        let row_editing = if *row == FallbackRow::Threshold {
            editing
        } else {
            None
        };
        let line = detail_row(
            *row,
            selected,
            threshold,
            armed_remove,
            wrap_off,
            row_editing,
        );
        lines.push(if selected {
            highlight_row(line, width)
        } else {
            line
        });
        // Meaning tooltip under the focused row (keybind cues live in the footer).
        if selected && row_editing.is_none() {
            let tip = match row {
                FallbackRow::Threshold => Some("rotate to next account when 5h usage reaches this"),
                FallbackRow::WrapOff => Some("what to do once every member is over its threshold"),
                FallbackRow::Remove => None,
            };
            if let Some(tip) = tip {
                lines.push(Line::from(vec![
                    Span::styled("  └ ", theme::faint()),
                    Span::styled(tip, theme::faint()),
                ]));
            }
        }
    }
    lines
}

/// One member detail row: the threshold stepper / editor, the chain-global
/// wrap-off toggle, or the danger remove row. `editing` is `Some` only for the
/// threshold row while it's typed into.
fn detail_row(
    row: FallbackRow,
    selected: bool,
    threshold: f64,
    armed_remove: bool,
    wrap_off: bool,
    editing: Option<&InputState>,
) -> Line<'static> {
    let arrow = if selected {
        Span::styled("❯ ", theme::accent())
    } else {
        Span::raw("  ")
    };
    match row {
        FallbackRow::WrapOff => {
            let pad = KEY_W.saturating_sub("when spent".len()).max(1);
            // Spell out the action, not a mode name: the chosen branch reads as
            // a sentence so "off" is never shown as a bare, confusing value.
            let (value, style) = if wrap_off {
                ("switch off all accounts", theme::orange())
            } else {
                ("stay on last account", theme::accent())
            };
            Line::from(vec![
                arrow,
                Span::styled(
                    format!("when spent{}", " ".repeat(pad)),
                    Style::default().fg(theme::TEXT),
                ),
                Span::styled(value.to_string(), style),
            ])
        }
        FallbackRow::Threshold => {
            let pad = KEY_W.saturating_sub("threshold".len()).max(1);
            let mut spans = vec![
                arrow,
                Span::styled(
                    format!("threshold{}", " ".repeat(pad)),
                    Style::default().fg(theme::TEXT),
                ),
            ];
            match editing {
                Some(input) => {
                    spans.extend(value_caret(input));
                    spans.push(Span::styled("%", theme::faint()));
                }
                None => {
                    spans.push(Span::styled(format!("{threshold:.0}%"), theme::accent()));
                    if (threshold - DEFAULT_THRESHOLD).abs() > f64::EPSILON {
                        spans.push(Span::styled(
                            format!("   default: {DEFAULT_THRESHOLD:.0}%"),
                            theme::faint(),
                        ));
                    }
                }
            }
            Line::from(spans)
        }
        FallbackRow::Remove => {
            let label = if armed_remove {
                "remove from chain — ⏎ again to confirm".to_string()
            } else {
                "remove from chain".to_string()
            };
            Line::from(vec![arrow, Span::styled(label, theme::danger())])
        }
    }
}

/// The typed threshold value with a block caret over a sunken input strip,
/// matching the Config tab's inline text edit.
fn value_caret(input: &InputState) -> Vec<Span<'static>> {
    let (head, tail) = input.value.split_at(input.cursor.min(input.value.len()));
    let caret_style = Style::default()
        .fg(theme::TEXT)
        .bg(theme::ACCENT)
        .add_modifier(Modifier::BOLD);
    let body = Style::default().fg(theme::TEXT).bg(theme::BG_SUNKEN);
    let mut tail_iter = tail.chars();
    let caret = tail_iter.next().unwrap_or(' ').to_string();
    let after: String = tail_iter.collect();
    vec![
        Span::styled(head.to_string(), body),
        Span::styled(caret, caret_style),
        Span::styled(after, body),
    ]
}

/// The `+ add` detail: an explainer plus the candidate picker. The caret only
/// renders while the right pane holds focus.
fn add_detail(app: &App, focused: bool, width: usize) -> Vec<Line<'static>> {
    let candidates = chain_candidates(app);
    let mut lines: Vec<Line<'static>> = vec![
        Line::from(Span::styled(
            "add an account to the rotation",
            theme::muted(),
        )),
        Line::from(""),
        Line::from(Span::styled(
            "clauth auto-switches off a member when its 5h window crosses the",
            theme::dim(),
        )),
        Line::from(Span::styled(
            "member's threshold, moving to the next account in the chain.",
            theme::dim(),
        )),
        Line::from(""),
    ];

    if candidates.is_empty() {
        lines.push(Line::from(Span::styled(
            "every account is already in the chain",
            theme::faint(),
        )));
        return lines;
    }

    // Blurred: explainer only. The candidate rows (with caret) appear once the
    // right pane takes focus; the footer carries the keybind cue.
    if !focused {
        return lines;
    }

    let cursor = app
        .fallback_detail_cursor
        .min(candidates.len().saturating_sub(1));
    for (i, name) in candidates.iter().enumerate() {
        let selected = i == cursor;
        let arrow = if selected {
            Span::styled("❯ ", theme::accent())
        } else {
            Span::raw("  ")
        };
        let line = Line::from(vec![
            arrow,
            Span::styled(name.clone(), Style::default().fg(theme::TEXT)),
        ]);
        lines.push(if selected {
            highlight_row(line, width)
        } else {
            line
        });
    }
    lines
}

fn empty_detail() -> Vec<Line<'static>> {
    vec![
        Line::from(Span::styled("chain is empty", theme::muted())),
        Line::from(""),
        Line::from(Span::styled(
            "create an account first, then add it to the chain.",
            theme::dim(),
        )),
    ]
}

/// `GAUGE_W`-cell bar over 0..100 with the fill colored by headroom against the
/// threshold and a `┊` tick drawn at the threshold position.
fn gauge_with_tick(pct: Option<f64>, threshold: Option<f64>) -> Vec<Span<'static>> {
    let value = pct.unwrap_or(0.0).clamp(0.0, 100.0);
    let fill = ((value / 100.0) * GAUGE_W as f64).round() as usize;
    let fill = fill.min(GAUGE_W);
    let tick = threshold.map(|t| {
        (((t.clamp(0.0, 100.0) / 100.0) * GAUGE_W as f64).round() as usize).min(GAUGE_W - 1)
    });
    let fill_color = match (pct, threshold) {
        (Some(v), Some(t)) => health_color(v, t),
        (Some(_), None) => theme::ACCENT,
        _ => theme::TEXT_FAINT,
    };

    let mut spans = vec![Span::raw("[")];
    for i in 0..GAUGE_W {
        if Some(i) == tick {
            spans.push(Span::styled("┊", Style::default().fg(theme::TEXT)));
        } else if i < fill {
            spans.push(Span::styled("█", Style::default().fg(fill_color)));
        } else {
            spans.push(Span::styled("░", Style::default().fg(theme::LINE_STRONG)));
        }
    }
    spans.push(Span::raw("]"));
    spans
}

/// 5h headroom against the member's own threshold: green with room, yellow as
/// it nears, pink once it crosses — the point clauth rotates off it.
fn health_color(pct: f64, threshold: f64) -> Color {
    if pct >= threshold {
        theme::DANGER
    } else if pct >= threshold * 0.8 {
        theme::WARNING
    } else {
        theme::SUCCESS
    }
}

/// Pad a detail key to a fixed gutter so values line up.
fn kv_key(key: &str) -> String {
    let pad = KEY_W.saturating_sub(key.chars().count()).max(1);
    format!("{key}{}", " ".repeat(pad))
}