datui_cli/

keys.rs

//! The key registry: every key of every screen, in one table.
//!
//! Each [`Key`] is what is typed, a short label (for hints), a one-line description
//! (the in-app help), an optional longer description (the manpage and the docs),
//! and the key the help's Enter presses for it. Keys sit in task [`Group`]s on a
//! [`Screen`]; [`GLOBAL`] holds the keys every screen takes.
//!
//! What shows keys reads them from here: the help overlay `?` opens in `datui-lib`,
//! `docs/reference/keyboard-shortcuts.md` ([`render_markdown`]) and `datui-keys(7)`.
//! A key added to the app is an entry here; a test in `datui-lib` presses each
//! entry's key in its screen and fails when nothing takes it.

/// Where the keys are typed: one in-app help screen each.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub enum Context {
    Table,
    Home,
    Documentation,
    Query,
    Find,
    GoToColumn,
    Inspector,
    Info,
    ValueCounts,
    SortFilter,
    PivotMelt,
    Chart,
    Describe,
    Distribution,
    DistributionDetail,
    Correlation,
    CorrelationDetail,
    DataQuality,
    Export,
    Copy,
    Views,
    FormatPicker,
    Retype,
    Combine,
    TablePicker,
    Sample,
    Hex,
}

/// One screen's keys.
#[derive(Debug, Clone, Copy)]
pub struct Screen {
    pub context: Context,
    /// Its heading in the help, the reference and the manpage: `Table`.
    pub title: &'static str,
    /// How the screen is reached, as markdown.
    pub reached: &'static str,
    /// Its keys, by task, in the order the help shows them.
    pub groups: &'static [Group],
}

/// Keys that do one kind of task: `Explore`, `Shape`, `Analyze`, `Output`, or a
/// screen's own (`Fields`, `Picker`).
#[derive(Debug, Clone, Copy)]
pub struct Group {
    pub name: &'static str,
    pub keys: &'static [Key],
}

/// One key, or a few that do one thing in turn (`n / N`).
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct Key {
    /// What is typed, as the help writes it: `↑ / ↓ (j/k)`, `Ctrl+O`, `(type)`.
    pub keys: &'static str,
    /// A word or two for a hint beside the key: `Filter`, `Next match`.
    pub label: &'static str,
    /// One line: the in-app help, and the man page and docs without [`Key::more`].
    pub line: &'static str,
    /// The whole description, where it says more than the line: the manpage and the
    /// docs print it in place of the line.
    pub more: Option<&'static str>,
    pub run: Run,
}

/// What Enter on a key's help line presses, in the screen help was opened from.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Run {
    /// The first key of [`Key::keys`].
    First,
    /// This key, as [`chord`] reads it.
    Key(&'static str),
    /// Nothing: typing, the mouse, a range of digits.
    Never,
}

/// A key entry: `keys`, a hint `label` and the help's `line`.
pub const fn k(keys: &'static str, label: &'static str, line: &'static str) -> Key {
    Key {
        keys,
        label,
        line,
        more: None,
        run: Run::First,
    }
}

impl Key {
    /// With the whole description for the manpage and the docs.
    pub const fn more(self, more: &'static str) -> Self {
        Key {
            more: Some(more),
            ..self
        }
    }

    /// Enter in the help presses `spec` rather than the first key.
    pub const fn run(self, spec: &'static str) -> Self {
        Key {
            run: Run::Key(spec),
            ..self
        }
    }

    /// Enter in the help presses nothing for this entry.
    pub const fn no_run(self) -> Self {
        Key {
            run: Run::Never,
            ..self
        }
    }

    /// The description the manpage and the docs print.
    pub fn long(&self) -> &'static str {
        self.more.unwrap_or(self.line)
    }

    /// The key Enter on this line presses, if any.
    pub fn action(&self) -> Option<Chord> {
        match self.run {
            Run::First => chord(first_key(self.keys)),
            Run::Key(spec) => chord(spec),
            Run::Never => None,
        }
    }
}

/// A key as the app receives it, without the terminal library: `datui-lib` turns it
/// into a key event.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct Chord {
    pub code: Code,
    pub ctrl: bool,
    pub alt: bool,
    pub shift: bool,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Code {
    Char(char),
    Enter,
    Esc,
    Tab,
    BackTab,
    Backspace,
    Delete,
    Insert,
    Up,
    Down,
    Left,
    Right,
    PageUp,
    PageDown,
    Home,
    End,
    F(u8),
}

/// Every key a `keys` text names, in order: `↑ / ↓ (j/k)` is ↑, ↓, j and k. Text that
/// is not a key (`(type)`, `Click`) names none.
pub fn chords(keys: &str) -> Vec<Chord> {
    let spaced = keys.replace(['(', ')'], " / ");
    spaced
        .split(" / ")
        .flat_map(|part| part.split(", "))
        .flat_map(|part| part.split(" or "))
        .map(str::trim)
        .flat_map(|token| {
            // `PgUp/PgDn`, `h/l`; a lone `/` is the slash key.
            if token.len() > 1 && token.contains('/') {
                token
                    .split('/')
                    .filter(|t| !t.is_empty())
                    .collect::<Vec<_>>()
            } else {
                vec![token]
            }
        })
        .filter_map(chord)
        .collect()
}

/// The first key a `keys` text names: `↑` of `↑ / ↓ (j/k)`, `Ctrl+D` of
/// `Ctrl+D/Ctrl+U`.
pub fn first_key(keys: &str) -> &str {
    let mut end = keys.len();
    for sep in [" / ", ", ", " (", " or ", " "] {
        if let Some(at) = keys.find(sep)
            && at > 0
        {
            end = end.min(at);
        }
    }
    let first = &keys[..end];
    // `PgUp/PgDn`, `Ctrl+D/Ctrl+U`; a lone `/` is the slash key.
    match first.find('/') {
        Some(at) if at > 0 && first.len() > 1 => &first[..at],
        _ => first,
    }
}

/// Read one key: `j`, `G`, `Enter`, `Ctrl+O`, `Shift+Tab`, `F1`, `↑`. `None` for text
/// that is not one key.
pub fn chord(spec: &str) -> Option<Chord> {
    let mut chord = Chord {
        code: Code::Esc,
        ctrl: false,
        alt: false,
        shift: false,
    };
    let mut rest = spec;
    loop {
        if let Some(r) = rest.strip_prefix("Ctrl+").filter(|r| !r.is_empty()) {
            chord.ctrl = true;
            rest = r;
        } else if let Some(r) = rest.strip_prefix("Alt+").filter(|r| !r.is_empty()) {
            chord.alt = true;
            rest = r;
        } else if let Some(r) = rest.strip_prefix("Shift+").filter(|r| !r.is_empty()) {
            chord.shift = true;
            rest = r;
        } else {
            break;
        }
    }
    chord.code = match rest {
        "Enter" => Code::Enter,
        "Esc" => Code::Esc,
        "Tab" if chord.shift => Code::BackTab,
        "Tab" => Code::Tab,
        "Space" => Code::Char(' '),
        "Backspace" => Code::Backspace,
        "Delete" | "Del" => Code::Delete,
        "Insert" => Code::Insert,
        "PgUp" | "PageUp" => Code::PageUp,
        "PgDn" | "PageDown" => Code::PageDown,
        "Home" => Code::Home,
        "End" => Code::End,
        "↑" | "↑↓" => Code::Up,
        "↓" => Code::Down,
        "←" | "←→" => Code::Left,
        "→" => Code::Right,
        _ => {
            let mut chars = rest.chars();
            match (chars.next(), chars.next()) {
                // Ctrl+O is the letter o with Ctrl; a capital alone comes with Shift,
                // as a terminal reports it.
                (Some(c), None) if c.is_ascii_alphabetic() && chord.ctrl => {
                    Code::Char(c.to_ascii_lowercase())
                }
                (Some(c), None) if !c.is_whitespace() => {
                    if c.is_ascii_uppercase() {
                        chord.shift = true;
                    }
                    Code::Char(c)
                }
                (Some('F'), Some(_)) => Code::F(rest[1..].parse().ok().filter(|n| *n <= 12)?),
                _ => return None,
            }
        }
    };
    Some(chord)
}

/// The keys every screen takes. Every screen's help lists them last.
pub const GLOBAL: Group = Group {
    name: "Everywhere",
    keys: &[
        k("? / F1", "Help", "This screen's keys (F1 in text fields)")
            .more("This screen's keys. In a text field ? types, and F1 opens the help")
            .run("F1"),
        k("Ctrl+O", "Home", "The home screen; abandons a load")
            .more("The home screen, on the dataset left, its filter kept and selected (typing replaces it); abandons a load"),
        k(
            "Ctrl+Q / Ctrl+C",
            "Quit",
            "Quit (Ctrl+C in a text field too)",
        )
        .more("Quit from anywhere; Ctrl+C quits from a text field too, where Alt+W copies"),
        k("Click a field", "Act", "Focus a form's field and act as Space")
            .more("Focus a form's field and act as Space: a checkbox flips, a choice steps, a picker opens, a button runs; a text field takes the cursor. A row of a list (a sort, a filter, a column) takes focus on the first click and acts on the second. A click on a picker's line chooses it, on a tab switches to it, and on a key in the footer presses it. A click outside a dialog does nothing. The mouse is the terminal's with display.mouse = false (or --mouse false); in most terminals Shift+drag selects text either way")
            .no_run(),
        k("Right-click a field", "Back", "Step a choice back, as ← does; else focus it").no_run(),
    ],
};

/// The keys of the help overlay itself, for its footer and the reference.
pub const HELP: Group = Group {
    name: "Help",
    keys: &[
        k("↑ / ↓ (j/k)", "Move", "Move between the keys"),
        k("Enter", "Run", "Close the help and press the key")
            .more("Close the help and press the key on the line, where help was opened"),
        k("/", "Filter", "Narrow to the keys whose text matches"),
        k("Esc", "Close", "Clear the filter, then close"),
    ],
};

/// Where the whole reference is, the help's last line.
pub const REFERENCE_URL: &str =
    "https://derekwisong.github.io/datui/reference/keyboard-shortcuts.html";

/// The q language in a few lines, for the query screen's help and `datui-query(7)`:
/// an example and what it shows.
pub const Q_SUMMARY: &[(&str, &str)] = &[
    (
        "select [cols] [by groups] [where conds]",
        "Each part optional",
    ),
    (
        "select a, b where a > 10, b < 5",
        "In where, , is and; | is or",
    ),
    (
        "select avg price, n:count id by region",
        "Aggregate by group",
    ),
    (
        "total:a+b  col[\"first name\"]",
        "Name a column; a name with spaces",
    ),
    ("1/c+a is 1/(c+a)", "Right to left: 100 < (a+b)*2"),
    (
        "date.year  2024.01.31  city.contains[\"York\"]",
        "Accessors and dates",
    ),
    (
        "name in [\"Ann\", \"Bo\"]  item like \"*ham*\"",
        "Membership and patterns",
    ),
];

/// The analysis tools' sample keys, the same on each.
const SAMPLE_KEYS: &[Key] = &[
    k("s", "Sample", "Choose the sample every tool reads").more(
        "Choose the sample every tool reads: which rows, how they are picked, how many (typed, like 50000, 50k or 2m), the seed. Enter applies the form",
    ),
    k(
        "v",
        "Sample rows",
        "View the sample's rows as a table; Esc comes back",
    ),
    k(
        "r",
        "Resample",
        "Draw another sample (when the result is a sample)",
    ),
    k("a", "All rows", "Read every row instead, after confirming"),
    k("t", "New rows", "Read again with rows that arrived since").more(
        "While following a file, read again with the rows that arrived since the results were read",
    ),
];

/// Every screen, as the reference lists them.
pub const SCREENS: &[Screen] = &[
    Screen {
        context: Context::Table,
        title: "Table",
        reached: "Where a dataset opens.",
        groups: &[
            Group {
                name: "Explore",
                keys: &[
                    k("↑ / ↓ (j/k)", "Move", "Move the row cursor"),
                    k("← / → (h/l)", "Column", "Move the column cursor")
                        .more("Move the column cursor, frozen columns included; the columns scroll only when it would leave the screen"),
                    k("Shift+← / Shift+→", "Page columns", "A page of columns left or right")
                        .more("A page of columns left or right, the cursor on the page's first column"),
                    k("{ / }", "First, last", "First column, last column"),
                    k("PgUp / PgDn", "Page", "A page up or down (Ctrl+B / Ctrl+F too)"),
                    k("Ctrl+D / Ctrl+U", "Half page", "Half a page down or up"),
                    k("Home / End", "Top, end", "First or last row (G = End)"),
                    k(":", "Command line", "Go to a row, or run SQL or q")
                        .more("The command line: digits go to that row (the prefix says row:), anything else runs as SQL or q, as the prefix says; Ctrl+T switches. With a query in effect it opens on the query's text"),
                    k("g", "Go to column", "Go to a column by name"),
                    k("/ (f)", "Find", "Find text, a regex, or letters in order")
                        .more("Find text, a regex, or letters in order in the view; matches on screen light up as you type, and Enter takes the cursor, column cursor and all, to the first at or after its row. f opens it too"),
                    k("n / N", "Next", "Next or previous match")
                        .more("Next / previous match from the cursor's cell, wrapping round the view"),
                    k("Enter", "Drill", "Drill down to a group's rows, or inspect")
                        .more("On a row of a by query or a SQL GROUP BY, drill down to its rows (Esc comes back); elsewhere, inspect the row"),
                    k("Space", "Inspect", "Inspect the row: every field, whole")
                        .more("Inspect the row: every field, each value whole and exact (Esc or Space closes)"),
                ],
            },
            Group {
                name: "Shape",
                keys: &[
                    k("[ / ]", "Sort", "Sort by the cursor's column, up or down")
                        .more("Sort by the cursor's column, [ ascending and ] descending, replacing the sort in effect; the same key again on that column removes it. The s sidebar adds secondary sorts"),
                    k("s", "Sort & Filter", "Sort & Filter sidebar, on the cursor's column")
                        .more("Open the Sort & Filter sidebar (tabs: Columns, Filters), on the cursor's column"),
                    k("+ / -", "Filter", "Keep (+) or drop (-) rows with this cell's value")
                        .more("Filter on the cursor's cell: + keeps the rows with its value, - drops them (a null cell: the nulls). Each adds a filter to the Sort & Filter sidebar, joined with \"and\"; the value is the cell's exactly as stored"),
                    k("r", "Reverse", "Reverse the sort, or the row order")
                        .more("Reverse sort order (sorted columns carry a direction mark in the header); with no sort, reverse the row order"),
                    k("H / L", "Move column", "Move the cursor's column left or right")
                        .more("Move the cursor's column one place left or right, the cursor with it; a frozen column moves among the frozen ones. R puts the order back"),
                    k("p", "Pivot & Melt", "Pivot or melt"),
                    k("S", "Sample", "Draw a sample into memory; the view works on it")
                        .more("Draw a sample of the source into memory: the step under the query, filters and sort, which then run over it. The rows show as they arrive (Esc stops, keeping them); the footer says sample 100,000 of 36.8M. Analysis, charts and export read the sample. S again edits it; Method No sample, or R, takes it away"),
                    k("R", "Reset", "Clear query, filters, sort, layout, view")
                        .more("Reset table: clear the sample, query, filters, sort, column order, hidden columns and widths, frozen columns, pivot/melt, drill-down and the applied view"),
                ],
            },
            Group {
                name: "Analyze",
                keys: &[
                    k("F", "Counts", "Value counts of the cursor's column")
                        .more("Value counts of the cursor's column: each value's rows, percent and a bar, with a summary"),
                    k("a", "Analysis", "Describe, distributions, correlation, quality")
                        .more("Open Analysis. In a Data Quality evidence drill a is disabled; Esc returns to the observation"),
                    k("c", "Chart", "Chart the view"),
                    k("i", "Info", "Schema, resources, partitions, notes")
                        .more("Open the Info panel (tabs: Schema, Resources, Partitions, Notes). H on its Schema tab reads a CSV's first row as data, or as column names"),
                ],
            },
            Group {
                name: "Output",
                keys: &[
                    k("e", "Export", "Export the view to a file"),
                    k("y", "Copy", "Copy a cell, row, view or table")
                        .more("Copy to the clipboard (cell, row, view or table); a cell is the cursor's"),
                    k("v", "Views", "The saved views list"),
                    k("V", "Apply view", "Apply the best-matching view")
                        .more("Apply the best-matching view (or open the list)"),
                ],
            },
            Group {
                name: "Display",
                keys: &[
                    k("#", "Row numbers", "Row numbers on or off")
                        .more("Row numbers on or off: each row's place in the source, kept through a sort or a filter (a text file's line numbers). On for text and logs; display.row_numbers sets it"),
                    k(",", "Grouping", "Number formatting (digit grouping) on or off"),
                    k("D", "Types", "The type row under the headers on or off"),
                    k("< / >", "Width", "The cursor's column 4 cells narrower or wider"),
                    k("= / w", "Fit, auto", "Fit the column to the rows on screen; automatic")
                        .more("Fit the cursor's column to the rows on screen; w puts it back to automatic width"),
                    k("b", "Format spec", "Read a binary file with another format spec")
                        .more("A binary file read through a format spec: read it again with another spec. Clears the query, filters and sort"),
                    k("T", "Table", "Open another table of the file")
                        .more("A file of several tables (a workbook's worksheets, a database's tables, a format spec's record types, a Hugging Face cache's splits): pick another to open in place of this one, as --table names it. Clears the query, filters and sort; a saved view for the table applies. On a file of one table, says so"),
                    k("t", "Follow", "Follow the file as it grows")
                        .more("Follow the file as it grows (CSV, TSV, PSV, NDJSON). Reads it again, so the query, filters and sort are cleared; while following, t pauses and resumes, and Esc stops"),
                ],
            },
            Group {
                name: "Go",
                keys: &[
                    k("q", "Back", "Home when opened from there, else quit")
                        .more("Back to the home screen when the dataset was opened from it; otherwise quit"),
                    k("Q", "Quit", "Quit"),
                    k("Esc", "Back", "Leave a drill-down; stop a find, sample, follow")
                        .more("Leave a drill-down; stop a find, a sample being drawn (its rows so far stay) or a follow"),
                ],
            },
            Group {
                name: "Mouse",
                keys: &[
                    k("Click", "Point", "The cursor to the cell; on a header, its column")
                        .no_run(),
                    k("Double-click", "Enter", "Enter on the row").no_run(),
                    k("Double-click a header", "Sort", "Sort by it: up, down, off, as [ / ] do")
                        .more("Double-click a column's header to sort by it, as [ and ] do: ascending, then descending, then back to no sort, replacing the sort in effect")
                        .no_run(),
                    k("Double-click a header's edge", "Fit", "Fit the column to the rows, as = does")
                        .more("Double-click the gap right of a column's header to fit the column to the rows on screen, as = does; the column cursor moves to it, and nothing is sorted")
                        .no_run(),
                    k("Wheel", "Scroll", "↑ / ↓, three rows a notch")
                        .more("↑ / ↓, three rows a notch; the same in help, the inspector and the sidebars")
                        .no_run(),
                    k("Shift+wheel", "Across", "← / →, the column cursor")
                        .more("← / →, the column cursor (a sideways wheel too)")
                        .no_run(),
                    k("Click a key", "Press", "Press a key the footer shows")
                        .more("Press a key the footer shows; a click on the filters and sort presses s, on query presses :")
                        .no_run(),
                    k("Drag a header", "Move column", "Move the column there, as H / L do")
                        .more("Drag a column's header onto another column to move it there, as H / L do; a rule on the header marks where it lands")
                        .no_run(),
                    k("Drag a header's edge", "Width", "Set the column's width, as < / > do")
                        .more("Drag the gap right of a column's header to set its width by hand, as < / > do, from 4 to 240 cells")
                        .no_run(),
                    k("Right-click", "Menu", "A menu of the keys that act on the cell")
                        .more("Right-click a cell: the cursor goes there and a menu lists the keys that act on it (+, -, F, [, ], y, Space), each with its key. ↑ / ↓ and Enter, or a click, run a line as its key does; Esc or a click elsewhere closes it")
                        .no_run(),
                ],
            },
        ],
    },
    Screen {
        context: Context::Home,
        title: "Home screen",
        reached: "`datui` with no path, or <kbd>Ctrl</kbd>+<kbd>O</kbd> from anywhere.",
        groups: &[
            Group {
                name: "Explore",
                keys: &[
                    k("↑ / ↓", "Move", "Move the selection (Ctrl+P / Ctrl+N too)"),
                    k("Ctrl+↑ / Ctrl+↓", "Section", "Previous or next section"),
                    k("PgUp / PgDn", "Page", "A screenful, stopping at the first and last"),
                    k("Home / End", "First, last", "The first or last row")
                        .more("The first or last row. The filter has no cursor to move: it is edited at its end"),
                    k("← / →", "Fold", "Fold or unfold; → goes inside")
                        .more("Fold or unfold a section; → on a directory or a file of tables goes inside it, and on a file a format spec reads as record types lists them, one row each"),
                    k("Space", "Fold", "Fold the section (types once filtering)")
                        .more("While the filter is empty: fold or unfold the section header under the cursor. With a filter typed, it types"),
                    k("Tab", "Sort", "Cycle the sort")
                        .more("Cycle the sort; the footer names the order in effect when it has room"),
                ],
            },
            Group {
                name: "Go",
                keys: &[
                    k("Enter", "Open", "What the footer names: Open, Inside, Look")
                        .more("What the footer says on this row: \"Open all\" reads a whole directory as one table, \"Inside\" steps into it, \"Open\" loads a file, \"Look\" finds out first. A catalog bookmark, indented under its dataset, opens whole. On a section header, fold or unfold it; on the More row, show the rest; on the hidden-files row, show them"),
                    k("Backspace", "Up", "Delete a filter character, or up a level")
                        .more("Delete a filter character; on an empty filter, up a level (from a bucket, back to its cloud source; from the top of a catalog's remote dataset, back here)"),
                    k("Esc", "Back", "Path prompt, filter, directory, then the table")
                        .more("Back out one layer: the path prompt, the filter (onto the first dataset), the directory (back to the row it was entered from), then to the open table"),
                ],
            },
            Group {
                name: "Find",
                keys: &[
                    k("(type)", "Filter", "Narrow by name or column, fuzzy")
                        .more("Narrow by name or column; fuzzy, so \"sal\" finds \"sales\". What you open often ranks first. Typing also searches below the directory you are inside and the listed bucket names; matches appear under \"Found\"")
                        .no_run(),
                    k("~", "Path", "Type a path or URL (on an empty filter)")
                        .more("While the filter is empty: type a path or URL by hand. The list shows the directory being typed, narrowed by the name after the last /. The prompt is a plain editor: characters, Backspace, Ctrl+U clears, The first name that matches is picked. Tab completes the one name left or what the names share, or a name picked further down; ↑ / ↓ pick a name, and ↑ from the first takes the path as typed; Enter opens the picked name or the typed path: a file opens, a directory is gone inside; Esc closes. s3://, gs:// and az:// complete from buckets and prefixes already known. With a filter typed, ~ types into it"),
                    k("Ctrl+U", "Clear", "Clear the filter or path input"),
                    k("Ctrl+R", "Refresh", "List again what is on screen"),
                ],
            },
            Group {
                name: "Manage",
                keys: &[
                    k("Ctrl+A", "All files", "Show or hide files datui cannot read")
                        .more("Show or hide files datui cannot read; inside a SQLite database, its internal tables"),
                    k("Ctrl+X", "Hex", "The file under the cursor as bytes")
                        .more("Show the local file under the cursor as bytes, in the hex view, whatever datui would read it as"),
                    k("Ctrl+D", "Catalog", "Add the row to catalog.toml; on its rows, forget it")
                        .more("Add the dataset or directory under the cursor to catalog.toml, listed under My datasets; on a row from catalog.toml, forget it. A heading stands for the directory it lists. Only catalog.toml is written; another catalog is hidden with home.hide"),
                    k("Ctrl+E", "Docs", "The row's documentation, full screen")
                        .more("Open the Documentation view of a catalog row, of a place inside one, or of a file whose format spec documents it: description, publisher, license, links, record types, columns with units and value legends, bookmarks. A catalog's description, link and column notes stand over the spec's. Ctrl+E here is not readline's end of line: the filter is edited at its end"),
                    k("Delete", "Forget", "Forget a recent, place or catalog.toml row; hide")
                        .more("Forget the highlighted recent entry, or a whole place after confirming, or a row from catalog.toml, or hide a cloud source. On the Example datasets heading, hide them until datui cache clear, after confirming"),
                    k("Shift+Delete", "Forget all", "Forget every recent entry, after confirming"),
                ],
            },
            Group {
                name: "Mouse",
                keys: &[
                    k("Click", "Select", "Select the row; double-click is Enter").no_run(),
                    k("Wheel", "Scroll", "Move the selection three rows")
                        .more("Move the selection three rows, stopping at the ends")
                        .no_run(),
                ],
            },
        ],
    },
    Screen {
        context: Context::Documentation,
        title: "Documentation",
        reached: "<kbd>Ctrl</kbd>+<kbd>E</kbd> on the home screen, on a catalog row or a file a format spec documents.",
        groups: &[Group {
            name: "Read",
            keys: &[
                k("↑ / ↓ (j/k)", "Move", "Move the cursor a line"),
                k("PgUp / PgDn", "Page", "A page"),
                k("g / G", "Ends", "The first or last line (Home / End too)"),
                k("Enter / Space / →", "Values", "Open or close the column's value legend")
                    .more("Open or close the value legend of the column under the cursor: a catalog's values, or a spec's enum"),
                k("o", "Open", "Open the line's link in the browser, after asking")
                    .more("Open the link on the cursor's line in the system browser. Only http and https links open, and only after a question showing the whole URL (Enter opens, Esc does not). Off over SSH or without a display: y copies the link instead"),
                k("y", "Copy", "Copy the line's link or value, whole")
                    .more("Copy the link or value on the cursor's line, whole, however it is cut on screen"),
                k("Esc / q / ←", "Back", "Back to the home screen"),
            ],
        }],
    },
    Screen {
        context: Context::Query,
        title: "Command line",
        reached: "<kbd>:</kbd> at the table.",
        groups: &[
            Group {
                name: "Run",
                keys: &[
                    k("(digits)", "Row", "Digits go to that row (row: shows it)")
                        .more("Digits alone go to that row, and the prefix says row: (:0 Enter is the top)")
                        .no_run(),
                    k("Enter", "Run", "Go to the row, or run the query")
                        .more("Go to the row, or run the query as the prefix says, sql: or q:. Reopened with a query in effect, the line holds its text, selected: typing replaces it, arrows edit it"),
                    k("Ctrl+J", "Run", "Run, the same as Enter"),
                    k("Ctrl+T", "Language", "SQL or q; the line keeps its text")
                        .more("Switch between SQL and q, keeping what is typed; the choice is remembered. [query] default_mode sets the first"),
                    k("Esc", "Close", "Close"),
                ],
            },
            Group {
                name: "Edit",
                keys: &[
                    k("Tab", "Complete", "Complete a column name (SQL: or df)")
                        .more("Complete a column name, or df in SQL; again for the next match. The line under the input lists the names that fit"),
                    k("Alt+Enter", "New line", "SQL: start a new line"),
                    k("↑ / ↓", "History", "Earlier and later queries (Ctrl+P / Ctrl+N)")
                        .more("Earlier and later queries from the history (Ctrl+P / Ctrl+N too; SQL and q keep their own). In SQL over several lines, they move between lines first"),
                    k("Ctrl+U / Ctrl+K", "Delete", "Delete to the start or end of the line"),
                    k("Ctrl+Z / Ctrl+R", "Undo", "Undo, redo"),
                ],
            },
        ],
    },
    Screen {
        context: Context::Find,
        title: "Find",
        reached: "<kbd>/</kbd> (or <kbd>f</kbd>) at the table.",
        groups: &[
            Group {
                name: "Find",
                keys: &[
                    k("(text)", "Pattern", "Text, a regex, or letters in order")
                        .more("What to find: text (any case until a capital is typed), a regex with Ctrl+R, or letters in order with Ctrl+T. Matches in the rows on screen light up as you type, and the line says how many are on screen")
                        .no_run(),
                    k("Enter", "Next", "Go to the first match at or after the row")
                        .more("Find: the cursor, column cursor and all, goes to the first match at or after its row, reading past the rows on hand when it must (the footer counts the rows read; Esc stops). On an empty field, clear the find"),
                    k("Ctrl+G", "Keep matches", "Keep only the rows that match, as a filter")
                        .more("Keep only the rows with a match, as a filter: the footer and the Sort & Filter sidebar show it, and removing it there (or R) brings the rows back"),
                    k("Ctrl+R", "Regex", "Regex on or off"),
                    k("Ctrl+T", "Letters in order", "Letters in order on or off: smth finds Smith"),
                    k("Ctrl+L", "Column", "Only the cursor's column, or every column")
                        .more("Only the column cursor's column, or every column shown"),
                    k("↑ / ↓", "History", "Earlier patterns (Ctrl+P / Ctrl+N too)"),
                    k("Esc", "Cancel", "Cancel"),
                ],
            },
            Group {
                // Keys of the table, not the prompt: Enter here would type them.
                name: "At the table",
                keys: &[
                    k("n / N", "Next", "Next or previous match")
                        .more("Next / previous match from the cursor's cell. Past the last match the find comes round to the first, and the footer says so. Each one typed while a find reads runs in turn; Esc stops them all").no_run(),
                    k("/", "Find again", "Find again, the last pattern ready to edit").no_run(),
                    k("Esc", "Clear", "Clear the find (or stop one still reading)").no_run(),
                ],
            },
        ],
    },
    Screen {
        context: Context::GoToColumn,
        title: "Go to column",
        reached: "<kbd>g</kbd> at the table.",
        groups: &[Group {
            name: "Go",
            keys: &[
                k("(type)", "Narrow", "Narrow to the names that contain it").no_run(),
                k("↑ / ↓", "Move", "Move"),
                k("Enter", "Go", "Move the column cursor to it")
                    .more("Go. The column cursor moves to it. A column already whole on screen stays where it is; another becomes the first after the frozen ones, or lands on the last page when it is there"),
                k("Backspace", "Delete", "Delete a character (Ctrl+W a word, Ctrl+U all)"),
                k("Esc", "Close", "Close without moving"),
            ],
        }],
    },
    Screen {
        context: Context::Inspector,
        title: "Inspector",
        reached: "<kbd>Space</kbd> at the table.",
        groups: &[
            Group {
                name: "Fields",
                keys: &[
                    k("↑ / ↓ (j/k)", "Move", "Move between fields"),
                    k("Home / End", "First, last", "First and last field"),
                    k("PgUp / PgDn", "Page", "A page of fields"),
                    k("← / → (h/l)", "Row", "Previous and next row")
                        .more("Previous and next row; the table's cursor moves with it"),
                    k("Tab / Shift+Tab", "Value", "Into the value, to scroll and find in it")
                        .more("Into the value, to scroll and find in it. Nothing moves: the panes are split by what they hold, not by where the cursor is"),
                    k("Enter", "Open", "Open a struct, list or JSON; read a field")
                        .more("On a group's row, its rows, as at the table. Else open a struct, a list, or text holding a JSON object or array; or read a field the table's rows do not hold (hidden and binary columns)"),
                    k("r", "Read", "On a group's row, read a field the rows lack")
                        .more("On a group's row, read a field the rows do not hold"),
                    k("/", "Find", "Find a field by name, then by value")
                        .more("Find a field by name, then by value: type to narrow, Enter or ↓ keeps the list narrowed, Esc clears it"),
                    k("f", "Nulls", "Nulls shown or hidden (comparing: only diffs)")
                        .more("Nulls: shown or hidden (null and empty fields); comparing, only the fields that differ"),
                    k("s", "Order", "Order: the table's, A-Z, or nulls last"),
                    k("c", "Compare", "Compare with the next row, or the pinned one")
                        .more("Compare: a column for the next row, or the pinned one"),
                    k("m", "Pin", "Pin this row to compare others with; again to unpin"),
                    k("Esc / Space", "Close", "Close; Esc clears a find, then Compare, first")
                        .more("Close. Esc backs out one level at a time: a find first, then Compare, then the inspector"),
                ],
            },
            Group {
                name: "Output",
                keys: &[
                    k("y", "Copy", "Copy the value as its view shows it"),
                    k("Y", "Copy row", "Copy the whole row as one JSON object"),
                    k("e", "View", "The value's next view, where it has more than one"),
                    k("w", "Wrap", "Word wrap or hard wrap for long text"),
                    k("o", "Open", "Open the value in another program"),
                ],
            },
            Group {
                name: "Value",
                keys: &[
                    k("↑ / ↓ (j/k)", "Scroll", "Scroll a line"),
                    k("PgUp / PgDn", "Page", "Scroll a page"),
                    k("Home / End", "Top, end", "Top and end, however long the value")
                        .more("Top and end, at once however long the value"),
                    k("/", "Find", "Find in the value; n and N go on")
                        .more("Find in the value; n and N go to the next and last place"),
                    k("e, w, y, o", "As fields", "As in the fields"),
                    k("Esc / Tab", "Fields", "Back to the fields; Esc clears a find first")
                        .more("Back to the fields (Shift+Tab too); Esc clears a find first"),
                ],
            },
            Group {
                name: "Nested",
                keys: &[
                    k("Enter / → (l)", "Open", "Open the focused item"),
                    k("Tab / Shift+Tab", "Value", "Into the item's value; not in an empty level"),
                    k("Esc / ← (h)", "Up", "Up a level; at the row, Esc closes"),
                    k("y", "Copy", "Copy the item: text, or JSON indented")
                        .more("Copy the focused item: text as itself, a JSON object or array indented"),
                ],
            },
        ],
    },
    Screen {
        context: Context::Info,
        title: "Info panel",
        reached: "<kbd>i</kbd> at the table.",
        groups: &[Group {
            name: "Panel",
            keys: &[
                k("← / → (h/l)", "Tab", "Previous or next tab (Shift+Tab / Tab too)")
                    .more("Previous or next tab, from anywhere in the panel; Shift+Tab and Tab do the same. The panel is a viewer, not a form: its body always has the keys"),
                k("↑ / ↓ (j/k)", "Move", "Move the cursor, or scroll the list")
                    .more("Schema, Notes or Documentation tab: move the cursor. Model, Audio, MIDI, Metadata and format tabs: scroll the list"),
                k("PgUp / PgDn", "Page", "Scroll the list a page")
                    .more("Model, Audio, MIDI, Metadata and format tabs: scroll the list a page"),
                k("Home / End", "Top, end", "The top or the end of the list")
                    .more("Model, Audio, MIDI, Metadata and format tabs: the top or the end of the list"),
                k("Enter", "Take", "Schema: the type; Notes: the offer; a table: open it")
                    .more("Schema tab: change the column's type, with the names and formats a format spec's type takes. Notes tab: take the offer on the note, where it has one. Documentation tab: open or close the value legend of the column under the cursor. Excel or SQLite tab: open the worksheet or table under the cursor in place of this one, as T does"),
                k("o", "Open", "Documentation tab: open the line's link")
                    .more("Documentation tab: open the link on the cursor's line in the system browser. Only http and https links open, and only after a question showing the whole URL. Off over SSH or without a display"),
                k("y", "Copy", "Documentation tab: copy the line's link or value")
                    .more("Documentation tab: copy the link or value on the cursor's line, whole, however it is cut on screen"),
                k("H", "Header", "Schema tab, CSV: first row as data or names")
                    .more("Schema tab, CSV, TSV, PSV: read the first row as data, under column_1, column_2, …; again to read it as column names. Reads the file again, so the query, filters and sort are cleared, and the panel closes"),
                k("c", "Count", "Count every row, where the count is an estimate")
                    .more("A dataset of more files than read.exact_count_files shows a row count estimated from a sample of its footers; c reads every footer for the exact count. The footer shows how far it has got, and Esc at the table stops it"),
                k("x", "Hex", "Show the file's bytes in the hex view"),
                k("Esc / i", "Close", "Close the panel"),
            ],
        }],
    },
    Screen {
        context: Context::ValueCounts,
        title: "Value counts",
        reached: "<kbd>F</kbd> at the table.",
        groups: &[
            Group {
                name: "Explore",
                keys: &[
                    k("↑ / ↓ (j/k)", "Move", "Move"),
                    k("PgUp / PgDn", "Page", "A page"),
                    k("Home / End", "First, last", "First and last row"),
                    k("← / → (h/l)", "Column", "The previous or next column")
                        .more("The previous or next column; the table's column cursor moves with it"),
                    k("Enter", "Drill", "The rows holding the value")
                        .more("The rows holding the value, as a drill-down; Esc there comes back here"),
                    k("s", "Sort", "Sort by count or by value"),
                    k("c", "Histogram", "A number's histogram, or its counts")
                        .more("Between a number column's histogram, binned from the counts, and the listing of its values. A number opens as its histogram"),
                    k("a", "All rows", "Count every row, when the counts are of a sample"),
                    k("t", "New rows", "Count again with the rows that arrived")
                        .more("While following a file, count again with the rows that arrived since; the bar says how many"),
                ],
            },
            Group {
                name: "Output",
                keys: &[
                    k("y", "Copy", "Copy the counts as TSV")
                        .more("Copy the counts as TSV: every value, its count, percent and cumulative percent"),
                    k("e", "Export", "Export the counts to a file"),
                    k("Esc", "Back", "Back to the table")
                        .more("Back to the table; while every row is being counted, stop that and keep the sample"),
                ],
            },
        ],
    },
    Screen {
        context: Context::SortFilter,
        title: "Sort and filter",
        reached: "<kbd>s</kbd> at the table.",
        groups: &[
            Group {
                name: "Sidebar",
                keys: &[
                    k("Tab / Shift+Tab (↑ / ↓)", "Next", "Next or previous field")
                        .more("Next or previous field, wrapping; a field the form does not offer right now is skipped. The arrows move from the moment the dialog opens"),
                    k("← / →", "Change", "Tabs on the tab bar; flip a sort; and/or")
                        .more("On the tab bar: switch Sort & Filter / Columns. On a sort: flip its direction. On a filter: and / or. On a column: step its sort (none, ascending, descending). h/l too"),
                    k("Space", "Act", "Flip a sort, edit a filter, add one")
                        .more("On a sort: flip its direction. On a filter: edit it (column, operator, value). On \"add sort\": pick a column to sort by, last and ascending. On \"add filter\": a new filter, starting on the table's column cursor. On a column: step its sort"),
                    k("Enter", "Apply", "Apply and close, from any row")
                        .more("Apply everything staged and close, from any row (in the filter editor Enter takes the step; Ctrl+J applies)"),
                    k("Ctrl+J", "Apply", "Apply from anywhere, mid-edit too")
                        .more("Apply from anywhere, including mid-edit (the row in progress is saved). Ctrl+Enter does the same, on a terminal that tells it from Enter"),
                    k("Esc", "Cancel", "Close a picker or editor, then the sidebar")
                        .more("Close an open picker or filter editor; otherwise cancel and close, discarding what is staged. Reopening shows what is applied"),
                ],
            },
            Group {
                name: "In effect",
                keys: &[
                    k("[ / ]", "Move", "Move the sort or filter earlier or later")
                        .more("Move the focused sort earlier or later in the sort order, or the focused filter in the list"),
                    k("d / Del", "Remove", "Remove the sort or filter"),
                    k("C", "Clear", "Remove every sort and filter"),
                ],
            },
            Group {
                name: "Columns",
                keys: &[
                    k("(type)", "Narrow", "Narrow the list, with the find field focused")
                        .more("Narrow the column list, when the find field is focused. ↓ from find goes to the list, on the table's column cursor")
                        .no_run(),
                    k("PgUp / PgDn, Home / End", "Page", "A page of columns; the first or last")
                        .more("A page of columns, or the first or last; ↓ stops at the last column"),
                    k("Space", "Sort", "Cycle the sort: none, ascending, descending")
                        .more("Cycle the column's sort: none → ascending → descending (← steps back). Each column carries its own direction"),
                    k("1-9", "Sort place", "Put the column at that place in the sort")
                        .more("Put the column at that place in the sort order; 0 removes it (a digit past the end of the order says so)")
                        .run("1"),
                    k("Del", "Unsort", "Remove the column from the sort"),
                    k("[ / ]", "Sort order", "Earlier or later in the sort order"),
                    k("+ / - (= / _)", "Position", "Move the column's display position"),
                    k("L", "Freeze", "Freeze columns up to this one at the left")
                        .more("Freeze this column and every column up to it at the left edge; on a column already frozen, pull the boundary back"),
                    k("v", "Hide", "Show or hide the column")
                        .more("Show or hide the column (it keeps its place, dimmed)"),
                    k("< / > (, / .)", "Width", "4 cells narrower or wider")
                        .more("Make the column 4 cells narrower or wider. A number column is never narrower than its numbers"),
                    k("f", "Fit", "Fit to the rows on screen")
                        .more("Fit the column to the rows on screen, its name up to the automatic limit"),
                    k("w", "Auto width", "Back to the automatic width"),
                    k("C", "Clear", "Clear staged sort, order, locks, hidden, widths")
                        .more("Clear the staged sort, order, locks, hidden columns and widths"),
                ],
            },
            Group {
                name: "Filter editor",
                keys: &[
                    k("(type)", "Narrow", "Narrow the column or operator list")
                        .more("Narrow the column or operator list. The operators are those the column's type takes")
                        .no_run(),
                    k("Enter", "Next", "Choose the step; from the value, save the row")
                        .more("Pick the column (type to narrow, Enter chooses), the operator the same way, then type the value and Enter saves the row. Tab, → and Space also choose at the column and operator steps; Shift+Tab steps back; ↑ / ↓ move in the lists"),
                    k("Esc", "Back", "End the edit, and only the edit"),
                ],
            },
        ],
    },
    Screen {
        context: Context::PivotMelt,
        title: "Pivot and melt",
        reached: "<kbd>p</kbd> at the table: the form on the left, a live preview of the result on the right (above and below on a narrow terminal).",
        groups: &[
            Group {
                name: "Form",
                keys: &[
                    k("Tab / Shift+Tab (↑ / ↓)", "Next", "Next or previous field")
                        .more("Next or previous field, wrapping; a field the form does not offer right now is skipped. The arrows move from the moment the builder opens"),
                    k("← / →", "Change", "Pivot / Melt on the first row; step a choice")
                        .more("On the first row: switch Pivot and Melt. On the aggregation, strategy or type: the previous or next value. On a single column row: the previous or next column. In a text field: move the cursor. h/l too, outside text fields. The preview follows each change"),
                    k("Space", "Open", "Open a column picker; next value of a choice")
                        .more("On a column row: open its picker, scoped to that row; typing narrows it. On a choice: its next value, wrapping"),
                    k("Enter", "Apply", "Apply the reshape the preview shows")
                        .more("Apply the reshape the preview shows, to the whole view, from any field"),
                    k("Esc", "Close", "Close without applying; stop a pivot")
                        .more("Close without applying; while a pivot is computed, stop it and keep the builder"),
                ],
            },
            Group {
                name: "Picker",
                keys: &[
                    k("(type)", "Narrow", "Narrow the column list").no_run(),
                    k("↑ / ↓", "Move", "Move; typing narrows"),
                    k("Enter", "Choose", "Choose; on a several-choice row, done"),
                    k("Space", "Toggle", "Choose; toggle a column on a several-choice row"),
                    k("Esc", "Back", "Back out of the picker, undoing its toggles")
                        .more("Back out of the picker; the toggles made since it opened are undone (Enter keeps them)"),
                ],
            },
        ],
    },
    Screen {
        context: Context::Chart,
        title: "Chart",
        reached: "<kbd>c</kbd> at the table: a chart chosen from the cursor column's type.",
        groups: &[
            Group {
                name: "Shelves",
                keys: &[
                    k("1-7", "Type", "Chart type, in order: Line to Heatmap")
                        .more("Switch the chart type directly: Line, Scatter, Bar, Histogram, Box, KDE, Heatmap ([ / ] step). The shelves keep what the new type takes. On Rows, digits type a sample size instead")
                        .run("1"),
                    k("[ / ]", "Type", "Previous or next chart type"),
                    k("Tab / Shift+Tab (↑ / ↓)", "Next", "Next or previous row")
                        .more("Next or previous row of the panel, wrapping (j/k too). A shelf the type does not use is dimmed and skipped"),
                    k("Space / Enter", "Act", "Open a shelf's picker, toggle, or step the row")
                        .more("On X, Y or Color: open its picker. On the line under Color: pick the values that get a series, by rows. On an option: toggle it or take its next value. The panel applies as it changes, so Enter acts as Space does, except on Rows: Space switches between Sample and Every row, and Enter reads what the row says"),
                    k("← / → (h/l)", "Change", "Step the type, bucket, aggregate or option")
                        .more("Step the type, the time bucket (day, week, month, quarter, year), the aggregate (count, distinct, sum, mean, median, stdev, quantile, min, max, first, last) and a quantile's percentile, cumulative, bins, range or order; on Rows, switch between Sample and Every row (read on Enter); on a shelf that takes one column, the previous or next column; on the line under Color, turn Other (every value without a series) on or off; flip a toggle"),
                    k("+ / -", "Adjust", "Bins or bandwidth"),
                    k("0-9", "Size", "On Rows: type a sample size, like 50k or 2m")
                        .more("On Rows: type a sample size, like 50000, 50,000, 50k, 250k or 2m. Backspace edits, Enter reads it, Esc puts the row back as it was. A size of at least the table's rows is Every row. Nothing is read until Enter or focus leaves the row")
                        .no_run(),
                    k("g", "Grid", "Grid on or off")
                        .more("Grid on or off at the labeled ticks: Line, Scatter, Histogram, Box and KDE. [analysis] chart_grid sets where it starts"),
                    k("Esc", "Back", "Back to the table")
                        .more("Back to the table; on Rows with a change waiting, put the row back first"),
                ],
            },
            Group {
                name: "Plot",
                keys: &[
                    k("x", "Crosshair", "Line, Scatter: a crosshair reads out the values")
                        .more("Line and Scatter: the plot takes the keys, and a crosshair reads out x and every series' value under the plot. ← / → (h/l) step to the next point or column, Home/End go to the ends; x, Tab or Esc hand the keys back to the panel. A click on the plot puts the crosshair there"),
                    k("e", "Export", "Export the chart to PNG, SVG or PDF")
                        .more("Export the chart to PNG, SVG or PDF, with a title, notes and source. Needs the chart's shelves filled first"),
                    k("t", "New rows", "Draw again with the rows that arrived")
                        .more("While following a file, draw again with the rows that arrived since; the bar says how many"),
                ],
            },
            Group {
                name: "Picker",
                keys: &[
                    k("↑ / ↓", "Move", "Move; typing narrows"),
                    k("Enter / Space", "Choose", "Choose (Y, Color values: Space toggles one)")
                        .more("Choose; on a line or scatter chart's Y and on the Color values, Space toggles one in or out (up to 10, fewer on a terminal of fewer colors)"),
                    k("Tab / Shift+Tab", "Next", "Choose and move to the next or previous row"),
                    k("Esc", "Back", "Back out of the picker alone"),
                ],
            },
            Group {
                name: "Export dialog",
                keys: &[
                    k("Tab / Shift+Tab (↑ / ↓)", "Next", "Path, format, style, size, legend, words")
                        .more("Next or previous field: Path, Format, Style, Size, Width, Height, Legend, the marks (Opacity and Point size for a scatter, Line width for a line, Y from zero for a line), Title, Description, Notes, Source, Byline, Recipe"),
                    k("← / →", "Change", "Step the format, style, size, legend or marks")
                        .more("Step the format (PNG, SVG, PDF), the style (Light, Dark, Transparent), the size (Slide 16:9, Document, Square, Single column, Double column, Custom), the legend (line ends, a corner, off), a scatter's point opacity (Auto, 100%, 50%, 20%) and size (Small, Medium, Large), a line's width (Thin, Normal, Bold), Y from zero, or the recipe (Include, Omit). Typing a width or height makes the size Custom"),
                    k("Ctrl+P / Ctrl+N", "History", "Earlier or later paths in the path field"),
                    k("Enter", "Export", "Export, from anywhere in the dialog")
                        .more("Export, from anywhere in the dialog. A path ending .png, .svg or .pdf takes that format; any other gets the format's extension after it. An existing file asks Overwrite / No, starting on No; ←/→ (h/l) or Tab pick, Enter confirms, and declining returns to the filled dialog"),
                    k("Esc", "Back", "Back to the chart"),
                ],
            },
        ],
    },
    Screen {
        context: Context::Describe,
        title: "Analysis: Describe",
        reached: "<kbd>a</kbd> at the table.",
        groups: &[
            Group {
                name: "Explore",
                keys: &[
                    k("Tab / Shift+Tab", "Focus", "Between the results and the tools"),
                    k("↑ / ↓ (j/k)", "Move", "Rows, or the sidebar's tools"),
                    k("← / → (h/l)", "Scroll", "Scroll the statistics")
                        .more("Scroll the statistics; the header counts those out of view"),
                    k("Home / End", "First, last", "First or last row"),
                    k("PgUp / PgDn", "Page", "A page"),
                    k("Enter", "Open", "Open the sidebar's tool")
                        .more("Open the sidebar's tool and move into its pane. The first run on a dataset starts in the Sample form, where Enter runs it; later tools reuse that sample. Results last until the view changes: closing and reopening shows them again"),
                    k("Esc", "Back", "Cancel a run; the tools; then close")
                        .more("Cancel a run in progress; otherwise from the results back to the tools, and from the tools close the analysis view"),
                ],
            },
            Group {
                name: "Sample",
                keys: SAMPLE_KEYS,
            },
        ],
    },
    Screen {
        context: Context::Distribution,
        title: "Analysis: Distribution",
        reached: "Distribution in the Analysis sidebar.",
        groups: &[
            Group {
                name: "Explore",
                keys: &[
                    k("↑ / ↓ (j/k)", "Move", "Rows, or the sidebar's tools"),
                    k("← / → (h/l)", "Scroll", "Scroll the statistics")
                        .more("Scroll the statistics; the header counts those out of view"),
                    k("Home / End", "First, last", "First or last row"),
                    k("PgUp / PgDn", "Page", "A page"),
                    k("Tab / Shift+Tab", "Focus", "Between the results and the tools"),
                    k("Enter", "Detail", "Q-Q plot and histogram for the column")
                        .more("Open detail view for selected column (shows Q-Q plot and histogram); with the sidebar focused, open a tool"),
                    k("Esc", "Back", "Cancel a run; the tools; then close")
                        .more("Cancel a run in progress; otherwise from the results back to the tools, and from the tools close the analysis view"),
                ],
            },
            Group {
                name: "Sample",
                keys: SAMPLE_KEYS,
            },
        ],
    },
    Screen {
        context: Context::DistributionDetail,
        title: "Analysis: Distribution detail",
        reached: "<kbd>Enter</kbd> on a column in Distribution.",
        groups: &[Group {
            name: "Detail",
            keys: &[
                k("↑ / ↓ (j/k)", "Family", "Compare the values with another family"),
                k("Home / End", "First, last", "The first or last family"),
                k("s", "Scale", "Histogram scale: linear or log"),
                k("Esc", "Back", "Back to the distribution table"),
            ],
        }],
    },
    Screen {
        context: Context::Correlation,
        title: "Analysis: Correlation",
        reached: "Correlation Matrix in the Analysis sidebar.",
        groups: &[
            Group {
                name: "Explore",
                keys: &[
                    k("Tab / Shift+Tab", "Focus", "Between the matrix and the tools"),
                    k("↑ / ↓ (j/k)", "Move", "Matrix rows, or the sidebar's tools"),
                    k("← / → (h/l)", "Column", "Matrix columns"),
                    k("Home / End", "Ends", "The first or last pair")
                        .more("Jump to the first pair (the first row's second column) or the last (the last row's next-to-last column); the matrix opens on the first"),
                    k("PgUp / PgDn", "Page", "A page"),
                    k("Enter", "Detail", "The pair's detail (not on the diagonal)")
                        .more("Open pair detail view (on a cell) or open a tool (sidebar); does nothing on a diagonal cell"),
                    k("m", "Method", "Pearson or Spearman, named in the title")
                        .more("Method: Pearson r or Spearman ρ, named in the title (both come from the one run, so it reads nothing)"),
                    k("Esc", "Back", "Cancel a run; the tools; then close")
                        .more("Cancel a run in progress; otherwise from the matrix back to the tools, and from the tools close the analysis view"),
                ],
            },
            Group {
                name: "Sample",
                keys: SAMPLE_KEYS,
            },
        ],
    },
    Screen {
        context: Context::CorrelationDetail,
        title: "Analysis: Correlation detail",
        reached: "<kbd>Enter</kbd> on a pair in the correlation matrix.",
        groups: &[Group {
            name: "Detail",
            keys: &[
                k("m", "Method", "Pearson or Spearman"),
                k("Esc", "Back", "Back to the correlation matrix")
                    .more("Return to the correlation matrix. Resampling (r) works from the matrix, not from inside this detail"),
            ],
        }],
    },
    Screen {
        context: Context::DataQuality,
        title: "Analysis: Data Quality",
        reached: "Data Quality in the Analysis sidebar.",
        groups: &[
            Group {
                name: "Setup",
                keys: &[
                    k("↑ / ↓, Tab", "Move", "Move between rows"),
                    k("← / →", "Choose", "Change a short list's choice"),
                    k("Space", "Open", "Open the row's form or list")
                        .more("Open the row: the Sample form, a list (type to narrow), Time roles, Intervals, Column intent or Expected"),
                    k("s", "Sample", "The Sample form")
                        .more("The Sample form; its Enter applies to Setup and returns there"),
                    k("p", "Plan", "The access plan: what a run reads"),
                    k("d", "Release", "Release kept rows and the local copy")
                        .more("Release the rows runs kept and a full scan's local copy, named on the Read rule; the next run that would reuse them reads again"),
                    k("Enter", "Run", "Run, from any row")
                        .more("Run, from any row. A full read asks first; the report on screen or in the session cache is shown, not read again"),
                    k("Esc", "Discard", "Discard every staged edit"),
                ],
            },
            Group {
                name: "Setup lists",
                keys: &[
                    k("↑ / ↓", "Move", "Choose the role, pair, column or row")
                        .more("Time roles: choose the role. Intervals: choose the pair. Column intent: choose the column. Expected: Windows, From, Before (Tab too)"),
                    k("← / →", "Choose", "Time roles: its column; Expected: windows")
                        .more("Time roles: choose the role's column. Expected: choose the windows. Intervals: measure the pair or not"),
                    k("Space", "Toggle", "Intervals: measure or not; intent: its form")
                        .more("Intervals: measure the pair or not. Column intent: declare the column's intent in a form"),
                    k("Enter", "Done", "Done"),
                    k("Esc", "Undo", "Put the list back as it was"),
                ],
            },
            Group {
                name: "Report",
                keys: &[
                    k("← / → (h/l)", "Page", "Previous or next page"),
                    k("1 - 5", "Page", "Overview, Columns, Segments, Trends, Intervals")
                        .run("1"),
                    k("↑ / ↓ (j/k)", "Move", "Move, or scroll a tall finding"),
                    k("PgUp / PgDn", "Page", "A page; Home / End the ends")
                        .more("Page; Home/End jump to either end"),
                    k("Enter", "Open", "Open a finding, then its rows")
                        .more("Open a finding, then its rows. On an empty page, open the setting it needs"),
                    k("c / t", "Only", "Overview: one column's or type's findings")
                        .more("Overview: only one column's or one type's findings"),
                    k("o", "Order", "Overview: ranked, by rows, by rate"),
                    k("e", "Setup", "Setup"),
                    k("s", "Sample", "Setup, with the Sample form open"),
                    k("v", "Sample rows", "View the sample's rows; Esc returns"),
                    k("p", "Plan", "The access plan: what a run reads"),
                    k("r", "Resample", "On a sample, run again with a new seed"),
                    k("x", "Export", "Export the report to JSON or Markdown")
                        .more("Export the report to JSON or Markdown; nothing is read"),
                    k("Tab / Shift+Tab", "Focus", "Between the result and the tools"),
                    k("Esc", "Back", "Back one level: all findings, the tools, close")
                        .more("Back one level: all findings again, then the tools, then close"),
                ],
            },
            Group {
                name: "Segments",
                keys: &[
                    k("Enter", "Compare", "The segment's columns beside its comparison")
                        .more("A segment's columns beside the one it is compared with, largest change first"),
                    k("o", "Order", "Largest change first, or back in order"),
                    k("b", "Base", "Compare with the highlighted segment"),
                ],
            },
            Group {
                name: "Trends",
                keys: &[
                    k("Enter", "Bars", "A line's bars, with rate and interval")
                        .more("A line's bars: span, segments, rows sampled of counted, rate, 95% interval, and the bar before. ↑ / ↓ there: the next bar"),
                    k("m", "Measure", "Next measure"),
                    k("w", "Coarser", "Stage a coarser window in Setup")
                        .more("Stage a coarser window in Setup, for segments the sample reached thinly or not at all"),
                    k("g", "Gaps", "The expected windows with no rows")
                        .more("The expected windows with no rows: empty by exact count, not sampled, or out of scope"),
                    k("Esc", "Back", "Back to Trends"),
                ],
            },
            Group {
                name: "Intervals",
                keys: &[
                    k("Enter", "Detail", "An interval's detail; again, its rows")
                        .more("An interval's detail: its ends, the rows with both, missing and unread ends, negative and zero durations, percentiles and breaches. Enter there shows the rows behind the count under the cursor: a sample's from the rows the run kept"),
                    k("Esc", "Back", "Back to the list"),
                ],
            },
        ],
    },
    Screen {
        context: Context::Export,
        title: "Export",
        reached: "<kbd>e</kbd> at the table.",
        groups: &[
            Group {
                name: "Form",
                keys: &[
                    k("Tab / Shift+Tab (↑ / ↓)", "Next", "Next or previous field")
                        .more("Next or previous field, wrapping; the fields follow the format. The dialog opens on Path, and the arrows move from there"),
                    k("← / →", "Change", "Step the format or compression; move the cursor")
                        .more("On Format or Compression: the previous or next value, along the Format row (h/l too). On Header or Source file: toggle. In Path and Delimiter: move the cursor"),
                    k("Space", "Act", "Toggle a checkbox; next format or compression")
                        .more("Toggle a checkbox (Header, Source file); on Format or Compression, the next value, wrapping"),
                    k("Ctrl+P / Ctrl+N", "History", "Earlier or later paths in the path field")
                        .more("In the path field: the paths exported to before, earlier or later (↑ and ↓ move between fields)"),
                    k("Enter", "Export", "Export, from anywhere in the form")
                        .more("Export, from anywhere in the form. On a blank path the form says \"Enter a file path.\" instead of exporting"),
                    k("Esc", "Close", "Close without exporting"),
                ],
            },
            Group {
                name: "File exists",
                keys: &[
                    k("← / → (h/l)", "Pick", "Pick Overwrite or No (Tab too)"),
                    k("Enter", "Confirm", "Confirm the one picked"),
                    k("Esc", "No", "Decline: back to the filled form"),
                ],
            },
        ],
    },
    Screen {
        context: Context::Copy,
        title: "Copy",
        reached: "<kbd>y</kbd> at the table.",
        groups: &[
            Group {
                name: "Form",
                keys: &[
                    k("Tab / Shift+Tab (↑ / ↓)", "Next", "Next or previous row"),
                    k("← / →", "Change", "Step the scope, column or format")
                        .more("The previous or next scope, column or format (h/l too); on Header: toggle"),
                    k("Space", "Act", "Next scope or format; pick a column; toggle")
                        .more("On Scope or Format: the next value, wrapping. On Column: open its picker. On Header: toggle"),
                    k("Enter", "Copy", "Copy, from anywhere in the form")
                        .more("Copy, from anywhere in the form. On the Cell scope with no column picked, Enter re-accents the spec line instead of copying"),
                    k("Esc", "Close", "Close a picker, then the dialog")
                        .more("Close a picker, then the dialog, without copying"),
                ],
            },
            Group {
                name: "Picker",
                keys: &[
                    k("(type)", "Narrow", "Narrow the list").no_run(),
                    k("↑ / ↓", "Move", "Move the cursor (j/k narrow)")
                        .more("Move the cursor (j/k narrow the picker; only ↑/↓ move there)"),
                    k("Enter / Space", "Choose", "Choose"),
                    k("Tab / Shift+Tab", "Next", "Choose and move on"),
                ],
            },
        ],
    },
    Screen {
        context: Context::Views,
        title: "Views",
        reached: "<kbd>v</kbd> at the table.",
        groups: &[
            Group {
                name: "List",
                keys: &[
                    k("↑ / ↓ (j/k)", "Move", "Move in the list"),
                    k("Enter", "Apply", "Apply the selected view"),
                    k("s", "Save", "Save the current state as a view")
                        .more("Save the current state as a view (an untouched table has nothing to save, and s says so)"),
                    k("e", "Edit", "Edit the selected view"),
                    k("d", "Delete", "Delete the selected view, after confirming"),
                    k("i", "Score", "How the view's score was computed")
                        .more("Show how the selected view's score was computed (Esc closes the score view)"),
                    k("Esc", "Close", "Close"),
                ],
            },
            Group {
                name: "Save and edit",
                keys: &[
                    k("Tab / Shift+Tab (↑ / ↓)", "Next", "Next or previous row")
                        .more("Next or previous row. In the description ↑ / ↓ move between its lines, and leave it from the first or last"),
                    k("Enter", "Save", "Save (in the description, Enter types)")
                        .more("Save, from any row. In the description Enter types: Ctrl+J saves from there"),
                    k("Ctrl+J", "Save", "Save from anywhere, the description too")
                        .more("Save from anywhere, the description included; so does Ctrl+Enter, on a terminal that tells it from Enter"),
                    k("PgUp / PgDn", "Lines", "Five lines in the description"),
                    k("Space", "Toggle", "Expand Matching; toggle schema match")
                        .more("Expand or collapse Matching; toggle schema match"),
                    k("Esc", "Back", "Back to the list, discarding edits"),
                ],
            },
            Group {
                name: "Delete",
                keys: &[
                    k("← / → (h/l)", "Pick", "Pick Delete or No (Tab too); it starts on No"),
                    k("Enter", "Confirm", "Confirm the one picked"),
                    k("Esc", "No", "Keep the view"),
                ],
            },
        ],
    },
    Screen {
        context: Context::FormatPicker,
        title: "Format picker",
        reached: "<kbd>b</kbd> at a table read through a format spec.",
        groups: &[Group {
            name: "Pick",
            keys: &[
                k("(type)", "Narrow", "Narrow to the names that contain it").no_run(),
                k("↑ / ↓", "Move", "Move"),
                k("Enter", "Read", "Read the file again with the spec")
                    .more("Read the file again with the spec chosen. The query, filters and sort are cleared"),
                k("Backspace", "Delete", "Delete a character (Ctrl+W a word, Ctrl+U all)"),
                k("Esc", "Close", "Close and keep the format"),
            ],
        }],
    },
    Screen {
        context: Context::Retype,
        title: "Column type",
        reached: "<kbd>Enter</kbd> on the Info panel's Schema tab, or Change type in the cell menu.",
        groups: &[Group {
            name: "Pick",
            keys: &[
                k("(type)", "Narrow", "Narrow the list; a format typed is the format").no_run()
                    .more("Narrow the list to the names that contain it. In the format list, a strftime format typed that no line holds is the format"),
                k("↑ / ↓", "Move", "Move"),
                k("Enter", "Choose", "The type, or its format")
                    .more("The type: the column reads as it at once, a value that does not fit null. A date, time or datetime asks its format next, each line showing what it makes of the column's first value. as read takes the type away"),
                k("Backspace", "Delete", "Delete a character (Ctrl+W a word, Ctrl+U all)"),
                k("Esc", "Back", "Back to the types, or close"),
            ],
        }],
    },
    Screen {
        context: Context::Combine,
        title: "Combine into datetime",
        reached: "Combine into datetime in the cell menu, on a text, date or time column.",
        groups: &[Group {
            name: "Fields",
            keys: &[
                k("Tab / Shift+Tab (↑ / ↓)", "Next", "Next or previous field"),
                k("Space", "Pick", "Pick a column, or step the kind"),
                k("← / →", "Change", "Step the kind: datetime, date or time"),
                k("Enter", "Make", "Make the column")
                    .more("Make the column, before the first column it is made from, as a format spec's derived column is: a date and a time, and a UTC offset, make a datetime in UTC"),
                k("Esc", "Cancel", "Cancel"),
            ],
        }],
    },
    Screen {
        context: Context::TablePicker,
        title: "Table picker",
        reached: "<kbd>T</kbd> at a table of a file of several.",
        groups: &[Group {
            name: "Pick",
            keys: &[
                k("(type)", "Narrow", "Narrow to the names that contain it").no_run(),
                k("↑ / ↓", "Move", "Move"),
                k("Enter", "Open", "Open the table in place of this one")
                    .more("Open the table chosen in place of this one. The query, filters and sort are cleared"),
                k("Backspace", "Delete", "Delete a character (Ctrl+W a word, Ctrl+U all)"),
                k("Esc", "Close", "Close and keep the table"),
            ],
        }],
    },
    Screen {
        context: Context::Sample,
        title: "Sample",
        reached: "<kbd>S</kbd> at the table.",
        groups: &[Group {
            name: "Form",
            keys: &[
                k("Tab / Shift+Tab (↑ / ↓)", "Next", "Next or previous row"),
                k("← / →", "Change", "Step Rows from, Method, Per value of")
                    .more("Step Rows from, Method and Per value of; Method's No sample takes the view's sample away"),
                k("(type)", "Edit", "Type a size (50k, 2m), a seed, rows, values")
                    .more("Type into the focused row: the size (50000, 50k, 2m), the seed, a row range, partition values or file numbers")
                    .no_run(),
                k("Enter", "Draw", "Draw the sample; again past a memory warning")
                    .more("Draw the sample: the table shows its rows as they arrive, and the query, filters and sort run over them. When the estimate is more than the memory available now (or analysis.sample_memory_limit), the form says so; Enter again draws anyway"),
                k("Esc", "Cancel", "Close; the view's sample stays as it was"),
            ],
        }],
    },
    Screen {
        context: Context::Hex,
        title: "Hex view",
        reached: "`datui --hex FILE`, <kbd>Ctrl</kbd>+<kbd>X</kbd> on the home screen, or <kbd>x</kbd> in the Info panel.",
        groups: &[
            Group {
                name: "Explore",
                keys: &[
                    k("← / → (h/l)", "Byte", "A byte"),
                    k("↑ / ↓ (j/k)", "Row", "A row"),
                    k("w / b", "Group", "The next group of four, or back one"),
                    k("0 / $", "Row ends", "The start or end of the row"),
                    k("g / G", "File ends", "Start or end of the file (Home / End too)")
                        .more("The start or end of the file (Home and End too)"),
                    k("PgUp / PgDn", "Page", "A page (Ctrl+B / F; Ctrl+U / D half)")
                        .more("A page (Ctrl+B/F too; Ctrl+U/D half a page)"),
                    k(":", "Go to", "Go to an offset: 4096, 0x1000, +16, e-8")
                        .more("Go to an offset: 4096 or 0x1000; +16 or -16 from the cursor; e-8 for the eighth byte from the end"),
                ],
            },
            Group {
                name: "Find",
                keys: &[
                    k("f", "Find", "Find text or bytes (de ad, 0x1acf, ?? any)")
                        .more("Find bytes. Text is found as its UTF-8 bytes (Ctrl+U in the prompt: as UTF-16 little-endian). 0x1acffc1d, or two or more hex pairs (de ad be ef), is a byte pattern, where ?? matches any byte. Text in double quotes is text, even when it looks like hex. A match may span rows"),
                    k("n / N", "Next, previous", "Next or previous match, round the end")
                        .more("The next or previous match, round the end of the file"),
                    k("R", "Stride", "Bytes per row from the matches' spacing")
                        .more("When the matches after the one found are all the same distance apart, make that the bytes per row"),
                    k("Esc", "Stop", "Stop a find that is reading"),
                ],
            },
            Group {
                name: "Display",
                keys: &[
                    k("r", "Row size", "Bytes per row; empty: as many as fit")
                        .more("Bytes per row, so that records line up; empty goes back to as many as fit. --hex-width N sets it on the command line"),
                    k("#", "Offsets", "Offsets in decimal or hex"),
                    k("i / Enter", "Inspector", "Show or hide the byte inspector")
                        .more("Show or hide the byte inspector. Beside the bytes when there is room for it and 16 bytes a row, over them when there is not"),
                    k("v", "Mark", "Mark a range from the cursor; again to unmark")
                        .more("Mark from the cursor; move to mark a range, and the status line counts it. v again, or Esc, unmarks"),
                ],
            },
            Group {
                name: "Go",
                keys: &[
                    k("B", "Format spec", "Read the file with a format spec instead"),
                    k("Esc", "Back", "Back to the Info panel or home")
                        .more("Back to the table, when opened from the Info panel; back home, when opened from there"),
                    k("q", "Back", "Home, when opened from there; else quit"),
                ],
            },
        ],
    },
];

/// The screen for `context`.
pub fn screen(context: Context) -> &'static Screen {
    SCREENS
        .iter()
        .find(|s| s.context == context)
        .expect("every context has a screen")
}

/// The entry for `keys` on `context`'s screen, or in `group` of it when named: what
/// the footer's hints read their labels from.
pub fn lookup(context: Context, group: Option<&str>, keys: &str) -> Option<&'static Key> {
    screen(context)
        .groups
        .iter()
        .filter(|g| group.is_none_or(|name| g.name == name))
        .flat_map(|g| g.keys.iter())
        .find(|k| k.keys == keys)
}

/// Every key entry with its screen and group, in reference order; [`GLOBAL`] first.
pub fn entries() -> impl Iterator<Item = (Option<&'static Screen>, &'static Group, &'static Key)> {
    GLOBAL
        .keys
        .iter()
        .map(|key| (None, &GLOBAL, key))
        .chain(SCREENS.iter().flat_map(|screen| {
            screen
                .groups
                .iter()
                .flat_map(move |group| group.keys.iter().map(move |key| (Some(screen), group, key)))
        }))
}

/// Escape text for a markdown table cell.
fn cell(text: &str) -> String {
    text.replace('|', "\\|")
        .replace('<', "&lt;")
        .replace('>', "&gt;")
}

/// A key label as markdown: code, so `[` and `*` read as themselves.
fn key_cell(label: &str) -> String {
    if label.contains('`') {
        format!("`` {} ``", label.replace('|', "\\|"))
    } else {
        format!("`{}`", label.replace('|', "\\|"))
    }
}

fn markdown_table(out: &mut String, keys: &[Key]) {
    out.push_str("\n| Key | Action |\n|---|---|\n");
    for key in keys {
        out.push_str(&format!(
            "| {} | {} |\n",
            key_cell(key.keys),
            cell(key.long())
        ));
    }
}

/// The keyboard reference: the keys every screen takes, then each screen's.
pub fn render_markdown() -> String {
    let mut out = String::new();
    out.push_str("\n## Every screen\n\nThese keys work on every screen.\n");
    markdown_table(&mut out, GLOBAL.keys);
    out.push_str("\n## Help\n\n<kbd>?</kbd> or <kbd>F1</kbd>.\n");
    markdown_table(&mut out, HELP.keys);
    for screen in SCREENS {
        out.push_str(&format!("\n## {}\n\n{}\n", screen.title, screen.reached));
        for group in screen.groups {
            out.push_str(&format!("\n### {} · {}\n", screen.title, group.name));
            markdown_table(&mut out, group.keys);
        }
    }
    out
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn first_keys_are_read() {
        for (keys, first) in [
            ("↑ / ↓ (j/k)", "↑"),
            ("Ctrl+D / Ctrl+U", "Ctrl+D"),
            ("PgUp/PgDn", "PgUp"),
            ("/", "/"),
            ("+ / - (= / _)", "+"),
            ("e, w, y, o", "e"),
            ("Enter (d / D)", "Enter"),
            ("↑ / ↓, Tab", "↑"),
            ("Click a key", "Click"),
        ] {
            assert_eq!(first_key(keys), first, "{keys}");
        }
    }

    #[test]
    fn chords_are_read() {
        let c = chord("Ctrl+O").unwrap();
        assert!(c.ctrl && !c.shift && c.code == Code::Char('o'));
        assert_eq!(chord("G").unwrap().code, Code::Char('G'));
        assert!(chord("G").unwrap().shift);
        assert_eq!(chord("Shift+Tab").unwrap().code, Code::BackTab);
        assert_eq!(chord("F1").unwrap().code, Code::F(1));
        assert_eq!(chord("↓").unwrap().code, Code::Down);
        assert_eq!(chord("Space").unwrap().code, Code::Char(' '));
        assert_eq!(chord("+").unwrap().code, Code::Char('+'));
        assert!(chord("Click").is_none());
        assert!(chord("(type)").is_none());
        assert!(chord("1-9").is_none());
        let codes: Vec<Code> = chords("↑ / ↓ (j/k)").iter().map(|c| c.code).collect();
        assert_eq!(
            codes,
            [Code::Up, Code::Down, Code::Char('j'), Code::Char('k')]
        );
        assert_eq!(chords("PgUp/PgDn").len(), 2);
        assert_eq!(chords("/")[0].code, Code::Char('/'));
        assert!(chords("(type)").is_empty());
    }

    /// Every entry's Enter presses a key, unless it says it presses none; every line
    /// is one line, short enough for half the help; every label is three words at most.
    #[test]
    fn every_entry_is_whole() {
        let mut bad = Vec::new();
        for (screen, group, key) in entries() {
            let at = format!(
                "{} · {} · {}",
                screen.map_or("Global", |s| s.title),
                group.name,
                key.keys
            );
            if key.run != Run::Never && key.action().is_none() {
                bad.push(format!("{at}: Enter presses nothing; .run() or .no_run()"));
            }
            if key.line.contains('\n') || key.line.chars().count() > 52 {
                bad.push(format!("{at}: line longer than 52: {}", key.line));
            }
            if key.label.is_empty() || key.label.split(' ').count() > 3 {
                bad.push(format!("{at}: label {:?}", key.label));
            }
            if key.line.ends_with('.') || key.more.is_some_and(|m| m.ends_with('.')) {
                bad.push(format!("{at}: ends with a period"));
            }
            if key.more == Some(key.line) {
                bad.push(format!("{at}: more repeats the line"));
            }
        }
        assert!(bad.is_empty(), "{}", bad.join("\n"));
    }

    #[test]
    fn every_context_has_one_screen() {
        use std::collections::HashSet;
        let contexts: HashSet<_> = SCREENS.iter().map(|s| s.context).collect();
        assert_eq!(contexts.len(), SCREENS.len(), "a context is listed twice");
        for screen in SCREENS {
            assert!(!screen.groups.is_empty(), "{} has no keys", screen.title);
            let mut names = HashSet::new();
            for group in screen.groups {
                assert!(
                    names.insert(group.name),
                    "{}: {} twice",
                    screen.title,
                    group.name
                );
                assert!(!group.keys.is_empty());
            }
        }
    }
}