// The semantic elements every docs/typ topic uses, and the one place they
// are defined. Content files call them ("this is a key", "this is a
// builtin"); how each looks is decided here, per output: paged outputs
// (the A4 cheatsheet, later the book) draw them, HTML export gives them
// elements and classes for a stylesheet. Page geometry and fonts belong to
// the output wrappers beside this file.

/// The `atelier` theme (src/themes/atelier.zig): pardes's acme homage,
/// butter paper and blue-green tags.
#let palette = (
  paper: rgb("#fffdeb"),
  ink: rgb("#293f35"),
  tag-bg: rgb("#e4f0ed"),
  tag-fg: rgb("#3d6055"),
  tag-name: rgb("#6e4774"),
  grip: rgb("#36826b"),
  col-grip: rgb("#955815"),
  str: rgb("#34743d"),
  num: rgb("#9a5810"),
  rule: rgb("#95baa2"),
  mouse: rgb("#8a3a00"),
)
#let mono = "DejaVu Sans Mono"

/// Topic ids for #doc: each names a chapter (an id in `chapters`) and,
/// optionally, the label of a section in it. Old ids stay so older calls
/// keep working.
#let topics = (
  guide: ("guide", none),
  setup: ("setup", none),
  cheatsheet: ("cheatsheet", none),
  scripting: ("scripting", none),
  reference: ("reference", none),
  themes: ("themes", none),
  building: ("building", none),
  builtins: ("builtins", none),
  tags: ("guide", none),
  fs: ("reference", none),
  config: ("guide", "config"),
  keys: ("guide", "keys"),
  detached: ("guide", "sessions"),
)

/// Set by a wrapper that holds every chapter (the book, the HTML): #doc
/// then links to the chapter or section. Alone (the A4 sheet) it names it.
#let doc-links = state("doc-links", false)

/// The book's and the HTML's reading order. `file` is the content file
/// in docs/typ, or none while the topic is not written yet (the outputs
/// then show a placeholder). Wrappers include each with heading offset 1,
/// so a file's `=` headings sit under its chapter title, labelled
/// `ch-<id>`.
#let chapters = (
  (id: "guide", title: "Guide", file: "guide.typ"),
  (id: "setup", title: "Setting up your environment", file: "setup.typ"),
  (id: "cheatsheet", title: "Cheatsheet", file: "cheatsheet.typ"),
  (id: "scripting", title: "Scripting", file: "scripting.typ"),
  (id: "reference", title: "Reference", file: "reference.typ"),
  (id: "builtins", title: "Builtins", file: "builtins.typ"),
  (id: "themes", title: "Themes", file: "themes.typ"),
  (id: "building", title: "Building, for contributors", file: "building.typ"),
)

/// The one-line pitch: the A4 sheet's header and the book's title page.
#let tagline = "acme's tags and three buttons, helix's keys, terminals as panes, the editor as a virtual filesystem over 9P"

/// The tutor, shown as it is in the editor (`Tutor`), from the repo root.
#let tutor-path = "/src/tutor.txt"

/// How much room tables and shell lines get: "roomy" (the book, the HTML)
/// or "tight" (the A4 sheet sets it).
#let density = state("density", "roomy")

#let html-out() = target() == "html"
#let span(class, body) = html.elem("span", attrs: (class: class), body)
#let m(s, fill: palette.ink) = text(font: mono, size: 0.92em, fill: fill, s)

/// A key: one press (`x`, `Ctrl-w`, `Shift-Esc`), or a sequence pressed one
/// after another, written space-separated (`g g`, `SPC f c`). Either is ONE
/// pill: a combination's parts joined by a muted +, a sequence's steps by a
/// muted › (`Ctrl-w h` reads Ctrl + w › h).
#let key(k) = context if html-out() {
  let sep(c, cls) = html.elem("span", attrs: (class: cls, "aria-hidden": "true"), c)
  let press(t) = (if t.len() > 1 and t.contains("-") { t.split("-") } else { (t,) }).join(sep("+", "plus"))
  html.elem("kbd", attrs: (class: "key"), k.split(" ").map(press).join(sep("›", "then")))
} else {
  let muted(c) = text(fill: palette.grip.transparentize(25%), size: 0.85em, c)
  let press(t) = (if t.len() > 1 and t.contains("-") { t.split("-") } else { (t,) }).join(muted[+])
  box(
    fill: palette.grip.transparentize(84%), radius: 2pt,
    inset: (x: 1.4pt, y: 0pt), outset: (y: 1.5pt),
    text(font: mono, size: 0.92em, fill: palette.ink,
      k.split(" ").map(press).join(muted[#h(1pt)›#h(1pt)])),
  )
}

/// Alternatives: separate keys listed together, each its own command.
#let keys(..ks) = context ks.pos().map(key).join(if html-out() [ ] else { h(0.25em) })

#let button-names = ("B1": "left button", "B2": "wheel", "B3": "right button")
#let click-names = ("B1": "left", "B2": "middle", "B3": "right")
/// Text that is read and copied but not shown, beside a drawn glyph.
#let hidden(t) = html.elem("span", attrs: (class: "vh"), t)

/// A mouse, about cap height: left button, wheel, right button. The parts
/// in `pressed` ("B1", "B2", "B3") are filled.
#let mouse(pressed) = {
  let (w, h, top) = (0.84em, 1.2em, 0.56em)
  let ink = palette.mouse
  let s = 0.7pt + ink
  let on(b) = if b in pressed { ink } else { none }
  box(width: w, height: h, baseline: 0.24em, {
    place(rect(width: w / 2, height: top, radius: (top-left: w / 2), fill: on("B1"), stroke: s))
    place(dx: w / 2, rect(width: w / 2, height: top, radius: (top-right: w / 2), fill: on("B3"), stroke: s))
    place(dy: top, rect(width: w, height: h - top, radius: (bottom: w / 2), stroke: s))
    // the wheel: a narrow tall slot over the buttons' seam, on a paper
    // halo so a filled wheel stands apart from the button outlines
    let (ww, wh, halo) = (0.26em, 0.44em, 0.07em)
    let (wx, wy) = ((w - ww) / 2, 0.06em)
    place(dx: wx - halo, dy: wy - halo / 2, rect(
      width: ww + 2 * halo, height: wh + halo, radius: ww, fill: palette.paper))
    place(dx: wx, dy: wy, rect(
      width: ww, height: wh, radius: ww / 2, stroke: 0.5pt + ink,
      fill: if "B2" in pressed { ink } else { palette.paper },
    ))
  })
}

/// The same mouse as inline SVG for HTML. Each part is classed `on`
/// (pressed) or `off`, and the stylesheet colours them: the pressed part
/// filled in the accent, the rest outlined and muted.
#let mouse-svg(pressed) = {
  let cls(b) = if b in pressed { "on" } else { "off" }
  let part(d, b) = html.elem("path", attrs: (class: cls(b), d: d))
  html.elem("svg", attrs: (class: "mouse", viewBox: "-6 -6 96 132", "aria-hidden": "true"), {
    // taller buttons and a slimmer wheel than on paper, so a pressed
    // button shows as a solid block at body size
    part("M0 64H84V78A42 42 0 0 1 0 78Z", none)
    part("M0 64V42A42 42 0 0 1 42 0V64Z", "B1")
    part("M42 0A42 42 0 0 1 84 42V64H42Z", "B3")
    // a pressed wheel is drawn wider, so it reads as pressed, not as a seam
    let (hx, hw, wx, ww) = if "B2" in pressed { ("27", "30", "31", "22") } else { ("31", "22", "35", "14") }
    html.elem("rect", attrs: (class: "halo", x: hx, y: "4", width: hw, height: "48", rx: "13"))
    html.elem("rect", attrs: (class: "wheel " + cls("B2"), x: wx, y: "8", width: ww, height: "40", rx: "9"))
  })
}

/// A mouse button; `shift: true` for the button with Shift held.
#let btn(b, shift: false) = context if html-out() {
  let label = (if shift { "shift " } else { "" }) + button-names.at(b)
  html.elem("span", attrs: (class: "btn", title: label), {
    if shift { html.elem("span", attrs: (class: "shift", "aria-hidden": "true"), "⇧") }
    mouse-svg((b,))
    hidden((if shift { "Shift-" } else { "" }) + click-names.at(b) + "-click")
  })
} else {
  if shift { text(size: 0.8em, fill: palette.col-grip)[⇧] }
  mouse((b,))
}

/// A chord: the first button held, each next one clicked while it is.
/// Drawn as the held button, then for each click the held one and that one
/// down, with arrows between.
#let chord(..bs) = context if html-out() {
  let label = bs.pos().map(b => button-names.at(b)).join(" then ")
  let (held, ..clicks) = bs.pos()
  let arrow = html.elem("span", attrs: (class: "then", "aria-hidden": "true"), "›")
  let said = "hold " + click-names.at(held) + ", click " + clicks.map(c => click-names.at(c)).join(", then ")
  html.elem("span", attrs: (class: "chord", title: label), {
    ((mouse-svg((held,)),) + clicks.map(c => mouse-svg((held, c)))).join(arrow)
    hidden(said)
  })
} else {
  let (held, ..clicks) = bs.pos()
  let arrow = text(size: 0.75em, fill: palette.col-grip)[#h(0.5pt)›#h(0.5pt)]
  ((mouse((held,)),) + clicks.map(c => mouse((held, c)))).join(arrow)
}

/// A tag word or builtin, drawn as a thing to click: the tag's ground and
/// ink in the tag's monospace, over a rule. Look and Exec take acme's look
/// and exec sweep colours (green and red, src/themes/acme.zig) for the
/// rule; every other word the tag's box colour. In HTML a <code
/// class="word">, so a text browser still shows the plain word.
#let word-accent = (Look: rgb("#006600"), Exec: rgb("#aa0000"))

/// Every builtin of either build, written by `zig build builtins-json`
/// from the registry and the Help rows (src/builtins_json.zig), a file per
/// build: name, leader, also (Help's other shortcuts), arg, scope, setting,
/// choices, doc. Merged here, each with `platforms`: "both", "tty" (the
/// terminal only) or "gui" (the window only).
#let builtin-data = {
  let tty = json("builtins-tty.json")
  let gui = json("builtins-gui.json")
  let in-tty = tty.map(b => b.name)
  let in-gui = gui.map(b => b.name)
  let all = (tty + gui.filter(b => b.name not in in-tty)).sorted(key: b => b.name)
  all.map(b => {
    b.insert("platforms", if b.name in in-tty and b.name in in-gui { "both" } else if b.name in in-tty { "tty" } else { "gui" })
    b
  })
}
#let builtin-names = builtin-data.map(b => b.name)

#let word-chip(w) = context if html-out() {
  let base = w.split("+").first()
  let kind = if base == "Look" { " look" } else if base == "Exec" { " exec" } else { "" }
  html.elem("code", attrs: (class: "word" + kind), w)
} else {
  let rule = word-accent.at(w.split("+").first(), default: palette.grip)
  box(
    fill: palette.tag-bg, inset: (x: 1.4pt, y: 0pt), outset: (y: 1.4pt),
    stroke: (bottom: 0.6pt + rule),
    m(w, fill: palette.tag-fg),
  )
}

/// A builtin's word links to its glossary entry wherever the glossary is
/// part of the same output (the book, the site); elsewhere it is the chip.
#let word(w) = context {
  let base = w.split("+").first()
  let target = label("builtin-" + base)
  if doc-links.get() and base in builtin-names and query(target).len() > 0 {
    link(target, word-chip(w))
  } else { word-chip(w) }
}

/// A whole tagline: its grip, the path, then its words.
#let tag(words, path: none) = context if html-out() {
  html.elem("div", attrs: (class: "tag"), {
    html.elem("span", attrs: (class: "grip", "aria-hidden": "true"))[]
    if path != none { span("path", path); [ ] }
    raw(words)
  })
} else {
  block(width: 100%, fill: palette.tag-bg, inset: (x: 2pt, y: 2.4pt), spacing: 0.5em, {
    box(fill: palette.grip, width: 0.55em, height: 0.75em, baseline: 0.1em)
    h(3pt)
    if path != none { m(path, fill: palette.tag-name); h(0.6em) }
    m(words, fill: palette.tag-fg)
  })
}

/// A look address.
#let addr(a) = context if html-out() { span("addr", raw(a)) } else { m(a, fill: palette.tag-name) }

/// A 9P path.
#let file(p) = context if html-out() { span("file", raw(p)) } else { m(p, fill: palette.str) }

/// A shell line.
#let cmd(c) = context if html-out() { html.elem("div", attrs: (class: "cmd"), raw(c, block: true, lang: "sh")) } else {
  let tight = density.get() == "tight"
  block(
    width: 100%, spacing: if tight { 0.4em } else { 0.9em },
    inset: if tight { (left: 3pt, y: 1.2pt) } else { (left: 6pt, y: 3pt) },
    stroke: (left: (if tight { 1pt } else { 1.5pt }) + palette.rule),
    fill: if tight { none } else { palette.tag-bg.transparentize(50%) },
    text(font: mono, size: 0.85em, fill: palette.ink, c),
  )
}

/// Where the full story is: a topic id from `topics`, and a section label
/// in it. A link where the wrapper holds the chapters, else its name.
#let doc(id, section: none) = {
  let (chapter, default) = topics.at(id)
  let section = if section != none { section } else { default }
  let title = chapters.find(c => c.id == chapter).title
  let to = label(if section != none { section } else { "ch-" + chapter })
  let named = title + if section != none { ": " + section.replace("-", " ") } else { "" }
  context {
    if doc-links.get() {
      let found = query(to)
      let shown = if found.len() > 0 and found.first().func() == heading {
        if section != none [#title: #found.first().body] else [#title]
      } else [#named]
      link(to, text(fill: palette.num)[→ #shown])
    } else {
      text(fill: palette.num)[→ #named]
    }
  }
}

/// Pairs: a thing and what it means, as a two-column table, key column
/// first, rows on alternating tints. `split: 2` sets the rows as that many
/// tables side by side (on paper; HTML gets one table).
#let pairs(split: 1, ..cells) = {
  let rows = cells.pos().chunks(2)
  context {
    let tight = density.get() == "tight"
    let one(rows) = table(
      columns: (auto, 1fr), stroke: none,
      inset: if tight { (x: 2pt, y: 1.6pt) } else { (x: 7pt, y: 4pt) },
      fill: (_, y) => if calc.even(y) { palette.tag-bg.transparentize(35%) },
      ..rows.flatten(),
    )
    if html-out() or split == 1 { one(rows) } else {
      let n = calc.ceil(rows.len() / split)
      grid(columns: (1fr,) * split, column-gutter: if tight { 2pt } else { 10pt }, ..rows.chunks(n).map(one))
    }
  }
}

/// Where pardes lives and under what licence: install.typ, the site's
/// landing and its footer all read it. Every mirror holds the same tree;
/// the first is the one the install line clones. A new mirror is one line.
#let project = (
  mirrors: (
    (name: "sourcehut", web: "https://git.sr.ht/~gbrls/pardes", clone: "https://git.sr.ht/~gbrls/pardes"),
    (name: "git.0x4200.cafe", web: "https://git.0x4200.cafe/pardes", clone: "https://git.0x4200.cafe/pardes.git"),
  ),
  license: "ISC",
  changes: "https://git.sr.ht/~gbrls/pardes/tree/main/item/src/CHANGELOG.md",
  // built binaries to download: the version they are, where the
  // checksums are, and a file per program (install.typ shows them)
  download: (
    version: "0.23",
    sums: "https://pub-66384ba880784f119ce95123b92fa5c6.r2.dev/SHA256SUMS",
    files: (
      (program: "pardes", what: "the terminal build, static, any x86_64 Linux",
        url: "https://pub-66384ba880784f119ce95123b92fa5c6.r2.dev/pardes-x86_64-linux-static", bytes: 62034424,
        sha256: "9db75765a8ad2fc881164b98ff69f0d34ded582304428c28aee7f87ccb211061"),
      (program: "pardes-gui", what: "the window, x86_64 Linux with glibc 2.29 or later; it loads Wayland or X11 and GL or Vulkan from the system",
        url: "https://pub-66384ba880784f119ce95123b92fa5c6.r2.dev/pardes-gui-x86_64-linux", bytes: 66620552,
        sha256: "d788213d14e69ee32348cee9b707b046c71c208c6436d84988e76aaf117095da"),
    ),
  ),
)

/// A glossary: like #pairs, under its own heading. On paper the heading
/// and the table; in HTML a <details> that starts closed, its summary the
/// heading and the count, so a reader who knows the words skips them.
#let glossary(title, lbl, ..cells) = context if html-out() {
  // a real definition list, so a text browser reads term, then meaning
  html.elem("details", attrs: (class: "glossary"), {
    html.elem("summary", [#heading(title) #lbl])
    html.elem("dl", for (term, meaning) in cells.pos().chunks(2) {
      html.elem("dt", term)
      html.elem("dd", meaning)
    })
  })
} else {
  [#heading(title) #lbl]
  pairs(..cells)
}

/// Every theme as a picture, on the site's Themes page; nothing on paper,
/// where forty-odd screenshots would only add weight. Reads
/// docs/site/media/themes/themes.toml: `ready` (absent means true) and a
/// [[theme]] per theme, in NextColor's order, with `name`, `file` (under
/// media/themes/) and `kind` ("light" or "dark").
#let theme-gallery() = context if html-out() {
  let g = toml("../site/media/themes/themes.toml")
  let ready = g.at("ready", default: true)
  heading[Every theme]
  html.elem("div", attrs: (class: "gallery"), for t in g.theme {
    let src = "media/themes/" + t.file
    html.elem("figure", attrs: (class: "shot " + t.kind), {
      if ready {
        html.elem("a", attrs: (href: src), html.elem("img", attrs: (src: src, alt: t.name + " (" + t.kind + ")", loading: "lazy")))
      } else {
        html.elem("div", attrs: (class: "pending"), "screenshot to come")
      }
      html.elem("figcaption", raw(t.name))
    })
  })
}

/// The newcomer's words, first in the glossary; every other builtin goes
/// under its group below. Each must be in builtins.json.
#let everyday = ("Look", "Exec", "Save", "Undo", "Redo", "New", "Newcol", "Del", "Delcol",
  "Tty", "Kill", "Find", "Grep", "Recent", "Dump", "Restore", "Exit", "Help", "Tutor", "Themes", "Config")
/// Debugging and developer words, last whatever their leader path.
#let internals = ("Debug", "EffectCode", "Lspwhy", "Messages", "DumpConfig", "DumpThemes")

/// The glossary's groups, in order: by the leader path's first key, the
/// way Help groups them, then settings, the words with no path, internals.
#let builtin-groups = (
  (title: "Files", keys: ("f",)),
  (title: "Panes and columns", keys: ("c", "d")),
  (title: "Moving and jumps", keys: ("w", "j")),
  (title: "Terminals", keys: ("n",)),
  (title: "Language server", keys: ("l",)),
  (title: "Sessions", keys: ("s", "q")),
  (title: "Help", keys: ("h", "?")),
  (title: "Clipboard", keys: ("y", "Y", "p", "P", "R")),
  (title: "Toggles", keys: ("t",)),
  (title: "Settings and themes", keys: "setting"),
  (title: "Animations", keys: ("a",)),
  (title: "Other words", keys: "none"),
)

#let group-of(b) = {
  if b.name in internals { return "internals" }
  if b.setting { return "setting" }
  if b.leader == none { return "none" }
  b.leader.split(" ").at(1)
}

/// Help spells a shortcut its own way (C-w left, right-click, topbar);
/// this draws it as the docs do.
#let shortcut(s) = {
  if s == "topbar" { return [in the workspace tag] }
  if s == "middle-click" { return btn("B2") }
  if s == "right-click" { return btn("B3") }
  if s == "left-click" { return btn("B1") }
  let names = (enter: "Enter", tab: "Tab", escape: "Esc", left: "Left", right: "Right", up: "Up", down: "Down",
    home: "Home", end: "End", backspace: "Backspace", delete: "Delete", page_up: "PgUp", page_down: "PgDn")
  key(s.split(" ").map(t => {
    let mods = ""
    while t.len() > 2 and t.at(1) == "-" and t.at(0) in ("C", "A", "S") {
      mods += (C: "Ctrl-", A: "Alt-", S: "Shift-").at(t.at(0))
      t = t.slice(2)
    }
    mods + names.at(t, default: t)
  }).join(" "))
}

/// A doc comment's text, its `code` spans set as code.
#let prose(t) = t.split("`").enumerate().map(((i, part)) => if calc.odd(i) { raw(part) } else { part }).join()

#let builtin-entry(b) = [
  #heading(depth: 2, raw(b.name)) #label("builtin-" + b.name)
  #let keys = (if b.leader != none { (key(b.leader),) } else { () }) + b.also.map(shortcut)
  #if b.platforms != "both" [#emph(if b.platforms == "gui" [window only] else [terminal only]) · ]
  #if keys.len() > 0 [#keys.join([, ]) · ]
  #if b.choices != none [#raw(b.choices.replace(", ", "|")) · ] else if b.arg [takes an argument · ]
  #prose(b.doc)
]

/// The glossary: everyday words first, then the groups, then internals,
/// each alphabetical. A level-1 heading per group in the content file.
#let builtin-glossary() = {
  let by-name = (:)
  for b in builtin-data { by-name.insert(b.name, b) }
  [= Everyday <builtins-everyday>]
  for n in everyday.sorted() { builtin-entry(by-name.at(n)) }
  let rest = builtin-data.filter(b => b.name not in everyday)
  for g in builtin-groups {
    let members = rest.filter(b => {
      let k = group-of(b)
      if type(g.keys) == str { k == g.keys } else { k in g.keys }
    })
    if members.len() > 0 {
      heading(depth: 1, g.title)
      for b in members { builtin-entry(b) }
    }
  }
  let inner = rest.filter(b => group-of(b) == "internals")
  if inner.len() > 0 {
    [= Debugging and internals]
    for b in inner { builtin-entry(b) }
  }
  // a builtin no group took is a bug in builtin-groups, not a silent drop
  let placed = everyday + rest.filter(b => {
    let k = group-of(b)
    k == "internals" or builtin-groups.any(g => if type(g.keys) == str { k == g.keys } else { k in g.keys })
  }).map(b => b.name)
  for b in builtin-data { assert(b.name in placed, message: "builtin " + b.name + " is in no glossary group") }
  // last, every word at once, A to Z, each a link to its entry
  [= All builtins, A–Z <builtins-a-z>]
  context if html-out() {
    html.elem("p", attrs: (class: "all-words"),
      builtin-data.map(b => link(label("builtin-" + b.name), word-chip(b.name))).join(" "))
  } else {
    par(builtin-data.map(b => link(label("builtin-" + b.name), word-chip(b.name))).join(h(0.4em)))
  }
}

/// A directory tree drawn as `tree` draws one. `spec` is a raw block, a
/// line per file: two spaces of indent per level, the name (a directory
/// ends in `/`), two or more spaces, a one-line description, and an
/// optional `@label` naming the section that documents it, which becomes
/// a link wherever that section is in the same output. A description may
/// call #word, #key, #keys or #btn. src/config.zig's
/// test reads the same block in reference.typ against the served tree.
#let fstree(spec, root: "/") = {
  // a description is text, unless it calls #word, #key or #btn
  let said(d) = if d.contains("#") { eval(d, mode: "markup", scope: (word: word, key: key, keys: keys, btn: btn)) } else { d }
  let rows = spec.text.split("\n").filter(l => l.trim() != "").map(l => {
    let depth = calc.quo(l.len() - l.trim(at: start).len(), 2)
    let m = l.trim().match(regex("^(\S+)(?:\s{2,}(.*?))?(?:\s+@([a-z0-9-]+))?$"))
    (depth: depth, name: m.captures.at(0), desc: m.captures.at(1), anchor: m.captures.at(2))
  })
  // the connector for each row: is each ancestor, and the row itself, the
  // last among its siblings?
  let last(i) = {
    let d = rows.at(i).depth
    for j in range(i + 1, rows.len()) {
      if rows.at(j).depth < d { return true }
      if rows.at(j).depth == d { return false }
    }
    true
  }
  let lasts = range(rows.len()).map(last)
  let prefix(i) = {
    let d = rows.at(i).depth
    let out = ""
    // for each ancestor depth, the nearest row above at that depth
    for k in range(d) {
      let a = range(i).rev().find(j => rows.at(j).depth == k)
      out += if lasts.at(a) { "    " } else { "│   " }
    }
    out + if lasts.at(i) { "└── " } else { "├── " }
  }
  let named(r) = context {
    let t = if r.anchor != none { label(r.anchor) } else { none }
    if t != none and query(t).len() > 0 { link(t, r.name) } else { r.name }
  }
  let width = calc.max(..range(rows.len()).map(i => prefix(i).len() + rows.at(i).name.len()))
  context if html-out() {
    let nl = html.elem("span", attrs: (class: "nl"), "\n")
    html.elem("pre", attrs: (class: "fstree", style: "--name:" + str(width + 2) + "ch"), {
      html.elem("span", attrs: (class: "row root"), [#html.elem("span", attrs: (class: "name dir"), root)#nl])
      for (i, r) in rows.enumerate() {
        let pad = " " * (width - prefix(i).clusters().len() - r.name.len() + 2)
        html.elem("span", attrs: (class: "row"), {
          html.elem("span", attrs: (class: if r.name.ends-with("/") { "name dir" } else { "name" }),
            [#html.elem("span", attrs: (class: "branch"), prefix(i))#named(r)#pad])
          if r.desc != none {
            html.elem("span", attrs: (class: "desc", style: "--cols:" + str(prefix(i).clusters().len())), said(r.desc))
          }
          nl
        })
      }
    })
  } else {
    set text(font: mono, size: 0.82em)
    block(width: 100%, grid(columns: (auto, 1fr), column-gutter: 1.2em, row-gutter: 0pt, inset: (y: 0.12em),
      text(weight: "bold", fill: palette.grip, root), [],
      ..rows.enumerate().map(((i, r)) => (
        [#text(fill: palette.rule, prefix(i))#text(fill: if r.name.ends-with("/") { palette.grip } else { palette.ink },
          weight: if r.name.ends-with("/") { "bold" } else { "regular" }, named(r))],
        text(font: "Libertinus Serif", size: 1.2em, fill: palette.tag-fg, if r.desc == none { [] } else { said(r.desc) }),
      )).flatten()))
  }
}

/// A screenshot with numbered pins on it and their labels as text beside
/// it, so the labels read, search and translate as text. `src` is from
/// the repository root (the site serves it from the same path under
/// docs/site/); `size` is its pixel (width, height); each pin is (label,
/// x, y) in pixels of that image.
#let annotated(src, size, alt: "", ..pins) = {
  let (w, h) = size
  let pins = pins.pos()
  context if html-out() {
    let web = src.trim("/docs/site/", at: start)
    html.elem("figure", attrs: (class: "annotated"), {
      html.elem("div", attrs: (class: "frame"), {
        html.elem("img", attrs: (src: web, alt: alt, width: str(w), height: str(h)))
        for (i, (label, x, y)) in pins.enumerate() {
          html.elem("span", attrs: (class: "pin", "aria-hidden": "true",
            // repr, not str: str writes a negative with U+2212, which CSS rejects
            style: "left:" + repr(calc.round(100 * x / w, digits: 2)) + "%;top:" + repr(calc.round(100 * y / h, digits: 2)) + "%"), str(i + 1))
        }
      })
      html.elem("ol", attrs: (class: "pins"), for (label, x, y) in pins { html.elem("li", label) })
    })
  } else {
    let width = 11cm
    let k = width / w
    let pin(n) = box(width: 1.25em, height: 1.25em, radius: 50%, fill: palette.mouse,
      align(center + horizon, text(size: 0.75em, weight: "bold", fill: white, str(n))))
    block(breakable: false, grid(columns: (width, 1fr), column-gutter: 1.2em, align: horizon,
      box(width: width, height: h * k, {
        place(top + left, image(src, width: width, alt: alt))
        for (i, (label, x, y)) in pins.enumerate() {
          place(top + left, dx: x * k - 0.625em, dy: y * k - 0.625em, pin(i + 1))
        }
      }),
      enum(..pins.map(p => p.at(0)), spacing: 0.7em),
    ))
  }
}

/// A pane's box as it looks: blank in normal mode, `^` in insert, `$` raw
/// (a terminal's own input); `unsaved: true` fills it, as an unsaved
/// file's is. In HTML a span the stylesheet draws, its mode said in words.
#let mode-box(mark, unsaved: false) = {
  let mode = if mark == "^" { "insert" } else if mark == "$" { "raw" } else { "normal" }
  context if html-out() {
    html.elem("span", attrs: (class: "mode-box" + if unsaved { " unsaved" } else { "" },
      role: "img", "aria-label": mode + " mode box" + if unsaved { ", unsaved" } else { "" }), mark)
  } else {
    box(width: 1.05em, height: 1.05em, baseline: 0.15em, radius: 1pt,
      fill: if unsaved { palette.col-grip } else { palette.tag-bg },
      stroke: 0.7pt + palette.grip,
      align(center + horizon, text(font: mono, size: 0.8em, weight: "bold",
        fill: if unsaved { white } else { palette.ink }, mark)))
  }
}

/// A recording from docs/site/media/clips.toml, by name. On the site the
/// same video as the landing's (poster, autoplay muted loop, played while
/// in view) and its caption; in print its poster, small, and the caption.
/// `wide: true` lets it take the page's full width (a recording of many
/// narrow columns).
#let clip(name, wide: false) = {
  let c = toml("../site/media/clips.toml").clip.find(c => c.name == name)
  assert(c != none, message: "no clip named " + name + " in clips.toml")
  let said = if c.caption.contains("#") { eval(c.caption, mode: "markup") } else { c.caption }
  context if html-out() {
    html.elem("figure", attrs: (class: "clip inline" + if wide { " wide" } else { "" }, id: "rec-" + c.name), {
      html.elem("video", attrs: (poster: "media/" + c.name + ".png", autoplay: "", muted: "", loop: "",
        playsinline: "", controls: ""), {
        html.elem("source", attrs: (src: "media/" + c.name + ".webm", type: "video/webm"))
        html.elem("source", attrs: (src: "media/" + c.name + ".mp4", type: "video/mp4"))
      })
      html.elem("figcaption", said)
    })
  } else {
    figure(image("/docs/site/media/" + c.name + ".png", width: if wide { 11cm } else { 7cm }, alt: c.caption),
      caption: text(size: 0.9em, said), numbering: none, kind: "clip", supplement: none)
  }
}