hanzo.ai/components/home/band.tsx

'use client'

// The gui root carries no `'use client'` of its own, so importing a primitive
// from it in a Server Component evaluates gui's module-scope `createContext` in
// the React server build, where that export does not exist — a bare
// "c is not a function" at page-data collection, naming nothing. The boundary
// belongs here, beside the import that needs it.

import { createContext, useContext, type ReactNode } from 'react'
import { Box, Text, View, XStack, YStack } from '@hanzo/ui'
import { Grid } from '@hanzo/ui/grid'
import * as ui from '@hanzo/ui/marketing'
import { INSET } from '@/components/shell/dock'

/**
 * Whether a head stands in the copy column of a `Split`. There, from 1024px,
 * the head is set to the column's starting edge (the right one on a
 * right-to-left page) beside its figure instead of centred over the page, and
 * its actions start where the words do. A context rather than a selector: the
 * head and the row of actions are the components that change, so they are the
 * ones that ask.
 */
const Says = createContext(false)

/**
 * The measure every band on a page takes, when the page states one. Unset, a
 * band reads `--container-max` (@hanzo/design: 80rem). /platform/layers sets
 * 1152 so its apex bands match the deploy-plane bands under them.
 */
export const Measure = createContext<number | undefined>(undefined)

/**
 * The two shapes five apex sections are made of, said once.
 *
 * `SystemArchitecture`, `AgentRuntime`, `LearnLoop`, `Infrastructure` and
 * `OneInterface` each opened with a byte-identical frame — the same measure, the
 * same gutter at the same three widths, the same centred head — written out five
 * times as a cluster of utility classes. One of the five had already drifted:
 * `AgentRuntime` wrapped its section in a `<>…</>` left over from a second
 * section that moved out.
 *
 * This is NOT `page-kit`'s `Section`, and the difference is the design rather
 * than an oversight. That one is left-aligned over a 896 measure and is what
 * every `(marketing)` page wears; this one is centred over 1024 and belongs to
 * the apex. Two shapes, two homes, neither pretending to be the other.
 */

/**
 * The vertical rhythm of a centred band that is not a `Band` — Enso and Score.
 * Each pads top AND bottom, so the gap a reader sees between two is twice this;
 * at the old clamp's ceiling that was 264px, which reads as the page having
 * ended. `max(min())` is `clamp()` spelled the way gui's space type admits.
 */
export const RHYTHM = 'max(48px, min(7vw, 88px))'

/** The page gutter the header and every band share (app/globals.css). */
export const GUTTER_X = 'var(--page-gutter)'


/**
 * A horizontal band of the page: the measure, the gutter and the vertical
 * rhythm.
 *
 * `Box`, not a `YStack`, because a section is a BLOCK — `Box` states
 * `display: block` and a Stack would silently make every band a flex column,
 * which is the defect `@hanzo/ui`'s own note on this component records (77 of
 * 225 elements on one page becoming flex containers nobody asked for).
 *
 * A band with an `id` is a SLIDE: it fills the screen, its content sits at the
 * middle, and the page settles on its top edge. The header's clearance is not
 * this component's: @hanzo/design's base pads every scroll the page makes by
 * `--header`, so a margin here would clear it twice.
 */
export function Band({
  id,
  wide = false,
  children,
}: {
  id?: string
  wide?: boolean
  children: ReactNode
}) {
  const measure = useContext(Measure)
  return (
    <Box
      render="section"
      id={id}
      width="100%"
      /* The rhythm between sections is what a reader feels as calm, and it is
         the one measurement that has to be generous: 120 on a desktop, 80 on a
         phone — the old lux.exchange fold's gap. Tighter and the page reads as
         a list of claims; this reads as one thing with room around it. */
      py={120}
      // On the page's measure and its gutter (components/shell/dock), as the bar is.
      px={INSET}
      $sm={{ py: 80 }}
      minH="100svh"
      display="flex"
      justify="center"
      $platform-web={id ? { scrollSnapAlign: 'start' } : undefined}
    >
      {/* A BLOCK, so every child takes the band's width and a grid among them
          lays its tracks out against a definite size. As flex items, a child
          with auto side margins would shrink to its content instead. */}
      <Box width="100%" maxW={wide ? undefined : measure ?? 'var(--container-max, 1024px)'} mx="auto">
        {children}
      </Box>
    </Box>
  )
}

/**
 * The head of a band: an optional label, the heading, an optional paragraph.
 *
 * A GRID with one column and a gap, not three elements each carrying a margin
 * toward its neighbour. The spacing between them is a property of the STACK —
 * stated once, by the thing that owns the relationship — and a margin on a child
 * is the same fact written from the wrong side, which is why it used to be three
 * different classes (`mb-5`, nothing, `mt-5`) describing one 20px rhythm.
 *
 * Type is @hanzo/ui's `Eyebrow`, `Title` and `Lede` and spacing is this
 * component's, so a call site passes words and never a size.
 *
 * A BAND OPENS ON THREE THINGS AT MOST. There was a fourth — a second heading
 * under the title — and where it was used it read almost as loud as the h2 and
 * argued with it, over a lede that then said the same claim a third time. A name
 * for a band belongs in the eyebrow, above the title, where it introduces rather
 * than competes.
 */

export function Head({
  eyebrow,
  title,
  lede,
  children,
}: {
  eyebrow?: string
  title: string
  lede?: string
  children?: ReactNode
}) {
  const says = useContext(Says)
  return (
    <Grid
      columns={1}
      gap={14}
      width="100%"
      maxW={672}
      mx="auto"
      $platform-web={{ textAlign: 'center' }}
      $lg={says ? { mx: 0, '$platform-web': { textAlign: 'start' } } : undefined}
    >
      {/* The grid's gap is the beat between the three. */}
      {eyebrow ? <ui.Eyebrow>{eyebrow}</ui.Eyebrow> : null}
      <ui.Title>{title}</ui.Title>
      {lede ? <ui.Lede>{lede}</ui.Lede> : null}
      {children}
    </Grid>
  )
}

/**
 * A card's two lines: what it is, then what it does.
 *
 * The pair appears on a layer, a step and a runtime — three sections, one
 * shape. Sizes are the ramp's own rungs, so a reader's type-size preference
 * reaches them.
 *
 * ONE ELEMENT, not a fragment — and the difference is visible the first time
 * this is used the way its own description implies.
 *
 * It used to return two loose siblings, which is fine inside a container that
 * wraps each item and wrong inside every grid: a grid lays out CHILDREN, so a
 * three-column row of these produced six cells and each card's heading landed
 * in a different column from its own body. Measured on the built page — the
 * heading "Connect once" sat over the previous card's text.
 *
 * A component documented as "a card's two lines" should be a card. Wrapping it
 * here means no caller has to know to do it, and the pairing cannot come apart
 * again in the next layout it is dropped into.
 */
export function Note({ title, body }: { title: ReactNode; body: string }) {
  return (
    <YStack>
      <Text fontSize="$3" fontWeight="500" lineHeight="1.3125rem" color="$ink">
        {title}
      </Text>
      <Text mt={4} fontSize="$2" lineHeight="1.3203rem" color="var(--muted-foreground)">
        {body}
      </Text>
    </YStack>
  )
}

/**
 * The page's one button, outlined by default and filled when it is the thing to
 * do. @hanzo/ui's `Action` carries the shape; this carries the link and the
 * press it reports.
 */
export function Action({
  href,
  filled,
  onPress,
  children,
}: {
  href: string
  filled?: boolean
  /** Reports the press; `data-ga` tells the click-out handler (app/providers.tsx) the control reports its own. */
  onPress?: () => void
  children: ReactNode
}) {
  return (
    // The funnel's one button: pay's 56px pill at 16px (hanzo-inc/pay `.pay-cta`).
    <ui.Action href={href} fill={filled} onPress={onPress} data-ga={onPress ? '' : undefined} minH={56} fontSize="1rem">
      {children}
    </ui.Action>
  )
}

/**
 * A row of actions, centred and allowed to wrap.
 *
 * This one stays FLEX, and deliberately: a pair of buttons is a single-axis run
 * whose items size to their own words, which is the one thing flex is for.
 * Making it a grid would give two buttons of different lengths one equal track
 * each and stretch them to match — a worse picture, arrived at by counting a
 * property rather than reading the layout.
 */
export function Actions({ children, top = 36 }: { children: ReactNode; top?: number }) {
  const says = useContext(Says)
  return (
    <XStack mt={top} flexWrap="wrap" items="center" justify="center" gap="$3" $lg={says ? { justify: 'flex-start' } : undefined}>
      {children}
    </XStack>
  )
}

/**
 * Copy beside a figure from 1024px — the copy taking 0.8 of the row and the
 * figure 1.2 — and stacked, copy first and centred, below it.
 */
export function Split({ says, children }: { says: ReactNode; children: ReactNode }) {
  return (
    <View
      display="grid"
      gridTemplateColumns="minmax(0, 1fr)"
      gap={40}
      items="center"
      width="100%"
      $lg={{ gridTemplateColumns: 'minmax(0, 0.8fr) minmax(0, 1.2fr)', gap: 56 }}
    >
      <Says.Provider value>
        <YStack minW={0}>{says}</YStack>
      </Says.Provider>
      <YStack minW={0}>{children}</YStack>
    </View>
  )
}