Page layouts

import * as React from "react"
import {
  ActivityIcon,
  BookOpenIcon,
  FlagIcon,
  GraduationCapIcon,
  ListChecksIcon,
  PencilRulerIcon,
  PlayIcon,
  SparklesIcon,
  StarIcon,
  UsersIcon,
  type LucideIcon,
} from "lucide-react"

import { STUDENT_STATUS_LABELS, STUDENT_STATUS_MAP } from "@/lib/dashboards/academy/vocabulary"
import { formatDate, formatNumber, formatPercent, formatRelative } from "@/lib/format"
import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "@/components/ui/card"
import { DashboardGrid, DashboardGridItem } from "@/components/ui/dashboard-grid"
import { Progress } from "@/components/ui/progress"
import { RankList } from "@/components/ui/rank-list"
import { SimpleTable } from "@/components/ui/simple-table"
import { StatCard } from "@/components/ui/stat-card"
import { StatCardGroup } from "@/components/ui/stat-card-group"
import { StatusBadge } from "@/components/ui/status-badge"
import { UserCell } from "@/components/ui/user-cell"

import { CoursePageFrame } from "./page-layouts-01.client"
import { asOf, coursePage, type CoursePage, type LessonKind } from "./page-layouts-01.data"

const DAY_MS = 86_400_000

/** What each kind of lesson is called, and the mark it wears in the plan. */
const KINDS: Record<LessonKind, { label: string; icon: LucideIcon }> = {
  intro: { label: "Introduction", icon: SparklesIcon },
  video: { label: "Video", icon: PlayIcon },
  exercise: { label: "Exercise", icon: PencilRulerIcon },
  reading: { label: "Reading", icon: BookOpenIcon },
  quiz: { label: "Checkpoint quiz", icon: ListChecksIcon },
  project: { label: "Final project", icon: FlagIcon },
}

/** "3h ago" inside a week; the date itself, in UTC where the data lives, beyond it. */
function lastSeen(date: Date, now: Date): React.ReactNode {
  const text =
    now.getTime() - date.getTime() < 7 * DAY_MS ? formatRelative(date, now) : formatDate(date, "medium", { timeZone: "UTC" })
  return (
    <time dateTime={date.toISOString()} className="tabular-nums">
      {text}
    </time>
  )
}

/** A learner's place on the course: the bar and the figure it draws. */
function ProgressCell({ name, progress }: { name: string; progress: number }) {
  return (
    <div className="flex w-28 items-center gap-2">
      <Progress value={progress} aria-label={`${name}’s progress`} className="flex-1" />
      <span className="w-9 text-right text-xs text-muted-foreground tabular-nums">{progress}%</span>
    </div>
  )
}

function Overview({ page, now }: { page: CoursePage; now: Date }) {
  return (
    <div className="flex flex-col gap-6">
      <StatCardGroup columns={4} divided>
        <StatCard
          label="Enrolled"
          value={formatNumber(page.enrolled)}
          description="since the course opened"
          icon={<UsersIcon aria-hidden="true" />}
        />
        <StatCard
          label="Active this week"
          value={formatNumber(page.activeThisWeek)}
          description={`of ${formatNumber(page.roster)} on the roster`}
          icon={<ActivityIcon aria-hidden="true" />}
        />
        <StatCard
          label="Completion"
          value={formatPercent(page.completionRate, { maximumFractionDigits: 0 })}
          description="of the enrolled finished"
          icon={<GraduationCapIcon aria-hidden="true" />}
        />
        <StatCard
          label="Rating"
          value={page.rating.toFixed(1)}
          description="out of 5 from learners"
          icon={<StarIcon aria-hidden="true" />}
        />
      </StatCardGroup>

      <DashboardGrid>
        <DashboardGridItem colSpan={{ base: 12, lg: 7 }}>
          <Card className="h-full">
            <CardHeader>
              <CardTitle>Where the class is</CardTitle>
              <CardDescription>The roster by how far through the course each learner is</CardDescription>
            </CardHeader>
            <CardContent>
              <RankList
                items={page.bands.map((band) => ({ label: band.label, value: band.learners }))}
                max={page.roster}
                showRank={false}
                format={(value) => `${formatNumber(value)} ${value === 1 ? "learner" : "learners"}`}
              />
            </CardContent>
          </Card>
        </DashboardGridItem>

        <DashboardGridItem colSpan={{ base: 12, lg: 5 }}>
          <Card className="h-full">
            <CardHeader>
              <CardTitle>Recently active</CardTitle>
              <CardDescription>Last seen, newest first</CardDescription>
            </CardHeader>
            <CardContent className="p-0">
              <ul className="divide-y">
                {page.recent.map((learner) => (
                  <li key={learner.id} className="flex items-center gap-3 px-(--card-spacing) py-3">
                    <UserCell
                      name={learner.name}
                      src={learner.avatarUrl}
                      description={lastSeen(learner.lastActiveAt, now)}
                      className="min-w-0 flex-1"
                    />
                    <ProgressCell name={learner.name} progress={learner.progress} />
                  </li>
                ))}
              </ul>
            </CardContent>
          </Card>
        </DashboardGridItem>
      </DashboardGrid>
    </div>
  )
}

function Lessons({ page }: { page: CoursePage }) {
  return (
    <SimpleTable
      className="panel overflow-hidden"
      caption={`${page.lessons} lessons, in the order they are taken, with how many of the ${page.roster} learners are past each`}
      rowKey={(lesson) => String(lesson.number)}
      rows={page.plan}
      columns={[
        { key: "number", header: "#", align: "right", width: "3rem", cell: (lesson) => lesson.number },
        {
          key: "kind",
          header: "Lesson",
          cell: (lesson) => {
            const { label, icon: Icon } = KINDS[lesson.kind]
            return (
              <span className="flex items-center gap-2">
                <Icon aria-hidden="true" className="size-4 text-muted-foreground" />
                {label}
              </span>
            )
          },
        },
        { key: "minutes", header: "Length", align: "right", cell: (lesson) => `${lesson.minutes} min` },
        {
          key: "passed",
          header: "Learners past it",
          align: "right",
          cell: (lesson) => `${formatNumber(lesson.passed)} of ${formatNumber(page.roster)}`,
        },
      ]}
    />
  )
}

function Learners({ page, now }: { page: CoursePage; now: Date }) {
  return (
    <SimpleTable
      className="panel overflow-hidden"
      caption={`Everyone on the course, furthest along first`}
      rowKey="id"
      rows={page.learners}
      columns={[
        {
          key: "name",
          header: "Learner",
          cell: (learner) => <UserCell name={learner.name} email={learner.email} src={learner.avatarUrl} size="sm" />,
        },
        { key: "progress", header: "Progress", cell: (learner) => <ProgressCell name={learner.name} progress={learner.progress} /> },
        {
          key: "status",
          header: "Status",
          cell: (learner) => (
            <StatusBadge status={learner.status} label={STUDENT_STATUS_LABELS[learner.status]} map={STUDENT_STATUS_MAP} />
          ),
        },
        { key: "lastActiveAt", header: "Last seen", align: "right", cell: (learner) => lastSeen(learner.lastActiveAt, now) },
      ]}
    />
  )
}

/**
 * A record page's frame, filled: the trail to one course, the header that
 * names it — whether it is in the catalogue beside the title, what it is and
 * who teaches it, when it last changed — with Copy link and Unpublish on the
 * right and the course's views as tabs on the header's rule. Under them, the
 * view: the course in four figures, the roster by how far through it each
 * learner is and who was in last; the lesson plan; or the whole roster.
 *
 * A server component: it reads the course through `./page-layouts-01.data`,
 * draws each view's panel here and hands the frame island plain strings and
 * those panels.
 */
export function PageLayouts01() {
  const titleId = React.useId()
  const page = coursePage()
  const now = asOf()

  return (
    <section
      data-section="page-layouts-01"
      data-slot="section"
      aria-labelledby={titleId}
      className="w-full bg-background p-4 text-foreground md:p-6"
    >
      <div className="mx-auto max-w-7xl">
        <Card>
          <CardHeader>
            <CardTitle>
              <h2 id={titleId}>Course overview</h2>
            </CardTitle>
            <CardDescription className="tabular-nums">
              Enrolment and progress as of {formatDate(now, "medium", { timeZone: "UTC" })}
            </CardDescription>
          </CardHeader>
          <CardContent className="p-4 md:p-6">
            <CoursePageFrame
              trail={page.trail}
              title={page.title}
              href={page.href}
              description={[
                page.level,
                page.category,
                `${page.lessons} lessons`,
                page.instructor ? `taught by ${page.instructor.name}` : undefined,
              ]
                .filter(Boolean)
                .join(" · ")}
              updated={formatDate(page.updatedAt, "medium", { timeZone: "UTC" })}
              id={page.id}
              views={[
                { value: "overview", title: "Overview", panel: <Overview page={page} now={now} /> },
                { value: "lessons", title: "Lessons", count: page.lessons, panel: <Lessons page={page} /> },
                { value: "learners", title: "Learners", count: page.roster, panel: <Learners page={page} now={now} /> },
              ]}
            />
          </CardContent>
        </Card>
      </div>
    </section>
  )
}

export default PageLayouts01

"use client"

import * as React from "react"
import Link from "next/link"
import { CheckIcon, LinkIcon } from "lucide-react"

import { useCopyToClipboard } from "@/hooks/use-copy-to-clipboard"
import {
  Breadcrumb,
  BreadcrumbItem,
  BreadcrumbLink,
  BreadcrumbList,
  BreadcrumbPage,
  BreadcrumbSeparator,
} from "@/components/ui/breadcrumb"
import { Button } from "@/components/ui/button"
import { PageHeader } from "@/components/ui/page-header"
import { StatusBadge } from "@/components/ui/status-badge"
import { Tabs, TabsContent, TabsList, TabsTrigger } from "@/components/ui/tabs"

import type { PageLink } from "./page-layouts-01.data"

/** One of the course's views: its tab, and the panel the server drew for it. */
export type CourseView = { value: string; title: string; count?: number; panel: React.ReactNode }

export type CoursePageFrameProps = {
  /** From the dashboard's brand to the list the course is opened from. */
  trail: PageLink[]
  title: string
  href: string
  description: string
  /** Already formatted on the server, so the two renders agree. */
  updated: string
  id: string
  views: CourseView[]
}

/**
 * The course page's frame: the trail to it, its name with where it stands
 * beside it, what it is and who teaches it, the two things an author does from
 * here — share it, take it out of the catalogue or put it back — and its views
 * as tabs on the header's rule, each over the panel the server drew. The
 * trail is links, through the router; the tabs switch the panel in place,
 * arrow keys between them. What an action did is said in the header's meta
 * line, which is always there for it.
 */
export function CoursePageFrame({ trail, title, href, description, updated, id, views }: CoursePageFrameProps) {
  const [published, setPublished] = React.useState(true)
  const [notice, setNotice] = React.useState("")
  const { copied, copy } = useCopyToClipboard(2000)

  // The line only ever claims what happened: a copy the browser refused
  // leaves it as it was, and the icon never turns to a tick.
  async function share() {
    if (await copy(new URL(href, window.location.origin).toString())) setNotice("Link copied.")
  }

  function togglePublished() {
    const next = !published
    setPublished(next)
    setNotice(
      next
        ? "Published: back in the catalogue."
        : "Unpublished: learners on the roster keep their place and their progress."
    )
  }

  return (
    <Tabs defaultValue={views[0]?.value} className="gap-6">
      <div className="flex flex-col gap-3">
        <Breadcrumb aria-label="Course breadcrumb">
          <BreadcrumbList>
            {trail.map((crumb) => (
              <React.Fragment key={crumb.href}>
                <BreadcrumbItem>
                  <BreadcrumbLink render={<Link href={crumb.href} />}>{crumb.title}</BreadcrumbLink>
                </BreadcrumbItem>
                <BreadcrumbSeparator />
              </React.Fragment>
            ))}
            <BreadcrumbItem className="min-w-0">
              <BreadcrumbPage className="truncate">{title}</BreadcrumbPage>
            </BreadcrumbItem>
          </BreadcrumbList>
        </Breadcrumb>

        <PageHeader
          as="h3"
          title={title}
          badge={<StatusBadge status={published ? "Published" : "Draft"} map={{ published: "success" }} />}
          description={description}
          meta={
            <>
              <span className="tabular-nums">Updated {updated}</span>
              <span className="font-mono">{id}</span>
              <span role="status" aria-live="polite">
                {notice}
              </span>
            </>
          }
          actions={
            <>
              <Button type="button" variant="outline" size="sm" onClick={share}>
                {copied ? <CheckIcon aria-hidden="true" /> : <LinkIcon aria-hidden="true" />}
                Copy link
              </Button>
              <Button
                type="button"
                size="sm"
                variant={published ? "outline" : "default"}
                onClick={togglePublished}
              >
                {published ? "Unpublish" : "Publish"}
              </Button>
            </>
          }
          tabs={
            // The panels are drawn already, so an arrow key shows its tab's at once.
            <TabsList variant="line" aria-label="Course views" activateOnFocus className="max-w-full overflow-x-auto">
              {views.map((view) => (
                <TabsTrigger key={view.value} value={view.value} className="flex-none">
                  {view.title}
                  {/* A space the flex row does not draw, so the name reads
                      "Lessons 11" rather than running the two together. */}
                  {view.count !== undefined ? " " : null}
                  {view.count !== undefined ? (
                    <span className="rounded-full bg-muted px-1.5 py-0.5 text-2xs text-muted-foreground tabular-nums">
                      {view.count}
                    </span>
                  ) : null}
                </TabsTrigger>
              ))}
            </TabsList>
          }
        />
      </div>

      {views.map((view) => (
        <TabsContent key={view.value} value={view.value}>
          {view.panel}
        </TabsContent>
      ))}
    </Tabs>
  )
}

/**
 * What `page-layouts-01` reads: one course of the academy and the people
 * around it — the `db.courses` row, the `db.members` row that teaches it and
 * the `db.students` holding a place on it. The course is the catalogue's
 * busiest, the one with the most learners ever enrolled; a page of your own
 * reads the course its route names instead. The trail comes from the Academy
 * dashboard's own nav, and "this week" is the seven days up to
 * `REFERENCE_DATE`.
 *
 * `Course` records how many lessons it has, not what they are, so the lesson
 * plan is a rule over that count, scattered once by
 * `seeded("page-layouts-01/<id>")`: an introduction first, a checkpoint quiz
 * every fifth lesson, a final project last, and videos, exercises and readings
 * between. A learner is past a lesson when their progress covers it —
 * progress × lessons ÷ 100, rounded down.
 *
 * Selectors only, reading `db` inside functions and run on the server. The
 * island takes what they return as props; it never imports this module.
 */
import { breadcrumbsFor } from "@/lib/nav-config"
import { NAV } from "@/lib/dashboards/academy/nav"
import { CATEGORY_LABELS, LEVEL_LABELS, courseHref } from "@/lib/dashboards/academy/vocabulary"
import { REFERENCE_DATE, db, intBetween, pickWeighted, seeded, type Course, type Student } from "@/lib/sample-data"

const DAY_MS = 86_400_000

/** A crumb or a tab: where it goes, and what it is called. */
export type PageLink = { title: string; href: string }

/** How far through the course a slice of its roster is. */
export type ProgressBand = { label: string; learners: number }

export type RecentLearner = {
  id: string
  name: string
  avatarUrl: string
  /** Through this course, as a whole percentage. */
  progress: number
  lastActiveAt: Date
}

export type Learner = RecentLearner & { email: string; status: Student["status"] }

export type LessonKind = "intro" | "video" | "exercise" | "reading" | "quiz" | "project"

export type Lesson = {
  number: number
  kind: LessonKind
  minutes: number
  /** Learners on the roster past this lesson. */
  passed: number
}

export type CoursePage = {
  id: string
  title: string
  href: string
  category: string
  level: string
  lessons: number
  instructor: { name: string; avatarUrl?: string } | undefined
  updatedAt: Date
  /** From the dashboard's brand to the list the course is opened from; the course itself is the page. */
  trail: PageLink[]
  /** Everyone ever enrolled, the catalogue's own count. */
  enrolled: number
  /** The share of the enrolled who finished, 0–1. */
  completionRate: number
  /** Out of five. */
  rating: number
  /** Learners holding a place now. */
  roster: number
  /** Of those, the ones seen in the last seven days. */
  activeThisWeek: number
  bands: ProgressBand[]
  recent: RecentLearner[]
  /** The whole roster, furthest along first. */
  learners: Learner[]
  /** The lessons in the order they are taken. */
  plan: Lesson[]
}

/** The slices a roster is read in, by progress: never opened, four quarters, and done. */
const BANDS: { label: string; from: number; to: number }[] = [
  { label: "Not started", from: 0, to: 0 },
  { label: "Under a quarter", from: 1, to: 24 },
  { label: "A quarter to half", from: 25, to: 49 },
  { label: "Half to three quarters", from: 50, to: 74 },
  { label: "Nearly there", from: 75, to: 99 },
  { label: "Finished", from: 100, to: 100 },
]

/** What sits between the introduction and the final project, and how often. */
const MIDDLE: readonly (readonly [LessonKind, number])[] = [
  ["video", 0.5],
  ["exercise", 0.3],
  ["reading", 0.2],
]

/** How long each kind of lesson runs, in minutes: the least and the most. */
const MINUTES: Record<LessonKind, [number, number]> = {
  intro: [4, 8],
  video: [8, 18],
  exercise: [15, 30],
  reading: [6, 12],
  quiz: [5, 10],
  project: [45, 90],
}

/** The course's lessons in order, and how many of its learners are past each. */
function lessonPlan(course: Course, progress: number[]): Lesson[] {
  const rand = seeded(`page-layouts-01/${course.id}`)
  return Array.from({ length: course.lessons }, (_, index) => {
    const number = index + 1
    const kind: LessonKind =
      number === 1 ? "intro" : number === course.lessons ? "project" : number % 5 === 0 ? "quiz" : pickWeighted(rand, MIDDLE)
    const [least, most] = MINUTES[kind]
    return {
      number,
      kind,
      minutes: intBetween(rand, least, most),
      passed: progress.filter((percent) => Math.floor((percent * course.lessons) / 100) >= number).length,
    }
  })
}

/** The course with the most learners ever enrolled; ties go to the earlier id. */
function featuredCourse(): Course {
  const [first, ...rest] = db.courses.all()
  return rest.reduce((best, course) => (course.enrolled > best.enrolled ? course : best), first)
}

/** The course page the band draws, gathered in one read. */
export function coursePage(): CoursePage {
  const course = featuredCourse()
  const href = courseHref(course.id)
  const teacher = db.members.all().find((member) => member.id === course.instructorId)
  const places = db.students.all().flatMap((student) =>
    student.enrolled
      .filter((place) => place.courseId === course.id)
      .map((place) => ({ student, progress: place.progress }))
  )
  const weekAgo = REFERENCE_DATE.getTime() - 7 * DAY_MS

  return {
    id: course.id,
    title: course.title,
    href,
    category: CATEGORY_LABELS[course.category],
    level: LEVEL_LABELS[course.level],
    lessons: course.lessons,
    instructor: teacher ? { name: teacher.name, avatarUrl: teacher.avatarUrl } : undefined,
    updatedAt: course.updatedAt,
    // The nav resolves a course's route to Courses, the list it is opened from.
    trail: breadcrumbsFor(NAV, href),
    enrolled: course.enrolled,
    completionRate: course.completionRate,
    rating: course.rating,
    roster: places.length,
    activeThisWeek: places.filter(({ student }) => student.lastActiveAt.getTime() >= weekAgo).length,
    bands: BANDS.map((band) => ({
      label: band.label,
      learners: places.filter(({ progress }) => progress >= band.from && progress <= band.to).length,
    })),
    recent: [...places]
      .sort((a, b) => b.student.lastActiveAt.getTime() - a.student.lastActiveAt.getTime())
      .slice(0, 5)
      .map(({ student, progress }) => ({
        id: student.id,
        name: student.name,
        avatarUrl: student.avatarUrl,
        progress,
        lastActiveAt: student.lastActiveAt,
      })),
    learners: [...places]
      .sort((a, b) => b.progress - a.progress || a.student.name.localeCompare(b.student.name))
      .map(({ student, progress }) => ({
        id: student.id,
        name: student.name,
        email: student.email,
        avatarUrl: student.avatarUrl,
        progress,
        lastActiveAt: student.lastActiveAt,
        status: student.status,
      })),
    plan: lessonPlan(
      course,
      places.map(({ progress }) => progress)
    ),
  }
}

/** "Now" for the band's relative times: the store's reference date, never the clock. */
export function asOf(): Date {
  return REFERENCE_DATE
}

import * as React from "react"

import { formatDuration } from "@/lib/format"
import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "@/components/ui/card"
import { StatusBadge, type StatusVariant } from "@/components/ui/status-badge"
import { UptimeBar, type UptimeDayStatus } from "@/components/ui/uptime-bar"
import { UserCell } from "@/components/ui/user-cell"

import { IncidentPage } from "./page-layouts-02.client"
import {
  DEPLOY_WINDOW_HOURS,
  UPTIME_DAYS,
  asOf,
  incidentRecord,
  type AffectedService,
  type IncidentRecord,
  type RecentDeploy,
} from "./page-layouts-02.data"

/** "Sep 1, 09:19": the day and the time, on the 24-hour clock, in UTC where the data lives. */
const WHEN = new Intl.DateTimeFormat("en-US", {
  month: "short",
  day: "numeric",
  hour: "2-digit",
  minute: "2-digit",
  hourCycle: "h23",
  timeZone: "UTC",
})

/** What each severity is called beside its code. */
const SEVERITY: Record<IncidentRecord["severity"], string> = { sev1: "Critical", sev2: "Major", sev3: "Minor" }

/** How a service stands now, in the words and tones a status page uses. */
const SERVICE_STATUS: Record<AffectedService["status"], { label: string; tone: StatusVariant }> = {
  operational: { label: "Operational", tone: "success" },
  degraded: { label: "Degraded", tone: "warning" },
  partial_outage: { label: "Partial outage", tone: "warning" },
  major_outage: { label: "Major outage", tone: "danger" },
  maintenance: { label: "Maintenance", tone: "info" },
}

const DEPLOY_STATUS: Record<RecentDeploy["status"], StatusVariant> = {
  success: "success",
  failed: "danger",
  running: "info",
  cancelled: "neutral",
}

/** A day's bar, by the Engineering dashboard's rule: up from 99.5%, degraded down to 97%, down below it. */
function dayStatus(uptime: number): UptimeDayStatus {
  return uptime >= 99.5 ? "up" : uptime >= 97 ? "degraded" : "down"
}

/** What the probes measured over the run, to two places — not a count of good and bad days. */
function measured(days: AffectedService["days"]): number {
  return Math.round((days.reduce((total, day) => total + day.uptime, 0) / days.length) * 100) / 100
}

function ServicesCard({ services }: { services: AffectedService[] }) {
  return (
    <Card>
      <CardHeader>
        <CardTitle>Affected services</CardTitle>
        <CardDescription>How each stands now, and its last {UPTIME_DAYS} days</CardDescription>
      </CardHeader>
      <CardContent className="flex flex-col gap-5">
        {services.map((service) => {
          const status = SERVICE_STATUS[service.status]
          return (
            <div key={service.id} className="flex flex-col gap-3">
              <div className="flex flex-wrap items-center justify-between gap-2">
                <div className="flex min-w-0 items-baseline gap-2">
                  <span className="font-medium">{service.name}</span>
                  <span className="font-mono text-xs text-muted-foreground">{service.region}</span>
                </div>
                <StatusBadge status={service.status} label={status.label} variant={status.tone} />
              </div>
              <UptimeBar
                size="sm"
                uptime={measured(service.days)}
                labelText={`${service.name}, last ${UPTIME_DAYS} days`}
                days={service.days.map((day) => ({
                  date: day.date,
                  status: dayStatus(day.uptime),
                  label: `${day.uptime.toFixed(2)}% up`,
                }))}
              />
            </div>
          )
        })}
      </CardContent>
    </Card>
  )
}

function DeploysCard({ deploys, startedAt }: { deploys: RecentDeploy[]; startedAt: Date }) {
  return (
    <Card>
      <CardHeader>
        <CardTitle>Deploys before it began</CardTitle>
        <CardDescription>Production, the {DEPLOY_WINDOW_HOURS} hours before</CardDescription>
      </CardHeader>
      <CardContent className={deploys.length ? "p-0" : undefined}>
        {deploys.length ? (
          <ul className="divide-y">
            {deploys.map((deploy) => (
              <li key={deploy.id} className="flex flex-col gap-1 px-(--card-spacing) py-3">
                <div className="flex items-center justify-between gap-2">
                  <span className="min-w-0 truncate font-mono text-xs">{deploy.branch}</span>
                  <StatusBadge status={deploy.status} variant={DEPLOY_STATUS[deploy.status]} size="sm" />
                </div>
                <div className="flex flex-wrap gap-x-2 text-xs text-muted-foreground">
                  <span className="font-mono">{deploy.sha}</span>
                  <span>{deploy.author}</span>
                  <span className="tabular-nums">
                    {formatDuration(startedAt.getTime() - deploy.startedAt.getTime())} before
                  </span>
                </div>
              </li>
            ))}
          </ul>
        ) : (
          <p className="text-sm text-muted-foreground">Nothing went to production in that window.</p>
        )}
      </CardContent>
    </Card>
  )
}

/**
 * A detail page: one incident, its story in the main column and its facts in
 * the aside. Over both, the trail back to Incidents and the header — the
 * incident's title with where it stands, what it affects, when it began and
 * how bad it is — with the two things a commander does from here: write an
 * update, and resolve it. The main column is the timeline under a form that
 * posts to it, then the affected services with their last thirty days; the
 * aside, the details and the deploys that went out just before it began.
 *
 * A server component: it reads the incident through `./page-layouts-02.data`,
 * writes every time out in UTC here, and draws the two cards that do not
 * change; the island holds the timeline and everything that follows it.
 */
export function PageLayouts02() {
  const titleId = React.useId()
  const record = incidentRecord()
  const now = asOf()

  return (
    <section
      data-section="page-layouts-02"
      data-slot="section"
      aria-labelledby={titleId}
      className="w-full bg-background p-4 text-foreground md:p-6"
    >
      <div className="mx-auto max-w-7xl">
        <Card>
          <CardHeader>
            <CardTitle>
              <h2 id={titleId}>Incident</h2>
            </CardTitle>
            <CardDescription className="tabular-nums">
              Northwind Platform, as of {WHEN.format(now)} UTC
            </CardDescription>
          </CardHeader>
          <CardContent className="p-4 md:p-6">
            <IncidentPage
              trail={record.trail}
              id={record.id}
              title={record.title}
              severity={{ code: record.severity.toUpperCase(), label: SEVERITY[record.severity] }}
              started={WHEN.format(record.startedAt)}
              startedAt={record.startedAt.getTime()}
              updates={record.updates.map((update) => ({
                at: update.at.getTime(),
                when: WHEN.format(update.at),
                status: update.status,
                message: update.message,
              }))}
              now={now.getTime()}
              nowWhen={WHEN.format(now)}
              services={record.services.map((service) => service.name)}
              commander={
                record.commander ? (
                  <UserCell name={record.commander.name} email={record.commander.email} src={record.commander.avatarUrl} size="sm" />
                ) : (
                  "Unassigned"
                )
              }
              servicesCard={<ServicesCard services={record.services} />}
              deploysCard={<DeploysCard deploys={record.deploys} startedAt={record.startedAt} />}
            />
          </CardContent>
        </Card>
      </div>
    </section>
  )
}

export default PageLayouts02

"use client"

import * as React from "react"
import Link from "next/link"
import { CheckIcon, CrosshairIcon, EyeIcon, SearchIcon, type LucideIcon } from "lucide-react"

import { formatDuration } from "@/lib/format"
import {
  Breadcrumb,
  BreadcrumbItem,
  BreadcrumbLink,
  BreadcrumbList,
  BreadcrumbPage,
  BreadcrumbSeparator,
} from "@/components/ui/breadcrumb"
import { Button } from "@/components/ui/button"
import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "@/components/ui/card"
import { DescriptionList } from "@/components/ui/description-list"
import { Field, FieldError, FieldLabel } from "@/components/ui/field"
import { NativeSelect, NativeSelectOption } from "@/components/ui/native-select"
import { PageHeader } from "@/components/ui/page-header"
import { StatusBadge, type StatusVariant } from "@/components/ui/status-badge"
import { Textarea } from "@/components/ui/textarea"
import { Timeline, TimelineItem, type TimelineTone } from "@/components/ui/timeline"

import type { IncidentStatus } from "./page-layouts-02.data"

/** Where an incident stands, in the order it gets there, and how each stage reads. */
const STAGES: Record<IncidentStatus, { label: string; tone: StatusVariant & TimelineTone; icon: LucideIcon }> = {
  investigating: { label: "Investigating", tone: "danger", icon: SearchIcon },
  identified: { label: "Identified", tone: "warning", icon: CrosshairIcon },
  monitoring: { label: "Monitoring", tone: "info", icon: EyeIcon },
  resolved: { label: "Resolved", tone: "success", icon: CheckIcon },
}
const ORDER = Object.keys(STAGES) as IncidentStatus[]
const TONES = Object.fromEntries(ORDER.map((stage) => [stage, STAGES[stage].tone]))

/** An update as the island draws it: when is written out on the server, in UTC. */
export type TimelineEntry = { at: number; when: string; status: IncidentStatus; message: string }

export type IncidentPageProps = {
  trail: { title: string; href: string }[]
  id: string
  title: string
  /** The code a pager prints — "SEV2" — and what it means. */
  severity: { code: string; label: string }
  started: string
  startedAt: number
  /** Oldest first. */
  updates: TimelineEntry[]
  /** The page's "now", and the same instant written out. */
  now: number
  nowWhen: string
  services: string[]
  commander: React.ReactNode
  /** The two cards that do not change here, drawn on the server. */
  servicesCard: React.ReactNode
  deploysCard: React.ReactNode
}

/**
 * The incident page: the trail to it, the header that names it with where it
 * stands and how bad it is, and two actions — write an update, or resolve it
 * (reopen it, once resolved). The main column is the timeline, newest first,
 * under a form that posts to it: the words are required, and the stage the
 * update moves the incident to is chosen beside them; the header, the details
 * and the duration follow what was posted. The aside is the facts and the
 * deploys that went out just before it began.
 */
export function IncidentPage(props: IncidentPageProps) {
  const { trail, id, title, severity, started, startedAt, now, nowWhen, services, commander } = props
  const [updates, setUpdates] = React.useState(props.updates)
  const [message, setMessage] = React.useState("")
  const [next, setNext] = React.useState<IncidentStatus>(() => nextStage(props.updates.at(-1)?.status))
  const [error, setError] = React.useState("")
  const [notice, setNotice] = React.useState("")
  const messageRef = React.useRef<HTMLTextAreaElement>(null)
  const messageId = React.useId()
  const errorId = React.useId()
  const stageId = React.useId()

  const status = updates.at(-1)?.status ?? "investigating"
  const resolved = status === "resolved"
  const stage = STAGES[status]
  const lasted = formatDuration(((resolved ? updates.at(-1)?.at : undefined) ?? now) - startedAt)

  function append(entry: Omit<TimelineEntry, "at" | "when">) {
    setUpdates((current) => [...current, { ...entry, at: now, when: nowWhen }])
    setNext(nextStage(entry.status))
    setNotice(`Posted at ${nowWhen} UTC: ${STAGES[entry.status].label}.`)
  }

  function post(event: React.FormEvent) {
    event.preventDefault()
    const words = message.trim()
    if (!words) {
      setError("Write what changed before posting.")
      messageRef.current?.focus()
      return
    }
    setError("")
    setMessage("")
    append({ status: next, message: words })
  }

  return (
    <div className="flex flex-col gap-6">
      <div className="flex flex-col gap-3">
        <Breadcrumb aria-label="Incident breadcrumb">
          <BreadcrumbList>
            {trail.map((crumb) => (
              <React.Fragment key={crumb.href}>
                <BreadcrumbItem>
                  <BreadcrumbLink render={<Link href={crumb.href} />}>{crumb.title}</BreadcrumbLink>
                </BreadcrumbItem>
                <BreadcrumbSeparator />
              </React.Fragment>
            ))}
            <BreadcrumbItem>
              <BreadcrumbPage className="font-mono">{id}</BreadcrumbPage>
            </BreadcrumbItem>
          </BreadcrumbList>
        </Breadcrumb>
        <PageHeader
          as="h3"
          title={title}
          badge={<StatusBadge status={status} label={stage.label} map={TONES} />}
          description={`Affecting ${services.join(" and ")}`}
          meta={
            <>
              <span className="tabular-nums">Started {started} UTC</span>
              <Severity {...severity} />
            </>
          }
          actions={
            <>
              <Button type="button" variant="outline" size="sm" onClick={() => messageRef.current?.focus()}>
                Write an update
              </Button>
              <Button
                type="button"
                size="sm"
                variant={resolved ? "outline" : "default"}
                onClick={() =>
                  append(
                    resolved
                      ? { status: "investigating", message: "Reopened: the problem is back, and we are investigating." }
                      : { status: "resolved", message: "This incident has been resolved." }
                  )
                }
              >
                {resolved ? "Reopen" : "Resolve"}
              </Button>
            </>
          }
        />
      </div>

      <div className="grid gap-6 lg:grid-cols-12">
        <div className="flex min-w-0 flex-col gap-6 lg:col-span-8">
          <Card>
            <CardHeader>
              <CardTitle>Timeline</CardTitle>
              <CardDescription>Every update, newest first</CardDescription>
            </CardHeader>
            <CardContent className="flex flex-col gap-6">
              <form onSubmit={post} noValidate className="flex flex-col gap-3">
                <Field data-invalid={error ? "true" : undefined}>
                  <FieldLabel htmlFor={messageId}>Update</FieldLabel>
                  <Textarea
                    ref={messageRef}
                    id={messageId}
                    rows={3}
                    value={message}
                    onChange={(event) => setMessage(event.target.value)}
                    placeholder="What changed, and what happens next"
                    aria-invalid={error ? true : undefined}
                    aria-describedby={error ? errorId : undefined}
                  />
                  <FieldError id={errorId}>{error}</FieldError>
                </Field>
                <div className="flex flex-wrap items-end justify-between gap-3">
                  <Field className="w-auto">
                    <FieldLabel htmlFor={stageId}>Moves it to</FieldLabel>
                    <NativeSelect id={stageId} value={next} onChange={(event) => setNext(event.target.value as IncidentStatus)}>
                      {ORDER.map((option) => (
                        <NativeSelectOption key={option} value={option}>
                          {STAGES[option].label}
                        </NativeSelectOption>
                      ))}
                    </NativeSelect>
                  </Field>
                  <Button type="submit">Post update</Button>
                </div>
                <p role="status" aria-live="polite" className="text-sm text-muted-foreground">
                  {notice}
                </p>
              </form>

              <Timeline aria-label="Updates, newest first">
                {[...updates].reverse().map((update, index) => {
                  const { label, tone, icon: Icon } = STAGES[update.status]
                  return (
                    <TimelineItem
                      key={`${update.at}-${updates.length - index}`}
                      tone={tone}
                      icon={<Icon aria-hidden="true" />}
                      title={label}
                      time={
                        <time dateTime={new Date(update.at).toISOString()}>
                          <span className="sr-only">, </span>
                          {update.when} UTC
                        </time>
                      }
                      description={update.message}
                    />
                  )
                })}
              </Timeline>
            </CardContent>
          </Card>
          {props.servicesCard}
        </div>

        <aside aria-label="Incident details" className="flex min-w-0 flex-col gap-6 lg:col-span-4">
          <Card>
            <CardHeader>
              <CardTitle>Details</CardTitle>
            </CardHeader>
            <CardContent>
              <DescriptionList
                orientation="vertical"
                items={[
                  { term: "Status", description: <StatusBadge status={status} label={stage.label} map={TONES} /> },
                  { term: "Severity", description: <Severity {...severity} /> },
                  { term: "Commander", description: commander },
                  { term: "Started", description: <span className="tabular-nums">{started} UTC</span> },
                  { term: resolved ? "Lasted" : "Open for", description: <span className="tabular-nums">{lasted}</span> },
                  { term: "Services", description: services.join(", ") },
                ]}
              />
            </CardContent>
          </Card>
          {props.deploysCard}
        </aside>
      </div>
    </div>
  )
}

/** "SEV3 · Minor": the code in the mono face ids and codes wear, and its meaning in words. */
function Severity({ code, label }: { code: string; label: string }) {
  return (
    <span>
      <span className="font-mono">{code}</span> · {label}
    </span>
  )
}

/** The stage an update moves an incident on to: the one after where it stands, or where it is once resolved. */
function nextStage(current: IncidentStatus | undefined): IncidentStatus {
  if (!current) return "investigating"
  return ORDER[Math.min(ORDER.indexOf(current) + 1, ORDER.length - 1)]
}

/**
 * What `page-layouts-02` reads: one incident on the platform and what stands
 * around it — the `db.incidents` row with its timeline of updates, the
 * `db.services` it affects with their last thirty days, the `db.members` row
 * running point, and the `db.deployments` that went to production in the two
 * days before it began, the first place anyone looks. The incident is the open
 * one with the longest timeline, the latest of those on a tie; a page of your
 * own reads the one its route names. "Now" is `REFERENCE_DATE`.
 *
 * Selectors only, reading `db` inside functions and run on the server. The
 * island takes what they return as props; it never imports this module.
 */
import { breadcrumbsFor } from "@/lib/nav-config"
import { NAV, ROUTES } from "@/lib/dashboards/engineering/nav"
import { REFERENCE_DATE, db, type Deployment, type Incident, type Service } from "@/lib/sample-data"

const DAY_MS = 86_400_000
const HOUR_MS = 3_600_000

/** How far back the deploys are read from the moment the incident began. */
export const DEPLOY_WINDOW_HOURS = 48
/** How many days of each service's record the page draws. */
export const UPTIME_DAYS = 30

export type IncidentStatus = Incident["status"]
export type IncidentUpdate = { at: Date; status: IncidentStatus; message: string }

export type AffectedService = {
  id: string
  name: string
  region: string
  status: Service["status"]
  /** One a day, oldest first, ending on `REFERENCE_DATE`: the share of the day it was up, 0–100. */
  days: { date: Date; uptime: number }[]
}

export type RecentDeploy = Pick<Deployment, "id" | "sha" | "branch" | "author" | "status" | "startedAt" | "durationSec">

export type IncidentRecord = {
  id: string
  title: string
  severity: Incident["severity"]
  status: IncidentStatus
  startedAt: Date
  resolvedAt?: Date
  /** Oldest first, the way it happened. */
  updates: IncidentUpdate[]
  commander: { name: string; email: string; avatarUrl?: string } | undefined
  services: AffectedService[]
  deploys: RecentDeploy[]
  /** From the dashboard's brand to Incidents, the list an incident is opened from. */
  trail: { title: string; href: string }[]
}

/** The open incident with the most updates behind it; of equals, the one that began last. */
function featuredIncident(): Incident {
  const incidents = db.incidents.all()
  const open = incidents.filter((incident) => incident.status !== "resolved")
  return [...(open.length ? open : incidents)].sort(
    (a, b) => b.updates.length - a.updates.length || b.startedAt.getTime() - a.startedAt.getTime()
  )[0]
}

/** The incident page the band draws, gathered in one read. */
export function incidentRecord(): IncidentRecord {
  const incident = featuredIncident()
  const commander = db.members.all().find((member) => member.id === incident.commander)
  const began = incident.startedAt.getTime()
  const today = Date.UTC(REFERENCE_DATE.getUTCFullYear(), REFERENCE_DATE.getUTCMonth(), REFERENCE_DATE.getUTCDate())

  return {
    id: incident.id,
    title: incident.title,
    severity: incident.severity,
    status: incident.status,
    startedAt: incident.startedAt,
    resolvedAt: incident.resolvedAt,
    updates: [...incident.updates].sort((a, b) => a.at.getTime() - b.at.getTime()),
    commander: commander ? { name: commander.name, email: commander.email, avatarUrl: commander.avatarUrl } : undefined,
    services: db.services
      .all()
      .filter((service) => incident.serviceIds.includes(service.id))
      .map((service) => ({
        id: service.id,
        name: service.name,
        region: service.region,
        status: service.status,
        days: service.uptime90d.slice(-UPTIME_DAYS).map((uptime, index, days) => ({
          date: new Date(today - (days.length - 1 - index) * DAY_MS),
          uptime,
        })),
      })),
    deploys: db.deployments
      .all()
      .filter(
        (deploy) =>
          deploy.environment === "production" &&
          deploy.startedAt.getTime() <= began &&
          deploy.startedAt.getTime() > began - DEPLOY_WINDOW_HOURS * HOUR_MS
      )
      .sort((a, b) => b.startedAt.getTime() - a.startedAt.getTime())
      .map(({ id, sha, branch, author, status, startedAt, durationSec }) => ({
        id,
        sha,
        branch,
        author,
        status,
        startedAt,
        durationSec,
      })),
    trail: breadcrumbsFor(NAV, `${ROUTES.incidents}/${incident.id}`),
  }
}

/** "Now" for the page: the store's reference date, never the clock. */
export function asOf(): Date {
  return REFERENCE_DATE
}

import * as React from "react"

import { formatBytes, formatNumber, getInitials } from "@/lib/format"
import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "@/components/ui/card"

import { InboxSplit, type InboxRow } from "./page-layouts-03.client"
import { asOf, inboxPage, type InboxMail } from "./page-layouts-03.data"

/** "20:47": the time on the 24-hour clock, in UTC where the data lives. */
const TIME = new Intl.DateTimeFormat("en-US", { hour: "2-digit", minute: "2-digit", hourCycle: "h23", timeZone: "UTC" })
/** "Sep 3". */
const DAY = new Intl.DateTimeFormat("en-US", { month: "short", day: "numeric", timeZone: "UTC" })
/** "Sep 3, 2026, 20:47". */
const SENT = new Intl.DateTimeFormat("en-US", {
  month: "short",
  day: "numeric",
  year: "numeric",
  hour: "2-digit",
  minute: "2-digit",
  hourCycle: "h23",
  timeZone: "UTC",
})

const sameDay = (a: Date, b: Date) => a.toISOString().slice(0, 10) === b.toISOString().slice(0, 10)

/** A mail as the island draws it, every date and size written out here. */
function row(mail: InboxMail, now: Date, reader: { name: string; email: string }): InboxRow {
  // The body opens on its greeting; the first paragraph after it is what a list shows.
  const [, first = mail.body[0] ?? ""] = mail.body
  return {
    id: mail.id,
    from: { ...mail.from, initials: getInitials(mail.from.name) },
    to: mail.to.map((address) => (address === reader.email ? reader.name : address)).join(", "),
    subject: mail.subject,
    preview: first,
    paragraphs: mail.body,
    when: sameDay(mail.at, now) ? TIME.format(mail.at) : DAY.format(mail.at),
    sent: `${SENT.format(mail.at)} UTC`,
    read: mail.read,
    starred: mail.starred,
    labels: mail.labels,
    attachments: mail.attachments.map((file) => ({ name: file.name, size: formatBytes(file.sizeBytes, 1) })),
  }
}

/**
 * A list and the thing picked from it, side by side: the newest page of one
 * inbox beside the mail it has open. The list says how much is unread and
 * walks with the arrow keys; the reading pane holds the whole mail with Star,
 * Mark unread and Archive; the divider between the two drags, and on a phone
 * the two take turns behind a Back button.
 *
 * A server component: it reads the page through `./page-layouts-03.data` and
 * writes every date and size out here, so the island gets plain strings. The
 * mail open at first is the newest one already read, so drawing the band
 * reads nothing on the reader's behalf.
 */
export function PageLayouts03() {
  const titleId = React.useId()
  const page = inboxPage()
  const now = asOf()
  const rows = page.mails.map((mail) => row(mail, now, page.reader))

  return (
    <section
      data-section="page-layouts-03"
      data-slot="section"
      aria-labelledby={titleId}
      className="w-full bg-background p-4 text-foreground md:p-6"
    >
      <div className="mx-auto max-w-7xl">
        <Card>
          <CardHeader>
            <CardTitle>
              <h2 id={titleId}>Inbox</h2>
            </CardTitle>
            <CardDescription className="tabular-nums">
              {page.reader.name} · {formatNumber(page.unread)} unread of {formatNumber(page.total)}
            </CardDescription>
          </CardHeader>
          <CardContent className="p-3 md:p-4">
            <InboxSplit mails={rows} total={page.total} initialId={rows.find((mail) => mail.read)?.id} />
          </CardContent>
        </Card>
      </div>
    </section>
  )
}

export default PageLayouts03

"use client"

import * as React from "react"
import { ArchiveIcon, MailIcon, MailOpenIcon, PaperclipIcon, StarIcon } from "lucide-react"

import { cn } from "@/lib/utils"
import { Avatar, AvatarFallback, AvatarImage } from "@/components/ui/avatar"
import { Badge } from "@/components/ui/badge"
import { Button } from "@/components/ui/button"
import { SplitView } from "@/components/ui/split-view"

/** A mail as the island draws it: every date and size is written out on the server. */
export type InboxRow = {
  id: string
  from: { name: string; email: string; avatarUrl: string; initials: string }
  /** Who it went to, as names or addresses. */
  to: string
  subject: string
  /** The first paragraph after the greeting: what a row shows under the subject. */
  preview: string
  paragraphs: string[]
  /** "20:47" for today, "Sep 3" before it. */
  when: string
  /** "Sep 3, 2026, 20:47 UTC". */
  sent: string
  read: boolean
  starred: boolean
  labels: string[]
  attachments: { name: string; size: string }[]
}

export type InboxSplitProps = {
  mails: InboxRow[]
  /** Everything in the inbox, of which `mails` is the newest page. */
  total: number
  /** The mail open when the band first draws: the newest one already read. */
  initialId?: string
}

/**
 * The inbox as a list and a reading pane. The list is a listbox — one tab
 * stop, the arrow keys, Home and End walk it and the mail under the cursor
 * opens beside it — and a mail opened is a mail read. The pane reads the mail
 * out in full with three things to do to it: star it, put it back to unread,
 * archive it, after which the next mail opens. On a phone the two take turns,
 * the kit's SplitView putting a Back button over the mail. What an action did
 * is said in the status line under the split.
 */
export function InboxSplit({ mails, total, initialId }: InboxSplitProps) {
  const [rows, setRows] = React.useState(mails)
  const [selectedId, setSelectedId] = React.useState(initialId ?? mails[0]?.id)
  const [showDetail, setShowDetail] = React.useState(false)
  const [notice, setNotice] = React.useState("")
  const listId = React.useId()
  const optionRefs = React.useRef(new Map<string, HTMLLIElement>())

  const selected = rows.find((row) => row.id === selectedId)
  const unread = rows.filter((row) => !row.read).length

  // On a phone, Back — and Archive, the list taking the mail's place — each
  // unmount the button that was pressed. The reader lands on the mail open
  // in the list, not on the top of the page; side by side the button stays,
  // and so does focus.
  const returning = React.useRef(false)
  React.useEffect(() => {
    if (!returning.current || showDetail) return
    returning.current = false
    const dropped = !document.activeElement || document.activeElement === document.body
    if (dropped && selectedId) optionRefs.current.get(selectedId)?.focus()
  }, [showDetail, selectedId])

  const change = (id: string, patch: Partial<InboxRow>) =>
    setRows((current) => current.map((row) => (row.id === id ? { ...row, ...patch } : row)))

  function select(id: string, focus = false) {
    setSelectedId(id)
    change(id, { read: true })
    if (focus) optionRefs.current.get(id)?.focus()
  }

  function onListKey(event: React.KeyboardEvent) {
    const index = rows.findIndex((row) => row.id === selectedId)
    const target =
      event.key === "ArrowDown" ? index + 1 : event.key === "ArrowUp" ? index - 1 : event.key === "Home" ? 0 : event.key === "End" ? rows.length - 1 : undefined
    if (target !== undefined) {
      event.preventDefault()
      const row = rows[Math.min(Math.max(target, 0), rows.length - 1)]
      if (row) select(row.id, true)
      return
    }
    if ((event.key === "Enter" || event.key === " ") && selectedId) {
      event.preventDefault()
      setShowDetail(true)
    }
  }

  function archive(row: InboxRow) {
    const index = rows.findIndex((candidate) => candidate.id === row.id)
    const rest = rows.filter((candidate) => candidate.id !== row.id)
    const next = rest[Math.min(index, rest.length - 1)]
    setRows(rest)
    setSelectedId(next?.id)
    if (next) change(next.id, { read: true })
    returning.current = true
    setShowDetail(false)
    setNotice(`Archived “${row.subject}”.`)
  }

  const list = (
    <div className="flex h-full min-h-0 flex-col">
      <div className="flex h-11 shrink-0 items-center justify-between gap-2 border-b px-4 text-xs text-muted-foreground">
        <span className="tabular-nums">
          Newest {rows.length} of {total}
        </span>
        <span className="tabular-nums">{unread} unread here</span>
      </div>
      {rows.length ? (
        <ul
          id={listId}
          role="listbox"
          aria-label="Inbox, newest first"
          onKeyDown={onListKey}
          className="min-h-0 flex-1 divide-y overflow-y-auto"
        >
          {rows.map((row) => {
            const isSelected = row.id === selectedId
            return (
              <li
                key={row.id}
                ref={(node) => {
                  if (node) optionRefs.current.set(row.id, node)
                  else optionRefs.current.delete(row.id)
                }}
                role="option"
                aria-selected={isSelected}
                // The row's parts are drawn as separate lines; read out, they
                // would run together, so the option says them in one sentence.
                aria-label={`${row.from.name}, ${row.read ? "" : "unread, "}${row.subject}, ${row.when}`}
                tabIndex={isSelected ? 0 : -1}
                onClick={() => {
                  select(row.id)
                  setShowDetail(true)
                }}
                className={cn(
                  "relative flex cursor-pointer gap-3 px-4 py-3 text-sm transition-colors duration-(--duration-fast) ease-(--ease-standard) hover:bg-muted/50 focus-ring-inset",
                  // Chosen: the brand's muted fill, a rail at the start and the weight — three cues, not a colour alone.
                  isSelected && "bg-brand-muted before:absolute before:inset-y-0 before:start-0 before:w-0.5 before:bg-brand hover:bg-brand-muted"
                )}
              >
                <Avatar size="sm" aria-hidden="true" className="mt-0.5">
                  <AvatarImage src={row.from.avatarUrl} alt="" />
                  <AvatarFallback>{row.from.initials}</AvatarFallback>
                </Avatar>
                <div className="flex min-w-0 flex-1 flex-col gap-0.5">
                  <div className="flex items-baseline justify-between gap-2">
                    <span className={cn("truncate", (!row.read || isSelected) && "font-medium")}>{row.from.name}</span>
                    <span className="shrink-0 text-xs text-muted-foreground tabular-nums">{row.when}</span>
                  </div>
                  <span className={cn("truncate", row.read ? "text-muted-foreground" : "font-medium text-foreground")}>
                    {row.subject}
                  </span>
                  <span className="truncate text-xs text-muted-foreground">{row.preview}</span>
                </div>
                {row.read ? null : (
                  <span aria-hidden="true" className="mt-1.5 size-2 shrink-0 rounded-full bg-foreground" />
                )}
              </li>
            )
          })}
        </ul>
      ) : (
        <p className="p-6 text-sm text-muted-foreground">Nothing left on this page of the inbox.</p>
      )}
    </div>
  )

  const detail = selected ? (
    <MailPane
      mail={selected}
      onStar={() => {
        change(selected.id, { starred: !selected.starred })
        setNotice(selected.starred ? "Star removed." : "Starred.")
      }}
      onUnread={() => {
        change(selected.id, { read: !selected.read })
        setNotice(selected.read ? `Marked “${selected.subject}” unread.` : `Marked “${selected.subject}” read.`)
      }}
      onArchive={() => archive(selected)}
    />
  ) : (
    <p className="p-6 text-sm text-muted-foreground">Choose a mail to read it here.</p>
  )

  return (
    <div className="flex flex-col gap-3">
      <div className="overflow-hidden rounded-lg bg-card ring-1 ring-border md:h-[36rem]">
        <SplitView
          list={list}
          detail={detail}
          showDetail={showDetail}
          onBack={() => {
            returning.current = true
            setShowDetail(false)
          }}
          defaultSize={38}
          minSize={28}
        />
      </div>
      <p role="status" aria-live="polite" className="text-sm text-muted-foreground">
        {notice}
      </p>
    </div>
  )
}

function MailPane({
  mail,
  onStar,
  onUnread,
  onArchive,
}: {
  mail: InboxRow
  onStar: () => void
  onUnread: () => void
  onArchive: () => void
}) {
  const subjectId = React.useId()
  return (
    <article aria-labelledby={subjectId} className="flex h-full min-h-0 flex-col">
      <div className="flex h-11 shrink-0 items-center justify-end gap-1 border-b px-2">
        <Button type="button" variant="ghost" size="icon-sm" aria-pressed={mail.starred} aria-label="Star" onClick={onStar}>
          <StarIcon aria-hidden="true" className={cn(mail.starred && "fill-current")} />
        </Button>
        <Button type="button" variant="ghost" size="sm" onClick={onUnread}>
          {mail.read ? <MailIcon aria-hidden="true" /> : <MailOpenIcon aria-hidden="true" />}
          {mail.read ? "Mark unread" : "Mark read"}
        </Button>
        <Button type="button" variant="ghost" size="sm" onClick={onArchive}>
          <ArchiveIcon aria-hidden="true" />
          Archive
        </Button>
      </div>
      <div className="flex min-h-0 flex-1 flex-col gap-5 overflow-y-auto p-4 md:p-6">
        <div className="flex flex-col gap-3">
          <h3 id={subjectId} className="text-lg font-semibold text-pretty">
            {mail.subject}
          </h3>
          <div className="flex items-start gap-3">
            <Avatar aria-hidden="true">
              <AvatarImage src={mail.from.avatarUrl} alt="" />
              <AvatarFallback>{mail.from.initials}</AvatarFallback>
            </Avatar>
            <div className="flex min-w-0 flex-1 flex-col gap-0.5 text-sm">
              <span className="font-medium">
                {mail.from.name} <span className="font-normal text-muted-foreground">&lt;{mail.from.email}&gt;</span>
              </span>
              <span className="text-xs text-muted-foreground">To {mail.to}</span>
            </div>
            <time className="shrink-0 text-xs text-muted-foreground tabular-nums">{mail.sent}</time>
          </div>
          {mail.labels.length ? (
            <div className="flex flex-wrap gap-1.5">
              {mail.labels.map((label) => (
                <Badge key={label} variant="outline" className="capitalize">
                  {label}
                </Badge>
              ))}
            </div>
          ) : null}
        </div>
        <div className="flex max-w-prose flex-col gap-3 text-sm leading-relaxed">
          {mail.paragraphs.map((paragraph, index) => (
            <p key={index}>{paragraph}</p>
          ))}
        </div>
        {mail.attachments.length ? (
          <ul aria-label="Attachments" className="flex flex-wrap gap-2">
            {mail.attachments.map((file) => (
              <li key={file.name} className="flex items-center gap-2 rounded-lg px-3 py-2 text-xs ring-1 ring-border">
                <PaperclipIcon aria-hidden="true" className="size-3.5 text-muted-foreground" />
                <span className="font-medium">{file.name}</span>
                <span className="text-muted-foreground tabular-nums">{file.size}</span>
              </li>
            ))}
          </ul>
        ) : null}
      </div>
    </article>
  )
}