State storm

let visits = 0// Live data: every page shows the same count, updated when it changes.server fn visit_count() = visitsserver fn add_visit() {    visits += 1    visits}let tabs = ["list", "grid", "form"]fn initial_items() = range(0, 12) | map((i) => { id: i, label: `Item ${i}` })component Ticker(label: str, ms: int) {    state n = 0    every(ms, () => { n += 1 })    <span.ticker>{label} <b>{n}</b></span>}component Counter(id: int, on_change) {    state n = 0    <div.counter>        <button @click={() => {            n += 1            on_change(id, n)        }}>+</button>        <b>{n}</b>    </div>}component Item(item: map, open: bool, on_toggle, on_remove) {    state clicks = 0    <li.item class={open && "open"}>        <button.link @click={() => {            clicks += 1            on_toggle(item.id)        }}>{item.label}</button>        {open && <Ticker label="open for" ms={50}/>}        <span.muted>{clicks} clicks</span>        <button.remove @click={() => { on_remove(item.id) }}>×</button>    </li>}component Where() {    let u = url()    <span.where>at {u.path}</span>}component Visits() {    state count = live(visit_count)    <div.visits>        Visits: <b>{count ?? "…"}</b>        <button @click={() => { add_visit() }}>Visit</button>    </div>}view Panel(title: str, children) =    <section.panel>        <h3>{title}</h3>        {children}    </section>component Storm() {    state items = initial_items()    state next_id = 12    state open = []    state tab = "list"    state storm = false    state changes = 0    state text = "hello"    state totals = {}    let toggle = (id) => { open = any(open, (o) => o == id) ? open | filter((o) => o != id) : open + [id] }    let remove = (id) => {        items = items | filter((it) => it.id != id)        open = open | filter((o) => o != id)    }    let counted = (id, n) => { totals = set(totals, `${id}`, n) }    let shake = () => {        let r = random_int(0, 6)        if r == 0 {            items = items + [{ id: next_id, label: `Item ${next_id}` }]            next_id += 1        }        if r == 1 && len(items) > 0 {            remove(items[random_int(0, len(items) - 1)].id)        }        if r == 2 {            items = items | sort_by((_) => random())        }        if r == 3 {            tab = tabs[random_int(0, 2)]        }        if r == 4 && len(items) > 0 {            toggle(items[random_int(0, len(items) - 1)].id)        }        if r >= 5 {            text = `change ${changes}`        }        changes += 1    }    if storm {        every(16, shake)    }    <div.storm>        <header>            <h1>StateStorm</h1>            <button.primary @click={() => { storm = !storm }}>{storm ? "Calm" : "Storm"}</button>            <button @click={() => {                storm = false                items = initial_items()                next_id = 12                open = []                tab = "list"                text = "hello"                totals = {}            }}>Reset</button>            <span.stats><b.changes>{changes}</b> changes · <b.count>{len(items)}</b> items · <b.opened>{len(open)}</b> open</span>        </header>        <aside>            {for t in tabs => <button key={t} class={t == tab && "active"} @click={() => { tab = t }}>{t}</button>}            <Where/>        </aside>        <main>            {match tab {                "list" => <ul.items>{for item in items =>                    <Item key={item.id} {item} open={any(open, (o) => o == item.id)} on_toggle={toggle} on_remove={remove}/>}</ul>                "grid" => <div.grid>{for i in range(0, 9) =>                    <Panel key={i} title={`Panel ${i}`}>                        <Ticker label="ticks" ms={40 + i * 10}/>                        <Counter id={i} on_change={counted}/>                        {i == 4 && <Visits/>}                    </Panel>}                </div>                _ => <form.form @submit={(e) => {}}>                    <label>Text <input bind:value={text}/></label>                    <p>{text} ({len(text)} characters)</p>                    <p>Totals: {len(keys(totals))} counters used</p>                </form>            }}        </main>    </div>}let style = css`* { box-sizing: border-box; }body { font: 14px/1.4 system-ui, sans-serif; margin: 0; color: #222; }.storm { display: grid; grid-template-columns: 9rem 1fr; grid-template-rows: auto 1fr; min-height: 100vh; }header { grid-column: 1 / -1; display: flex; gap: .75rem; align-items: center; padding: .6rem 1rem; border-bottom: 1px solid #e5e5e5; }header h1 { font-size: 1.1rem; margin: 0 1rem 0 0; }.stats { margin-left: auto; color: #666; font-variant-numeric: tabular-nums; }aside { display: flex; flex-direction: column; gap: .3rem; padding: 1rem; border-right: 1px solid #eee; }aside .where { margin-top: 1rem; color: #888; font-size: 12px; }main { padding: 1rem; overflow: auto; }button { font: inherit; padding: .25rem .7rem; border-radius: 6px; border: 1px solid #ccc; background: white; cursor: pointer; }button.primary { background: #222; color: white; border-color: #222; min-width: 5rem; }button.active { border-color: #222; font-weight: 600; }button.link { border: none; background: none; padding: 0; min-width: 5.5rem; text-align: left; }.items { list-style: none; padding: 0; margin: 0; columns: 2; }.item { display: flex; gap: .6rem; align-items: center; padding: .3rem .4rem; border-radius: 6px; break-inside: avoid; }.item.open { background: #eef6f0; }.item .remove { margin-left: auto; padding: 0 .45rem; }.muted, .ticker { color: #888; font-size: 12px; font-variant-numeric: tabular-nums; }.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(12rem, 1fr)); gap: .75rem; }.panel { border: 1px solid #e5e5e5; border-radius: 8px; padding: .25rem .75rem .75rem; display: flex; flex-direction: column; gap: .4rem; }.panel h3 { font-size: .9rem; margin: .5rem 0 .25rem; color: #555; }.counter { display: flex; gap: .5rem; align-items: center; }.form { display: flex; flex-direction: column; gap: .5rem; max-width: 24rem; }@media (prefers-color-scheme: dark) {  body { background: #161616; color: #ddd; }  header, aside, .panel { border-color: #2a2a2a; }  button { background: #222; color: #ddd; border-color: #444; }  button.primary { background: #ddd; color: #111; }  .item.open { background: #1d2a21; }}`route GET / =    <html>        <head>            <meta charset="utf-8"/>            <meta name="viewport" content="width=device-width, initial-scale=1"/>            <title>StateStorm</title>            <style>{style}</style>        </head>        <body><Storm/></body>    </html>