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use std::rc::Rc;

use nsh_core::prelude::*;

#[component]
pub fn App() -> impl IntoElement {
    let titles: Rc<Vec<String>> = Rc::new((1..=10_000).map(|i| format!("Item {i}")).collect());
    virtual_list(titles.len(), move |at| {
        let titles = titles.clone();
        view()
            .p_4()
            .border_b_1()
            .border_b_color(rgb(0xeaeef2))
            .child(text(move || titles[at.index()].clone()).text_size(px(16.0)))
    })
    .estimated_item_size(px(52.0))
    .flex_1()
    .bg(white())
}

import { List, mount, Text, View } from "nsh";

const items = Array.from({ length: 10_000 }, (_, i) => ({ id: i, title: `Item ${i + 1}` }));

function App() {
  return (
    <List each={items} estimatedItemSize={52} style={{ flex: 1, backgroundColor: "#ffffff" }}>
      {(item) => (
        <View style={{ paddingHorizontal: 16, paddingVertical: 16, borderBottomWidth: 1, borderBottomColor: "#eaeef2" }}>
          <Text style={{ fontSize: 16 }}>{item().title}</Text>
        </View>
      )}
    </List>
  );
}

mount(App);

// Wrong: `title` stays the first row's title when the cell is reused.
virtual_list(count, move |at| {
    let title = titles[at.index()].clone();
    text(title)
})

// Right: the text follows the cell's current row.
virtual_list(count, move |at| {
    let titles = titles.clone();
    text(move || titles[at.index()].clone())
})

// Wrong: `title` stays the first item's title when the cell is reused.
{(item) => {
  const title = item().title;
  return <Text>{title}</Text>;
}}

// Right: the text follows the cell's current item.
{(item) => <Text>{item().title}</Text>}

let liked = signal(HashSet::<u32>::new());
let toggle = move |id: u32| {
    liked.update(|s| {
        if !s.remove(&id) {
            s.insert(id);
        }
    })
};

virtual_list(move || posts.with(Vec::len), move |at| {
    let post = computed(move || posts.with(|p| p[at.index()].clone()));
    view()
        .flex_row()
        .p_4()
        .child(text(move || post.with(|p| p.title.clone())).flex_1())
        .child(
            text(move || if liked.with(|s| s.contains(&post.with(|p| p.id))) { "♥" } else { "♡" })
                .on_press(move || toggle(post.with(|p| p.id))),
        )
})
.estimated_item_size(px(64.0))
.flex_1()

const liked = signal<Set<number>>(new Set());
const toggle = (id: number) =>
  liked.update((s) => {
    const next = new Set(s);
    next.has(id) ? next.delete(id) : next.add(id);
    return next;
  });

<List each={posts()} estimatedItemSize={64} style={{ flex: 1 }}>
  {(post) => (
    <View style={{ flexDirection: "row", padding: 16 }}>
      <Text style={{ flex: 1 }}>{post().title}</Text>
      <Text onPress={() => toggle(post().id)}>{liked().has(post().id) ? "♥" : "♡"}</Text>
    </View>
  )}
</List>

let count = photos.len();
virtual_list(count, move |at| {
    let photos = photos.clone();
    image(move || photos[at.index()].thumb.clone()).aspect_square().rounded(px(8.0))
})
.columns(3)
.estimated_item_size(px(120.0))
.content_padding(px(12.0))
.row_gap(px(8.0))
.column_gap(px(8.0))
.flex_1()

<List
  each={photos}
  numColumns={3}
  estimatedItemSize={120}
  style={{ flex: 1 }}
  contentStyle={{ padding: 12, gap: 8 }}
>
  {(photo) => <Image src={photo().thumb} style={{ aspectRatio: 1, borderRadius: 8 }} />}
</List>

#[derive(Clone, PartialEq)]
enum Row {
    Header(String),
    Name(String),
}

let mut rows = Vec::new();
let mut headers = Vec::new();
for (letter, names) in groups {
    headers.push(rows.len());
    rows.push(Row::Header(letter));
    rows.extend(names.into_iter().map(Row::Name));
}
let count = rows.len();
let rows = Rc::new(rows);

virtual_list(count, move |at| {
    let rows = rows.clone();
    let row = computed(move || rows[at.index()].clone());
    let is_header = computed(move || matches!(row.get(), Row::Header(_)));
    let label = move || match row.get() {
        Row::Header(s) | Row::Name(s) => s,
    };
    when(is_header, move || {
        text(label).p(px(6.0)).bg(rgb(0xeaeef2)).font_weight(FontWeight::BOLD)
    })
    .otherwise(move || text(label).p_3())
})
.sticky_header_indices(headers)
.estimated_item_size(px(44.0))
.flex_1()

type Row = { header: string } | { name: string };

const rows: Row[] = [];
const headers: number[] = [];
for (const [letter, names] of groups) {
  headers.push(rows.length);
  rows.push({ header: letter });
  for (const name of names) rows.push({ name });
}

<List each={rows} stickyHeaderIndices={headers} estimatedItemSize={44} style={{ flex: 1 }}>
  {(row) => (
    <If
      when={"header" in row()}
      else={<Text style={{ padding: 12 }}>{(row() as { name: string }).name}</Text>}
    >
      <Text style={{ padding: 6, backgroundColor: "#eaeef2", fontWeight: "700" }}>{(row() as { header: string }).header}</Text>
    </If>
  )}
</List>

let offset = animated_value(0.0);
let hidden = offset.diff_clamp(0.0, 56.0);
let shown = hidden.mul(-1.0).add(56.0);

view().flex_1().overflow_hidden().child(
    virtual_list(rows.len(), row)
        .scroll_value(&offset)
        .sticky_header_indices(headers)
        .bind_sticky_header_offset(&shown),
).child(view().absolute().top_0().left_0().right_0().h(px(56.0)).bind_translate_y(&hidden.mul(-1.0)))

const scroll = createAnimatedValue(0);
const hidden = scroll.diffClamp(0, 56);
const shown = hidden.mul(-1).add(56);

<View style={{ flex: 1, overflow: "hidden" }}>
  <List each={rows} scrollValue={scroll} stickyHeaderIndices={headers} stickyHeaderOffset={shown}>…</List>
  <View style={{ position: "absolute", top: 0, left: 0, right: 0, height: 56, translate: [0, hidden.mul(-1)] }}>…</View>
</View>

#[derive(Clone, PartialEq)]
struct Message {
    id: u32,
    text: String,
    mine: bool,
}

pub fn chat() -> impl IntoElement {
    let next = stored(0_u32);
    let message = move |text: String, mine: bool| Message {
        id: next.with(|n| {
            *n += 1;
            *n
        }),
        text,
        mine,
    };
    // Newest first.
    let messages = signal(
        (0..30)
            .map(|i| message(format!("Message {}", 30 - i), i % 3 == 0))
            .collect::<Vec<_>>(),
    );
    let draft = signal(String::new());
    let send = move || {
        let text = draft.get_untracked();
        if text.trim().is_empty() {
            return;
        }
        let sent = message(text, true);
        messages.update(|m| m.insert(0, sent));
        draft.set(String::new());
    };
    let load_older = move || {
        let older: Vec<_> = (0..20).map(|i| message(format!("Older {i}"), false)).collect();
        messages.update(|m| m.extend(older));
    };
    let list = virtual_list(
        move || messages.with(Vec::len),
        move |at| {
            let mine = computed(move || messages.with(|m| m[at.index()].mine));
            view()
                .style_when(mine, |s| s.self_end().bg(rgb(0x0969da)))
                .style_when(move || !mine.get(), |s| s.self_start().bg(rgb(0xeaeef2)))
                .max_w(relative(0.75))
                .px_3()
                .py_2()
                .rounded(px(14.0))
                .child(
                    text(move || messages.with(|m| m[at.index()].text.clone()))
                        .text_color(move || if mine.get() { rgb(0xffffff) } else { rgb(0x1f2328) }),
                )
        },
    )
    .keys(move || messages.with(|m| m.iter().map(|m| m.id).collect::<Vec<_>>()))
    .inverted()
    .estimated_item_size(px(44.0))
    .content_padding(px(12.0))
    .row_gap(px(6.0))
    .keyboard_dismiss_mode(KeyboardDismissMode::Interactive)
    .on_load_more(load_older)
    .load_more_threshold(0.5)
    .flex_1();
    view()
        .flex_1()
        .pb_keyboard()
        .child(list)
        .child(
            view().flex_row().gap_2().p_2().child(
                input()
                    .value(move || draft.get())
                    .on_change(move |text: &str| draft.set(text.to_owned()))
                    .on_submit(move |_: &str| send())
                    .multiline(true)
                    .submit_behavior(SubmitBehavior::Submit)
                    .return_key_type(ReturnKeyType::Send)
                    .placeholder("Message")
                    .flex_1()
                    .max_h(px(120.0))
                    .border_1()
                    .border_color(rgb(0xd0d7de))
                    .rounded(px(18.0))
                    .px_3()
                    .py_2(),
            ),
        )
}

import { List, mount, signal, Text, View } from "nsh";
import { Input } from "nsh/base";

type Message = { id: number; text: string; mine: boolean };

function Chat() {
  let next = 0;
  const message = (text: string, mine: boolean): Message => ({ id: next++, text, mine });
  const messages = signal(Array.from({ length: 30 }, (_, i) => message(`Message ${30 - i}`, i % 3 === 0)));
  const draft = signal("");
  const send = () => {
    if (!draft().trim()) return;
    messages.update((m) => [message(draft(), true), ...m]); // newest first
    draft.set("");
  };
  const loadOlder = () => messages.update((m) => [...m, ...Array.from({ length: 20 }, (_, i) => message(`Older ${i}`, false))]);
  return (
    <View style={{ flex: 1, paddingBottom: "env(keyboard-inset-height)" }}>
      <List
        each={messages()}
        inverted
        estimatedItemSize={44}
        style={{ flex: 1 }}
        contentStyle={{ padding: 12, gap: 6 }}
        keyboardDismissMode="interactive"
        onLoadMore={loadOlder}
        loadMoreThreshold={0.5}
      >
        {(m) => (
          <View
            style={{
              alignSelf: m().mine ? "flex-end" : "flex-start",
              maxWidth: "75%",
              paddingHorizontal: 12,
              paddingVertical: 8,
              borderRadius: 14,
              backgroundColor: m().mine ? "#0969da" : "#eaeef2",
            }}
          >
            <Text style={{ color: m().mine ? "#ffffff" : "#1f2328" }}>{m().text}</Text>
          </View>
        )}
      </List>
      <View style={{ flexDirection: "row", gap: 8, padding: 8 }}>
        <Input
          value={draft()}
          onChange={({ value }) => draft.set(value)}
          onSubmit={send}
          multiline
          submitBehavior="submit"
          returnKeyType="send"
          placeholder="Message"
          style={{ flex: 1, maxHeight: 120, borderWidth: 1, borderColor: "#d0d7de", borderRadius: 18, paddingHorizontal: 12, paddingVertical: 8 }}
        />
      </View>
    </View>
  );
}

mount(Chat);

virtual_list(move || messages.with(Vec::len), move |at| bubble(messages, at))
    .keys(move || messages.with(|m| m.iter().map(|m| m.id).collect::<Vec<_>>()))
    .follow_end(px(40.0))
    .flex_1()

<List each={messages()} keyExtractor={(m) => m.id} maintainVisibleContentPosition={{ autoscrollToBottomThreshold: 40 }} style={{ flex: 1 }}>
  {(m) => <Bubble message={m()} />}
</List>

let count = cards.len();
virtual_list(count, move |at| {
    let cards = cards.clone();
    view()
        .w(px(220.0))
        .h(px(140.0))
        .rounded(px(14.0))
        .bg(move || cards[at.index()].color)
})
.horizontal()
.estimated_item_size(px(232.0))
.snap_interval(px(232.0))
.deceleration(0.99)
.scrollbar(false)
.content_padding_x(px(16.0))
.column_gap(px(12.0))
.h(px(140.0))

<List
  each={cards}
  horizontal
  estimatedItemSize={232}
  snapToInterval={232}
  decelerationRate="fast"
  scrollbar={false}
  style={{ height: 140 }}
  contentStyle={{ paddingHorizontal: 16, gap: 12 }}
>
  {(card) => <View style={{ width: 220, height: 140, borderRadius: 14, backgroundColor: card().color }} />}
</List>

scroll()
    .flex_1()
    .child(header())
    .child(
        virtual_list(count, row)
            .viewport(ListViewport::Parent)
            .estimated_item_size(px(56.0))
            .row_gap(px(6.0)),
    )
    .child(footer())

<Scroll style={{ flex: 1 }}>
  <Header />
  <List viewport="parent" each={items} estimatedItemSize={56} contentStyle={{ gap: 6 }}>
    {(item) => <Row item={item()} />}
  </List>
  <Footer />
</Scroll>

let posts = signal(Vec::<Post>::new());
let page = stored(0_u32);
let loading = stored(false);

let load_more = move || {
    if loading.replace(true) {
        return;
    }
    let next = page.with(|p| {
        *p += 1;
        *p
    });
    spawn(async move {
        if let Ok(response) = fetch(format!("https://api.example.com/posts?page={next}")).await {
            let more = parse_posts(&response.text());
            posts.update(|p| p.extend(more));
        }
        loading.replace(false);
    });
};
load_more();

virtual_list(move || posts.with(Vec::len), move |at| post_row(posts, at))
    .estimated_item_size(px(72.0))
    .on_load_more(load_more)
    .load_more_threshold(0.5)
    .footer(text("Loading…").p_4().text_center().text_color(rgb(0x8c959f)))
    .flex_1()

const posts = signal<Post[]>([]);
let loading = false;
let page = 0;

const loadMore = async () => {
  if (loading) return;
  loading = true;
  try {
    const next: Post[] = await (await fetch(`https://api.example.com/posts?page=${++page}`)).json();
    posts.set([...posts(), ...next]);
  } finally {
    loading = false;
  }
};
loadMore();

<List
  each={posts()}
  estimatedItemSize={72}
  style={{ flex: 1 }}
  onLoadMore={loadMore}
  loadMoreThreshold={0.5}
  footer={<Text style={{ padding: 16, textAlign: "center", color: "#8c959f" }}>Loading…</Text>}
>
  {(post) => <PostRow post={post()} />}
</List>

let messages = signal(page_around(target)); // newest first, ending at an old message
let loading = stored(false);

let load_newer = move |_: &()| {
    if loading.replace(true) {
        return;
    }
    let newest = messages.with(|m| m[0].id);
    spawn(async move {
        if let Ok(response) = fetch(format!("https://api.example.com/messages?after={newest}")).await {
            let newer = parse_messages(&response.text());
            messages.update(|m| {
                m.splice(0..0, newer);
            });
        }
        loading.replace(false);
    });
};

virtual_list(move || messages.with(Vec::len), move |at| message_row(messages, at))
    .inverted(true)
    .on_load_more(load_older)
    .on_load_more_at_start(load_newer)
    .load_more_at_start_threshold(0.5)
    .flex_1()

const messages = signal<Message[]>(pageAround(target)); // newest first, ending at an old message
let loading = false;

const loadNewer = async () => {
  if (loading) return;
  loading = true;
  try {
    const newest = messages()[0].id;
    const newer: Message[] = await (await fetch(`https://api.example.com/messages?after=${newest}`)).json();
    messages.set([...newer, ...messages()]);
  } finally {
    loading = false;
  }
};

<List
  each={messages()}
  inverted
  style={{ flex: 1 }}
  onLoadMore={loadOlder}
  onLoadMoreAtStart={loadNewer}
  loadMoreAtStartThreshold={0.5}
>
  {(message) => <Bubble message={message()} />}
</List>

let playing = signal(None::<usize>);

virtual_list(count, move |at| video_card(videos.clone(), at))
    .estimated_item_size(px(300.0))
    .viewability(Viewability {
        item_visible_threshold: Some(Percentage(0.6)),
        ..Viewability::default()
    })
    .minimum_view_time(Duration::from_millis(250))
    .on_viewable_items_change(move |rows: &ViewableItems| {
        playing.set(rows.viewable.map(|(first, _)| first))
    })
    .flex_1()

<List
  each={videos}
  estimatedItemSize={300}
  style={{ flex: 1 }}
  keyExtractor={(v) => v.slug}
  viewabilityConfig={{ itemVisibleThreshold: 0.6, minimumViewTime: 250 }}
  onViewableItemsChange={({ viewableItems }) => playing.set(viewableItems[0]?.key ?? null)}
>
  {(v) => <VideoCard video={v()} />}
</List>

let list = element_ref();

virtual_list(count, row).estimated_item_size(px(48.0)).flex_1().element_ref(&list)

list.scroll_to_index(120, percentage(0.5), px(0.0), true);

import { List, type ListRef } from "nsh";

let list!: ListRef;

<List ref={list} each={items} estimatedItemSize={48} style={{ flex: 1 }}>…</List>

list.scrollToIndex({ index: 120, viewPosition: 0.5 });

use std::rc::Rc;

use nsh_core::{element::palette::NEUTRAL, prelude::*};

pub struct Setting {
    pub id: &'static str,
    pub label: &'static str,
}

pub fn settings_list(settings: Rc<Vec<Setting>>, on_select: impl Fn(&Setting) + 'static) -> impl IntoElement {
    let surface = AdaptiveColor::new(white(), NEUTRAL.shade(900));
    let on_select = Rc::new(on_select);
    let count = settings.len();
    view().flex_1().bg(AdaptiveColor::new(NEUTRAL.shade(100), NEUTRAL.shade(950))).child(
        virtual_list(count, move |at| {
            let (pressed, shown, on_select) = (settings.clone(), settings.clone(), on_select.clone());
            view()
                .on_press(move || on_select(&pressed[at.index()]))
                .role(AccessibilityRole::Button)
                .h_12()
                .justify_center()
                .bg(surface)
                .px_4()
                .active(|s| s.bg(NEUTRAL.shade(200)))
                .rounded_t(move || px(if at.is_first() { 12.0 } else { 0.0 }))
                .rounded_b(move || px(if at.is_last() { 12.0 } else { 0.0 }))
                .child(text(move || shown[at.index()].label))
        })
        .estimated_item_size(px(48.0))
        .content_padding(px(16.0))
        .separator(move || {
            view()
                .bg(surface)
                .child(view().ml_4().h(px(1.0)).bg(AdaptiveColor::new(NEUTRAL.shade(200), NEUTRAL.shade(800))))
        })
        .flex_1(),
    )
}

import { List, Text, View } from "nsh";

type Setting = { id: string; label: string };

function SettingsList(props: { each: Setting[]; onSelect: (s: Setting) => void }) {
  return (
    <View class="flex-1 bg-neutral-100 dark:bg-neutral-950">
      <List
        each={props.each}
        estimatedItemSize={48}
        style={{ flex: 1 }}
        contentStyle={{ padding: 16 }}
        separator={() => (
          <View class="bg-white dark:bg-neutral-900">
            <View class="ml-4 h-px bg-neutral-200 dark:bg-neutral-800" />
          </View>
        )}
      >
        {(s, i) => (
          <View
            onPress={() => props.onSelect(s())}
            role="button"
            class="h-12 justify-center bg-white px-4 active:bg-neutral-200 dark:bg-neutral-900"
            classList={{ "rounded-t-xl": i() === 0, "rounded-b-xl": i() === props.each.length - 1 }}
          >
            <Text>{s().label}</Text>
          </View>
        )}
      </List>
    </View>
  );
}