use std::cell::Cell;
use std::collections::VecDeque;
use std::rc::Rc;
use std::time::Duration;
use abstracttui::app::anchored::{Completion, CompletionCandidate};
use abstracttui::prelude::*;
use abstracttui::reactive::interval;
use abstracttui::widgets::{Feed, FeedItem, FeedState};
const SCRIPT: [(&str, &str); 4] = [
(
"How does the feed stay cheap while an answer streams in?",
"# Two freezes\n\nThe stream session seals every block that can no \
longer change, and the feed typesets each sealed block **exactly \
once**:\n\n- closed blocks: parsed once, typeset once, frozen rows\n\
- the open tail: re-typeset per token, O(one block)\n\nSo a long \
answer costs the same per token at its end as at its start.",
),
(
"Show me the follow-tail idiom in code.",
"Bind one signal and the scroll does the bookkeeping:\n\n```rust\n\
let follow = cx.signal(true);\n\
Scroll::new(Feed::new(&feed).view(cx))\n\
\x20 .follow_tail(follow)\n\
\x20 .view(cx)\n```\n\nScrolling up releases it; reaching the \
bottom re-arms it; `follow.set(true)` jumps to the latest. The \
status line below renders the same signal.",
),
(
"And when the content is huge?",
"## Windowed drawing\n\nItems keep prefix sums over their heights, \
so painting binary-searches the first visible item and stops at \
the last:\n\n```rust\nlet first = prefix.partition_point(|p| *p <= top);\n\
// walk until off-screen — never the whole feed\n```\n\n> Press \
`s` and scroll around: ten thousand items, one screenful of work.",
),
(
"What about richer markdown — tables, task lists?",
"The DOC vocabulary streams too. Watch this table arrive row by \
row — it renders as a TABLE from the moment its delimiter line \
lands (the whole table is the open region until it seals):\n\n\
| stage | blocks | cost |\n|:------|-------:|-----:|\n\
| closed | 41 | frozen |\n| open tail | 1 | per token |\n\n\
And the checklist face: ~~hand-rolled parsers~~ one shared \
recipe.\n\n- [x] tables in transcripts\n- [x] strikethrough\n\
- [ ] your app here",
),
];
const CHUNK_CHARS: usize = 6;
const TURN_PAUSE_TICKS: u32 = 60;
enum Phase {
Ask,
Stream {
key: String,
chunks: VecDeque<String>,
},
Pause {
ticks: u32,
},
}
struct Script {
turn: usize,
phase: Phase,
}
impl Script {
fn new() -> Script {
Script {
turn: 0,
phase: Phase::Ask,
}
}
fn tick(&mut self, feed: &FeedState) {
match &mut self.phase {
Phase::Ask => {
let (question, answer) = SCRIPT[self.turn % SCRIPT.len()];
feed.push(
format!("q{}", self.turn),
FeedItem::markdown(format!("**you** — {question}")),
);
let key = format!("a{}", self.turn);
feed.push_stream(&key);
let chars: Vec<char> = answer.chars().collect();
let chunks = chars
.chunks(CHUNK_CHARS)
.map(|c| c.iter().collect::<String>())
.collect();
self.phase = Phase::Stream { key, chunks };
}
Phase::Stream { key, chunks } => match chunks.pop_front() {
Some(token) => {
feed.stream_append(key, &token);
}
None => {
feed.stream_finish(key);
self.turn += 1;
self.phase = Phase::Pause {
ticks: TURN_PAUSE_TICKS,
};
}
},
Phase::Pause { ticks } => {
*ticks -= 1;
if *ticks == 0 {
self.phase = Phase::Ask;
}
}
}
}
}
fn main() -> abstracttui::base::Result<()> {
if !abstracttui::term::have_tty() {
println!("transcript: needs an interactive terminal — skipping cleanly");
return Ok(());
}
if let Ok(id) = std::env::var("ABSTRACTTUI_THEME") {
set_theme_by_id(&id);
}
let mut app = App::new(Size::new(90, 28));
let quitter = app.quitter();
let overlays = app.overlays();
app.mount(move |cx| {
let t = use_theme(cx).get().tokens;
let feed = FeedState::new(cx);
let follow = cx.signal(true);
let paused = cx.signal(false);
let stressed = cx.signal(false);
let mut script = Script::new();
let stream_feed = feed.clone();
interval(cx, Duration::from_millis(25), move || {
if !paused.get_untracked() {
script.tick(&stream_feed);
}
});
let stress_feed = feed.clone();
let toggle_stress = move || {
let on = !stressed.get_untracked();
stressed.set(on);
stress_feed.clear();
if on {
for i in 0..10_000 {
stress_feed.push(
format!("h{i}"),
FeedItem::text(format!("history item {i} — windowed, never all drawn")),
);
}
}
};
let transcript = Scroll::new(Feed::new(&feed).view(cx))
.follow_tail(follow)
.view(cx);
let composer_state = TextAreaState::new(cx);
let sent = Rc::new(Cell::new(0usize));
let submit = {
let feed = feed.clone();
let state = composer_state.clone();
let quitter = quitter.clone();
move |raw: &str| {
let text = raw.trim();
if text.is_empty() {
return;
}
state.push_history(text);
state.clear();
follow.set(true); let n = sent.get();
sent.set(n + 1);
if let Some(cmd) = text.strip_prefix('/') {
let mut parts = cmd.split_whitespace();
match parts.next() {
Some("quit") => quitter.quit(),
Some("clear") => feed.clear(),
Some("theme") => {
let target = parts.next().map(str::to_string).unwrap_or_else(|| {
let themes = abstracttui::theme::list();
let now = current_theme().id;
let i = themes.iter().position(|(id, _, _)| *id == now);
let next = (i.map(|i| i + 1).unwrap_or(0)) % themes.len();
themes[next].0.to_string()
});
if !set_theme_by_id(&target) {
feed.push(
format!("c{n}"),
FeedItem::text(format!("no theme named {target:?}")),
);
}
}
Some("help") => feed.push(
format!("c{n}"),
FeedItem::markdown(
"**commands** — `/help` this list · `/theme [id]` switch or \
cycle themes · `/clear` wipe the transcript · `/quit` exit. \
`@name` mentions complete from the room list.",
),
),
other => feed.push(
format!("c{n}"),
FeedItem::text(format!(
"unknown command /{} — try /help",
other.unwrap_or_default()
)),
),
}
} else {
feed.push(
format!("u{n}"),
FeedItem::markdown(format!("**you** — {text}")),
);
}
}
};
let composer = TextArea::new()
.state(&composer_state)
.placeholder("Message — / commands · @ mentions · Enter sends")
.rows(1, 4)
.on_submit(submit)
.element(cx, &t)
.autofocus()
.build();
let composer = Completion::new()
.trigger('/', |query| {
[
("help", "list commands"),
("theme", "switch theme"),
("clear", "wipe transcript"),
("quit", "exit"),
]
.iter()
.filter(|(c, _)| c.starts_with(query))
.map(|(c, hint)| {
CompletionCandidate::new(format!("/{c}"), format!("/{c} ")).detail(*hint)
})
.collect()
})
.trigger('@', |query| {
["alice", "bob", "mnemosyne"]
.iter()
.filter(|m| m.starts_with(query))
.map(|m| CompletionCandidate::new(format!("@{m}"), format!("@{m} ")))
.collect()
})
.attach(cx, &overlays, &composer_state, composer);
let status_feed = feed.clone();
Element::new()
.style(LayoutStyle::column())
.shortcut(KeyChord::plain(Key::Char('q')), move |_| quitter.quit())
.shortcut(KeyChord::plain(Key::Char('f')), move |_| follow.set(true))
.shortcut(KeyChord::plain(Key::Char(' ')), move |_| {
paused.update(|p| *p = !*p)
})
.shortcut(KeyChord::plain(Key::Char('s')), move |_| toggle_stress())
.child(
Block::new()
.border(BorderKind::Rounded)
.title("transcript")
.fill(t.surface)
.layout(LayoutStyle::column().grow(1.0))
.child(transcript)
.element(&t)
.build(),
)
.child(composer)
.child(dyn_view(LayoutStyle::line(1), move || {
let rows = status_feed.total_rows().get();
let state = if follow.get() {
"following"
} else {
"scrolled (f to re-follow)"
};
let stream = if paused.get() { "paused" } else { "streaming" };
let stress = if stressed.get() {
" · stress 10k ON"
} else {
""
};
text(format!(
" {} items · {rows} rows · {state} · {stream}{stress}",
status_feed.len()
))
}))
.child(dyn_view(LayoutStyle::line(1), {
let caps = use_caps(cx);
move || {
let newline = if caps.get().kitty_keyboard {
"Shift+Enter newline"
} else {
"Alt+Enter / Ctrl+J newline"
};
text(format!(
" Enter send · {newline} · / commands · @ mentions · ↑↓ history · Ctrl+C quit"
))
}
}))
.build()
})?;
app.run()
}