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|
package main
import "strconv"
// Single self-contained page: no external assets, no build step. It is served
// from loopback to one browser window, so there is nothing to optimise for.
//
// The page never closes itself — you close the chromium window when you are
// done, and the server notices the dropped SSE stream and shuts down on its own
// after the idle timeout.
// variantCountJS keeps the page's card count tied to the Go constant, so the
// two cannot drift apart.
var variantCountJS = strconv.Itoa(variantCount)
var indexHTML = `<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>mastodon alt text</title>
<style>
:root {
--bg:#f5f5f7; --card:#ffffff; --fg:#1b1b1f; --fg2:#5f6368;
--accent:#2f6fb0; --accent-h:#245a91; --border:#dcdce0;
--good:#2e7d32; --bad:#c62828;
}
@media (prefers-color-scheme: dark) {
:root {
--bg:#161618; --card:#212124; --fg:#e8e8ea; --fg2:#a0a0a6;
--accent:#5aa3dd; --accent-h:#7bb8e8; --border:#3a3a40;
--good:#7bc47f; --bad:#e57373;
}
}
*,*::before,*::after { box-sizing:border-box; }
body { font-family:system-ui,sans-serif; background:var(--bg); color:var(--fg);
margin:0; padding:0 0 2rem 0; line-height:1.45; }
.wrap { max-width:900px; margin:0 auto; padding:0 1rem; }
header.top { position:sticky; top:0; z-index:10; background:var(--card);
border-bottom:1px solid var(--border); padding:.6rem 0; margin-bottom:1rem; }
header.top .wrap { display:flex; align-items:center; gap:.75rem; }
header.top h1 { font-size:1.05rem; margin:0; flex:1; font-weight:600; }
.status { font-size:.8rem; color:var(--fg2); white-space:nowrap; }
.status.err { color:var(--bad); }
.shot { display:block; max-width:100%; max-height:34vh; width:auto;
border:1px solid var(--border); border-radius:10px; margin:0 auto 1rem; }
/* Prompt block, directly under the image: it is a property of the picture,
and it is what the cards below are answers to, so it reads top to bottom. */
.prompt { background:var(--card); border:1px solid var(--border);
border-radius:10px; padding:.7rem .8rem; margin-bottom:1rem; }
.prompt .head { display:flex; align-items:baseline; gap:.5rem;
font-size:.76rem; color:var(--fg2); margin-bottom:.4rem; }
.prompt .head .lbl { font-weight:600; color:var(--fg); }
.prompt .head .spacer { flex:1; }
.prompt textarea { width:100%; resize:none; overflow:hidden; display:block;
font:inherit; font-size:.86rem; line-height:1.4; color:var(--fg);
background:var(--bg); border:1px solid var(--border); border-radius:7px;
padding:.45rem .55rem; }
.prompt textarea:focus { outline:2px solid var(--accent); outline-offset:-1px; }
.prompt .row { display:flex; align-items:center; gap:.5rem; margin-top:.5rem; }
.prompt .row .why { flex:1; font-size:.76rem; color:var(--fg2); }
.prompt button:disabled { background:var(--border); color:var(--fg2); cursor:not-allowed; }
/* A link, not a button: it changes the field, it does not spend a round. */
.linkbtn { background:none; border:none; padding:0; font:inherit;
font-size:.76rem; color:var(--accent); cursor:pointer; text-decoration:underline; }
.linkbtn:hover { color:var(--accent-h); }
.linkbtn[hidden] { display:none; }
.card { background:var(--card); border:1px solid var(--border); border-radius:10px;
padding:.85rem 1rem; margin:.7rem 0; cursor:pointer; position:relative;
transition:border-color .12s, transform .06s; }
.card:hover { border-color:var(--accent); }
.card:active { transform:scale(.995); }
.card[aria-disabled="true"] { cursor:default; }
.card[aria-disabled="true"]:hover { border-color:var(--border); }
.card.copied { border-color:var(--good); }
.card .text { white-space:pre-wrap; overflow-wrap:anywhere; }
.card .meta { display:flex; gap:.6rem; align-items:center;
margin-top:.55rem; font-size:.76rem; color:var(--fg2); }
.card .badge { font-weight:600; color:var(--good); }
.card .err { color:var(--bad); white-space:pre-wrap; overflow-wrap:anywhere; }
/* Skeleton lines shown until a variant arrives. */
.skel { height:.85rem; border-radius:5px; margin:.42rem 0;
background:linear-gradient(90deg,var(--border) 25%,var(--bg) 50%,var(--border) 75%);
background-size:200% 100%; animation:sweep 1.3s linear infinite; }
.skel:nth-child(2) { width:92%; }
.skel:nth-child(3) { width:74%; }
@keyframes sweep { from { background-position:200% 0; } to { background-position:-200% 0; } }
@media (prefers-reduced-motion:reduce) { .skel { animation:none; } }
.hint { color:var(--fg2); font-size:.8rem; margin-top:1.2rem; text-align:center; }
/* Refinement bar. Sticky at the bottom so it stays reachable however long
the variants are. */
.refine { position:sticky; bottom:0; background:var(--card); margin-top:1rem;
border:1px solid var(--border); border-radius:10px; padding:.7rem .8rem; }
.refine .row { display:flex; gap:.5rem; }
.refine input { flex:1; }
.refine button:disabled { background:var(--border); color:var(--fg2); cursor:not-allowed; }
.refine .why { font-size:.76rem; color:var(--fg2); margin:.45rem .1rem 0; }
.round-note { font-size:.8rem; color:var(--fg2); margin:.2rem 0 .6rem; }
.round-note b { color:var(--fg); font-weight:600; }
</style>
</head>
<body>
<header class="top"><div class="wrap">
<h1>mastodon alt text</h1>
<span class="status" id="status">reading clipboard…</span>
</div></header>
<div class="wrap">
<img class="shot" id="shot" alt="" hidden>
<div class="prompt">
<div class="head">
<span class="lbl">Prompt</span>
<span class="spacer"></span>
<button type="button" class="linkbtn" id="promptreset" hidden>reset to default</button>
</div>
<textarea id="prompt" rows="2" autocomplete="off" spellcheck="false"></textarea>
<div class="row">
<span class="why" id="promptwhy"></span>
<button id="regenbtn" disabled>Regenerate</button>
</div>
</div>
<p class="round-note" id="roundnote" hidden></p>
<div id="cards"></div>
<div class="refine">
<div class="row">
<input id="instruction" type="text" autocomplete="off"
placeholder="e.g. shorter, or: don't mention the background">
<button id="refinebtn" disabled>Refine</button>
</div>
<p class="why" id="refinewhy">Pick a variant first — refining works from the one you chose.</p>
</div>
<p class="hint">Click a variant to copy it to both selections. Close this window when you are done.</p>
</div>
<script>
(function () {
var VARIANTS = ` + variantCountJS + `;
var cards = document.getElementById('cards');
var statusEl = document.getElementById('status');
var shot = document.getElementById('shot');
var roundNote = document.getElementById('roundnote');
var instruction = document.getElementById('instruction');
var refineBtn = document.getElementById('refinebtn');
var refineWhy = document.getElementById('refinewhy');
var promptEl = document.getElementById('prompt');
var regenBtn = document.getElementById('regenbtn');
var promptWhy = document.getElementById('promptwhy');
var promptReset = document.getElementById('promptreset');
// Per-round state. currentRound guards against a stale variant from an
// earlier round arriving after a new one has started and overwriting a card
// that now belongs to someone else.
var currentRound = -1;
var texts = {};
var picked = null;
var busy = false;
// Prompt state.
//
// sentPrompt is what the cards on screen were generated from, and is the
// baseline "changed" is measured against — not the default, so that after a
// regeneration the edited prompt is the new normal and blurring the field
// again does not fire a second round.
//
// hasImage gates the button: regenerating needs the image, and until the
// clipboard has been read and converted there is nothing to caption. The
// server rejects it anyway, but a button that cannot work should look like
// it cannot work.
var sentPrompt = null;
var defaultPrompt = null;
var hasImage = false;
// Set once a fatal has been reported, only to tell the two reasons the
// prompt field is inert apart: still waiting for the clipboard, versus no
// image is coming at all.
var dead = false;
function setStatus(msg, isErr) {
statusEl.textContent = msg;
statusEl.classList.toggle('err', !!isErr);
}
// Refining needs a chosen variant to work from, and only one round may be in
// flight at a time; the server enforces both, this only keeps the button
// honest about it.
function updateRefine() {
var ready = picked !== null && !busy;
refineBtn.disabled = !ready;
if (busy) {
refineWhy.textContent = 'Generating…';
} else if (picked === null) {
refineWhy.textContent = 'Pick a variant first — refining works from the one you chose.';
} else {
refineWhy.textContent = 'Refining variant ' + (picked + 1) + '. It is already on your clipboard.';
}
}
// The textarea grows to fit its content instead of scrolling: the prompt is
// a couple of lines of prose that you edit as a whole, and a two-line window
// onto it hides the clause you are about to contradict.
function autosize() {
promptEl.style.height = 'auto';
promptEl.style.height = promptEl.scrollHeight + 'px';
}
function promptChanged() {
return promptEl.value.trim() !== (sentPrompt || '').trim();
}
function updatePrompt() {
// Enabled even when unchanged: the same prompt at this temperature gives
// three different wordings, so the button doubles as a reroll for when all
// three were bad rather than the brief being wrong.
regenBtn.disabled = busy || !hasImage || promptEl.value.trim() === '';
promptReset.hidden = defaultPrompt === null ||
promptEl.value.trim() === defaultPrompt.trim();
if (busy) {
promptWhy.textContent = 'Generating…';
} else if (dead) {
promptWhy.textContent = 'No image — nothing to caption.';
} else if (!hasImage) {
promptWhy.textContent = 'Waiting for the image.';
} else if (promptEl.value.trim() === '') {
promptWhy.textContent = 'The prompt cannot be empty.';
} else if (promptChanged()) {
promptWhy.textContent = 'Changed — regenerating starts over from the image.';
} else {
promptWhy.textContent = 'Regenerating discards any refinements.';
}
}
// doRegenerate throws the conversation away and asks again. Unlike Refine it
// needs no pick: it starts from the image, not from a variant.
function doRegenerate() {
var p = promptEl.value.trim();
if (!p || busy || !hasImage) return;
busy = true;
// Optimistic, and load-bearing: the blur handler compares against
// sentPrompt, so setting it now stops the blur that a click on this button
// causes from queueing a second, identical round.
sentPrompt = p;
updatePrompt();
updateRefine();
fetch('/regenerate', {
method: 'POST',
headers: { 'Content-Type': 'application/json' },
body: JSON.stringify({ prompt: p })
}).then(function (r) {
if (!r.ok) return r.text().then(function (t) { throw new Error(t || ('HTTP ' + r.status)); });
}).catch(function (e) {
busy = false;
updatePrompt();
updateRefine();
setStatus('regenerate failed: ' + e.message.trim(), true);
});
}
regenBtn.addEventListener('click', doRegenerate);
promptEl.addEventListener('input', function () {
autosize();
updatePrompt();
});
// Ctrl/Cmd+Enter submits; plain Enter inserts a newline, as in any textarea.
promptEl.addEventListener('keydown', function (e) {
if (e.key === 'Enter' && (e.ctrlKey || e.metaKey)) {
e.preventDefault();
doRegenerate();
}
});
// Leaving the field having changed it regenerates, which is the "changed"
// semantics of a native form control. Only on an actual change: blurring a
// field you merely clicked into must not cost three API calls.
promptEl.addEventListener('blur', function () {
if (promptChanged()) doRegenerate();
});
// blur fires before click, so a mousedown on this button would first take
// focus out of an edited textarea and regenerate — the exact round the user
// is reaching for reset to avoid. Suppressing the default mousedown keeps
// focus where it is; the click still arrives.
promptReset.addEventListener('mousedown', function (e) { e.preventDefault(); });
promptReset.addEventListener('click', function () {
if (defaultPrompt === null) return;
promptEl.value = defaultPrompt;
autosize();
updatePrompt();
// Deliberately does not regenerate: this puts the text back so you can
// edit from it, and spending a round on the way there is rarely wanted.
promptEl.focus();
});
function buildSkeletons() {
cards.innerHTML = '';
for (var i = 0; i < VARIANTS; i++) {
var c = document.createElement('div');
c.className = 'card';
c.id = 'card-' + i;
c.setAttribute('aria-disabled', 'true');
c.innerHTML = '<div class="skel"></div><div class="skel"></div><div class="skel"></div>';
c.addEventListener('click', onPick(i));
cards.appendChild(c);
}
}
// A new round replaces the cards rather than adding to them. Nothing is lost
// by that: the text a refinement started from was copied to the clipboard
// when it was picked.
function startRound(n, instr) {
currentRound = n;
texts = {};
picked = null;
buildSkeletons();
if (instr) {
roundNote.hidden = false;
roundNote.innerHTML = '';
roundNote.appendChild(document.createTextNode('Round ' + (n + 1) + ', refining with: '));
var b = document.createElement('b');
b.textContent = instr;
roundNote.appendChild(b);
} else {
roundNote.hidden = true;
}
updateRefine();
}
buildSkeletons();
updateRefine();
// The field stays empty and disabled until the server's first prompt event,
// rather than being prefilled from a copy of the default embedded here.
// Two copies of the same string drift; and a field that showed a prompt
// before the server had confirmed one could be edited into disagreeing with
// the history that was actually built.
updatePrompt();
function onPick(i) {
return function () {
if (!(i in texts)) return; // still loading, or failed
fetch('/pick', {
method: 'POST',
headers: { 'Content-Type': 'application/json' },
body: JSON.stringify({ index: i })
}).then(function (r) {
if (!r.ok) throw new Error('HTTP ' + r.status);
markCopied(i);
}).catch(function (e) {
setStatus('copy failed: ' + e.message, true);
});
};
}
function doRefine() {
var instr = instruction.value.trim();
if (!instr || picked === null || busy) return;
busy = true;
updateRefine();
fetch('/refine', {
method: 'POST',
headers: { 'Content-Type': 'application/json' },
body: JSON.stringify({ index: picked, instruction: instr })
}).then(function (r) {
if (!r.ok) return r.text().then(function (t) { throw new Error(t || ('HTTP ' + r.status)); });
instruction.value = '';
// busy stays set until the round's "done" event; the round event that
// follows is what clears the cards.
}).catch(function (e) {
busy = false;
updateRefine();
setStatus('refine failed: ' + e.message.trim(), true);
});
}
refineBtn.addEventListener('click', doRefine);
instruction.addEventListener('keydown', function (e) {
if (e.key === 'Enter') { e.preventDefault(); doRefine(); }
});
function markCopied(i) {
if (picked !== null) {
var prev = document.getElementById('card-' + picked);
if (prev) {
prev.classList.remove('copied');
var b = prev.querySelector('.badge');
if (b) b.remove();
}
}
picked = i;
var card = document.getElementById('card-' + i);
card.classList.add('copied');
var meta = card.querySelector('.meta');
if (meta && !meta.querySelector('.badge')) {
var badge = document.createElement('span');
badge.className = 'badge';
badge.textContent = 'copied \u2713';
meta.insertBefore(badge, meta.firstChild);
}
setStatus('copied to primary + clipboard');
updateRefine();
}
function renderVariant(v) {
// Ignore anything belonging to a round that is no longer on screen.
if (v.round !== currentRound) return;
var card = document.getElementById('card-' + v.index);
if (!card) return;
if (v.error) {
card.innerHTML = '<div class="err"></div>';
card.querySelector('.err').textContent = v.error;
return;
}
texts[v.index] = v.text;
card.removeAttribute('aria-disabled');
card.innerHTML = '<div class="text"></div><div class="meta"><span class="len"></span></div>';
card.querySelector('.text').textContent = v.text;
// Mastodon's alt text limit is 1500; surface it so an over-long variant is
// visible before you paste it.
var len = v.text.length;
card.querySelector('.len').textContent =
len + ' chars' + (len > 1500 ? ' \u2014 over Mastodon\u2019s 1500 limit' : '');
}
var es = new EventSource('/events');
es.addEventListener('image', function (e) {
var d = JSON.parse(e.data);
shot.src = d.url;
shot.hidden = false;
hasImage = true;
updatePrompt();
setStatus('generating ' + VARIANTS + ' variants…');
});
// The server is authoritative for the prompt: it is what actually built the
// history. Do not overwrite text being typed, though — this event also
// arrives on every reconnect, and EventSource reconnects on its own.
es.addEventListener('prompt', function (e) {
var d = JSON.parse(e.data);
defaultPrompt = d['default'];
sentPrompt = d.prompt;
if (document.activeElement !== promptEl) {
promptEl.value = d.prompt;
autosize();
}
updatePrompt();
});
es.addEventListener('round', function (e) {
var d = JSON.parse(e.data);
// Reconnecting mid-round replays this, so treat it as authoritative for
// both the round number and the fact that something is generating.
if (d.round !== currentRound) startRound(d.round, d.instruction);
busy = true;
updateRefine();
updatePrompt();
setStatus('generating ' + VARIANTS + ' variants…');
});
es.addEventListener('variant', function (e) {
renderVariant(JSON.parse(e.data));
});
es.addEventListener('done', function (e) {
var d = JSON.parse(e.data);
if (d.round !== currentRound) return;
busy = false;
updateRefine();
updatePrompt();
if (picked === null) setStatus('pick one');
});
es.addEventListener('fatal', function (e) {
setStatus(JSON.parse(e.data).error, true);
cards.innerHTML = '';
busy = false;
refineBtn.disabled = true;
refineWhy.textContent = 'Nothing to refine.';
// A fatal means there is no image, so there is nothing to regenerate
// against either; editing the prompt cannot rescue it.
hasImage = false;
dead = true;
updatePrompt();
});
// The server exits once this stream has been gone for the idle timeout, so a
// reconnect is what keeps it alive while the window is open. EventSource
// retries on its own; we only surface the gap.
es.onerror = function () {
if (es.readyState === EventSource.CLOSED) setStatus('server closed', true);
};
})();
</script>
</body>
</html>
`
|