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Skald-Circle/web/components/shared/file-viewer-base.js
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2026-07-10 15:02:09 +01:00

430 lines
17 KiB
JavaScript

import { html, nothing } from 'lit';
import { unsafeHTML } from 'lit/directives/unsafe-html.js';
import { LightElement, renderMarkdown } from '../../lib/base.js';
import { fileWatcher } from '../../lib/file-watcher.js';
/**
* Shared file-viewer engine. Holds all of the fetch / kind-detection /
* markdown-asset-rewriting / LaTeX-compile / live-watch logic plus `_renderBody`,
* driven purely by two methods: `_show(path)` and `_hide()`. It carries no
* navigation or page chrome of its own — subclasses (desktop `<file-viewer-page>`
* and mobile `<mobile-file-viewer-page>`) wire visibility/path to those methods
* and provide their own `render()` header.
*/
const IMG_EXTS = ['png', 'jpg', 'jpeg', 'gif', 'webp', 'bmp', 'ico', 'avif'];
const LATEX_EXTS = ['tex', 'latex'];
const TEXT_EXTS = [
'txt', 'md', 'markdown', 'rs', 'js', 'mjs', 'cjs', 'ts', 'tsx', 'jsx',
'py', 'json', 'yml', 'yaml', 'toml', 'sh', 'bash', 'zsh', 'fish',
'css', 'scss', 'less',
'sql', 'go', 'java', 'c', 'h', 'cpp', 'hpp', 'cc', 'kt', 'scala',
'lua', 'pl', 'php', 'rb', 'swift', 'dart',
'xml', 'csv', 'tsv', 'log', 'env', 'ini', 'cfg', 'conf',
'gitignore', 'dockerignore', 'editorconfig',
'vue', 'svelte', 'astro',
// LaTeX is also kept here as the fallback when compilation fails — kindFor
// still routes it to 'latex' so the viewer knows to attempt a compile first.
'tex', 'latex',
];
export function extOf(path) {
if (!path) return '';
const dot = path.lastIndexOf('.');
if (dot < 0) return '';
// Reject dots that are inside a directory segment, not the file extension.
if (path.indexOf('/', dot + 1) >= 0) return '';
return path.slice(dot + 1).toLowerCase();
}
export function kindFor(path) {
const ext = extOf(path);
// SVG is excluded from IMG_EXTS on purpose: rendered in a sandboxed iframe
// (not <img>), which both scales viewBox-only SVGs to fill the viewport and
// isolates any embedded <script> from the host page.
if (ext === 'svg') return 'svg';
if (IMG_EXTS.includes(ext)) return 'image';
if (ext === 'pdf') return 'pdf';
// HTML is rendered live in a script-enabled but origin-isolated iframe
// (srcdoc + sandbox="allow-scripts", no allow-same-origin) — see _renderBody.
if (ext === 'html' || ext === 'htm') return 'html';
if (LATEX_EXTS.includes(ext)) return 'latex';
if (TEXT_EXTS.includes(ext)) return 'text';
return 'binary';
}
/** Directory portion of a path: `docs/guide.md` → `docs`, `guide.md` → ``. */
function dirOf(path) {
const i = path.lastIndexOf('/');
return i < 0 ? '' : path.slice(0, i);
}
/** Lexically resolve `.`/`..` segments, preserving a leading slash for absolute paths. */
function normalizePath(p) {
const abs = p.startsWith('/');
const out = [];
for (const seg of p.split('/')) {
if (seg === '' || seg === '.') continue;
if (seg === '..') { out.pop(); continue; }
out.push(seg);
}
return (abs ? '/' : '') + out.join('/');
}
/**
* Resolve an asset reference found inside a markdown file. External URLs, data
* URIs, protocol-relative and root-relative paths are left untouched; a path
* relative to the markdown file's directory is routed through `/api/file` so it
* loads from disk instead of resolving against the SPA origin.
*/
function resolveAssetSrc(src, baseDir) {
if (!src || /^([a-z][a-z0-9+.-]*:|\/\/|#|\/)/i.test(src)) return src;
const joined = baseDir ? `${baseDir}/${src}` : src;
return `/api/file?path=${encodeURIComponent(normalizePath(joined))}`;
}
/**
* Rewrite relative `<img>` sources in rendered markdown HTML so they resolve
* against the markdown file's location on disk (via `/api/file`). Parsed in an
* inert <template> so the original (broken) URLs never trigger a fetch.
*/
function rewriteMarkdownAssets(htmlStr, baseDir) {
const tpl = document.createElement('template');
tpl.innerHTML = htmlStr;
let changed = false;
for (const img of tpl.content.querySelectorAll('img[src]')) {
const src = img.getAttribute('src');
const resolved = resolveAssetSrc(src, baseDir);
if (resolved !== src) { img.setAttribute('src', resolved); changed = true; }
}
return changed ? tpl.innerHTML : htmlStr;
}
/**
* Distil a raw latexmk / xelatex log into its actionable error block.
*
* The 422 body carries the *full* log. Under `-file-line-error` the meaningful
* `path:line: message` errors (and `! TeX error` lines) sit deep in the log —
* the opening lines are only the engine banner and package preamble. Slicing
* the first N characters therefore hid the real error; instead we extract the
* error lines plus a few trailing context lines (LaTeX echoes the offending
* source line right after) so the user can read it — or paste it straight into
* an agent. Falls back to the log tail when no error line is recognised.
*/
function formatLatexError(log) {
if (!log) return '';
const lines = log.split('\n');
const blocks = [];
for (let i = 0; i < lines.length; i++) {
if (/:\d+: /.test(lines[i]) || lines[i].startsWith('! ')) {
blocks.push(lines.slice(i, i + 4).join('\n').trimEnd());
}
}
const excerpt = blocks.join('\n\n').trim();
if (excerpt) return excerpt;
return (log.length > 4000 ? log.slice(-4000) : log).trim();
}
export class FileViewerBase extends LightElement {
static properties = {
_path: { state: true },
_kind: { state: true },
_content: { state: true },
_blobUrl: { state: true },
_loading: { state: true },
_error: { state: true },
_compileError: { state: true },
_htmlMode: { state: true },
};
constructor() {
super();
this._path = null;
this._kind = null;
this._content = '';
this._blobUrl = null;
this._loading = false;
this._error = null;
this._compileError = null;
this._htmlMode = 'preview'; // HTML view: 'preview' (live iframe) | 'source'
this._watchPath = null; // path currently being watched (async-verified)
this._watchUnsub = null; // unsubscribe function returned by fileWatcher
this._reloadTimer = null; // debounce timer for change-triggered reloads
}
disconnectedCallback() {
super.disconnectedCallback();
this._teardownWatch();
if (this._reloadTimer) clearTimeout(this._reloadTimer);
this._revokeBlobUrl();
}
// ── Drivers used by subclasses ──────────────────────────────────────────────
/** Show `path`: (re)subscribe the watcher and load it. No-op if unchanged. */
_show(path) {
if (!path) return;
if (path === this._path && !this._error) return; // already loaded
this._setupWatch(path);
this._load(path);
}
/** Hide: drop the content and release the watcher. */
_hide() {
this._reset();
this._teardownWatch();
}
/**
* Download the current file. LaTeX sources always download the compiled PDF
* (`compile-latex=true`); every kind is served with `force_download=true` so
* the server sets `Content-Disposition: attachment` and the browser saves it
* (with the server-supplied name) instead of rendering inline.
*/
_download() {
const path = this._path;
if (!path) return;
const params = new URLSearchParams({ path });
if (this._kind === 'latex') params.set('compile-latex', 'true');
params.set('force_download', 'true');
const a = document.createElement('a');
a.href = `/api/file?${params.toString()}`;
a.download = ''; // server Content-Disposition supplies the name
document.body.appendChild(a);
a.click();
a.remove();
}
_revokeBlobUrl() {
if (this._blobUrl) {
URL.revokeObjectURL(this._blobUrl);
this._blobUrl = null;
}
}
_reset() {
this._path = null;
this._kind = null;
this._content = '';
this._error = null;
this._compileError = null;
this._htmlMode = 'preview';
this._revokeBlobUrl();
}
async _load(path, silent = false) {
if (!silent) {
this._path = path;
this._kind = kindFor(path);
this._content = '';
this._error = null;
this._compileError = null;
this._revokeBlobUrl();
this._loading = true;
} else {
// Silent reload (file changed externally): keep showing the old content
// until the new fetch lands; only update visible state on success.
this._error = null;
}
try {
const url = `/api/file?path=${encodeURIComponent(path)}`;
if (this._kind === 'image' || this._kind === 'pdf' || this._kind === 'svg') {
const res = await fetch(url);
if (!res.ok) throw new Error(`HTTP ${res.status}`);
const blob = await res.blob();
// Swap URLs only after the new blob is ready so the preview never flickers.
const oldUrl = this._blobUrl;
this._blobUrl = URL.createObjectURL(blob);
if (oldUrl) URL.revokeObjectURL(oldUrl);
} else if (this._kind === 'latex') {
await this._loadLatex(path);
} else if (this._kind === 'text' || this._kind === 'html') {
const res = await fetch(url);
if (!res.ok) throw new Error(`HTTP ${res.status}`);
this._content = await res.text();
}
// binary: nothing to fetch
} catch (e) {
this._error = e.message || String(e);
} finally {
if (!silent) this._loading = false;
}
}
/**
* Load a `.tex` / `.latex` file. Tries to compile to PDF server-side first;
* on any non-OK response (422 compilation error, 501 no latexmk, etc.) it
* falls back to showing the raw source as plain text, preserving the error
* message so the user can see why the compile failed.
*/
async _loadLatex(path) {
const compileUrl = `/api/file?path=${encodeURIComponent(path)}&compile-latex=true`;
try {
const res = await fetch(compileUrl);
if (res.ok) {
const blob = await res.blob();
const oldUrl = this._blobUrl;
this._blobUrl = URL.createObjectURL(blob);
if (oldUrl) URL.revokeObjectURL(oldUrl);
this._content = '';
this._compileError = null;
return;
}
// The 422 body is the full latexmk log. Extract the actionable error
// block (see formatLatexError) instead of slicing from the top, which
// under -file-line-error only shows the preamble and hides the real error.
let detail = '';
try { detail = formatLatexError(await res.text()); } catch { /* ignore */ }
this._compileError = detail || `HTTP ${res.status}`;
} catch (e) {
this._compileError = e.message || String(e);
}
// Fallback: fetch the raw .tex source.
this._revokeBlobUrl();
const res = await fetch(`/api/file?path=${encodeURIComponent(path)}`);
if (!res.ok) throw new Error(`HTTP ${res.status}`);
this._content = await res.text();
}
// ── File watcher ────────────────────────────────────────────────────────────
_setupWatch(path) {
this._teardownWatch();
if (!path) return;
this._watchPath = path;
fileWatcher.watch(path, () => this._onFileChanged())
.then(unsub => {
// Race: if the path changed or the page closed while awaiting, release
// the subscription immediately so the OS watcher is torn down.
if (this._watchPath !== path) {
try { unsub(); } catch { /* ignore */ }
return;
}
this._watchUnsub = unsub;
})
.catch(() => { /* WS error; client auto-reconnects and re-subscribes */ });
}
_teardownWatch() {
if (this._reloadTimer) {
clearTimeout(this._reloadTimer);
this._reloadTimer = null;
}
if (this._watchUnsub) {
try { this._watchUnsub(); } catch { /* ignore */ }
this._watchUnsub = null;
}
this._watchPath = null;
}
_onFileChanged() {
// Debounce: collapse bursts of FS events into a single reload. `_watchPath`
// is cleared by `_teardownWatch` (called on hide/path-change), so a queued
// change never reloads a file the viewer has already navigated away from.
if (this._reloadTimer) return;
this._reloadTimer = setTimeout(() => {
this._reloadTimer = null;
const path = this._watchPath;
if (path) this._load(path, true);
}, 300);
}
// ── HTML preview/source toggle ──────────────────────────────────────────────
_toggleHtmlMode() {
this._htmlMode = this._htmlMode === 'preview' ? 'source' : 'preview';
}
/**
* Header button that flips an HTML file between the live preview and its raw
* source. Returns `nothing` for every other kind, so subclasses can drop it
* unconditionally into their header. `btnClass` carries the chrome-specific
* button styling (desktop vs mobile use different classes).
*/
_renderModeToggle(btnClass) {
if (this._kind !== 'html') return nothing;
const showingSource = this._htmlMode === 'source';
return html`<button
class=${btnClass}
title=${showingSource ? 'Show preview' : 'Show source'}
@click=${() => this._toggleHtmlMode()}>
<i class="bi ${showingSource ? 'bi-eye' : 'bi-code-slash'}"></i>
</button>`;
}
// ── Body rendering (shared by both chromes) ─────────────────────────────────
_renderBody() {
// Spinner while loading, and also in the pre-load window: the mobile viewer
// is prop-driven, so Lit runs render() (visible just flipped true) before
// `updated()` kicks off `_show()` — at that point no kind/content exists yet.
if (this._loading || (!this._kind && !this._error)) {
return html`<div class="fv-state"><span class="spinner-border"></span></div>`;
}
if (this._error) {
return html`<div class="fv-state text-danger">
<i class="bi bi-exclamation-triangle fs-3 d-block mb-2"></i>${this._error}
</div>`;
}
if (this._kind === 'image' && this._blobUrl) {
return html`<div class="fv-image-wrap"><img src=${this._blobUrl} alt=${this._path} class="fv-image" /></div>`;
}
if (this._kind === 'pdf' && this._blobUrl) {
return html`<iframe class="fv-pdf" src=${this._blobUrl} title=${this._path}></iframe>`;
}
if (this._kind === 'latex' && this._blobUrl) {
// Successfully compiled server-side — render the resulting PDF the same
// way a native .pdf would be rendered.
return html`<iframe class="fv-pdf" src=${this._blobUrl} title=${this._path}></iframe>`;
}
if (this._kind === 'svg' && this._blobUrl) {
// `allow-same-origin` (and nothing else) is required so the iframe can load
// the blob: URL — those are only readable from their creating origin. With
// `allow-scripts` absent, any <script> inside the SVG still cannot execute,
// so this stays an isolated, script-free render.
return html`<div class="fv-image-wrap">
<iframe class="fv-svg" sandbox="allow-same-origin" src=${this._blobUrl} title=${this._path}></iframe>
</div>`;
}
if (this._kind === 'binary') {
return html`<div class="fv-state text-muted">
<i class="bi bi-file-earmark-binary fs-3 d-block mb-2"></i>
Preview not available for this file type.
</div>`;
}
if (this._kind === 'html') {
if (this._htmlMode === 'source') {
return html`<pre class="fv-code"><code>${this._content}</code></pre>`;
}
// Live render. `srcdoc` (not a blob: src) gives the frame a unique opaque
// origin, so `allow-scripts` can run the page's JS while it stays fully
// isolated from the app origin — no `allow-same-origin`, so it cannot read
// cookies/localStorage or reach `/api/*`. Never add allow-same-origin here:
// combined with allow-scripts it lets the frame remove its own sandbox.
return html`<iframe
class="fv-html"
sandbox="allow-scripts allow-forms allow-modals allow-popups"
srcdoc=${this._content}
title=${this._path}></iframe>`;
}
const ext = extOf(this._path);
if (ext === 'md' || ext === 'markdown') {
const rendered = rewriteMarkdownAssets(renderMarkdown(this._content), dirOf(this._path || ''));
return html`<div class="fv-md">${unsafeHTML(rendered)}</div>`;
}
if (this._kind === 'latex') {
// Compile failed — show why, then fall back to the source.
return html`
${this._compileError
? html`<details class="fv-compile-error">
<summary><i class="bi bi-exclamation-triangle text-warning"></i>&nbsp;LaTeX compilation failed — showing source instead</summary>
<pre>${this._compileError}</pre>
</details>`
: nothing}
<pre class="fv-code"><code>${this._content}</code></pre>
`;
}
return html`<pre class="fv-code"><code>${this._content}</code></pre>`;
}
}