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2026-08-20 22:51:22 -03:00
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//
// main.js — extension entry point.
//
// The commands are thin: work out which file the preview is for, regenerate its
// page, and keep regenerating it while you edit. Everything about rendering
// lives in render.js and the page assets; everything about where files go lives
// in preview.js.
//
// A preview is tracked from the moment it is opened until either tab involved
// closes, at which point the generated page is thrown away again.
//
const { conf, log, warn } = require("./util.js");
const preview = require("./preview.js");
const EXPLAINED_KEY = "mermaidpreview.didExplainPreviewTab";
// Toggling a tab between source and preview may close and reopen the editor
// behind it. Cleanup waits this long and looks again, so that switching a page
// into Preview is not mistaken for closing it.
const CLEANUP_GRACE_MS = 2500;
class Controller {
constructor() {
// sourcePath -> { source, outputPath, disposables, cleanupTimer }
this.previews = new Map();
this.disposables = new CompositeDisposable();
}
// -- lifecycle ---------------------------------------------------------
activate() {
this.disposables.add(
nova.commands.register("mermaidpreview.preview", () => this.previewCommand())
);
this.disposables.add(
nova.commands.register("mermaidpreview.refresh", () => this.refreshCommand())
);
this.disposables.add(nova.commands.register("mermaidpreview.clean", () => this.cleanCommand()));
// Switching between "on save" and "as you type" changes which editor
// event we listen to, so the watchers have to be rebuilt.
this.disposables.add(
nova.config.onDidChange("mermaidpreview.updateMode", () => this.rewireWatchers())
);
// A regenerated page has to be rewritten for the new theme or width;
// the preview tab reloads itself once the file changes.
for (const key of ["mermaidpreview.theme", "mermaidpreview.contentWidth"]) {
this.disposables.add(nova.config.onDidChange(key, () => this.regenerateAll()));
}
}
deactivate() {
// Quitting Nova closes the previews too, so leave nothing behind.
for (const entry of Array.from(this.previews.values())) {
this.forget(entry, this.cleanUpOnClose());
}
this.disposables.dispose();
}
cleanUpOnClose() {
return conf("mermaidpreview.cleanUpOnClose", true) !== false;
}
// -- commands ----------------------------------------------------------
async previewCommand() {
const source = preview.describeSource(nova.workspace.activeTextEditor);
if (!source) {
nova.workspace.showErrorMessage(
"Open a Markdown (.md) or Mermaid (.mmd) file and try again. Unsaved files have no " +
"location on disk, so there is nothing to resolve their images and links against."
);
return;
}
let opened;
try {
opened = await preview.open(source);
} catch (err) {
this.report(err);
return;
}
this.watch(source, opened.outputPath, opened.editor);
this.explainPreviewTabOnce();
}
refreshCommand() {
const source = preview.describeSource(nova.workspace.activeTextEditor);
if (source && this.previews.has(source.path)) {
this.regenerate(this.previews.get(source.path).source);
return;
}
if (source) {
this.previewCommand();
return;
}
this.regenerateAll();
}
async cleanCommand() {
let directory;
try {
directory = preview.outputDirectory();
} catch (err) {
this.report(err);
return;
}
const confirmed = await new Promise((resolve) => {
nova.workspace.showActionPanel(
`Remove every page generated by Mermaid Preview, along with its assets?\n\n${directory}`,
{ buttons: ["Remove", "Cancel"] },
(index) => resolve(index === 0)
);
});
if (!confirmed) return;
try {
const removed = preview.clean();
for (const entry of Array.from(this.previews.values())) this.forget(entry, false);
nova.workspace.showInformativeMessage(
removed ? "Generated preview files removed." : "There was nothing to remove."
);
} catch (err) {
this.report(err);
}
}
// -- keeping the page current -----------------------------------------
/**
* Watches both ends of a preview: the Markdown file, so the page follows
* your edits, and the generated page, so closing it cleans up.
*/
watch(source, outputPath, previewEditor) {
const existing = this.previews.get(source.path);
if (existing) this.forget(existing, false);
const disposables = new CompositeDisposable();
const entry = { source, outputPath, disposables, cleanupTimer: null };
this.previews.set(source.path, entry);
const mode = String(conf("mermaidpreview.updateMode", "save"));
if (mode === "live") {
disposables.add(source.editor.onDidStopChanging(() => this.regenerate(source)));
} else if (mode === "save") {
disposables.add(source.editor.onDidSave(() => this.regenerate(source)));
}
// Closing the Markdown file leaves a page nothing will update again.
disposables.add(
source.editor.onDidDestroy(() => this.forget(entry, this.cleanUpOnClose()))
);
// openFile hands back the editor it opened, except when Nova restored the
// tab straight into its preview state; then look it up instead.
const pageEditor = previewEditor || preview.editorFor(outputPath);
if (pageEditor) {
disposables.add(pageEditor.onDidDestroy(() => this.scheduleCleanup(entry)));
}
}
/**
* Deletes the generated page once it has stayed closed. Nova may destroy and
* rebuild the editor when a tab flips between source and preview, so a
* destroyed editor on its own is not proof the tab is gone.
*/
scheduleCleanup(entry) {
if (!this.cleanUpOnClose()) return;
if (entry.cleanupTimer) clearTimeout(entry.cleanupTimer);
entry.cleanupTimer = setTimeout(() => {
entry.cleanupTimer = null;
if (!this.previews.has(entry.source.path)) return;
if (preview.isOpen(entry.outputPath)) return;
this.forget(entry, true);
}, CLEANUP_GRACE_MS);
}
/** Stops tracking a preview, optionally deleting the page it generated. */
forget(entry, deletePage) {
if (entry.cleanupTimer) {
clearTimeout(entry.cleanupTimer);
entry.cleanupTimer = null;
}
entry.disposables.dispose();
this.previews.delete(entry.source.path);
if (!deletePage) return;
try {
preview.discard(entry.outputPath);
} catch (err) {
warn(`Could not remove ${entry.outputPath}: ${err.message || err}`);
}
}
/** Rebuilds every watcher, used when the update mode changes. */
rewireWatchers() {
for (const entry of Array.from(this.previews.values())) {
this.watch(entry.source, entry.outputPath, null);
}
}
regenerate(source) {
try {
preview.generate(source);
} catch (err) {
// A failure here is a background one — the user asked for nothing —
// so it belongs in the console, not in an alert on every keystroke.
warn(`Could not regenerate the preview for ${source.path}: ${err.message || err}`);
}
}
regenerateAll() {
for (const entry of this.previews.values()) this.regenerate(entry.source);
}
// -- messaging ---------------------------------------------------------
/**
* The generated page opens as an editor tab. Nova remembers per file whether
* it was last shown as source or preview, so this only needs saying once.
*/
explainPreviewTabOnce() {
if (nova.config.get(EXPLAINED_KEY, "boolean")) return;
nova.config.set(EXPLAINED_KEY, true);
nova.workspace.showInformativeMessage(
"The generated page is open. Switch it to Preview once (Editor → Preview, or the preview " +
"button in the tab bar) and Nova will keep showing it that way, refreshing as you edit."
);
}
report(err) {
if (err instanceof preview.PreviewError) {
nova.workspace.showErrorMessage(err.message);
} else {
warn(err);
nova.workspace.showErrorMessage(`Could not build the preview: ${err.message || err}`);
}
}
}
const controller = new Controller();
exports.activate = function () {
controller.activate();
};
exports.deactivate = function () {
controller.deactivate();
};