// *************************************************************************
// * (C)opyright 2026         by Ruben Carlo Benante                       *
// *                                                                       *
// * This program is free software; you can redistribute it and/or modify  *
// *  it under the terms of the GNU General Public License as published by *
// *  the Free Software Foundation, either version 3 of the License, or    *
// *  (at your option) any later version.                                  *
// *                                                                       *
// * This program is distributed in the hope that it will be useful,       *
// *  but WITHOUT ANY WARRANTY; without even the implied warranty of       *
// *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the        *
// *  GNU General Public License for more details.                         *
// *                                                                       *
// * You should have received a copy of the GNU General Public License     *
// *  along with this program.  If not, see http://www.gnu.org/licenses/.  *
// *                                                                       *
// * Contact author at:                                                    *
// *  Ruben Carlo Benante                                                  *
// *  rcb@beco.cc                                                          *
// *************************************************************************

import { Plugin, TFile, TAbstractFile, Menu, moment } from 'obsidian';
import { extractTimeId, generateSlug, buildFilename } from './slug';

const SETTLE_MS = 5000; // rename ~5s after the H1 stops changing
const COOLDOWN_MS = 10000; // do not rename the same path again within 10s

export default class ZettelcleanPlugin extends Plugin {
	private renameTimers = new Map<string, number>();
	private lastRenamedAt = new Map<string, number>();
	private isRenameInProgress = false;

	async onload() {
		// Fires after the metadata cache reparses a note, so headings[] is fresh.
		this.registerEvent(
			this.app.metadataCache.on('changed', (file) =>
				this.scheduleSync(file),
			),
		);
		// Retrofit entry in the file-explorer right-click menu, near "Rename".
		this.registerEvent(
			this.app.workspace.on('file-menu', (menu, file) =>
				this.addTimeIdMenu(menu, file),
			),
		);
	}

	onunload() {
		for (const t of this.renameTimers.values()) window.clearTimeout(t);
		this.renameTimers.clear();
	}

	private pathFor(file: TFile, base: string): string {
		const dir =
			file.parent && file.parent.path !== '/' ? `${file.parent.path}/` : '';
		return `${dir}${base}.md`;
	}

	// Guard layer: only the actively edited zettel, honoring the 10s cooldown,
	// (re)arming the 5s settle timer on every cache change.
	private scheduleSync(file: TAbstractFile) {
		if (this.isRenameInProgress) return; // our own rename, ignore
		if (!(file instanceof TFile) || file.extension !== 'md') return;
		if (extractTimeId(file.basename) === null) return; // opt-in gate: no TIMEID
		if (this.app.workspace.getActiveFile() !== file) return; // only the edited note

		const last = this.lastRenamedAt.get(file.path);
		if (last && Date.now() - last < COOLDOWN_MS) return; // 10s cooldown

		const existing = this.renameTimers.get(file.path);
		if (existing) window.clearTimeout(existing);
		this.renameTimers.set(
			file.path,
			window.setTimeout(() => {
				this.renameTimers.delete(file.path);
				void this.syncNow(file);
			}, SETTLE_MS),
		);
	}

	// Compute the target basename, bail if unchanged, otherwise rename.
	private async syncNow(file: TFile) {
		const id = extractTimeId(file.basename);
		if (id === null) return; // prefix removed meanwhile

		const first = this.app.metadataCache.getFileCache(file)?.headings?.[0];
		const h1 = first && first.level === 1 ? first.heading : '';

		const newBase = buildFilename(id, generateSlug(h1));
		if (newBase === file.basename) return; // nothing to do

		const newPath = this.pathFor(file, newBase);
		this.isRenameInProgress = true;
		try {
			await this.app.fileManager.renameFile(file, newPath);
			this.lastRenamedAt.set(newPath, Date.now());
		} catch (e) {
			console.error('zettelclean: rename failed', e);
		} finally {
			this.isRenameInProgress = false;
		}
	}

	private addTimeIdMenu(menu: Menu, file: TAbstractFile) {
		if (!(file instanceof TFile) || file.extension !== 'md') return;
		if (extractTimeId(file.basename) !== null) return; // already a zettel
		menu.addItem((item) =>
			item
				.setTitle('Prefix timestamp to filename')
				.setIcon('clock')
				.onClick(() => void this.addTimeId(file)),
		);
	}

	// Retrofit: mint a fresh timestamp for a note that has no TIMEID yet.
	private async addTimeId(file: TFile) {
		let id = moment().format('YYYYMMDDHHmmss'); // core Unique-note format
		const first = this.app.metadataCache.getFileCache(file)?.headings?.[0];
		const h1 =
			first && first.level === 1 ? first.heading : file.basename;
		const slug = generateSlug(h1);

		let target = this.pathFor(file, buildFilename(id, slug));
		// Rare same-second + same-title collision: extend the id (up to 18 digits).
		while (this.app.vault.getAbstractFileByPath(target) && id.length < 18) {
			id += String(Math.floor(Date.now() % 10));
			target = this.pathFor(file, buildFilename(id, slug));
		}
		await this.app.fileManager.renameFile(file, target);
	}
}