import {
	BrowserFileIOAdapter,
	BrowserSystemAdapter,
	executeCode,
	RuntimeError,
	VirtualFileSystem,
} from 'numbl';
import type { RunRequest, WorkerResponse } from './protocol';

// The numbl execution worker. executeCode is synchronous, so it must run off
// the main thread; this mirrors numbl's own (unpublished) numbl-worker.ts in
// its non-persistent mode: each run gets a fresh VFS seeded with the whole
// project, the script's directory becomes the cwd / first search path, and
// output + figures stream back as messages. Stopping a run is a hard kill —
// the app terminates this worker and spawns a fresh one.

const post = (message: WorkerResponse) => (self as unknown as Worker).postMessage(message);

self.onmessage = (event: MessageEvent<RunRequest>) => {
	const msg = event.data;
	if (msg.type !== 'run') {
		return;
	}

	// project files live under the VFS default cwd, /project
	const vfs = new VirtualFileSystem();
	for (const file of msg.vfsFiles) {
		vfs.writeFile(file.path, file.content);
	}
	vfs.clearChangeTracking();
	const fileIO = new BrowserFileIOAdapter(vfs);
	const system = new BrowserSystemAdapter(vfs);

	// run under the script's absolute VFS path with its directory as cwd,
	// mirroring the CLI `run` command — sibling functions and relative file
	// I/O then resolve against the script's folder
	const mainAbsPath = vfs.normalizePath(msg.mainFileName);
	const lastSlash = mainAbsPath.lastIndexOf('/');
	vfs.setCwd(lastSlash > 0 ? mainAbsPath.slice(0, lastSlash) : '/');

	try {
		const result = executeCode(
			msg.code,
			{
				onOutput: (text) => post({ type: 'output', text }),
				onDrawnow: (plotInstructions) => post({ type: 'drawnow', plotInstructions }),
				displayResults: true,
				maxIterations: 10_000_000,
				fileIO,
				system,
			},
			msg.workspaceFiles,
			mainAbsPath,
		);
		// onDrawnow flushes (and clears) the instruction buffer mid-run, so
		// result.plotInstructions is only the tail since the last drawnow
		post({ type: 'done', plotInstructions: result.plotInstructions, vfsChanges: fileIO.getChanges() });
	} catch (error) {
		let message: string;
		if (error instanceof RuntimeError) {
			message = [error.toString(), error.snippet].filter(Boolean).join('\n');
		} else {
			message = error instanceof Error ? error.message : String(error);
		}
		post({ type: 'error', message, vfsChanges: fileIO.getChanges() });
	}
};