import {createWorker} from 'tesseract.js';
import {AbortablePromise, Ai} from './ai.ts';

export class Vision {

	constructor(private ai: Ai) {}

	/**
	 * Convert image to text using Optical Character Recognition
	 * @param {string} path Path to image
	 * @returns {AbortablePromise<string | null>} Promise of extracted text with abort method
	 */
	ocr(path: string): AbortablePromise<string | null> {
		let worker: any;
		let reject: (err: any) => void;

		const handler = (err: Error) => {
			if(err.stack?.includes('tesseract.js')) {
				process.off('uncaughtException', handler);
				reject?.(err);
				return;
			}
			throw err;
		};
		process.on('uncaughtException', handler);

		const p = (async () => {
			worker = await createWorker(this.ai.options.ocr || 'eng', 2, {cachePath: this.ai.options.path});
			return await new Promise<string | null>((res, rej) => {
				reject = rej;
				worker.recognize(path)
					.then(({data}: any) => res(data.text.trim() || null))
					.catch(rej);
			});
		})().finally(() => {
			process.off('uncaughtException', handler);
			worker?.terminate();
		});

		return Object.assign(p, {abort: () => worker?.terminate()});
	}
}