import _flatten from 'lodash/flatten';
import { validateEmail } from '.';

interface dataTypes {
	value: string;
	isInvalid: boolean;
}

const parseCSV = (file: File, delimiter: string): Promise<dataTypes[]> => {
	return new Promise((resolve) => {
		const reader = new FileReader();

		// When the FileReader has loaded the file...
		reader.onload = (e: any) => {
			// Split the result to an array of lines
			const lines = e.target.result.split('\n');
			// Split the lines themselves by the specified
			// delimiter, such as a comma
			let result = lines.map((line: string) => line.split(delimiter));
			// As the FileReader reads asynchronously,
			// we can't just return the result; instead,
			// we're passing it to a callback function
			result = _flatten(result);
			resolve(
				result.map((email: string) => {
					return {
						value: email.trim(),
						isInvalid: !validateEmail(email.trim()),
					};
				}),
			);
		};

		// Read the file content as a single string
		reader.readAsText(file);
	});
};

export default parseCSV;