"use strict";

// FIXME: Clearly document that this only splits lines in *strings*, not eg. Buffers (and make a separate split-lines-buffer package for that, as it requires a very different implementation)

const lastItem = require("last-item");

const pipe = require("@promistream/pipe");
const map = require("@promistream/map");
const buffer = require("@promistream/buffer");
const lastWill = require("@promistream/last-will");

const { validateOptions, validateValue } = require("@validatem/core");
const defaultTo = require("@validatem/default-to");
const isBoolean = require("@validatem/is-boolean");
const isString = require("@validatem/is-string");

module.exports = function splitLines(_options) {
	let options = validateOptions(arguments, [
		defaultTo({}), {
			stripCarriageReturn: [ defaultTo(true), isBoolean ]
		}
	]);

	let stringBuffer = "";

	return pipe([
		map((value) => {
			validateValue(value, [ isString ]); // FIXME: Turn this into a clearer error

			stringBuffer += value;

			let lines = stringBuffer.split("\n");
			
			if (lines.length > 1) {
				let completedLines = lines.slice(0, -1);
				stringBuffer = lastItem(lines);

				if (options.stripCarriageReturn) {
					return completedLines.map((line) => {
						return line.replace(/\r+$/g, "");
					});
				} else {
					return completedLines;
				}
			} else {
				return [];
			}
		}),
		buffer(),
		lastWill(() => {
			return stringBuffer;
		})
	]);
};