export function readFileAsync(file) {
	return new Promise((resolve, reject) => {
		let reader = new FileReader();
		reader.onload = () => {
			resolve(reader.result);
		};
		reader.onerror = reject;
		reader.readAsDataURL(file);
	});
}

export function aggregateWordFixations(data) {
	//slicing off first fixation since it is the calibration in center
	let sorted = data.filter( item => item.word_id ).slice(1).sort((a,b) => a.word_id-b.word_id);
	//add first back in
	sorted.unshift(data[0]);
	//aggregate fixations for same words in bags
	let aggregate = sorted.reduce( (acc, val) => {
		if (acc[0].length == 0 || val.word_id == acc[acc.length-1][0].word_id) {
			acc[acc.length-1].push(val)
		} else {
			acc.push([val]);
		}
		return acc;
	}, [[]]);
	//average fixation coordinates and sum duration for each bag
	return aggregate.map( bag => {
		let word = bag[0].word;
		let word_id = bag[0].word_id;
		let x=0;
		let y=0;
		let dur=0;
		for (let fixation of bag) {
			x += fixation.x/bag.length;
			y += fixation.y/bag.length;
			dur += fixation.dur;
		}
		return {x, y, dur, word_id, word};
	});
}