done purchases remove, ocr scan, read image

express-server/node_modules/string-similarity/compare-strings.js

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+module.exports = {
+	compareTwoStrings,
+	findBestMatch
+};
+
+function compareTwoStrings(first, second) {
+	first = first.replace(/\s+/g, '')
+	second = second.replace(/\s+/g, '')
+
+	if (!first.length && !second.length) return 1;                   // if both are empty strings
+	if (!first.length || !second.length) return 0;                   // if only one is empty string
+	if (first === second) return 1;       							 // identical
+	if (first.length === 1 && second.length === 1) return 0;         // both are 1-letter strings
+	if (first.length < 2 || second.length < 2) return 0;			 // if either is a 1-letter string
+
+	let firstBigrams = new Map();
+	for (let i = 0; i < first.length - 1; i++) {
+		const bigram = first.substr(i, 2);
+		const count = firstBigrams.has(bigram)
+			? firstBigrams.get(bigram) + 1
+			: 1;
+
+		firstBigrams.set(bigram, count);
+	};
+
+	let intersectionSize = 0;
+	for (let i = 0; i < second.length - 1; i++) {
+		const bigram = second.substr(i, 2);
+		const count = firstBigrams.has(bigram)
+			? firstBigrams.get(bigram)
+			: 0;
+
+		if (count > 0) {
+			firstBigrams.set(bigram, count - 1);
+			intersectionSize++;
+		}
+	}
+
+	return (2.0 * intersectionSize) / (first.length + second.length - 2);
+}
+
+function findBestMatch(mainString, targetStrings) {
+	if (!areArgsValid(mainString, targetStrings)) throw new Error('Bad arguments: First argument should be a string, second should be an array of strings');
+	
+	const ratings = [];
+	let bestMatchIndex = 0;
+
+	for (let i = 0; i < targetStrings.length; i++) {
+		const currentTargetString = targetStrings[i];
+		const currentRating = compareTwoStrings(mainString, currentTargetString)
+		ratings.push({target: currentTargetString, rating: currentRating})
+		if (currentRating > ratings[bestMatchIndex].rating) {
+			bestMatchIndex = i
+		}
+	}
+	
+	
+	const bestMatch = ratings[bestMatchIndex]
+	
+	return { ratings, bestMatch, bestMatchIndex };
+}
+
+function flattenDeep(arr) {
+	return Array.isArray(arr) ? arr.reduce((a, b) => a.concat(flattenDeep(b)), []) : [arr];
+}
+
+function areArgsValid(mainString, targetStrings) {
+	if (typeof mainString !== 'string') return false;
+	if (!Array.isArray(targetStrings)) return false;
+	if (!targetStrings.length) return false;
+	if (targetStrings.find(s => typeof s !== 'string')) return false;
+	return true;
+}
+
+function letterPairs(str) {
+	const pairs = [];
+	for (let i = 0, max = str.length - 1; i < max; i++) pairs[i] = str.substring(i, i + 2);
+	return pairs;
+}
+
+function wordLetterPairs(str) {
+	const pairs = str.toUpperCase().split(' ').map(letterPairs);
+	return flattenDeep(pairs);
+}