chore(updater): move updater packages to pkg/updaters/<name>

pkg/updaters/purevpn/compare.go

@@ -0,0 +1,59 @@
+package purevpn
+
+import (
+	"strings"
+	"unicode"
+
+	"golang.org/x/text/runes"
+	"golang.org/x/text/transform"
+	"golang.org/x/text/unicode/norm"
+)
+
+// comparePlaceNames returns true if strings are within 1 edit
+// distance after normalization.
+func comparePlaceNames(a, b string) bool {
+	normA := normalize(a)
+	normB := normalize(b)
+	return normA == normB || levenshteinDistance(normA, normB) <= 1
+}
+
+// normalize removes accents, trims space, and lowercases the string.
+func normalize(s string) string {
+	transformer := transform.Chain(norm.NFD, runes.Remove(runes.In(unicode.Mn)), norm.NFC)
+	result, _, err := transform.String(transformer, s)
+	if err != nil {
+		panic(err)
+	}
+	return strings.ToLower(strings.TrimSpace(result))
+}
+
+// levenshteinDistance calculates the edit distance
+// between two strings a and b.
+func levenshteinDistance(a, b string) int {
+	switch {
+	case len(a) == 0:
+		return len(b)
+	case len(b) == 0:
+		return len(a)
+	}
+
+	column := make([]int, len(b)+1)
+	for i := 0; i <= len(b); i++ {
+		column[i] = i
+	}
+
+	for i := 1; i <= len(a); i++ {
+		column[0] = i
+		lastValue := i - 1
+		for j := 1; j <= len(b); j++ {
+			oldValue := column[j]
+			cost := 0
+			if a[i-1] != b[j-1] {
+				cost = 1
+			}
+			column[j] = min(column[j]+1, min(column[j-1]+1, lastValue+cost))
+			lastValue = oldValue
+		}
+	}
+	return column[len(b)]
+}