Initial commit

internal/feed/utils.go

@@ -0,0 +1,79 @@
+package feed
+
+import (
+	"errors"
+	"fmt"
+	"net/url"
+	"slices"
+	"strings"
+)
+
+var (
+	ErrNoContent      = errors.New("failed to retrieve any content")
+	ErrPartialContent = errors.New("failed to retrieve some of the content")
+)
+
+func percentChange(current, previous float64) float64 {
+	return (current/previous - 1) * 100
+}
+
+func extractDomainFromUrl(u string) string {
+	if u == "" {
+		return ""
+	}
+
+	parsed, err := url.Parse(u)
+
+	if err != nil {
+		return ""
+	}
+
+	return strings.TrimPrefix(parsed.Host, "www.")
+}
+
+func SvgPolylineCoordsFromYValues(width float64, height float64, values []float64) string {
+	if len(values) < 2 {
+		return ""
+	}
+
+	verticalPadding := height * 0.02
+	height -= verticalPadding * 2
+	coordinates := make([]string, len(values))
+	distanceBetweenPoints := width / float64(len(values)-1)
+	min := slices.Min(values)
+	max := slices.Max(values)
+
+	for i := range values {
+		coordinates[i] = fmt.Sprintf(
+			"%.2f,%.2f",
+			float64(i)*distanceBetweenPoints,
+			((max-values[i])/(max-min))*height+verticalPadding,
+		)
+	}
+
+	return strings.Join(coordinates, " ")
+}
+
+func maybeCopySliceWithoutZeroValues[T int | float64](values []T) []T {
+	if len(values) == 0 {
+		return values
+	}
+
+	for i := range values {
+		if values[i] != 0 {
+			continue
+		}
+
+		c := make([]T, 0, len(values)-1)
+
+		for i := range values {
+			if values[i] != 0 {
+				c = append(c, values[i])
+			}
+		}
+
+		return c
+	}
+
+	return values
+}