first commit

internal/web/format.go

@@ -0,0 +1,127 @@
+package web
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+	"time"
+)
+
+var currencySymbols = map[string]string{
+	"USD": "$", "GBP": "£", "EUR": "€", "JPY": "¥",
+}
+
+func currencySymbol(currency string) string {
+	if sym, ok := currencySymbols[currency]; ok {
+		return sym
+	}
+	return currency + " "
+}
+
+// money formats an amount in the given currency with thousands separators,
+// e.g. money(-1234.5, "GBP") -> "-£1,234.50".
+func money(v float64, currency string) string {
+	neg := v < 0
+	if neg {
+		v = -v
+	}
+	s := strconv.FormatFloat(v, 'f', 2, 64)
+	intPart, decPart, _ := strings.Cut(s, ".")
+	var out []byte
+	n := len(intPart)
+	for i := 0; i < n; i++ {
+		if i > 0 && (n-i)%3 == 0 {
+			out = append(out, ',')
+		}
+		out = append(out, intPart[i])
+	}
+	res := currencySymbol(currency) + string(out) + "." + decPart
+	if neg {
+		res = "-" + res
+	}
+	return res
+}
+
+// amt formats a crypto quantity, trimming trailing zeros.
+func amt(v float64) string {
+	s := strconv.FormatFloat(v, 'f', 8, 64)
+	s = strings.TrimRight(s, "0")
+	s = strings.TrimRight(s, ".")
+	if s == "" || s == "-" {
+		s = "0"
+	}
+	return s
+}
+
+func pctStr(v *float64) string {
+	if v == nil {
+		return "—"
+	}
+	sign := ""
+	if *v > 0 {
+		sign = "+"
+	}
+	return fmt.Sprintf("%s%.2f%%", sign, *v)
+}
+
+func pctClass(v *float64) string {
+	if v == nil {
+		return "flat"
+	}
+	return signClass(*v)
+}
+
+func signClass(v float64) string {
+	if v > 0 {
+		return "gain"
+	}
+	if v < 0 {
+		return "loss"
+	}
+	return "flat"
+}
+
+func dateStr(t time.Time) string {
+	return t.Format("Jan 2, 2006")
+}
+
+// capitalize upper-cases the first letter of an entry type ("withdrawal" -> "Withdrawal").
+func capitalize(s string) string {
+	if s == "" {
+		return s
+	}
+	return strings.ToUpper(s[:1]) + s[1:]
+}
+
+// sortVal renders a float64 or *float64 as a plain number string for a
+// data-sort-value attribute, so the client-side table sort compares numbers
+// rather than formatted display text ("£1,234.56", "+3.21%", "—").
+func sortVal(v interface{}) string {
+	switch x := v.(type) {
+	case float64:
+		return strconv.FormatFloat(x, 'f', -1, 64)
+	case *float64:
+		if x == nil {
+			return ""
+		}
+		return strconv.FormatFloat(*x, 'f', -1, 64)
+	default:
+		return fmt.Sprint(v)
+	}
+}
+
+func holdDuration(t time.Time) string {
+	days := int(time.Since(t).Hours() / 24)
+	switch {
+	case days < 1:
+		return "<1 day"
+	case days == 1:
+		return "1 day"
+	case days < 30:
+		return fmt.Sprintf("%d days", days)
+	case days < 365:
+		return fmt.Sprintf("%d mo", days/30)
+	default:
+		return fmt.Sprintf("%.1f yr", float64(days)/365)
+	}
+}