awards

internal/award/wpx.go

@@ -0,0 +1,119 @@
+package award
+
+import "strings"
+
+// wpxPrefix derives the CQ WPX prefix from a callsign. This is an approximation
+// of the official WPX rules — good enough to count distinct prefixes worked:
+//   - standard call: letters+digits up to and including the LAST digit of the
+//     first group (F4BPO→F4, EA8ABC→EA8, 9A1AA→9A1, OH2BH→OH2)
+//   - no digit: first two letters + "0" (RAEM→RA0)
+//   - portable "A/B": a short alpha(+digit) segment is treated as the prefix
+//     designator; a lone-digit segment replaces the call's digit (F4BPO/9→F9)
+func wpxPrefix(call string) string {
+	c := strings.ToUpper(strings.TrimSpace(call))
+	if c == "" {
+		return ""
+	}
+	if strings.Contains(c, "/") {
+		return portablePrefix(c)
+	}
+	return standardPrefix(c)
+}
+
+func portablePrefix(c string) string {
+	parts := strings.Split(c, "/")
+	// Drop pure operating-modifier suffixes.
+	kept := make([]string, 0, len(parts))
+	for _, p := range parts {
+		switch p {
+		case "P", "M", "MM", "AM", "QRP", "A", "R", "B", "LH":
+			continue
+		}
+		if p != "" {
+			kept = append(kept, p)
+		}
+	}
+	if len(kept) == 0 {
+		kept = parts
+	}
+	// Pick a base = the longest segment (the actual call).
+	base := kept[0]
+	for _, p := range kept[1:] {
+		if len(p) > len(base) {
+			base = p
+		}
+	}
+	for _, p := range kept {
+		if p == base {
+			continue
+		}
+		if isAllDigits(p) {
+			// Lone digit replaces the call's region digit: F4BPO/9 → F9.
+			return replaceLastDigit(standardPrefix(base), p)
+		}
+		if len(p) <= 4 && hasLetter(p) {
+			// Prefix designator wins: VP8/F4BPO → VP8 (+digit if missing).
+			return ensureTrailingDigit(p)
+		}
+	}
+	return standardPrefix(base)
+}
+
+// standardPrefix applies the basic WPX rule to a plain callsign: the prefix is
+// the call up to and including its last digit (9A1AA→9A1, EA8ABC→EA8). Standard
+// callsigns carry no digit in the suffix, so "last digit" is the prefix digit.
+func standardPrefix(c string) string {
+	lastDigit := -1
+	for i := 0; i < len(c); i++ {
+		if c[i] >= '0' && c[i] <= '9' {
+			lastDigit = i
+		}
+	}
+	if lastDigit < 0 {
+		// No digit at all: first two letters + 0.
+		if len(c) >= 2 {
+			return c[:2] + "0"
+		}
+		return c + "0"
+	}
+	return c[:lastDigit+1]
+}
+
+func ensureTrailingDigit(p string) string {
+	for i := 0; i < len(p); i++ {
+		if p[i] >= '0' && p[i] <= '9' {
+			return p
+		}
+	}
+	return p + "0"
+}
+
+func replaceLastDigit(prefix, digit string) string {
+	for i := len(prefix) - 1; i >= 0; i-- {
+		if prefix[i] >= '0' && prefix[i] <= '9' {
+			return prefix[:i] + digit
+		}
+	}
+	return prefix + digit
+}
+
+func isAllDigits(s string) bool {
+	if s == "" {
+		return false
+	}
+	for i := 0; i < len(s); i++ {
+		if s[i] < '0' || s[i] > '9' {
+			return false
+		}
+	}
+	return true
+}
+
+func hasLetter(s string) bool {
+	for i := 0; i < len(s); i++ {
+		if (s[i] >= 'A' && s[i] <= 'Z') || (s[i] >= 'a' && s[i] <= 'z') {
+			return true
+		}
+	}
+	return false
+}