panel — open-source game server manager (public release)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

pkg/regionmedic/localize.go

@@ -0,0 +1,103 @@
+package regionmedic
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+// floorMod returns the mathematical (floored) modulo, always in [0, m).
+func floorMod(a, m int) int { return ((a % m) + m) % m }
+
+// floorDiv returns the floored integer division (rounds toward -inf).
+func floorDiv(a, m int) int {
+	q := a / m
+	if (a%m != 0) && ((a < 0) != (m < 0)) {
+		q--
+	}
+	return q
+}
+
+// RegionCoord identifies a region file r.<X>.<Z>.7rg in the 32×32-chunk grid.
+type RegionCoord struct {
+	X int `json:"x"`
+	Z int `json:"z"`
+}
+
+// FileName returns the on-disk region filename, e.g. "r.-2.0.7rg".
+func (rc RegionCoord) FileName() string { return fmt.Sprintf("r.%d.%d.7rg", rc.X, rc.Z) }
+
+// String returns the canonical region id, e.g. "r.-2.0".
+func (rc RegionCoord) String() string { return fmt.Sprintf("r.%d.%d", rc.X, rc.Z) }
+
+// RegionForChunk maps a global chunk coordinate to its region (floored /32).
+func RegionForChunk(cx, cz int) RegionCoord {
+	return RegionCoord{X: floorDiv(cx, RegionSide), Z: floorDiv(cz, RegionSide)}
+}
+
+// ParseRegionFileName parses "r.<X>.<Z>.7rg" -> RegionCoord. ok=false otherwise.
+// Handles negative coordinates, e.g. "r.-2.0.7rg" -> {X:-2, Z:0}.
+func ParseRegionFileName(name string) (RegionCoord, bool) {
+	if !strings.HasPrefix(name, "r.") || !strings.HasSuffix(name, ".7rg") {
+		return RegionCoord{}, false
+	}
+	mid := strings.TrimSuffix(strings.TrimPrefix(name, "r."), ".7rg")
+	// mid is "<X>.<Z>" where X and Z may be negative. Split on the dot that
+	// separates them: there is exactly one '.' between two integers.
+	x, z, ok := splitTwoInts(mid)
+	if !ok {
+		return RegionCoord{}, false
+	}
+	return RegionCoord{X: x, Z: z}, true
+}
+
+// ParseErrorBackup parses 7DTD chunk-salvage filenames written on a failed load:
+//
+//	error_backup_<cx>_<cz>.comp.bak
+//	error_backup_<cx>_<cz>.uncomp.bak
+//
+// returning the global chunk coordinates. ok=false if name is not such a file.
+func ParseErrorBackup(name string) (cx, cz int, ok bool) {
+	const pfx = "error_backup_"
+	if !strings.HasPrefix(name, pfx) {
+		return 0, 0, false
+	}
+	rest := name[len(pfx):]
+	// Strip the known suffixes.
+	switch {
+	case strings.HasSuffix(rest, ".comp.bak"):
+		rest = strings.TrimSuffix(rest, ".comp.bak")
+	case strings.HasSuffix(rest, ".uncomp.bak"):
+		rest = strings.TrimSuffix(rest, ".uncomp.bak")
+	default:
+		return 0, 0, false
+	}
+	// rest is "<cx>_<cz>" with possibly-negative ints separated by '_'.
+	i := strings.LastIndex(rest, "_")
+	if i <= 0 || i >= len(rest)-1 {
+		return 0, 0, false
+	}
+	a, err1 := strconv.Atoi(rest[:i])
+	b, err2 := strconv.Atoi(rest[i+1:])
+	if err1 != nil || err2 != nil {
+		return 0, 0, false
+	}
+	return a, b, true
+}
+
+// splitTwoInts splits "<a>.<b>" into two ints where each may be negative.
+// The separator is the first '.' that is not a leading minus sign position.
+func splitTwoInts(s string) (int, int, bool) {
+	// Find a '.' that splits into two parseable ints. Scan candidate dots.
+	for i := 1; i < len(s); i++ {
+		if s[i] != '.' {
+			continue
+		}
+		a, err1 := strconv.Atoi(s[:i])
+		b, err2 := strconv.Atoi(s[i+1:])
+		if err1 == nil && err2 == nil {
+			return a, b, true
+		}
+	}
+	return 0, 0, false
+}