Add bambu-nfc dump parse, Key-A HKDF, and spool merge.

Parse filanfc-dump/v1 zip/JSON, Bambu 1K images, and merge stickers by tray UID. dump and mifare packages stay importable for a later common library.

merge.go

@@ -0,0 +1,107 @@
+package bambunfc
+
+import (
+	"fmt"
+	"slices"
+)
+
+// Spool is one physical filament roll (both stickers merged).
+type Spool struct {
+	Brand         string
+	TrayUID       string
+	ChipUIDs      []string
+	Type          string
+	Material      string
+	MaterialID    string
+	VariantID     string
+	Color         Color
+	WeightG       int
+	DiameterMM    float32
+	LengthM       int
+	MinHotendC    int
+	MaxHotendC    int
+	BedC          int
+	DryC          int
+	DryHours      int
+	Produced      string
+	SpoolWidthRaw uint16
+}
+
+func spoolKey(t Tag) string {
+	return t.Brand + "\x00" + t.TrayUID
+}
+
+func sameFilament(a, b Tag) bool {
+	return a.Type == b.Type &&
+		a.Material == b.Material &&
+		a.Color == b.Color &&
+		a.WeightG == b.WeightG
+}
+
+func tagToSpool(t Tag) Spool {
+	return Spool{
+		Brand:         t.Brand,
+		TrayUID:       t.TrayUID,
+		ChipUIDs:      []string{t.ChipUID},
+		Type:          t.Type,
+		Material:      t.Material,
+		MaterialID:    t.MaterialID,
+		VariantID:     t.VariantID,
+		Color:         t.Color,
+		WeightG:       t.WeightG,
+		DiameterMM:    t.DiameterMM,
+		LengthM:       t.LengthM,
+		MinHotendC:    t.MinHotendC,
+		MaxHotendC:    t.MaxHotendC,
+		BedC:          t.BedC,
+		DryC:          t.DryC,
+		DryHours:      t.DryHours,
+		Produced:      t.Produced,
+		SpoolWidthRaw: t.SpoolWidthRaw,
+	}
+}
+
+// Merge groups tags by brand + tray UID into spools.
+func Merge(tags []Tag) ([]Spool, error) {
+	order := make([]string, 0)
+	groups := make(map[string][]Tag)
+	for _, t := range tags {
+		if t.TrayUID == "" {
+			return nil, fmt.Errorf("%w: empty tray uid chip %s", ErrIncomplete, t.ChipUID)
+		}
+		k := spoolKey(t)
+		if _, ok := groups[k]; !ok {
+			order = append(order, k)
+		}
+		groups[k] = append(groups[k], t)
+	}
+
+	spools := make([]Spool, 0, len(order))
+	for _, k := range order {
+		g := groups[k]
+		s := tagToSpool(g[0])
+		uids := map[string]struct{}{g[0].ChipUID: {}}
+		for _, t := range g[1:] {
+			if !sameFilament(g[0], t) {
+				return nil, fmt.Errorf("%w: tray %s", ErrConflict, t.TrayUID)
+			}
+			uids[t.ChipUID] = struct{}{}
+		}
+		s.ChipUIDs = make([]string, 0, len(uids))
+		for u := range uids {
+			s.ChipUIDs = append(s.ChipUIDs, u)
+		}
+		slices.Sort(s.ChipUIDs)
+		spools = append(spools, s)
+	}
+	slices.SortFunc(spools, func(a, b Spool) int {
+		if a.TrayUID < b.TrayUID {
+			return -1
+		}
+		if a.TrayUID > b.TrayUID {
+			return 1
+		}
+		return 0
+	})
+	return spools, nil
+}