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
}