package bambunfc

import (
	"bytes"
	"encoding/binary"
	"encoding/hex"
	"fmt"
	"math"

	"git.s1d3sw1ped.com/s1d3sw1ped/bambu-nfc/mifare"
)

const BrandBambuLab = "Bambu Lab"

// Tag is one Bambu sticker parsed from a raw MIFARE Classic 1K image.
type Tag struct {
	Brand         string
	ChipUID       string // lowercase hex of the ISO UID
	TrayUID       string // 32 lowercase hex chars (block 9)
	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 block(image []byte, n int) []byte {
	off := n * mifare.BlockSize
	return image[off : off+mifare.BlockSize]
}

func cstr(b []byte) string {
	if i := bytes.IndexByte(b, 0); i >= 0 {
		b = b[:i]
	}
	return string(b)
}

func allZero(b []byte) bool {
	for _, v := range b {
		if v != 0 {
			return false
		}
	}
	return true
}

// Parse reads a Bambu tag from raw NFC: ISO chip UID and the 1024-byte Classic 1K image.
func Parse(uid, image []byte) (Tag, error) {
	var zero Tag
	if len(uid) == 0 {
		return zero, fmt.Errorf("%w: empty", ErrUID)
	}
	if len(image) != mifare.Size1K {
		return zero, fmt.Errorf("%w: want %d got %d", ErrImageSize, mifare.Size1K, len(image))
	}

	b1 := block(image, 1)
	b2 := block(image, 2)
	b4 := block(image, 4)
	b5 := block(image, 5)
	b6 := block(image, 6)
	b9 := block(image, 9)
	b10 := block(image, 10)
	b12 := block(image, 12)
	b14 := block(image, 14)

	material := cstr(b2)
	typ := cstr(b4)
	if material == "" && typ == "" {
		return zero, ErrNotBambu
	}
	if allZero(b9) {
		return zero, fmt.Errorf("%w: tray uid", ErrIncomplete)
	}

	return Tag{
		Brand:      BrandBambuLab,
		ChipUID:    hex.EncodeToString(uid),
		VariantID:  cstr(b1[0:8]),
		MaterialID: cstr(b1[8:16]),
		Material:   material,
		Type:       typ,
		Color: Color{
			R: b5[0], G: b5[1], B: b5[2], A: b5[3],
		},
		WeightG:       int(binary.LittleEndian.Uint16(b5[4:6])),
		DiameterMM:    math.Float32frombits(binary.LittleEndian.Uint32(b5[8:12])),
		TrayUID:       hex.EncodeToString(b9),
		DryC:          int(binary.LittleEndian.Uint16(b6[0:2])),
		DryHours:      int(binary.LittleEndian.Uint16(b6[2:4])),
		BedC:          int(binary.LittleEndian.Uint16(b6[6:8])),
		MaxHotendC:    int(binary.LittleEndian.Uint16(b6[8:10])),
		MinHotendC:    int(binary.LittleEndian.Uint16(b6[10:12])),
		SpoolWidthRaw: binary.LittleEndian.Uint16(b10[4:6]),
		Produced:      cstr(b12),
		LengthM:       int(binary.LittleEndian.Uint16(b14[4:6])),
	}, nil
}