package eth

import (
	"bytes"
	"encoding/hex"
	"math/big"
	"unicode"
	"unicode/utf8"
)

func parseSimpleNumericProperty(data string) *big.Int {
	if has0xPrefix(data) {
		data = data[2:]
	}
	if len(data) > 64 {
		data = data[:64]
	}
	if len(data) == 64 {
		var n big.Int
		_, ok := n.SetString(data, 16)
		if ok {
			return &n
		}
	}
	return nil
}

func parseSimpleStringProperty(data string) string {
	if has0xPrefix(data) {
		data = data[2:]
	}
	if len(data) > 128 {
		n := parseSimpleNumericProperty(data[64:128])
		if n != nil {
			l := n.Uint64()
			if l > 0 && 2*int(l) <= len(data)-128 {
				b, err := hex.DecodeString(data[128 : 128+2*l])
				if err == nil {
					return string(b)
				}
			}
		}
	}
	// allow string properties as UTF-8 data
	b, err := hex.DecodeString(data)
	if err == nil {
		i := bytes.Index(b, []byte{0})
		if i > 32 {
			i = 32
		}
		if i > 0 {
			b = b[:i]
		}
		if utf8.Valid(b) {
			return string(b)
		}
	}
	return ""
}

func Decamel(s string) string {
	var b bytes.Buffer
	splittable := false
	for _, v := range s {
		if splittable && unicode.IsUpper(v) {
			b.WriteByte(' ')
		}
		b.WriteRune(v)
		splittable = unicode.IsLower(v) || unicode.IsNumber(v)
	}
	return b.String()
}