package kyc

import (
	"crypto/md5"
	"encoding/base64"
	"encoding/hex"
	"encoding/json"
	"errors"
	"fmt"
	"nixcn-cms/internal/cryptography"
	"unicode/utf8"

	"github.com/spf13/viper"
)

func DecodeB64Json(b64Json string) (*KycInfo, error) {
	rawJson, err := base64.StdEncoding.DecodeString(b64Json)
	if err != nil {
		return nil, errors.New("invalid base64 json")
	}

	var kyc KycInfo
	if err := json.Unmarshal(rawJson, &kyc); err != nil {
		return nil, errors.New("invalid json structure")
	}

	return &kyc, nil
}

func EncodeAES(kyc *KycInfo) (*string, error) {
	plainJson, err := json.Marshal(kyc)
	if err != nil {
		return nil, err
	}

	aesKey := viper.GetString("secrets.kyc_info_key")
	encrypted, err := cryptography.AESCBCEncrypt(plainJson, []byte(aesKey))
	if err != nil {
		return nil, err
	}

	return &encrypted, nil
}

func DecodeAES(cipherStr string) (*KycInfo, error) {
	aesKey := viper.GetString("secrets.kyc_info_key")
	plainBytes, err := cryptography.AESCBCDecrypt(cipherStr, []byte(aesKey))
	if err != nil {
		return nil, err
	}

	var kyc KycInfo
	if err := json.Unmarshal(plainBytes, &kyc); err != nil {
		return nil, errors.New("invalid decrypted json")
	}

	return &kyc, nil
}

func MD5AliEnc(kyc *KycInfo) (*MD5Ali, error) {
	if kyc.Type != "Chinese" {
		return nil, nil
	}

	// MD5 Legal Name rule: First Chinese char md5enc, remaining plain, at least 2 Chinese chars
	if len(kyc.LegalName) < 2 || utf8.RuneCountInString(kyc.LegalName) < 2 {
		return nil, fmt.Errorf("input string must have at least 2 Chinese characters")
	}

	lnFirstRune, size := utf8.DecodeRuneInString(kyc.LegalName)
	if lnFirstRune == utf8.RuneError {
		return nil, fmt.Errorf("invalid first character")
	}

	lnHash := md5.New()
	lnHash.Write([]byte(string(lnFirstRune)))
	lnFirstHash := hex.EncodeToString(lnHash.Sum(nil))

	lnRemaining := kyc.LegalName[size:]

	ln := lnFirstHash + lnRemaining

	// MD5 Resident Id rule: First 6 char plain, middle birthdate md5enc, last 4 char plain, at least 18 chars
	if len(kyc.ResidentId) < 18 {
		return nil, fmt.Errorf("input string must have at least 18 characters")
	}

	ridPrefix := kyc.ResidentId[:6]
	ridSuffix := kyc.ResidentId[len(kyc.ResidentId)-4:]
	ridMiddle := kyc.ResidentId[6 : len(kyc.ResidentId)-4]

	ridHash := md5.New()
	ridHash.Write([]byte(ridMiddle))
	ridMiddleHash := hex.EncodeToString(ridHash.Sum(nil))

	rid := ridPrefix + ridMiddleHash + ridSuffix

	// Aliyun Id2MetaVerify API Params
	var kycAli MD5Ali
	kycAli.ParamType = "md5"
	kycAli.UserName = ln
	kycAli.IdentifyNum = rid

	return &kycAli, nil
}