package wechat

import (
	"crypto/aes"
	"crypto/cipher"
	"crypto/rand"
	"encoding/base64"
	"testing"
)

func TestDecryptPhone(t *testing.T) {
	key := make([]byte, 16)
	iv := make([]byte, 16)
	_, _ = rand.Read(key)
	_, _ = rand.Read(iv)
	plain := []byte(`{"phoneNumber":"13800138000","purePhoneNumber":"13800138000","watermark":{"appid":"wxapp"}}`)
	padded := pkcs7Pad(plain, aes.BlockSize)
	block, err := aes.NewCipher(key)
	if err != nil {
		t.Fatal(err)
	}
	enc := make([]byte, len(padded))
	cipher.NewCBCEncrypter(block, iv).CryptBlocks(enc, padded)

	phone, err := DecryptPhone(
		base64.StdEncoding.EncodeToString(key),
		base64.StdEncoding.EncodeToString(enc),
		base64.StdEncoding.EncodeToString(iv),
		"wxapp",
	)
	if err != nil {
		t.Fatal(err)
	}
	if phone != "13800138000" {
		t.Fatalf("got %s", phone)
	}
}

func pkcs7Pad(b []byte, block int) []byte {
	n := block - (len(b) % block)
	out := make([]byte, len(b)+n)
	copy(out, b)
	for i := 0; i < n; i++ {
		out[len(b)+i] = byte(n)
	}
	return out
}