package Seeder

import (
	"bytes"
	"crypto/aes"
	"crypto/cipher"
	"crypto/rand"
	"crypto/rsa"
	"crypto/sha512"
	"encoding/pem"
	"hash"

	"git.tovijaeschke.xyz/tovi/Envelope/Backend/Database"
	"git.tovijaeschke.xyz/tovi/Envelope/Backend/Models"
	"github.com/gofrs/uuid"
)

// EncryptWithPublicKey encrypts data with public key
func encryptWithPublicKey(msg []byte, pub *rsa.PublicKey) []byte {
	var (
		hash hash.Hash
	)

	hash = sha512.New()
	ciphertext, err := rsa.EncryptOAEP(hash, rand.Reader, pub, msg, nil)
	if err != nil {
		panic(err)
	}
	return ciphertext
}

func PKCS5Padding(ciphertext []byte, blockSize int, after int) []byte {
	var (
		padding int
		padtext []byte
	)
	padding = (blockSize - len(ciphertext)%blockSize)
	padtext = bytes.Repeat([]byte{byte(padding)}, padding)
	return append(ciphertext, padtext...)
}

func seedMessage(primaryUser, secondaryUser Models.User, threadID uuid.UUID, i int) error {
	var (
		messageKey  Models.Message
		messageData Models.MessageData

		block    cipher.Block
		mode     cipher.BlockMode
		pemBlock *pem.Block

		plaintext  string
		ciphertext []byte

		bKey       []byte
		bIV        []byte
		bPlaintext []byte

		err error
	)

	plaintext = "Test Message"

	bKey = make([]byte, 32)
	_, err = rand.Read(bKey)
	if err != nil {
		panic(err)
	}
	bIV = make([]byte, 16)
	_, err = rand.Read(bIV)
	if err != nil {
		panic(err)
	}
	bPlaintext = PKCS5Padding([]byte(plaintext), aes.BlockSize, len(plaintext))

	pemBlock = &pem.Block{
		Type:  "AES KEY",
		Bytes: bKey,
	}

	block, err = aes.NewCipher(bKey)
	if err != nil {
		panic(err)
	}

	ciphertext = make([]byte, len(bPlaintext))

	mode = cipher.NewCBCEncrypter(block, bIV)

	mode.CryptBlocks(ciphertext, bPlaintext)

	messageData = Models.MessageData{
		Data: ciphertext,
	}

	messageKey = Models.Message{
		UserID:           primaryUser.ID,
		MessageData:      messageData,
		MessageType:      "sender",
		RelationalUserId: encryptWithPublicKey(secondaryUser.ID.Bytes(), decodedPublicKey),
		SymmetricKey:     string(pem.EncodeToMemory(pemBlock)),
	}

	return Database.CreateMessage(&messageKey)
}

func SeedMessages() {
	var (
		primaryUser   Models.User
		secondaryUser Models.User
		threadID      uuid.UUID
		i             int
		err           error
	)

	primaryUser, err = Database.GetUserByUsername("testUser")
	if err != nil {
		panic(err)
	}

	secondaryUser, err = Database.GetUserByUsername("testUser2")
	if err != nil {
		panic(err)
	}

	threadID, err = uuid.NewV4()
	if err != nil {
		panic(err)
	}

	for i = 0; i <= 20; i++ {
		err = seedMessage(primaryUser, secondaryUser, threadID, i)
		if err != nil {
			panic(err)
		}
	}
}