WalletApi: getMultisigInfo entry for gui wallets

WalletApi: makeMultisig call introduced

WalletApi: finalizeMultisig call introduced

WalletApi: new calls exportMultisigImages and importMultisigImages

WalletApi: method to return multisig wallet creation state

WalletApi: create multisig transaction, sign multisig transaction, commit transaction and get multisig data are added

WalletApi: identation and style fixes

src/wallet/api/wallet2_api.h

@@ -100,6 +100,30 @@ struct PendingTransaction
     virtual uint64_t txCount() const = 0;
     virtual std::vector<uint32_t> subaddrAccount() const = 0;
     virtual std::vector<std::set<uint32_t>> subaddrIndices() const = 0;
+
+    /**
+     * @brief multisigSignData
+     * @return encoded multisig transaction with signers' keys.
+     *         Transfer this data to another wallet participant to sign it.
+     *         Assumed use case is:
+     *         1. Initiator:
+     *              auto data = pendingTransaction->multisigSignData();
+     *         2. Signer1:
+     *              pendingTransaction = wallet->restoreMultisigTransaction(data);
+     *              pendingTransaction->signMultisigTx();
+     *              auto signed = pendingTransaction->multisigSignData();
+     *         3. Signer2:
+     *              pendingTransaction = wallet->restoreMultisigTransaction(signed);
+     *              pendingTransaction->signMultisigTx();
+     *              pendingTransaction->commit();
+     */
+    virtual std::string multisigSignData() = 0;
+    virtual void signMultisigTx() = 0;
+    /**
+     * @brief signersKeys
+     * @return vector of base58-encoded signers' public keys
+     */
+    virtual std::vector<std::string> signersKeys() const = 0;
 };
 
 /**
@@ -291,6 +315,15 @@ struct SubaddressAccount
     virtual void refresh() = 0;
 };
 
+struct MultisigState {
+    MultisigState() : isMultisig(false), isReady(false), threshold(0), total(0) {}
+
+    bool isMultisig;
+    bool isReady;
+    uint32_t threshold;
+    uint32_t total;
+};
+
 struct WalletListener
 {
     virtual ~WalletListener() = 0;
@@ -630,6 +663,48 @@ struct Wallet
      */
     virtual void setSubaddressLabel(uint32_t accountIndex, uint32_t addressIndex, const std::string &label) = 0;
 
+    /**
+     * @brief multisig - returns current state of multisig wallet creation process
+     * @return MultisigState struct
+     */
+    virtual MultisigState multisig() const = 0;
+    /**
+     * @brief getMultisigInfo
+     * @return serialized and signed multisig info string
+     */
+    virtual std::string getMultisigInfo() const = 0;
+    /**
+     * @brief makeMultisig - switches wallet in multisig state. The one and only creation phase for N / N wallets
+     * @param info - vector of multisig infos from other participants obtained with getMulitisInfo call
+     * @param threshold - number of required signers to make valid transaction. Must be equal to number of participants (N) or N - 1
+     * @return in case of N / N wallets returns empty string since no more key exchanges needed. For N - 1 / N wallets returns base58 encoded extra multisig info
+     */
+    virtual std::string makeMultisig(const std::vector<std::string>& info, uint32_t threshold) = 0;
+    /**
+     * @brief finalizeMultisig - finalizes N - 1 / N multisig wallets creation
+     * @param extraMultisigInfo - wallet participants' extra multisig info obtained with makeMultisig call
+     * @return true if success
+     */
+    virtual bool finalizeMultisig(const std::vector<std::string>& extraMultisigInfo) = 0;
+    /**
+     * @brief exportMultisigImages - exports transfers' key images
+     * @param images - output paramter for hex encoded array of images
+     * @return true if success
+     */
+    virtual bool exportMultisigImages(std::string& images) = 0;
+    /**
+     * @brief importMultisigImages - imports other participants' multisig images
+     * @param images - array of hex encoded arrays of images obtained with exportMultisigImages
+     * @return number of imported images
+     */
+    virtual size_t importMultisigImages(const std::vector<std::string>& images) = 0;
+
+    /**
+     * @brief restoreMultisigTransaction creates PendingTransaction from signData
+     * @param signData encrypted unsigned transaction. Obtained with PendingTransaction::multisigSignData
+     * @return PendingTransaction
+     */
+    virtual PendingTransaction*  restoreMultisigTransaction(const std::string& signData) = 0;
     /*!
      * \brief createTransaction creates transaction. if dst_addr is an integrated address, payment_id is ignored
      * \param dst_addr          destination address as string