Problem: impossible to track wallet balance (CRO-53) WIP

Solution: client-core WIP infrastructure (balance_service...) described in README

client-core/Cargo.toml

@@ -16,8 +16,8 @@ blake2 = "0.8"
 hex = "0.3"
 zeroize = "0.6"
 zeroize_derive = "0.1"
+byteorder = "1.3"
 sled = { version = "0.19", optional = true }
 
 [features]
 default = ["sled"]
-hash-map = []

client-core/README.md

@@ -0,0 +1,96 @@
+# Crypto.com Chain Client
+
+This crate exposes following functionalities for interacting with Crypto.com Chain:
+- Wallet creation
+- Address generation
+- Transaction syncing and storage
+- Balance tracking
+- Transaction creation and signing
+
+## Design
+
+Below is a high level design diagram of this crate:
+
+<div class = "design_diagram">
+    <img src="./client_design.png" alt="Client Design" />
+</div>
+
+### `Storage` trait
+
+This trait declares APIs for different database operations such as `clear`, `get`, `set`, `contains_key`, etc. This 
+crate provides a default implementation (`SledStorage`) of this trait using `Sled` embedded database.
+
+### `SecureStorage` trait
+
+This trait exposes APIs for securely getting and setting values in `Storage`. This crates is automatically implemented
+for all the types implementing `Storage` trait.
+
+### `Chain` trait
+
+This trait exposes APIs for communicating with Crypto.com Chain via ABCI. Currently, this crate exposes following APIs:
+- `query_transaction_changes`: Queries Crypto.com chain for balance changes for different `addresses` from
+  `last_block_height`.
+
+### Services
+
+`Storage` implementation provide generic APIs over any storage backend. In order to provide intended public interface
+(`Wallet`) through this crate, we need specific services for handling storage of different entities, like, keys, 
+wallets, balance, and transactions.
+
+#### `KeyService`
+
+`KeyService` exposes key related operations (`generate` and `get_keys`) on top of any `Storage` implementation.
+- `generate`: Generates a new private key for given `wallet_id` and encrypts it with given `passphrase` before storing.
+- `get_keys`: Returns all the keys stored for given `wallet_id` and decrypts them with given `passphrase`.
+
+#### `WalletService`
+
+`WalletService` exposes wallet related operations (`create` and `get`) on top of any `Storage` implementation.
+- `create`: Creates a new wallet and returns `wallet_id`. This function also encrypts all the data using `passphrase`
+   before storing it in `Storage`.
+- `get`: Retrieves a `wallet_id` from `Storage` and decrypts it with given `passphrase`.
+
+#### `BalanceService`
+
+`BalanceService` exposes balance related operations (`sync`, `sync_all` and `get_balance`) on top of any `Storage` and
+`Chain` implementation.
+- `sync`: Updates balance for given `wallet_id` and `addresses` after querying new transactions from Crypto.com Chain. 
+  This function first retrieves current `balance` and `last_block_height` from `Storage` and then queries `Chain` for 
+  any updates since `last_block_height`. After successful query, it updates the data in `Storage`.
+- `sync_all`: This works in similar way as `sync` except it sets `last_block_height = 0` and queries for all the
+  transactions since genesis block.
+- `get_balance`: Returns balance for a given `wallet_id` from `Storage`.
+
+### `Wallet` trait
+
+Crypto.com exposes public interface through `Wallet` trait which contains following functions with default 
+implementations: 
+
+- `new_wallet`: Creates a new wallet with given `name` and encrypts it with given `passphrase`. This function internally
+  calls `crate` function of `WalletService`. 
+- `get_public_keys`: Retrieves all public keys corresponding to given wallet `name` and `passphrase`. This function
+  internally uses `KeyService` for get this information.
+- `get_addresses`: Retrieves all addresses corresponding to given wallet `name` and `passphrase`. This function 
+  internally uses `KeyService` for get this information.
+- `generate_public_key`: Generates a new public key for given wallet `name` and `passphrase`. This function internally
+  uses `KeyService`.
+- `generate_address`: Generates a new address (redeem) for given wallet `name` and `passphrase`. This function 
+  internally uses `KeyService`.
+- `get_balance`: Retrieves current balance for given wallet `name` and `passphrase`. This function internally uses
+  `BalanceService` to get the balance.
+- `sync_balance`: Synchronizes and returns current balance for given wallet `name` and `passphrase`. This function
+  internally uses `BalanceService::sync` to synchronize balance.
+- `recalculate_balance`: Recalculate current balance for given wallet `name` and `passphrase` from genesis. This 
+  function internally uses `BalanceService::sync_all` to synchronize balance.
+
+## API Documentation
+
+To see this crate's API docs. Run following command from `chain` directory.
+```
+cargo doc --package client-core --no-deps --open
+```
+
+### Warning
+
+This is a work-in-progress crate and is unusable in its current state. These is no implementation for Chain ABCI client
+(`Chain` trait) as of now.

client-core/src/balance.rs

@@ -0,0 +1,6 @@
+//! Types for tracking balance changes
+mod balance_change;
+mod transaction_change;
+
+pub use self::balance_change::BalanceChange;
+pub use self::transaction_change::TransactionChange;

client-core/src/balance/balance_change.rs

@@ -0,0 +1,85 @@
+use std::ops::Add;
+
+use failure::ResultExt;
+
+use crate::{ErrorKind, Result};
+
+use chain_core::init::coin::Coin;
+
+/// Incoming or Outgoing balance change
+#[derive(Debug)]
+pub enum BalanceChange {
+    /// Represents balance addition
+    Incoming(Coin),
+    /// Represents balance reduction
+    Outgoing(Coin),
+}
+
+#[allow(clippy::suspicious_arithmetic_impl)]
+impl Add<&BalanceChange> for Coin {
+    type Output = Result<Coin>;
+
+    fn add(self, other: &BalanceChange) -> Self::Output {
+        match other {
+            BalanceChange::Incoming(change) => {
+                Ok((self + change).context(ErrorKind::BalanceAdditionError)?)
+            }
+            BalanceChange::Outgoing(change) => {
+                Ok((self - change).context(ErrorKind::BalanceAdditionError)?)
+            }
+        }
+    }
+}
+
+impl Add<BalanceChange> for Coin {
+    type Output = Result<Coin>;
+
+    fn add(self, other: BalanceChange) -> Self::Output {
+        self + &other
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn add_incoming() {
+        let coin = Coin::zero()
+            + BalanceChange::Incoming(Coin::new(30).expect("Unable to create new coin"));
+
+        assert_eq!(
+            Coin::new(30).expect("Unable to create new coin"),
+            coin.expect("Unable to add coins"),
+            "Coins does not match"
+        );
+    }
+
+    #[test]
+    fn add_incoming_fail() {
+        let coin = Coin::max()
+            + BalanceChange::Incoming(Coin::new(30).expect("Unable to create new coin"));
+
+        assert!(coin.is_err(), "Created coin greater than max value")
+    }
+
+    #[test]
+    fn add_outgoing() {
+        let coin = Coin::new(40).expect("Unable to create new coin")
+            + BalanceChange::Outgoing(Coin::new(30).expect("Unable to create new coin"));
+
+        assert_eq!(
+            Coin::new(10).expect("Unable to create new coin"),
+            coin.expect("Unable to add coins"),
+            "Coins does not match"
+        );
+    }
+
+    #[test]
+    fn add_outgoing_fail() {
+        let coin = Coin::zero()
+            + BalanceChange::Outgoing(Coin::new(30).expect("Unable to create new coin"));
+
+        assert!(coin.is_err(), "Created negative coin")
+    }
+}

client-core/src/balance/transaction_change.rs

@@ -0,0 +1,97 @@
+use std::ops::Add;
+
+use crate::balance::BalanceChange;
+use crate::Result;
+
+use chain_core::init::coin::Coin;
+use chain_core::tx::data::address::ExtendedAddr;
+use chain_core::tx::data::TxId;
+
+/// Represents balance change in a transaction
+#[derive(Debug)]
+pub struct TransactionChange {
+    /// ID of transaction which caused this change
+    pub transaction_id: TxId,
+    /// Address which is affected by this change
+    pub address: ExtendedAddr,
+    /// Change in balance
+    pub balance_change: BalanceChange,
+}
+
+impl Add<&TransactionChange> for Coin {
+    type Output = Result<Coin>;
+
+    fn add(self, other: &TransactionChange) -> Self::Output {
+        self + &other.balance_change
+    }
+}
+
+impl Add<TransactionChange> for Coin {
+    type Output = Result<Coin>;
+
+    fn add(self, other: TransactionChange) -> Self::Output {
+        self + &other
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use chain_core::tx::data::txid_hash;
+
+    fn get_transaction_change(balance_change: BalanceChange) -> TransactionChange {
+        TransactionChange {
+            transaction_id: txid_hash(&[0, 1, 2]),
+            address: ExtendedAddr::BasicRedeem(Default::default()),
+            balance_change,
+        }
+    }
+
+    #[test]
+    fn add_incoming() {
+        let coin = Coin::zero()
+            + get_transaction_change(BalanceChange::Incoming(
+                Coin::new(30).expect("Unable to create new coin"),
+            ));
+
+        assert_eq!(
+            Coin::new(30).expect("Unable to create new coin"),
+            coin.expect("Unable to add coins"),
+            "Coins does not match"
+        );
+    }
+
+    #[test]
+    fn add_incoming_fail() {
+        let coin = Coin::max()
+            + get_transaction_change(BalanceChange::Incoming(
+                Coin::new(30).expect("Unable to create new coin"),
+            ));
+
+        assert!(coin.is_err(), "Created coin greater than max value")
+    }
+
+    #[test]
+    fn add_outgoing() {
+        let coin = Coin::new(40).expect("Unable to create new coin")
+            + get_transaction_change(BalanceChange::Outgoing(
+                Coin::new(30).expect("Unable to create new coin"),
+            ));
+
+        assert_eq!(
+            Coin::new(10).expect("Unable to create new coin"),
+            coin.expect("Unable to add coins"),
+            "Coins does not match"
+        );
+    }
+
+    #[test]
+    fn add_outgoing_fail() {
+        let coin = Coin::zero()
+            + get_transaction_change(BalanceChange::Outgoing(
+                Coin::new(30).expect("Unable to create new coin"),
+            ));
+
+        assert!(coin.is_err(), "Created negative coin")
+    }
+}

client-core/src/chain.rs

@@ -0,0 +1,23 @@
+//! Communication between client and chain
+
+#[cfg(test)]
+mod mock_chain;
+
+#[cfg(test)]
+pub use mock_chain::MockChain;
+
+use crate::balance::TransactionChange;
+use crate::Result;
+
+/// Interface for a backend agnostic communication between client and chain
+///
+/// ### Warning
+/// This is a WIP trait and will change in future based on requirements.
+pub trait Chain {
+    /// Queries Crypto.com chain for changes for different `addresses` from `last_block_height`
+    fn query_transaction_changes(
+        &self,
+        addresses: Vec<String>,
+        last_block_height: u64,
+    ) -> Result<(Vec<TransactionChange>, u64)>;
+}

client-core/src/chain/mock_chain.rs

@@ -0,0 +1,18 @@
+#![cfg(test)]
+
+use crate::balance::TransactionChange;
+use crate::{Chain, Result};
+
+/// A mock chain client
+#[derive(Clone, Default)]
+pub struct MockChain;
+
+impl Chain for MockChain {
+    fn query_transaction_changes(
+        &self,
+        _addresses: Vec<String>,
+        _last_block_height: u64,
+    ) -> Result<(Vec<TransactionChange>, u64)> {
+        Ok((Default::default(), Default::default()))
+    }
+}

client-core/src/error.rs

@@ -47,6 +47,12 @@ pub enum ErrorKind {
     /// Error while locking a shared resource
     #[fail(display = "Error while locking a shared resource")]
     LockError,
+    /// Error while adding two balances
+    #[fail(display = "Error while adding two balances")]
+    BalanceAdditionError,
+    /// Balance not found
+    #[fail(display = "Balance not found")]
+    BalanceNotFound,
 }
 
 impl Fail for Error {

client-core/src/lib.rs

@@ -4,9 +4,9 @@
 //! This crate exposes following functionalities for interacting with Crypto.com Chain:
 //! - Wallet creation
 //! - Address generation
-//! - Transaction creation and signing
 //! - Transaction syncing and storage
 //! - Balance tracking
+//! - Transaction creation and signing
 //!
 //! ## Features
 //!
@@ -16,12 +16,20 @@
 //!   - Implementation of [`Wallet`](crate::Wallet) trait using [`SledStorage`](crate::storage::SledStorage)
 //!   - Enable with **`"sled"`** feature flag.
 //!   - This feature is enabled by **default**.
+//!
+//! ### Warning
+//!
+//! This is a work-in-progress crate and is unusable in its current state.
+pub mod balance;
+pub mod chain;
 pub mod error;
 pub mod key;
 pub mod service;
 pub mod storage;
 pub mod wallet;
 
+#[doc(inline)]
+pub use chain::Chain;
 #[doc(inline)]
 pub use error::{Error, ErrorKind, Result};
 #[doc(inline)]