fix: add display_currency_decimal method (tari-project#3445)

Description
---
The inner type of `Tari` changed from `f64` to `decimal_rs::Decimal`.
Also, `display_currency` method was replaced with `format_currency` that adds separators to formatted strings.

Motivation and Context
---
`display_currency` method forces us to use `f64` that is not accurate for finance calculations.

How Has This Been Tested?
---
Updated unit tests.
**TODO:** Smoke test: run the wallet and the node.

applications/tari_console_wallet/src/automation/commands.rs

@@ -23,6 +23,7 @@
 use super::error::CommandError;
 use log::*;
 use std::{
+    convert::TryFrom,
     fs::File,
     io::{LineWriter, Write},
     str::FromStr,
@@ -661,7 +662,7 @@ pub async fn command_runner(
                 }
                 if count > 0 {
                     let average = f64::from(sum) / count as f64;
-                    let average = Tari::from(average / 1_000_000f64);
+                    let average = Tari::try_from(average / 1_000_000f64)?;
                     println!("Average value UTXO   : {}", average);
                 }
                 if let Some(max) = values.iter().max() {

applications/tari_console_wallet/src/automation/error.rs

@@ -25,7 +25,10 @@ use std::num::{ParseFloatError, ParseIntError};
 use chrono_english::DateError;
 use log::*;
 use tari_app_utilities::utilities::ExitCodes;
-use tari_core::transactions::{tari_amount::MicroTariError, transaction::TransactionError};
+use tari_core::transactions::{
+    tari_amount::{MicroTariError, TariConversionError},
+    transaction::TransactionError,
+};
 use tari_wallet::{
     error::{WalletError, WalletStorageError},
     output_manager_service::error::OutputManagerError,
@@ -41,6 +44,8 @@ pub const LOG_TARGET: &str = "wallet::automation::error";
 pub enum CommandError {
     #[error("Argument error - were they in the right order?")]
     Argument,
+    #[error("Tari value conversion error `{0}`")]
+    TariConversionError(#[from] TariConversionError),
     #[error("Transaction service error `{0}`")]
     TransactionError(#[from] TransactionError),
     #[error("Transaction service error `{0}`")]

base_layer/core/Cargo.toml

@@ -39,6 +39,7 @@ sha3 = "0.9"
 bytes = "0.5"
 chrono = { version = "0.4.6", features = ["serde"] }
 croaring = { version = "=0.4.5", optional = true }
+decimal-rs = "0.1.20"
 digest = "0.9.0"
 futures = { version = "^0.3.16", features = ["async-await"] }
 fs2 = "0.3.0"
@@ -64,6 +65,7 @@ num-format = "0.4.0"
 tracing = "0.1.26"
 tracing-futures = "*"
 tracing-attributes = "*"
+derive_more = "0.99.16"
 
 [dev-dependencies]
 tari_p2p = { version = "^0.11", path = "../../base_layer/p2p", features = ["test-mocks"] }

base_layer/core/src/transactions/helpers.rs

@@ -22,7 +22,6 @@
 
 use std::sync::Arc;
 
-use num::pow;
 use rand::rngs::OsRng;
 use tari_crypto::{
     commitment::HomomorphicCommitmentFactory,
@@ -565,51 +564,44 @@ pub fn schema_to_transaction(txns: &[TransactionSchema]) -> (Vec<Arc<Transaction
 /// # Examples
 ///
 /// ```
-/// use tari_core::transactions::helpers::display_currency;
-/// assert_eq!(String::from("12,345.12"), display_currency(12345.12, 2, ","));
-/// assert_eq!(String::from("12,345"), display_currency(12345.12, 0, ","));
+/// use tari_core::transactions::helpers::format_currency;
+/// assert_eq!("12,345.12", format_currency("12345.12", ','));
+/// assert_eq!("12,345", format_currency("12345", ','));
 /// ```
-pub fn display_currency(value: f64, precision: usize, separator: &str) -> String {
-    let whole = value as usize;
-    let decimal = ((value - whole as f64) * pow(10_f64, precision)).round() as usize;
-    let formatted_whole_value = whole
-        .to_string()
-        .chars()
-        .rev()
-        .enumerate()
-        .fold(String::new(), |acc, (i, c)| {
-            if i != 0 && i % 3 == 0 {
-                format!("{}{}{}", acc, separator, c)
-            } else {
-                format!("{}{}", acc, c)
-            }
-        })
-        .chars()
-        .rev()
-        .collect::<String>();
-
-    if precision > 0 {
-        format!("{}.{:0>2$}", formatted_whole_value, decimal, precision)
-    } else {
-        formatted_whole_value
+pub fn format_currency(value: &str, separator: char) -> String {
+    let full_len = value.len();
+    let mut buffer = String::with_capacity(full_len / 3 + full_len);
+    let mut iter = value.splitn(2, '.');
+    let whole = iter.next().unwrap_or("");
+    let mut idx = whole.len() as isize - 1;
+    for c in whole.chars() {
+        buffer.push(c);
+        if idx > 0 && idx % 3 == 0 {
+            buffer.push(separator);
+        }
+        idx -= 1;
     }
+    if let Some(decimal) = iter.next() {
+        buffer.push('.');
+        buffer.push_str(decimal);
+    }
+    buffer
 }
 
 #[cfg(test)]
 #[allow(clippy::excessive_precision)]
 mod test {
+    use super::format_currency;
+
     #[test]
-    fn display_currency() {
-        assert_eq!(String::from("0.00"), super::display_currency(0.0f64, 2, ","));
-        assert_eq!(String::from("0.000000000000"), super::display_currency(0.0f64, 12, ","));
-        assert_eq!(
-            String::from("123,456.123456789"),
-            super::display_currency(123_456.123_456_789_012_f64, 9, ",")
-        );
-        assert_eq!(
-            String::from("123,456"),
-            super::display_currency(123_456.123_456_789_012_f64, 0, ",")
-        );
-        assert_eq!(String::from("1,234"), super::display_currency(1234.1f64, 0, ","));
+    fn test_format_currency() {
+        assert_eq!("0.00", format_currency("0.00", ','));
+        assert_eq!("0.000000000000", format_currency("0.000000000000", ','));
+        assert_eq!("123,456.123456789", format_currency("123456.123456789", ','));
+        assert_eq!("123,456", format_currency("123456", ','));
+        assert_eq!("123", format_currency("123", ','));
+        assert_eq!("7,123", format_currency("7123", ','));
+        assert_eq!(".00", format_currency(".00", ','));
+        assert_eq!("00.", format_currency("00.", ','));
     }
 }