Initial import of just-about-working version

src/transaction.rs

@@ -0,0 +1,49 @@
+pub struct Transaction {
+    pub date: String,
+    pub payee: String,
+    pub amount: i64,
+}
+
+fn parse_amount_str(amount: &str) -> Result<i64, String> {
+    if amount.is_empty() {
+        return Err("empty amount".to_string());
+    }
+    let (whole, frac) = amount.split_once('.').unwrap_or((amount, "00"));
+    let whole = whole
+        .parse::<i64>()
+        .map_err(|e| format!("parse error on whole {}: {}", whole, e))?;
+    let frac = frac
+        .parse::<i64>()
+        .map_err(|e| format!("parse error on fraction {}: {}", frac, e))?;
+
+    let mut amount: i64 = 0;
+    amount += whole * 100 * 10;
+    amount += if whole < 0 { -frac } else { frac } * 10;
+    Ok(amount)
+}
+
+impl Transaction {
+    /// Construct a Transaction from [date, payee, amount] strings
+    pub fn from_fields(date: &str, payee: &str, amount: &str) -> Result<Transaction, String> {
+        Ok(Transaction {
+            date: date.to_owned(),
+            payee: payee.to_owned(),
+            amount: parse_amount_str(amount)?,
+        })
+    }
+
+    fn format_amount(&self) -> String {
+        let whole = self.amount / 10 / 100;
+        let frac = if self.amount < 0 { -1 } else { 1 } * (self.amount / 10) % 100;
+        format!("{}.{:02}", whole, frac)
+    }
+
+    pub fn to_record(&self) -> [String; 4] {
+        [
+            self.date.to_string(),
+            self.payee.to_string(),
+            String::new(),
+            self.format_amount(),
+        ]
+    }
+}