WIP

2026-06-20 17:51:33 -07:00
parent f55807fa7d
commit 3558c67fd7
55 changed files with 3140 additions and 85 deletions
@@ -0,0 +1,75 @@
+namespace ROLAC.API.Services.Disbursement;
+
+/// <summary>
+/// Converts a monetary amount to the English words used on a check, e.g.
+/// 1234.56 → "One Thousand Two Hundred Thirty-Four and 56/100 Dollars".
+/// Pure and dependency-free so it is easily unit-tested.
+/// </summary>
+public static class AmountToWords
+{
+    private static readonly string[] Ones =
+    [
+        "Zero", "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine",
+        "Ten", "Eleven", "Twelve", "Thirteen", "Fourteen", "Fifteen", "Sixteen",
+        "Seventeen", "Eighteen", "Nineteen",
+    ];
+
+    private static readonly string[] Tens =
+    [
+        "", "", "Twenty", "Thirty", "Forty", "Fifty", "Sixty", "Seventy", "Eighty", "Ninety",
+    ];
+
+    // index 1.. → 10^(3*index)
+    private static readonly string[] Scales = ["", "Thousand", "Million", "Billion", "Trillion"];
+
+    public static string Convert(decimal amount)
+    {
+        if (amount < 0) amount = 0m;
+        // Round half-up to cents.
+        amount = Math.Round(amount, 2, MidpointRounding.AwayFromZero);
+
+        var dollars = (long)Math.Floor(amount);
+        var cents   = (int)Math.Round((amount - dollars) * 100m, MidpointRounding.AwayFromZero);
+
+        var words = dollars == 0 ? "Zero" : ThreeDigitGroupsToWords(dollars);
+        return $"{words} and {cents:00}/100 Dollars";
+    }
+
+    private static string ThreeDigitGroupsToWords(long n)
+    {
+        // Split into groups of three digits, low to high.
+        var groups = new List<int>();
+        while (n > 0) { groups.Add((int)(n % 1000)); n /= 1000; }
+
+        var parts = new List<string>();
+        for (var i = groups.Count - 1; i >= 0; i--)
+        {
+            if (groups[i] == 0) continue;
+            var group = HundredsToWords(groups[i]);
+            var scale = Scales[i];
+            parts.Add(string.IsNullOrEmpty(scale) ? group : $"{group} {scale}");
+        }
+        return string.Join(" ", parts);
+    }
+
+    private static string HundredsToWords(int n)
+    {
+        var parts = new List<string>();
+        if (n >= 100)
+        {
+            parts.Add($"{Ones[n / 100]} Hundred");
+            n %= 100;
+        }
+        if (n >= 20)
+        {
+            var t = Tens[n / 10];
+            var o = n % 10;
+            parts.Add(o == 0 ? t : $"{t}-{Ones[o]}");
+        }
+        else if (n > 0)
+        {
+            parts.Add(Ones[n]);
+        }
+        return string.Join(" ", parts);
+    }
+}