1 files changed, 61 insertions, 0 deletions
diff --git a/web/src/math/Ratio.ts b/web/src/math/Ratio.ts
new file mode 100644
index 0000000..4973ff4
--- /dev/null
+++ b/web/src/math/Ratio.ts
@@ -0,0 +1,61 @@
+/** Serializable representation of a ratio. */
+export type RatioData = [numerator: number, denominator: number];
+
+/** Representation of a ratio for performing fractional artithmetic. */
+export default class Ratio {
+  private readonly _numerator: number;
+  private readonly _denominator: number;
+
+  get numerator(): number {
+    return this._numerator;
+  }
+
+  get denominator(): number {
+    return this._denominator;
+  }
+
+  constructor(numerator: number, denominator: number) {
+    if (!Number.isInteger(numerator) || !Number.isInteger(denominator)) {
+      throw new TypeError(
+        `Ratio must have integer parts: ${numerator} / ${denominator}`,
+      );
+    }
+
+    if (denominator === 0) {
+      throw new RangeError("Ratio demnominator cannot be zero");
+    }
+
+    this._numerator = numerator;
+    this._denominator = denominator;
+  }
+
+  multiplyRatio(other: Ratio): Ratio {
+    return new Ratio(
+      this.numerator * other.numerator,
+      this.denominator * other.denominator,
+    );
+  }
+
+  divideRatio(other: Ratio): Ratio {
+    return new Ratio(
+      this.numerator * other.denominator,
+      this.denominator * other.numerator,
+    );
+  }
+
+  toNumber(): number {
+    return this.numerator / this.denominator;
+  }
+
+  static fromInteger(n: number): Ratio {
+    return new Ratio(n, 1);
+  }
+
+  toData(): RatioData {
+    return [this.numerator, this.denominator];
+  }
+
+  static fromData(ratio: RatioData): Ratio {
+    return new Ratio(ratio[0], ratio[1]);
+  }
+}