feat(WHE-18): implement money, billing period, and typed domain ids

packages/domain/src/billing-period.ts

@@ -0,0 +1,98 @@
+import { DOMAIN_ERROR_CODE, DomainError } from './errors'
+
+const BILLING_PERIOD_PATTERN = /^(\d{4})-(\d{2})$/
+
+function isIntegerInRange(value: number, min: number, max: number): boolean {
+  return Number.isInteger(value) && value >= min && value <= max
+}
+
+export class BillingPeriod {
+  readonly year: number
+  readonly month: number
+
+  private constructor(year: number, month: number) {
+    this.year = year
+    this.month = month
+  }
+
+  static from(year: number, month: number): BillingPeriod {
+    if (!isIntegerInRange(year, 1970, 9999)) {
+      throw new DomainError(
+        DOMAIN_ERROR_CODE.INVALID_BILLING_PERIOD,
+        `Invalid billing year: ${year}`
+      )
+    }
+
+    if (!isIntegerInRange(month, 1, 12)) {
+      throw new DomainError(
+        DOMAIN_ERROR_CODE.INVALID_BILLING_PERIOD,
+        `Invalid billing month: ${month}`
+      )
+    }
+
+    return new BillingPeriod(year, month)
+  }
+
+  static fromString(value: string): BillingPeriod {
+    const match = BILLING_PERIOD_PATTERN.exec(value)
+
+    if (!match) {
+      throw new DomainError(
+        DOMAIN_ERROR_CODE.INVALID_BILLING_PERIOD,
+        `Billing period must match YYYY-MM: ${value}`
+      )
+    }
+
+    const [, yearString, monthString] = match
+
+    return BillingPeriod.from(Number(yearString), Number(monthString))
+  }
+
+  static fromDate(date: Date): BillingPeriod {
+    return BillingPeriod.from(date.getUTCFullYear(), date.getUTCMonth() + 1)
+  }
+
+  next(): BillingPeriod {
+    if (this.month === 12) {
+      return BillingPeriod.from(this.year + 1, 1)
+    }
+
+    return BillingPeriod.from(this.year, this.month + 1)
+  }
+
+  previous(): BillingPeriod {
+    if (this.month === 1) {
+      return BillingPeriod.from(this.year - 1, 12)
+    }
+
+    return BillingPeriod.from(this.year, this.month - 1)
+  }
+
+  compare(other: BillingPeriod): -1 | 0 | 1 {
+    if (this.year < other.year) {
+      return -1
+    }
+
+    if (this.year > other.year) {
+      return 1
+    }
+
+    if (this.month < other.month) {
+      return -1
+    }
+
+    if (this.month > other.month) {
+      return 1
+    }
+
+    return 0
+  }
+
+  equals(other: BillingPeriod): boolean {
+    return this.year === other.year && this.month === other.month
+  }
+
+  toString(): string {
+    return `${this.year.toString().padStart(4, '0')}-${this.month.toString().padStart(2, '0')}`
+  }
+}