@eristack/tax/dist/index.js

Tax code registry and effective-dated rates — math via @eristack/money Tax ops

// src/core/errors.ts
var TaxCodeNotFoundError = class extends Error {
  constructor(code) {
    super(`Tax code not registered: ${code}`);
    this.code = code;
    this.name = "TaxCodeNotFoundError";
  }
  code;
};
var TaxRateNotFoundError = class extends Error {
  constructor(code, asOf) {
    super(`No tax rate for code ${code} effective on or before ${asOf}`);
    this.code = code;
    this.asOf = asOf;
    this.name = "TaxRateNotFoundError";
  }
  code;
  asOf;
};

// src/core/registry.ts
import { Tax } from "@eristack/money";
function normalizeWallDate(date) {
  const trimmed = date.trim();
  if (!/^\d{4}-\d{2}-\d{2}$/.test(trimmed)) {
    throw new Error(`Tax asOf must be wall date YYYY-MM-DD, got "${date}"`);
  }
  return trimmed;
}
function createTaxRegistry(initial) {
  const codes = /* @__PURE__ */ new Map();
  const schedules = [];
  function registerTaxCode(entry) {
    const code = entry.code.trim();
    if (!code) throw new Error("Tax code cannot be empty");
    codes.set(code, { ...entry, code });
  }
  function registerRateSchedule(entry) {
    const code = entry.code.trim();
    if (!codes.has(code)) {
      throw new TaxCodeNotFoundError(code);
    }
    schedules.push({
      ...entry,
      code,
      effectiveFrom: normalizeWallDate(entry.effectiveFrom),
      ratePercent: entry.ratePercent.trim()
    });
    schedules.sort((a, b) => {
      const byCode = a.code.localeCompare(b.code);
      if (byCode !== 0) return byCode;
      return a.effectiveFrom.localeCompare(b.effectiveFrom);
    });
  }
  for (const c of initial?.codes ?? []) registerTaxCode(c);
  for (const r of initial?.rates ?? []) registerRateSchedule(r);
  function resolveTaxRate(args) {
    const code = args.code.trim();
    if (!codes.has(code)) {
      throw new TaxCodeNotFoundError(code);
    }
    const asOf = normalizeWallDate(args.asOf);
    let match;
    for (const row of schedules) {
      if (row.code !== code) continue;
      if (row.effectiveFrom <= asOf) {
        match = row;
      } else if (match) {
        break;
      }
    }
    if (!match) {
      throw new TaxRateNotFoundError(code, asOf);
    }
    return {
      code: match.code,
      effectiveFrom: match.effectiveFrom,
      ratePercent: match.ratePercent
    };
  }
  function applyTaxToAmount(base, ratePercent) {
    return base.with(Tax.onExclusive(ratePercent));
  }
  function listTaxCodes() {
    return [...codes.values()];
  }
  return {
    registerTaxCode,
    registerRateSchedule,
    resolveTaxRate,
    applyTaxToAmount,
    listTaxCodes
  };
}
export {
  TaxCodeNotFoundError,
  TaxRateNotFoundError,
  createTaxRegistry
};
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