判定優先順位:
1. taxCategoryBase に「返還」を含む -> credit-note
2. 全エントリが「対象外」 -> none（決算整理仕訳）
3. problem に「委託販売」「売上計算書」 -> sales-statement
4. problem に「現金で」 -> receipt
5. その他 -> invoice

apps/web/app/
  utils/
    voucher-types.ts          # 共通型定義
    voucher-mapper.ts         # データ変換ロジック
  components/voucher/
    InvoiceTemplate.vue       # 請求書（適格請求書）
    ReceiptTemplate.vue       # 領収書（適格簡易請求書）
    CreditNoteTemplate.vue    # 返還請求書（適格返還請求書）
    SalesStatementTemplate.vue # 売上計算書（委託販売）
  pages/tax-patterns/
    voucher-demo.vue          # デモページ（タブ切替・左右分割）

export type VoucherType = 'invoice' | 'receipt' | 'credit-note' | 'sales-statement' | 'none';

export interface VoucherLineItem {
  description: string;
  amount: number;
  taxRate: string;       // "10%" | "8%軽減" | "8%(旧)" etc.
  netAmount: number;     // 税抜金額
  taxAmount: number;     // 消費税額
}

export interface VoucherData {
  type: VoucherType;
  documentNo: string;
  counterparty: string;
  lineItems: VoucherLineItem[];
  totalAmount: number;
  remarks?: string;
}

export function detectVoucherType(example: AccountingExample): VoucherType {
  // 1. 返品・値引き系: カテゴリ名 + 税区分「返還」で判定
  const hasReturn = example.categoryName.includes('値引')
    || example.categoryName.includes('戻し')
    || example.categoryName.includes('戻り')
    || example.patterns.some(p => p.entries.some(e =>
        e.debit.taxCategoryBase.includes('返還')
        || e.credit.taxCategoryBase.includes('返還')
      ));
  if (hasReturn) return 'credit-note';

  // 2. 委託販売
  if (example.problem.includes('委託販売') || example.problem.includes('売上計算書'))
    return 'sales-statement';

  // 3. 現金取引
  if (example.problem.includes('現金で'))
    return 'receipt';

  // 4. 全エントリが「対象外」-> 内部処理（帳票なし）
  const allOutside = example.patterns.every(p =>
    p.entries.every(e =>
      e.debit.taxCategoryBase === '対象外' && e.credit.taxCategoryBase === '対象外'
    )
  );
  if (allOutside) return 'none';

  // 5. デフォルト: 請求書
  return 'invoice';
}

export function calcTaxBreakdown(amount: number, taxRate: string): { net: number; tax: number } {
  // 免税・非課税・不課税は消費税なし
  if (taxRate === '免税' || taxRate === '非課税' || taxRate === '不課税') {
    return { net: amount, tax: 0 };
  }
  const rateNum = taxRate === '8%軽減' || taxRate === '8%(旧)' ? 8 : 10;
  const tax = Math.floor(amount * rateNum / (100 + rateNum));
  return { net: amount - tax, tax };
}

function resolveTaxRate(taxCategoryBase: string, taxRate?: string): string {
  if (taxCategoryBase === '輸出免税売上') return '免税';
  if (taxCategoryBase === '非課税売上') return '非課税';
  if (taxCategoryBase === '不課税売上') return '不課税';
  return taxRate || '10%';
}

const taxSummary = computed(() => {
  const map = new Map<string, { net: number; tax: number; total: number }>();
  props.voucher.lineItems.forEach(item => {
    const existing = map.get(item.taxRate) || { net: 0, tax: 0, total: 0 };
    existing.net += item.netAmount;
    existing.tax += item.taxAmount;
    existing.total += item.amount;
    map.set(item.taxRate, existing);
  });
  return Array.from(map.entries()).sort(([a], [b]) => b.localeCompare(a));
});

const purposeText = computed(() => {
  const names = props.voucher.lineItems.map(i => i.description);
  return names.join('・') + 'として';
});

const typeCounts = computed(() => {
  const counts = new Map<VoucherType, number>();
  allExamples.value.forEach(ex => {
    const type = detectVoucherType(ex);
    counts.set(type, (counts.get(type) || 0) + 1);
  });
  return counts;
});

// 修正前: 浮動小数点除算
const net = Math.floor(amount / (1 + rate));
// 1,650,000 / 1.1 = 1499999.9999... -> Math.floor -> 1,499,999（1円ずれる）

// 修正後: 整数演算で端数回避
const rateNum = taxRate === '8%軽減' || taxRate === '8%(旧)' ? 8 : 10;
const tax = Math.floor(amount * rateNum / (100 + rateNum));
return { net: amount - tax, tax };
// 1,650,000 * 10 / 110 = 150,000（正確）
// net = 1,650,000 - 150,000 = 1,500,000（正確）