/**
 * test/double-entry.test.mjs — Double-entry bookkeeping validation tests
 */
import { describe, it, before } from 'node:test';
import assert from 'node:assert';

// Mock pool for testing
function createMockPool() {
  const queries = [];
  return {
    queries,
    query: async (sql, params) => {
      queries.push({ sql, params });
      // Default responses
      if (sql.includes('SELECT status FROM ledger_periods')) {
        return { rows: [{ status: 'open' }] };
      }
      if (sql.includes('INSERT INTO ledger_journal_entries')) {
        return { rows: [{
          id: 'test-entry-id',
          tenant_id: params[0],
          fiscal_year: params[1],
          period: params[2],
          entry_date: params[3],
          description: params[4],
          status: 'draft'
        }] };
      }
      if (sql.includes('INSERT INTO ledger_journal_lines')) {
        return { rows: [{
          id: 'test-line-id',
          entry_id: params[0],
          line_number: params[2],
          account_number: params[3],
          debit: params[5],
          credit: params[6]
        }] };
      }
      return { rows: [] };
    },
    connect: async () => ({
      query: async (sql, params) => {
        queries.push({ sql, params, client: true });
        if (sql === 'BEGIN') return {};
        if (sql === 'COMMIT') return {};
        if (sql === 'ROLLBACK') return {};
        if (sql.includes('SELECT status FROM ledger_periods')) {
          return { rows: [{ status: 'open' }] };
        }
        if (sql.includes('INSERT INTO ledger_journal_entries')) {
          return { rows: [{
            id: 'test-entry-id',
            tenant_id: params[0],
            fiscal_year: params[1],
            period: params[2],
            entry_date: params[3],
            description: params[4],
            status: 'draft'
          }] };
        }
        if (sql.includes('INSERT INTO ledger_journal_lines')) {
          return { rows: [{
            id: 'test-line-id',
            entry_id: params[0],
            line_number: params[2],
            account_number: params[3],
            debit: params[5],
            credit: params[6]
          }] };
        }
        return { rows: [] };
      },
      release: () => {}
    })
  };
}

// Simple double-entry validation (same logic as in routes)
function validateDoubleEntry(lines) {
  const totalDebit  = lines.reduce((s, l) => s + (parseFloat(l.debit)  || 0), 0);
  const totalCredit = lines.reduce((s, l) => s + (parseFloat(l.credit) || 0), 0);
  return {
    valid: Math.abs(totalDebit - totalCredit) <= 0.01,
    totalDebit,
    totalCredit,
    diff: Math.abs(totalDebit - totalCredit)
  };
}

describe('Double-entry validation', () => {
  it('should accept balanced entries (debit = credit)', () => {
    const lines = [
      { account_number: '1930', debit: 1000, credit: 0 },
      { account_number: '3000', debit: 0, credit: 1000 }
    ];
    const result = validateDoubleEntry(lines);
    assert.strictEqual(result.valid, true);
    assert.strictEqual(result.totalDebit, 1000);
    assert.strictEqual(result.totalCredit, 1000);
  });

  it('should reject unbalanced entries (debit ≠ credit)', () => {
    const lines = [
      { account_number: '1930', debit: 1000, credit: 0 },
      { account_number: '3000', debit: 0, credit: 500 }
    ];
    const result = validateDoubleEntry(lines);
    assert.strictEqual(result.valid, false);
    assert.strictEqual(result.diff, 500);
  });

  it('should handle multiple lines correctly', () => {
    const lines = [
      { account_number: '1930', debit: 1000, credit: 0 },
      { account_number: '2610', debit: 250, credit: 0 },
      { account_number: '3000', debit: 0, credit: 1250 }
    ];
    const result = validateDoubleEntry(lines);
    assert.strictEqual(result.valid, true);
    assert.strictEqual(result.totalDebit, 1250);
    assert.strictEqual(result.totalCredit, 1250);
  });

  it('should handle zero amounts', () => {
    const lines = [
      { account_number: '1930', debit: 0, credit: 0 },
      { account_number: '3000', debit: 0, credit: 0 }
    ];
    const result = validateDoubleEntry(lines);
    assert.strictEqual(result.valid, true);
  });

  it('should handle floating point precision (0.01 tolerance)', () => {
    const lines = [
      { account_number: '1930', debit: 100.005, credit: 0 },
      { account_number: '3000', debit: 0, credit: 100 }
    ];
    const result = validateDoubleEntry(lines);
    assert.strictEqual(result.valid, true); // 0.005 diff is within 0.01 tolerance
  });
});

describe('Line validation', () => {
  it('should require at least 2 lines', () => {
    const lines = [
      { account_number: '1930', debit: 1000, credit: 0 }
    ];
    assert.strictEqual(lines.length < 2, true);
  });

  it('should require account_number on each line', () => {
    const lines = [
      { account_number: '1930', debit: 1000, credit: 0 },
      { account_number: null, debit: 0, credit: 1000 }
    ];
    const hasMissingAccount = lines.some(l => !l.account_number);
    assert.strictEqual(hasMissingAccount, true);
  });

  it('should require exactly one of debit or credit per line', () => {
    const linesBoth = [
      { account_number: '1930', debit: 1000, credit: 500 }
    ];
    const linesNone = [
      { account_number: '1930', debit: null, credit: null }
    ];
    
    const bothInvalid = (l) => (l.debit != null) === (l.credit != null);
    assert.strictEqual(bothInvalid(linesBoth[0]), true);
    assert.strictEqual(bothInvalid(linesNone[0]), true);
  });
});