/**
 * AAMOS Bank CSV Import Service
 * E1-003
 * Port: 3252
 *
 * Importerar banktransaktioner (CSV) från svenska banker och skapar
 * draft journal entries i Ledger Engine (port 3250).
 */

import express from 'express';
import cors    from 'cors';
import { randomUUID } from 'crypto';
import { parseCSV, detectBank, SUPPORTED_FORMATS } from './parsers.mjs';

const PORT        = parseInt(process.env.PORT || '3252', 10);
const LEDGER_BASE = process.env.LEDGER_URL || 'http://127.0.0.1:3250';

const app = express();
app.use(cors());
app.use(express.json({ limit: '20mb' }));

// ── Health ────────────────────────────────────────────────────────────────────

app.get('/health', (_req, res) => {
  res.json({ ok: true, service: 'aamos-bank-import', port: PORT, ledger: LEDGER_BASE });
});

// ── GET /api/bank/formats ─────────────────────────────────────────────────────

app.get('/api/bank/formats', (_req, res) => {
  res.json({ ok: true, formats: SUPPORTED_FORMATS });
});

// ── POST /api/bank/import ─────────────────────────────────────────────────────

app.post('/api/bank/import', async (req, res) => {
  const {
    bank          = 'auto',
    csv_content,
    account_number = '1910',
    tenant_id,
    dry_run        = false,
    debit_account_positive  = '3000', // kredit vid positiva belopp (inkomst)
    credit_account_negative = '4000', // debet vid negativa belopp (utgift)
  } = req.body ?? {};

  if (!csv_content || typeof csv_content !== 'string') {
    return res.status(400).json({ ok: false, error: 'csv_content (string) krävs' });
  }

  const correlation_id = randomUUID();
  const trace_id       = randomUUID();
  const resolved_tenant = tenant_id || req.headers['x-tenant-id'] || 'wavult-group';

  // ── Parse CSV ──────────────────────────────────────────────────────────────
  let parsed;
  let resolvedBank;
  try {
    parsed = parseCSV(bank, csv_content);
    resolvedBank = parsed.bank;
  } catch (err) {
    return res.status(400).json({
      ok: false,
      error: `CSV parse-fel: ${err.message}`,
      correlation_id,
      trace_id,
    });
  }

  const rows = parsed.rows;
  const rows_parsed = rows.length;

  if (rows_parsed === 0) {
    return res.json({
      ok: true,
      bank: resolvedBank,
      rows_parsed: 0,
      rows_imported: 0,
      skipped: 0,
      errors: [],
      correlation_id,
      trace_id,
      dry_run,
    });
  }

  // ── Dry run — returnera utan att importera ─────────────────────────────────
  if (dry_run) {
    return res.json({
      ok: true,
      dry_run: true,
      bank: resolvedBank,
      rows_parsed,
      rows_imported: 0,
      skipped: 0,
      errors: [],
      preview: rows.slice(0, 5),
      correlation_id,
      trace_id,
    });
  }

  // ── Live import — posta varje rad som en journal entry ─────────────────────
  let rows_imported = 0;
  let skipped = 0;
  const errors = [];

  for (const row of rows) {
    try {
      // Validera datum
      if (!row.date || !/^\d{4}-\d{2}-\d{2}/.test(row.date)) {
        skipped++;
        errors.push({ row: row.raw, reason: `Ogiltigt datum: "${row.date}"` });
        continue;
      }

      const amount = row.amount;
      if (amount == null || amount === 0) {
        skipped++;
        errors.push({ row: row.raw, reason: 'Belopp är noll eller saknas' });
        continue;
      }

      const absAmount = Math.abs(amount).toFixed(2);

      /*
       * Positiva belopp (inkomst/insättning):
       *   Debet: 1910 (bank), Kredit: 3000 (intäkt)
       *
       * Negativa belopp (utgift/uttag):
       *   Debet: 4000 (kostnad), Kredit: 1910 (bank)
       *
       * Ledger kräver ANTINGEN debit ELLER credit per rad (ej båda).
       */
      let lines;
      if (amount > 0) {
        lines = [
          { account_number: account_number,          debit:  absAmount, description: row.description },
          { account_number: debit_account_positive,  credit: absAmount, description: row.description },
        ];
      } else {
        lines = [
          { account_number: credit_account_negative, debit:  absAmount, description: row.description },
          { account_number: account_number,          credit: absAmount, description: row.description },
        ];
      }

      // Extrahera period från datum (YYYY-MM)
      const entryDate = row.date.substring(0, 10);
      const fy        = entryDate.substring(0, 4);
      const period    = entryDate.substring(0, 7);

      const body = {
        entry_date:   entryDate,
        description:  row.description || `Banktransaktion ${entryDate}`,
        reference:    row.raw?.substring(0, 200),
        source_type:  'import_csv',
        source_id:    `${resolvedBank}:${correlation_id}:${rows_imported + skipped}`,
        lines,
        period,
        fiscal_year:  parseInt(fy, 10),
        metadata: {
          bank:           resolvedBank,
          original_amount: amount,
          balance:        row.balance,
          correlation_id,
          import_service: 'aamos-bank-import',
        },
      };

      const response = await fetch(`${LEDGER_BASE}/api/ledger/journal`, {
        method:  'POST',
        headers: {
          'Content-Type':  'application/json',
          'X-Trace-Id':    trace_id,
          'X-User-Id':     'bank-import',
          'X-Tenant-Id':   resolved_tenant,
          'X-Correlation-Id': correlation_id,
        },
        body: JSON.stringify(body),
      });

      const result = await response.json();

      if (!response.ok || !result.ok) {
        skipped++;
        errors.push({
          row:    row.raw,
          reason: result.error || `HTTP ${response.status}`,
          details: result,
        });
      } else {
        rows_imported++;
      }
    } catch (err) {
      skipped++;
      errors.push({ row: row.raw, reason: err.message });
    }
  }

  res.json({
    ok: true,
    bank:          resolvedBank,
    rows_parsed,
    rows_imported,
    skipped,
    errors:        errors.slice(0, 50), // max 50 errors i svaret
    correlation_id,
    trace_id,
    dry_run: false,
  });
});

// ── Start ─────────────────────────────────────────────────────────────────────

app.listen(PORT, () => {
  console.log(`[aamos-bank-import] Lyssnar på port ${PORT}`);
  console.log(`[aamos-bank-import] Ledger Engine: ${LEDGER_BASE}`);
});