/**
 * MongoDB-Export → MySQL Migration
 *
 * Liest eine NDJSON-Datei (mongoexport-Format, eine Zeile = ein Dokument)
 * und importiert alle Einträge in die MySQL-Tabelle.
 *
 * Konfiguration via Umgebungsvariablen oder direkt hier eintragen:
 *
 *   IMPORT_FILE    Pfad zur Exportdatei       (default: ~/Downloads/spritzschema_a)
 *   MYSQLHOST      MySQL-Host                 (default: localhost)
 *   MYSQLPORT      MySQL-Port                 (default: 3306)
 *   MYSQLUSER      MySQL-Benutzer             (default: root)
 *   MYSQLPASSWORD  MySQL-Passwort             (default: leer)
 *   MYSQLBASE      MySQL-Datenbank            (default: medizin)
 *   MYSQL_TABLE    MySQL-Tabellenname         (default: spritzschema)
 *
 * Aufruf:
 *   node scripts/migrate-mongo-to-mysql.mjs
 *   IMPORT_FILE=/pfad/zur/datei node scripts/migrate-mongo-to-mysql.mjs
 */

import fs from 'fs';
import os from 'os';
import path from 'path';
import mysql from 'mysql2/promise';

// ── .env.local laden (falls vorhanden) ────────────────────────
const envFile = path.resolve(process.cwd(), '.env.local');
if (fs.existsSync(envFile)) {
  for (const line of fs.readFileSync(envFile, 'utf-8').split('\n')) {
    const m = line.match(/^\s*([A-Z_]+)\s*=\s*(.*)\s*$/);
    if (m && !process.env[m[1]]) process.env[m[1]] = m[2].replace(/^['"]|['"]$/g, '');
  }
}

// ── Konfiguration ──────────────────────────────────────────────
const IMPORT_FILE = process.env.IMPORT_FILE
  || path.join(os.homedir(), 'Downloads', 'spritzschema_a');

const MYSQLHOST      = process.env.MYSQLHOST     || 'localhost';
const MYSQLPORT      = parseInt(process.env.MYSQLPORT || '3306');
const MYSQLUSER      = process.env.MYSQLUSER     || 'root';
const MYSQLPASSWORD  = process.env.MYSQLPASSWORD || '';
const MYSQLBASE      = process.env.MYSQLBASE     || 'medizin';
const MYSQL_TABLE    = process.env.MYSQL_TABLE   || 'spritzschema';
// ───────────────────────────────────────────────────────────────

async function ensureTable(conn) {
  await conn.query(`
    CREATE TABLE IF NOT EXISTS \`${MYSQL_TABLE}\` (
      id INT AUTO_INCREMENT PRIMARY KEY,
      curdate VARCHAR(20) NOT NULL UNIQUE,
      months JSON NOT NULL,
      years JSON NOT NULL,
      data JSON NOT NULL,
      einheit INT NOT NULL DEFAULT 0,
      updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
    )
  `);
}

function normalizeDoc(doc) {
  // einheit in data-Items kann String oder Number sein → immer Int
  const data = (Array.isArray(doc.data) ? doc.data : []).map((item) => ({
    ...item,
    einheit: parseInt(item.einheit) || 0,
  }));
  return {
    curdate: doc.curdate ?? '',
    months:  Array.isArray(doc.months) ? doc.months : [],
    years:   Array.isArray(doc.years)  ? doc.years  : [],
    data,
    einheit: parseInt(doc.einheit) || 0,
  };
}

async function readExportFile(filePath) {
  const content = fs.readFileSync(filePath, 'utf-8').trim();
  // Unterstützt beide Formate: JSON-Array [...] und NDJSON (eine Zeile = ein Dokument)
  if (content.startsWith('[')) {
    return JSON.parse(content);
  }
  // NDJSON-Fallback
  const docs = [];
  let lineNo = 0;
  for (const line of content.split('\n')) {
    lineNo++;
    const trimmed = line.trim();
    if (!trimmed) continue;
    try {
      docs.push(JSON.parse(trimmed));
    } catch (e) {
      console.warn(`  SKIP Zeile ${lineNo}: Kein gültiges JSON (${e.message})`);
    }
  }
  return docs;
}

async function migrate() {
  // ── Exportdatei lesen ──
  console.log(`Lese Exportdatei: ${IMPORT_FILE}`);
  if (!fs.existsSync(IMPORT_FILE)) {
    console.error(`FEHLER: Datei nicht gefunden: ${IMPORT_FILE}`);
    process.exit(1);
  }
  const docs = await readExportFile(IMPORT_FILE);
  console.log(`  ${docs.length} Dokument(e) eingelesen.`);

  if (docs.length === 0) {
    console.log('Nichts zu migrieren.');
    return;
  }

  // ── MySQL verbinden ──
  console.log(`MySQL verbinden: ${MYSQLHOST}:${MYSQLPORT} / ${MYSQLBASE}`);
  const conn = await mysql.createConnection({
    host: MYSQLHOST,
    port: MYSQLPORT,
    user: MYSQLUSER,
    password: MYSQLPASSWORD,
    database: MYSQLBASE,
  });

  await ensureTable(conn);
  console.log(`  Tabelle '${MYSQL_TABLE}' bereit.`);

  let inserted = 0;
  let updated  = 0;
  let errors   = 0;

  for (const doc of docs) {
    const row = normalizeDoc(doc);

    if (!row.curdate) {
      console.warn(`  SKIP: Dokument ohne curdate (_id=${doc._id})`);
      errors++;
      continue;
    }

    try {
      const [result] = await conn.query(
        `INSERT INTO \`${MYSQL_TABLE}\` (curdate, months, years, data, einheit)
         VALUES (?, ?, ?, ?, ?)
         ON DUPLICATE KEY UPDATE
           months = VALUES(months),
           years  = VALUES(years),
           data   = VALUES(data),
           einheit = VALUES(einheit),
           updated_at = CURRENT_TIMESTAMP`,
        [
          row.curdate,
          JSON.stringify(row.months),
          JSON.stringify(row.years),
          JSON.stringify(row.data),
          row.einheit,
        ]
      );
      // affectedRows=1 → INSERT, affectedRows=2 → UPDATE (ON DUPLICATE KEY)
      if (result.affectedRows === 1) {
        console.log(`  INSERT  curdate=${row.curdate}`);
        inserted++;
      } else {
        console.log(`  UPDATE  curdate=${row.curdate}`);
        updated++;
      }
    } catch (e) {
      console.error(`  FEHLER  curdate=${row.curdate}: ${e.message}`);
      errors++;
    }
  }

  await conn.end();

  console.log('\n── Ergebnis ──────────────────────────');
  console.log(`  Inserted : ${inserted}`);
  console.log(`  Updated  : ${updated}`);
  console.log(`  Errors   : ${errors}`);
  console.log(`  Gesamt   : ${docs.length}`);
}

migrate().catch((err) => {
  console.error('Fataler Fehler:', err);
  process.exit(1);
});