/**
 * LandveX Finance — Strukturerad JSON-loggning
 * Sprint 3: Observability
 */

const isDev = process.env.NODE_ENV === 'development';
const LOG_LEVEL = process.env.LOG_LEVEL || 'info';

const LEVELS = { debug: 0, info: 1, warn: 2, error: 3 };

function shouldLog(level) {
  return LEVELS[level] >= LEVELS[LOG_LEVEL];
}

/**
 * Huvudloggningsfunktion
 * @param {string} level - debug|info|warn|error
 * @param {string} event - Event-namn (snake_case)
 * @param {object} meta - Metadata
 */
export function logFinance(level, event, meta = {}) {
  if (!shouldLog(level)) return;

  const entry = {
    ts: new Date().toISOString(),
    svc: 'finance',
    lvl: level.toUpperCase(),
    evt: event,
    tid: meta.tenant || meta.tid || 'unknown',
    uid: meta.user || meta.uid || 'anonymous',
    dur_ms: meta.duration || meta.dur_ms,
    trace_id: meta.traceId || meta.trace_id,
    ...meta.context,
  };

  // Fel-objekt
  if (meta.error || meta.err) {
    const err = meta.error || meta.err;
    entry.err = {
      msg: err.message,
      code: err.code || 'UNKNOWN',
      stack: isDev ? err.stack : undefined,
    };
  }

  // Rensa undefined-värden
  Object.keys(entry).forEach(k => {
    if (entry[k] === undefined) delete entry[k];
  });

  // Output
  const line = JSON.stringify(entry);
  if (level === 'error') {
    console.error(line);
  } else if (level === 'warn') {
    console.warn(line);
  } else {
    console.log(line);
  }
}

// Convenience wrappers
export const financeDebug = (evt, meta) => logFinance('debug', evt, meta);
export const financeInfo  = (evt, meta) => logFinance('info',  evt, meta);
export const financeWarn  = (evt, meta) => logFinance('warn',  evt, meta);
export const financeError = (evt, meta) => logFinance('error', evt, meta);

// Request-logger middleware
export function requestLogger(req, res, next) {
  const start = Date.now();
  const tid = req.headers['x-tenant-id'] || 'unknown';
  const uid = req.user?.email || req.headers['x-user-id'] || 'anonymous';

  res.on('finish', () => {
    const duration = Date.now() - start;
    const level = res.statusCode >= 500 ? 'error' : res.statusCode >= 400 ? 'warn' : 'info';

    logFinance(level, 'http_request', {
      tenant: tid,
      user: uid,
      duration,
      context: {
        method: req.method,
        path: req.path,
        route: req.route?.path,
        status: res.statusCode,
        content_length: res.get('content-length'),
        user_agent: req.get('user-agent'),
        ip: req.ip,
      },
    });
  });

  next();
}