import App from './App.svelte'

// ===== Global frontend error diagnostics =====
// These catch runtime errors that would otherwise cause a silent blank window.

window.addEventListener('error', (event) => {
  const msg = event.error ? String(event.error) : event.message
  const stack = event.error && event.error.stack ? event.error.stack : ''
  console.error('[Frontend Error]', msg, stack)
  try {
    if (window['go'] && window['go']['main'] && window['go']['main']['App'] && typeof window['go']['main']['App']['FrontendLog'] === 'function') {
      window['go']['main']['App']['FrontendLog']('error', msg, stack)
    }
  } catch (e) {
    // Backend not ready — ignore
  }
})

window.addEventListener('unhandledrejection', (event) => {
  const reason = event.reason
  const msg = reason instanceof Error ? String(reason) : JSON.stringify(reason)
  const stack = reason instanceof Error && reason.stack ? reason.stack : ''
  console.error('[Unhandled Promise Rejection]', msg, stack)
  try {
    if (window['go'] && window['go']['main'] && window['go']['main']['App'] && typeof window['go']['main']['App']['FrontendLog'] === 'function') {
      window['go']['main']['App']['FrontendLog']('error', 'Unhandled rejection: ' + msg, stack)
    }
  } catch (e) {
    // Backend not ready — ignore
  }
})

// Mount App with error fallback
try {
  new App({
    target: document.getElementById('app')
  })
} catch (e) {
  console.error('[Fatal] App mount failed:', e)
  const el = document.getElementById('app')
  if (el) {
    el.innerHTML = '<div style="padding:24px;color:#ff6b6b;font-family:monospace;white-space:pre-wrap">'
      + '<h2>Frontend Runtime Error</h2>'
      + '<p>' + String(e) + '</p>'
      + (e.stack ? '<pre>' + e.stack + '</pre>' : '')
      + '</div>'
  }
}