export type WindowOpenHandlerResult = { action: 'deny' } | { action: 'allow' }

export type NavigationGuardWebContents = {
  setWindowOpenHandler(handler: (details: { url: string }) => WindowOpenHandlerResult): void
  on(
    event: 'will-navigate',
    handler: (event: { preventDefault: () => void }, url: string) => void,
  ): unknown
}

export type NavigationGuardOptions = {
  openExternal: (url: string) => void
}

export function isHttpUrl(url: string): boolean {
  try {
    const { protocol } = new URL(url)
    return protocol === 'http:' || protocol === 'https:'
  } catch {
    return false
  }
}

/**
 * Main app window guard. The renderer is a single-page app loaded from a fixed
 * entry; it should never spawn an uncontrolled child window. Any window.open /
 * target=_blank with an http(s) URL is routed to the system browser and the
 * Electron popup is denied. We intentionally do NOT install a `will-navigate`
 * guard here so that dev HMR reloads and in-app navigations keep working.
 */
export function installMainWindowNavigationGuards(
  webContents: NavigationGuardWebContents,
  { openExternal }: NavigationGuardOptions,
): void {
  webContents.setWindowOpenHandler(({ url }) => {
    if (isHttpUrl(url)) openExternal(url)
    return { action: 'deny' }
  })
}

/**
 * Preview (WebContentsView) guard. The preview renders untrusted remote pages,
 * so it must keep working as a browser: in-page http(s) navigation is allowed.
 * Popups are denied (http(s) ones handed to the system browser), and navigation
 * to any non-http(s) scheme (file:, custom schemes) is blocked outright.
 */
export function installPreviewNavigationGuards(
  webContents: NavigationGuardWebContents,
  { openExternal }: NavigationGuardOptions,
): void {
  webContents.setWindowOpenHandler(({ url }) => {
    if (isHttpUrl(url)) openExternal(url)
    return { action: 'deny' }
  })
  webContents.on('will-navigate', (event, url) => {
    if (!isHttpUrl(url)) event.preventDefault()
  })
}