#!/usr/bin/env node

// ssb-viewer connects to sbot exactly once and hands the handle to index.js,
// which captures it in a closure behind http.createServer().listen(). There is
// no reconnect. So when sbot dies -- which on this box means "gets OOM-killed",
// after which run-server.sh restarts it -- the viewer keeps port 8807 open
// while holding a dead muxrpc connection, and never answers another request.
//
// That is the silent wedge. The fix is not to reconnect (index.js can't take a
// new handle) but to exit loudly, so the `while true` loop in run-ssb-viewer.sh
// restarts us with a fresh connection.

var PING_INTERVAL_MS = 60000
var PING_TIMEOUT_MS = 20000

function bail (why) {
  console.error('[viewer] ' + new Date().toISOString() + ' ' + why + ' — exiting so the run loop restarts us')
  process.exit(1)
}

require('ssb-client')(function (err, sbot, config) {
  // ssb-client already wraps this as "could not connect to sbot", so don't
  // prefix it again.
  if (err) return bail(String(err.message || err))

  // muxrpc emits 'closed' when the underlying stream ends
  // (see node_modules/muxrpc/index.js). This is the fast path.
  sbot.on('closed', function () {
    bail('sbot connection closed')
  })

  // Belt and braces: a half-open TCP connection can leave 'closed' unfired
  // while calls silently hang forever. Poll a cheap RPC to catch that case.
  if (typeof sbot.whoami === 'function') {
    var timer = setInterval(function () {
      var timeout = setTimeout(function () {
        bail('sbot did not answer whoami within ' + (PING_TIMEOUT_MS / 1000) + 's')
      }, PING_TIMEOUT_MS)
      sbot.whoami(function (err) {
        clearTimeout(timeout)
        if (err) bail('sbot whoami failed: ' + (err.message || err))
      })
    }, PING_INTERVAL_MS)
    // Don't hold the event loop open on our account.
    timer.unref()
  }

  require('.').init(sbot, config)
})