package main

import (
	"errors"
	"io"
	"strings"
	"sync/atomic"
	"testing"
	"time"

	stdio "git.novox.be/novox/mesh-sdk/go"
)

// TestRunStartsTheWatcherEvenWhenStdinIsAtEOF proves the watcher runs beside stdio.Serve in the one process the
// node's runtime launches (novox/hq ADR 0378 §9, as mesh-knowledge's serve starts go hear(k) and go
// background(k) before stdio.Serve), not only in a separate process something keeps asking over stdin. run is
// given stdin already at EOF, exactly what systemd gave the old separate `notify` process: it exited at once,
// every five seconds (novox/hq issue 859). The watcher must still be running once run has returned — proved by
// making it actually answer after run returns, not by the absence of a signal that nothing but the test's own
// cleanup could ever raise.
func TestRunStartsTheWatcherEvenWhenStdinIsAtEOF(t *testing.T) {
	started := make(chan struct{})
	ping := make(chan struct{})
	pong := make(chan struct{})

	fakeWatcher := func(n *Notifier) {
		close(started)
		for range ping {
			pong <- struct{}{}
		}
	}

	n := &Notifier{Store: newFakeStore()}
	n.init()

	done := make(chan error, 1)
	go func() { done <- run(n, fakeWatcher, strings.NewReader(""), io.Discard, nil) }()

	select {
	case <-started:
	case <-time.After(time.Second):
		t.Fatal("the watcher was not started before stdio.Serve returned")
	}

	select {
	case err := <-done:
		if err != nil {
			t.Fatalf("run over stdin at EOF: %v", err)
		}
	case <-time.After(time.Second):
		t.Fatal("run did not return once stdin reached EOF, as systemd gives a process nobody talks to")
	}

	// run has returned (stdio.Serve hit EOF at once); the watcher must still be live and answering, not merely
	// not yet torn down. A watcher that stopped when run returned would never take this ping.
	select {
	case ping <- struct{}{}:
	case <-time.After(time.Second):
		t.Fatal("the watcher is no longer running once run returned: it must not stop just because stdio.Serve did")
	}
	select {
	case <-pong:
	case <-time.After(time.Second):
		t.Fatal("the watcher did not answer once run returned")
	}
	close(ping)
}

// TestWatchRetriesASubscribeRefusalWithBackoffAndNeverExits proves watch no longer exits the process on a
// subscribe the runtime refuses — the old os.Exit(1) took mail-notifier.status and mail_notifier_health down
// with it — but retries with backoff and logs each refusal, as modules/mesh-knowledge's hear does (novox/hq
// issue 859, review round 1). A subscribe that fails twice then succeeds must leave the process serving (run
// still returns normally over stdin at EOF, never os.Exit) and the watcher subscribed (its third, successful
// call).
func TestWatchRetriesASubscribeRefusalWithBackoffAndNeverExits(t *testing.T) {
	var calls int32
	subscribed := make(chan struct{})
	fakeSubscribe := func(pattern string, handle func(stdio.Envelope) error) error {
		if atomic.AddInt32(&calls, 1) <= 2 {
			return errors.New("the runtime refused this subscribe")
		}
		close(subscribed)
		return nil
	}
	noSleep := func(time.Duration) {}

	n := &Notifier{Store: newFakeStore()}
	n.init()

	done := make(chan error, 1)
	go func() {
		done <- run(n, func(n *Notifier) { watchWith(n, fakeSubscribe, noSleep) },
			strings.NewReader(""), io.Discard, nil)
	}()

	select {
	case err := <-done:
		if err != nil {
			t.Fatalf("run over stdin at EOF: %v", err)
		}
	case <-time.After(time.Second):
		t.Fatal("run did not return once stdin reached EOF: a subscribe refusal must not hold up or kill the process")
	}

	select {
	case <-subscribed:
	case <-time.After(time.Second):
		t.Fatal("the watcher never subscribed after its first two refusals")
	}

	if got := atomic.LoadInt32(&calls); got != 3 {
		t.Fatalf("subscribe was called %d time(s), want 3 (two refusals, then the one that succeeded)", got)
	}
}