package stacks

import (
	"io"
	"log"
	"os"
	"path/filepath"
	"sync"
	"testing"
	"time"
)

// R-1351: at a guest boot EnsureBaseStack's `compose up` and web.SyncFileBrowserMounts' `compose up --force-recreate` ran
// in the same second; one lost with „Conflict. The container name … is already in use" and a false first-boot WARN. The
// two paths now share one lock: the base stack's bring-up holds it around its FileBrowser step, the web sync around its
// compose call (TestFileBrowserSyncRunsInsideTheStackLock pins that side, internal/web).
//
// RED-PROOF (2026-11-02): seen failing before the lock existed (build: WithFileBrowserStack); with ensureFileBrowser not
// taking the lock it fails on „overlap".
func TestR1351_TheTwoFileBrowserStartPathsNeverOverlap(t *testing.T) {
	dir := t.TempDir()
	if err := os.WriteFile(filepath.Join(dir, "docker-compose.yml"), []byte("services: {}\n"), 0o644); err != nil {
		t.Fatal(err)
	}
	m := &Manager{logger: log.New(io.Discard, "", 0)}
	var mu sync.Mutex
	inside, overlaps := 0, 0
	enter := func() {
		mu.Lock()
		inside++
		if inside > 1 {
			overlaps++
		}
		mu.Unlock()
		time.Sleep(30 * time.Millisecond)
		mu.Lock()
		inside--
		mu.Unlock()
	}
	m.fbComposeUpFn = func(string) error { enter(); return nil }
	m.fbRunningFn = func() bool { return false }

	var wg sync.WaitGroup
	for i := 0; i < 4; i++ {
		wg.Add(2)
		go func() {
			defer wg.Done()
			if err := m.ensureFileBrowser(dir); err != nil {
				t.Error(err)
			}
		}()
		go func() { defer wg.Done(); m.WithFileBrowserStack(enter) }()
	}
	wg.Wait()
	if overlaps != 0 {
		t.Fatalf("overlap: the two start paths ran compose at the same time %d time(s) — the „Conflict” of R-1351", overlaps)
	}
}