package web

import (
	"io"
	"log"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"strings"
	"sync/atomic"
	"testing"
	"time"

	"gitea.dooplex.hu/admin/felhom-controller/internal/backup"
	"gitea.dooplex.hu/admin/felhom-controller/internal/config"
	"gitea.dooplex.hu/admin/felhom-controller/internal/settings"
)

// blockProvider is a StackDataProvider whose StopStack blocks on a channel — so a Tier-2 restore
// parks mid-flight while the test asserts the HANDLER already returned (async) and that a concurrent
// POST is refused without launching a second restore.
type blockProvider struct {
	hdd     string
	release chan struct{}
	stops   int32 // atomic: number of StopStack calls == number of restores that actually launched
}

func (p *blockProvider) GetStackComposePath(string) (string, bool) { return "", false }
func (p *blockProvider) ListDeployedStacks() []backup.StackSummary { return nil }
func (p *blockProvider) GetStackHDDMounts(string) []string         { return nil }
func (p *blockProvider) GetStackHDDPath(string) string             { return p.hdd }
func (p *blockProvider) GetDockerVolumes(string) []string          { return nil }
func (p *blockProvider) StopStack(string) error {
	atomic.AddInt32(&p.stops, 1)
	<-p.release // park here until the test releases it
	return nil
}
func (p *blockProvider) StartStack(string) error         { return nil }
func (p *blockProvider) RefreshAndIsRunning(string) bool { return true }
func (p *blockProvider) GetStackRecoveryInfo(string) (backup.RecoveryInfo, bool) {
	return backup.RecoveryInfo{}, false
}
func (p *blockProvider) GetStackClassifiedBinds(string) ([]backup.ClassifiedBind, bool) {
	return nil, false
}
func (p *blockProvider) RecoverStackSecrets(string, []string) map[string]string { return nil }
func (p *blockProvider) RecreateStackFromUnit(string, string, map[string]string) error {
	return nil
}

func newAsyncRestoreServer(t *testing.T) (*Server, *blockProvider, *backup.Manager) {
	t.Helper()
	tmp := t.TempDir()
	live := filepath.Join(tmp, "usb")
	dest := filepath.Join(tmp, "flash")
	lg := log.New(io.Discard, "", 0)
	sett, err := settings.Load(filepath.Join(tmp, "settings.json"), lg)
	if err != nil {
		t.Fatal(err)
	}
	for _, p := range []string{live, dest} {
		if err := sett.AddStoragePath(settings.StoragePath{Path: p, Label: filepath.Base(p)}); err != nil {
			t.Fatal(err)
		}
	}
	if err := sett.SetCrossDriveConfig("app", &settings.CrossDriveBackup{
		Enabled: true, Method: "rsync", DestinationPath: dest, LastRun: "2026-07-06T03:30:00Z", LastStatus: "ok",
	}); err != nil {
		t.Fatal(err)
	}
	// a recorded v2 Tier-2 copy (marker + an hdd/ leg) so RestoreTier2Files proceeds to StopStack.
	destBase := filepath.Join(dest, "backups", "secondary", "app")
	if err := os.MkdirAll(filepath.Join(destBase, "hdd", "appdata"), 0o755); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(destBase, ".felhom-tier2-layout"), []byte("2"), 0o644); err != nil {
		t.Fatal(err)
	}
	cfg := &config.Config{}
	cfg.Paths.DataDir = tmp
	m := backup.NewManager(cfg, sett, lg)
	prov := &blockProvider{hdd: live, release: make(chan struct{})}
	m.SetStackProvider(prov)
	s := &Server{cfg: cfg, backupMgr: m, logger: lg}
	return s, prov, m
}

func postTier2(s *Server) *httptest.ResponseRecorder {
	req := httptest.NewRequest(http.MethodPost, "/backup/tier2/restore", strings.NewReader("stack_name=app"))
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	w := httptest.NewRecorder()
	s.backupTier2RestoreHandler(w, req)
	return w
}

func waitFor(t *testing.T, cond func() bool, msg string) {
	t.Helper()
	// Budget past waitForHealthy's 3s post-restore settling sleep (+ copier).
	for i := 0; i < 700; i++ {
		if cond() {
			return
		}
		time.Sleep(10 * time.Millisecond)
	}
	t.Fatalf("timeout waiting for: %s", msg)
}

// B1 — the restore handler returns INSTANTLY (302) while the restore runs in the background, and the
// op-status transitions running → terminal. RED-PROOF: on the pre-fix synchronous handler (calling
// RestoreTier2Files inline) this POST blocks in StopStack until the channel is released, so the
// sub-500ms response assertion FAILS.
func TestBackupTier2Restore_AsyncReturnsInstantly(t *testing.T) {
	s, prov, m := newAsyncRestoreServer(t)

	start := time.Now()
	w := postTier2(s)
	elapsed := time.Since(start)

	if elapsed > 500*time.Millisecond {
		t.Fatalf("handler blocked %v — restore is not async (the F4 shape)", elapsed)
	}
	if w.Code != http.StatusFound {
		t.Fatalf("want 302, got %d", w.Code)
	}
	if loc := w.Header().Get("Location"); !strings.Contains(loc, "elindult") {
		t.Fatalf("redirect should carry the 'elindult' flash; got %q", loc)
	}
	// the background restore is now parked in StopStack → op-status shows running.
	waitFor(t, func() bool { return m.RestoreStatus().Running }, "restore op running")
	st := m.RestoreStatus()
	if st.Op != "tier2-restore" || st.Stack != "app" {
		t.Fatalf("running status = %+v", st)
	}
	// release → the restore completes → terminal status.
	close(prov.release)
	waitFor(t, func() bool { return !m.RestoreStatus().Running && m.RestoreStatus().Last != nil }, "restore terminal")
	if got := atomic.LoadInt32(&prov.stops); got != 1 {
		t.Fatalf("StopStack called %d times, want exactly 1", got)
	}
}

// B2 — a concurrent restore POST while one runs is REFUSED (fast-path IsRunning) and does NOT launch a
// second restore. RED-PROOF: removing the IsRunning() fast-path lets the second POST launch a second
// goroutine → StopStack count becomes 2.
func TestBackupTier2Restore_DoubleClickRefused(t *testing.T) {
	s, prov, m := newAsyncRestoreServer(t)

	// first restore → parks in StopStack (acquires the single-flight running flag).
	_ = postTier2(s)
	waitFor(t, func() bool { return m.IsRunning() }, "first restore holding the single-flight lock")

	// second restore while the first runs → refused with the "már fut" flash, no second launch.
	w2 := postTier2(s)
	if loc := w2.Header().Get("Location"); !strings.Contains(loc, "m%C3%A1r+fut") && !strings.Contains(loc, "már fut") {
		t.Fatalf("second POST should be refused with 'már fut'; got %q", loc)
	}
	// IsRunning flips before the goroutine reaches StopStack — wait for the FIRST stop to land, so
	// the ==1 assertion below measures "no second launch", not goroutine scheduling (parallel-load flake).
	waitFor(t, func() bool { return atomic.LoadInt32(&prov.stops) >= 1 }, "first restore reached StopStack")
	if got := atomic.LoadInt32(&prov.stops); got != 1 {
		t.Fatalf("double-click launched a second restore: StopStack count = %d, want 1", got)
	}

	close(prov.release)
	waitFor(t, func() bool { return !m.IsRunning() }, "first restore done")
}