package backup

import (
	"context"
	"os"
	"strings"
	"sync"
	"testing"

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

// R-411 / R-408 — the single-writer flag on the customer restore paths.
//
// These drive the real functions through the restic exec seam (`SetOffboxRunner`), which REUSE.md
// names as the way to see the argv — replacing `resticStep` would hide the `unlock --remove-all`
// escalation from exactly the assertion that must see it.

// lockHarness records every restic argv and lets a test hold the flag.
type lockHarness struct {
	m    *Manager
	mu   sync.Mutex
	argv [][]string
}

func newLockHarness(t *testing.T, stacks ...string) *lockHarness {
	t.Helper()
	m, sett := newOffboxManager(t)
	drive := t.TempDir()
	if err := sett.AddStoragePath(settings.StoragePath{Path: drive, Label: "data", Schedulable: true}); err != nil {
		t.Fatal(err)
	}
	deployed := map[string]bool{}
	for _, s := range stacks {
		deployed[s] = true
	}
	m.SetStackProvider(&offbox3aProvider{
		hdd: map[string]string{}, binds: map[string][]ClassifiedBind{},
		has: map[string]bool{}, deployed: deployed,
	})
	h := &lockHarness{m: m}
	m.SetOffboxLatestSnapshotFn(func(_ context.Context, stack string) (string, []string, error) {
		return "snap-" + stack, []string{"/mnt/sys_drive/felhom-data/backups/primary/" + stack}, nil
	})
	m.SetOffboxRunner(func(_ context.Context, _ []string, args ...string) ([]byte, error) {
		h.mu.Lock()
		h.argv = append(h.argv, append([]string{}, args...))
		h.mu.Unlock()
		return []byte("{}"), nil
	})
	m.SetOffboxFreeFn(func(string) int64 { return 100 << 30 })
	return h
}

func (h *lockHarness) allArgs() [][]string {
	h.mu.Lock()
	defer h.mu.Unlock()
	return h.argv
}

// TestR411_ScratchRestoreTakesTheSingleWriterFlag — A1.
func TestR411_ScratchRestoreTakesTheSingleWriterFlag(t *testing.T) {
	h := newLockHarness(t, "kimai")
	// Hold the flag as a sibling operation would.
	if err := h.m.AcquireRunningForTest(); err != nil {
		t.Fatalf("could not take the flag: %v", err)
	}
	err := h.m.RestoreOffboxScratch(context.Background(), "kimai", false)
	if err == nil {
		t.Fatal("a scratch restore must REFUSE while the single-writer flag is held — before this fix it ran anyway, which is R-411")
	}
	if len(h.allArgs()) != 0 {
		t.Fatalf("a refused restore must invoke restic ZERO times; got %v", h.allArgs())
	}
}

// TestR411_PrepareFullAlsoTakesTheFlag — the SECOND entry point, found while fixing the first.
// The customer's real UI flow reaches this one first, and it is the one that shells `restic stats`.
func TestR411_PrepareFullAlsoTakesTheFlag(t *testing.T) {
	h := newLockHarness(t, "kimai")
	if err := h.m.AcquireRunningForTest(); err != nil {
		t.Fatal(err)
	}
	if _, err := h.m.OffboxRestorePrepareFull(context.Background(), "kimai"); err == nil {
		t.Fatal("the full-restore PREPARE must refuse while the flag is held — it shells `restic stats`, which takes a repository lock")
	}
	if len(h.allArgs()) != 0 {
		t.Fatalf("a refused prepare must invoke restic ZERO times; got %v", h.allArgs())
	}
}

// TestR411_SharesScratchRestoreAlsoTakesTheFlag — the third, found by the R-408 walk.
func TestR411_SharesScratchRestoreAlsoTakesTheFlag(t *testing.T) {
	h := newLockHarness(t)
	if err := h.m.AcquireRunningForTest(); err != nil {
		t.Fatal(err)
	}
	if err := h.m.RestoreSharesScratch(context.Background()); err == nil {
		t.Fatal("the shares scratch restore must refuse while the flag is held — it runs unlockStale + resticStep, R-411's exact shape")
	}
	if len(h.allArgs()) != 0 {
		t.Fatalf("a refused shares restore must invoke restic ZERO times; got %v", h.allArgs())
	}
}

// TestR411_NoUnlockRemoveAllInAnyArgv — A3, the non-effect that matters.
//
// RED-PROOF (run 2026-09-01): removing the acquire from `RestoreOffboxScratch` lets the restore run
// while the flag is held, so an integrity check could collide with it — the state this asserts is
// impossible. The direct form of the red-proof is `TestR408_…`, which names the function.
func TestR411_NoUnlockRemoveAllInAnyArgv(t *testing.T) {
	h := newLockHarness(t, "kimai")
	if err := h.m.RestoreOffboxScratch(context.Background(), "kimai", false); err != nil {
		t.Fatalf("an idle-box restore must succeed: %v", err)
	}
	for _, args := range h.allArgs() {
		joined := strings.Join(args, " ")
		if strings.Contains(joined, "--remove-all") {
			t.Fatalf("the escalation fired during an ordinary restore: %s", joined)
		}
	}
	if len(h.allArgs()) == 0 {
		t.Fatal("no restic invocation at all — the assertion above ran over nothing")
	}
}

// TestR411_RestoreStillWorksWhenIdle — Scenario C. The flag must not make the common case refuse.
func TestR411_RestoreStillWorksWhenIdle(t *testing.T) {
	h := newLockHarness(t, "kimai")
	if err := h.m.RestoreOffboxScratch(context.Background(), "kimai", false); err != nil {
		t.Fatalf("a restore on an idle box must still work: %v", err)
	}
	var sawRestore bool
	for _, args := range h.allArgs() {
		if containsArg(args, "restore") {
			sawRestore = true
		}
	}
	if !sawRestore {
		t.Fatal("no restore was issued")
	}
}

// TestR411_FlagIsReleasedOnEveryPath — A5. A flag that leaks would wedge every nightly job.
func TestR411_FlagIsReleasedOnEveryPath(t *testing.T) {
	t.Run("success", func(t *testing.T) {
		h := newLockHarness(t, "kimai")
		if err := h.m.RestoreOffboxScratch(context.Background(), "kimai", false); err != nil {
			t.Fatal(err)
		}
		if err := h.m.AcquireRunningForTest(); err != nil {
			t.Fatal("the flag was NOT released after a successful restore")
		}
	})
	t.Run("restic error", func(t *testing.T) {
		h := newLockHarness(t, "kimai")
		h.m.SetOffboxRunner(func(_ context.Context, _ []string, _ ...string) ([]byte, error) {
			return []byte("boom"), os.ErrPermission
		})
		_ = h.m.RestoreOffboxScratch(context.Background(), "kimai", false)
		if err := h.m.AcquireRunningForTest(); err != nil {
			t.Fatal("the flag was NOT released after a failed restore")
		}
	})
	t.Run("early refusal", func(t *testing.T) {
		h := newLockHarness(t, "kimai")
		_ = h.m.RestoreOffboxScratch(context.Background(), "no such stack!!", false)
		if err := h.m.AcquireRunningForTest(); err != nil {
			t.Fatal("the flag was NOT released after an early refusal")
		}
	})
	t.Run("prepare", func(t *testing.T) {
		h := newLockHarness(t, "kimai")
		_, _ = h.m.OffboxRestorePrepareFull(context.Background(), "kimai")
		if err := h.m.AcquireRunningForTest(); err != nil {
			t.Fatal("the flag was NOT released after the prepare step")
		}
	})
}