//go:build linux

package host

import (
	"errors"
	"os"
	"path/filepath"
	"strconv"
	"testing"
)

func rev3HoldTarget(t *testing.T, fx *writersKernelFixture, pid, fd int, target string) {
	t.Helper()
	dir := filepath.Join(fx.proc, strconv.Itoa(pid), "task", strconv.Itoa(pid), "fd")
	if err := os.MkdirAll(dir, 0o700); err != nil {
		t.Fatal(err)
	}
	if err := os.Symlink(target, filepath.Join(dir, strconv.Itoa(fd))); err != nil {
		t.Fatal(err)
	}
}

func TestRev3NoProcessCoversDeletedDatabaseAndWAL(t *testing.T) {
	for _, suffix := range []string{"", "-wal"} {
		t.Run(suffix, func(t *testing.T) {
			fx := newWritersKernelFixture(t)
			fx.dropAgentHolds(t)
			target := fx.db + suffix
			for _, path := range []string{fx.db, fx.db + "-wal"} {
				if err := os.Remove(path); err != nil {
					t.Fatal(err)
				}
			}
			rev3HoldTarget(t, fx, 31, 8, target+" (deleted)")
			if _, err := fx.noProcess(t, false); err == nil {
				t.Fatalf("deleted holder passed: %v", err)
			}
		})
	}
}

func TestRev3NoProcessCoversNestedInstallationFiles(t *testing.T) {
	fx := newWritersKernelFixture(t)
	fx.dropAgentHolds(t)
	nested := filepath.Join(filepath.Dir(fx.db), "sqlite", "scratch.db")
	if err := os.MkdirAll(filepath.Dir(nested), 0o700); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(nested, nil, 0o600); err != nil {
		t.Fatal(err)
	}
	rev3HoldTarget(t, fx, 32, 9, nested)
	if _, err := fx.noProcess(t, false); !errors.Is(err, ErrClaimStopIdentity) {
		t.Fatalf("nested holder passed: %v", err)
	}
}

func TestRev3NoProcessScansWhenInstallationDirectoryIsEmpty(t *testing.T) {
	fx := newWritersKernelFixture(t)
	fx.dropAgentHolds(t)
	if err := os.Remove(fx.db); err != nil {
		t.Fatal(err)
	}
	if err := os.Remove(fx.db + "-wal"); err != nil {
		t.Fatal(err)
	}
	target := filepath.Join(filepath.Dir(fx.db), "gone.db")
	rev3HoldTarget(t, fx, 33, 10, target+" (deleted)")
	if _, err := fx.noProcess(t, false); !errors.Is(err, ErrClaimStopIdentity) {
		t.Fatalf("empty directory suppressed descriptor scan: %v", err)
	}
}

func TestRev3NoProcessPrefixHasPathBoundary(t *testing.T) {
	fx := newWritersKernelFixture(t)
	fx.dropAgentHolds(t)
	sibling := filepath.Dir(fx.db) + "-old"
	if err := os.Mkdir(sibling, 0o700); err != nil {
		t.Fatal(err)
	}
	target := filepath.Join(sibling, "data.db")
	if err := os.WriteFile(target, nil, 0o600); err != nil {
		t.Fatal(err)
	}
	rev3HoldTarget(t, fx, 34, 11, target)
	if _, err := fx.noProcess(t, false); err != nil {
		t.Fatalf("prefix sibling matched: %v", err)
	}
}

func TestRev3NoProcessDescriptorScanErrorsFailClosed(t *testing.T) {
	fx := newWritersKernelFixture(t)
	fx.dropAgentHolds(t)
	dir := filepath.Join(fx.proc, "35", "task", "35", "fd")
	if err := os.MkdirAll(dir, 0o700); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(dir, "12"), nil, 0o600); err != nil {
		t.Fatal(err)
	}
	if _, err := fx.noProcess(t, false); err == nil {
		t.Fatal("unreadable descriptor entry passed")
	}
}

func TestRev3NoProcessCoversUnlinkedNestedFile(t *testing.T) {
	fx := newWritersKernelFixture(t)
	fx.dropAgentHolds(t)
	for _, p := range []string{fx.db, fx.db + "-wal"} {
		if err := os.Remove(p); err != nil {
			t.Fatal(err)
		}
	}
	nested := filepath.Join(filepath.Dir(fx.db), "sqlite", "gone.db")
	if err := os.MkdirAll(filepath.Dir(nested), 0700); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(nested, nil, 0600); err != nil {
		t.Fatal(err)
	}
	if err := os.Remove(nested); err != nil {
		t.Fatal(err)
	}
	rev3HoldTarget(t, fx, 36, 13, nested+" (deleted)")
	if _, err := fx.noProcess(t, false); !errors.Is(err, ErrClaimStopIdentity) {
		t.Fatalf("unlinked nested holder passed: %v", err)
	}
}