package storage

import (
	"os"
	"path/filepath"
	"runtime"
	"strings"
	"testing"
)

// The data-bearing partition path binds the disk id + the part number + the fs-UUID (felhom.eu architecture/16 §6,
// agent v0.158.0). The wipe re-resolve (localapi antiRetargetResolveExpect) formats only when resolve(id) succeeds AND
// DeviceDurableID(that device) == id — the round trip these tests pin, in the three ways a target can move.

type partFixture struct{ base, root string }

func newPartFixture(t *testing.T) partFixture {
	t.Helper()
	if runtime.GOOS == "windows" {
		t.Skip("symlink fixtures run on Linux")
	}
	f := partFixture{base: t.TempDir()}
	f.root = filepath.Join(f.base, "disk")
	for _, d := range []string{"sdb", "sdb1", "sdb2", "sdc2"} {
		if err := os.WriteFile(filepath.Join(f.base, d), []byte("x"), 0o600); err != nil {
			t.Fatal(err)
		}
	}
	os.MkdirAll(filepath.Join(f.root, "by-id"), 0o755)
	os.MkdirAll(filepath.Join(f.root, "by-uuid"), 0o755)
	withDevDiskRoot(t, f.root)
	return f
}

func (f partFixture) link(t *testing.T, sub, name, dev string) {
	t.Helper()
	p := filepath.Join(f.root, sub, name)
	os.Remove(p)
	if err := os.Symlink(filepath.Join(f.base, dev), p); err != nil {
		t.Fatal(err)
	}
}

func (f partFixture) dev(name string) string { return filepath.Join(f.base, name) }

func (f partFixture) standard(t *testing.T) {
	f.link(t, "by-id", "wwn-0x5000aaaa", "sdb")
	f.link(t, "by-id", "ata-TOSHIBA_MQ04_65NOP-part1", "sdb1")
	f.link(t, "by-id", "wwn-0x5000aaaa-part1", "sdb1")
	f.link(t, "by-id", "wwn-0x5000aaaa-part2", "sdb2")
	f.link(t, "by-uuid", "1111-films", "sdb2")
}

func roundTrip(id string) (string, bool) {
	dev, err := ResolveDurableDevice(id)
	if err != nil {
		return "", false
	}
	again, err := DeviceDurableID(dev)
	return dev, err == nil && again == id
}

func TestPartitionWipeID_BindsDiskPartAndFilesystem(t *testing.T) {
	f := newPartFixture(t)
	f.standard(t)
	id, err := DeviceDurableID(f.dev("sdb2"))
	if err != nil || id != "byid:wwn-0x5000aaaa-part2+fsuuid:1111-films" {
		t.Fatalf("a part with a filesystem: want disk id + part + fs-UUID, got %q %v", id, err)
	}
	if dev, ok := roundTrip(id); !ok || dev != f.dev("sdb2") {
		t.Fatalf("the unchanged part must round-trip, got %q %v", dev, ok)
	}
	// A blank part (no filesystem) and a whole disk keep the plain by-id binding.
	if id1, _ := DeviceDurableID(f.dev("sdb1")); id1 != "byid:wwn-0x5000aaaa-part1" {
		t.Fatalf("a blank part: want the plain part link, got %q", id1)
	}
	if idDisk, _ := DeviceDurableID(f.dev("sdb")); idDisk != "byid:wwn-0x5000aaaa" {
		t.Fatalf("a whole disk keeps today's id, got %q", idDisk)
	}
}

func TestPartitionWipeID_ReformattedPartRefuses(t *testing.T) {
	f := newPartFixture(t)
	f.standard(t)
	id, _ := DeviceDurableID(f.dev("sdb2"))
	os.Remove(filepath.Join(f.root, "by-uuid", "1111-films"))
	f.link(t, "by-uuid", "2222-other", "sdb2") // someone reformatted the part since the household confirmed
	if _, ok := roundTrip(id); ok {
		t.Fatalf("a reformatted part must not round-trip (the wipe would hit a different filesystem)")
	}
}

func TestPartitionWipeID_LinkMovedToAnotherDiskRefuses(t *testing.T) {
	f := newPartFixture(t)
	f.standard(t)
	id, _ := DeviceDurableID(f.dev("sdb2"))
	f.link(t, "by-id", "wwn-0x5000aaaa-part2", "sdc2") // a different node took the part link; the fs is still sdb2
	if _, err := ResolveDurableDevice(id); err == nil || !strings.Contains(err.Error(), "different devices") {
		t.Fatalf("the part link and its filesystem on different devices must refuse, got %v", err)
	}
}

func TestPartitionWipeID_RefusesAForgedCompound(t *testing.T) {
	f := newPartFixture(t)
	f.standard(t)
	f.link(t, "by-uuid", "3333-whole", "sdb") // a filesystem straight on the whole disk: both halves name sdb
	for _, id := range []string{"byid:wwn-0x5000aaaa+fsuuid:3333-whole", "byid:wwn-0x5000aaaa-part2+fsuuid:../x"} {
		if _, err := ResolveDurableDevice(id); err == nil {
			t.Fatalf("%q must be refused", id)
		}
	}
}