package storage

import (
	"testing"
	"time"

	"github.com/seaweedfs/seaweedfs/weed/storage/needle"
	"github.com/seaweedfs/seaweedfs/weed/storage/super_block"
	"github.com/seaweedfs/seaweedfs/weed/storage/types"
	"github.com/seaweedfs/seaweedfs/weed/util"
)

// TestVolumeTtlClockSurvivesDeletes reproduces the delete-traffic TTL bug:
// deletes append a tombstone to the .dat, which moves the file's mtime, and
// the loader read the TTL clock back from that mtime. A volume taking delete
// traffic therefore had expired() re-armed for another full TTL on every
// restart and was never reclaimed. The clock has to come from the newest
// write instead.
func TestVolumeTtlClockSurvivesDeletes(t *testing.T) {
	dir := t.TempDir()
	ttl, err := needle.ReadTTL("5m")
	if err != nil {
		t.Fatalf("read ttl: %v", err)
	}

	v, err := NewVolume(dir, dir, "", 1, NeedleMapInMemory, &super_block.ReplicaPlacement{}, ttl, 0, needle.GetCurrentVersion(), 0, 0)
	if err != nil {
		t.Fatalf("volume creation: %v", err)
	}

	// Backdate the writes on disk so the last one sits well outside the TTL,
	// while the tombstones below leave the .dat mtime at now.
	lastWriteNs := uint64(time.Now().Add(-2 * time.Hour).UnixNano())
	for i := 1; i <= 3; i++ {
		n := newRandomNeedle(uint64(i))
		offset, _, _, err := v.writeNeedle2(n, true, false, false)
		if err != nil {
			t.Fatalf("write needle %d: %v", i, err)
		}
		backdateAppendAtNs(t, v, int64(offset), n.Size, lastWriteNs)
	}
	// More than one tombstone: the scan has to walk back over the whole run of
	// them to reach a write.
	for _, id := range []uint64{2, 3} {
		if _, err := v.doDeleteRequest(newEmptyNeedle(id)); err != nil {
			t.Fatalf("delete needle %d: %v", id, err)
		}
	}
	contentSize := v.ContentSize()
	v.Close()

	reloaded, err := NewVolume(dir, dir, "", 1, NeedleMapInMemory, &super_block.ReplicaPlacement{}, ttl, 0, needle.GetCurrentVersion(), 0, 0)
	if err != nil {
		t.Fatalf("reload: %v", err)
	}
	defer reloaded.Close()

	if got, want := reloaded.lastModifiedTsSeconds, lastWriteNs/uint64(time.Second); got != want {
		t.Errorf("TTL clock recovered as %d, want the last write at %d", got, want)
	}
	if !reloaded.expired(contentSize, 1024*1024) {
		t.Error("a TTL volume whose last write is 2h old must be expired after a reload")
	}
}

// TestVolumeTtlClockKeepsMtimeWithoutRecoverableWrite covers a TTL volume whose
// needles carry no append timestamp: the loader must stay on the .dat mtime
// rather than treat the volume as written at the epoch and drop it on sight.
func TestVolumeTtlClockKeepsMtimeWithoutRecoverableWrite(t *testing.T) {
	dir := t.TempDir()
	ttl, err := needle.ReadTTL("5m")
	if err != nil {
		t.Fatalf("read ttl: %v", err)
	}

	v, err := NewVolume(dir, dir, "", 1, NeedleMapInMemory, &super_block.ReplicaPlacement{}, ttl, 0, needle.Version2, 0, 0)
	if err != nil {
		t.Fatalf("volume creation: %v", err)
	}
	if _, _, _, err := v.writeNeedle2(newRandomNeedle(1), true, false, false); err != nil {
		t.Fatalf("write needle: %v", err)
	}
	contentSize := v.ContentSize()
	v.Close()

	reloaded, err := NewVolume(dir, dir, "", 1, NeedleMapInMemory, &super_block.ReplicaPlacement{}, ttl, 0, needle.Version2, 0, 0)
	if err != nil {
		t.Fatalf("reload: %v", err)
	}
	defer reloaded.Close()

	if reloaded.expired(contentSize, 1024*1024) {
		t.Error("a just-written volume must not be expired after a reload")
	}
}

// TestVolumeTtlClockAfterVacuumTakesNewestWrite covers the one layout where a
// .dat's order does not track its write order: vacuum rewrites it by key, and
// an overwrite keeps its original, lower key. Reading the position rather than
// the timestamps would recover the highest-key needle's older write time and
// expire the volume before the overwrite has lived out its TTL.
func TestVolumeTtlClockAfterVacuumTakesNewestWrite(t *testing.T) {
	dir := t.TempDir()
	ttl, err := needle.ReadTTL("5m")
	if err != nil {
		t.Fatalf("read ttl: %v", err)
	}

	v, err := NewVolume(dir, dir, "", 1, NeedleMapInMemory, &super_block.ReplicaPlacement{}, ttl, 0, needle.GetCurrentVersion(), 0, 0)
	if err != nil {
		t.Fatalf("volume creation: %v", err)
	}

	// Needle 1 is overwritten last but sorts first, so vacuum leaves it at the
	// head of the .dat with the newest timestamp of the three.
	oldWriteNs := uint64(time.Now().Add(-2 * time.Hour).UnixNano())
	newWriteNs := uint64(time.Now().Add(-time.Minute).UnixNano())
	for _, w := range []struct {
		id uint64
		ns uint64
	}{{2, oldWriteNs}, {3, oldWriteNs}, {1, newWriteNs}} {
		n := newRandomNeedle(w.id)
		offset, _, _, err := v.writeNeedle2(n, true, false, false)
		if err != nil {
			t.Fatalf("write needle %d: %v", w.id, err)
		}
		backdateAppendAtNs(t, v, int64(offset), n.Size, w.ns)
	}
	if err := v.CompactByIndex(nil); err != nil {
		t.Fatalf("compact: %v", err)
	}
	if err := v.CommitCompact(); err != nil {
		t.Fatalf("commit compact: %v", err)
	}
	contentSize := v.ContentSize()
	v.Close()

	reloaded, err := NewVolume(dir, dir, "", 1, NeedleMapInMemory, &super_block.ReplicaPlacement{}, ttl, 0, needle.GetCurrentVersion(), 0, 0)
	if err != nil {
		t.Fatalf("reload: %v", err)
	}
	defer reloaded.Close()

	if got, want := reloaded.lastModifiedTsSeconds, newWriteNs/uint64(time.Second); got != want {
		t.Errorf("TTL clock recovered as %d, want the newest write at %d", got, want)
	}
	if reloaded.expired(contentSize, 1024*1024) {
		t.Error("a volume overwritten a minute ago must not be expired after a vacuum and reload")
	}
}

// TestVolumeTtlClockDeclinesUnaffordableScan covers the budget the vacuumed
// path runs under. Reading a subset of a key-ordered volume's writes could
// recover a timestamp older than the newest write and expire live data, so a
// scan that does not fit has to leave the clock on the mtime instead.
func TestVolumeTtlClockDeclinesUnaffordableScan(t *testing.T) {
	dir := t.TempDir()
	ttl, err := needle.ReadTTL("5m")
	if err != nil {
		t.Fatalf("read ttl: %v", err)
	}

	v, err := NewVolume(dir, dir, "", 1, NeedleMapInMemory, &super_block.ReplicaPlacement{}, ttl, 0, needle.GetCurrentVersion(), 0, 0)
	if err != nil {
		t.Fatalf("volume creation: %v", err)
	}
	oldWriteNs := uint64(time.Now().Add(-2 * time.Hour).UnixNano())
	for i := 1; i <= 3; i++ {
		n := newRandomNeedle(uint64(i))
		offset, _, _, err := v.writeNeedle2(n, true, false, false)
		if err != nil {
			t.Fatalf("write needle %d: %v", i, err)
		}
		backdateAppendAtNs(t, v, int64(offset), n.Size, oldWriteNs)
	}
	if err := v.CompactByIndex(nil); err != nil {
		t.Fatalf("compact: %v", err)
	}
	if err := v.CommitCompact(); err != nil {
		t.Fatalf("commit compact: %v", err)
	}
	contentSize := v.ContentSize()
	v.Close()

	defer func(budget int) { vacuumedLastWriteScanEntries = budget }(vacuumedLastWriteScanEntries)
	vacuumedLastWriteScanEntries = 2

	reloaded, err := NewVolume(dir, dir, "", 1, NeedleMapInMemory, &super_block.ReplicaPlacement{}, ttl, 0, needle.GetCurrentVersion(), 0, 0)
	if err != nil {
		t.Fatalf("reload: %v", err)
	}
	defer reloaded.Close()

	if reloaded.lastModifiedTsSeconds == oldWriteNs/uint64(time.Second) {
		t.Error("a scan that ran out of budget must not report a partial maximum as the last write")
	}
	if reloaded.expired(contentSize, 1024*1024) {
		t.Error("declining the scan must leave the volume on its mtime, not expire it")
	}
}

// TestVolumeExpireAtSecCountsFromLastWrite guards the destroy time an EC volume
// is reclaimed on (erasure_coding.EcVolume.IsTimeToDestroy). It was recomputed
// as now+TTL on every .vif write, so a read-only mark, a tier upload or an EC
// encode handed an already expiring volume another full TTL.
func TestVolumeExpireAtSecCountsFromLastWrite(t *testing.T) {
	dir := t.TempDir()
	ttl, err := needle.ReadTTL("5m")
	if err != nil {
		t.Fatalf("read ttl: %v", err)
	}

	v, err := NewVolume(dir, dir, "", 1, NeedleMapInMemory, &super_block.ReplicaPlacement{}, ttl, 0, needle.GetCurrentVersion(), 0, 0)
	if err != nil {
		t.Fatalf("volume creation: %v", err)
	}
	defer v.Close()

	// A volume with nothing written yet has no last write to count from, and
	// must not land in 1970 with its data due for destruction on sight.
	if got := v.GetVolumeInfo().ExpireAtSec; got < uint64(time.Now().Unix()) {
		t.Errorf("a fresh volume expires at %d, already in the past", got)
	}

	if _, _, _, err := v.writeNeedle2(newRandomNeedle(1), true, false, false); err != nil {
		t.Fatalf("write needle: %v", err)
	}
	v.lastModifiedTsSeconds = uint64(time.Now().Add(-time.Hour).Unix())
	want := v.lastModifiedTsSeconds + ttl.ToSeconds()

	for i := 0; i < 2; i++ {
		if err := v.SaveVolumeInfo(); err != nil {
			t.Fatalf("save .vif: %v", err)
		}
		if got := v.GetVolumeInfo().ExpireAtSec; got != want {
			t.Fatalf(".vif save %d put ExpireAtSec at %d, want %d counted from the last write", i, got, want)
		}
	}
}

func backdateAppendAtNs(t *testing.T, v *Volume, offset int64, size types.Size, appendAtNs uint64) {
	t.Helper()
	stamp := make([]byte, types.TimestampSize)
	util.Uint64toBytes(stamp, appendAtNs)
	tsOffset := offset + types.NeedleHeaderSize + int64(size) + needle.NeedleChecksumSize
	if _, err := v.DataBackend.WriteAt(stamp, tsOffset); err != nil {
		t.Fatalf("backdate the needle at offset %d: %v", offset, err)
	}
}