package archiver

import (
	"bytes"
	"context"
	"errors"
	"io"
	"testing"
	"time"

	"git.unkin.net/unkin/logarchiver/internal/batcher"
	"git.unkin.net/unkin/logarchiver/internal/crypto"
	"git.unkin.net/unkin/logarchiver/internal/index"
	"github.com/ProtonMail/go-crypto/openpgp"
	"github.com/ProtonMail/go-crypto/openpgp/armor"
)

// --- fakes ---

type fakeStore struct {
	bucket  string
	objects map[string][]byte
	failPut bool
}

func newFakeStore() *fakeStore {
	return &fakeStore{bucket: "test-bucket", objects: map[string][]byte{}}
}

func (f *fakeStore) Put(_ context.Context, key string, body io.Reader, _ int64) error {
	if f.failPut {
		return errors.New("simulated s3 failure")
	}
	data, err := io.ReadAll(body)
	if err != nil {
		return err
	}
	f.objects[key] = data
	return nil
}
func (f *fakeStore) Get(_ context.Context, key string) (io.ReadCloser, error) {
	data, ok := f.objects[key]
	if !ok {
		return nil, errors.New("not found")
	}
	return io.NopCloser(bytes.NewReader(data)), nil
}
func (f *fakeStore) List(_ context.Context, _ string) ([]string, error) { return nil, nil }
func (f *fakeStore) Bucket() string                                     { return f.bucket }

type fakeIndex struct {
	rows []index.Row
	fail bool
}

func (f *fakeIndex) Insert(_ context.Context, row index.Row) error {
	if f.fail {
		return errors.New("simulated index failure")
	}
	f.rows = append(f.rows, row)
	return nil
}
func (f *fakeIndex) Search(context.Context, index.SearchQuery) ([]index.Result, error) {
	return nil, nil
}
func (f *fakeIndex) InitSchema(context.Context) error { return nil }
func (f *fakeIndex) Ping(context.Context) error       { return nil }
func (f *fakeIndex) Close() error                     { return nil }

func testPubkey(t *testing.T) *crypto.PublicKey {
	t.Helper()
	ent, err := openpgp.NewEntity("t", "", "t@unkin.net", nil)
	if err != nil {
		t.Fatalf("NewEntity: %v", err)
	}
	var buf bytes.Buffer
	w, _ := armor.Encode(&buf, openpgp.PublicKeyType, nil)
	_ = ent.Serialize(w)
	_ = w.Close()
	pk, err := crypto.LoadPublicKey(buf.Bytes())
	if err != nil {
		t.Fatalf("LoadPublicKey: %v", err)
	}
	return pk
}

func newTestArchiver(t *testing.T, store *fakeStore, idx index.Index) *Archiver {
	t.Helper()
	pk := testPubkey(t)
	kb, _ := NewKeyBuilder("archive/{{.Subject}}/{{.Year}}/{{.Month}}/{{.Day}}/")
	prov, err := NewPubkeyProvider(context.Background(), func(context.Context) (*crypto.PublicKey, error) {
		return pk, nil
	})
	if err != nil {
		t.Fatalf("provider: %v", err)
	}
	a, err := New(Options{
		Keys:      kb,
		Pubkeys:   prov,
		Store:     store,
		Index:     idx,
		KeyName:   "logarchive",
		FrameSize: 4096,
	})
	if err != nil {
		t.Fatalf("New: %v", err)
	}
	return a
}

func sampleBatch() *batcher.Batch {
	ts := time.Date(2026, 7, 27, 1, 0, 0, 0, time.UTC)
	return &batcher.Batch{
		Subject: "logs.k8s.vault.audit",
		Items: []batcher.Item{
			{Subject: "logs.k8s.vault.audit", Host: "node-1", Timestamp: ts, HasTS: true, Raw: []byte(`{"host":"node-1","message":"a"}`)},
			{Subject: "logs.k8s.vault.audit", Host: "node-2", Timestamp: ts.Add(time.Hour), HasTS: true, Raw: []byte(`{"host":"node-2","message":"b"}`)},
		},
		RawBytes: 62,
	}
}

func TestStoreSuccessWritesObjectAndIndex(t *testing.T) {
	store := newFakeStore()
	idx := &fakeIndex{}
	a := newTestArchiver(t, store, idx)

	res, err := a.Store(context.Background(), sampleBatch())
	if err != nil {
		t.Fatalf("Store: %v", err)
	}
	if res.Events != 2 {
		t.Errorf("events = %d", res.Events)
	}
	if len(store.objects) != 1 {
		t.Fatalf("expected 1 stored object, got %d", len(store.objects))
	}
	// Stored bytes must be a valid LARC1 container.
	obj := store.objects[res.ObjectKey]
	if _, _, err := crypto.ReadHeader(bytes.NewReader(obj)); err != nil {
		t.Errorf("stored object is not a valid container: %v", err)
	}
	if len(idx.rows) != 1 {
		t.Fatalf("expected 1 index row, got %d", len(idx.rows))
	}
	row := idx.rows[0]
	if row.Subject != "logs.k8s.vault.audit" {
		t.Errorf("row subject = %q", row.Subject)
	}
	if row.EventCount != 2 {
		t.Errorf("row event_count = %d", row.EventCount)
	}
	if len(row.Hosts) != 2 || row.Hosts[0] != "node-1" || row.Hosts[1] != "node-2" {
		t.Errorf("row hosts = %v", row.Hosts)
	}
	if row.Bucket != "test-bucket" {
		t.Errorf("row bucket = %q", row.Bucket)
	}
	if row.ContainerFormat != "LARC1" || row.Compression != "zstd" {
		t.Errorf("row metadata wrong: %+v", row)
	}
	if row.KeyFingerprint == "" {
		t.Errorf("row missing key fingerprint")
	}
}

// The central at-least-once property: if S3 fails, Store errors and NOTHING is
// written to the index, so the caller will not ack.
func TestStoreS3FailureNoIndexNoAck(t *testing.T) {
	store := newFakeStore()
	store.failPut = true
	idx := &fakeIndex{}
	a := newTestArchiver(t, store, idx)

	if _, err := a.Store(context.Background(), sampleBatch()); err == nil {
		t.Fatalf("expected error when S3 put fails")
	}
	if len(idx.rows) != 0 {
		t.Errorf("index written despite S3 failure: %d rows", len(idx.rows))
	}
	if len(store.objects) != 0 {
		t.Errorf("object recorded despite S3 failure")
	}
}

// If indexing fails after the S3 put, Store still errors (so no ack); the object
// exists but is unindexed — acceptable, it will be re-stored on redelivery.
func TestStoreIndexFailureErrors(t *testing.T) {
	store := newFakeStore()
	idx := &fakeIndex{fail: true}
	a := newTestArchiver(t, store, idx)

	if _, err := a.Store(context.Background(), sampleBatch()); err == nil {
		t.Fatalf("expected error when index insert fails")
	}
	if len(store.objects) != 1 {
		t.Errorf("object should still be in S3 (orphan), got %d", len(store.objects))
	}
}

func TestStoreNilIndexOK(t *testing.T) {
	store := newFakeStore()
	a := newTestArchiver(t, store, nil)
	if _, err := a.Store(context.Background(), sampleBatch()); err != nil {
		t.Fatalf("Store with nil index: %v", err)
	}
	if len(store.objects) != 1 {
		t.Errorf("expected object stored")
	}
}

func TestStoreEmptyBatchNoop(t *testing.T) {
	store := newFakeStore()
	a := newTestArchiver(t, store, &fakeIndex{})
	res, err := a.Store(context.Background(), &batcher.Batch{Subject: "s"})
	if err != nil {
		t.Fatalf("empty batch: %v", err)
	}
	if res.ObjectKey != "" || len(store.objects) != 0 {
		t.Errorf("empty batch should store nothing")
	}
}