package storage

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"io"
	"os"
	"path/filepath"
	"testing"
	"time"
)

func TestCreateStoresGzipAndOpenIsTransparent(t *testing.T) {
	t.Parallel()

	store, err := NewFilesystemStore(filepath.Join(t.TempDir(), "data"))
	if err != nil {
		t.Fatalf("NewFilesystemStore() error = %v", err)
	}

	original := bytes.Repeat([]byte("hello scratch "), 1024)
	meta, err := store.Create(context.Background(), bytes.NewReader(original), "text/plain; charset=utf-8", time.Hour)
	if err != nil {
		t.Fatalf("Create() error = %v", err)
	}
	if meta.Size != int64(len(original)) {
		t.Fatalf("meta.Size = %d, want %d", meta.Size, len(original))
	}

	onDisk, err := os.ReadFile(meta.FilePath)
	if err != nil {
		t.Fatalf("ReadFile() error = %v", err)
	}
	if len(onDisk) < 2 || onDisk[0] != 0x1f || onDisk[1] != 0x8b {
		t.Fatalf("stored file does not have gzip header")
	}

	reader, _, err := store.Open(meta.ID)
	if err != nil {
		t.Fatalf("Open() error = %v", err)
	}
	defer reader.Close()
	got, err := io.ReadAll(reader)
	if err != nil {
		t.Fatalf("ReadAll() error = %v", err)
	}
	if !bytes.Equal(got, original) {
		t.Fatalf("open content mismatch: got %d bytes, want %d", len(got), len(original))
	}
}

func TestGetDeleteAndNotFound(t *testing.T) {
	t.Parallel()

	store, err := NewFilesystemStore(filepath.Join(t.TempDir(), "data"))
	if err != nil {
		t.Fatalf("NewFilesystemStore() error = %v", err)
	}
	meta, err := store.Create(context.Background(), bytes.NewReader([]byte("hello")), "text/plain", time.Hour)
	if err != nil {
		t.Fatalf("Create() error = %v", err)
	}
	if _, err := store.Get(meta.ID); err != nil {
		t.Fatalf("Get() error = %v", err)
	}
	if err := store.Delete(meta.ID); err != nil {
		t.Fatalf("Delete() error = %v", err)
	}
	if _, err := store.Get(meta.ID); !errors.Is(err, ErrNotFound) {
		t.Fatalf("Get() error = %v, want ErrNotFound", err)
	}
	if err := store.Delete(meta.ID); !errors.Is(err, ErrNotFound) {
		t.Fatalf("Delete() error = %v, want ErrNotFound", err)
	}
}

func TestDeleteExpired(t *testing.T) {
	t.Parallel()

	store, err := NewFilesystemStore(filepath.Join(t.TempDir(), "data"))
	if err != nil {
		t.Fatalf("NewFilesystemStore() error = %v", err)
	}
	expired, err := store.Create(context.Background(), bytes.NewReader([]byte("expired")), "text/plain", -time.Second)
	if err != nil {
		t.Fatalf("Create expired() error = %v", err)
	}
	active, err := store.Create(context.Background(), bytes.NewReader([]byte("active")), "text/plain", time.Hour)
	if err != nil {
		t.Fatalf("Create active() error = %v", err)
	}
	deleted, err := store.DeleteExpired(time.Now().UTC())
	if err != nil {
		t.Fatalf("DeleteExpired() error = %v", err)
	}
	if deleted != 1 {
		t.Fatalf("DeleteExpired() = %d, want 1", deleted)
	}
	if _, err := store.Get(expired.ID); !errors.Is(err, ErrNotFound) {
		t.Fatalf("expired Get() error = %v, want ErrNotFound", err)
	}
	if _, err := store.Get(active.ID); err != nil {
		t.Fatalf("active Get() error = %v", err)
	}
}

func TestOpenInvalidGzipFails(t *testing.T) {
	t.Parallel()

	store, err := NewFilesystemStore(filepath.Join(t.TempDir(), "data"))
	if err != nil {
		t.Fatalf("NewFilesystemStore() error = %v", err)
	}
	id := "deadbeefdeadbeefdeadbeef"
	badPath := filepath.Join(store.filesDir, id)
	if err := os.WriteFile(badPath, []byte("not-gzip"), 0o644); err != nil {
		t.Fatalf("WriteFile() error = %v", err)
	}
	store.metadata[id] = Metadata{
		ID:          id,
		FilePath:    badPath,
		CreatedAt:   time.Now().UTC(),
		ExpiresAt:   time.Now().UTC().Add(time.Hour),
		ContentType: "text/plain",
		Size:        int64(len("not-gzip")),
	}
	if err := store.persistLocked(); err != nil {
		t.Fatalf("persistLocked() error = %v", err)
	}
	if _, _, err := store.Open(id); err == nil {
		t.Fatalf("Open() error = nil, want gzip reader error")
	}
}

func TestNewFilesystemStoreInvalidIndex(t *testing.T) {
	t.Parallel()

	root := t.TempDir()
	scratches := filepath.Join(root, filesDirName)
	if err := os.MkdirAll(scratches, 0o755); err != nil {
		t.Fatalf("MkdirAll() error = %v", err)
	}
	if err := os.WriteFile(filepath.Join(root, indexFilename), []byte("{bad"), 0o644); err != nil {
		t.Fatalf("WriteFile() error = %v", err)
	}
	if _, err := NewFilesystemStore(root); err == nil {
		t.Fatalf("NewFilesystemStore() error = nil, want invalid index error")
	}
}

func TestNewFilesystemStoreReconcileOnStartup(t *testing.T) {
	t.Parallel()

	root := t.TempDir()
	scratches := filepath.Join(root, filesDirName)
	if err := os.MkdirAll(scratches, 0o755); err != nil {
		t.Fatalf("MkdirAll() error = %v", err)
	}
	keepID := "aaaaaaaaaaaaaaaaaaaaaaaa"
	missingID := "bbbbbbbbbbbbbbbbbbbbbbbb"
	expiredID := "cccccccccccccccccccccccc"
	keepPath := filepath.Join(scratches, keepID)
	expiredPath := filepath.Join(scratches, expiredID)
	if err := os.WriteFile(keepPath, []byte{0x1f, 0x8b, 0x08, 0x00}, 0o644); err != nil {
		t.Fatalf("WriteFile keep error = %v", err)
	}
	if err := os.WriteFile(expiredPath, []byte{0x1f, 0x8b, 0x08, 0x00}, 0o644); err != nil {
		t.Fatalf("WriteFile expired error = %v", err)
	}

	meta := map[string]Metadata{
		keepID: {
			ID:          keepID,
			FilePath:    keepPath,
			CreatedAt:   time.Now().UTC(),
			ExpiresAt:   time.Now().UTC().Add(time.Hour),
			ContentType: "text/plain",
			Size:        1,
		},
		missingID: {
			ID:          missingID,
			FilePath:    filepath.Join(scratches, missingID),
			CreatedAt:   time.Now().UTC(),
			ExpiresAt:   time.Now().UTC().Add(time.Hour),
			ContentType: "text/plain",
			Size:        1,
		},
		expiredID: {
			ID:          expiredID,
			FilePath:    expiredPath,
			CreatedAt:   time.Now().UTC(),
			ExpiresAt:   time.Now().UTC().Add(-time.Minute),
			ContentType: "text/plain",
			Size:        1,
		},
	}
	payload, err := json.Marshal(meta)
	if err != nil {
		t.Fatalf("json.Marshal() error = %v", err)
	}
	if err := os.WriteFile(filepath.Join(root, indexFilename), payload, 0o644); err != nil {
		t.Fatalf("WriteFile index error = %v", err)
	}

	store, err := NewFilesystemStore(root)
	if err != nil {
		t.Fatalf("NewFilesystemStore() error = %v", err)
	}
	if _, err := store.Get(keepID); err != nil {
		t.Fatalf("keep entry missing: %v", err)
	}
	if _, err := store.Get(missingID); !errors.Is(err, ErrNotFound) {
		t.Fatalf("missing entry error = %v, want ErrNotFound", err)
	}
	if _, err := store.Get(expiredID); !errors.Is(err, ErrNotFound) {
		t.Fatalf("expired entry error = %v, want ErrNotFound", err)
	}
}

type errCloser struct{}

func (errCloser) Close() error { return errors.New("close failed") }

func TestCombinedReadCloserClosePropagatesFirstError(t *testing.T) {
	t.Parallel()

	c := &combinedReadCloser{
		reader:  bytes.NewReader([]byte("ok")),
		closers: []io.Closer{errCloser{}, errCloser{}},
	}
	if err := c.Close(); err == nil {
		t.Fatalf("Close() error = nil, want non-nil")
	}
}

type failingReader struct{}

func (failingReader) Read(_ []byte) (int, error) { return 0, errors.New("boom") }

func TestCreateRollbackOnPersistFailure(t *testing.T) {
	t.Parallel()

	store, err := NewFilesystemStore(filepath.Join(t.TempDir(), "data"))
	if err != nil {
		t.Fatalf("NewFilesystemStore() error = %v", err)
	}

	badIndexDir := filepath.Join(t.TempDir(), "index-dir")
	if err := os.MkdirAll(badIndexDir, 0o755); err != nil {
		t.Fatalf("MkdirAll() error = %v", err)
	}
	store.index = badIndexDir

	if _, err := store.Create(context.Background(), bytes.NewReader([]byte("x")), "text/plain", time.Hour); err == nil {
		t.Fatalf("Create() error = nil, want persist failure")
	}
	if len(store.metadata) != 0 {
		t.Fatalf("metadata should be rolled back on persist failure")
	}
}

func TestCreateReaderFailure(t *testing.T) {
	t.Parallel()

	store, err := NewFilesystemStore(filepath.Join(t.TempDir(), "data"))
	if err != nil {
		t.Fatalf("NewFilesystemStore() error = %v", err)
	}
	if _, err := store.Create(context.Background(), failingReader{}, "text/plain", time.Hour); err == nil {
		t.Fatalf("Create() error = nil, want reader failure")
	}
}

func TestDeletePersistFailureRestoresEntry(t *testing.T) {
	t.Parallel()

	store, err := NewFilesystemStore(filepath.Join(t.TempDir(), "data"))
	if err != nil {
		t.Fatalf("NewFilesystemStore() error = %v", err)
	}
	meta, err := store.Create(context.Background(), bytes.NewReader([]byte("hello")), "text/plain", time.Hour)
	if err != nil {
		t.Fatalf("Create() error = %v", err)
	}

	badIndexDir := filepath.Join(t.TempDir(), "index-dir")
	if err := os.MkdirAll(badIndexDir, 0o755); err != nil {
		t.Fatalf("MkdirAll() error = %v", err)
	}
	store.index = badIndexDir

	if err := store.Delete(meta.ID); err == nil {
		t.Fatalf("Delete() error = nil, want persist failure")
	}
	if _, err := store.Get(meta.ID); err != nil {
		t.Fatalf("entry should be restored after delete persist failure: %v", err)
	}
}

func TestDeleteRemoveFailure(t *testing.T) {
	t.Parallel()

	store, err := NewFilesystemStore(filepath.Join(t.TempDir(), "data"))
	if err != nil {
		t.Fatalf("NewFilesystemStore() error = %v", err)
	}

	nonEmptyDir := filepath.Join(t.TempDir(), "non-empty")
	if err := os.MkdirAll(nonEmptyDir, 0o755); err != nil {
		t.Fatalf("MkdirAll() error = %v", err)
	}
	if err := os.WriteFile(filepath.Join(nonEmptyDir, "child"), []byte("x"), 0o644); err != nil {
		t.Fatalf("WriteFile() error = %v", err)
	}
	id := "dddddddddddddddddddddddd"
	store.metadata[id] = Metadata{
		ID:          id,
		FilePath:    nonEmptyDir,
		CreatedAt:   time.Now().UTC(),
		ExpiresAt:   time.Now().UTC().Add(time.Hour),
		ContentType: "text/plain",
		Size:        1,
	}
	if err := store.persistLocked(); err != nil {
		t.Fatalf("persistLocked() error = %v", err)
	}
	if err := store.Delete(id); err == nil {
		t.Fatalf("Delete() error = nil, want remove failure")
	}
}

func TestDeleteExpiredPersistFailureRestoresEntries(t *testing.T) {
	t.Parallel()

	store, err := NewFilesystemStore(filepath.Join(t.TempDir(), "data"))
	if err != nil {
		t.Fatalf("NewFilesystemStore() error = %v", err)
	}
	meta, err := store.Create(context.Background(), bytes.NewReader([]byte("expired")), "text/plain", -time.Second)
	if err != nil {
		t.Fatalf("Create() error = %v", err)
	}

	badIndexDir := filepath.Join(t.TempDir(), "index-dir")
	if err := os.MkdirAll(badIndexDir, 0o755); err != nil {
		t.Fatalf("MkdirAll() error = %v", err)
	}
	store.index = badIndexDir

	if _, err := store.DeleteExpired(time.Now().UTC()); err == nil {
		t.Fatalf("DeleteExpired() error = nil, want persist failure")
	}
	if _, err := store.Get(meta.ID); err != nil {
		t.Fatalf("entry should be restored after DeleteExpired persist failure: %v", err)
	}
}

func TestDeleteExpiredRemoveFailure(t *testing.T) {
	t.Parallel()

	store, err := NewFilesystemStore(filepath.Join(t.TempDir(), "data"))
	if err != nil {
		t.Fatalf("NewFilesystemStore() error = %v", err)
	}
	nonEmptyDir := filepath.Join(t.TempDir(), "expired-non-empty")
	if err := os.MkdirAll(nonEmptyDir, 0o755); err != nil {
		t.Fatalf("MkdirAll() error = %v", err)
	}
	if err := os.WriteFile(filepath.Join(nonEmptyDir, "child"), []byte("x"), 0o644); err != nil {
		t.Fatalf("WriteFile() error = %v", err)
	}
	id := "eeeeeeeeeeeeeeeeeeeeeeee"
	store.metadata[id] = Metadata{
		ID:          id,
		FilePath:    nonEmptyDir,
		CreatedAt:   time.Now().UTC(),
		ExpiresAt:   time.Now().UTC().Add(-time.Second),
		ContentType: "text/plain",
		Size:        1,
	}
	if err := store.persistLocked(); err != nil {
		t.Fatalf("persistLocked() error = %v", err)
	}
	if _, err := store.DeleteExpired(time.Now().UTC()); err == nil {
		t.Fatalf("DeleteExpired() error = nil, want remove failure")
	}
}

func TestNewFilesystemStoreFailsWhenDataDirIsFile(t *testing.T) {
	t.Parallel()

	tmp := t.TempDir()
	filePath := filepath.Join(tmp, "not-dir")
	if err := os.WriteFile(filePath, []byte("x"), 0o644); err != nil {
		t.Fatalf("WriteFile() error = %v", err)
	}
	if _, err := NewFilesystemStore(filePath); err == nil {
		t.Fatalf("NewFilesystemStore() error = nil, want mkdir failure")
	}
}