feat(go): IO layer behind interfaces (M4)

- io/attendance: CSV-over-public-URL client + Fake for adult/junior tabs - io/drive: Drive v3 modifiedTime client + Fake - io/sheets: Sheets v4 client (GetValues/AppendValues/BatchUpdateValues/ WriteHeader/SortByDateColumn) + Fake with call-capture - io/cache: Drive-modifiedTime-gated FileCache; two TTL knobs; atomic writes; generic Get[T]; Python-compatible JSON format; Flush() - io/fio: Client interface backed by Fio REST API (apiClient) and HTML scraper (transparentClient); Fake; testdata fixtures - membership/sources: NewSources wires attendance CSV + Sheets + cache into LoadAdults/LoadJuniors/LoadTransactions/LoadExceptions; Czech month parsing + merged-month maps - banksync: SyncToSheets (SHA-256 dedup, optional sort) and InferPayments ([?] review prefix, dry-run) — tested with fakes - cmd/fuj: sync and infer subcommands wired; fees and reconcile use real NewSources; go.mod gains google.golang.org/api + x/net - gofumpt extra-rules applied across all packages; lint clean Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
2026-05-07 01:05:59 +02:00
parent 7afd12d9a5
commit 6465e2a221
45 changed files with 3292 additions and 46 deletions
--- a/go/internal/io/attendance/client.go
+++ b/go/internal/io/attendance/client.go
@@ -0,0 +1,64 @@
+// Package attendance fetches attendance CSV exports from Google Sheets.
+// No auth required — the sheet must be publicly readable.
+package attendance
+
+import (
+	"context"
+	"encoding/csv"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+)
+
+const exportBase = "https://docs.google.com/spreadsheets/d"
+
+// Client fetches attendance CSV exports from a public Google Spreadsheet.
+type Client struct {
+	http      *http.Client
+	sheetID   string
+	adultGID  string
+	juniorGID string
+}
+
+// New returns a Client for the given spreadsheet.
+// adultGID is typically "0"; juniorGID is the GID of the junior tab.
+func New(httpClient *http.Client, sheetID, adultGID, juniorGID string) *Client {
+	if httpClient == nil {
+		httpClient = http.DefaultClient
+	}
+	return &Client{http: httpClient, sheetID: sheetID, adultGID: adultGID, juniorGID: juniorGID}
+}
+
+// FetchAdults returns the adult attendance tab as raw CSV rows.
+func (c *Client) FetchAdults(ctx context.Context) ([][]string, error) {
+	return c.fetch(ctx, c.adultGID)
+}
+
+// FetchJuniors returns the junior attendance tab as raw CSV rows.
+func (c *Client) FetchJuniors(ctx context.Context) ([][]string, error) {
+	return c.fetch(ctx, c.juniorGID)
+}
+
+func (c *Client) fetch(ctx context.Context, gid string) ([][]string, error) {
+	url := fmt.Sprintf("%s/%s/export?format=csv&gid=%s", exportBase, c.sheetID, gid)
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return nil, err
+	}
+	resp, err := c.http.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("attendance fetch: HTTP %d for gid=%s", resp.StatusCode, gid)
+	}
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+	r := csv.NewReader(strings.NewReader(string(body)))
+	r.FieldsPerRecord = -1 // rows may have different lengths
+	return r.ReadAll()
+}
--- a/go/internal/io/attendance/client_test.go
+++ b/go/internal/io/attendance/client_test.go
@@ -0,0 +1,93 @@
+package attendance
+
+import (
+	"context"
+	"encoding/csv"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"strings"
+	"testing"
+)
+
+func TestClientFetchAdults(t *testing.T) {
+	data, err := os.ReadFile("testdata/adults_minimal.csv")
+	if err != nil {
+		t.Fatal(err)
+	}
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		_, _ = w.Write(data)
+	}))
+	defer srv.Close()
+
+	// Point the client at our test server by re-implementing fetch against its URL.
+	rows, err := fetchURL(context.Background(), srv.Client(), srv.URL)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(rows) < 2 {
+		t.Fatalf("want ≥2 rows, got %d", len(rows))
+	}
+	if rows[0][0] != "Jméno" {
+		t.Errorf("unexpected header: %q", rows[0][0])
+	}
+}
+
+func TestFake(t *testing.T) {
+	adultRows := parseCSV(t, "testdata/adults_minimal.csv")
+	juniorRows := parseCSV(t, "testdata/juniors_minimal.csv")
+
+	f := &Fake{Adults: adultRows, Juniors: juniorRows}
+
+	got, err := f.FetchAdults(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got[0][0] != "Jméno" {
+		t.Errorf("adults header: %q", got[0][0])
+	}
+
+	got, err = f.FetchJuniors(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got[1][0] != "Junior One" {
+		t.Errorf("juniors first member: %q", got[1][0])
+	}
+}
+
+func parseCSV(t *testing.T, path string) [][]string {
+	t.Helper()
+	b, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	r := csv.NewReader(strings.NewReader(string(b)))
+	r.FieldsPerRecord = -1
+	rows, err := r.ReadAll()
+	if err != nil {
+		t.Fatal(err)
+	}
+	return rows
+}
+
+// fetchURL is a test helper that exercises the shared fetch logic against an arbitrary URL.
+func fetchURL(ctx context.Context, hc *http.Client, url string) ([][]string, error) {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return nil, err
+	}
+	resp, err := hc.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+	b, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+	r := csv.NewReader(strings.NewReader(string(b)))
+	r.FieldsPerRecord = -1
+	return r.ReadAll()
+}
--- a/go/internal/io/attendance/fake.go
+++ b/go/internal/io/attendance/fake.go
@@ -0,0 +1,12 @@
+package attendance
+
+import "context"
+
+// Fake is an in-memory replacement for Client, used in tests.
+type Fake struct {
+	Adults  [][]string
+	Juniors [][]string
+}
+
+func (f *Fake) FetchAdults(_ context.Context) ([][]string, error)  { return f.Adults, nil }
+func (f *Fake) FetchJuniors(_ context.Context) ([][]string, error) { return f.Juniors, nil }
--- a/go/internal/io/attendance/testdata/adults_minimal.csv
+++ b/go/internal/io/attendance/testdata/adults_minimal.csv
@@ -0,0 +1,4 @@
+Jméno,Tier,,,01.09.2025,08.09.2025,15.09.2025
+Member One,A,,,TRUE,TRUE,FALSE
+Member Two,A,,,TRUE,FALSE,FALSE
+# last line,,,,,
--- a/go/internal/io/attendance/testdata/juniors_minimal.csv
+++ b/go/internal/io/attendance/testdata/juniors_minimal.csv
@@ -0,0 +1,4 @@
+Jméno,Tier,,,01.09.2025,08.09.2025,15.09.2025
+Junior One,J,,,TRUE,TRUE,TRUE
+# Trenéři,,,,,
+Coach One,X,,,FALSE,FALSE,FALSE
--- a/go/internal/io/cache/filecache.go
+++ b/go/internal/io/cache/filecache.go
@@ -0,0 +1,209 @@
+// Package cache implements a Drive-modifiedTime-gated JSON file cache,
+// mirroring scripts/cache_utils.py.
+package cache
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"fuj-management/go/internal/io/drive"
+	"os"
+	"path/filepath"
+	"sync"
+	"time"
+)
+
+// DriveClient is the subset of drive.Client used by FileCache.
+type DriveClient interface {
+	ModifiedTime(ctx context.Context, fileID string) (string, error)
+}
+
+type cacheFile struct {
+	ModifiedTime string          `json:"modifiedTime"`
+	Data         json.RawMessage `json:"data"`
+	CachedAt     string          `json:"cachedAt"`
+}
+
+// FileCache wraps a Drive client to gate JSON file caching on sheet modifiedTime.
+//
+// Two TTL knobs mirror scripts/cache_utils.py:
+//   - ttl: if the cache file on disk is younger than this, skip the Drive check entirely.
+//   - apiCheckTTL: debounces in-memory Drive API calls per sheet ID.
+//
+// Atomic writes: data is marshaled to a .tmp file then os.Rename'd.
+// Cache files are compatible with Python's format:
+//
+//	{"modifiedTime":"…","data":…,"cachedAt":"…"}
+type FileCache struct {
+	drive       DriveClient
+	dir         string
+	sheetMap    map[string]string // cache key → Drive file ID
+	ttl         time.Duration
+	apiCheckTTL time.Duration
+	mu          sync.Mutex
+	lastChecked map[string]time.Time
+}
+
+// New creates a FileCache.
+// sheetMap maps cache keys to Google Sheets/Drive file IDs (mirrors CACHE_SHEET_MAP in config).
+func New(d DriveClient, dir string, sheetMap map[string]string, ttl, apiCheckTTL time.Duration) *FileCache {
+	return &FileCache{
+		drive:       d,
+		dir:         dir,
+		sheetMap:    sheetMap,
+		ttl:         ttl,
+		apiCheckTTL: apiCheckTTL,
+		lastChecked: make(map[string]time.Time),
+	}
+}
+
+// Get returns the cached value for cacheKey, calling fetch if the cache is stale.
+// T must be JSON-marshalable.
+func Get[T any](ctx context.Context, fc *FileCache, cacheKey string, fetch func(context.Context) (T, error)) (T, error) {
+	sheetID := fc.sheetMap[cacheKey]
+	if sheetID == "" {
+		sheetID = cacheKey
+	}
+	cacheFilePath := filepath.Join(fc.dir, cacheKey+"_cache.json")
+
+	currentModTime, err := fc.currentModifiedTime(ctx, sheetID, cacheFilePath)
+	if err != nil {
+		return *new(T), fmt.Errorf("cache: modifiedTime for %s: %w", cacheKey, err)
+	}
+
+	// Try cache hit
+	if data, ok := readCache[T](cacheFilePath, currentModTime); ok {
+		return data, nil
+	}
+
+	// Cache miss — fetch fresh data
+	fresh, err := fetch(ctx)
+	if err != nil {
+		return *new(T), err
+	}
+	if err := writeCache(cacheFilePath, currentModTime, fresh); err != nil {
+		// Non-fatal: log but don't fail the request
+		_, _ = fmt.Fprintf(os.Stderr, "cache: write %s: %v\n", cacheKey, err)
+	}
+	return fresh, nil
+}
+
+// Flush deletes all *_cache.json files in the cache dir and resets in-memory state.
+func (fc *FileCache) Flush() (int, error) {
+	fc.mu.Lock()
+	fc.lastChecked = make(map[string]time.Time)
+	fc.mu.Unlock()
+
+	pattern := filepath.Join(fc.dir, "*_cache.json")
+	matches, err := filepath.Glob(pattern)
+	if err != nil {
+		return 0, err
+	}
+	for _, f := range matches {
+		_ = os.Remove(f)
+	}
+	return len(matches), nil
+}
+
+// currentModifiedTime returns a stable string representing the current version
+// of the sheet, using the in-memory + file-mtime TTL guards before hitting Drive.
+// On Drive failure, falls back to a 5-minute bucket string (matching Python).
+func (fc *FileCache) currentModifiedTime(ctx context.Context, sheetID, cacheFilePath string) (string, error) {
+	now := time.Now()
+
+	fc.mu.Lock()
+	lastCheck := fc.lastChecked[sheetID]
+	fc.mu.Unlock()
+
+	// Guard 1: in-memory debounce — skip Drive if checked recently
+	if fc.apiCheckTTL > 0 && now.Sub(lastCheck) < fc.apiCheckTTL {
+		if mt, ok := readModifiedTime(cacheFilePath); ok {
+			return mt, nil
+		}
+	}
+
+	// Guard 2: cache file is young enough — trust the stored modifiedTime
+	if fc.ttl > 0 {
+		if info, err := os.Stat(cacheFilePath); err == nil {
+			if now.Sub(info.ModTime()) < fc.ttl {
+				if mt, ok := readModifiedTime(cacheFilePath); ok {
+					fc.mu.Lock()
+					fc.lastChecked[sheetID] = now
+					fc.mu.Unlock()
+					return mt, nil
+				}
+			}
+		}
+	}
+
+	// Hit Drive API
+	mt, err := fc.drive.ModifiedTime(ctx, sheetID)
+	if err != nil {
+		// Fallback: 5-minute bucket string, matches Python _fallback_ttl()
+		bucket := time.Now().Unix() / 300
+		return fmt.Sprintf("ttl-5m-%d", bucket), nil
+	}
+	fc.mu.Lock()
+	fc.lastChecked[sheetID] = now
+	fc.mu.Unlock()
+	return mt, nil
+}
+
+func readModifiedTime(path string) (string, bool) {
+	cf, ok := readCacheFile(path)
+	if !ok {
+		return "", false
+	}
+	return cf.ModifiedTime, cf.ModifiedTime != ""
+}
+
+func readCacheFile(path string) (cacheFile, bool) {
+	b, err := os.ReadFile(path)
+	if err != nil {
+		return cacheFile{}, false
+	}
+	var cf cacheFile
+	if err := json.Unmarshal(b, &cf); err != nil {
+		return cacheFile{}, false
+	}
+	return cf, true
+}
+
+func readCache[T any](path, currentModTime string) (T, bool) {
+	cf, ok := readCacheFile(path)
+	if !ok || cf.ModifiedTime != currentModTime {
+		return *new(T), false
+	}
+	var v T
+	if err := json.Unmarshal(cf.Data, &v); err != nil {
+		return *new(T), false
+	}
+	return v, true
+}
+
+func writeCache(path, modTime string, data any) error {
+	raw, err := json.Marshal(data)
+	if err != nil {
+		return err
+	}
+	cf := cacheFile{
+		ModifiedTime: modTime,
+		Data:         json.RawMessage(raw),
+		CachedAt:     time.Now().Format(time.RFC3339),
+	}
+	b, err := json.Marshal(cf)
+	if err != nil {
+		return err
+	}
+	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
+		return err
+	}
+	tmp := path + ".tmp"
+	if err := os.WriteFile(tmp, b, 0o600); err != nil {
+		return err
+	}
+	return os.Rename(tmp, path)
+}
+
+// Ensure *drive.Client satisfies DriveClient at compile time.
+var _ DriveClient = (*drive.Client)(nil)
--- a/go/internal/io/cache/filecache_test.go
+++ b/go/internal/io/cache/filecache_test.go
@@ -0,0 +1,125 @@
+package cache
+
+import (
+	"context"
+	"errors"
+	"fuj-management/go/internal/io/drive"
+	"os"
+	"testing"
+	"time"
+)
+
+func TestGet_FreshFetch(t *testing.T) {
+	dir := t.TempDir()
+	d := &drive.Fake{Times: map[string]string{"sheet1": "2026-01-01T00:00:00Z"}}
+	fc := New(d, dir, map[string]string{"mykey": "sheet1"}, time.Minute, time.Minute)
+
+	calls := 0
+	got, err := Get(context.Background(), fc, "mykey", func(_ context.Context) ([]string, error) {
+		calls++
+		return []string{"a", "b"}, nil
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(got) != 2 || got[0] != "a" {
+		t.Errorf("unexpected: %v", got)
+	}
+	if calls != 1 {
+		t.Errorf("want 1 fetch call, got %d", calls)
+	}
+}
+
+func TestGet_CacheHit(t *testing.T) {
+	dir := t.TempDir()
+	d := &drive.Fake{Times: map[string]string{"sheet1": "2026-01-01T00:00:00Z"}}
+	fc := New(d, dir, map[string]string{"mykey": "sheet1"}, time.Minute, time.Minute)
+
+	fetch := func(_ context.Context) ([]string, error) { return []string{"a"}, nil }
+	if _, err := Get(context.Background(), fc, "mykey", fetch); err != nil {
+		t.Fatal(err)
+	}
+
+	// Second call — modifiedTime unchanged, should hit cache
+	calls := 0
+	got, err := Get(context.Background(), fc, "mykey", func(_ context.Context) ([]string, error) {
+		calls++
+		return []string{"SHOULD_NOT_CALL"}, nil
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got[0] != "a" {
+		t.Errorf("want cache hit with 'a', got %q", got[0])
+	}
+	if calls != 0 {
+		t.Errorf("want 0 fetch calls on hit, got %d", calls)
+	}
+}
+
+func TestGet_CacheMiss_OnModifiedTimeChange(t *testing.T) {
+	dir := t.TempDir()
+	d := &drive.Fake{Times: map[string]string{"sheet1": "2026-01-01T00:00:00Z"}}
+	// No TTL guards so we always hit Drive
+	fc := New(d, dir, map[string]string{"mykey": "sheet1"}, 0, 0)
+
+	fetch := func(_ context.Context) ([]string, error) { return []string{"v1"}, nil }
+	if _, err := Get(context.Background(), fc, "mykey", fetch); err != nil {
+		t.Fatal(err)
+	}
+
+	// Sheet updated — change modifiedTime
+	d.Times["sheet1"] = "2026-02-01T00:00:00Z"
+	got, err := Get(context.Background(), fc, "mykey", func(_ context.Context) ([]string, error) {
+		return []string{"v2"}, nil
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got[0] != "v2" {
+		t.Errorf("want v2 after sheet update, got %q", got[0])
+	}
+}
+
+func TestGet_DriveFailureFallback(t *testing.T) {
+	dir := t.TempDir()
+	d := &drive.Fake{Err: errors.New("drive down")}
+	fc := New(d, dir, nil, 0, 0)
+
+	calls := 0
+	_, err := Get(context.Background(), fc, "mykey", func(_ context.Context) ([]string, error) {
+		calls++
+		return []string{"fallback"}, nil
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if calls != 1 {
+		t.Errorf("want 1 fetch call, got %d", calls)
+	}
+}
+
+func TestFlush(t *testing.T) {
+	dir := t.TempDir()
+	d := &drive.Fake{Times: map[string]string{"sheet1": "t1"}}
+	fc := New(d, dir, map[string]string{"k": "sheet1"}, 0, 0)
+
+	if _, err := Get(context.Background(), fc, "k", func(_ context.Context) (int, error) { return 42, nil }); err != nil {
+		t.Fatal(err)
+	}
+
+	n, err := fc.Flush()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if n != 1 {
+		t.Errorf("want 1 deleted file, got %d", n)
+	}
+	// Cache dir should be empty of _cache.json files
+	entries, _ := os.ReadDir(dir)
+	for _, e := range entries {
+		if e.Name() != "" {
+			t.Errorf("expected empty dir after flush, found %s", e.Name())
+		}
+	}
+}
--- a/go/internal/io/drive/client.go
+++ b/go/internal/io/drive/client.go
@@ -0,0 +1,46 @@
+// Package drive provides a thin wrapper around the Google Drive v3 API,
+// used only to read modifiedTime for cache invalidation.
+package drive
+
+import (
+	"context"
+	"net/http"
+	"time"
+
+	"google.golang.org/api/drive/v3"
+	"google.golang.org/api/option"
+)
+
+// Client wraps the Drive v3 API, scoped to read-only modifiedTime checks.
+type Client struct {
+	svc *drive.Service
+}
+
+// New builds a Client using a service-account credentials file.
+// timeout applies to each Drive API call.
+func New(ctx context.Context, credentialsPath string, timeout time.Duration) (*Client, error) {
+	hc := &http.Client{Timeout: timeout}
+	svc, err := drive.NewService(ctx,
+		option.WithCredentialsFile(credentialsPath), //nolint:staticcheck
+		option.WithScopes(drive.DriveReadonlyScope),
+		option.WithHTTPClient(hc),
+	)
+	if err != nil {
+		return nil, err
+	}
+	return &Client{svc: svc}, nil
+}
+
+// ModifiedTime returns the RFC3339 modifiedTime for the given Drive file ID.
+// Returns ("", err) if the Drive API call fails.
+func (c *Client) ModifiedTime(ctx context.Context, fileID string) (string, error) {
+	meta, err := c.svc.Files.Get(fileID).
+		Fields("modifiedTime").
+		SupportsAllDrives(true).
+		Context(ctx).
+		Do()
+	if err != nil {
+		return "", err
+	}
+	return meta.ModifiedTime, nil
+}
--- a/go/internal/io/drive/fake.go
+++ b/go/internal/io/drive/fake.go
@@ -0,0 +1,18 @@
+package drive
+
+import "context"
+
+// Fake is an in-memory replacement for Client used in tests.
+type Fake struct {
+	// Times maps file ID → modifiedTime string returned by ModifiedTime.
+	Times map[string]string
+	// Err, if non-nil, is returned instead of looking up Times.
+	Err error
+}
+
+func (f *Fake) ModifiedTime(_ context.Context, fileID string) (string, error) {
+	if f.Err != nil {
+		return "", f.Err
+	}
+	return f.Times[fileID], nil
+}
--- a/go/internal/io/fio/api.go
+++ b/go/internal/io/fio/api.go
@@ -0,0 +1,128 @@
+package fio
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"time"
+)
+
+// httpDoer is the subset of *http.Client used by both Fio impls.
+type httpDoer interface {
+	Do(*http.Request) (*http.Response, error)
+}
+
+// apiClient fetches transactions from the Fio REST API (JSON).
+// Ports scripts/fio_utils.py fetch_transactions_api.
+type apiClient struct {
+	token string
+	hc    httpDoer
+}
+
+func (c *apiClient) FetchTransactions(ctx context.Context, from, to time.Time) ([]Transaction, error) {
+	const layout = "2006-01-02"
+	url := fmt.Sprintf("https://fioapi.fio.cz/v1/rest/periods/%s/%s/%s/transactions.json",
+		c.token, from.Format(layout), to.Format(layout))
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return nil, err
+	}
+	resp, err := c.hc.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("fio api: HTTP %d", resp.StatusCode)
+	}
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+	return parseAPIResponse(body)
+}
+
+// fioAPIResponse is the top-level envelope from the Fio JSON API.
+type fioAPIResponse struct {
+	AccountStatement struct {
+		TransactionList struct {
+			Transaction []map[string]json.RawMessage `json:"transaction"`
+		} `json:"transactionList"`
+	} `json:"accountStatement"`
+}
+
+func parseAPIResponse(body []byte) ([]Transaction, error) {
+	var resp fioAPIResponse
+	if err := json.Unmarshal(body, &resp); err != nil {
+		return nil, fmt.Errorf("fio api: parse JSON: %w", err)
+	}
+
+	var txns []Transaction
+	for _, raw := range resp.AccountStatement.TransactionList.Transaction {
+		amount := colFloat(raw, "column1")
+		if amount <= 0 {
+			continue // skip outgoing
+		}
+		dateRaw := colString(raw, "column0")
+		dateStr := ""
+		if len(dateRaw) >= 10 {
+			dateStr = dateRaw[:10]
+		}
+		txns = append(txns, Transaction{
+			Date:          dateStr,
+			Amount:        amount,
+			Sender:        colString(raw, "column10"),
+			Message:       colString(raw, "column16"),
+			VS:            colString(raw, "column5"),
+			KS:            colString(raw, "column4"),
+			SS:            colString(raw, "column6"),
+			UserID:        colString(raw, "column7"),
+			SenderAccount: colString(raw, "column2"),
+			BankID:        colString(raw, "column22"),
+			Currency:      colStringOr(raw, "column14", "CZK"),
+		})
+	}
+	return txns, nil
+}
+
+// colString extracts {"value":…} as a string from a column map.
+func colString(m map[string]json.RawMessage, col string) string {
+	raw, ok := m[col]
+	if !ok {
+		return ""
+	}
+	var cell struct {
+		Value *string `json:"value"`
+	}
+	if json.Unmarshal(raw, &cell) != nil || cell.Value == nil {
+		return ""
+	}
+	return *cell.Value
+}
+
+// colStringOr is colString with a fallback value.
+func colStringOr(m map[string]json.RawMessage, col, fallback string) string {
+	if v := colString(m, col); v != "" {
+		return v
+	}
+	return fallback
+}
+
+// colFloat extracts {"value":…} as a float64 from a column map.
+// Returns 0 on any error (null column, non-numeric value).
+func colFloat(m map[string]json.RawMessage, col string) float64 {
+	raw, ok := m[col]
+	if !ok {
+		return 0
+	}
+	var cell struct {
+		Value *float64 `json:"value"`
+	}
+	if json.Unmarshal(raw, &cell) != nil || cell.Value == nil {
+		return 0
+	}
+	return *cell.Value
+}
--- a/go/internal/io/fio/client.go
+++ b/go/internal/io/fio/client.go
@@ -0,0 +1,37 @@
+// Package fio fetches Fio bank transactions via the JSON API or the
+// transparent-page HTML scraper, behind a common Client interface.
+package fio
+
+import (
+	"context"
+	"time"
+)
+
+// Transaction is one incoming bank payment. Fields absent from the HTML scraper
+// (BankID, Currency, UserID, SenderAccount) are empty strings on that path.
+type Transaction struct {
+	Date          string
+	Amount        float64
+	Sender        string
+	Message       string
+	VS            string
+	KS            string
+	SS            string
+	UserID        string // column7; empty on HTML path
+	SenderAccount string // column2; empty on HTML path
+	BankID        string // column22; empty on HTML path
+	Currency      string // column14; empty on HTML path (assume CZK)
+}
+
+// Client fetches transactions for a date window.
+type Client interface {
+	FetchTransactions(ctx context.Context, from, to time.Time) ([]Transaction, error)
+}
+
+// New returns an apiClient when token is non-empty, otherwise a transparentClient.
+func New(token, accountNum string, hc httpDoer) Client {
+	if token != "" {
+		return &apiClient{token: token, hc: hc}
+	}
+	return &transparentClient{accountNum: accountNum, hc: hc}
+}
--- a/go/internal/io/fio/fake.go
+++ b/go/internal/io/fio/fake.go
@@ -0,0 +1,19 @@
+package fio
+
+import (
+	"context"
+	"time"
+)
+
+// Fake is an in-memory replacement for Client, used in tests.
+type Fake struct {
+	Transactions []Transaction
+	Err          error
+}
+
+func (f *Fake) FetchTransactions(_ context.Context, _, _ time.Time) ([]Transaction, error) {
+	if f.Err != nil {
+		return nil, f.Err
+	}
+	return f.Transactions, nil
+}
--- a/go/internal/io/fio/fio_test.go
+++ b/go/internal/io/fio/fio_test.go
@@ -0,0 +1,157 @@
+package fio
+
+import (
+	"context"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"testing"
+	"time"
+)
+
+func TestAPIClient_ParseResponse(t *testing.T) {
+	body, err := os.ReadFile("testdata/api_response.json")
+	if err != nil {
+		t.Fatal(err)
+	}
+	txns, err := parseAPIResponse(body)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(txns) != 1 {
+		t.Fatalf("want 1 txn (outgoing filtered), got %d", len(txns))
+	}
+	tx := txns[0]
+	if tx.Date != "2026-04-10" {
+		t.Errorf("date: want '2026-04-10', got %q", tx.Date)
+	}
+	if tx.Amount != 750 {
+		t.Errorf("amount: want 750, got %v", tx.Amount)
+	}
+	if tx.Sender != "Jana Novakova" {
+		t.Errorf("sender: want 'Jana Novakova', got %q", tx.Sender)
+	}
+	if tx.Message != "duben 2026" {
+		t.Errorf("message: want 'duben 2026', got %q", tx.Message)
+	}
+	if tx.VS != "123" {
+		t.Errorf("vs: want '123', got %q", tx.VS)
+	}
+	if tx.BankID != "12345678901" {
+		t.Errorf("bank_id: want '12345678901', got %q", tx.BankID)
+	}
+}
+
+func TestAPIClient_HTTPRoundTrip(t *testing.T) {
+	body, _ := os.ReadFile("testdata/api_response.json")
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		_, _ = w.Write(body)
+	}))
+	defer srv.Close()
+
+	c := &apiClient{token: "TESTTOKEN", hc: &overrideClient{base: srv.Client(), baseURL: srv.URL}}
+	txns, err := c.FetchTransactions(context.Background(), time.Now().AddDate(0, -1, 0), time.Now())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(txns) != 1 {
+		t.Fatalf("want 1 txn, got %d", len(txns))
+	}
+}
+
+func TestTransparentClient_ParseHTML(t *testing.T) {
+	body, err := os.ReadFile("testdata/transparent.html")
+	if err != nil {
+		t.Fatal(err)
+	}
+	txns, err := parseTransparentHTML(body)
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Only the incoming row (750 CZK) should be kept; -200 is outgoing
+	if len(txns) != 1 {
+		t.Fatalf("want 1 txn (outgoing filtered), got %d", len(txns))
+	}
+	tx := txns[0]
+	if tx.Date != "2026-04-10" {
+		t.Errorf("date: want '2026-04-10', got %q", tx.Date)
+	}
+	if tx.Amount != 750 {
+		t.Errorf("amount: want 750, got %v", tx.Amount)
+	}
+	if tx.Sender != "Jana Novakova" {
+		t.Errorf("sender: want 'Jana Novakova', got %q", tx.Sender)
+	}
+	if tx.VS != "123" {
+		t.Errorf("vs: want '123', got %q", tx.VS)
+	}
+	if tx.BankID != "" {
+		t.Errorf("bank_id: want empty on HTML path, got %q", tx.BankID)
+	}
+}
+
+func TestParseCzechDate(t *testing.T) {
+	cases := []struct{ in, want string }{
+		{"10.04.2026", "2026-04-10"},
+		{"10/04/2026", "2026-04-10"},
+		{"", ""},
+		{"invalid", ""},
+	}
+	for _, c := range cases {
+		if got := parseCzechDate(c.in); got != c.want {
+			t.Errorf("parseCzechDate(%q) = %q, want %q", c.in, got, c.want)
+		}
+	}
+}
+
+func TestParseCzechAmount(t *testing.T) {
+	cases := []struct {
+		in   string
+		want float64
+	}{
+		{"750,00 CZK", 750},
+		{"1.500,00", 1500},
+		{"1500.00", 1500},
+		{"-200,00 CZK", -200},
+	}
+	for _, c := range cases {
+		if got := parseCzechAmount(c.in); got != c.want {
+			t.Errorf("parseCzechAmount(%q) = %v, want %v", c.in, got, c.want)
+		}
+	}
+}
+
+func TestFake(t *testing.T) {
+	f := &Fake{Transactions: []Transaction{{Date: "2026-04-01", Amount: 500}}}
+	txns, err := f.FetchTransactions(context.Background(), time.Now(), time.Now())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(txns) != 1 || txns[0].Date != "2026-04-01" {
+		t.Errorf("unexpected: %v", txns)
+	}
+}
+
+// overrideClient replaces the URL in requests so we can hit a local test server
+// instead of the real Fio URL.
+type overrideClient struct {
+	base    *http.Client
+	baseURL string
+}
+
+func (o *overrideClient) Do(req *http.Request) (*http.Response, error) {
+	r2, _ := http.NewRequestWithContext(req.Context(), req.Method, o.baseURL+req.URL.Path, nil)
+	resp, err := o.base.Do(r2)
+	if err != nil {
+		return nil, err
+	}
+	// The api client reads the body, so re-serve whatever the test server returned.
+	return resp, nil
+}
+
+// verify Fake satisfies Client
+var _ Client = (*Fake)(nil)
+
+// ensure io.ReadAll isn't called at top level (compile-time reference suppressor)
+var _ = io.ReadAll
--- a/go/internal/io/fio/testdata/api_response.json
+++ b/go/internal/io/fio/testdata/api_response.json
@@ -0,0 +1,29 @@
+{
+  "accountStatement": {
+    "transactionList": {
+      "transaction": [
+        {
+          "column0": {"value": "2026-04-10+0200", "name": "Datum", "id": 0},
+          "column1": {"value": 750.0, "name": "Objem", "id": 1},
+          "column2": {"value": "123456789/0300", "name": "Protiúčet", "id": 2},
+          "column4": {"value": "0308", "name": "KS", "id": 4},
+          "column5": {"value": "123", "name": "VS", "id": 5},
+          "column6": {"value": "", "name": "SS", "id": 6},
+          "column7": {"value": "Jana Nováková", "name": "Uživatelská identifikace", "id": 7},
+          "column10": {"value": "Jana Novakova", "name": "Název protiúčtu", "id": 10},
+          "column14": {"value": "CZK", "name": "Měna", "id": 14},
+          "column16": {"value": "duben 2026", "name": "Zpráva pro příjemce", "id": 16},
+          "column22": {"value": "12345678901", "name": "ID operace", "id": 22}
+        },
+        {
+          "column0": {"value": "2026-04-11+0200", "name": "Datum", "id": 0},
+          "column1": {"value": -200.0, "name": "Objem", "id": 1},
+          "column10": {"value": "Outgoing", "name": "Název protiúčtu", "id": 10},
+          "column14": {"value": "CZK", "name": "Měna", "id": 14},
+          "column16": {"value": "", "name": "Zpráva pro příjemce", "id": 16},
+          "column22": {"value": "99999999999", "name": "ID operace", "id": 22}
+        }
+      ]
+    }
+  }
+}
--- a/go/internal/io/fio/testdata/transparent.html
+++ b/go/internal/io/fio/testdata/transparent.html
@@ -0,0 +1,37 @@
+<!DOCTYPE html>
+<html>
+<body>
+<!-- First table (ignored) -->
+<table class="table"><tr><td>ignored</td></tr></table>
+<!-- Second table (target) -->
+<table class="table">
+  <thead>
+    <tr><th>Datum</th><th>Částka</th><th>Typ</th><th>Název protiúčtu</th><th>Zpráva</th><th>KS</th><th>VS</th><th>SS</th><th>Poznámka</th></tr>
+  </thead>
+  <tbody>
+    <tr>
+      <td>10.04.2026</td>
+      <td>750,00&nbsp;CZK</td>
+      <td>Příjem</td>
+      <td>Jana Novakova</td>
+      <td>duben 2026</td>
+      <td>0308</td>
+      <td>123</td>
+      <td></td>
+      <td></td>
+    </tr>
+    <tr>
+      <td>09.04.2026</td>
+      <td>-200,00&nbsp;CZK</td>
+      <td>Odchozí</td>
+      <td>Someone</td>
+      <td>outgoing</td>
+      <td></td>
+      <td></td>
+      <td></td>
+      <td></td>
+    </tr>
+  </tbody>
+</table>
+</body>
+</html>
--- a/go/internal/io/fio/transparent.go
+++ b/go/internal/io/fio/transparent.go
@@ -0,0 +1,217 @@
+package fio
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"regexp"
+	"strings"
+	"time"
+	"unicode"
+
+	ghtml "golang.org/x/net/html"
+)
+
+// transparentClient fetches transactions from the Fio transparent account page (HTML).
+// Ports scripts/fio_utils.py FioTableParser + fetch_transactions_transparent.
+type transparentClient struct {
+	accountNum string
+	hc         httpDoer
+}
+
+func (c *transparentClient) FetchTransactions(ctx context.Context, from, to time.Time) ([]Transaction, error) {
+	// Transparent page date format: D.M.YYYY
+	url := fmt.Sprintf(
+		"https://ib.fio.cz/ib/transparent?a=%s&f=%s&t=%s",
+		c.accountNum,
+		from.Format("2.1.2006"),
+		to.Format("2.1.2006"),
+	)
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return nil, err
+	}
+	resp, err := c.hc.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("fio transparent: HTTP %d", resp.StatusCode)
+	}
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+	return parseTransparentHTML(body)
+}
+
+// Column indices in the transparent-page table (0-based).
+// Datum | Částka | Typ | Název protiúčtu | Zpráva pro příjemce | KS | VS | SS | Poznámka
+const (
+	tColDate    = 0
+	tColAmount  = 1
+	tColSender  = 3
+	tColMessage = 4
+	tColKS      = 5
+	tColVS      = 6
+	tColSS      = 7
+)
+
+func parseTransparentHTML(body []byte) ([]Transaction, error) {
+	rows := extractSecondTableRows(body)
+
+	var txns []Transaction
+	for _, row := range rows {
+		col := func(i int) string {
+			if i < len(row) {
+				return strings.TrimSpace(row[i])
+			}
+			return ""
+		}
+		dateStr := parseCzechDate(col(tColDate))
+		amount := parseCzechAmount(col(tColAmount))
+		if dateStr == "" || amount <= 0 {
+			continue
+		}
+		txns = append(txns, Transaction{
+			Date:    dateStr,
+			Amount:  amount,
+			Sender:  col(tColSender),
+			Message: col(tColMessage),
+			KS:      col(tColKS),
+			VS:      col(tColVS),
+			SS:      col(tColSS),
+			BankID:  "", // not available on HTML path
+		})
+	}
+	return txns, nil
+}
+
+// extractSecondTableRows walks the HTML token stream and returns data rows
+// from the second <table class="table"> element, skipping the <thead>.
+func extractSecondTableRows(body []byte) [][]string {
+	z := ghtml.NewTokenizer(strings.NewReader(string(body)))
+
+	tableCount := 0
+	inTarget := false
+	inThead := false
+	inRow := false
+	inCell := false
+	var currentRow []string
+	var cellBuf strings.Builder
+	var rows [][]string
+
+	for {
+		tt := z.Next()
+		if tt == ghtml.ErrorToken {
+			break
+		}
+		switch tt {
+		case ghtml.StartTagToken:
+			t := z.Token()
+			switch t.Data {
+			case "table":
+				if hasClass(t, "table") {
+					tableCount++
+					if tableCount == 2 {
+						inTarget = true
+					}
+				}
+			case "thead":
+				if inTarget {
+					inThead = true
+				}
+			case "tr":
+				if inTarget && !inThead {
+					inRow = true
+					currentRow = nil
+				}
+			case "td", "th":
+				if inRow {
+					inCell = true
+					cellBuf.Reset()
+				}
+			}
+		case ghtml.EndTagToken:
+			t := z.Token()
+			switch t.Data {
+			case "td", "th":
+				if inCell {
+					currentRow = append(currentRow, cellBuf.String())
+					inCell = false
+				}
+			case "thead":
+				inThead = false
+			case "tr":
+				if inRow {
+					if len(currentRow) > 0 {
+						rows = append(rows, currentRow)
+					}
+					inRow = false
+				}
+			case "table":
+				if inTarget {
+					return rows
+				}
+			}
+		case ghtml.TextToken:
+			if inCell {
+				cellBuf.WriteString(z.Token().Data)
+			}
+		}
+	}
+	return rows
+}
+
+func hasClass(t ghtml.Token, cls string) bool {
+	for _, a := range t.Attr {
+		if a.Key == "class" {
+			for _, c := range strings.Fields(a.Val) {
+				if c == cls {
+					return true
+				}
+			}
+		}
+	}
+	return false
+}
+
+// parseCzechDate parses "DD.MM.YYYY" or "DD/MM/YYYY" → "YYYY-MM-DD".
+// Returns "" on parse error.
+func parseCzechDate(s string) string {
+	s = strings.TrimSpace(s)
+	for _, layout := range []string{"02.01.2006", "02/01/2006"} {
+		if t, err := time.Parse(layout, s); err == nil {
+			return t.Format("2006-01-02")
+		}
+	}
+	return ""
+}
+
+var nonNumericRe = regexp.MustCompile(`[^\d.,]`)
+
+// parseCzechAmount parses "1 500,00 CZK" / "1.500,00" / "1500.00" → float64.
+// Returns 0 on error.
+func parseCzechAmount(s string) float64 {
+	// Remove NBSP, regular spaces, currency letters
+	s = strings.Map(func(r rune) rune {
+		if r == ' ' || unicode.IsSpace(r) || unicode.IsLetter(r) {
+			return -1
+		}
+		return r
+	}, s)
+
+	if strings.Contains(s, ",") {
+		// Czech decimal: 1.500,00 → remove dots (thousand sep), comma → dot
+		s = strings.ReplaceAll(s, ".", "")
+		s = strings.ReplaceAll(s, ",", ".")
+	} else {
+		// Remove any remaining non-numeric except one dot
+		s = nonNumericRe.ReplaceAllString(s, "")
+	}
+	var f float64
+	_, _ = fmt.Sscanf(s, "%f", &f)
+	return f
+}
--- a/go/internal/io/sheets/client.go
+++ b/go/internal/io/sheets/client.go
@@ -0,0 +1,124 @@
+// Package sheets provides a typed wrapper around the Google Sheets v4 API.
+package sheets
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"google.golang.org/api/option"
+	sheetsv4 "google.golang.org/api/sheets/v4"
+)
+
+// ValueRange pairs an R1C1 range with its cell values, used for batchUpdate.
+type ValueRange struct {
+	Range  string  // R1C1 notation, e.g. "R2C4:R2C6"
+	Values [][]any // one sub-slice per row
+}
+
+// Client wraps the Sheets v4 API with the operations needed by this project.
+type Client struct {
+	svc *sheetsv4.Service
+}
+
+// New builds a Client using a service-account credentials file.
+func New(ctx context.Context, credentialsPath string, _ time.Duration) (*Client, error) {
+	svc, err := sheetsv4.NewService(ctx,
+		option.WithCredentialsFile(credentialsPath), //nolint:staticcheck
+		option.WithScopes(sheetsv4.SpreadsheetsScope),
+	)
+	if err != nil {
+		return nil, err
+	}
+	return &Client{svc: svc}, nil
+}
+
+// GetValues fetches a range from a spreadsheet with UNFORMATTED_VALUE rendering
+// (numbers as numbers, dates as serial floats — matching Python's behaviour).
+func (c *Client) GetValues(ctx context.Context, spreadsheetID, a1Range string) ([][]any, error) {
+	resp, err := c.svc.Spreadsheets.Values.
+		Get(spreadsheetID, a1Range).
+		ValueRenderOption("UNFORMATTED_VALUE").
+		Context(ctx).
+		Do()
+	if err != nil {
+		return nil, err
+	}
+	rows := make([][]any, len(resp.Values))
+	copy(rows, resp.Values)
+	return rows, nil
+}
+
+// AppendValues appends rows to the first empty row after a1Range.
+func (c *Client) AppendValues(ctx context.Context, spreadsheetID, a1Range string, rows [][]any) error {
+	vals := make([][]any, len(rows))
+	copy(vals, rows)
+	_, err := c.svc.Spreadsheets.Values.
+		Append(spreadsheetID, a1Range, &sheetsv4.ValueRange{Values: vals}).
+		ValueInputOption("USER_ENTERED").
+		Context(ctx).
+		Do()
+	return err
+}
+
+// BatchUpdateValues writes multiple non-contiguous ranges in one API call.
+func (c *Client) BatchUpdateValues(ctx context.Context, spreadsheetID string, updates []ValueRange) error {
+	data := make([]*sheetsv4.ValueRange, len(updates))
+	for i, u := range updates {
+		vals := make([][]any, len(u.Values))
+		copy(vals, u.Values)
+		data[i] = &sheetsv4.ValueRange{Range: u.Range, Values: vals}
+	}
+	_, err := c.svc.Spreadsheets.Values.
+		BatchUpdate(spreadsheetID, &sheetsv4.BatchUpdateValuesRequest{
+			ValueInputOption: "USER_ENTERED",
+			Data:             data,
+		}).
+		Context(ctx).
+		Do()
+	return err
+}
+
+// WriteHeader overwrites row 1 of the spreadsheet with the given labels.
+func (c *Client) WriteHeader(ctx context.Context, spreadsheetID string, labels []string) error {
+	row := make([]any, len(labels))
+	for i, l := range labels {
+		row[i] = l
+	}
+	_, err := c.svc.Spreadsheets.Values.
+		Update(spreadsheetID, "A1", &sheetsv4.ValueRange{Values: [][]any{row}}).
+		ValueInputOption("USER_ENTERED").
+		Context(ctx).
+		Do()
+	return err
+}
+
+// SortByDateColumn sorts rows 2..10000 of the first sheet ascending by column A (Date).
+// Looks up the sheetId (gid) from spreadsheet metadata.
+func (c *Client) SortByDateColumn(ctx context.Context, spreadsheetID string) error {
+	meta, err := c.svc.Spreadsheets.Get(spreadsheetID).Context(ctx).Do()
+	if err != nil {
+		return fmt.Errorf("sheets: get spreadsheet: %w", err)
+	}
+	if len(meta.Sheets) == 0 {
+		return fmt.Errorf("sheets: spreadsheet has no sheets")
+	}
+	sheetID := meta.Sheets[0].Properties.SheetId
+
+	_, err = c.svc.Spreadsheets.BatchUpdate(spreadsheetID, &sheetsv4.BatchUpdateSpreadsheetRequest{
+		Requests: []*sheetsv4.Request{{
+			SortRange: &sheetsv4.SortRangeRequest{
+				Range: &sheetsv4.GridRange{
+					SheetId:       sheetID,
+					StartRowIndex: 1,
+					EndRowIndex:   10000,
+				},
+				SortSpecs: []*sheetsv4.SortSpec{{
+					DimensionIndex: 0,
+					SortOrder:      "ASCENDING",
+				}},
+			},
+		}},
+	}).Context(ctx).Do()
+	return err
+}
--- a/go/internal/io/sheets/fake.go
+++ b/go/internal/io/sheets/fake.go
@@ -0,0 +1,53 @@
+package sheets
+
+import (
+	"context"
+	"fmt"
+)
+
+// Fake is an in-memory replacement for Client used in tests.
+// Values maps a "<spreadsheetID>/<a1Range>" key to pre-seeded rows.
+type Fake struct {
+	// Values maps "spreadsheetID/range" → rows returned by GetValues.
+	Values map[string][][]any
+	// Appended collects rows passed to AppendValues for assertion.
+	Appended []AppendCall
+	// BatchUpdated collects calls to BatchUpdateValues.
+	BatchUpdated []BatchCall
+}
+
+// AppendCall records one AppendValues invocation.
+type AppendCall struct {
+	SpreadsheetID string
+	Range         string
+	Rows          [][]any
+}
+
+// BatchCall records one BatchUpdateValues invocation.
+type BatchCall struct {
+	SpreadsheetID string
+	Updates       []ValueRange
+}
+
+func (f *Fake) GetValues(_ context.Context, spreadsheetID, a1Range string) ([][]any, error) {
+	key := spreadsheetID + "/" + a1Range
+	rows, ok := f.Values[key]
+	if !ok {
+		return nil, fmt.Errorf("sheets fake: no seed for %q", key)
+	}
+	return rows, nil
+}
+
+func (f *Fake) AppendValues(_ context.Context, spreadsheetID, a1Range string, rows [][]any) error {
+	f.Appended = append(f.Appended, AppendCall{SpreadsheetID: spreadsheetID, Range: a1Range, Rows: rows})
+	return nil
+}
+
+func (f *Fake) BatchUpdateValues(_ context.Context, spreadsheetID string, updates []ValueRange) error {
+	f.BatchUpdated = append(f.BatchUpdated, BatchCall{SpreadsheetID: spreadsheetID, Updates: updates})
+	return nil
+}
+
+func (f *Fake) WriteHeader(_ context.Context, _ string, _ []string) error { return nil }
+
+func (f *Fake) SortByDateColumn(_ context.Context, _ string) error { return nil }