Feature 19: Notifications - Web Push and Google Chat (#169)

Co-authored-by: orchestrator-agent <20+orchestrator-agent@code.cubecraftcreations.com>

internal/chat/chat.go

@@ -0,0 +1,519 @@
+// Package chat sends notifications to the household's Google Chat space
+// through its incoming webhook, and keeps that webhook in chat_settings.
+//
+// The webhook URL carries its own key and token, so it is a secret: it is
+// sealed with secretbox in webhook_url_ct and is never returned, logged or
+// put in an error. Only its space label, a masked tail and the outcome of
+// the last test message are shown.
+package chat
+
+import (
+	"bytes"
+	"context"
+	"database/sql"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strings"
+	"time"
+	"unicode/utf8"
+
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/db"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/household"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/jobs"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/notify"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/secretbox"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/store"
+)
+
+const (
+	// MaxSpaceLabelChars bounds a space label.
+	MaxSpaceLabelChars = 100
+	// requestTimeout bounds one post to Google Chat.
+	requestTimeout = 15 * time.Second
+	// maxDrainBytes bounds how much of a Google Chat response is read.
+	maxDrainBytes = 4096
+	// replyOption threads a message under its threadKey, starting the
+	// thread when there is none yet.
+	replyOption = "REPLY_MESSAGE_FALLBACK_TO_NEW_THREAD"
+)
+
+// Test outcomes, as chat_settings.last_test_status stores them.
+const (
+	TestOK     = "ok"
+	TestFailed = "failed"
+)
+
+var (
+	// ErrNotConfigured is returned when no webhook is stored.
+	ErrNotConfigured = errors.New("chat: no Google Chat webhook is configured")
+	// ErrUnreachable is wrapped by the error of a post Google Chat did not
+	// answer.
+	ErrUnreachable = errors.New("chat: Google Chat did not answer")
+	// ErrRefused is matched by the *RefusedError of a post Google Chat
+	// answered with a status other than 2xx.
+	ErrRefused = errors.New("chat: Google Chat refused the message")
+	// ErrWebhookChanged is returned by Test when the webhook was replaced
+	// while the test message was being sent; nothing is recorded.
+	ErrWebhookChanged = errors.New("chat: the Google Chat webhook changed during the test")
+)
+
+// Settings is the stored webhook as the API shows it: never the URL, only
+// its masked form. URLMasked is nil when no webhook is stored.
+type Settings struct {
+	SpaceLabel *string `json:"space_label"`
+	// URLMasked is the webhook URL without its key and with only the last
+	// few characters of its token.
+	URLMasked *string `json:"url_masked"`
+	// LastTestAt and LastTestStatus ("ok" or "failed") are nil until a
+	// test message is sent to this webhook.
+	LastTestAt     *string `json:"last_test_at"`
+	LastTestStatus *string `json:"last_test_status"`
+}
+
+// TestResult is the outcome of a test message.
+type TestResult struct {
+	// HTTPStatus is the status Google Chat answered.
+	HTTPStatus int `json:"http_status"`
+	Settings
+}
+
+// RefusedError is a post Google Chat answered with Status, not 2xx. It
+// matches ErrRefused.
+type RefusedError struct {
+	Status int
+}
+
+func (e *RefusedError) Error() string {
+	return fmt.Sprintf("%v with status %d", ErrRefused, e.Status)
+}
+
+func (e *RefusedError) Unwrap() error { return ErrRefused }
+
+// Retryable reports whether posting again may succeed: Google Chat was
+// busy (429) or failing (5xx), rather than refusing the message.
+func (e *RefusedError) Retryable() bool {
+	return e.Status == http.StatusTooManyRequests || e.Status >= 500
+}
+
+// Problem is one invalid field of a webhook update, named by its JSON key.
+type Problem struct {
+	Field  string
+	Reason string
+}
+
+// ValidationError lists every problem with a webhook update. It never
+// quotes the URL.
+type ValidationError struct {
+	Problems []Problem
+}
+
+func (e *ValidationError) Error() string {
+	parts := make([]string, len(e.Problems))
+	for i, p := range e.Problems {
+		parts[i] = p.Field + ": " + p.Reason
+	}
+	return "invalid Google Chat webhook: " + strings.Join(parts, "; ")
+}
+
+// Service keeps the webhook and posts to it. It is the notify.Sender of the
+// chat channel.
+type Service struct {
+	st  *store.Store
+	box *secretbox.Box
+	// publicURL is MEALQUEST_PUBLIC_URL, which a card's "Open" button
+	// links under.
+	publicURL *url.URL
+	client    *http.Client
+	// now is the clock settings are saved and tests recorded on; tests
+	// replace it.
+	now func() time.Time
+}
+
+// NewService returns the service over st, sealing the webhook with box and
+// linking cards under publicURL. Requests go through transport
+// (http.DefaultTransport in production) and never follow a redirect.
+func NewService(st *store.Store, box *secretbox.Box, publicURL *url.URL, transport http.RoundTripper) (*Service, error) {
+	switch {
+	case st == nil:
+		return nil, errors.New("chat: nil store")
+	case box == nil:
+		return nil, errors.New("chat: nil secret box")
+	case publicURL == nil:
+		return nil, errors.New("chat: nil public URL")
+	case transport == nil:
+		return nil, errors.New("chat: nil transport")
+	}
+	return &Service{
+		st:        st,
+		box:       box,
+		publicURL: publicURL,
+		client: &http.Client{
+			Transport: transport,
+			Timeout:   requestTimeout,
+			CheckRedirect: func(*http.Request, []*http.Request) error {
+				return http.ErrUseLastResponse
+			},
+		},
+		now: time.Now,
+	}, nil
+}
+
+// Get returns the stored webhook's settings; every field is nil before one
+// is saved.
+func (s *Service) Get(ctx context.Context) (Settings, error) {
+	row, err := db.New(s.st.Reader).GetChatSettings(ctx)
+	if errors.Is(err, sql.ErrNoRows) {
+		return Settings{}, nil
+	}
+	if err != nil {
+		return Settings{}, fmt.Errorf("chat: read chat settings: %w", err)
+	}
+	hook, err := s.open(row)
+	if err != nil {
+		return Settings{}, err
+	}
+	return settingsFrom(row, hook), nil
+}
+
+// Put validates rawURL and spaceLabel and stores them, replacing any
+// webhook stored before and clearing its test outcome. Every problem is
+// reported in a *ValidationError.
+func (s *Service) Put(ctx context.Context, rawURL, spaceLabel string) (Settings, error) {
+	var problems []Problem
+	hook, err := ParseWebhook(rawURL)
+	if err != nil {
+		problems = append(problems, Problem{"url", err.Error()})
+	}
+	label := strings.TrimSpace(spaceLabel)
+	switch {
+	case label == "":
+		problems = append(problems, Problem{"space_label", "is required"})
+	case utf8.RuneCountInString(label) > MaxSpaceLabelChars:
+		problems = append(problems, Problem{"space_label", fmt.Sprintf("must be at most %d characters", MaxSpaceLabelChars)})
+	case strings.ContainsFunc(label, func(r rune) bool { return r < ' ' || r == 0x7f }):
+		problems = append(problems, Problem{"space_label", "must not contain control characters"})
+	}
+	if len(problems) > 0 {
+		return Settings{}, &ValidationError{Problems: problems}
+	}
+	ct, err := s.box.Encrypt([]byte(hook.String()))
+	if err != nil {
+		return Settings{}, fmt.Errorf("chat: seal webhook: %w", err)
+	}
+
+	var saved db.ChatSetting
+	err = s.st.WithTx(ctx, func(tx *sql.Tx) error {
+		q := db.New(tx)
+		row, err := q.GetChatSettings(ctx)
+		if err != nil && !errors.Is(err, sql.ErrNoRows) {
+			return fmt.Errorf("chat: read chat settings: %w", err)
+		}
+		now := s.timestamp()
+		created := now
+		if err == nil {
+			created = row.CreatedAt
+		}
+		saved, err = q.UpsertChatSettings(ctx, db.UpsertChatSettingsParams{
+			WebhookUrlCt: ct,
+			SpaceLabel:   sql.NullString{String: label, Valid: true},
+			CreatedAt:    created,
+			UpdatedAt:    now,
+		})
+		if err != nil {
+			return fmt.Errorf("chat: save chat settings: %w", err)
+		}
+		return nil
+	})
+	if err != nil {
+		return Settings{}, err
+	}
+	return settingsFrom(saved, hook), nil
+}
+
+// Test posts TestText to the stored webhook, unthreaded, and records when
+// and whether Google Chat accepted it. A status Google Chat answers is a
+// TestResult, whatever it is; a request that gets no answer is recorded as
+// failed and returned as an error. A test cut short by ctx records nothing.
+func (s *Service) Test(ctx context.Context) (TestResult, error) {
+	row, err := db.New(s.st.Reader).GetChatSettings(ctx)
+	if errors.Is(err, sql.ErrNoRows) {
+		return TestResult{}, ErrNotConfigured
+	}
+	if err != nil {
+		return TestResult{}, fmt.Errorf("chat: read chat settings: %w", err)
+	}
+	hook, err := s.open(row)
+	if err != nil {
+		return TestResult{}, err
+	}
+	status, postErr := s.post(ctx, hook, message{Text: TestText}, "")
+	if err := ctx.Err(); err != nil {
+		return TestResult{}, err
+	}
+	outcome := TestFailed
+	if postErr == nil && status >= 200 && status < 300 {
+		outcome = TestOK
+	}
+	at := s.timestamp()
+	write, cancel := jobs.FinalWriteContext(ctx)
+	defer cancel()
+	n, err := db.New(s.st.Writer).RecordChatTest(write, db.RecordChatTestParams{
+		LastTestAt:     sql.NullString{String: at, Valid: true},
+		LastTestStatus: sql.NullString{String: outcome, Valid: true},
+		UpdatedAt:      at,
+		WebhookUrlCt:   row.WebhookUrlCt,
+	})
+	if err != nil {
+		return TestResult{}, fmt.Errorf("chat: record test: %w", err)
+	}
+	if n != 1 {
+		return TestResult{}, ErrWebhookChanged
+	}
+	if postErr != nil {
+		return TestResult{}, postErr
+	}
+	row.LastTestAt = sql.NullString{String: at, Valid: true}
+	row.LastTestStatus = sql.NullString{String: outcome, Valid: true}
+	row.UpdatedAt = at
+	return TestResult{HTTPStatus: status, Settings: settingsFrom(row, hook)}, nil
+}
+
+// Send posts m to the stored webhook, threaded by the week of its payload,
+// and is the chat channel's notify.Sender. Google Chat answering 2xx is
+// success; 429 or 5xx, or no answer at all, is an error the outbox
+// retries; any other status, or no webhook stored, wraps
+// notify.ErrUndeliverable so the row fails at once.
+func (s *Service) Send(ctx context.Context, m notify.Message) error {
+	row, err := db.New(s.st.Reader).GetChatSettings(ctx)
+	if errors.Is(err, sql.ErrNoRows) {
+		return fmt.Errorf("%w: %w", notify.ErrUndeliverable, ErrNotConfigured)
+	}
+	if err != nil {
+		return fmt.Errorf("chat: read chat settings: %w", err)
+	}
+	hook, err := s.open(row)
+	if err != nil {
+		return err
+	}
+	msg, err := s.messageOf(m.Payload)
+	if err != nil {
+		return fmt.Errorf("%w: chat: %w", notify.ErrUndeliverable, err)
+	}
+	var thread string
+	if m.Payload.Week != "" {
+		week, err := store.ParseLocalDate(m.Payload.Week)
+		if err != nil {
+			return fmt.Errorf("%w: chat: payload week: %w", notify.ErrUndeliverable, err)
+		}
+		thread = ThreadKey(week)
+	}
+	status, err := s.post(ctx, hook, msg, thread)
+	switch {
+	case err != nil:
+		return err
+	case status >= 200 && status < 300:
+		return nil
+	case status == http.StatusTooManyRequests || status >= 500:
+		return fmt.Errorf("chat: Google Chat answered status %d", status)
+	default:
+		return fmt.Errorf("%w: chat: Google Chat refused the message with status %d", notify.ErrUndeliverable, status)
+	}
+}
+
+// ThreadKey is the Chat thread of the week starting on week, such as
+// "mealquest-week-2026-W42": every message about a week goes in one thread.
+func ThreadKey(week store.LocalDate) string {
+	return "mealquest-week-" + household.PeriodKey(week)
+}
+
+// message is the body of a Google Chat webhook post.
+type message struct {
+	Text    string   `json:"text"`
+	CardsV2 []cardV2 `json:"cardsV2,omitempty"`
+}
+
+type cardV2 struct {
+	CardID string `json:"cardId"`
+	Card   card   `json:"card"`
+}
+
+type card struct {
+	Header   cardHeader    `json:"header"`
+	Sections []cardSection `json:"sections"`
+}
+
+type cardHeader struct {
+	Title    string `json:"title"`
+	Subtitle string `json:"subtitle,omitempty"`
+}
+
+type cardSection struct {
+	Widgets []cardWidget `json:"widgets"`
+}
+
+type cardWidget struct {
+	ButtonList buttonList `json:"buttonList"`
+}
+
+type buttonList struct {
+	Buttons []button `json:"buttons"`
+}
+
+type button struct {
+	Text    string  `json:"text"`
+	OnClick onClick `json:"onClick"`
+}
+
+type onClick struct {
+	OpenLink openLink `json:"openLink"`
+}
+
+type openLink struct {
+	URL string `json:"url"`
+}
+
+// messageOf is the Chat message of p: its Text and, for a plan or Supply
+// run, a card whose "Open" button links to p.URL under the public URL.
+func (s *Service) messageOf(p notify.Payload) (message, error) {
+	msg := message{Text: Text(p)}
+	if !carded[p.Event] {
+		return msg, nil
+	}
+	c, err := s.openCard(string(p.Event), p.Title, p.Body, p.URL)
+	if err != nil {
+		return message{}, err
+	}
+	msg.CardsV2 = []cardV2{c}
+	return msg, nil
+}
+
+// openCard is a card headed title and subtitle whose "Open" button links
+// to the app path under the public URL.
+func (s *Service) openCard(id, title, subtitle, path string) (cardV2, error) {
+	ref, err := url.Parse(path)
+	if err != nil || ref.Scheme != "" || ref.Host != "" || !strings.HasPrefix(path, "/") {
+		return cardV2{}, fmt.Errorf("payload url %q is not an app path", path)
+	}
+	link := s.publicURL.ResolveReference(ref)
+	return cardV2{
+		CardID: id,
+		Card: card{
+			Header: cardHeader{Title: title, Subtitle: subtitle},
+			Sections: []cardSection{{Widgets: []cardWidget{{ButtonList: buttonList{Buttons: []button{{
+				Text:    "Open",
+				OnClick: onClick{OpenLink: openLink{URL: link.String()}},
+			}}}}}}},
+		},
+	}, nil
+}
+
+// PostSupplyRun posts the Supply run of the week starting on week, named
+// name, with groups, to the stored webhook in the week's thread: its
+// SupplyRunText and a card whose "Open" button links to that week's Supply
+// run. No webhook stored is ErrNotConfigured; a post Google Chat does not
+// answer wraps ErrUnreachable, and one it answers with a status other than
+// 2xx is a *RefusedError.
+func (s *Service) PostSupplyRun(ctx context.Context, week store.LocalDate, name string, groups []SupplyRunGroup) error {
+	row, err := db.New(s.st.Reader).GetChatSettings(ctx)
+	if errors.Is(err, sql.ErrNoRows) {
+		return ErrNotConfigured
+	}
+	if err != nil {
+		return fmt.Errorf("chat: read chat settings: %w", err)
+	}
+	hook, err := s.open(row)
+	if err != nil {
+		return err
+	}
+	path := "/plan/shopping?" + url.Values{"week": {week.String()}}.Encode()
+	c, err := s.openCard("supply_run", "Supply run · "+name, "", path)
+	if err != nil {
+		return err
+	}
+	status, err := s.post(ctx, hook, message{Text: SupplyRunText(name, groups), CardsV2: []cardV2{c}}, ThreadKey(week))
+	if err != nil {
+		return err
+	}
+	if status < 200 || status >= 300 {
+		return &RefusedError{Status: status}
+	}
+	return nil
+}
+
+// post sends msg to hook, in thread when it is not empty, and returns the
+// status Google Chat answered. Its error never quotes the webhook URL.
+func (s *Service) post(ctx context.Context, hook Webhook, msg message, thread string) (int, error) {
+	body, err := json.Marshal(msg)
+	if err != nil {
+		return 0, fmt.Errorf("chat: encode message: %w", err)
+	}
+	target, err := url.Parse(hook.String())
+	if err != nil {
+		return 0, errors.New("chat: stored webhook URL does not parse")
+	}
+	if thread != "" {
+		q := target.Query()
+		q.Set("threadKey", thread)
+		q.Set("messageReplyOption", replyOption)
+		target.RawQuery = q.Encode()
+	}
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, target.String(), bytes.NewReader(body))
+	if err != nil {
+		return 0, errors.New("chat: build request to the webhook")
+	}
+	req.Header.Set("Content-Type", "application/json; charset=UTF-8")
+	resp, err := s.client.Do(req)
+	if err != nil {
+		// A *url.Error quotes the request URL, the webhook; keep only its
+		// cause.
+		var ue *url.Error
+		if errors.As(err, &ue) {
+			return 0, fmt.Errorf("%w: %w", ErrUnreachable, ue.Err)
+		}
+		return 0, ErrUnreachable
+	}
+	defer resp.Body.Close()
+	// The status is the outcome; the body is read only so the connection
+	// can be reused.
+	io.CopyN(io.Discard, resp.Body, maxDrainBytes)
+	return resp.StatusCode, nil
+}
+
+// open decrypts and validates the stored webhook. Its error never quotes
+// the URL.
+func (s *Service) open(row db.ChatSetting) (Webhook, error) {
+	raw, err := s.box.Decrypt(row.WebhookUrlCt)
+	if err != nil {
+		return Webhook{}, fmt.Errorf("chat: open stored webhook: %w", err)
+	}
+	hook, err := ParseWebhook(string(raw))
+	if err != nil {
+		return Webhook{}, fmt.Errorf("chat: stored webhook URL is invalid: %w", err)
+	}
+	return hook, nil
+}
+
+func (s *Service) timestamp() string {
+	return store.Timestamp{Time: s.now().UTC().Truncate(time.Millisecond)}.String()
+}
+
+func settingsFrom(row db.ChatSetting, hook Webhook) Settings {
+	masked := hook.Masked()
+	return Settings{
+		SpaceLabel:     nullString(row.SpaceLabel),
+		URLMasked:      &masked,
+		LastTestAt:     nullString(row.LastTestAt),
+		LastTestStatus: nullString(row.LastTestStatus),
+	}
+}
+
+func nullString(s sql.NullString) *string {
+	if !s.Valid {
+		return nil
+	}
+	return &s.String
+}