Implement TweetPersister daemon

daemon/daemon.go

@@ -0,0 +1,30 @@
+package daemon
+
+import (
+	"context"
+	"time"
+
+	"git.netflux.io/rob/elon-eats-my-tweets/twitterapi"
+	"go.uber.org/zap"
+)
+
+// Run blocks until the provided context is terminated.
+func Run(ctx context.Context, store twitterapi.Store, apiClient twitterapi.APIClient, logger *zap.SugaredLogger) error {
+	tweetPersister := TweetPersister{store: store, apiClient: apiClient, logger: logger}
+	ticker := time.NewTicker(time.Second * 10)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ticker.C:
+			if n, err := tweetPersister.PersistTweets(ctx); err != nil {
+				logger.With("err", err, "inserted", n).Error("error updating tweets")
+			} else {
+				logger.With("inserted", n).Info("tweets updated")
+			}
+		case <-ctx.Done():
+			logger.With("err", ctx.Err()).Info("context complete, exiting")
+			return nil
+		}
+	}
+}

daemon/tweet_persister.go

@@ -0,0 +1,105 @@
+package daemon
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"strconv"
+	"time"
+
+	"git.netflux.io/rob/elon-eats-my-tweets/generated/store"
+	"git.netflux.io/rob/elon-eats-my-tweets/twitterapi"
+	"github.com/jackc/pgx/v4"
+	"go.uber.org/zap"
+)
+
+const formatDecimal = 10
+const elonID = "44196397"
+
+// TweetPersister fetches tweets from twitter and persists them in the database.
+type TweetPersister struct {
+	store     twitterapi.Store
+	apiClient twitterapi.APIClient
+	logger    *zap.SugaredLogger
+}
+
+// NewTweetPersister creates a new NewTweetPersister.
+func NewTweetPersister(store twitterapi.Store, apiClient twitterapi.APIClient, logger *zap.SugaredLogger) *TweetPersister {
+	return &TweetPersister{store: store, apiClient: apiClient, logger: logger}
+}
+
+// PersistTweets fetches tweets from Twitter and persists them in the database.
+// In the case there are no tweets in the database, the single most recent
+// tweet will be fetched. Otherwise, the maximum tweets returnable by the
+// Twitter API will be fetched starting from the most recent known tweet. If
+// there are more tweets available, multiple calls to this method will be
+// required to fetch them all.
+func (tu *TweetPersister) PersistTweets(ctx context.Context) (int, error) {
+	lastKnownTweet, err := tu.store.GetLastElonTweet(ctx)
+	if err != nil && err != pgx.ErrNoRows {
+		return 0, fmt.Errorf("error fetching last Elon tweet: %v", err)
+	}
+
+	// we have no Elon tweets at all, this is the first run. Grab the most recent
+	// tweet, and mark it as processed.
+	if err == pgx.ErrNoRows {
+		return tu.insertInitialTweet(ctx)
+	}
+
+	sinceID := strconv.FormatInt(lastKnownTweet.TwitterID, formatDecimal)
+	var n int
+	newTweets, err := tu.apiClient.GetTweets(elonID, sinceID)
+	if err != nil {
+		return n, fmt.Errorf("error fetching latest Elon tweets: %v", err)
+	}
+
+	for _, tweet := range newTweets {
+		if _, storeErr := tu.insertTweet(ctx, tweet, false); storeErr != nil {
+			return n, fmt.Errorf("error inserting tweet: %v", storeErr)
+		}
+
+		n++
+	}
+
+	return n, nil
+}
+
+func (tu *TweetPersister) insertInitialTweet(ctx context.Context) (int, error) {
+	tweet, err := tu.apiClient.GetLastTweet(elonID)
+	if err == twitterapi.ErrNoTweets {
+		tu.logger.Warn("Twitter API returned empty success response, no tweets available.")
+		return 0, nil
+	} else if err != nil {
+		return 0, fmt.Errorf("error fetching initial tweet: %v", err)
+	}
+	if _, err = tu.insertTweet(ctx, tweet, true); err != nil {
+		return 0, fmt.Errorf("error inserting initial tweet: %v", err)
+	}
+
+	return 1, nil
+}
+
+func (tu *TweetPersister) insertTweet(ctx context.Context, tweet *twitterapi.Tweet, markAsProcessed bool) (*store.ElonTweet, error) {
+	twitterID, err := strconv.ParseInt(tweet.ID, 10, 64)
+	if err != nil {
+		return nil, fmt.Errorf("error parsing twitter ID: %v", err)
+	}
+
+	params := store.UpsertElonTweetParams{
+		TwitterID: twitterID,
+		Text:      tweet.Text,
+		PostedAt:  tweet.CreatedAt,
+	}
+	if markAsProcessed {
+		params.ProcessedAt = sql.NullTime{Time: time.Now().UTC(), Valid: true}
+	}
+
+	storeTweet, err := tu.store.UpsertElonTweet(ctx, params)
+	if err != nil {
+		return nil, fmt.Errorf("error upserting tweet: %v", err)
+	}
+
+	tu.logger.With("twitter_id", twitterID, "text", tweet.Text).Infof("new tweet inserted")
+
+	return &storeTweet, nil
+}

daemon/tweet_persister_test.go

@@ -0,0 +1,176 @@
+package daemon_test
+
+import (
+	"context"
+	"errors"
+	"testing"
+	"time"
+
+	"git.netflux.io/rob/elon-eats-my-tweets/daemon"
+	"git.netflux.io/rob/elon-eats-my-tweets/generated/mocks"
+	"git.netflux.io/rob/elon-eats-my-tweets/generated/store"
+	"git.netflux.io/rob/elon-eats-my-tweets/twitterapi"
+	"github.com/jackc/pgx/v4"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/mock"
+	"go.uber.org/zap"
+)
+
+func TestTweetUpdaterUpdateTweetsInitialTweet(t *testing.T) {
+	utcLoc, _ := time.LoadLocation("UTC")
+	createdAt := time.Date(2022, 1, 1, 12, 12, 23, 0, utcLoc)
+
+	testCases := []struct {
+		name              string
+		lastKnownTweetErr error
+		fetchedTweet      *twitterapi.Tweet
+		fetchedTweetErr   error
+		insertTweetErr    error
+		wantCount         int
+		wantErr           string
+	}{
+		{
+			name:              "error fetching last known tweet",
+			lastKnownTweetErr: errors.New("database error"),
+			wantCount:         0,
+			wantErr:           "error fetching last Elon tweet: database error",
+		},
+		{
+			name:              "no tweet available from the API",
+			lastKnownTweetErr: pgx.ErrNoRows,
+			fetchedTweetErr:   twitterapi.ErrNoTweets,
+			wantCount:         0,
+			wantErr:           "",
+		},
+		{
+			name:              "error fetching tweet from API",
+			lastKnownTweetErr: pgx.ErrNoRows,
+			fetchedTweetErr:   errors.New("API error"),
+			wantCount:         0,
+			wantErr:           "error fetching initial tweet: API error",
+		},
+		{
+			name:              "error inserting tweet",
+			lastKnownTweetErr: pgx.ErrNoRows,
+			fetchedTweet:      &twitterapi.Tweet{ID: "101", Text: "bar", CreatedAt: createdAt},
+			insertTweetErr:    errors.New("boom"),
+			wantCount:         0,
+			wantErr:           "error inserting initial tweet: error upserting tweet: boom",
+		},
+		{
+			name:              "success",
+			lastKnownTweetErr: pgx.ErrNoRows,
+			fetchedTweet:      &twitterapi.Tweet{ID: "101", Text: "bar", CreatedAt: createdAt},
+			wantCount:         1,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			var mockStore mocks.Store
+			mockStore.On("GetLastElonTweet", mock.Anything).Return(store.ElonTweet{}, tc.lastKnownTweetErr)
+			mockStore.
+				On("UpsertElonTweet", mock.Anything, mock.MatchedBy(func(params store.UpsertElonTweetParams) bool {
+					return params.TwitterID == 101 && params.Text == "bar" && params.PostedAt.Equal(createdAt) && params.ProcessedAt.Valid
+				})).
+				Return(store.ElonTweet{}, tc.insertTweetErr)
+
+			var mockAPIClient mocks.TwitterAPIClient
+			mockAPIClient.On("GetLastTweet", "44196397").Return(tc.fetchedTweet, tc.fetchedTweetErr)
+			if tc.wantErr == "" {
+				defer mockAPIClient.AssertExpectations(t)
+			}
+
+			updater := daemon.NewTweetPersister(&mockStore, &mockAPIClient, zap.NewNop().Sugar())
+			n, err := updater.PersistTweets(context.Background())
+
+			assert.Equal(t, tc.wantCount, n)
+			if tc.wantErr == "" {
+				assert.NoError(t, err)
+			} else {
+				assert.EqualError(t, err, tc.wantErr)
+			}
+		})
+	}
+}
+
+func TestTweetUpdaterUpdateTweets(t *testing.T) {
+	utcLoc, _ := time.LoadLocation("UTC")
+	createdAt := time.Date(2022, 1, 1, 12, 12, 23, 0, utcLoc)
+
+	lastKnownTweet := store.ElonTweet{TwitterID: 100, Text: "foo", PostedAt: createdAt, CreatedAt: createdAt}
+
+	testCases := []struct {
+		name              string
+		lastKnownTweetErr error
+		fetchedTweets     []*twitterapi.Tweet
+		fetchedTweetsErr  error
+		insertTweetErr    error
+		wantCount         int
+		wantErr           string
+	}{
+		{
+			name:             "error fetching tweets",
+			fetchedTweetsErr: errors.New("whale"),
+			wantCount:        0,
+			wantErr:          "error fetching latest Elon tweets: whale",
+		},
+		{
+			name:           "error inserting tweet",
+			fetchedTweets:  []*twitterapi.Tweet{{ID: "101", Text: "bar", CreatedAt: createdAt}},
+			insertTweetErr: errors.New("database error"),
+			wantCount:      0,
+			wantErr:        "error inserting tweet: error upserting tweet: database error",
+		},
+		{
+			name: "success",
+			fetchedTweets: []*twitterapi.Tweet{
+				{ID: "101", Text: "bar", CreatedAt: createdAt},
+				{ID: "102", Text: "baz", CreatedAt: createdAt},
+				{ID: "103", Text: "qux", CreatedAt: createdAt},
+			},
+			wantCount: 3,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			var mockStore mocks.Store
+			mockStore.On("GetLastElonTweet", mock.Anything).Return(lastKnownTweet, nil)
+			mockStore.
+				On("UpsertElonTweet", mock.Anything, mock.MatchedBy(func(params store.UpsertElonTweetParams) bool {
+					return params.TwitterID == 101 && params.Text == "bar" && params.PostedAt.Equal(createdAt) && !params.ProcessedAt.Valid
+				})).
+				Return(store.ElonTweet{}, tc.insertTweetErr)
+			mockStore.
+				On("UpsertElonTweet", mock.Anything, mock.MatchedBy(func(params store.UpsertElonTweetParams) bool {
+					return params.TwitterID == 102 && params.Text == "baz" && params.PostedAt.Equal(createdAt) && !params.ProcessedAt.Valid
+				})).
+				Return(store.ElonTweet{}, tc.insertTweetErr)
+			mockStore.
+				On("UpsertElonTweet", mock.Anything, mock.MatchedBy(func(params store.UpsertElonTweetParams) bool {
+					return params.TwitterID == 103 && params.Text == "qux" && params.PostedAt.Equal(createdAt) && !params.ProcessedAt.Valid
+				})).
+				Return(store.ElonTweet{}, tc.insertTweetErr)
+			if tc.wantErr == "" {
+				defer mockStore.AssertExpectations(t)
+			}
+
+			var mockAPIClient mocks.TwitterAPIClient
+			mockAPIClient.On("GetTweets", "44196397", "100").Return(tc.fetchedTweets, tc.fetchedTweetsErr)
+			if tc.wantErr == "" {
+				defer mockAPIClient.AssertExpectations(t)
+			}
+
+			updater := daemon.NewTweetPersister(&mockStore, &mockAPIClient, zap.NewNop().Sugar())
+			n, err := updater.PersistTweets(context.Background())
+
+			assert.Equal(t, tc.wantCount, n)
+			if tc.wantErr == "" {
+				assert.NoError(t, err)
+			} else {
+				assert.EqualError(t, err, tc.wantErr)
+			}
+		})
+	}
+}

generated/mocks/Store.go

@@ -37,6 +37,48 @@ func (_m *Store) CreateUser(_a0 context.Context, _a1 store.CreateUserParams) (st
 	return r0, r1
 }
 
+// GetLastElonTweet provides a mock function with given fields: _a0
+func (_m *Store) GetLastElonTweet(_a0 context.Context) (store.ElonTweet, error) {
+	ret := _m.Called(_a0)
+
+	var r0 store.ElonTweet
+	if rf, ok := ret.Get(0).(func(context.Context) store.ElonTweet); ok {
+		r0 = rf(_a0)
+	} else {
+		r0 = ret.Get(0).(store.ElonTweet)
+	}
+
+	var r1 error
+	if rf, ok := ret.Get(1).(func(context.Context) error); ok {
+		r1 = rf(_a0)
+	} else {
+		r1 = ret.Error(1)
+	}
+
+	return r0, r1
+}
+
+// UpsertElonTweet provides a mock function with given fields: _a0, _a1
+func (_m *Store) UpsertElonTweet(_a0 context.Context, _a1 store.UpsertElonTweetParams) (store.ElonTweet, error) {
+	ret := _m.Called(_a0, _a1)
+
+	var r0 store.ElonTweet
+	if rf, ok := ret.Get(0).(func(context.Context, store.UpsertElonTweetParams) store.ElonTweet); ok {
+		r0 = rf(_a0, _a1)
+	} else {
+		r0 = ret.Get(0).(store.ElonTweet)
+	}
+
+	var r1 error
+	if rf, ok := ret.Get(1).(func(context.Context, store.UpsertElonTweetParams) error); ok {
+		r1 = rf(_a0, _a1)
+	} else {
+		r1 = ret.Error(1)
+	}
+
+	return r0, r1
+}
+
 // NewStore creates a new instance of Store. It also registers the testing.TB interface on the mock and a cleanup function to assert the mocks expectations.
 func NewStore(t testing.TB) *Store {
 	mock := &Store{}

generated/mocks/TwitterAPIClient.go

@@ -7,24 +7,47 @@ import (
 
 	mock "github.com/stretchr/testify/mock"
 
-	twitter "git.netflux.io/rob/elon-eats-my-tweets/twitter"
+	twitterapi "git.netflux.io/rob/elon-eats-my-tweets/twitterapi"
 )
 
-// TwitterAPIClient is an autogenerated mock type for the TwitterAPIClient type
+// TwitterAPIClient is an autogenerated mock type for the APIClient type
 type TwitterAPIClient struct {
 	mock.Mock
 }
 
+// GetLastTweet provides a mock function with given fields: _a0
+func (_m *TwitterAPIClient) GetLastTweet(_a0 string) (*twitterapi.Tweet, error) {
+	ret := _m.Called(_a0)
+
+	var r0 *twitterapi.Tweet
+	if rf, ok := ret.Get(0).(func(string) *twitterapi.Tweet); ok {
+		r0 = rf(_a0)
+	} else {
+		if ret.Get(0) != nil {
+			r0 = ret.Get(0).(*twitterapi.Tweet)
+		}
+	}
+
+	var r1 error
+	if rf, ok := ret.Get(1).(func(string) error); ok {
+		r1 = rf(_a0)
+	} else {
+		r1 = ret.Error(1)
+	}
+
+	return r0, r1
+}
+
 // GetMe provides a mock function with given fields:
-func (_m *TwitterAPIClient) GetMe() (*twitter.User, error) {
+func (_m *TwitterAPIClient) GetMe() (*twitterapi.User, error) {
 	ret := _m.Called()
 
-	var r0 *twitter.User
-	if rf, ok := ret.Get(0).(func() *twitter.User); ok {
+	var r0 *twitterapi.User
+	if rf, ok := ret.Get(0).(func() *twitterapi.User); ok {
 		r0 = rf()
 	} else {
 		if ret.Get(0) != nil {
-			r0 = ret.Get(0).(*twitter.User)
+			r0 = ret.Get(0).(*twitterapi.User)
 		}
 	}
 
@@ -38,6 +61,29 @@ func (_m *TwitterAPIClient) GetMe() (*twitter.User, error) {
 	return r0, r1
 }
 
+// GetTweets provides a mock function with given fields: _a0, _a1
+func (_m *TwitterAPIClient) GetTweets(_a0 string, _a1 string) ([]*twitterapi.Tweet, error) {
+	ret := _m.Called(_a0, _a1)
+
+	var r0 []*twitterapi.Tweet
+	if rf, ok := ret.Get(0).(func(string, string) []*twitterapi.Tweet); ok {
+		r0 = rf(_a0, _a1)
+	} else {
+		if ret.Get(0) != nil {
+			r0 = ret.Get(0).([]*twitterapi.Tweet)
+		}
+	}
+
+	var r1 error
+	if rf, ok := ret.Get(1).(func(string, string) error); ok {
+		r1 = rf(_a0, _a1)
+	} else {
+		r1 = ret.Error(1)
+	}
+
+	return r0, r1
+}
+
 // NewTwitterAPIClient creates a new instance of TwitterAPIClient. It also registers the testing.TB interface on the mock and a cleanup function to assert the mocks expectations.
 func NewTwitterAPIClient(t testing.TB) *TwitterAPIClient {
 	mock := &TwitterAPIClient{}

generated/store/models.go

@@ -5,11 +5,22 @@
 package store
 
 import (
+	"database/sql"
 	"time"
 
 	"github.com/google/uuid"
 )
 
+type ElonTweet struct {
+	ID          uuid.UUID
+	TwitterID   int64
+	Text        string
+	PostedAt    time.Time
+	ProcessedAt sql.NullTime
+	CreatedAt   time.Time
+	UpdatedAt   time.Time
+}
+
 type User struct {
 	ID                          uuid.UUID
 	TwitterID                   string

generated/store/queries.sql.go

@@ -7,6 +7,7 @@ package store
 
 import (
 	"context"
+	"database/sql"
 	"time"
 )
 
@@ -55,6 +56,25 @@ func (q *Queries) CreateUser(ctx context.Context, arg CreateUserParams) (User, e
 	return i, err
 }
 
+const getLastElonTweet = `-- name: GetLastElonTweet :one
+SELECT id, twitter_id, text, posted_at, processed_at, created_at, updated_at from elon_tweets ORDER BY twitter_id DESC LIMIT 1
+`
+
+func (q *Queries) GetLastElonTweet(ctx context.Context) (ElonTweet, error) {
+	row := q.db.QueryRow(ctx, getLastElonTweet)
+	var i ElonTweet
+	err := row.Scan(
+		&i.ID,
+		&i.TwitterID,
+		&i.Text,
+		&i.PostedAt,
+		&i.ProcessedAt,
+		&i.CreatedAt,
+		&i.UpdatedAt,
+	)
+	return i, err
+}
+
 const getUserByTwitterID = `-- name: GetUserByTwitterID :one
 SELECT id, twitter_id, username, name, access_token, refresh_token, delete_tweets_enabled, delete_tweets_num_per_iteration, created_at, updated_at FROM users WHERE twitter_id = $1
 `
@@ -76,3 +96,37 @@ func (q *Queries) GetUserByTwitterID(ctx context.Context, twitterID string) (Use
 	)
 	return i, err
 }
+
+const upsertElonTweet = `-- name: UpsertElonTweet :one
+INSERT INTO elon_tweets (twitter_id, text, posted_at, processed_at, created_at, updated_at)
+  VALUES ($1, $2, $3, $4, NOW(), NOW())
+  ON CONFLICT (twitter_id) DO NOTHING
+  RETURNING id, twitter_id, text, posted_at, processed_at, created_at, updated_at
+`
+
+type UpsertElonTweetParams struct {
+	TwitterID   int64
+	Text        string
+	PostedAt    time.Time
+	ProcessedAt sql.NullTime
+}
+
+func (q *Queries) UpsertElonTweet(ctx context.Context, arg UpsertElonTweetParams) (ElonTweet, error) {
+	row := q.db.QueryRow(ctx, upsertElonTweet,
+		arg.TwitterID,
+		arg.Text,
+		arg.PostedAt,
+		arg.ProcessedAt,
+	)
+	var i ElonTweet
+	err := row.Scan(
+		&i.ID,
+		&i.TwitterID,
+		&i.Text,
+		&i.PostedAt,
+		&i.ProcessedAt,
+		&i.CreatedAt,
+		&i.UpdatedAt,
+	)
+	return i, err
+}

httpserver/handler.go

@@ -1,7 +1,6 @@
 package httpserver
 
 //go:generate mockery --recursive --srcpkg github.com/gorilla/sessions --name Store --structname SessionStore --filename SessionStore.go --output ../generated/mocks
-//go:generate mockery --recursive --name TwitterAPIClient --filename TwitterAPIClient.go --output ../generated/mocks
 
 import (
 	"context"
@@ -13,7 +12,7 @@ import (
 	"git.netflux.io/rob/elon-eats-my-tweets/config"
 	"git.netflux.io/rob/elon-eats-my-tweets/generated/store"
 	"git.netflux.io/rob/elon-eats-my-tweets/templates"
-	"git.netflux.io/rob/elon-eats-my-tweets/twitter"
+	"git.netflux.io/rob/elon-eats-my-tweets/twitterapi"
 	"github.com/go-chi/chi"
 	"github.com/go-chi/chi/middleware"
 	"github.com/google/uuid"
@@ -59,12 +58,12 @@ func getCurrentUser(r *http.Request, sessionStore sessions.Store) (CurrentUser,
 }
 
 type TwitterAPIClient interface {
-	GetMe() (*twitter.User, error)
+	GetMe() (*twitterapi.User, error)
 }
 
 type handler struct {
-	store                twitter.Store
-	twitterAPIClientFunc func(c *http.Client) TwitterAPIClient
+	store                twitterapi.Store
+	twitterAPIClientFunc func(c *http.Client) twitterapi.APIClient
 	oauth2Config         *oauth2.Config
 	renderer             *templates.Renderer
 	sessionStore         sessions.Store
@@ -72,7 +71,7 @@ type handler struct {
 	logger               *zap.SugaredLogger
 }
 
-func NewHandler(cfg config.Config, store twitter.Store, twitterAPIClientFunc func(c *http.Client) TwitterAPIClient, sessionStore sessions.Store, tokenGenerator TokenGenerator, logger *zap.Logger) http.Handler {
+func NewHandler(cfg config.Config, store twitterapi.Store, twitterAPIClientFunc func(c *http.Client) twitterapi.APIClient, sessionStore sessions.Store, tokenGenerator TokenGenerator, logger *zap.Logger) http.Handler {
 	r := chi.NewRouter()
 	r.Use(middleware.RequestID)
 	r.Use(middleware.RealIP)

httpserver/handler_test.go

@@ -11,7 +11,7 @@ import (
 	"git.netflux.io/rob/elon-eats-my-tweets/generated/mocks"
 	"git.netflux.io/rob/elon-eats-my-tweets/generated/store"
 	"git.netflux.io/rob/elon-eats-my-tweets/httpserver"
-	"git.netflux.io/rob/elon-eats-my-tweets/twitter"
+	"git.netflux.io/rob/elon-eats-my-tweets/twitterapi"
 	"github.com/google/uuid"
 	"github.com/gorilla/sessions"
 	"github.com/stretchr/testify/assert"
@@ -67,7 +67,7 @@ func TestGetIndex(t *testing.T) {
 			handler := httpserver.NewHandler(
 				config.Config{},
 				&mocks.Store{},
-				func(*http.Client) httpserver.TwitterAPIClient { return &mocks.TwitterAPIClient{} },
+				func(*http.Client) twitterapi.APIClient { return &mocks.TwitterAPIClient{} },
 				&mockSessionStore,
 				&mockTokenGenerator{},
 				zap.NewNop(),
@@ -124,7 +124,7 @@ func TestGetLogin(t *testing.T) {
 					},
 				},
 				&mocks.Store{},
-				func(*http.Client) httpserver.TwitterAPIClient { return &mocks.TwitterAPIClient{} },
+				func(*http.Client) twitterapi.APIClient { return &mocks.TwitterAPIClient{} },
 				&mockSessionStore,
 				&mockTokenGenerator{tokens: []string{"state", "pkceVerifier"}},
 				zap.NewNop(),
@@ -268,7 +268,7 @@ func TestGetCallback(t *testing.T) {
 			mockSessionStore.On("Save", mock.Anything, mock.Anything, sess).Return(tc.sessionSaveError)
 
 			var mockTwitterClient mocks.TwitterAPIClient
-			mockTwitterClient.On("GetMe").Return(&twitter.User{ID: "1", Name: "foo", Username: "Foo Bar"}, tc.getTwitterUserError)
+			mockTwitterClient.On("GetMe").Return(&twitterapi.User{ID: "1", Name: "foo", Username: "Foo Bar"}, tc.getTwitterUserError)
 
 			var mockStore mocks.Store
 			mockStore.On("CreateUser", mock.Anything, mock.MatchedBy(func(params store.CreateUserParams) bool {
@@ -304,7 +304,7 @@ func TestGetCallback(t *testing.T) {
 					},
 				},
 				&mockStore,
-				func(*http.Client) httpserver.TwitterAPIClient { return &mockTwitterClient },
+				func(*http.Client) twitterapi.APIClient { return &mockTwitterClient },
 				&mockSessionStore,
 				nil,
 				zap.NewNop(),
@@ -339,7 +339,7 @@ func TestPostLogout(t *testing.T) {
 	handler := httpserver.NewHandler(
 		config.Config{},
 		&mocks.Store{},
-		func(*http.Client) httpserver.TwitterAPIClient { return &mocks.TwitterAPIClient{} },
+		func(*http.Client) twitterapi.APIClient { return &mocks.TwitterAPIClient{} },
 		&mockSessionStore,
 		nil,
 		zap.NewNop(),

main.go

@@ -8,9 +8,10 @@ import (
 	"net/http"
 
 	"git.netflux.io/rob/elon-eats-my-tweets/config"
+	"git.netflux.io/rob/elon-eats-my-tweets/daemon"
 	"git.netflux.io/rob/elon-eats-my-tweets/generated/store"
 	"git.netflux.io/rob/elon-eats-my-tweets/httpserver"
-	"git.netflux.io/rob/elon-eats-my-tweets/twitter"
+	"git.netflux.io/rob/elon-eats-my-tweets/twitterapi"
 	"github.com/gorilla/sessions"
 	"github.com/jackc/pgx/v4/pgxpool"
 	"go.uber.org/zap"
@@ -35,10 +36,18 @@ func main() {
 	defer dbconn.Close()
 	store := store.New(dbconn)
 
+	// TODO: separate daemon and webserver in separate binaries (or via flags).
+	go daemon.Run(
+		context.Background(),
+		store,
+		twitterapi.NewClientWithBearerToken(cfg.Twitter.BearerToken),
+		logger.Sugar().Named("daemon"),
+	)
+
 	handler := httpserver.NewHandler(
 		cfg,
 		store,
-		func(c *http.Client) httpserver.TwitterAPIClient { return twitter.NewAPIClient(c) },
+		func(c *http.Client) twitterapi.APIClient { return twitterapi.NewClient(c) },
 		sessions.NewCookieStore([]byte(cfg.SessionKey)),
 		httpserver.RandomTokenGenerator{},
 		logger,

sql/migrations/20220523031402_add_elon_tweets_table.down.sql

@@ -0,0 +1 @@
+DROP TABLE elon_tweets;

sql/migrations/20220523031402_add_elon_tweets_table.up.sql

@@ -0,0 +1,11 @@
+CREATE TABLE elon_tweets (
+  id uuid PRIMARY KEY DEFAULT gen_random_uuid(), 
+  twitter_id bigint NOT NULL,
+  text TEXT NOT NULL,
+  posted_at TIMESTAMP WITH TIME ZONE NOT NULL,
+  processed_at TIMESTAMP WITH TIME ZONE,
+  created_at TIMESTAMP WITH TIME ZONE NOT NULL,
+  updated_at TIMESTAMP WITH TIME ZONE NOT NULL
+);
+
+CREATE UNIQUE INDEX index_elon_tweets_on_twitter_id ON elon_tweets (twitter_id);

sql/queries.sql

@@ -8,3 +8,12 @@ INSERT INTO users (twitter_id, username, name, access_token, refresh_token, crea
 
 -- name: GetUserByTwitterID :one
 SELECT * FROM users WHERE twitter_id = $1;
+
+-- name: GetLastElonTweet :one
+SELECT * from elon_tweets ORDER BY twitter_id DESC LIMIT 1;
+
+-- name: UpsertElonTweet :one
+INSERT INTO elon_tweets (twitter_id, text, posted_at, processed_at, created_at, updated_at)
+  VALUES ($1, $2, $3, $4, NOW(), NOW())
+  ON CONFLICT (twitter_id) DO NOTHING
+  RETURNING *;

twitter/types.go

@@ -1,13 +0,0 @@
-package twitter
-
-//go:generate mockery --recursive --name Store --output ../generated/mocks
-
-import (
-	"context"
-
-	"git.netflux.io/rob/elon-eats-my-tweets/generated/store"
-)
-
-type Store interface {
-	CreateUser(context.Context, store.CreateUserParams) (store.User, error)
-}

twitterapi/client.go

@@ -1,28 +1,34 @@
-package twitter
-
-//go:generate mockery --recursive --name Getter --output ../generated/mocks
+package twitterapi
 
 import (
 	"encoding/json"
+	"errors"
 	"fmt"
 	"net/http"
 	"time"
 )
 
-// ElonID is the Twitter ID of @elonmusk.
-const ElonID = "44196397"
-
-// User represents a Twitter user.
-type User struct {
-	ID       string
-	Name     string
-	Username string
+type Getter interface {
+	Get(string) (*http.Response, error)
 }
 
-// Tweet represents a tweet.
-type Tweet struct {
-	ID   string
-	Text string
+// NewClient returns a new APIClient.
+func NewClient(httpclient Getter) APIClient {
+	return &apiClient{httpclient}
+}
+
+// NewAPIClient returns a new APIClient which will authenticate with the
+// provided bearer token.
+func NewClientWithBearerToken(bearerToken string) APIClient {
+	return &apiClient{&http.Client{
+		Timeout:   time.Second * 5,
+		Transport: &bearerTokenTransport{bearerToken: bearerToken},
+	}}
+}
+
+// apiClient implements APIClient.
+type apiClient struct {
+	Getter
 }
 
 // bearerTokenTransport implements http.RoundTripper.
@@ -55,31 +61,8 @@ func cloneRequest(r *http.Request) *http.Request {
 	return r2
 }
 
-type Getter interface {
-	Get(string) (*http.Response, error)
-}
-
-// NewAPIClient returns a new APIClient.
-func NewAPIClient(httpclient Getter) *APIClient {
-	return &APIClient{httpclient}
-}
-
-// NewAPIClient returns a new APIClient which will authenticate with the
-// provided bearer token.
-func NewAPIClientWithBearerToken(bearerToken string) *APIClient {
-	return &APIClient{&http.Client{
-		Timeout:   time.Second * 5,
-		Transport: &bearerTokenTransport{bearerToken: bearerToken},
-	}}
-}
-
-// APIClient interacts with the Twitter API V2.
-type APIClient struct {
-	Getter
-}
-
 // GetMe returns the currently authenticated user.
-func (c *APIClient) GetMe() (*User, error) {
+func (c *apiClient) GetMe() (*User, error) {
 	type oauthResponse struct {
 		Data *User `json:"data"`
 	}
@@ -101,13 +84,61 @@ func (c *APIClient) GetMe() (*User, error) {
 	return oauthResp.Data, nil
 }
 
-// GetElonTweets returns the latest tweets for a given user.
-func (c *APIClient) GetTweets(userID string, sinceID string) ([]*Tweet, error) {
+var ErrNoTweets = errors.New("no tweets available")
+
+// GetLastTweet returns the most recent tweet for a given user. If no tweets
+// are available, ErrNoTweets will be returned.
+func (c *apiClient) GetLastTweet(userID string) (*Tweet, error) {
+	type oauthResponse struct {
+		Data []*Tweet        `json:"data"`
+		Meta TwitterMetadata `json:"meta"`
+	}
+
+	apiURL := "https://api.twitter.com/2/users/" + userID + "/tweets?tweet.fields=created_at"
+
+	resp, err := c.Get(apiURL)
+	if err != nil {
+		return nil, fmt.Errorf("error fetching resource: %v", err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("error fetching resource: status code %d", resp.StatusCode)
+	}
+
+	var oauthResp oauthResponse
+	if err = json.NewDecoder(resp.Body).Decode(&oauthResp); err != nil {
+		return nil, fmt.Errorf("error decoding resource: %v", err)
+	}
+
+	if oauthResp.Meta.ResultCount == 0 {
+		return nil, ErrNoTweets
+	}
+
+	// the order of returned tweets seems to be chronological, but it isn't
+	// documented so use the metadata instead.
+	for _, tweet := range oauthResp.Data {
+		if tweet.ID == oauthResp.Meta.NewestID {
+			return tweet, nil
+		}
+	}
+
+	return nil, errors.New("error fetching latest tweet: could not match newest_id")
+}
+
+// GetTweets returns the latest tweets for a given user, up to the maximum
+// batch size of 100 allowable by the Twitter API.
+func (c *apiClient) GetTweets(userID string, sinceID string) ([]*Tweet, error) {
 	type oauthResponse struct {
 		Data []*Tweet `json:"data"`
 	}
 
-	resp, err := c.Get(fmt.Sprintf("https://api.twitter.com/2/users/%s/tweets?since_id=%s", userID, sinceID))
+	apiURL := "https://api.twitter.com/2/users/" + userID + "/tweets?tweet.fields=created_at&max_results=100"
+	if sinceID == "" {
+	} else {
+		apiURL += "&since_id=" + sinceID
+	}
+
+	resp, err := c.Get(apiURL)
 	if err != nil {
 		return nil, fmt.Errorf("error fetching resource: %v", err)
 	}

twitterapi/client_test.go

@@ -1,4 +1,6 @@
-package twitter_test
+package twitterapi_test
+
+//go:generate mockery --recursive --name Getter --output ../generated/mocks
 
 import (
 	"errors"
@@ -6,9 +8,10 @@ import (
 	"net/http"
 	"strings"
 	"testing"
+	"time"
 
 	"git.netflux.io/rob/elon-eats-my-tweets/generated/mocks"
-	"git.netflux.io/rob/elon-eats-my-tweets/twitter"
+	"git.netflux.io/rob/elon-eats-my-tweets/twitterapi"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -18,14 +21,14 @@ func TestGetMe(t *testing.T) {
 		responseStatusCode int
 		responseBody       io.Reader
 		responseErr        error
-		wantUser           *twitter.User
+		wantUser           *twitterapi.User
 		wantErr            string
 	}{
 		{
 			name:               "successful request",
 			responseStatusCode: 200,
 			responseBody:       strings.NewReader(`{"Data": {"id": "1", "name": "foo", "username": "foo bar"}}`),
-			wantUser:           &twitter.User{ID: "1", Name: "foo", Username: "foo bar"},
+			wantUser:           &twitterapi.User{ID: "1", Name: "foo", Username: "foo bar"},
 		},
 		{
 			name:        "network error",
@@ -54,7 +57,7 @@ func TestGetMe(t *testing.T) {
 			getter.
 				On("Get", "https://api.twitter.com/2/users/me").
 				Return(&http.Response{StatusCode: tc.responseStatusCode, Body: io.NopCloser(tc.responseBody)}, tc.responseErr)
-			client := twitter.NewAPIClient(&getter)
+			client := twitterapi.NewClient(&getter)
 
 			user, err := client.GetMe()
 			assert.Equal(t, tc.wantUser, user)
@@ -69,32 +72,50 @@ func TestGetMe(t *testing.T) {
 }
 
 func TestGetTweets(t *testing.T) {
-	const (
-		userID  = "1"
-		sinceID = "2"
-	)
+	const userID = "1"
+	utcLoc, _ := time.LoadLocation("UTC")
+
 	testCases := []struct {
 		name               string
+		sinceID            string
+		wantAPIURL         string
 		responseStatusCode int
 		responseBody       io.Reader
 		responseErr        error
-		wantTweets         []*twitter.Tweet
+		wantTweets         []*twitterapi.Tweet
 		wantErr            string
 	}{
 		{
-			name:               "successful request",
+			name:               "successful request, empty since_id",
+			wantAPIURL:         "https://api.twitter.com/2/users/" + userID + "/tweets?tweet.fields=created_at&max_results=100",
 			responseStatusCode: 200,
-			responseBody:       strings.NewReader(`{"Data": [{"id": "101", "text": "foo"}, {"id": "102", "text": "bar"}]}`),
-			wantTweets:         []*twitter.Tweet{{ID: "101", Text: "foo"}, {ID: "102", Text: "bar"}},
+			responseBody:       strings.NewReader(`{"Data": [{"id": "101", "text": "foo", "created_at": "2019-06-04T23:12:08.000Z"}, {"id": "102", "text": "bar", "created_at": "2019-06-04T23:12:08.000Z"}]}`),
+			wantTweets: []*twitterapi.Tweet{
+				{ID: "101", Text: "foo", CreatedAt: time.Date(2019, 6, 4, 23, 12, 8, 0, utcLoc)},
+				{ID: "102", Text: "bar", CreatedAt: time.Date(2019, 6, 4, 23, 12, 8, 0, utcLoc)},
+			},
+		},
+		{
+			name:               "successful request, non-empty since_id",
+			sinceID:            "2",
+			wantAPIURL:         "https://api.twitter.com/2/users/" + userID + "/tweets?tweet.fields=created_at&max_results=100&since_id=2",
+			responseStatusCode: 200,
+			responseBody:       strings.NewReader(`{"Data": [{"id": "101", "text": "foo", "created_at": "2019-06-04T23:12:08.000Z"}, {"id": "102", "text": "bar", "created_at": "2019-06-04T23:12:08.000Z"}]}`),
+			wantTweets: []*twitterapi.Tweet{
+				{ID: "101", Text: "foo", CreatedAt: time.Date(2019, 6, 4, 23, 12, 8, 0, utcLoc)},
+				{ID: "102", Text: "bar", CreatedAt: time.Date(2019, 6, 4, 23, 12, 8, 0, utcLoc)},
+			},
 		},
 		{
 			name:        "network error",
+			wantAPIURL:  "https://api.twitter.com/2/users/" + userID + "/tweets?tweet.fields=created_at&max_results=100",
 			responseErr: errors.New("network error"),
 			wantTweets:  nil,
 			wantErr:     "error fetching resource: network error",
 		},
 		{
 			name:               "500 response",
+			wantAPIURL:         "https://api.twitter.com/2/users/" + userID + "/tweets?tweet.fields=created_at&max_results=100",
 			responseStatusCode: 500,
 			responseBody:       strings.NewReader("whale"),
 			wantTweets:         nil,
@@ -102,6 +123,7 @@ func TestGetTweets(t *testing.T) {
 		},
 		{
 			name:               "decoder error",
+			wantAPIURL:         "https://api.twitter.com/2/users/" + userID + "/tweets?tweet.fields=created_at&max_results=100",
 			responseStatusCode: 200,
 			responseBody:       strings.NewReader("<html></html>"),
 			wantTweets:         nil,
@@ -113,13 +135,13 @@ func TestGetTweets(t *testing.T) {
 		t.Run(tc.name, func(t *testing.T) {
 			var getter mocks.Getter
 			getter.
-				On("Get", "https://api.twitter.com/2/users/"+userID+"/tweets?since_id="+sinceID).
+				On("Get", tc.wantAPIURL).
 				Return(&http.Response{StatusCode: tc.responseStatusCode, Body: io.NopCloser(tc.responseBody)}, tc.responseErr)
-			client := twitter.NewAPIClient(&getter)
+			client := twitterapi.NewClient(&getter)
+
+			tweets, err := client.GetTweets(userID, tc.sinceID)
 
-			tweets, err := client.GetTweets(userID, sinceID)
 			assert.Equal(t, tc.wantTweets, tweets)
-
 			if tc.wantErr == "" {
 				assert.NoError(t, err)
 			} else {

twitterapi/types.go

@@ -0,0 +1,45 @@
+package twitterapi
+
+//go:generate mockery --recursive --name Store --output ../generated/mocks
+//go:generate mockery --recursive --name APIClient --structname TwitterAPIClient --filename TwitterAPIClient.go --output ../generated/mocks
+
+import (
+	"context"
+	"time"
+
+	"git.netflux.io/rob/elon-eats-my-tweets/generated/store"
+)
+
+// Store is a persistent store.
+type Store interface {
+	CreateUser(context.Context, store.CreateUserParams) (store.User, error)
+	GetLastElonTweet(context.Context) (store.ElonTweet, error)
+	UpsertElonTweet(context.Context, store.UpsertElonTweetParams) (store.ElonTweet, error)
+}
+
+// APIClient is a client for the Twitter API.
+type APIClient interface {
+	GetLastTweet(string) (*Tweet, error)
+	GetTweets(string, string) ([]*Tweet, error)
+	GetMe() (*User, error)
+}
+
+// TwitterMetadata contains the metadata returned in Twitter API responses.
+type TwitterMetadata struct {
+	ResultCount int    `json:"result_count"`
+	NewestID    string `json:"newest_id"`
+}
+
+// User represents a Twitter user as returned from the Twitter API.
+type User struct {
+	ID       string `json:"id"`
+	Name     string `json:"name"`
+	Username string `json:"username"`
+}
+
+// Tweet represents a tweet as returned from the Twitter API.
+type Tweet struct {
+	ID        string    `json:"id"`
+	Text      string    `json:"text"`
+	CreatedAt time.Time `json:"created_at"`
+}