From e24dd6d630cf558c616c1252bacfff6d343b4194 Mon Sep 17 00:00:00 2001
From: Brian Picciano <mediocregopher@gmail.com>
Date: Sat, 14 May 2022 20:42:43 -0600
Subject: Import posts in dev-shell target

---
 srv/src/post/post.go      | 26 ++++++++++++++++++++------
 srv/src/post/post_test.go | 41 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 61 insertions(+), 6 deletions(-)

(limited to 'srv/src/post')

diff --git a/srv/src/post/post.go b/srv/src/post/post.go
index 30ded15..cadfcfc 100644
--- a/srv/src/post/post.go
+++ b/srv/src/post/post.go
@@ -74,21 +74,33 @@ type Store interface {
 	// ascending, or empty slice.
 	GetByTag(tag string) ([]StoredPost, error)
 
+	// WithOrderDesc will return a Store whose Get operations return Posts in
+	// time descending order, rather than ascending.
+	WithOrderDesc() Store
+
 	// Delete will delete the StoredPost with the given ID.
 	Delete(id string) error
 }
 
 type store struct {
-	db *sql.DB
+	db    *sql.DB
+	order string
 }
 
 // NewStore initializes a new Store using an existing SQLDB.
 func NewStore(db *SQLDB) Store {
 	return &store{
-		db: db.db,
+		db:    db.db,
+		order: "ASC",
 	}
 }
 
+func (s *store) WithOrderDesc() Store {
+	s2 := *s
+	s2.order = "DESC"
+	return &s2
+}
+
 // if the callback returns an error then the transaction is aborted.
 func (s *store) withTx(cb func(*sql.Tx) error) error {
 
@@ -185,15 +197,17 @@ func (s *store) get(
 	[]StoredPost, error,
 ) {
 
-	query := `
-		SELECT
+	query := fmt.Sprintf(
+		`SELECT
 			p.id, p.title, p.description, p.series, pt.tag,
 			p.published_at, p.last_updated_at,
 			p.body
 		FROM posts p
 		LEFT JOIN post_tags pt ON (p.id = pt.post_id)
-		` + where + `
-		ORDER BY p.published_at ASC, p.title ASC`
+		`+where+`
+		ORDER BY p.published_at %s, p.title %s`,
+		s.order, s.order,
+	)
 
 	if limit > 0 {
 		query += fmt.Sprintf(" LIMIT %d", limit)
diff --git a/srv/src/post/post_test.go b/srv/src/post/post_test.go
index 55a29ea..c5587c8 100644
--- a/srv/src/post/post_test.go
+++ b/srv/src/post/post_test.go
@@ -187,6 +187,47 @@ func TestStore(t *testing.T) {
 		assertPostsEqual(t, posts[4:], gotPosts)
 	})
 
+	t.Run("get_desc", func(t *testing.T) {
+		h := newStoreTestHarness(t)
+		h.store = h.store.WithOrderDesc()
+
+		now := h.clock.Now().UTC()
+
+		posts := []StoredPost{
+			h.testStoredPost(3),
+			h.testStoredPost(2),
+			h.testStoredPost(1),
+			h.testStoredPost(0),
+		}
+
+		for _, post := range posts {
+			assert.NoError(t, h.store.Set(post.Post, now))
+		}
+
+		gotPosts, hasMore, err := h.store.Get(0, 2)
+		assert.NoError(t, err)
+		assert.True(t, hasMore)
+		assertPostsEqual(t, posts[:2], gotPosts)
+
+		gotPosts, hasMore, err = h.store.Get(1, 2)
+		assert.NoError(t, err)
+		assert.False(t, hasMore)
+		assertPostsEqual(t, posts[2:4], gotPosts)
+
+		posts = append([]StoredPost{h.testStoredPost(4)}, posts...)
+		assert.NoError(t, h.store.Set(posts[0].Post, now))
+
+		gotPosts, hasMore, err = h.store.Get(1, 2)
+		assert.NoError(t, err)
+		assert.True(t, hasMore)
+		assertPostsEqual(t, posts[2:4], gotPosts)
+
+		gotPosts, hasMore, err = h.store.Get(2, 2)
+		assert.NoError(t, err)
+		assert.False(t, hasMore)
+		assertPostsEqual(t, posts[4:], gotPosts)
+	})
+
 	t.Run("get_by_series", func(t *testing.T) {
 		h := newStoreTestHarness(t)
 
-- 
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