From 4f01edb9230f58ff84b0dd892c931ec8ac9aad55 Mon Sep 17 00:00:00 2001 From: Brian Picciano Date: Tue, 13 Sep 2022 12:56:08 +0200 Subject: move src out of srv, clean up default.nix and Makefile --- src/post/post.go | 368 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 368 insertions(+) create mode 100644 src/post/post.go (limited to 'src/post/post.go') diff --git a/src/post/post.go b/src/post/post.go new file mode 100644 index 0000000..03bce6c --- /dev/null +++ b/src/post/post.go @@ -0,0 +1,368 @@ +// Package post deals with the storage and rendering of blog posts. +package post + +import ( + "database/sql" + "errors" + "fmt" + "regexp" + "strings" + "time" +) + +var ( + // ErrPostNotFound is used to indicate a Post could not be found in the + // Store. + ErrPostNotFound = errors.New("post not found") +) + +var titleCleanRegexp = regexp.MustCompile(`[^a-z ]`) + +// NewID generates a (hopefully) unique ID based on the given title. +func NewID(title string) string { + title = strings.ToLower(title) + title = titleCleanRegexp.ReplaceAllString(title, "") + title = strings.ReplaceAll(title, " ", "-") + return title +} + +// Post contains all information having to do with a blog post. +type Post struct { + ID string + Title string + Description string + Tags []string // only alphanumeric supported + Series string + Body string +} + +// StoredPost is a Post which has been stored in a Store, and has been given +// some extra fields as a result. +type StoredPost struct { + Post + + PublishedAt time.Time + LastUpdatedAt time.Time +} + +// Store is used for storing posts to a persistent storage. +type Store interface { + + // Set sets the Post data into the storage, keyed by the Post's ID. If there + // was not a previously existing Post with the same ID then Set returns + // true. It overwrites the previous Post with the same ID otherwise. + Set(post Post, now time.Time) (bool, error) + + // Get returns count StoredPosts, sorted time descending, offset by the + // given page number. The returned boolean indicates if there are more pages + // or not. + Get(page, count int) ([]StoredPost, bool, error) + + // GetByID will return the StoredPost with the given ID, or ErrPostNotFound. + GetByID(id string) (StoredPost, error) + + // GetBySeries returns all StoredPosts with the given series, sorted time + // descending, or empty slice. + GetBySeries(series string) ([]StoredPost, error) + + // GetByTag returns all StoredPosts with the given tag, sorted time + // descending, or empty slice. + GetByTag(tag string) ([]StoredPost, error) + + // GetTags returns all tags which have at least one Post using them. + GetTags() ([]string, error) + + // Delete will delete the StoredPost with the given ID. + Delete(id string) error +} + +type store struct { + db *SQLDB +} + +// NewStore initializes a new Store using an existing SQLDB. +func NewStore(db *SQLDB) Store { + return &store{ + db: db, + } +} + +func (s *store) Set(post Post, now time.Time) (bool, error) { + + if post.ID == "" { + return false, errors.New("post ID can't be empty") + } + + var first bool + + err := s.db.withTx(func(tx *sql.Tx) error { + + nowTS := now.Unix() + + nowSQL := sql.NullInt64{Int64: nowTS, Valid: !now.IsZero()} + + _, err := tx.Exec( + `INSERT INTO posts ( + id, title, description, series, published_at, body + ) + VALUES + (?, ?, ?, ?, ?, ?) + ON CONFLICT (id) DO UPDATE SET + title=excluded.title, + description=excluded.description, + series=excluded.series, + last_updated_at=?, + body=excluded.body`, + post.ID, + post.Title, + post.Description, + &sql.NullString{String: post.Series, Valid: post.Series != ""}, + nowSQL, + post.Body, + nowSQL, + ) + + if err != nil { + return fmt.Errorf("inserting into posts: %w", err) + } + + // this is a bit of a hack, but it allows us to update the tagset without + // doing a diff. + _, err = tx.Exec(`DELETE FROM post_tags WHERE post_id = ?`, post.ID) + + if err != nil { + return fmt.Errorf("clearning post tags: %w", err) + } + + for _, tag := range post.Tags { + + _, err = tx.Exec( + `INSERT INTO post_tags (post_id, tag) VALUES (?, ?) + ON CONFLICT DO NOTHING`, + post.ID, + tag, + ) + + if err != nil { + return fmt.Errorf("inserting tag %q: %w", tag, err) + } + } + + err = tx.QueryRow( + `SELECT 1 FROM posts WHERE id=? AND last_updated_at IS NULL`, + post.ID, + ).Scan(new(int)) + + first = !errors.Is(err, sql.ErrNoRows) + + return nil + }) + + return first, err +} + +func (s *store) get( + querier interface { + Query(string, ...interface{}) (*sql.Rows, error) + }, + limit, offset int, + where string, whereArgs ...interface{}, +) ( + []StoredPost, error, +) { + + query := ` + SELECT + p.id, p.title, p.description, p.series, GROUP_CONCAT(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 + ` + GROUP BY (p.id) + ORDER BY p.published_at DESC, p.title DESC` + + if limit > 0 { + query += fmt.Sprintf(" LIMIT %d", limit) + } + + if offset > 0 { + query += fmt.Sprintf(" OFFSET %d", offset) + } + + rows, err := querier.Query(query, whereArgs...) + + if err != nil { + return nil, fmt.Errorf("selecting: %w", err) + } + + var posts []StoredPost + + for rows.Next() { + + var ( + post StoredPost + series, tag sql.NullString + publishedAt, lastUpdatedAt sql.NullInt64 + ) + + err := rows.Scan( + &post.ID, &post.Title, &post.Description, &series, &tag, + &publishedAt, &lastUpdatedAt, + &post.Body, + ) + + if err != nil { + return nil, fmt.Errorf("scanning row: %w", err) + } + + post.Series = series.String + + if tag.String != "" { + post.Tags = strings.Split(tag.String, ",") + } + + if publishedAt.Valid { + post.PublishedAt = time.Unix(publishedAt.Int64, 0).UTC() + } + + if lastUpdatedAt.Valid { + post.LastUpdatedAt = time.Unix(lastUpdatedAt.Int64, 0).UTC() + } + + posts = append(posts, post) + } + + if err := rows.Close(); err != nil { + return nil, fmt.Errorf("closing row iterator: %w", err) + } + + return posts, nil +} + +func (s *store) Get(page, count int) ([]StoredPost, bool, error) { + + posts, err := s.get(s.db.db, count+1, page*count, ``) + + if err != nil { + return nil, false, fmt.Errorf("querying posts: %w", err) + } + + var hasMore bool + + if len(posts) > count { + hasMore = true + posts = posts[:count] + } + + return posts, hasMore, nil +} + +func (s *store) GetByID(id string) (StoredPost, error) { + + posts, err := s.get(s.db.db, 0, 0, `WHERE p.id=?`, id) + + if err != nil { + return StoredPost{}, fmt.Errorf("querying posts: %w", err) + } + + if len(posts) == 0 { + return StoredPost{}, ErrPostNotFound + } + + if len(posts) > 1 { + panic(fmt.Sprintf("got back multiple posts querying id %q: %+v", id, posts)) + } + + return posts[0], nil +} + +func (s *store) GetBySeries(series string) ([]StoredPost, error) { + return s.get(s.db.db, 0, 0, `WHERE p.series=?`, series) +} + +func (s *store) GetByTag(tag string) ([]StoredPost, error) { + + var posts []StoredPost + + err := s.db.withTx(func(tx *sql.Tx) error { + + rows, err := tx.Query(`SELECT post_id FROM post_tags WHERE tag = ?`, tag) + + if err != nil { + return fmt.Errorf("querying post_tags by tag: %w", err) + } + + var ( + placeholders []string + whereArgs []interface{} + ) + + for rows.Next() { + + var id string + + if err := rows.Scan(&id); err != nil { + rows.Close() + return fmt.Errorf("scanning id: %w", err) + } + + whereArgs = append(whereArgs, id) + placeholders = append(placeholders, "?") + } + + if err := rows.Close(); err != nil { + return fmt.Errorf("closing row iterator: %w", err) + } + + where := fmt.Sprintf("WHERE p.id IN (%s)", strings.Join(placeholders, ",")) + + if posts, err = s.get(tx, 0, 0, where, whereArgs...); err != nil { + return fmt.Errorf("querying for ids %+v: %w", whereArgs, err) + } + + return nil + }) + + return posts, err +} + +func (s *store) GetTags() ([]string, error) { + + rows, err := s.db.db.Query(`SELECT tag FROM post_tags GROUP BY tag`) + if err != nil { + return nil, fmt.Errorf("querying all tags: %w", err) + } + defer rows.Close() + + var tags []string + + for rows.Next() { + + var tag string + + if err := rows.Scan(&tag); err != nil { + return nil, fmt.Errorf("scanning tag: %w", err) + } + + tags = append(tags, tag) + } + + return tags, nil +} + +func (s *store) Delete(id string) error { + + return s.db.withTx(func(tx *sql.Tx) error { + + if _, err := tx.Exec(`DELETE FROM post_tags WHERE post_id = ?`, id); err != nil { + return fmt.Errorf("deleting from post_tags: %w", err) + } + + if _, err := tx.Exec(`DELETE FROM posts WHERE id = ?`, id); err != nil { + return fmt.Errorf("deleting from posts: %w", err) + } + + return nil + }) +} -- cgit v1.2.3