add endpoints to get single blog article

Signed-off-by: Tobias Erbshäußer <tobias@tesoft.dev>

backend/blog.go

@@ -32,8 +32,8 @@ type ArticleProperties struct {
 
 type Article struct {
 	ArticleProperties
-	Content string
+	Content string        `json:"content"`
-	Files   []ArticleFile
+	Files   []ArticleFile `json:"-"`
 }
 
 type ArticleFile struct {
@@ -230,9 +230,53 @@ func (h *ApiHandler) ServeBlogPut(writer http.ResponseWriter, request *http.Requ
 }
 
 func (h *ApiHandler) ServeBlogGetSingle(writer http.ResponseWriter, request *http.Request) {
-	// TODO
+	idStr := request.PathValue("id")
+	id, err := strconv.ParseInt(idStr, 10, 64)
+	if err != nil {
+		WriteError(writer, http.StatusBadRequest, "invalid id", err)
+		return
+	}
+
+	article, err := h.db.GetBlogArticle(IsAuthorized(request), id)
+	if err != nil {
+		if errors.Is(err, ErrNotFound) {
+			WriteError(writer, http.StatusNotFound, "article not found", nil)
+		} else {
+			WriteError(writer, http.StatusInternalServerError, "failed to query database", err)
+		}
+		return
+	}
+
+	WriteResponse(writer, http.StatusOK, article)
 }
 
 func (h *ApiHandler) ServeBlogFileGetSingle(writer http.ResponseWriter, request *http.Request) {
-	// TODO
+	idStr := request.PathValue("articleId")
+	articleId, err := strconv.ParseInt(idStr, 10, 64)
+	if err != nil {
+		WriteError(writer, http.StatusBadRequest, "invalid article id", err)
+		return
+	}
+
+	idStr = request.PathValue("fileId")
+	fileId, err := strconv.ParseInt(idStr, 10, 64)
+	if err != nil {
+		WriteError(writer, http.StatusBadRequest, "invalid file id", err)
+		return
+	}
+
+	file, err := h.db.GetBlogArticleFile(IsAuthorized(request), articleId, fileId)
+	if err != nil {
+		if errors.Is(err, ErrNotFound) {
+			WriteError(writer, http.StatusNotFound, "article file not found", nil)
+		} else {
+			WriteError(writer, http.StatusInternalServerError, "failed to query database", err)
+		}
+		return
+	}
+
+	_, err = writer.Write(file.Data)
+	if err != nil {
+		log.Println(err)
+	}
 }

backend/db.go

@@ -13,6 +13,8 @@ import (
 	_ "github.com/mattn/go-sqlite3"
 )
 
+var ErrNotFound = errors.New("not found")
+
 type Database struct {
 	db *sql.DB
 }
@@ -203,6 +205,105 @@ func (db *Database) GetBlogArticles(showAll bool, offset int, limit int) ([]Arti
 	return articles, nil
 }
 
+func (db *Database) GetBlogArticle(showAll bool, id int64) (*Article, error) {
+	filter := "WHERE blog_article.id = ?"
+	if !showAll {
+		filter = filter + " AND status = " + strconv.Itoa(ArticleStatusPublished)
+	}
+
+	statement := "SELECT blog_article.status, blog_article.title, blog_article.date, blog_article.modification_date, blog_article.content, blog_tag.name" +
+		" FROM blog_article" +
+		" LEFT JOIN blog_article_to_tag ON blog_article.id = blog_article_to_tag.article_id" +
+		" LEFT JOIN blog_tag ON blog_article_to_tag.tag_id = blog_tag.id" +
+		" " + filter +
+		" ORDER BY blog_tag.name"
+
+	rows, err := db.db.Query(statement, id)
+	if err != nil {
+		return nil, err
+	}
+	defer func() { _ = rows.Close() }()
+
+	if !rows.Next() {
+		return nil, ErrNotFound
+	}
+
+	var status ArticleStatus
+	var title string
+	var dateStr string
+	var modificationDateStr *string
+	var content string
+	var tag *string
+
+	err = rows.Scan(&status, &title, &dateStr, &modificationDateStr, &content, &tag)
+	if err != nil {
+		return nil, err
+	}
+
+	date, _ := time.Parse(time.DateOnly, dateStr)
+	var modificationDate *time.Time
+	if modificationDateStr != nil {
+		tmp, _ := time.Parse(time.DateOnly, *modificationDateStr)
+		modificationDate = &tmp
+	}
+
+	article := &Article{
+		ArticleProperties{
+			id,
+			title,
+			status,
+			make([]string, 0),
+			date,
+			modificationDate,
+		},
+		content,
+		nil,
+	}
+
+	if tag != nil {
+		article.Tags = append(article.Tags, *tag)
+	}
+
+	for rows.Next() {
+		err = rows.Scan(&status, &title, &dateStr, &modificationDateStr, &content, &tag)
+		if err != nil {
+			return nil, err
+		}
+
+		if tag != nil {
+			article.Tags = append(article.Tags, *tag)
+		}
+	}
+
+	return article, nil
+}
+
+func (db *Database) GetBlogArticleFile(showAll bool, articleId int64, fileId int64) (ArticleFile, error) {
+	filter := "WHERE blog_file.article_id = ? AND blog_file.id = ?"
+	if !showAll {
+		filter = filter + " AND blog_article.status = " + strconv.Itoa(ArticleStatusPublished)
+	}
+
+	statement := "SELECT blog_file.data FROM blog_file" +
+		" INNER JOIN blog_article ON blog_article.id = blog_file.article_id" +
+		" " + filter
+
+	var data []byte
+	err := db.db.QueryRow(statement, articleId, fileId).Scan(&data)
+	if err != nil {
+		if errors.Is(err, sql.ErrNoRows) {
+			return ArticleFile{}, ErrNotFound
+		}
+
+		return ArticleFile{}, err
+	}
+
+	return ArticleFile{
+		fileId,
+		data,
+	}, nil
+}
+
 func migrate(db *sql.DB, rootPassword string) error {
 	tx, err := db.Begin()
 	if err != nil {