Change structure of code tor frontend and backend one

cmd/backend/articles.go

@@ -0,0 +1,258 @@
+package backend
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"log"
+	"time"
+)
+
+type Article struct {
+	Title       string
+	Created     time.Time
+	Description string
+	Content     string
+	Published   bool
+	Rejected    bool
+	ID          int64
+	AuthorID    int64
+	IssueID     int64
+}
+
+func (db *DB) AddArticle(a *Article) (int64, error) {
+	var id int64
+	txOptions := &sql.TxOptions{Isolation: sql.LevelSerializable}
+	selectQuery := "SELECT id FROM issues WHERE published = false"
+	insertQuery := `
+    INSERT INTO articles
+        (title, description, content, published, rejected, author_id, issue_id)
+    VALUES (?, ?, ?, ?, ?, ?, ?)
+    `
+
+	for i := 0; i < TxMaxRetries; i++ {
+		id, err := func() (int64, error) {
+			tx, err := db.BeginTx(context.Background(), txOptions)
+			if err != nil {
+				return 0, fmt.Errorf("error starting transaction: %v", err)
+			}
+
+			if err = tx.QueryRow(selectQuery).Scan(&id); err != nil {
+				if rollbackErr := tx.Rollback(); rollbackErr != nil {
+					log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+				}
+				return 0, fmt.Errorf("error getting issue ID when adding article to DB: %v", err)
+			}
+
+			result, err := tx.Exec(insertQuery, a.Title, a.Description,
+				a.Content, a.Published, a.Rejected, a.AuthorID, id)
+			if err != nil {
+				if rollbackErr := tx.Rollback(); rollbackErr != nil {
+					log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+				}
+				return 0, fmt.Errorf("error inserting article into DB: %v", err)
+			}
+
+			id, err := result.LastInsertId()
+			if err != nil {
+				if rollbackErr := tx.Rollback(); rollbackErr != nil {
+					log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+				}
+				return 0, fmt.Errorf("error retrieving ID of added article: %v", err)
+			}
+
+			if err = tx.Commit(); err != nil {
+				return 0, fmt.Errorf("error committing transaction when adding article to DB: %v", err)
+			}
+			return id, nil
+		}()
+		if err == nil {
+			return id, nil
+		}
+
+		log.Println(err)
+		wait(i)
+	}
+
+	return 0, fmt.Errorf("error: %v unsuccessful retries for DB operation, aborting", TxMaxRetries)
+}
+
+func (db *DB) GetArticle(id int64) (*Article, error) {
+	query := `
+    SELECT title, created, description, content, published, author_id
+    FROM articles
+    WHERE id = ?
+    `
+	row := db.QueryRow(query, id)
+
+	article := new(Article)
+	var created []byte
+	var err error
+
+	if err := row.Scan(&article.Title, &created, &article.Description,
+		&article.Content, &article.Published, &article.AuthorID); err != nil {
+		return nil, fmt.Errorf("error scanning article row: %v", err)
+	}
+
+	article.ID = id
+	article.Created, err = time.Parse("2006-01-02 15:04:05", string(created))
+	if err != nil {
+		return nil, fmt.Errorf("error parsing created: %v", err)
+	}
+
+	return article, nil
+}
+
+func (db *DB) GetCertainArticles(published, rejected bool) ([]*Article, error) {
+	query := `
+    SELECT id, title, created, description, content, author_id, issue_id
+    FROM articles
+    WHERE published = ?
+    AND rejected = ?
+    `
+	rows, err := db.Query(query, published, rejected)
+	if err != nil {
+		return nil, fmt.Errorf("error querying articles: %v", err)
+	}
+
+	articleList := make([]*Article, 0)
+	for rows.Next() {
+		article := new(Article)
+		var created []byte
+
+		if err = rows.Scan(&article.ID, &article.Title, &created,
+			&article.Description, &article.Content, &article.AuthorID,
+			&article.IssueID); err != nil {
+			return nil, fmt.Errorf("error scanning article row: %v", err)
+		}
+
+		article.Published = false
+		article.Created, err = time.Parse("2006-01-02 15:04:05", string(created))
+		if err != nil {
+			return nil, fmt.Errorf("error parsing created: %v", err)
+		}
+
+		articleList = append(articleList, article)
+	}
+
+	return articleList, nil
+}
+
+func (db *DB) GetCurrentIssueArticles() ([]*Article, error) {
+	var issueID int64
+	txOptions := &sql.TxOptions{Isolation: sql.LevelSerializable}
+	issueQuery := "SELECT id FROM issues WHERE published = false"
+	articlesQuery := `
+    SELECT id, title, created, description, content, author_id
+    FROM articles
+    WHERE issue_id = ? AND published = true
+    `
+
+	for i := 0; i < TxMaxRetries; i++ {
+		id, err := func() ([]*Article, error) {
+			tx, err := db.BeginTx(context.Background(), txOptions)
+			if err != nil {
+				return nil, fmt.Errorf("error starting transaction: %v", err)
+			}
+
+			row := tx.QueryRow(issueQuery)
+			if err := row.Scan(&issueID); err != nil {
+				if rollbackErr := tx.Rollback(); rollbackErr != nil {
+					log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+				}
+				return nil, fmt.Errorf("error querying DB for unpublished issue: %v", err)
+			}
+
+			rows, err := tx.Query(articlesQuery, issueID)
+			if err != nil {
+				if rollbackErr := tx.Rollback(); rollbackErr != nil {
+					log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+				}
+				return nil, fmt.Errorf("error querying DB for articles of issue %v: %v", issueID, err)
+			}
+
+			articleList := make([]*Article, 0)
+			for rows.Next() {
+				article := new(Article)
+				var created []byte
+
+				if err = rows.Scan(&article.ID, &article.Title, &created,
+					&article.Description, &article.Content, &article.AuthorID); err != nil {
+					if rollbackErr := tx.Rollback(); rollbackErr != nil {
+						log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+					}
+					return nil, fmt.Errorf("error scanning article from issue %v: %v", issueID, err)
+				}
+
+				article.Created, err = time.Parse("2006-01-02 15:04:05", string(created))
+				if err != nil {
+					if rollbackErr := tx.Rollback(); rollbackErr != nil {
+						log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+					}
+					return nil, fmt.Errorf("error parsing created: %v", err)
+				}
+
+				articleList = append(articleList, article)
+			}
+
+			if err = tx.Commit(); err != nil {
+				return nil, fmt.Errorf("error committing transaction when getting articles of issue %v: %v", issueID, err)
+			}
+
+			return articleList, nil
+		}()
+		if err == nil {
+			return id, nil
+		}
+
+		log.Println(err)
+		wait(i)
+	}
+
+	return nil, fmt.Errorf("error: %v unsuccessful retries for DB operation, aborting", TxMaxRetries)
+}
+
+func (db *DB) AddArticleToCurrentIssue(id int64) error {
+	var issueID int64
+	txOptions := &sql.TxOptions{Isolation: sql.LevelSerializable}
+	selectQuery := "SELECT id FROM issues WHERE published = false"
+	updateQuery := "UPDATE articles SET issue_id = ? WHERE id = ?"
+
+	for i := 0; i < TxMaxRetries; i++ {
+		err := func() error {
+			tx, err := db.BeginTx(context.Background(), txOptions)
+			if err != nil {
+				return fmt.Errorf("error starting transaction: %v", err)
+			}
+
+			if err = tx.QueryRow(selectQuery).Scan(&issueID); err != nil {
+				if rollbackErr := tx.Rollback(); rollbackErr != nil {
+					log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+				}
+				return fmt.Errorf("error scanning row: %v", err)
+			}
+
+			_, err = db.Exec(updateQuery, issueID, id)
+			if err != nil {
+				if rollbackErr := tx.Rollback(); rollbackErr != nil {
+					log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+				}
+				return fmt.Errorf("error updating issueID for article: %v", err)
+			}
+
+			if err = tx.Commit(); err != nil {
+				return fmt.Errorf("error committing transaction when getting articles of issue %v: %v", issueID, err)
+			}
+
+			return nil
+		}()
+		if err == nil {
+			return nil
+		}
+
+		log.Println(err)
+		wait(i)
+	}
+
+	return fmt.Errorf("error: %v unsuccessful retries for DB operation, aborting", TxMaxRetries)
+}

cmd/backend/articles_tags.go

@@ -0,0 +1,107 @@
+package backend
+
+import (
+	"fmt"
+	"log"
+)
+
+func (db *DB) WriteArticleTags(articleID int64, tagIDs []int64) error {
+	query := "INSERT INTO articles_tags (article_id, tag_id) VALUES (?, ?)"
+
+	for i := 0; i < TxMaxRetries; i++ {
+		err := func() error {
+			tx, err := db.Begin()
+			if err != nil {
+				return fmt.Errorf("error starting transaction: %v", err)
+			}
+
+			for _, tagID := range tagIDs {
+				if _, err := tx.Exec(query, articleID, tagID); err != nil {
+					if rollbackErr := tx.Rollback(); rollbackErr != nil {
+						log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+					}
+					return fmt.Errorf("error inserting into articles_tags: %v", err)
+				}
+			}
+
+			if err = tx.Commit(); err != nil {
+				return fmt.Errorf("error committing transaction: %v", err)
+			}
+			return nil
+		}()
+		if err == nil {
+			return nil
+		}
+
+		log.Println(err)
+		wait(i)
+	}
+	return fmt.Errorf("error: %v unsuccessful retries for DB operation, aborting", TxMaxRetries)
+}
+
+func (db *DB) GetArticleTags(articleID int64) ([]*Tag, error) {
+	query := `
+    SELECT t.id, t.name
+    FROM articles a
+    INNER JOIN articles_tags at ON a.id = at.article_id
+    INNER JOIN tags t ON at.tag_id = t.id
+    WHERE a.id = ?
+    `
+	rows, err := db.Query(query, articleID)
+	if err != nil {
+		return nil, fmt.Errorf("error querying articles_tags: %v", err)
+	}
+
+	tags := make([]*Tag, 0)
+	for rows.Next() {
+		tag := new(Tag)
+		if err = rows.Scan(&tag.ID, &tag.Name); err != nil {
+			return nil, fmt.Errorf("error scanning rows: %v", err)
+		}
+		tags = append(tags, tag)
+	}
+
+	return tags, nil
+}
+
+func (db *DB) UpdateArticleTags(articleID int64, tagIDs []int64) error {
+	deleteQuery := "DELETE FROM articles_tags WHERE article_id = ?"
+	insertQuery := "INSERT INTO articles_tags (article_id, tag_id) VALUES (?, ?)"
+
+	for i := 0; i < TxMaxRetries; i++ {
+		err := func() error {
+			tx, err := db.Begin()
+			if err != nil {
+				return fmt.Errorf("error starting transaction: %v", err)
+			}
+
+			if _, err := tx.Exec(deleteQuery, articleID); err != nil {
+				if rollbackErr := tx.Rollback(); rollbackErr != nil {
+					log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+				}
+				return fmt.Errorf("error deleting entries from articles_tags before inserting new ones: %v", err)
+			}
+
+			for _, tagID := range tagIDs {
+				if _, err := tx.Exec(insertQuery, articleID, tagID); err != nil {
+					if rollbackErr := tx.Rollback(); rollbackErr != nil {
+						log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+					}
+					return fmt.Errorf("error inserting new entries into articles_tags: %v", err)
+				}
+			}
+
+			if err = tx.Commit(); err != nil {
+				return fmt.Errorf("error committing transaction: %v", err)
+			}
+			return nil
+		}()
+		if err == nil {
+			return nil
+		}
+
+		log.Println(err)
+		wait(i)
+	}
+	return fmt.Errorf("error: %v unsuccessful retries for DB operation, aborting", TxMaxRetries)
+}

cmd/backend/config.go

@@ -0,0 +1,131 @@
+package backend
+
+import (
+	"flag"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/BurntSushi/toml"
+)
+
+type Config struct {
+	DBName      string
+	Description string
+	Domain      string
+	KeyFile     string
+	Link        string
+	LogFile     string
+	PicsDir     string
+	Port        string
+	RSSFile     string
+	Title       string
+	WebDir      string
+}
+
+func newConfig() *Config {
+	return &Config{
+		DBName:  "cpolis",
+		KeyFile: "/var/www/cpolis/cpolis.key",
+		LogFile: "/var/log/cpolis.log",
+		PicsDir: "/var/www/cpolis/pics",
+		RSSFile: "/var/www/cpolis/cpolis.rss",
+		WebDir:  "/var/www/cpolis/web",
+	}
+}
+
+func (c *Config) readFile() error {
+	cfgFile, err := filepath.Abs(os.Getenv("HOME") + "/.config/cpolis/config.toml")
+	if err != nil {
+		return fmt.Errorf("error getting absolute path for config file: %v", err)
+	}
+
+	_, err = os.Stat(cfgFile)
+	if os.IsNotExist(err) {
+		fileStrings := strings.Split(cfgFile, "/")
+
+		dir := strings.Join(fileStrings[0:len(fileStrings)-1], "/")
+		if err = os.MkdirAll(dir, 0755); err != nil {
+			return fmt.Errorf("error creating config directory: %v", err)
+		}
+
+		fileName := fileStrings[len(fileStrings)-1]
+		file, err := os.Create(dir + "/" + fileName)
+		if err != nil {
+			return fmt.Errorf("error creating config file: %v", err)
+		}
+		defer file.Close()
+		if err = file.Chmod(0644); err != nil {
+			return fmt.Errorf("error setting permissions for config file: %v", err)
+		}
+	} else {
+		_, err = toml.DecodeFile(cfgFile, c)
+		if err != nil {
+			return fmt.Errorf("error reading config file: %v", err)
+		}
+	}
+
+	return nil
+}
+
+func (c *Config) handleCliArgs() error {
+	var err error
+	port := 8080
+
+	flag.StringVar(&c.DBName, "db", c.DBName, "DB name")
+	flag.StringVar(&c.Description, "desc", c.Description, "Channel description")
+	flag.StringVar(&c.Domain, "domain", c.Domain, "domain name")
+	flag.StringVar(&c.KeyFile, "key", c.KeyFile, "key file")
+	flag.StringVar(&c.Link, "link", c.Link, "Channel Link")
+	flag.StringVar(&c.LogFile, "log", c.LogFile, "log file")
+	flag.StringVar(&c.PicsDir, "pics", c.PicsDir, "pictures directory")
+	flag.StringVar(&c.RSSFile, "rss", c.RSSFile, "RSS file")
+	flag.StringVar(&c.Title, "title", c.Title, "Channel title")
+	flag.StringVar(&c.WebDir, "web", c.WebDir, "web directory")
+	flag.IntVar(&port, "port", port, "port")
+	flag.Parse()
+
+	c.KeyFile, err = filepath.Abs(c.KeyFile)
+	if err != nil {
+		return fmt.Errorf("error finding absolute path for key file: %v", err)
+	}
+
+	c.LogFile, err = filepath.Abs(c.LogFile)
+	if err != nil {
+		return fmt.Errorf("error finding absolute path for log file: %v", err)
+	}
+
+	c.PicsDir, err = filepath.Abs(c.PicsDir)
+	if err != nil {
+		return fmt.Errorf("error finding absolute path for pics dir: %v", err)
+	}
+
+	c.Port = fmt.Sprint(":", port)
+
+	c.RSSFile, err = filepath.Abs(c.RSSFile)
+	if err != nil {
+		return fmt.Errorf("error finding absolute path for RSS file: %v", err)
+	}
+
+	c.WebDir, err = filepath.Abs(c.WebDir)
+	if err != nil {
+		return fmt.Errorf("error finding absolute path for web dir: %v", err)
+	}
+
+	return nil
+}
+
+func HandleConfig() (*Config, error) {
+	config := newConfig()
+
+	if err := config.readFile(); err != nil {
+		return nil, fmt.Errorf("error reading config file: %v", err)
+	}
+
+	if err := config.handleCliArgs(); err != nil {
+		return nil, fmt.Errorf("error handling cli arguments: %v", err)
+	}
+
+	return config, nil
+}

cmd/backend/db.go

@@ -0,0 +1,167 @@
+package backend
+
+import (
+	"bufio"
+	"database/sql"
+	"fmt"
+	"log"
+	"math"
+	"math/rand/v2"
+	"os"
+	"strings"
+	"syscall"
+	"time"
+
+	"github.com/go-sql-driver/mysql"
+	"golang.org/x/term"
+)
+
+var TxMaxRetries = 5
+
+type (
+	DB struct{ *sql.DB }
+	Tx struct{ *sql.Tx }
+
+	Attribute struct {
+		Value   any
+		Table   string
+		AttName string
+		ID      int64
+	}
+)
+
+func getUsername() (string, error) {
+	user := os.Getenv("DB_USER")
+	if user == "" {
+		var err error
+		fmt.Printf("DB Benutzer: ")
+		user, err = bufio.NewReader(os.Stdin).ReadString('\n')
+		if err != nil {
+			return "", fmt.Errorf("error reading username: %v", err)
+		}
+	}
+	return strings.TrimSpace(user), nil
+}
+
+func getPassword() (string, error) {
+	pass := os.Getenv("DB_PASS")
+	if pass == "" {
+		fmt.Printf("DB Passwort: ")
+		bytePass, err := term.ReadPassword(int(syscall.Stdin))
+		if err != nil {
+			return "", fmt.Errorf("error reading password: %v", err)
+		}
+		fmt.Println()
+		pass = strings.TrimSpace(string(bytePass))
+	}
+	return pass, nil
+}
+
+func getCredentials() (string, string, error) {
+	user, err := getUsername()
+	if err != nil {
+		return "", "", fmt.Errorf("error getting username: %v", err)
+	}
+
+	pass, err := getPassword()
+	if err != nil {
+		return "", "", fmt.Errorf("error getting password: %v", err)
+	}
+
+	return user, pass, nil
+}
+
+func wait(iteration int) {
+	waitTime := time.Duration(math.Pow(2, float64(iteration))) * 100 * time.Millisecond
+	jitter := time.Duration(rand.IntN(int(waitTime)/2)) * time.Millisecond
+	time.Sleep(waitTime + jitter)
+}
+
+func OpenDB(dbName string) (*DB, error) {
+	var err error
+	db := DB{DB: new(sql.DB)}
+
+	cfg := mysql.NewConfig()
+	cfg.DBName = dbName
+	cfg.User, cfg.Passwd, err = getCredentials()
+	if err != nil {
+		return nil, fmt.Errorf("error reading user credentials for DB: %v", err)
+	}
+
+	db.DB, err = sql.Open("mysql", cfg.FormatDSN())
+	if err != nil {
+		return nil, fmt.Errorf("error opening DB: %v", err)
+	}
+	if err = db.Ping(); err != nil {
+		return nil, fmt.Errorf("error pinging DB: %v", err)
+	}
+
+	return &db, nil
+}
+
+func (db *DB) UpdateAttributes(a ...*Attribute) error {
+	for i := 0; i < TxMaxRetries; i++ {
+		err := func() error {
+			tx, err := db.Begin()
+			if err != nil {
+				return fmt.Errorf("error starting transaction: %v", err)
+			}
+
+			for _, attribute := range a {
+				query := fmt.Sprintf(`
+                    UPDATE %s
+                    SET %s = ?
+                    WHERE id = ?
+                    `, attribute.Table, attribute.AttName)
+				if _, err := tx.Exec(query, attribute.Value, attribute.ID); err != nil {
+					if rollbackErr := tx.Rollback(); rollbackErr != nil {
+						log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+					}
+					return fmt.Errorf("error updating %v in DB: %v", attribute.AttName, err)
+				}
+			}
+
+			if err = tx.Commit(); err != nil {
+				return fmt.Errorf("error committing transaction: %v", err)
+			}
+			return nil
+		}()
+		if err == nil {
+			return nil
+		}
+
+		log.Println(err)
+		wait(i)
+	}
+	return fmt.Errorf("error: %v unsuccessful retries for DB operation, aborting", TxMaxRetries)
+}
+
+func (db *DB) CountEntries(table string) (int64, error) {
+	var count int64
+
+	query := fmt.Sprintf("SELECT COUNT(*) FROM %s", table)
+	row := db.QueryRow(query)
+	if err := row.Scan(&count); err != nil {
+		return 0, fmt.Errorf("error counting rows in user DB: %v", err)
+	}
+
+	return count, nil
+}
+
+func (tx *Tx) UpdateAttributes(a ...*Attribute) error {
+	for _, attribute := range a {
+		query := fmt.Sprintf(`
+            UPDATE %s
+            SET %s = ?
+            WHERE id = ?
+            `, attribute.Table, attribute.AttName)
+		if _, err := tx.Exec(query, attribute.Value, attribute.ID); err != nil {
+			if rollbackErr := tx.Rollback(); rollbackErr != nil {
+				log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+			}
+			return fmt.Errorf("error updating %v in DB: %v", attribute.AttName, err)
+		}
+	}
+
+	return nil
+}

cmd/backend/issues.go

@@ -0,0 +1,65 @@
+package backend
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"log"
+)
+
+func (db *DB) AddIssue() (int64, error) {
+	query := "INSERT INTO issues (published) VALUES (?)"
+	result, err := db.Exec(query, false)
+	if err != nil {
+		return 0, fmt.Errorf("error inserting issue into DB: %v", err)
+	}
+
+	id, err := result.LastInsertId()
+	if err != nil {
+		return 0, fmt.Errorf("error getting ID of added issue: %v", err)
+	}
+
+	return id, nil
+}
+
+func (db *DB) PublishLatestIssue() error {
+	txOptions := &sql.TxOptions{Isolation: sql.LevelSerializable}
+	updateQuery := "UPDATE issues SET published = true WHERE published = false"
+	insertQuery := "INSERT INTO issues (published) VALUES (?)"
+
+	for i := 0; i < TxMaxRetries; i++ {
+		err := func() error {
+			tx, err := db.BeginTx(context.Background(), txOptions)
+			if err != nil {
+				return fmt.Errorf("error starting transaction: %v", err)
+			}
+
+			if _, err := tx.Exec(updateQuery); err != nil {
+				if rollbackErr := tx.Rollback(); rollbackErr != nil {
+					log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+				}
+				return fmt.Errorf("error publishing issue: %v", err)
+			}
+
+			if _, err := tx.Exec(insertQuery, false); err != nil {
+				if rollbackErr := tx.Rollback(); rollbackErr != nil {
+					log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+				}
+				return fmt.Errorf("error inserting new issue into DB: %v", err)
+			}
+
+			if err = tx.Commit(); err != nil {
+				return fmt.Errorf("error committing transaction when publishing issue: %v", err)
+			}
+			return nil
+		}()
+		if err == nil {
+			return nil
+		}
+
+		log.Println(err)
+		wait(i)
+	}
+
+	return fmt.Errorf("error: %v unsuccessful retries for DB operation, aborting", TxMaxRetries)
+}

cmd/backend/markdown.go

@@ -0,0 +1,35 @@
+package backend
+
+import (
+	"bytes"
+	"fmt"
+
+	"github.com/microcosm-cc/bluemonday"
+	"github.com/yuin/goldmark"
+)
+
+func ConvertToHTML(md string) (string, error) {
+	var buf bytes.Buffer
+
+	if err := goldmark.Convert([]byte(md), &buf); err != nil {
+		return "", fmt.Errorf("error converting markdown to html: %v", err)
+	}
+
+	p := bluemonday.UGCPolicy()
+	html := p.Sanitize(buf.String())
+
+	return html, nil
+}
+
+func ConvertToPlain(md string) (string, error) {
+	var buf bytes.Buffer
+
+	if err := goldmark.Convert([]byte(md), &buf); err != nil {
+		return "", fmt.Errorf("error converting markdown to html: %v", err)
+	}
+
+	p := bluemonday.StrictPolicy()
+	plain := p.Sanitize(buf.String())
+
+	return plain, nil
+}

cmd/backend/rss.go

@@ -0,0 +1,132 @@
+package backend
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"time"
+
+	"git.streifling.com/jason/rss"
+)
+
+func GetChannel(db *DB, title, link, description string) (*rss.Channel, error) {
+	channel := &rss.Channel{
+		Title:       title,
+		Link:        link,
+		Description: description,
+		Items:       make([]*rss.Item, 0),
+	}
+
+	articles, err := db.GetCertainArticles(true, false)
+	if err != nil {
+		return nil, fmt.Errorf("error fetching published articles: %v", err)
+	}
+
+	for _, article := range articles {
+		tags, err := db.GetArticleTags(article.ID)
+		if err != nil {
+			return nil, fmt.Errorf("error fetching tags for article %v: %v", article.Title, err)
+		}
+		tagNames := make([]string, 0)
+		for _, tag := range tags {
+			tagNames = append(tagNames, tag.Name)
+		}
+
+		user, err := db.GetUser(article.AuthorID)
+		if err != nil {
+			return nil, fmt.Errorf("error finding user %v: %v", article.AuthorID, err)
+		}
+
+		channel.Items = append(channel.Items, &rss.Item{
+			Title:       article.Title,
+			Author:      user.FirstName + user.LastName,
+			PubDate:     article.Created.Format(time.RFC1123Z),
+			Description: article.Description,
+			Content:     &rss.Content{Value: article.Content},
+			Categories:  tagNames,
+		})
+	}
+
+	return channel, nil
+}
+
+func GenerateRSS(db *DB, title, link, desc string) (*string, error) {
+	channel := &rss.Channel{
+		Title:       title,
+		Link:        link,
+		Description: desc,
+		Items:       make([]*rss.Item, 0),
+	}
+
+	articles, err := db.GetCertainArticles(true, false)
+	if err != nil {
+		return nil, fmt.Errorf("error getting published articles for RSS feed: %v", err)
+	}
+
+	for _, article := range articles {
+		tags, err := db.GetArticleTags(article.ID)
+		if err != nil {
+			return nil, fmt.Errorf("error getting tags for articles for RSS feed: %v", err)
+		}
+		tagNames := make([]string, 0)
+		for _, tag := range tags {
+			tagNames = append(tagNames, tag.Name)
+		}
+		tagNames = append(tagNames, fmt.Sprint("Orient Express ", article.IssueID))
+
+		user, err := db.GetUser(article.AuthorID)
+		if err != nil {
+			return nil, fmt.Errorf("error getting user user info for RSS feed: %v", err)
+		}
+
+		articleTitle, err := ConvertToPlain(article.Title)
+		if err != nil {
+			return nil, fmt.Errorf("error converting title to plain text for RSS feed: %v", err)
+		}
+
+		articleDescription, err := ConvertToPlain(article.Description)
+		if err != nil {
+			return nil, fmt.Errorf("error converting description to plain text for RSS feed: %v", err)
+		}
+
+		articleContent, err := ConvertToHTML(article.Content)
+		if err != nil {
+			return nil, fmt.Errorf("error converting content to HTML for RSS feed: %v", err)
+		}
+
+		channel.Items = append(channel.Items, &rss.Item{
+			Title:       articleTitle,
+			Author:      user.FirstName + " " + user.LastName,
+			PubDate:     article.Created.Format(time.RFC1123Z),
+			Description: articleDescription,
+			Content:     &rss.Content{Value: articleContent},
+			Categories:  tagNames,
+		})
+	}
+
+	feed := rss.NewFeed()
+	feed.Channels = append(feed.Channels, channel)
+	rss, err := feed.ToXML("UTF-8")
+	if err != nil {
+		return nil, fmt.Errorf("error converting RSS feed to XML: %v", err)
+	}
+
+	return &rss, nil
+}
+
+func SaveRSS(filename string, feed *string) error {
+	file, err := os.Create(filename)
+	if err != nil {
+		return fmt.Errorf("error creating file for RSS feed: %v", err)
+	}
+	defer file.Close()
+	if err = file.Chmod(0644); err != nil {
+		return fmt.Errorf("error setting permissions for RSS file: %v", err)
+	}
+
+	if _, err = io.WriteString(file, *feed); err != nil {
+		return fmt.Errorf("error writing to RSS file: %v", err)
+	}
+
+	return nil
+}

cmd/backend/sessions.go

@@ -0,0 +1,61 @@
+package backend
+
+import (
+	"crypto/rand"
+	"encoding/gob"
+	"fmt"
+	"io"
+	"os"
+
+	"github.com/gorilla/sessions"
+)
+
+type CookieStore struct {
+	sessions.CookieStore
+}
+
+func NewKey() ([]byte, error) {
+	key := make([]byte, 32)
+
+	if _, err := io.ReadFull(rand.Reader, key); err != nil {
+		return nil, fmt.Errorf("error generating key: %v", err)
+	}
+
+	return key, nil
+}
+
+func SaveKey(key []byte, filename string) error {
+	file, err := os.Create(filename)
+	if err != nil {
+		return fmt.Errorf("error creating key file: %v", err)
+	}
+	defer file.Close()
+	file.Chmod(0600)
+
+	if err = gob.NewEncoder(file).Encode(key); err != nil {
+		return fmt.Errorf("error ecoding key: %v", err)
+	}
+
+	return nil
+}
+
+func LoadKey(filename string) ([]byte, error) {
+	file, err := os.Open(filename)
+	if err != nil {
+		return nil, fmt.Errorf("error opening key file: %v", err)
+	}
+
+	key := make([]byte, 32)
+	if err = gob.NewDecoder(file).Decode(&key); err != nil {
+		return nil, fmt.Errorf("error decoding key: %v", err)
+	}
+
+	return key, nil
+}
+
+func NewCookieStore(key []byte) *CookieStore {
+	store := sessions.NewCookieStore(key)
+	store.Options.Secure = true
+	store.Options.HttpOnly = true
+	return &CookieStore{*store}
+}

cmd/backend/tags.go

@@ -0,0 +1,35 @@
+package backend
+
+import "fmt"
+
+type Tag struct {
+	Name string
+	ID   int64
+}
+
+func (db *DB) AddTag(tagName string) error {
+	query := "INSERT INTO tags (name) VALUES (?)"
+	if _, err := db.Exec(query, tagName); err != nil {
+		return fmt.Errorf("error inserting tag into DB: %v", err)
+	}
+	return nil
+}
+
+func (db *DB) GetTagList() ([]*Tag, error) {
+	query := "SELECT id, name FROM tags"
+	rows, err := db.Query(query)
+	if err != nil {
+		return nil, fmt.Errorf("error querying tags: %v", err)
+	}
+
+	tagList := make([]*Tag, 0)
+	for rows.Next() {
+		tag := new(Tag)
+		if err = rows.Scan(&tag.ID, &tag.Name); err != nil {
+			return nil, fmt.Errorf("error scanning tag row: %v", err)
+		}
+		tagList = append(tagList, tag)
+	}
+
+	return tagList, nil
+}

cmd/backend/users.go

@@ -0,0 +1,380 @@
+package backend
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"log"
+
+	"golang.org/x/crypto/bcrypt"
+)
+
+const (
+	Admin = iota
+	Publisher
+	Editor
+	Author
+	NonExistent
+)
+
+type User struct {
+	UserName  string
+	FirstName string
+	LastName  string
+	ID        int64
+	Role      int
+}
+
+func (db *DB) AddUser(u *User, pass string) (int64, error) {
+	hashedPass, err := bcrypt.GenerateFromPassword([]byte(pass), bcrypt.DefaultCost)
+	if err != nil {
+		return 0, fmt.Errorf("error creating password hash: %v", err)
+	}
+
+	query := `
+    INSERT INTO users (username, password, first_name, last_name, role)
+    VALUES (?, ?, ?, ?, ?)
+    `
+	result, err := db.Exec(query, u.UserName, string(hashedPass), u.FirstName, u.LastName, u.Role)
+	if err != nil {
+		return 0, fmt.Errorf("error inserting new user %v into DB: %v", u.UserName, err)
+	}
+	id, err := result.LastInsertId()
+	if err != nil {
+		return 0, fmt.Errorf("error inserting user into DB: %v", err)
+	}
+
+	return id, nil
+}
+
+func (db *DB) GetID(userName string) (int64, bool) {
+	var id int64
+
+	query := `
+    SELECT id
+    FROM users
+    WHERE username = ?
+    `
+	row := db.QueryRow(query, userName)
+	if err := row.Scan(&id); err != nil {
+		return 0, false
+	}
+
+	return id, true
+}
+
+func (db *DB) CheckPassword(id int64, pass string) error {
+	var queriedPass string
+
+	query := `
+    SELECT password
+    FROM users
+    WHERE id = ?
+    `
+	row := db.QueryRow(query, id)
+	if err := row.Scan(&queriedPass); err != nil {
+		return fmt.Errorf("error reading password from DB: %v", err)
+	}
+
+	if err := bcrypt.CompareHashAndPassword([]byte(queriedPass), []byte(pass)); err != nil {
+		return fmt.Errorf("incorrect password: %v", err)
+	}
+
+	return nil
+}
+
+func (tx *Tx) ChangePassword(id int64, oldPass, newPass string) error {
+	var queriedPass string
+	getQuery := `
+    SELECT password
+    FROM users
+    WHERE id = ?
+    `
+	row := tx.QueryRow(getQuery, id)
+	if err := row.Scan(&queriedPass); err != nil {
+		if rollbackErr := tx.Rollback(); rollbackErr != nil {
+			log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+		}
+		return fmt.Errorf("error reading password from DB: %v", err)
+	}
+
+	if err := bcrypt.CompareHashAndPassword([]byte(queriedPass), []byte(oldPass)); err != nil {
+		if rollbackErr := tx.Rollback(); rollbackErr != nil {
+			log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+		}
+		return fmt.Errorf("incorrect password: %v", err)
+	}
+
+	newHashedPass, err := bcrypt.GenerateFromPassword([]byte(newPass), bcrypt.DefaultCost)
+	if err != nil {
+		if rollbackErr := tx.Rollback(); rollbackErr != nil {
+			log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+		}
+		return fmt.Errorf("error creating password hash: %v", err)
+	}
+
+	setQuery := `
+    UPDATE users
+    SET password = ?
+    WHERE id = ?
+    `
+	if _, err = tx.Exec(setQuery, string(newHashedPass), id); err != nil {
+		if rollbackErr := tx.Rollback(); rollbackErr != nil {
+			log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+		}
+		return fmt.Errorf("error updating password in DB: %v", err)
+	}
+
+	return nil
+}
+
+// TODO: No need for ID field in general
+func (db *DB) GetUser(id int64) (*User, error) {
+	user := new(User)
+	query := `
+    SELECT id, username, first_name, last_name, role
+    FROM users
+    WHERE id = ?
+    `
+
+	row := db.QueryRow(query, id)
+	if err := row.Scan(&user.ID, &user.UserName, &user.FirstName,
+		&user.LastName, &user.Role); err != nil {
+		return nil, fmt.Errorf("error reading user information: %v", err)
+	}
+
+	return user, nil
+}
+
+func (db *DB) UpdateOwnAttributes(id int64, user, first, last, oldPass, newPass, newPass2 string) error {
+	passwordEmpty := true
+	if len(newPass) > 0 || len(newPass2) > 0 {
+		if newPass != newPass2 {
+			return fmt.Errorf("error: passwords do not match")
+		}
+		passwordEmpty = false
+	}
+
+	tx := new(Tx)
+	var err error
+
+	for i := 0; i < TxMaxRetries; i++ {
+		err := func() error {
+			tx.Tx, err = db.Begin()
+			if err != nil {
+				return fmt.Errorf("error starting transaction: %v", err)
+			}
+
+			if !passwordEmpty {
+				if err = tx.ChangePassword(id, oldPass, newPass); err != nil {
+					if rollbackErr := tx.Rollback(); rollbackErr != nil {
+						log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+					}
+					return fmt.Errorf("error changing password: %v", err)
+				}
+			}
+
+			if err = tx.UpdateAttributes(
+				&Attribute{Table: "users", ID: id, AttName: "username", Value: user},
+				&Attribute{Table: "users", ID: id, AttName: "first_name", Value: first},
+				&Attribute{Table: "users", ID: id, AttName: "last_name", Value: last},
+			); err != nil {
+				if rollbackErr := tx.Rollback(); rollbackErr != nil {
+					log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+				}
+				return fmt.Errorf("error updating attributes in DB: %v", err)
+			}
+
+			if err = tx.Commit(); err != nil {
+				return fmt.Errorf("error committing transaction: %v", err)
+			}
+
+			return nil
+		}()
+		if err == nil {
+			return nil
+		}
+
+		log.Println(err)
+		wait(i)
+	}
+
+	return fmt.Errorf("error: %v unsuccessful retries for DB operation, aborting", TxMaxRetries)
+}
+
+func (db *DB) AddFirstUser(u *User, pass string) (int64, error) {
+	var numUsers int64
+	txOptions := &sql.TxOptions{Isolation: sql.LevelSerializable}
+	selectQuery := "SELECT COUNT(*) FROM users"
+	insertQuery := `
+    INSERT INTO users (username, password, first_name, last_name, role)
+    VALUES (?, ?, ?, ?, ?)
+    `
+
+	for i := 0; i < TxMaxRetries; i++ {
+		id, err := func() (int64, error) {
+			tx, err := db.BeginTx(context.Background(), txOptions)
+			if err != nil {
+				return 0, fmt.Errorf("error starting transaction: %v", err)
+			}
+
+			if err := tx.QueryRow(selectQuery).Scan(&numUsers); err != nil {
+				if rollbackErr := tx.Rollback(); rollbackErr != nil {
+					log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+				}
+				return 0, fmt.Errorf("error getting ID of %v: %v", u.UserName, err)
+			}
+			if numUsers != 0 {
+				if err = tx.Commit(); err != nil {
+					return 0, fmt.Errorf("error committing transaction: %v", err)
+				}
+				return 2, nil
+			}
+
+			hashedPass, err := bcrypt.GenerateFromPassword([]byte(pass), bcrypt.DefaultCost)
+			if err != nil {
+				if rollbackErr := tx.Rollback(); rollbackErr != nil {
+					log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+				}
+				return 0, fmt.Errorf("error creating password hash: %v", err)
+			}
+
+			result, err := tx.Exec(insertQuery, u.UserName, string(hashedPass), u.FirstName, u.LastName, u.Role)
+			if err != nil {
+				if rollbackErr := tx.Rollback(); rollbackErr != nil {
+					log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+				}
+				return 0, fmt.Errorf("error inserting new user %v into DB: %v", u.UserName, err)
+			}
+
+			id, err := result.LastInsertId()
+			if err != nil {
+				if rollbackErr := tx.Rollback(); rollbackErr != nil {
+					log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+				}
+				return 0, fmt.Errorf("error inserting user into DB: %v", err)
+			}
+
+			if err = tx.Commit(); err != nil {
+				return 0, fmt.Errorf("error committing transaction: %v", err)
+			}
+			return id, nil
+		}()
+		if err == nil {
+			return id, nil
+		}
+
+		log.Println(err)
+		wait(i)
+	}
+	return 0, fmt.Errorf("error: %v unsuccessful retries for DB operation, aborting", TxMaxRetries)
+}
+
+func (db *DB) GetAllUsers() (map[int64]*User, error) {
+	query := "SELECT id, username, first_name, last_name, role FROM users"
+
+	rows, err := db.Query(query)
+	if err != nil {
+		return nil, fmt.Errorf("error getting all users from DB: %v", err)
+	}
+
+	users := make(map[int64]*User, 0)
+	for rows.Next() {
+		user := new(User)
+		if err = rows.Scan(&user.ID, &user.UserName, &user.FirstName,
+			&user.LastName, &user.Role); err != nil {
+			return nil, fmt.Errorf("error getting user info: %v", err)
+		}
+		users[user.ID] = user
+	}
+
+	return users, nil
+}
+
+func (tx *Tx) SetPassword(id int64, newPass string) error {
+	hashedPass, err := bcrypt.GenerateFromPassword([]byte(newPass), bcrypt.DefaultCost)
+	if err != nil {
+		if rollbackErr := tx.Rollback(); rollbackErr != nil {
+			log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+		}
+		return fmt.Errorf("error creating password hash: %v", err)
+	}
+
+	setQuery := "UPDATE users SET password = ? WHERE id = ?"
+	if _, err = tx.Exec(setQuery, string(hashedPass), id); err != nil {
+		if rollbackErr := tx.Rollback(); rollbackErr != nil {
+			log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+		}
+		return fmt.Errorf("error updating password in DB: %v", err)
+	}
+
+	return nil
+}
+
+func (db *DB) UpdateUserAttributes(id int64, user, first, last, newPass, newPass2 string, role int) error {
+	passwordEmpty := true
+	if len(newPass) > 0 || len(newPass2) > 0 {
+		if newPass != newPass2 {
+			return fmt.Errorf("error: passwords do not match")
+		}
+		passwordEmpty = false
+	}
+
+	tx := new(Tx)
+	var err error
+
+	for i := 0; i < TxMaxRetries; i++ {
+		err := func() error {
+			tx.Tx, err = db.Begin()
+			if err != nil {
+				return fmt.Errorf("error starting transaction: %v", err)
+			}
+
+			if !passwordEmpty {
+				if err = tx.SetPassword(id, newPass); err != nil {
+					if rollbackErr := tx.Rollback(); rollbackErr != nil {
+						log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+					}
+					return fmt.Errorf("error changing password: %v", err)
+				}
+			}
+
+			if err = tx.UpdateAttributes(
+				&Attribute{Table: "users", ID: id, AttName: "username", Value: user},
+				&Attribute{Table: "users", ID: id, AttName: "first_name", Value: first},
+				&Attribute{Table: "users", ID: id, AttName: "last_name", Value: last},
+				&Attribute{Table: "users", ID: id, AttName: "role", Value: role},
+			); err != nil {
+				if rollbackErr := tx.Rollback(); rollbackErr != nil {
+					log.Fatalf("transaction error: %v, rollback error: %v", err, rollbackErr)
+				}
+				return fmt.Errorf("error updating attributes in DB: %v", err)
+			}
+
+			if err = tx.Commit(); err != nil {
+				return fmt.Errorf("error committing transaction: %v", err)
+			}
+
+			return nil
+		}()
+		if err == nil {
+			return nil
+		}
+
+		log.Println(err)
+		wait(i)
+	}
+
+	return fmt.Errorf("error: %v unsuccessful retries for DB operation, aborting", TxMaxRetries)
+}
+
+func (db *DB) DeleteUser(id int64) error {
+	query := "DELETE FROM users WHERE id = ?"
+
+	_, err := db.Exec(query, id)
+	if err != nil {
+		return fmt.Errorf("error deleting user %v from DB: %v", id, err)
+	}
+
+	return nil
+}