Split up main.go into multiple files.

Added Db support to save last viewed Manga and chapter, and auto load it next time you start the server.
Added Providers to add more Manga Platforms than just Bato in the future

database.go

@@ -0,0 +1,165 @@
+package main
+
+import (
+	"database/sql"
+	_ "embed"
+
+	_ "github.com/mattn/go-sqlite3"
+)
+
+type Manga struct {
+	Id            int
+	Title         string
+	TimeStampUnix int64
+
+	// Not in DB
+	LatestChapter *Chapter
+}
+
+type Chapter struct {
+	Id            int
+	Manga         *Manga
+	Url           string
+	Name          string
+	Number        int
+	TimeStampUnix int64
+}
+
+type DatabaseManager struct {
+	ConnectionString string
+	db               *sql.DB
+	Mangas           map[int]*Manga
+	Chapters         map[int]*Chapter
+
+	CreateIfNotExists bool
+}
+
+func NewDatabase(connectionString string, createIfNotExists bool) DatabaseManager {
+	return DatabaseManager{
+		ConnectionString: connectionString,
+
+		Mangas:            make(map[int]*Manga),
+		Chapters:          make(map[int]*Chapter),
+		CreateIfNotExists: createIfNotExists,
+	}
+}
+
+func (dbMgr *DatabaseManager) Open() error {
+	db, err := sql.Open("sqlite3", dbMgr.ConnectionString)
+	if err != nil {
+		return err
+	}
+	dbMgr.db = db
+	if dbMgr.CreateIfNotExists {
+		err = dbMgr.createDatabaseIfNotExists()
+		if err != nil {
+			return err
+		}
+	}
+	err = dbMgr.load()
+	return err
+}
+
+func (dbMgr *DatabaseManager) Close() error {
+	err := dbMgr.db.Close()
+	if err != nil {
+		return err
+	}
+
+	dbMgr.Mangas = nil
+	dbMgr.Chapters = nil
+	dbMgr.db = nil
+	return nil
+}
+
+func (dbMgr *DatabaseManager) Save() error {
+	db := dbMgr.db
+
+	for _, m := range dbMgr.Mangas {
+		count := 0
+		err := db.QueryRow("SELECT COUNT(*) FROM Manga where ID = ?", m.Id).Scan(&count)
+		if err != nil {
+			return err
+		}
+
+		if count == 0 {
+			_, err := db.Exec("INSERT INTO Manga(ID, Title, TimeStampUnixEpoch) values(?, ?, ?)", m.Id, m.Title, m.TimeStampUnix)
+			if err != nil {
+				return err
+			}
+		} else {
+			_, err := db.Exec("UPDATE Manga set Title = ?, TimeStampUnixEpoch = ? WHERE ID = ?", m.Title, m.TimeStampUnix, m.Id)
+			if err != nil {
+				return err
+			}
+		}
+	}
+
+	for _, c := range dbMgr.Chapters {
+		count := 0
+		err := db.QueryRow("SELECT COUNT(*) FROM Chapter where ID = ?", c.Id).Scan(&count)
+		if err != nil {
+			return err
+		}
+
+		if count == 0 {
+			_, err := db.Exec("INSERT INTO Chapter(ID, MangaID, Url, Name, Number, TimeStampUnixEpoch) VALUES (?, ?, ?, ?, ?, ?)", c.Id, c.Manga.Id, c.Url, c.Name, c.Number, c.TimeStampUnix)
+			if err != nil {
+				return err
+			}
+		} else {
+			_, err = db.Exec("UPDATE Chapter set Name = ?, Url = ?, Number = ?, TimeStampUnixEpoch = ? where ID = ?", c.Name, c.Url, c.Number, c.TimeStampUnix, c.Id)
+			if err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}
+
+//go:embed createDb.sql
+var createSql string
+
+func (dbMgr *DatabaseManager) createDatabaseIfNotExists() error {
+	_, err := dbMgr.db.Exec(createSql)
+	return err
+}
+
+func (dbMgr *DatabaseManager) load() error {
+	db := dbMgr.db
+	rows, err := db.Query("SELECT * FROM Manga")
+	if err != nil {
+		return err
+	}
+
+	for rows.Next() {
+		manga := Manga{}
+		if err = rows.Scan(&manga.Id, &manga.Title, &manga.TimeStampUnix); err != nil {
+			return err
+		}
+		dbMgr.Mangas[manga.Id] = &manga
+	}
+
+	rows, err = db.Query("SELECT * FROM Chapter")
+	if err != nil {
+		return err
+	}
+
+	for rows.Next() {
+		chapter := Chapter{}
+		var mangaID int
+		if err = rows.Scan(&chapter.Id, &mangaID, &chapter.Url, &chapter.Name, &chapter.Number, &chapter.TimeStampUnix); err != nil {
+			return err
+		}
+
+		chapter.Manga = dbMgr.Mangas[mangaID]
+		if dbMgr.Mangas[mangaID].LatestChapter == nil || dbMgr.Mangas[mangaID].LatestChapter.TimeStampUnix < chapter.TimeStampUnix {
+			dbMgr.Mangas[mangaID].LatestChapter = &chapter
+		}
+
+		dbMgr.Chapters[chapter.Id] = &chapter
+	}
+
+	return nil
+}