support: Continue an incomplete download:

.gitignore

@@ -1,2 +1,3 @@
 dl-talebook.exe
-dl-talebook
+dl-talebook
+*.log

main.go

@@ -11,16 +11,17 @@ import (
 )
 
 var (
-	userAgent  = `Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.4844.51 Safari/537.36`
-	site       = `https://book.codefine.site:6870/`
-	cookie     = ""
-	dir        = "./"
-	timeout    = time.Duration(10) * time.Second
-	username   = ""
-	password   = ""
-	verbose    = false
-	startIndex = 0
-	version    = false
+	userAgent       = `Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.4844.51 Safari/537.36`
+	site            = `https://book.codefine.site:6870/`
+	cookie          = ""
+	dir             = "./"
+	timeout         = time.Duration(10) * time.Second
+	username        = ""
+	password        = ""
+	verbose         = false
+	startIndex      = 0
+	version         = false
+	continueOnStart = false
 )
 
 func init() {
@@ -35,6 +36,7 @@ func init() {
 	flag.DurationVar(&timeout, "timeout", timeout, "http timeout")
 	flag.BoolVar(&verbose, "verbose", false, "show debug log")
 	flag.BoolVar(&version, "version", false, "show progream version")
+	flag.BoolVar(&continueOnStart, "continue", true, "continue an incomplete download")
 
 	flag.IntVar(&startIndex, "start-index", startIndex, "start book id")
 
@@ -53,6 +55,7 @@ func main() {
 		WithTimeOutOption(timeout),
 		WithStartIndex(startIndex),
 		WithLoginOption(username, password),
+		WithContinue(continueOnStart),
 	)
 
 	if err != nil {

talbook_log.go

@@ -0,0 +1,38 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/url"
+	"os"
+	"strconv"
+	"strings"
+)
+
+const (
+	logfile = `.dl-download.log`
+)
+
+func saveDownloadHistory(tb TaleBook) {
+	u, _ := url.Parse(tb.api)
+
+	if err := os.WriteFile(logfile, []byte(fmt.Sprintf("%s %d", u.Host, tb.index)), 0644); err != nil {
+		log.Printf("warning: can not write dl-download infromat to .dl-download.log %s", err)
+	}
+}
+
+func tryReadHistoryIndex(api string) (int, error) {
+	content, err := os.ReadFile(logfile)
+	if err != nil {
+		return 0, err
+	}
+	u, err := url.Parse(api)
+	if err != nil {
+		return 0, nil
+	}
+	result := strings.Split(string(content), " ")
+	if len(result) >= 2 && result[0] == u.Host {
+		return strconv.Atoi(result[1])
+	}
+	return 0, fmt.Errorf("prase .dl-download.log failed , content: %s", string(content))
+}

talebook.go

@@ -10,8 +10,10 @@ import (
 	"net/http/cookiejar"
 	"net/url"
 	"os"
+	"os/signal"
 	"path/filepath"
 	"strings"
+	"syscall"
 	"time"
 )
 
@@ -59,6 +61,7 @@ type TaleBook struct {
 	serverInfo ServerInfo
 	MaxIndex   int
 	Total      int
+	exit       func()
 }
 
 type Book struct {
@@ -217,6 +220,28 @@ func NewTableBook(site string, opstions ...func(*TaleBook)) (*TaleBook, error) {
 
 	tb.getInfo()
 
+	// try to recovery from last download action
+	if tb.exit != nil {
+
+		index, err := tryReadHistoryIndex(tb.api)
+		if tb.verbose {
+			log.Printf(err.Error())
+		}
+		if tb.index == 0 && index != 0 {
+			log.Printf("resume download from last id %d, resuming", index)
+			tb.index = index
+		}
+
+		// save download index before exit
+		c := make(chan os.Signal)
+		signal.Notify(c, os.Interrupt, syscall.SIGTERM)
+		go func() {
+			<-c
+			tb.exit()
+			os.Exit(1)
+		}()
+	}
+
 	return tb, tb.err
 }
 
@@ -308,6 +333,17 @@ func WithStartIndex(index int) func(*TaleBook) {
 		tb.index = index
 	}
 }
+
+func WithContinue(c bool) func(*TaleBook) {
+	return func(tb *TaleBook) {
+		if c {
+			tb.exit = func() {
+				saveDownloadHistory(*tb)
+			}
+		}
+
+	}
+}
 func (tb *TaleBook) LastIndex() int {
 	var m = tb.Total
 	for _, book := range tb.serverInfo.Books {