feat(offline_download): add simple http tool (close #4002)

internal/offline_download/http/client.go

@@ -0,0 +1,85 @@
+package http
+
+import (
+	"fmt"
+	"github.com/alist-org/alist/v3/internal/model"
+	"github.com/alist-org/alist/v3/internal/offline_download/tool"
+	"github.com/alist-org/alist/v3/pkg/utils"
+	"net/http"
+	"net/url"
+	"os"
+	"path"
+	"path/filepath"
+)
+
+type SimpleHttp struct {
+	client http.Client
+}
+
+func (s SimpleHttp) Name() string {
+	return "SimpleHttp"
+}
+
+func (s SimpleHttp) Items() []model.SettingItem {
+	return nil
+}
+
+func (s SimpleHttp) Init() (string, error) {
+	return "ok", nil
+}
+
+func (s SimpleHttp) IsReady() bool {
+	return true
+}
+
+func (s SimpleHttp) AddURL(args *tool.AddUrlArgs) (string, error) {
+	panic("should not be called")
+}
+
+func (s SimpleHttp) Remove(task *tool.DownloadTask) error {
+	panic("should not be called")
+}
+
+func (s SimpleHttp) Status(task *tool.DownloadTask) (*tool.Status, error) {
+	panic("should not be called")
+}
+
+func (s SimpleHttp) Run(task *tool.DownloadTask) error {
+	u := task.Url
+	// parse url
+	_u, err := url.Parse(u)
+	if err != nil {
+		return err
+	}
+	req, err := http.NewRequestWithContext(task.Ctx(), http.MethodGet, u, nil)
+	if err != nil {
+		return err
+	}
+	resp, err := s.client.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode >= 400 {
+		return fmt.Errorf("http status code %d", resp.StatusCode)
+	}
+	filename := path.Base(_u.Path)
+	if n, err := parseFilenameFromContentDisposition(resp.Header.Get("Content-Disposition")); err == nil {
+		filename = n
+	}
+	// save to temp dir
+	_ = os.MkdirAll(task.TempDir, os.ModePerm)
+	filePath := filepath.Join(task.TempDir, filename)
+	file, err := os.Create(filePath)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+	fileSize := resp.ContentLength
+	err = utils.CopyWithCtx(task.Ctx(), file, resp.Body, fileSize, task.SetProgress)
+	return err
+}
+
+func init() {
+	tool.Tools.Add(&SimpleHttp{})
+}