fs: change Config callback into state based callback #3455

This is a very large change which turns the post Config function in
backends into a state based call and response system so that
alternative user interfaces can be added.

The existing config logic has been converted, but it is quite
complicated and folloup commits will likely be needed to fix it!

Follow up commits will add a command line and API based way of using
this configuration system.

backend/zoho/zoho.go

@@ -72,41 +72,89 @@ func init() {
 		Name:        "zoho",
 		Description: "Zoho",
 		NewFs:       NewFs,
-		Config: func(ctx context.Context, name string, m configmap.Mapper) error {
+		Config: func(ctx context.Context, name string, m configmap.Mapper, config fs.ConfigIn) (*fs.ConfigOut, error) {
 			// Need to setup region before configuring oauth
 			err := setupRegion(m)
 			if err != nil {
-				return err
+				return nil, err
 			}
-			opt := oauthutil.Options{
-				// No refresh token unless ApprovalForce is set
-				OAuth2Opts: []oauth2.AuthCodeOption{oauth2.ApprovalForce},
-			}
-			if err := oauthutil.Config(ctx, "zoho", name, m, oauthConfig, &opt); err != nil {
-				return errors.Wrap(err, "failed to configure token")
-			}
-			// We need to rewrite the token type to "Zoho-oauthtoken" because Zoho wants
-			// it's own custom type
-			token, err := oauthutil.GetToken(name, m)
-			if err != nil {
-				return errors.Wrap(err, "failed to read token")
-			}
-			if token.TokenType != "Zoho-oauthtoken" {
-				token.TokenType = "Zoho-oauthtoken"
-				err = oauthutil.PutToken(name, m, token, false)
+			getSrvs := func() (authSrv, apiSrv *rest.Client, err error) {
+				oAuthClient, _, err := oauthutil.NewClient(ctx, name, m, oauthConfig)
 				if err != nil {
-					return errors.Wrap(err, "failed to configure token")
+					return nil, nil, errors.Wrap(err, "failed to load oAuthClient")
 				}
+				authSrv = rest.NewClient(oAuthClient).SetRoot(accountsURL)
+				apiSrv = rest.NewClient(oAuthClient).SetRoot(rootURL)
+				return authSrv, apiSrv, nil
 			}
 
-			if fs.GetConfig(ctx).AutoConfirm {
-				return nil
-			}
+			switch config.State {
+			case "":
+				return oauthutil.ConfigOut("teams", &oauthutil.Options{
+					OAuth2Config: oauthConfig,
+					// No refresh token unless ApprovalForce is set
+					OAuth2Opts: []oauth2.AuthCodeOption{oauth2.ApprovalForce},
+				})
+			case "teams":
+				// We need to rewrite the token type to "Zoho-oauthtoken" because Zoho wants
+				// it's own custom type
+				token, err := oauthutil.GetToken(name, m)
+				if err != nil {
+					return nil, errors.Wrap(err, "failed to read token")
+				}
+				if token.TokenType != "Zoho-oauthtoken" {
+					token.TokenType = "Zoho-oauthtoken"
+					err = oauthutil.PutToken(name, m, token, false)
+					if err != nil {
+						return nil, errors.Wrap(err, "failed to configure token")
+					}
+				}
 
-			if err = setupRoot(ctx, name, m); err != nil {
-				return errors.Wrap(err, "failed to configure root directory")
+				authSrv, apiSrv, err := getSrvs()
+				if err != nil {
+					return nil, err
+				}
+
+				// Get the user Info
+				opts := rest.Opts{
+					Method: "GET",
+					Path:   "/oauth/user/info",
+				}
+				var user api.User
+				_, err = authSrv.CallJSON(ctx, &opts, nil, &user)
+				if err != nil {
+					return nil, err
+				}
+
+				// Get the teams
+				teams, err := listTeams(ctx, user.ZUID, apiSrv)
+				if err != nil {
+					return nil, err
+				}
+				return fs.ConfigChoose("workspace", "Team Drive ID", len(teams), func(i int) (string, string) {
+					team := teams[i]
+					return team.ID, team.Attributes.Name
+				})
+			case "workspace":
+				_, apiSrv, err := getSrvs()
+				if err != nil {
+					return nil, err
+				}
+				teamID := config.Result
+				workspaces, err := listWorkspaces(ctx, teamID, apiSrv)
+				if err != nil {
+					return nil, err
+				}
+				return fs.ConfigChoose("workspace_end", "Workspace ID", len(workspaces), func(i int) (string, string) {
+					workspace := workspaces[i]
+					return workspace.ID, workspace.Attributes.Name
+				})
+			case "workspace_end":
+				worksspaceID := config.Result
+				m.Set(configRootID, worksspaceID)
+				return nil, nil
 			}
-			return nil
+			return nil, fmt.Errorf("unknown state %q", config.State)
 		},
 		Options: append(oauthutil.SharedOptions, []fs.Option{{
 			Name: "region",
@@ -209,49 +257,6 @@ func listWorkspaces(ctx context.Context, teamID string, srv *rest.Client) ([]api
 	return workspaceList.TeamWorkspace, nil
 }
 
-func setupRoot(ctx context.Context, name string, m configmap.Mapper) error {
-	oAuthClient, _, err := oauthutil.NewClient(ctx, name, m, oauthConfig)
-	if err != nil {
-		return errors.Wrap(err, "failed to load oAuthClient")
-	}
-	authSrv := rest.NewClient(oAuthClient).SetRoot(accountsURL)
-	opts := rest.Opts{
-		Method: "GET",
-		Path:   "/oauth/user/info",
-	}
-
-	var user api.User
-	_, err = authSrv.CallJSON(ctx, &opts, nil, &user)
-	if err != nil {
-		return err
-	}
-
-	apiSrv := rest.NewClient(oAuthClient).SetRoot(rootURL)
-	teams, err := listTeams(ctx, user.ZUID, apiSrv)
-	if err != nil {
-		return err
-	}
-	var teamIDs, teamNames []string
-	for _, team := range teams {
-		teamIDs = append(teamIDs, team.ID)
-		teamNames = append(teamNames, team.Attributes.Name)
-	}
-	teamID := config.Choose("Enter a Team Drive ID", teamIDs, teamNames, true)
-
-	workspaces, err := listWorkspaces(ctx, teamID, apiSrv)
-	if err != nil {
-		return err
-	}
-	var workspaceIDs, workspaceNames []string
-	for _, workspace := range workspaces {
-		workspaceIDs = append(workspaceIDs, workspace.ID)
-		workspaceNames = append(workspaceNames, workspace.Attributes.Name)
-	}
-	worksspaceID := config.Choose("Enter a Workspace ID", workspaceIDs, workspaceNames, true)
-	m.Set(configRootID, worksspaceID)
-	return nil
-}
-
 // --------------------------------------------------------------
 
 // retryErrorCodes is a slice of error codes that we will retry