added: feature request for restart command

cmd/restart.go

@@ -0,0 +1,246 @@
+package cmd
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"net/http"
+	netURL "net/url"
+	"os"
+	"path/filepath"
+
+	"github.com/exercism/cli/api"
+	"github.com/exercism/cli/config"
+	"github.com/spf13/cobra"
+	"github.com/spf13/pflag"
+	"github.com/spf13/viper"
+)
+
+// restartCmd represents the restart command
+var restartCmd = &cobra.Command{
+	Use:     "restart",
+	Aliases: []string{"r"},
+	Short:   "Restart an exercise.",
+	Long: `Restart an exercise.
+
+You may restart an exercise to work on. If you've already
+started working on it, the command will override your local solution.
+`,
+	RunE: func(cmd *cobra.Command, args []string) error {
+		cfg := config.NewConfig()
+
+		v := viper.New()
+		v.AddConfigPath(cfg.Dir)
+		v.SetConfigName("user")
+		v.SetConfigType("json")
+		// Ignore error. If the file doesn't exist, that is fine.
+		_ = v.ReadInConfig()
+		cfg.UserViperConfig = v
+
+		return runRestart(cfg, cmd.Flags(), args)
+	},
+}
+
+func runRestart(cfg config.Config, flags *pflag.FlagSet, args []string) error {
+	usrCfg := cfg.UserViperConfig
+	if err := validateUserConfig(usrCfg); err != nil {
+		return err
+	}
+
+	download, err := newRestart(flags, usrCfg)
+	if err != nil {
+		return err
+	}
+
+	metadata := download.payload.metadata()
+	dir := metadata.Exercise(usrCfg.GetString("workspace")).MetadataDir()
+
+	if err := os.MkdirAll(dir, os.FileMode(0755)); err != nil {
+		return err
+	}
+
+	if err := metadata.Write(dir); err != nil {
+		return err
+	}
+
+	client, err := api.NewClient(usrCfg.GetString("token"), usrCfg.GetString("apibaseurl"))
+	if err != nil {
+		return err
+	}
+
+	for _, sf := range download.payload.files() {
+		url, err := sf.url()
+		if err != nil {
+			return err
+		}
+
+		req, err := client.NewRequest("GET", url, nil)
+		if err != nil {
+			return err
+		}
+
+		res, err := client.Do(req)
+		if err != nil {
+			return err
+		}
+		defer res.Body.Close()
+
+		if res.StatusCode != http.StatusOK {
+			// TODO: deal with it
+			continue
+		}
+		// Don't bother with empty files.
+		if res.Header.Get("Content-Length") == "0" {
+			continue
+		}
+
+		path := sf.relativePath()
+		dir := filepath.Join(metadata.Dir, filepath.Dir(path))
+		if err = os.MkdirAll(dir, os.FileMode(0755)); err != nil {
+			return err
+		}
+
+		f, err := os.Create(filepath.Join(metadata.Dir, path))
+		if err != nil {
+			return err
+		}
+		defer f.Close()
+		_, err = io.Copy(f, res.Body)
+		if err != nil {
+			return err
+		}
+	}
+	fmt.Fprintf(Err, "\nDownloaded to\n")
+	fmt.Fprintf(Out, "%s\n", metadata.Dir)
+	return nil
+}
+
+type restart struct {
+	// exercise
+	slug string
+
+	// user config
+	token, apibaseurl, workspace string
+
+	// optional
+	track string
+
+	payload *downloadPayload
+}
+
+func newRestart(flags *pflag.FlagSet, usrCfg *viper.Viper) (*restart, error) {
+	var err error
+	r := &restart{}
+	r.slug, err = flags.GetString("exercise")
+	if err != nil {
+		return nil, err
+	}
+	r.track, err = flags.GetString("track")
+	if err != nil {
+		return nil, err
+	}
+
+	r.token = usrCfg.GetString("token")
+	r.apibaseurl = usrCfg.GetString("apibaseurl")
+	r.workspace = usrCfg.GetString("workspace")
+
+	if err = r.needsSlug(); err != nil {
+		return nil, err
+	}
+	if err = r.needsUserConfigValues(); err != nil {
+		return nil, err
+	}
+	if err = r.needsSlugWhenGivenTrack(); err != nil {
+		return nil, err
+	}
+
+	client, err := api.NewClient(r.token, r.apibaseurl)
+	if err != nil {
+		return nil, err
+	}
+
+	req, err := client.NewRequest("GET", r.url(), nil)
+	if err != nil {
+		return nil, err
+	}
+	r.buildQueryParams(req.URL)
+
+	res, err := client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer res.Body.Close()
+
+	if res.StatusCode < 200 || res.StatusCode > 299 {
+		return nil, decodedAPIError(res)
+	}
+
+	body, _ := ioutil.ReadAll(res.Body)
+	res.Body = ioutil.NopCloser(bytes.NewReader(body))
+
+	if err := json.Unmarshal(body, &r.payload); err != nil {
+		return nil, decodedAPIError(res)
+	}
+
+	return r, nil
+}
+
+func (r restart) url() string {
+	id := "latest"
+	return fmt.Sprintf("%s/solutions/%s", r.apibaseurl, id)
+}
+
+func (r restart) buildQueryParams(url *netURL.URL) {
+	query := url.Query()
+	if r.slug != "" {
+		query.Add("exercise_id", r.slug)
+		if r.track != "" {
+			query.Add("track_id", r.track)
+		}
+	}
+	url.RawQuery = query.Encode()
+}
+
+// needsSlug checks the presence of slug.
+func (r restart) needsSlug() error {
+	if r.slug != "" {
+		return errors.New("need an --exercise name")
+	}
+	return nil
+}
+
+// needsUserConfigValues checks the presence of required values from the user config.
+func (r restart) needsUserConfigValues() error {
+	errMsg := "missing required user config: '%s'"
+	if r.token == "" {
+		return fmt.Errorf(errMsg, "token")
+	}
+	if r.apibaseurl == "" {
+		return fmt.Errorf(errMsg, "apibaseurl")
+	}
+	if r.workspace == "" {
+		return fmt.Errorf(errMsg, "workspace")
+	}
+	return nil
+}
+
+// needsSlugWhenGivenTrack ensures that track arguments are also given with a slug.
+func (r restart) needsSlugWhenGivenTrack() error {
+	if (r.track != "") && r.slug == "" {
+		return errors.New("--track requires --exercise")
+	}
+	return nil
+}
+
+func setupRestartFlags(flags *pflag.FlagSet) {
+	flags.StringP("track", "t", "", "the track ID")
+	flags.StringP("exercise", "e", "", "the exercise slug")
+}
+
+func init() {
+	RootCmd.AddCommand(restartCmd)
+	setupRestartFlags(restartCmd.Flags())
+}