Add legacy solution handling

Adds compatibility for already downloaded exercises

Author: jdsutherland

workspace/solution.go

@@ -2,6 +2,7 @@ package workspace
 
 import (
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -71,7 +72,9 @@ func (s *Solution) Write(dir string) error {
 	}
 
 	path := filepath.Join(dir, ignoreSubdir)
-	_ = os.Mkdir(path, os.FileMode(0755))
+	if err := createIgnoreSubdir(path); err != nil {
+		return err
+	}
 
 	// Hack because ioutil.WriteFile fails on hidden files
 	visibility.ShowFile(path)
@@ -92,3 +95,22 @@ func (s *Solution) PathToParent() string {
 	}
 	return filepath.Join(dir, s.Track)
 }
+
+func createIgnoreSubdir(path string) error {
+	if _, err := os.Stat(path); os.IsNotExist(err) {
+		if err := os.Mkdir(path, os.FileMode(0755)); err != nil {
+			return fmt.Errorf("failed to create directory: %s", path)
+		}
+	}
+	return nil
+}
+
+func migrateLegacySolutionFile(path string, legacySolutionPath string, solutionPath string) error {
+	if err := createIgnoreSubdir(filepath.Join(path, ignoreSubdir)); err != nil {
+		return err
+	}
+	if err := os.Rename(legacySolutionPath, solutionPath); err != nil {
+		return errors.New("failed migrating legacy solution file")
+	}
+	return nil
+}

workspace/workspace.go

@@ -186,14 +186,29 @@ func (ws Workspace) SolutionDir(s string) (string, error) {
 	path := s
 	for {
 		if path == ws.Dir {
-			return "", errors.New("couldn't find it")
+			return "", fmt.Errorf("couldn't find %s", solutionFilename)
 		}
 		if _, err := os.Lstat(path); os.IsNotExist(err) {
 			return "", err
 		}
-		if _, err := os.Lstat(filepath.Join(path, solutionRelPath)); err == nil {
+		if err := checkSolutionFile(path); err == nil {
 			return path, nil
 		}
 		path = filepath.Dir(path)
 	}
 }
+
+func checkSolutionFile(path string) error {
+	legacySolutionPath := filepath.Join(path, ".solution.json")
+	solutionPath := filepath.Join(path, solutionRelPath)
+
+	if _, legacyErr := os.Lstat(legacySolutionPath); legacyErr == nil {
+		return migrateLegacySolutionFile(path, legacySolutionPath, solutionPath)
+	} else if _, err := os.Lstat(solutionPath); err != nil {
+		return err
+	} else if legacyErr != nil && err == nil {
+		return nil
+	} else {
+		return legacyErr
+	}
+}