split main.go into modules, add --version flag

ops.go

@@ -0,0 +1,402 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+func applyPackage(filesDir, targetRoot string, cfg *packageConfig) error {
+	if err := ensureDir(targetRoot); err != nil {
+		return err
+	}
+
+	return filepath.WalkDir(filesDir, func(path string, entry fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		if path == filesDir {
+			return nil
+		}
+
+		rel, err := filepath.Rel(filesDir, path)
+		if err != nil {
+			return err
+		}
+
+		if shouldIgnorePath(rel, cfg) {
+			if entry.IsDir() {
+				return filepath.SkipDir
+			}
+			return nil
+		}
+
+		targetPath := filepath.Join(targetRoot, rel)
+
+		if entry.IsDir() {
+			return ensureDir(targetPath)
+		}
+
+		srcAbs, err := filepath.Abs(path)
+		if err != nil {
+			return err
+		}
+		return linkFile(srcAbs, targetPath)
+	})
+}
+
+func linkFile(src, dst string) error {
+	if err := os.MkdirAll(filepath.Dir(dst), 0o755); err != nil {
+		return err
+	}
+
+	if info, err := os.Lstat(dst); err == nil {
+		if info.Mode()&os.ModeSymlink != 0 {
+			current, err := os.Readlink(dst)
+			if err != nil {
+				return err
+			}
+			if current == src {
+				return nil
+			}
+			return fmt.Errorf("conflict at %s (points to %s)", dst, current)
+		}
+		return fmt.Errorf("conflict at %s (exists and is not a symlink)", dst)
+	} else if !errors.Is(err, os.ErrNotExist) {
+		return err
+	}
+
+	return os.Symlink(src, dst)
+}
+
+func ensureDir(path string) error {
+	info, err := os.Lstat(path)
+	if err == nil {
+		if info.IsDir() {
+			return nil
+		}
+		return fmt.Errorf("%s exists and is not a directory", path)
+	}
+	if !errors.Is(err, os.ErrNotExist) {
+		return err
+	}
+	return os.MkdirAll(path, 0o755)
+}
+
+func findStaleLinks(filesDir, targetRoot string) ([]string, error) {
+	filesAbs, err := filepath.Abs(filesDir)
+	if err != nil {
+		return nil, err
+	}
+
+	var stale []string
+	walkErr := filepath.WalkDir(targetRoot, func(path string, entry fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		if entry.IsDir() {
+			return nil
+		}
+
+		info, err := os.Lstat(path)
+		if err != nil {
+			return err
+		}
+		if info.Mode()&os.ModeSymlink == 0 {
+			return nil
+		}
+
+		src, err := os.Readlink(path)
+		if err != nil {
+			return err
+		}
+		if !filepath.IsAbs(src) {
+			src = filepath.Join(filepath.Dir(path), src)
+		}
+		src = filepath.Clean(src)
+
+		if !strings.HasPrefix(src, filesAbs+string(os.PathSeparator)) && src != filesAbs {
+			return nil
+		}
+
+		if _, err := os.Stat(src); errors.Is(err, os.ErrNotExist) {
+			stale = append(stale, path)
+		}
+		return nil
+	})
+
+	if walkErr != nil {
+		return nil, walkErr
+	}
+
+	return stale, nil
+}
+
+func removeLinks(paths []string, dryRun bool) error {
+	for _, path := range paths {
+		if dryRun {
+			fmt.Printf("dry-run: remove %s\n", path)
+			continue
+		}
+		if err := os.Remove(path); err != nil {
+			return err
+		}
+		fmt.Printf("removed %s\n", path)
+	}
+	return nil
+}
+
+func handleStaleLinks(stales []string) error {
+	if len(stales) == 0 {
+		return nil
+	}
+
+	repo, err := repoPath()
+	if err != nil {
+		return err
+	}
+
+	reader := newReader()
+	for _, path := range stales {
+		fmt.Printf("stale: %s\n", path)
+
+		canUnlink, err := staleHasRepoFile(path, repo)
+		if err != nil {
+			return err
+		}
+
+		prompt := "action [p=prune, u=unlink, i=ignore]: "
+		if !canUnlink {
+			prompt = "action [p=prune, i=ignore]: "
+		}
+
+		fmt.Print(prompt)
+		choice, err := reader.ReadString('\n')
+		if err != nil {
+			return err
+		}
+		choice = strings.TrimSpace(strings.ToLower(choice))
+		if choice == "" || choice == "i" {
+			continue
+		}
+		if choice == "p" {
+			if err := os.Remove(path); err != nil {
+				return err
+			}
+			fmt.Printf("removed %s\n", path)
+			continue
+		}
+		if choice == "u" && canUnlink {
+			if err := unlinkStale(path, repo); err != nil {
+				return err
+			}
+			continue
+		}
+		fmt.Println("invalid choice; skipping")
+	}
+
+	return nil
+}
+
+func staleHasRepoFile(targetPath, repo string) (bool, error) {
+	repoPath, err := repoPathForTarget(targetPath, repo)
+	if err != nil {
+		return false, err
+	}
+	if repoPath == "" {
+		return false, nil
+	}
+	if _, err := os.Stat(repoPath); errors.Is(err, os.ErrNotExist) {
+		return false, nil
+	} else if err != nil {
+		return false, err
+	}
+	return true, nil
+}
+
+func unlinkStale(targetPath, repo string) error {
+	repoPath, err := repoPathForTarget(targetPath, repo)
+	if err != nil {
+		return err
+	}
+	if repoPath == "" {
+		return nil
+	}
+
+	if err := os.Remove(targetPath); err != nil {
+		return err
+	}
+
+	if err := copyFile(repoPath, targetPath); err != nil {
+		return err
+	}
+
+	if err := os.Remove(repoPath); err != nil {
+		return err
+	}
+
+	fmt.Printf("unlinked %s (removed %s)\n", targetPath, repoPath)
+	return nil
+}
+
+func restorePackage(filesDir, targetRoot string, dryRun bool) error {
+	filesAbs, err := filepath.Abs(filesDir)
+	if err != nil {
+		return err
+	}
+
+	return filepath.WalkDir(filesDir, func(path string, entry fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		if path == filesDir {
+			return nil
+		}
+		if entry.IsDir() {
+			return nil
+		}
+
+		rel, err := filepath.Rel(filesDir, path)
+		if err != nil {
+			return err
+		}
+		targetPath := filepath.Join(targetRoot, rel)
+		return restoreOne(path, targetPath, filesAbs, dryRun)
+	})
+}
+
+func restorePath(filesDir, targetRoot, relPath string, dryRun bool) error {
+	filesAbs, err := filepath.Abs(filesDir)
+	if err != nil {
+		return err
+	}
+
+	relPath = filepath.Clean(relPath)
+	if strings.HasPrefix(relPath, "..") || filepath.IsAbs(relPath) {
+		return fmt.Errorf("invalid relative path %q", relPath)
+	}
+
+	sourcePath := filepath.Join(filesDir, relPath)
+	info, err := os.Lstat(sourcePath)
+	if err != nil {
+		return err
+	}
+
+	if info.IsDir() {
+		return filepath.WalkDir(sourcePath, func(path string, entry fs.DirEntry, err error) error {
+			if err != nil {
+				return err
+			}
+			if entry.IsDir() {
+				return nil
+			}
+			rel, err := filepath.Rel(filesDir, path)
+			if err != nil {
+				return err
+			}
+			targetPath := filepath.Join(targetRoot, rel)
+			return restoreOne(path, targetPath, filesAbs, dryRun)
+		})
+	}
+
+	rel, err := filepath.Rel(filesDir, sourcePath)
+	if err != nil {
+		return err
+	}
+	return restoreOne(sourcePath, filepath.Join(targetRoot, rel), filesAbs, dryRun)
+}
+
+func restoreOne(sourcePath, targetPath, filesAbs string, dryRun bool) error {
+	info, err := os.Lstat(targetPath)
+	if errors.Is(err, os.ErrNotExist) {
+		return nil
+	}
+	if err != nil {
+		return err
+	}
+	if info.Mode()&os.ModeSymlink == 0 {
+		return nil
+	}
+
+	src, err := os.Readlink(targetPath)
+	if err != nil {
+		return err
+	}
+	if !filepath.IsAbs(src) {
+		src = filepath.Join(filepath.Dir(targetPath), src)
+	}
+	src = filepath.Clean(src)
+
+	if !strings.HasPrefix(src, filesAbs+string(os.PathSeparator)) && src != filesAbs {
+		return nil
+	}
+
+	if dryRun {
+		fmt.Printf("dry-run: restore %s\n", targetPath)
+		return nil
+	}
+
+	if err := os.Remove(targetPath); err != nil {
+		return err
+	}
+
+	fmt.Printf("restored %s\n", targetPath)
+	return copyFile(sourcePath, targetPath)
+}
+
+func copyFile(src, dst string) error {
+	if err := os.MkdirAll(filepath.Dir(dst), 0o755); err != nil {
+		return err
+	}
+
+	srcFile, err := os.Open(src)
+	if err != nil {
+		return err
+	}
+	defer srcFile.Close()
+
+	info, err := srcFile.Stat()
+	if err != nil {
+		return err
+	}
+
+	dstFile, err := os.OpenFile(dst, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, info.Mode())
+	if err != nil {
+		return err
+	}
+	defer dstFile.Close()
+
+	if _, err := io.Copy(dstFile, srcFile); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func moveDirContents(srcDir, destDir string) error {
+	entries, err := os.ReadDir(srcDir)
+	if err != nil {
+		return err
+	}
+
+	for _, entry := range entries {
+		srcPath := filepath.Join(srcDir, entry.Name())
+		destPath := filepath.Join(destDir, entry.Name())
+
+		if _, err := os.Stat(destPath); err == nil {
+			return fmt.Errorf("destination already exists: %s", destPath)
+		} else if !errors.Is(err, os.ErrNotExist) {
+			return err
+		}
+
+		if err := os.Rename(srcPath, destPath); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}