package fileops

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"
)

// WorkspaceDirectoryMode is the POSIX mode for ordinary, shareable workspace
// directories. The set-group-ID bit preserves the configured workspace group
// for nested files and directories.
const WorkspaceDirectoryMode os.FileMode = os.ModeSetgid | 0o775

// WorkspaceFileMode is the POSIX mode for ordinary, shareable workspace files.
const WorkspaceFileMode os.FileMode = 0o664

// EnsureWorkspaceDirectory creates directory and makes every directory created
// for it conform to the ordinary workspace sharing contract. Existing
// directories retain their owner and group; only their mode is updated.
func EnsureWorkspaceDirectory(directory string) error {
	if strings.TrimSpace(directory) == "" {
		return fmt.Errorf("workspace directory is required")
	}

	clean := filepath.Clean(directory)
	ancestor := clean
	var missing []string
	for {
		info, err := os.Stat(ancestor)
		if err == nil {
			if !info.IsDir() {
				return fmt.Errorf("workspace directory %q is not a directory", ancestor)
			}
			break
		}
		if !os.IsNotExist(err) {
			return fmt.Errorf("inspect workspace directory %q: %w", ancestor, err)
		}
		parent := filepath.Dir(ancestor)
		if parent == ancestor {
			return fmt.Errorf("find workspace directory ancestor for %q", clean)
		}
		missing = append(missing, ancestor)
		ancestor = parent
	}
	for index := len(missing) - 1; index >= 0; index-- {
		created := missing[index]
		if err := os.Mkdir(created, WorkspaceDirectoryMode); err != nil && !os.IsExist(err) {
			return fmt.Errorf("create workspace directory %q: %w", created, err)
		}
		if err := os.Chmod(created, WorkspaceDirectoryMode); err != nil {
			return fmt.Errorf("set workspace directory permissions %q: %w", created, err)
		}
	}
	if err := os.Chmod(clean, WorkspaceDirectoryMode); err != nil {
		return fmt.Errorf("set workspace directory permissions %q: %w", clean, err)
	}
	return nil
}