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")
	}

	directory = filepath.Clean(directory)
	missing := make([]string, 0)
	for current := directory; ; current = filepath.Dir(current) {
		info, err := os.Lstat(current)
		if err == nil {
			if !info.IsDir() {
				return fmt.Errorf("workspace directory %q is not a directory", current)
			}
			break
		}
		if !os.IsNotExist(err) {
			return fmt.Errorf("inspect workspace directory %q: %w", current, err)
		}
		missing = append(missing, current)
		parent := filepath.Dir(current)
		if parent == current {
			break
		}
	}

	if err := os.MkdirAll(directory, WorkspaceDirectoryMode); err != nil {
		return fmt.Errorf("create workspace directory %q: %w", directory, err)
	}
	for index := len(missing) - 1; index >= 0; index-- {
		if err := os.Chmod(missing[index], WorkspaceDirectoryMode); err != nil {
			return fmt.Errorf("set workspace directory permissions %q: %w", missing[index], err)
		}
	}
	if err := os.Chmod(directory, WorkspaceDirectoryMode); err != nil {
		return fmt.Errorf("set workspace directory permissions %q: %w", directory, err)
	}
	return nil
}