validator.go

package main

import (
	"fmt"
	"os"
	"os/user"
)

// Function variables for mocking in tests
var (
	lookupUser  = user.Lookup
	lookupGroup = user.LookupGroup
)

// Validate checks pre-flight requirements for the parsed command.
func Validate(cmd *ParsedCommand) error {
	info, err := os.Stat(cmd.Target)
	if err != nil {
		if os.IsNotExist(err) {
			return fmt.Errorf("target '%s' does not exist", cmd.Target)
		}
		return fmt.Errorf("failed to access target '%s': %v", cmd.Target, err)
	}

	cmd.FileInfo = info

	if cmd.Recursively && !info.IsDir() {
		return fmt.Errorf("cannot apply recursively: target '%s' is not a directory", cmd.Target)
	}

	if cmd.Actor != "" {
		// Handle reserved keywords that map to 'other' UNIX permissions
		if cmd.ActorType == "" && (cmd.Actor == "everyone" || cmd.Actor == "other" || cmd.Actor == "all") {
			cmd.ActorType = "other"
			return nil
		}

		found := false
		var userErr, groupErr error

		if cmd.ActorType == "user" || cmd.ActorType == "" {
			if _, userErr = lookupUser(cmd.Actor); userErr == nil {
				cmd.ActorType = "user"
				found = true
			}
		}

		if !found && (cmd.ActorType == "group" || cmd.ActorType == "") {
			if _, groupErr = lookupGroup(cmd.Actor); groupErr == nil {
				cmd.ActorType = "group"
				found = true
			}
		}

		if !found {
			switch cmd.ActorType {
			case "user":
				return fmt.Errorf("user '%s' not found on system", cmd.Actor)
			case "group":
				return fmt.Errorf("group '%s' not found on system", cmd.Actor)
			default:
				return fmt.Errorf("actor '%s' not found as a user or group on system", cmd.Actor)
			}
		}
	}

	return nil
}