// Command-path resolution shared by every built-in starter.
//
// Each built-in Starter implements Detect() as
// ResolveCommand(s.command) so cfg.Agents overrides can point
// an agent at a non-PATH location. Absolute paths go through
// os.Stat; relative names resolve via PATH. Path strings are
// stored verbatim (no whitespace splitting) so Windows paths
// with spaces (`C:\Program Files\claude\claude.exe`) survive.
package agent

import (
	"errors"
	"os"
	"os/exec"
	"path/filepath"
)

// ResolveCommand verifies command resolves to an invokable
// binary. Absolute paths are stat-checked and must point at a
// regular file; relative names go through exec.LookPath on
// $PATH.
func ResolveCommand(command string) error {
	if command == "" {
		return errors.New("agent: empty command")
	}
	if filepath.IsAbs(command) {
		info, err := os.Stat(command)
		if err != nil {
			return err
		}
		if info.IsDir() {
			return errors.New("agent: configured path is a directory")
		}
		return nil
	}
	if _, err := exec.LookPath(command); err != nil {
		return err
	}
	return nil
}