package openfolder

import (
	"errors"
	"os/exec"
	"strings"
)

// OpenLocationCustom executes a user-defined command string, substituting %1
// with the given path. The command string is split into executable + arguments
// using shell-like quoting rules (double quotes are respected).
//
// Example command: doublecmd.exe -C -T -P L -L "%1"
func OpenLocationCustom(command string, path string) error {
	expanded := strings.ReplaceAll(command, "%1", path)

	args, err := splitCommand(expanded)
	if err != nil {
		return err
	}
	if len(args) == 0 {
		return errors.New("open_location_command: empty command after expansion")
	}

	return exec.Command(args[0], args[1:]...).Start()
}

// splitCommand splits a command string into tokens, respecting double-quoted
// segments. Quotes are removed from the resulting tokens. Backslash escaping
// of a double quote (\") inside a quoted segment is supported.
func splitCommand(s string) ([]string, error) {
	var tokens []string
	var current strings.Builder
	inQuote := false
	hasToken := false

	for i := 0; i < len(s); i++ {
		ch := s[i]

		switch {
		case ch == '"':
			inQuote = !inQuote
			hasToken = true // even empty quotes produce a token part

		case ch == '\\' && inQuote && i+1 < len(s) && s[i+1] == '"':
			// escaped quote inside a quoted segment
			current.WriteByte('"')
			i++ // skip the next quote

		case (ch == ' ' || ch == '\t') && !inQuote:
			if hasToken {
				tokens = append(tokens, current.String())
				current.Reset()
				hasToken = false
			}

		default:
			current.WriteByte(ch)
			hasToken = true
		}
	}

	if inQuote {
		return nil, errors.New("open_location_command: unterminated double quote")
	}

	if hasToken {
		tokens = append(tokens, current.String())
	}

	return tokens, nil
}