const normalizeStringPosix = (path: string, allowAboveRoot?: boolean) => {
    var res = ""
    var lastSegmentLength = 0
    var lastSlash = -1
    var dots = 0
    var code
    for (var i = 0; i <= path.length; ++i) {
        if (i < path.length) code = path.charCodeAt(i)
        else if (code === 47 /*/*/) break
        else code = 47 /*/*/
        if (code === 47 /*/*/) {
            if (lastSlash === i - 1 || dots === 1) {
                // NOOP
            } else if (lastSlash !== i - 1 && dots === 2) {
                if (
                    res.length < 2 ||
                    lastSegmentLength !== 2 ||
                    res.charCodeAt(res.length - 1) !== 46 /*.*/ ||
                    res.charCodeAt(res.length - 2) !== 46 /*.*/
                ) {
                    if (res.length > 2) {
                        var lastSlashIndex = res.lastIndexOf("/")
                        if (lastSlashIndex !== res.length - 1) {
                            if (lastSlashIndex === -1) {
                                res = ""
                                lastSegmentLength = 0
                            } else {
                                res = res.slice(0, lastSlashIndex)
                                lastSegmentLength =
                                    res.length - 1 - res.lastIndexOf("/")
                            }
                            lastSlash = i
                            dots = 0
                            continue
                        }
                    } else if (res.length === 2 || res.length === 1) {
                        res = ""
                        lastSegmentLength = 0
                        lastSlash = i
                        dots = 0
                        continue
                    }
                }
                if (allowAboveRoot) {
                    if (res.length > 0) res += "/.."
                    else res = ".."
                    lastSegmentLength = 2
                }
            } else {
                if (res.length > 0) res += "/" + path.slice(lastSlash + 1, i)
                else res = path.slice(lastSlash + 1, i)
                lastSegmentLength = i - lastSlash - 1
            }
            lastSlash = i
            dots = 0
        } else if (code === 46 /*.*/ && dots !== -1) {
            ++dots
        } else {
            dots = -1
        }
    }
    return res
}

export default (path: string) => {
    if (path.length === 0) return "."

    var isAbsolute = path.charCodeAt(0) === 47 /*/*/
    var trailingSeparator = path.charCodeAt(path.length - 1) === 47 /*/*/

    // Normalize the path
    path = normalizeStringPosix(path, !isAbsolute)

    if (path.length === 0 && !isAbsolute) path = "."
    if (path.length > 0 && trailingSeparator) path += "/"

    if (isAbsolute) return "/" + path
    return path
}