export class Path {
  constructor(private readonly sys: Sys) {}

  private intoStack(pathLike: string): string[] {
    return pathLike.split('/').filter(n => n.length !== 0)
  }

  /** returns true if the path is absolute. */
  public isAbsolute(pathLike: string): boolean {
    return (pathLike.indexOf('/') === 0)
  }
  /** returns the `dirname` path for this path. */
  public dirname(pathLike: string): string {
    const stack = this.intoStack(pathLike)
    stack.pop()
    return stack.length > 0 ? stack.join('/') : '/'
  }

  /** Returns the `basename` for the given path. */
  public basename(pathLike: string): string {
    return this.intoStack(pathLike).pop() || ''
  }

  /** Returns the `extname` for the given path. */
  public extname(pathLike: string): string {
    const stack = this.intoStack(pathLike)
    const last  = stack[stack.length - 1]
    const parts = last.split('.')
    return (!(parts.length === 1 || parts[0].length === 0))
      ? '.' + parts[parts.length - 1]
      : ''
  }

  public join(...pathLikes: string[]): string {
    return ''
  }
  public resolve(pathLike: string): string {
    return ''
  }

  public relative(from: string, to: string): string {
    return ''
  }

  public normalize(pathLike: string): string {
    const absolute = this.isAbsolute(pathLike)
    const normal = this.intoStack(pathLike).reduce((acc, current) => {
      if(current === '..') {
        if(absolute) {
          if(acc.length === 0) {
            return ['']
          } else if (acc[acc.length - 1] !== '..') {
            acc.pop()
            return acc
          } else {
            return [...acc, current]
          }
        } else {
          if(acc.length === 0) {
            return ['..']
          } else if (acc[acc.length - 1] !== '..') {
            acc.pop()
            return acc
          } else {
            return [...acc, current]
          }
        }
      }
      return (current !== '.')
        ? [...acc, current]
        : [...acc]
    }, [] as string[]).join('/')
    return (absolute && normal.indexOf('/') !== 0)
      ? ('/' + normal)
      : normal
  }
}