#lang racket/base

(require racket/list
         racket/path
         "commands.rkt"
         "env-support.rkt"
         "help.rkt")

(provide dispatch-coreutils-command
         expand-coreutils-arguments)

(define (regexp-paths pattern)
  (define entries
    (directory-list (current-directory) #:build? #t))
  (define matching-entries
    (filter
     (λ (entry)
       (define name (file-name-from-path entry))
       (and name
            (regexp-match? pattern (path->string name))))
     entries))
  (sort matching-entries
        string<?
        #:key
        (λ (entry)
          (path->string (file-name-from-path entry)))))

(define (expand-coreutils-argument arg)
  (cond
    [(list? arg)
     (append-map expand-coreutils-argument arg)]
    [(regexp? arg)
     (define matches (regexp-paths arg))
     (when (null? matches)
       (raise-arguments-error
        'dispatch-coreutils-command
        "regular expression matched no paths"
        "pattern" arg))
     matches]
    [else
     (list arg)]))

(define (expand-coreutils-arguments args)
  (append-map expand-coreutils-argument args))

(define (help-option? arg)
  (or (equal? arg '--help)
      (equal? arg "--help")))

(define (argument->command-name arg)
  (cond
    [(symbol? arg) arg]
    [(string? arg) (string->symbol arg)]
    [(path? arg) (string->symbol (path->string arg))]
    [else #f]))

(define (run-coreutils-command-if-known command)
  (define command-name
    (and (pair? command)
         (argument->command-name (car command))))
  (define known-command
    (and command-name
         (find-coreutils-command command-name)))
  (if known-command
      (begin
        (apply dispatch-coreutils-command command-name (cdr command))
        #t)
      #f))

(define (dispatch-coreutils-command command-name . args)
  (unless (symbol? command-name)
    (raise-argument-error 'dispatch-coreutils-command "symbol?" command-name))
  (define command (find-coreutils-command command-name))
  (unless command
    (raise-arguments-error 'dispatch-coreutils-command
                           "unknown coreutils command"
                           "command" command-name))
  (if (ormap help-option? args)
      (coreutils-help command-name)
      (parameterize ([current-coreutils-command-runner
                      run-coreutils-command-if-known])
        (apply (coreutils-command-procedure command)
               (expand-coreutils-arguments args)))))