;;; Chickadee Game Toolkit
;;; Copyright © 2021 David Thompson <dthompson2@worcester.edu>
;;;
;;; Licensed under the Apache License, Version 2.0 (the "License");
;;; you may not use this file except in compliance with the License.
;;; You may obtain a copy of the License at
;;;
;;;    http://www.apache.org/licenses/LICENSE-2.0
;;;
;;; Unless required by applicable law or agreed to in writing, software
;;; distributed under the License is distributed on an "AS IS" BASIS,
;;; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
;;; See the License for the specific language governing permissions and
;;; limitations under the License.

(define-module (chickadee cli)
  #:use-module (chickadee)
  #:use-module (chickadee config)
  #:use-module (ice-9 format)
  #:use-module (ice-9 match)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-37)
  #:export (launch-chickadee
            display-version-and-exit
            leave
            simple-args-fold
            operands))

(define (display-version-and-exit)
  (format #t "Chickadee ~a
Copyright (C) 2021 David Thompson and Chickadee contributors
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.~%"
          %chickadee-version)
  (exit 0))

(define (display-help-and-exit)
  (format #t "Usage: chickadee SUBCOMMAND ARGS ...~%
Run SUBCOMMAND with ARGS

Valid subcommands:
* bundle
* play~%")
  (exit 1))

(define (leave format-string . args)
  "Display error message and exist."
  (apply format (current-error-port) format-string args)
  (newline)
  (exit 1))

(define (simple-args-fold args options defaults)
  (args-fold args options
             (lambda (opt name arg result)
               (leave "unrecognized option: ~A" name))
             (lambda (arg result)
               (alist-cons 'operand arg result))
             defaults))

(define (operands opts)
  (filter-map (match-lambda
                (('operand . arg) arg)
                (_ #f))
              opts))

(define (run-chickadee-command command . args)
  (define (invalid-command)
    (format (current-error-port) "invalid subcommand: ~a~%~%" command)
    (display-help-and-exit))
  (let* ((module
          (catch 'misc-error
            (lambda ()
              (resolve-interface `(chickadee cli ,command)))
            (lambda args
              (invalid-command))))
         (proc-name (symbol-append 'chickadee- command))
         (command-proc (false-if-exception (module-ref module proc-name))))
    (if (procedure? command-proc)
        (apply command-proc args)
        (invalid-command))))

(define (subcommand? arg)
  (not (string-prefix? "-" arg)))

(define (launch-chickadee . args)
  (match args
    ((program (or "--verison" "-v"))
     (display-version-and-exit))
    ((or (program) (program (or "--help" "-h")))
     (display-help-and-exit))
    ((program (? subcommand? subcommand) . args*)
     (apply run-chickadee-command (string->symbol subcommand) args*))
    ((program invalid-subcommand . args*)
     (leave "invalid subcommand: ~A" invalid-subcommand))))