;;; makefile.lisp --- GNU Makefile compiler

 ;; GNU Makefile compiler.

 ;;; Commentary:

 ;; Makefiles are our 'portable' build medium. We can parse them using

 ;; the same general strategy as GNU make and compile them from

 ;; skelfiles (rule, source, target, command).

 ;;  HACK 2023-09-15: MVP

 ;; SO, the absolute priority ATM is to transpile our `sk-rule' objects

 ;; into a working Makefile. We're ignoring most of the niceties like

 ;; line-splitting and any JIT or compile-time execution.

 ;; https://github.com/takagi/lake

 ;; https://www.gnu.org/software/make/manual/html_node/Parsing-Makefiles.html

 ;;; Code:

 (in-package :skel/comp)

 (defparameter *default-makefile* "makefile")

 (defparameter *makefile-extension* "mk")

 ;;  TODO 2023-09-27: what is $(@D) ?? (target-dir)

 (defvar *mk-magic-vars* #(#\@ #\< #\^ #\* #\+ #\? #\|))

 (defvar *mk-command-prefixes* #(#\@ #\- #\+))

 (deftype mk-val-designator () '(member nil :simple :immediate :conditional :recursive :once :append :shell))

 (defstruct mk-val "" (kind nil :type mk-val-designator)  (val nil :type sxp:form))

 (defstruct mk-var ""

 	   (key "" :type string)

 	   (val (make-mk-val) :type mk-val))

 ;; https://www.gnu.org/software/make/manual/html_node/Makefile-Contents.html

 (defclass makefile (skel sk-meta)

   ((directives :initform (make-array 0 :element-type 'sk-command :adjustable t :fill-pointer 0) 

 	       :type (vector sk-command) :accessor mk-directives)

    (variables :initform (make-hash-table) 

 	      :type (hash-table) :accessor mk-vars)

    (explicit :initform (make-array 0 :element-type 'sk-rule :adjustable t :fill-pointer 0)

 	     :type (vector sk-rule) :accessor mk-erules)

    (implicit :initform (make-array 0 :element-type 'sk-rule :adjustable t :fill-pointer 0) 

 	     :type (vector sk-rule) :accessor mk-irules))

   (:documentation "A virtual GNU Makefile."))

 (defmethod push-rule ((self sk-rule) (place makefile) &optional implicit)

   (if implicit

       (vector-push-extend self (mk-irules place))

       (vector-push-extend self (mk-erules place))))

 (defmethod push-directive ((self sk-command) (place makefile))

   (vector-push-extend self (mk-directives place)))

 (defmethod push-var ((self cons) (place makefile))

   (destructuring-bind (k v) self

     (setf (gethash k (mk-vars place)) v)))

 (defmethod sk-compile ((self makefile) stream &key &allow-other-keys)

   "Compile the makefile SELF to output STREAM."

   (with-open-stream (s stream)

     (with-slots (directives variables explicit implicit) self

       ;; directives

       (loop for d across directives

 	    do (sk-writeln d s))

       ;; variables

       (maphash (lambda (x y) (format s "~A=~A~%" x y)) variables)

       ;; explicit rules

       (loop for exp across explicit

 	    do (format s "~A:~A;~A~%" 

 		       (sk-write-string (sk-rule-target exp))

 		       (sk-write-string (sk-rule-source exp))

 		       (sk-write-string (sk-rule-recipe exp))))

       ;; TODO implicit rules

       (loop for imp across implicit

 	    do (format s "~A:~A;~A~%" 

 		       (sk-write-string (sk-rule-target imp))

 		       (sk-write-string (sk-rule-source imp))

 		       (sk-write-string (sk-rule-recipe imp)))))))

 (defmethod sk-write-file ((self makefile) &key (path *default-makefile*) (comment t) (if-exists :overwrite))

   (with-open-file (out path

 		       :direction :output

 		       :if-exists if-exists

 		       :if-does-not-exist :create)

     (when comment (princ

 		   (make-source-header-comment

 		    (sk-name self)

 		    :cchar #\#

 		    :timestamp t

 		    :description (sk-description self)

 		    :opts '("mode: makefile-gmake;"))

 		   out))

     (sk-compile self out)))

 (defmethod sk-read-file ((self makefile) path)