;;;; Cyclone Scheme
;;;; https://github.com/justinethier/cyclone
;;;;
;;;; Copyright (c) 2014-2016, Justin Ethier
;;;; All rights reserved.
;;;;
;;;; This module contains a front-end for the compiler itself.
;;;;
(import (scheme base)
        (scheme case-lambda)
        (scheme eval)
        (scheme file)
        (scheme lazy)
        (scheme read)
        (scheme write)
        (scheme cyclone ast)
        (scheme cyclone common)
        (scheme cyclone util)
        (scheme cyclone cgen)
        (scheme cyclone transforms)
        (scheme cyclone cps-optimizations)
        (scheme cyclone macros)
        (scheme cyclone libraries))

(define *optimization-level* 2) ;; Default level

;; Code emission.
  
; c-compile-and-emit : (string -> A) exp -> void
(define (c-compile-and-emit input-program program:imports/code 
                            lib-deps src-file append-dirs prepend-dirs)
  (call/cc 
    (lambda (return)
      (define globals '())
      (define module-globals '()) ;; Globals defined by this module
      (define program? #t) ;; Are we building a program or a library?
      (define imports '())
      (define imported-vars '())
      (define lib-name '())
      (define lib-exports '())
      (define lib-renamed-exports '())
      (define lib-pass-thru-exports '())
      (define c-headers '())
      (define rename-env (env:extend-environment '() '() '()))

      (emit *c-file-header-comment*) ; Guarantee placement at top of C file
    
      (trace:info "---------------- input program:")
      (trace:info input-program) ;pretty-print

      (cond
        ((library? (car input-program))
         (let ((includes (lib:includes (car input-program))))
           (set! program? #f)
           (set! lib-name (lib:name (car input-program)))
           (set! c-headers (lib:include-c-headers (car input-program)))
           (set! lib-exports
             (cons
               (lib:name->symbol lib-name)
               (lib:exports (car input-program))))
           (set! lib-pass-thru-exports lib-exports)
           (set! lib-renamed-exports 
             (lib:rename-exports (car input-program)))
           (set! imports (lib:imports (car input-program)))
           (set! input-program (lib:body (car input-program)))
           ;; Add any renamed exports to the begin section
           (set! input-program
                 (append
                   (map 
                     (lambda (r) 
                      `(define ,(caddr r) ,(cadr r)))
                     lib-renamed-exports)   
                   input-program))
           ;; Prepend any included files into the begin section
           (if (not (null? includes))
             (for-each
               (lambda (include)
                 (set! input-program 
                       (append (read-file ;(string-append 
                                            (lib:import->path lib-name append-dirs prepend-dirs include) 
                                            ;include)
                       ) 
                               input-program)))
               (reverse includes))))) ;; Append code in same order as the library's includes
        (else
          ;; Handle imports, if present
          (let ((reduction program:imports/code))
            (set! imports (car reduction))
            (set! input-program (cdr reduction)))

          ;; Handle any C headers
          (let ((headers (lib:include-c-headers `(dummy dummy ,@input-program))))
            (cond
              ((not (null? headers))
               (set! c-headers headers)
               (set! input-program 
                     (filter 
                       (lambda (expr)
                         (not (tagged-list? 'include-c-header expr)))
                       input-program)))))
        ))

      ;; Process library imports
      (trace:info "imports:")
      (trace:info imports)
      (set! imported-vars (lib:imports->idb imports append-dirs prepend-dirs))
      (trace:info "resolved imports:")
      (trace:info imported-vars)
      (let ((meta (lib:resolve-meta imports append-dirs prepend-dirs)))
        (set! *defined-macros* (append meta *defined-macros*))
        (trace:info "resolved macros:")
        (trace:info meta))

      ;; TODO: how to handle stdlib when compiling a library??
      ;; either need to keep track of what was actually used,
      ;; or just assume all imports were used and include them
      ;; in final compiled program
      ;(set! input-program (add-libs input-program))
    
      ;; Load macros for expansion phase
      (let ((macros (filter 
                      (lambda (v) 
                        (Cyc-macro? (Cyc-get-cvar (cdr v))))
                      (Cyc-global-vars))))
        (set! *defined-macros*
              (append
                macros
                *defined-macros*)))
      (macro:load-env! *defined-macros* (create-environment '() '()))

      ;; Expand macros
      ;; In each case, the input is expanded in a way that ensures
      ;; defines from any top-level begins are spliced correctly.
      (set! input-program 
        (cond
          (program?
            (expand-lambda-body input-program (macro:get-env) rename-env))
          (else
            (let ((expanded (expand `(begin ,@input-program) 
                                    (macro:get-env)
                                    rename-env)))
              (cond
                ((and (pair? expanded)
                      (tagged-list? 'lambda (car expanded)))
                 (lambda->exp (car expanded)))
                ((tagged-list? 'define expanded)
                 (list expanded))
                ((boolean? expanded)
                 (list expanded))
                (else
                  (error `(Unhandled expansion ,expanded))))))))
      (trace:info "---------------- after macro expansion:")
      (trace:info input-program) ;pretty-print
; TODO:
      (set! input-program (macro:cleanup input-program rename-env))
      (trace:info "---------------- after macro expansion cleanup:")
      (trace:info input-program) ;pretty-print

      ;; Separate global definitions from the rest of the top-level code
      (set! input-program 
          (isolate-globals input-program program? lib-name rename-env))

      ;; Optimize-out unused global variables
      ;; For now, do not do this if eval is used.
      ;; TODO: do not have to be so aggressive, unless (eval (read)) or such
      (if (not (has-global? input-program 'eval))
          (set! input-program 
            (filter-unused-variables input-program lib-exports)))

      (trace:info "---------------- after processing globals")
      (trace:info input-program) ;pretty-print

      ;; Identify global variables
      (set! module-globals (global-vars input-program))
      (set! globals (append (lib:idb:ids imported-vars) module-globals))

      ;; Trim down the export list to any exports that are just "pass throughs"
      ;; from imported libraries. That is, they are not actually defined in
      ;; the library being compiled
      (set! lib-pass-thru-exports
        (filter
          (lambda (e)
            (let ((module-global? (member e module-globals))
                  (imported-var? (assoc e imported-vars)))
              (cond
                ((eq? e 'call/cc) #f) ;; Special case
                ((and (not module-global?)
                      (not imported-var?))
                 (error "Identifier is exported but not defined" e))
                (else
                  ;; Pass throughs are not defined in this module,
                  ;; but by definition must be defined in an imported lib
                  (and (not module-global?) imported-var?)))))
          lib-pass-thru-exports))
      (trace:info "pass thru exports:")
      (trace:info lib-pass-thru-exports)
    
      ; Note alpha-conversion is overloaded to convert internal defines to 
      ; set!'s below, since all remaining phases operate on set!, not define.
      ;
      ; TODO: consider moving some of this alpha-conv logic below back into trans?
      (set! input-program 
        (map
          (lambda (expr)
            (alpha-convert expr globals return))
          input-program))
      (trace:info "---------------- after alpha conversion:")
      (trace:info input-program) ;pretty-print

      ;; Convert some function calls to primitives, if possible
      (set! input-program 
        (map
          (lambda (expr)
            (prim-convert expr))
          input-program))
      (trace:info "---------------- after func->primitive conversion:")
      (trace:info input-program) ;pretty-print
    
      (let ((cps (map 
                   (lambda (expr)
                     (cps-convert expr))
                   input-program)))
        (cond
         ((and library? (equal? lib-name '(scheme base)))
           (set! globals (append '(call/cc) globals))
           (set! module-globals (append '(call/cc) module-globals))
           (set! input-program 
             ;(cons
             ; ;; Experimental version of call-with-values,
             ; ;; seems OK in compiler but not in eval.
             ; '(define call-with-values
             ;   (lambda (k producer consumer)
             ;     (let ((x (producer)))
             ;       (if (and (pair? x) (equal? '(multiple values) (car x)))
             ;         (apply consumer (cdr x))
             ;         (consumer k x))))
             ;   ;  (producer 
             ;   ;    (lambda (result)
             ;   ;      (consumer k result))))
             ;   )
                    ;; multiple args requires more than just this.
                    ;; may want to look at:
                    ;; http://stackoverflow.com/questions/16674214/how-to-implement-call-with-values-to-match-the-values-example-in-r5rs
                    ;; (lambda vals
                    ;;   (apply k consumer vals)))))
             (cons
               ;; call/cc must be written in CPS form, so it is added here
               ;; TODO: prevents this from being optimized-out
               ;; TODO: will this cause issues if another var is assigned to call/cc?
               `(define call/cc
                 ,(ast:make-lambda 
                    '(k f) 
                    (list 
                      (list 'f 'k 
                            (ast:make-lambda '(_ result) 
                                             (list '(k result)))))))
                 ;(lambda (k f) (f k (lambda (_ result) (k result)))))
                cps)));)
         (else
           ;; No need for call/cc yet
           (set! input-program cps))))
      (trace:info "---------------- after CPS:")
      (trace:info input-program) ;pretty-print

      (when (> *optimization-level* 0)
        (set! input-program
          (optimize-cps input-program))
        (trace:info "---------------- after cps optimizations:")
        (trace:info input-program))
    
      (set! input-program
        (map
          (lambda (expr)
            (clear-mutables)
            (analyze-mutable-variables expr)
            (wrap-mutables expr globals))
          input-program))
      (trace:info "---------------- after wrap-mutables:")
      (trace:info input-program) ;pretty-print
    
      (set! input-program 
        (map
          (lambda (expr)
            (cond
             ((define? expr)
              ;; Global
              `(define ,(define->var expr)
                 ,@(caddr (closure-convert (define->exp expr) globals))))
             ((define-c? expr)
              expr)
             (else
              (caddr ;; Strip off superfluous lambda
                (closure-convert expr globals)))))
          input-program))
    ;    (caddr ;; Strip off superfluous lambda
    ;      (closure-convert input-program)))
      (trace:info "---------------- after closure-convert:")
      (trace:info input-program) ;pretty-print
      
      (when (not *do-code-gen*)
        (trace:error "DEBUG, existing program")
        (exit 0))
    
      (trace:info "---------------- C headers: ")
      (trace:info c-headers)

      (trace:info "---------------- C code:")
      (mta:code-gen input-program 
                    program? 
                    lib-name 
                    lib-pass-thru-exports
                    imported-vars
                    module-globals
                    c-headers
                    lib-deps
                    src-file) 
      (return '())))) ;; No codes to return

;; Read top-level imports from a program and return a cons of:
;; - imports
;; - remaining program
(define (import-reduction expr expander)
  (let ((results
          (foldl
            (lambda (ex accum)
              (define (process e)
                (cond
                  ((tagged-list? 'import e)
                   (cons (cons (cdr e) (car accum)) (cdr accum)))
                  (else
                    (cons (car accum) (cons e (cdr accum))))))
              (cond
               ((tagged-list? 'cond-expand ex)
                (let ((ex* (expander ex))) ;(expand ex (macro:get-env) rename-env)))
                  ;(trace:info `(DEBUG ,ex* ,ex))
                  (if (tagged-list? 'import ex*)
                      (process ex*)
                      (process ex))))
               (else
                (process ex))))
            (cons '() '())
            expr)))
    (cons
      (apply append (reverse (car results)))
      (reverse (cdr results)))))

;; Return a function to expand any built-in macros
;; NOTE: since this uses a global macro env, it will be overridden later on when
;; macros are loaded from dependent libraries.
(define (base-expander)
  (let ((rename-env (env:extend-environment '() '() '()))
        (macros (filter 
                  (lambda (v) 
                    (Cyc-macro? (Cyc-get-cvar (cdr v))))
                  (Cyc-global-vars))))
    (macro:load-env! macros (create-environment '() '()))
    (lambda (ex) 
      (expand ex (macro:get-env) rename-env))))

;; TODO: longer-term, will be used to find where cyclone's data is installed
(define (get-data-path)
  ".")

(define (get-lib filename)
  (string-append (get-data-path) "/" filename))

(define (read-file filename)
  (call-with-input-file filename
    (lambda (port)
      (read-all port))))

;; Compile and emit:
(define (run-compiler args cc? cc-prog cc-exec cc-lib cc-so append-dirs prepend-dirs)
  (let* ((in-file (car args))
         (expander (base-expander))
         (in-prog-raw (read-file in-file))
         (program? (not (library? (car in-prog-raw))))
         (in-prog
          (if program? 
              in-prog-raw
              ;; Account for any cond-expand declarations in the library
              (list (lib:cond-expand (car in-prog-raw) expander))))
   ;; TODO: expand in-prog, if a library, using lib:cond-expand. (OK, this works now)
   ;; TODO: will also need to do below in lib:get-all-import-deps, after reading each library
         (program:imports/code (if program? (import-reduction in-prog expander) '()))
         (lib-deps 
           (if (and program?
                    (not (null? (car program:imports/code))))
             (lib:get-all-import-deps (car program:imports/code) append-dirs prepend-dirs)
            '()))
         (exec-file (basename in-file))
         (src-file (string-append exec-file ".c"))
         (meta-file (string-append exec-file ".meta"))
         (get-comp-env 
           (lambda (sym str)
             (if (> (string-length str) 0)
                 str
                 (Cyc-compilation-environment sym)))) 
         (create-c-file 
           (lambda (program) 
             (with-output-to-file 
               src-file
               (lambda ()
                 (c-compile-and-emit program program:imports/code 
                                     lib-deps in-file append-dirs prepend-dirs)))))
         (result (create-c-file in-prog)))

    ;; Compile the generated C file
    (cond
      (program?
        (letrec ((objs-str 
                  (apply
                    string-append
                    (map
                      (lambda (i)
                        (string-append " " (lib:import->filename i ".o" append-dirs prepend-dirs) " "))
                      lib-deps)))
                 (comp-prog-cmd 
                   (string-replace-all 
                     (string-replace-all 
                       ;(Cyc-compilation-environment 'cc-prog) 
                       (get-comp-env 'cc-prog cc-prog)
                       "~src-file~" src-file)
                     "~exec-file~" exec-file))
                 (comp-objs-cmd 
                   (string-replace-all
                     (string-replace-all
                       (string-replace-all
                         ;(Cyc-compilation-environment 'cc-exec)
                         (get-comp-env 'cc-exec cc-exec)
                         "~exec-file~" exec-file)
                       "~obj-files~" objs-str)
                     "~exec-file~" exec-file)))
          ;(write `(DEBUG all imports ,lib-deps objs ,objs-str))
          ;(write `(DEBUG ,(lib:get-all-import-deps (cdar in-prog))))
          (cond
            (cc?
             (if (equal? 0 (system comp-prog-cmd))
               (system comp-objs-cmd)))
            (else
              (display comp-prog-cmd)
              (newline)
              (display comp-objs-cmd)
              (newline)))))
      (else
        ;; Emit .meta file
        (with-output-to-file
          meta-file
          (lambda ()
            (display ";; This file was automatically generated by the Cyclone Scheme compiler")
            (newline)
            (write (macro:get-defined-macros))))
        ;; Compile library
        (let ((comp-lib-cmd
                (string-replace-all 
                  (string-replace-all 
                    (get-comp-env 'cc-lib cc-lib)
                    "~src-file~" src-file)
                  "~exec-file~" exec-file))
              (comp-so-cmd
                (string-replace-all 
                  (string-replace-all 
                    (get-comp-env 'cc-so cc-so)
                    "~src-file~" src-file)
                  "~exec-file~" exec-file))
              )
          (cond
            (cc?
              (system comp-lib-cmd)
              (system comp-so-cmd)
            )
            (else
              (display comp-lib-cmd)
              (newline)
              (display comp-so-cmd)
              (newline))))))))

;; Collect values for the given command line arguments and option.
;; Will return a list of values for the option.
;; For example:
;;  ("-a" "1" "2") ==> ("1")
;;  ("-a" "1" -a "2") ==> ("1" "2")
(define (collect-opt-values args opt)
  (cdr
    (foldl
      (lambda (arg accum)
        (cond
          ((equal? arg opt)
           (cons opt (cdr accum)))
          ((car accum) ;; we are at an opt value
           (cons #f (cons arg (cdr accum))))
          (else
           (cons #f (cdr accum)))))
      (list #f)
      args)))

;; Handle command line arguments
(let* ((args (command-line-arguments)) ;; TODO: port (command-line-arguments) to husk??
       (non-opts 
        (if (null? args)
            '()
            (list (car (reverse args)))))
                ; (filter
                ;   (lambda (arg) 
                ;     (not (and (> (string-length arg) 1)
                ;               (equal? #\- (string-ref arg 0)))))
                ;   args))
       (compile? #t)
       (cc-prog (apply string-append (collect-opt-values args "-CP")))
       (cc-exec (apply string-append (collect-opt-values args "-CE")))
       (cc-lib  (apply string-append (collect-opt-values args "-CL")))
       (cc-so   (apply string-append (collect-opt-values args "-CS")))
       (append-dirs (collect-opt-values args "-A"))
       (prepend-dirs (collect-opt-values args "-I")))
  ;; Set optimization level(s)
  (if (member "-O0" args)
      (set! *optimization-level* 0))
  ;; TODO: place more optimization reading here as necessary
  ;; End optimizations
  (if (member "-t" args)
      (set! *trace-level* 4)) ;; Show all trace output
  (if (member "-d" args)
     (set! compile? #f)) ;; Debug, do not run GCC
  (cond
    ((or (member "-h" args)
         (member "--help" args))
     (display "
 -A directory    Append directory to the list of directories that are searched 
                 in order to locate imported libraries.
 -I directory    Prepend directory to the list of directories that are searched 
                 in order to locate imported libraries.
 -CP cc-commands Specify a custom command line for the C compiler to compile
                 a program module. See Makefile.config for an example of how
                 to construct such a command line.
 -CE cc-commands Specify a custom command line for the C compiler to compile
                 an executable.
 -CL cc-commands Specify a custom command line for the C compiler to compile
                 a library module.
 -CS cc-commands Specify a custom command line for the C compiler to compile
                 a shared object module.
 -Ox             Optimization level, higher means more optimizations will
                 be used. Set to 0 to disable optimizations.
 -d              Only generate intermediate C files, do not compile them
 -t              Show intermediate trace output in generated C files
 -h, --help      Display usage information
 -v              Display version information
")
     (newline))
    ((member "-v" args)
     (display *version-banner*))
    ((member "--autogen" args)
     (autogen "autogen.out")
     (newline))
    ((member "-v" args)
     (display *version-banner*))
    ((member "--autogen" args)
     (autogen "autogen.out"))
    ((or (< (length args) 1)
         (null? non-opts))
     (display "cyclone: no input file")
     (newline))
    (else
      (run-compiler non-opts compile? cc-prog cc-exec cc-lib cc-so append-dirs prepend-dirs))))