(.module:
  [lux #- not or and list if function cond when]
  (lux (control pipe)
       (data [maybe "maybe/" Functor<Maybe>]
             [text]
             text/format
             [number]
             (coll [list "list/" Functor<List> Fold<List>]))
       (type abstract)))

(abstract: #export Single {} Top)
(abstract: #export Poly {} Top)

(abstract: #export (Var kind)
  {}

  Text

  (def: name (All [k] (-> (Var k) Text)) (|>> @representation))

  (def: #export var (-> Text (Var Single)) (|>> @abstraction))
  (def: #export var-args (Var Poly) (@abstraction "..."))
  )

(type: #export SVar (Var Single))
(type: #export PVar (Var Poly))

(abstract: #export Expression
  {}
  
  Text

  (def: #export expression (-> Expression Text) (|>> @representation))

  (def: #export code (-> Text Expression) (|>> @abstraction))

  (def: (self-contained code)
    (-> Text Expression)
    (@abstraction
     (format "(" code ")")))

  (def: nest
    (-> Text Text)
    (|>> (format "\n")
         (text.replace-all "\n" "\n  ")))

  (def: (_block expression)
    (-> Text Text)
    (format "{" (nest expression) "\n" "}"))

  (def: #export (block expression)
    (-> Expression Expression)
    (@abstraction
     (format "{" (@representation expression) "}")))

  (def: #export null
    Expression
    (|> "NULL" self-contained))

  (def: #export n/a
    Expression
    (|> "NA" self-contained))

  (def: #export not-available Expression n/a)
  (def: #export not-applicable Expression n/a)
  (def: #export no-answer Expression n/a)

  (def: #export bool
    (-> Bool Expression)
    (|>> (case> true "TRUE"
                false "FALSE")
         self-contained))

  (def: #export (int value)
    (-> Int Expression)
    (self-contained
     (format "as.integer(" (%i value) ")")))

  (def: #export float
    (-> Frac Expression)
    (|>> (cond> [(f/= number.positive-infinity)]
                [(new> "1.0/0.0")]
                
                [(f/= number.negative-infinity)]
                [(new> "-1.0/0.0")]
                
                [(f/= number.not-a-number)]
                [(new> "0.0/0.0")]
                
                ## else
                [%f])
         self-contained))

  (def: #export string
    (-> Text Expression)
    (|>> %t self-contained))

  (def: (composite-literal left-delimiter right-delimiter entry-serializer)
    (All [a] (-> Text Text (-> a Text)
                 (-> (List a) Expression)))
    (.function (_ entries)
      (self-contained
       (format left-delimiter
               (|> entries (list/map entry-serializer) (text.join-with ","))
               right-delimiter))))

  (def: #export named-list
    (-> (List [Text Expression]) Expression)
    (composite-literal "list(" ")" (.function (_ [key value])
                                     (format key "=" (@representation value)))))
  
  (do-template [<name> <function>]
    [(def: #export <name>
       (-> (List Expression) Expression)
       (composite-literal (format <function> "(") ")" expression))]

    [vector "c"]
    [list   "list"]
    )
  
  (def: #export (slice from to list)
    (-> Expression Expression Expression Expression)
    (self-contained
     (format (@representation list)
             "[" (@representation from) ":" (@representation to) "]")))

  (def: #export (slice-from from list)
    (-> Expression Expression Expression)
    (self-contained
     (format (@representation list)
             "[-1"  ":-" (@representation from) "]")))

  (def: #export (apply args func)
    (-> (List Expression) Expression Expression)
    (self-contained
     (format (@representation func) "(" (text.join-with "," (list/map expression args)) ")")))

  (def: #export (apply-kw args kw-args func)
    (-> (List Expression) (List [Text Expression]) Expression Expression)
    (self-contained
     (format (@representation func)
             (format "("
                     (text.join-with "," (list/map expression args)) ","
                     (text.join-with "," (list/map (.function (_ [key val])
                                                     (format key "=" (expression val)))
                                                   kw-args))
                     ")"))))

  (def: #export (nth idx list)
    (-> Expression Expression Expression)
    (self-contained
     (format (@representation list) "[[" (@representation idx) "]]")))

  (def: #export (if test then else)
    (-> Expression Expression Expression Expression)
    (self-contained
     (format "if(" (@representation test) ")"
             " " (.._block (@representation then))
             " else " (.._block (@representation else)))))

  (def: #export (when test then)
    (-> Expression Expression Expression)
    (self-contained
     (format "if(" (@representation test) ") {"
             (.._block (@representation then))
             "\n" "}")))

  (def: #export (cond clauses else)
    (-> (List [Expression Expression]) Expression Expression)
    (list/fold (.function (_ [test then] next)
                 (if test then next))
               else
               (list.reverse clauses)))

  (do-template [<name> <op>]
    [(def: #export (<name> param subject)
       (-> Expression Expression Expression)
       (self-contained
        (format (@representation subject)
                " " <op> " "
                (@representation param))))]

    [=       "=="]
    [<       "<"]
    [<=      "<="]
    [>       ">"]
    [>=      ">="]
    [+       "+"]
    [-       "-"]
    [*       "*"]
    [/       "/"]
    [%%      "%%"]
    [**      "**"]
    [or      "||"]
    [and     "&&"]
    )

  (def: #export @@
    (All [k] (-> (Var k) Expression))
    (|>> ..name self-contained))

  (def: #export global
    (-> Text Expression)
    (|>> var @@))

  (do-template [<name> <func>]
    [(def: #export (<name> param subject)
       (-> Expression Expression Expression)
       (..apply (.list subject param) (..global <func>)))]

    [bit-or   "bitwOr"]
    [bit-and  "bitwAnd"]
    [bit-xor  "bitwXor"]
    [bit-shl  "bitwShiftL"]
    [bit-ushr "bitwShiftR"]
    )

  (def: #export (bit-not subject)
    (-> Expression Expression)
    (..apply (.list subject) (..global "bitwNot")))

  (do-template [<name> <op>]
    [(def: #export <name>
       (-> Expression Expression)
       (|>> @representation (format <op>) self-contained))]

    [not    "!"]
    [negate "-"]
    )
  
  (def: #export (length list)
    (-> Expression Expression)
    (..apply (.list list) (..global "length")))

  (def: #export (range from to)
    (-> Expression Expression Expression)
    (self-contained
     (format (@representation from) ":" (@representation to))))

  (def: #export (function inputs body)
    (-> (List (Ex [k] (Var k))) Expression Expression)
    (let [args (|> inputs (list/map ..name) (text.join-with ", "))]
      (self-contained
       (format "function(" args ") "
               (.._block (@representation body))))))

  (def: #export (try body warning error finally)
    (-> Expression (Maybe Expression) (Maybe Expression) (Maybe Expression) Expression)
    (let [optional (: (-> Text (Maybe Expression) (-> Text Text) Text)
                      (.function (_ parameter value preparation)
                        (|> value
                            (maybe/map (|>> @representation preparation (format ", " parameter " = ")))
                            (maybe.default ""))))]
      (self-contained
       (format "tryCatch("
               (.._block (@representation body))
               (optional "warning" warning id)
               (optional "error" error id)
               (optional "finally" finally .._block)
               ")"))))

  (def: #export (while test body)
    (-> Expression Expression Expression)
    (self-contained
     (format "while (" (@representation test) ") "
             (.._block (@representation body)))))

  (def: #export (for-in var inputs body)
    (-> SVar Expression Expression Expression)
    (self-contained
     (format "for (" (..name var) " in " (..expression inputs) ")"
             (.._block (@representation body)))))

  (do-template [<name> <keyword>]
    [(def: #export (<name> message)
       (-> Expression Expression)
       (..apply (.list message) (..global <keyword>)))]

    [stop  "stop"]
    [print "print"]
    )

  (def: #export (set! var value)
    (-> (Var Single) Expression Expression)
    (self-contained
     (format (..name var) " <- " (@representation value))))

  (def: #export (set-nth! idx value list)
    (-> Expression Expression SVar Expression)
    (self-contained
     (format (..name list) "[[" (@representation idx) "]] <- " (@representation value))))

  (def: #export (then pre post)
    (-> Expression Expression Expression)
    (@abstraction
     (format (@representation pre)
             "\n"
             (@representation post))))
  )