(.module:
  [lux (#- if let case)
   [control
    [monad (#+ do)]
    ["ex" exception (#+ exception:)]]
   [data
    [text
     format]]
   [compiler
    [default
     ["." phase ("operation/." Monad<Operation>)
      ["." synthesis (#+ Path Synthesis)]]]]]
  [luxc
   [lang
    [host
     ["$" jvm (#+ Label Inst Operation Phase)
      ["$t" type]
      ["_" inst]]]]]
  ["." // (#+ $Object)
   ["." runtime]])

(def: (pop-altI stack-depth)
  (-> Nat Inst)
  (.case stack-depth
    0 id
    1 _.POP
    2 _.POP2
    _ ## (n/> 2)
    (|>> _.POP2
         (pop-altI (n/- 2 stack-depth)))))

(def: peekI
  Inst
  (|>> _.DUP
       (_.INVOKESTATIC //.runtime-class
                       "pm_peek"
                       ($t.method (list runtime.$Stack)
                                  (#.Some $Object)
                                  (list))
                       #0)))

(def: popI
  Inst
  (|>> (_.INVOKESTATIC //.runtime-class
                       "pm_pop"
                       ($t.method (list runtime.$Stack)
                                  (#.Some runtime.$Stack)
                                  (list))
                       #0)))

(def: pushI
  Inst
  (|>> (_.INVOKESTATIC //.runtime-class
                       "pm_push"
                       ($t.method (list runtime.$Stack $Object)
                                  (#.Some runtime.$Stack)
                                  (list))
                       #0)))

(def: (path' translate stack-depth @else @end path)
  (-> (-> Synthesis (Operation Inst))
      Nat Label Label Path (Operation Inst))
  (.case path
    #synthesis.Pop
    (operation/wrap popI)
    
    (#synthesis.Bind register)
    (operation/wrap (|>> peekI
                         (_.ASTORE register)))

    (^ (synthesis.path/bit value))
    (operation/wrap (.let [jumpI (.if value _.IFEQ _.IFNE)]
                      (|>> peekI
                           (_.unwrap #$.Boolean)
                           (jumpI @else))))
    
    (^ (synthesis.path/i64 value))
    (operation/wrap (|>> peekI
                         (_.unwrap #$.Long)
                         (_.long (.int value))
                         _.LCMP
                         (_.IFNE @else)))
    
    (^ (synthesis.path/f64 value))
    (operation/wrap (|>> peekI
                         (_.unwrap #$.Double)
                         (_.double value)
                         _.DCMPL
                         (_.IFNE @else)))
    
    (^ (synthesis.path/text value))
    (operation/wrap (|>> peekI
                         (_.string value)
                         (_.INVOKEVIRTUAL "java.lang.Object"
                                          "equals"
                                          ($t.method (list $Object)
                                                     (#.Some $t.boolean)
                                                     (list))
                                          #0)
                         (_.IFEQ @else)))
    
    (#synthesis.Then bodyS)
    (do phase.Monad<Operation>
      [bodyI (translate bodyS)]
      (wrap (|>> (pop-altI stack-depth)
                 bodyI
                 (_.GOTO @end))))
    
    
    (^template [<pattern> <method> <mod>]
      (^ (<pattern> idx))
      (operation/wrap (.case (<mod> idx)
                        0
                        (|>> peekI
                             (_.CHECKCAST ($t.descriptor runtime.$Tuple))
                             (_.int +0)
                             _.AALOAD
                             pushI)
                        
                        idx
                        (|>> peekI
                             (_.CHECKCAST ($t.descriptor runtime.$Tuple))
                             (_.int (.int idx))
                             (_.INVOKESTATIC //.runtime-class
                                             <method>
                                             ($t.method (list runtime.$Tuple $t.int)
                                                        (#.Some $Object)
                                                        (list))
                                             #0)
                             pushI))))
    ([synthesis.member/left  "pm_left"  .id]
     [synthesis.member/right "pm_right" .inc])

    (^template [<pattern> <flag> <mod>]
      (^ (<pattern> idx))
      (.let [idx (<mod> idx)]
        (operation/wrap (<| _.with-label (function (_ @success))
                            _.with-label (function (_ @fail))
                            (|>> peekI
                                 (_.CHECKCAST ($t.descriptor runtime.$Variant))
                                 (_.int (.int idx))
                                 <flag>
                                 (_.INVOKESTATIC //.runtime-class "pm_variant"
                                                 ($t.method (list runtime.$Variant runtime.$Tag runtime.$Flag)
                                                            (#.Some runtime.$Datum)
                                                            (list))
                                                 #0)
                                 _.DUP
                                 (_.IFNULL @fail)
                                 (_.GOTO @success)
                                 (_.label @fail)
                                 _.POP
                                 (_.GOTO @else)
                                 (_.label @success)
                                 pushI)))))
    ([synthesis.side/left  _.NULL        .id]
     [synthesis.side/right (_.string "") .inc])

    (#synthesis.Alt leftP rightP)
    (do phase.Monad<Operation>
      [@alt-else _.make-label
       leftI (path' translate (inc stack-depth) @alt-else @end leftP)
       rightI (path' translate stack-depth @else @end rightP)]
      (wrap (|>> _.DUP
                 leftI
                 (_.label @alt-else)
                 _.POP
                 rightI)))
    
    (#synthesis.Seq leftP rightP)
    (do phase.Monad<Operation>
      [leftI (path' translate stack-depth @else @end leftP)
       rightI (path' translate stack-depth @else @end rightP)]
      (wrap (|>> leftI
                 rightI)))
    ))

(def: (path translate path @end)
  (-> Phase Path Label (Operation Inst))
  (do phase.Monad<Operation>
    [@else _.make-label
     pathI (..path' translate 1 @else @end path)]
    (wrap (|>> pathI
               (_.label @else)
               _.POP
               (_.INVOKESTATIC //.runtime-class
                               "pm_fail"
                               ($t.method (list) #.None (list))
                               #0)
               _.NULL
               (_.GOTO @end)))))

(def: #export (if translate testS thenS elseS)
  (-> Phase Synthesis Synthesis Synthesis (Operation Inst))
  (do phase.Monad<Operation>
    [testI (translate testS)
     thenI (translate thenS)
     elseI (translate elseS)]
    (wrap (<| _.with-label (function (_ @else))
              _.with-label (function (_ @end))
              (|>> testI
                   (_.unwrap #$.Boolean)
                   (_.IFEQ @else)
                   thenI
                   (_.GOTO @end)
                   (_.label @else)
                   elseI
                   (_.label @end))))))

(def: #export (let translate inputS register exprS)
  (-> Phase Synthesis Nat Synthesis (Operation Inst))
  (do phase.Monad<Operation>
    [inputI (translate inputS)
     exprI (translate exprS)]
    (wrap (|>> inputI
               (_.ASTORE register)
               exprI))))

(def: #export (case translate valueS path)
  (-> Phase Synthesis Path (Operation Inst))
  (do phase.Monad<Operation>
    [@end _.make-label
     valueI (translate valueS)
     pathI (..path translate path @end)]
    (wrap (|>> valueI
               _.NULL
               _.SWAP
               pushI
               pathI
               (_.label @end)))))