(.module:
  [lux (#- inc)
   [abstract
    [monad (#+ do)]]
   [control
    ["." function]
    ["p" parser
     ["s" code]]]
   [data
    [number (#+ hex)
     ["." i64]]
    ["." text
     format]
    [collection
     ["." list ("#@." functor)]]]
   ["." macro
    ["." code]
    [syntax (#+ syntax:)]]
   [target
    ["_" common-lisp (#+ Expression Var/1 Computation Literal)]]]
  ["." ///
   ["//." //
    [//
     ["/////." name]
     ["." synthesis]]]]
  )

(template [<name> <base>]
  [(type: #export <name>
     (<base> Var/1 (Expression Any) (Expression Any)))]

  [Operation ///.Operation]
  [Phase ///.Phase]
  [Handler ///.Handler]
  [Bundle ///.Bundle]
  )

(def: prefix "LuxRuntime")

(def: #export unit (_.string synthesis.unit))

(def: (flag value)
  (-> Bit Literal)
  (if value
    (_.string "")
    _.nil))

(def: (variant' tag last? value)
  (-> (Expression Any) (Expression Any) (Expression Any) (Computation Any))
  (_.list/* (list tag last? value)))

(def: #export (variant tag last? value)
  (-> Nat Bit (Expression Any) (Computation Any))
  (variant' (_.int (.int tag))
            (flag last?)
            value))

(def: #export none
  (Computation Any)
  (..variant 0 false ..unit))

(def: #export some
  (-> (Expression Any) (Computation Any))
  (..variant 1 true))

(def: #export left
  (-> (Expression Any) (Computation Any))
  (..variant 0 false))

(def: #export right
  (-> (Expression Any) (Computation Any))
  (..variant 1 true))

(def: runtime-name
  (-> Text Var/1)
  (|>> /////name.normalize
       (format ..prefix "_")
       _.var))

(def: (feature name definition)
  (-> Var/1 (-> Var/1 (Expression Any)) (Expression Any))
  (definition name))

(syntax: #export (with-vars {vars (s.tuple (p.some s.local-identifier))}
                   body)
  (wrap (list (` (let [(~+ (|> vars
                               (list@map (function (_ var)
                                           (list (code.local-identifier var)
                                                 (` (_.var (~ (code.text (/////name.normalize var))))))))
                               list.concat))]
                   (~ body))))))

(syntax: (runtime: {declaration (p.or s.local-identifier
                                      (s.form (p.and s.local-identifier
                                                     (p.some s.local-identifier))))}
           code)
  (macro.with-gensyms [g!_ g!L]
    (case declaration
      (#.Left name)
      (let [code-nameC (code.local-identifier (format "@" name))
            runtime-nameC (` (runtime-name (~ (code.text name))))]
        (wrap (list (` (def: #export (~ (code.local-identifier name)) _.Var/1 (~ runtime-nameC)))
                    (` (def: (~ code-nameC)
                         (_.Expression Any)
                         (..feature (~ runtime-nameC)
                                    (function ((~ g!_) (~ g!L))
                                      (_.defparameter (~ g!L) (~ code)))))))))
      
      (#.Right [name inputs])
      (let [code-nameC (code.local-identifier (format "@" name))
            runtime-nameC (` (runtime-name (~ (code.text name))))
            inputsC (list@map code.local-identifier inputs)
            inputs-typesC (list@map (function.constant (` (_.Expression Any)))
                                    inputs)]
        (wrap (list (` (def: #export ((~ (code.local-identifier name)) (~+ inputsC))
                         (-> (~+ inputs-typesC) (_.Computation Any))
                         (_.call/* (~ runtime-nameC) (list (~+ inputsC)))))
                    (` (def: (~ code-nameC)
                         (_.Expression Any)
                         (..feature (~ runtime-nameC)
                                    (function ((~ g!_) (~ g!L))
                                      (..with-vars [(~+ inputsC)]
                                        (_.defun (~ g!L) (_.args (list (~+ inputsC)))
                                                 (~ code)))))))))))))

(runtime: (lux//try op)
  (with-vars [error]
    (_.handler-case
     (list [(_.bool true) error
            (..left (_.format/3 [_.nil (_.string "~A") error]))])
     (..right (_.funcall/+ [op (list ..unit)])))))

## TODO: Use Common Lisp's swiss-army loop macro instead.
(runtime: (lux//program-args inputs)
  (with-vars [loop input tail]
    (_.labels (list [loop [(_.args (list input tail))
                           (_.if (_.null/1 input)
                             tail
                             (_.funcall/+ [(_.function/1 loop)
                                           (list (_.cdr/1 input)
                                                 (..some (_.vector/* (list (_.car/1 input) tail))))]))]])
              (_.funcall/+ [(_.function/1 loop)
                            (list (_.reverse/1 inputs)
                                  ..none)]))))

(def: runtime//lux
  ($_ _.progn
      @lux//try
      @lux//program-args))

(def: last-index
  (|>> _.length/1 (_.- (_.int +1))))

(with-expansions [<recur> (as-is ($_ _.then
                                     (_.; (_.set lefts (_.- last-index-right lefts)))
                                     (_.; (_.set tuple (_.nth last-index-right tuple)))))]
  (template: (!recur <side>)
    (<side> (|> lefts (_.- last-index-right))
            (_.elt/2 [tuple last-index-right])))
  
  (runtime: (tuple//left lefts tuple)
    (with-vars [last-index-right]
      (_.let (list [last-index-right (..last-index tuple)])
        (_.if (_.> lefts last-index-right)
          ## No need for recursion
          (_.elt/2 [tuple lefts])
          ## Needs recursion
          (!recur tuple//left)))))

  (runtime: (tuple//right lefts tuple)
    (with-vars [last-index-right right-index]
      (_.let (list [last-index-right (..last-index tuple)]
                   [right-index (_.+ (_.int +1) lefts)])
        (_.cond (list [(_.= last-index-right right-index)
                       (_.elt/2 [tuple right-index])]
                      [(_.> last-index-right right-index)
                       ## Needs recursion.
                       (!recur tuple//right)])
                (_.subseq/3 [tuple right-index (_.length/1 tuple)]))
        ))))

## TODO: Find a way to extract parts of the sum without "nth", which
## does a linear search, and is thus expensive.
(runtime: (sum//get sum wantsLast wantedTag)
  (with-vars [sum-tag sum-flag]
    (let [@exit (_.label "exit")
          return! (_.return-from @exit)
          no-match! (return! sum)
          sum-value (_.nth/2 [(_.int +2) sum])
          test-recursion! (_.if sum-flag
                            ## Must iterate.
                            ($_ _.progn
                                (_.setq sum sum-value)
                                (_.setq wantedTag (_.- sum-tag wantedTag)))
                            no-match!)]
      (<| (_.progn (_.setq sum-tag (_.nth/2 [(_.int +0) sum])))
          (_.progn (_.setq sum-flag (_.nth/2 [(_.int +1) sum])))
          (_.block @exit)
          (_.while (_.bool true))
          (_.cond (list [(_.= sum-tag wantedTag)
                         (_.if (_.equal wantsLast sum-flag)
                           (return! sum-value)
                           test-recursion!)]

                        [(_.> sum-tag wantedTag)
                         test-recursion!]

                        [(_.and (_.< sum-tag wantedTag)
                                wantsLast)
                         (return! (variant' (_.- wantedTag sum-tag) sum-flag sum-value))])

                  no-match!)))))

(def: runtime//adt
  ($_ _.progn
      @tuple//left
      @tuple//right
      @sum//get))

(runtime: (i64//logic-right-shift shift input)
  (_.if (_.= (_.int +0) shift)
    input
    (|> input
        (_.ash (_.* (_.int -1) shift))
        (_.logand (_.int (hex "+7FFFFFFFFFFFFFFF"))))))

(def: runtime//i64
  ($_ _.progn
      @i64//logic-right-shift))

(runtime: (text//clip from to text)
  (_.subseq/3 [text from to]))

(runtime: (text//index reference start space)
  (with-vars [index]
    (_.let (list [index (_.search/3 [reference space start])])
      (_.if index
        (..some index)
        ..none))))

(def: runtime//text
  ($_ _.progn
      @text//index
      @text//clip))

(runtime: (io//exit code)
  ($_ _.progn
      (_.conditional+ (list "sbcl")
                      (_.call/* (_.var "sb-ext:quit") (list code)))
      (_.conditional+ (list "clisp")
                      (_.call/* (_.var "ext:exit") (list code)))
      (_.conditional+ (list "ccl")
                      (_.call/* (_.var "ccl:quit") (list code)))
      (_.conditional+ (list "allegro")
                      (_.call/* (_.var "excl:exit") (list code)))
      (_.call/* (_.var "cl-user::quit") (list code))))

(runtime: (io//current-time _)
  (|> (_.get-universal-time/0 [])
      (_.* (_.int +1,000))))

(def: runtime//io
  ($_ _.progn
      @io//exit
      @io//current-time))

(def: runtime
  ($_ _.progn
      runtime//adt
      runtime//lux
      runtime//i64
      runtime//text
      runtime//io))

(def: #export artifact ..prefix)

(def: #export generate
  (Operation Any)
  (///.with-buffer
    (do ////.monad
      [_ (///.save! true ["" ..prefix]
                    ..runtime)]
      (///.save-buffer! ..artifact))))