... This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
... If a copy of the MPL was not distributed with this file, You can obtain one at https://mozilla.org/MPL/2.0/.

(.require
 [library
  [lux (.except Global #Local #location with local global)
   [abstract
    [monad (.only do)]]
   [control
    ["?" parser]
    ["[0]" maybe]
    [function
     [predicate (.only Predicate)]]]
   [data
    ["[0]" text (.use "[1]#[0]" equivalence)
     ["%" \\format]]
    [collection
     ["[0]" list (.use "[1]#[0]" mix)
      ["[0]" property]]]]
   ["[0]" meta (.only)
    [extension (.only analysis declaration)]
    ["[0]" code (.only)
     ["?[1]" \\parser]]
    ["[0]" macro (.only)
     [syntax (.only syntax)]
     ["^" pattern]]
    [type
     ["[0]" check]]
    [compiler
     [language
      [lux
       ["[0]" phase]
       ["[0]" declaration]
       ["[0]" analysis (.only)
        ["[0]" module]
        ["[0]" type]]]]]]]])

(type .public (Advice value)
  (-> value value))

(def .public (before pre)
  (All (_ input output)
    (-> (-> input input)
        (Advice (-> input output))))
  (function (_ it input)
    (it (pre input))))

(type .public (Reference name)
  (Record
   [#name name
    #type Type]))

(type .public Local
  (Reference Text))

(type .public Global
  (Reference Symbol))

(type .public Scenario
  (Variant
   {#Local Local}
   {#Global Global}))

(type .public Join_Point
  (Record
   [#location Location
    #scenario Scenario]))

(type .public Point_Cut
  (Predicate Join_Point))

(def .public (when_module ?)
  (-> (Predicate Text)
      Point_Cut)
  (|>> (the [#location .#module])
       ?))

(with_template [<type> <tag> <name>]
  [(def .public (<name> ?)
     (-> (Predicate <type>)
         Point_Cut)
     (function (_ it)
       (when (the #scenario it)
         {<tag> it}
         (? it)

         _
         false)))]

  [Local #Local when_local]
  [Global #Global when_global]
  )

(def .public (typed? expected)
  (-> Type
      Point_Cut)
  (function (_ it)
    (when (the #scenario it)
      (^.or {#Local [_ it]}
            {#Global [_ it]})
      (check.subsumes? expected it))))

(type .public Aspect
  (List [Point_Cut Symbol]))

(def (without_global [module short])
  (-> Symbol (analysis.Operation Any))
  (function (_ lux)
    (let [without_global (is (-> (property.List [Bit .Global]) (property.List [Bit .Global]))
                             (property.lacks short))
          without_global (is (-> .Module .Module)
                             (revised .#definitions without_global))
          without_global (is (-> (property.List .Module) (property.List .Module))
                             (property.revised module without_global))
          without_global (is (-> Lux Lux)
                             (revised .#modules without_global))]
      {.#Right [(without_global lux)
                []]})))

(def (global_reference name)
  (-> Symbol (Meta [Bit .Global]))
  (do meta.monad
    [name (meta.normal name)
     current_module_name meta.current_module_name
     lux meta.compiler_state]
    (loop (again [[normal_module normal_short] name])
      (when (is (Maybe [Bit .Global])
                (do maybe.monad
                  [(open "/[0]") (|> lux
                                     (the .#modules)
                                     (property.value normal_module))]
                  (property.value normal_short /#definitions)))
        {.#Some [exported? it]}
        (when it
          {.#Definition [type value]}
          (if (or exported?
                  (text#= current_module_name normal_module))
            (in [exported? it])
            (meta.failure (%.format "Global is not an export: " (%.symbol name))))

          {.#Default [type value]}
          (if (or exported?
                  (text#= current_module_name normal_module))
            (in [exported? it])
            (meta.failure (%.format "Global is not an export: " (%.symbol name))))

          {.#Alias de_aliased}
          (again de_aliased))

        {.#None it}
        (meta.failure (%.format "Unknown global: " (%.symbol name)))))))

(def (with_cached_analysis name then)
  (All (_ of)
    (-> Symbol (-> [Code .Global] (analysis.Operation of))
        (analysis.Operation of)))
  (do phase.monad
    [g!cache (macro.symbol "g!cache")
     [exported? global] (global_reference name)
     .let [cache_name (%.code g!cache)]
     _ (module.define cache_name [exported? global])
     it (then [g!cache global])
     current_module_name meta.current_module_name
     _ (without_global [current_module_name cache_name])]
    (in it)))

(def (with_cached_analysis' name then)
  (All (_ anchor expression declaration of)
    (-> Symbol (-> [Code .Global] (declaration.Operation anchor expression declaration of))
        (declaration.Operation anchor expression declaration of)))
  (do phase.monad
    [g!cache (declaration.of_analysis
              (macro.symbol "g!cache"))
     [exported? global] (declaration.of_analysis
                         (global_reference name))
     .let [cache_name (%.code g!cache)]
     _ (declaration.of_analysis
        (module.define cache_name [exported? global]))
     it (then [g!cache global])
     current_module_name (declaration.of_analysis
                          meta.current_module_name)
     _ (declaration.of_analysis
        (without_global [current_module_name cache_name]))]
    (in it)))

(def (with_temporary_global [name new] then)
  (All (_ of)
    (-> [Symbol .Global] (analysis.Operation of)
        (analysis.Operation of)))
  (do phase.monad
    [[exported? old] (global_reference name)
     _ (module.override_definition name [exported? new])
     it then
     _ (module.override_definition name [exported? old])]
    (in it)))

(def (with_temporary_global' [name new] then)
  (All (_ anchor expression declaration of)
    (-> [Symbol .Global] (declaration.Operation anchor expression declaration of)
        (declaration.Operation anchor expression declaration of)))
  (do phase.monad
    [[exported? old] (declaration.of_analysis
                      (global_reference name))
     _ (declaration.of_analysis
        (module.override_definition name [exported? new]))
     it then
     _ (declaration.of_analysis
        (module.override_definition name [exported? old]))]
    (in it)))

(def (expression type term)
  (-> Type analysis.Analysis Analysis)
  (analysis (_ phase archive [])
    (do phase.monad
      [_ (type.inference type)]
      (in term))))

(def (with_cached_expression [type term] then)
  (All (_ of)
    (-> [Type analysis.Analysis]
        (-> (-> Code (analysis.Operation of))
            (analysis.Operation of))))
  (do phase.monad
    [g!cache (macro.symbol "g!cache")
     .let [cache_name (%.code g!cache)]
     _ (module.define cache_name [false {.#Definition [Analysis (expression type term)]}])
     it (then g!cache)
     current_module_name meta.current_module_name
     _ (without_global [current_module_name cache_name])]
    (in it)))

(with_template [<name> <parameters> <term> <scenario> <advised>]
  [(def (<name> original aspect)
     (-> Code Aspect Analysis)
     (analysis (_ phase archive <parameters>)
       (do [! phase.monad]
         [[type term] (type.inferring
                       (phase archive <term>))
          _ (type.inference type)
          location meta.location
          .let [join_point [#location location
                            #scenario {<scenario> [it type]}]]]
         (when (list.one (function (_ [point_cut advice])
                           (if (point_cut join_point)
                             {.#Some advice}
                             {.#None}))
                         aspect)
           {.#Some advice}
           (<| (with_cached_expression [type term])
               (function (_ analysis))
               (phase archive <advised>))
           
           {.#None}
           (in term)))))]

  [local [it ?code.local]
   (` ((, original) (, (code.local it))))
   #Local
   (` ((, (code.symbol advice)) ((, analysis))))]
  [global [quoted_module ?code.any
           it ?code.global]
   (` ((, original) (, quoted_module) (, (code.symbol it))))
   #Global
   (let [[advice_module _] advice]
     (` (((, original) (, (code.text advice_module)) (, (code.symbol advice)))
         ((, analysis)))))]
  )

(def with|analysis
  Analysis
  (analysis (_ phase archive [aspect ?code.any
                              body ?code.any])
    (do [! phase.monad]
      [aspect (meta.eval Aspect aspect)
       .let [aspect (as Aspect aspect)]]
      (list#mix (function (_ [original value] then)
                  (<| (with_cached_analysis original)
                      (function (_ [g!original original_global]))
                      (with_temporary_global [original {.#Definition [Analysis (value g!original aspect)]}])
                      then))
                (phase archive body)
                (list [(symbol .local#) ..local]
                      [(symbol .global#) ..global])))))

(def with|declaration
  Declaration
  (declaration (_ phase archive [aspect ?code.any
                                 body ?code.any])
    (do [! phase.monad]
      [aspect (declaration.of_analysis
               (meta.eval Aspect aspect))
       .let [aspect (as Aspect aspect)]]
      (list#mix (function (_ [original value] then)
                  (<| (with_cached_analysis' original)
                      (function (_ [g!original original_global]))
                      (with_temporary_global' [original {.#Definition [Analysis (value g!original aspect)]}])
                      then))
                (phase archive body)
                (list [(symbol .local#) ..local]
                      [(symbol .global#) ..global])))))

(def expression?
  (Meta Bit)
  (function (_ lux)
    {.#Right [lux
              (when (the .#expected lux)
                {.#Some _} true
                {.#None _} false)]}))

(def .public with
  (syntax (_ [aspect ?code.any
              body ?code.any])
    (do meta.monad
      [? ..expression?
       .let [[@ _] (symbol .._)
             <with> (if ?
                      (` ..with|analysis)
                      (` ..with|declaration))]]
      (in (list (` ((.in_module# (, (code.text @)) (, <with>))
                    (, aspect)
                    (, body))))))))