(.module:
  [lux #*
   [abstract
    ["." monad (#+ do)]]
   [control
    [pipe (#+ when>)]
    ["ex" exception (#+ exception:)]
    [security
     ["!" capability]]]
   [cli (#+ program:)]
   [data
    ["." maybe]
    ["." product]
    ["." error (#+ Error)]
    [format
     ["md" markdown (#+ Markdown Span Block)]]
    ["." text ("#;." equivalence)
     ["%" format (#+ format)]
     ["." encoding]]
    [collection
     ["." sequence (#+ Sequence) ("#;." functor)]
     ["." list ("#;." functor fold)]]]
   ["." function]
   ["." type ("#@." equivalence)]
   ["." macro]
   ["." io (#+ IO io)]
   [world
    ["." file (#+ File)]]]
  ## This was added to make sure that all tested modules are picked up
  ## and their documentation is generated.
  [test/lux (#+)])

(def: name-options "abcdefghijklmnopqrstuvwxyz")
(def: name-options-count (text.size name-options))

(def: (parameter-type-name id)
  (-> Nat Text)
  (case (text.nth id ..name-options)
    (#.Some char)
    (text.from-code char)

    #.None
    (format (parameter-type-name (n// name-options-count id))
            (parameter-type-name (n/% name-options-count id)))))

(def: type-var-names
  (Sequence Text)
  (|> 0 (sequence.iterate inc) (sequence;map parameter-type-name)))

(template [<name> <partition>]
  [(def: (<name> id)
     (-> Nat Bit)
     (<partition> id))]

  [type-func? n/even?]
  [type-arg? n/odd?]
  )

(def: (arg-id level id)
  (-> Nat Nat Nat)
  (n/- (n// 2 id) level))

(def: (parameter->name [type-func-name type-function-arguments] level id)
  (-> [Text (List Text)] Nat Nat Text)
  (if (type-arg? id)
    (let [arg-id (..arg-id level id)]
      (case (list.nth arg-id type-function-arguments)
        (#.Some found)
        found

        _
        (|> type-var-names
            (sequence.filter (function (_ var-name)
                               (not (list.member? text.equivalence type-function-arguments var-name))))
            (sequence.nth arg-id))))      
    type-func-name))

(def: (level->args offset level)
  (-> Nat Nat (List Text))
  (if (n/= 0 level)
    (list)
    (|> level
        dec
        (list.n/range 0)
        (list;map (|>> (n/+ (inc offset)) parameter-type-name)))))

(def: (prefix-lines prefix lines)
  (-> Text Text Text)
  (|> lines
      (text.split-all-with text.new-line)
      (list;map (|>> (format prefix)))
      (text.join-with text.new-line)))

(def: (pprint-type-definition level type-func-info tags module signature? recursive-type? type)
  (-> Nat [Text (List Text)] (List Name) Text Bit Bit Type Text)
  (case tags
    (^ (list [_ single-tag]))
    (if signature?
      (format "(: " (pprint-type-definition level type-func-info #.None module signature? recursive-type? type) text.new-line "   " single-tag ")")
      (format "{#" single-tag " " (pprint-type-definition level type-func-info #.None module signature? recursive-type? type) "}"))

    _
    (case [recursive-type? type]
      [_ (#.Primitive name params)]
      (case params
        #.Nil
        (format "(primitive " (%.text name) ")")

        _
        (format "(primitive " (%.text name) " " (|> params (list;map (pprint-type-definition level type-func-info #.None module signature? recursive-type?)) (text.join-with " ")) ")"))

      [_ (#.Sum _)]
      (let [members (type.flatten-variant type)]
        (case tags
          #.Nil
          (format "(| "
                  (|> members
                      (list;map (pprint-type-definition level type-func-info #.None module signature? recursive-type?))
                      (text.join-with " "))
                  ")")

          _
          (|> members
              (list.zip2 tags)
              (list;map (function (_ [[_ t-name] type])
                          (case type
                            (#.Product _)
                            (let [types (type.flatten-tuple type)]
                              (format "(#" t-name " "
                                      (|> types
                                          (list;map (pprint-type-definition level type-func-info #.None module signature? recursive-type?))
                                          (text.join-with " "))
                                      ")"))

                            _
                            (format "(#" t-name " " (pprint-type-definition level type-func-info #.None module signature? recursive-type? type) ")"))))
              (text.join-with text.new-line))))

      [_ (#.Product _)]
      (let [members (type.flatten-tuple type)]
        (case tags
          #.Nil
          (format "[" (|> members (list;map (pprint-type-definition level type-func-info #.None module signature? recursive-type?)) (text.join-with " ")) "]")

          _
          (let [member-docs (|> members
                                (list.zip2 tags)
                                (list;map (function (_ [[_ t-name] type])
                                            (if signature?
                                              (format "(: " (pprint-type-definition level type-func-info #.None module signature? recursive-type? type) text.new-line "   "  t-name ")")
                                              (format "#" t-name " " (pprint-type-definition level type-func-info #.None module signature? recursive-type? type)))))
                                (text.join-with (format text.new-line " ")))]
            (if signature?
              member-docs
              (format "{" member-docs "}")))))

      [_ (#.Function input output)]
      (let [[ins out] (type.flatten-function type)]
        (format  "(-> " (|> ins (list;map (pprint-type-definition level type-func-info #.None module signature? recursive-type?)) (text.join-with " "))
                 " "
                 (pprint-type-definition level type-func-info #.None module signature? recursive-type? out)
                 ")"))

      [_ (#.Parameter idx)]
      (parameter->name type-func-info level idx)

      (^template [<tag> <pre> <post>]
        [_ (<tag> id)]
        (format <pre> (%.nat id) <post>))
      ([#.Var "⌈v:" "⌋"]
       [#.Ex  "⟨e:" "⟩"])

      (^template [<tag> <name> <flatten>]
        [_ (<tag> _)]
        (let [[level' body] (<flatten> type)
              args (level->args level level')
              body-doc (pprint-type-definition (n/+ level level') type-func-info tags module signature? recursive-type? body)]
          (format "(" <name> " " "[" (text.join-with " " args) "]"
                  (case tags
                    #.Nil
                    (format " " body-doc)

                    _
                    (format text.new-line (prefix-lines "  " body-doc)))
                  ")")))
      ([#.UnivQ "All" type.flatten-univ-q]
       [#.ExQ   "Ex"  type.flatten-ex-q])

      [true (#.Apply (#.Parameter 1) (#.Parameter 0))]
      (product.left type-func-info)

      [_ (#.Apply param fun)]
      (let [[type-func type-arguments] (type.flatten-application type)]
        (format  "(" (pprint-type-definition level type-func-info tags module signature? recursive-type? type-func) " " (|> type-arguments (list;map (pprint-type-definition level type-func-info #.None module signature? recursive-type?)) (text.join-with " ")) ")"))

      [_ (#.Named [_module _name] type)]
      (if (text;= module _module)
        _name
        (%.name [_module _name]))
      )))

(def: (pprint-type level type-func-name module type)
  (-> Nat Text Text Type Text)
  (case type
    (#.Primitive name params)
    (case params
      #.Nil
      (format "(primitive " (%.text name) ")")

      _
      (format "(primitive " (%.text name) " " (|> params (list;map (pprint-type level type-func-name module)) (list.interpose " ") (text.join-with "")) ")"))

    (#.Sum _)
    (let [members (type.flatten-variant type)]
      (format "(| " (|> members (list;map (pprint-type level type-func-name module)) (list.interpose " ") (text.join-with "")) ")"))

    (#.Product _)
    (let [members (type.flatten-tuple type)]
      (format "[" (|> members (list;map (pprint-type level type-func-name module)) (list.interpose " ") (text.join-with "")) "]"))

    (#.Function input output)
    (let [[ins out] (type.flatten-function type)]
      (format  "(-> "
               (|> ins (list;map (pprint-type level type-func-name module)) (list.interpose " ") (text.join-with ""))
               " "
               (pprint-type level type-func-name module out)
               ")"))

    (#.Parameter idx)
    (parameter->name [type-func-name (list)] level idx)

    (^template [<tag> <pre> <post>]
      (<tag> id)
      (format <pre> (%.nat id) <post>))
    ([#.Var "⌈" "⌋"]
     [#.Ex  "⟨" "⟩"])

    (^template [<tag> <name> <flatten>]
      (<tag> _)
      (let [[level' body] (<flatten> type)
            args (level->args level level')
            body-doc (pprint-type (n/+ level level') type-func-name module body)]
        (format "(" <name> " " "[" (|> args (list.interpose " ") (text.join-with "")) "]"
                (format " " body-doc)
                ")")))
    ([#.UnivQ "All" type.flatten-univ-q]
     [#.ExQ   "Ex"  type.flatten-ex-q])

    (#.Apply param fun)
    (let [[type-func type-arguments] (type.flatten-application type)]
      (format  "(" (pprint-type level type-func-name module type-func) " " (|> type-arguments (list;map (pprint-type level type-func-name module)) (list.interpose " ") (text.join-with "")) ")"))

    (#.Named [_module _name] type)
    (if (text;= module _module)
      _name
      (%.name [_module _name]))
    ))

(type: (Mutation a)
  (-> a a))

(type: Value [Text Code Type])

(type: Organization
  {#types (List Value)
   #macros (List [Text Code])
   #structures (List Value)
   #values (List Value)})

(def: (lux-module? module-name)
  (-> Text Bit)
  (or (text;= "lux" module-name)
      (text.starts-with? "lux/" module-name)))

(def: (add-definition [name [def-type def-annotations def-value]] organization)
  (-> [Text Definition] Organization Organization)
  (cond (type@= .Type def-type)
        (update@ #types
                 (: (Mutation (List Value))
                    (|>> (#.Cons [name def-annotations (:coerce Type def-value)])))
                 organization)

        (type@= .Macro def-type)
        (update@ #macros
                 (: (Mutation (List [Text Code]))
                    (|>> (#.Cons [name def-annotations])))
                 organization)

        (macro.structure? def-annotations)
        (update@ #structures
                 (: (Mutation (List Value))
                    (|>> (#.Cons [name def-annotations def-type])))
                 organization)

        ## else
        (update@ #values
                 (: (Mutation (List Value))
                    (|>> (#.Cons [name def-annotations def-type])))
                 organization)))

(def: name-sort
  (All [r] (-> [Text r] [Text r] Bit))
  (let [text;< (:: text.order <)]
    (function (_ [n1 _] [n2 _])
      (text;< n1 n2))))

(def: (organize-definitions defs)
  (-> (List [Text Definition]) Organization)
  (let [init {#types (list)
              #macros (list)
              #structures (list)
              #values (list)}]
    (|> (list;fold add-definition init defs)
        (update@ #types (list.sort name-sort))
        (update@ #macros (list.sort name-sort))
        (update@ #structures (list.sort name-sort))
        (update@ #values (list.sort name-sort)))))

(def: (unravel-type-func level type)
  (-> Nat Type Type)
  (if (n/> 0 level)
    (case type
      (#.UnivQ _env _type)
      (unravel-type-func (dec level) _type)

      _
      type)
    type))

(def: (unrecurse-type type)
  (-> Type Type)
  (case type
    (#.Apply _ (#.UnivQ _env _type))
    _type

    _
    type))

(exception: #export (anonymous-type-definition {type Type})
  (ex.report ["Type" (%.type type)]))

(def: (document-type module type def-annotations)
  (-> Text Type Code (Meta (Markdown Block)))
  (case type
    (#.Named type-name type)
    (do macro.monad
      [tags (macro.tags-of type-name)
       #let [[_ _name] type-name
             recursive-type? (macro.recursive-type? def-annotations)
             type-arguments (macro.type-arguments def-annotations)
             signature? (macro.signature? def-annotations)
             usage (case type-arguments
                     #.Nil
                     _name

                     _
                     (format "(" (text.join-with " " (list& _name type-arguments)) ")"))
             nesting (list.size type-arguments)]]
      (wrap (md.code (format (if signature? "(signature: " "(type: ")
                             (if recursive-type? "#rec " "")
                             usage text.new-line
                             (|> type
                                 (unravel-type-func nesting)
                                 (when> recursive-type? [unrecurse-type])
                                 (pprint-type-definition (dec nesting) [_name type-arguments] (maybe.default (list) tags) module signature? recursive-type?)
                                 (text.split-all-with text.new-line)
                                 (list;map (|>> (format "  ")))
                                 (text.join-with text.new-line))
                             ")"))))

    _
    (macro.fail (ex.construct anonymous-type-definition type))))

(def: (document-types module types)
  (-> Text (List Value) (Meta (Markdown Block)))
  (do macro.monad
    [type-docs (monad.map @
                          (: (-> Value (Meta (Markdown Block)))
                             (function (_ [name def-annotations type])
                               (do macro.monad
                                 [#let [?doc (macro.get-documentation def-annotations)]
                                  type-code (document-type module type def-annotations)]
                                 (wrap ($_ md.then
                                           (md.heading/3 name)
                                           (case ?doc
                                             (#.Some doc)
                                             (md.paragraph (md.text doc))

                                             _
                                             md.empty)
                                           type-code)))))
                          types)]
    (wrap (list;fold (function.flip md.then)
                     (md.heading/2 "Types")
                     type-docs))))

(def: (document-macros module-name names)
  (-> Text (List [Text Code]) (Markdown Block))
  (|> names
      (list;map (: (-> [Text Code] (Markdown Block))
                   (function (_ [name def-annotations])
                     ($_ md.then
                         (md.heading/3 name)
                         (<| (: (Markdown Block))
                             (maybe.default md.empty)
                             (do maybe.monad
                               [documentation (macro.get-documentation def-annotations)]
                               (wrap (md.code documentation))))))))
      (list;fold (function.flip md.then)
                 (md.heading/2 "Macros"))))

(template [<singular> <plural> <header>]
  [(def: (<singular> module type)
     (-> Text Type (Markdown Block))
     (md.code (pprint-type (dec 0) "?" module type)))

   (def: (<plural> module values)
     (-> Text (List Value) (Markdown Block))
     (|> values
         (list;map (function (_ [name def-annotations value-type])
                     (let [?doc (macro.get-documentation def-annotations)
                           usage (case (macro.function-arguments def-annotations)
                                   #.Nil
                                   name

                                   args
                                   (format "(" (text.join-with " " (list& name args)) ")"))]
                       ($_ md.then
                           (md.heading/3 usage)
                           (case ?doc
                             (#.Some doc)
                             (md.code doc)

                             _
                             md.empty)
                           (<singular> module value-type)))))
         (list;fold (function.flip md.then)
                    (md.heading/2 <header>))))]

  [document-structure document-structures "Structures"]
  [document-value     document-values     "Values"]
  )

(def: (enclose-lines pre+post block)
  (-> [Text Text] Text Text)
  (|> block
      (text.split-all-with text.new-line)
      (list;map (text.enclose pre+post))
      (text.join-with text.new-line)))

(def: (document-module [[module-name module] organization])
  (-> [[Text Module] Organization] (Meta [Text (Markdown Block)]))
  (do macro.monad
    [#let [(^slots [#types #macros #structures #values]) organization
           annotations (|> module
                           (get@ #.module-annotations)
                           (maybe.default (' {}))
                           macro.get-documentation)
           description (case annotations
                         (#.Some doc-text)
                         (md.quote (md.paragraph (md.text doc-text)))

                         #.None
                         md.empty)
           empty-block (: (Markdown Block) md.empty)]
     types-documentation (if (list.empty? types)
                           (wrap empty-block)
                           (document-types module-name types))
     #let [documentation ($_ md.then
                             types-documentation
                             (if (list.empty? macros) empty-block (document-macros module-name macros))
                             (if (list.empty? structures) empty-block (document-structures module-name structures))
                             (if (list.empty? values) empty-block (document-values module-name values)))]]
    (wrap [module-name
           ($_ md.then
               (md.heading/1 module-name)
               description
               documentation)])))

(exception: #export (io-error {error Text})
  error)

(def: (save-documentation! [module-name documentation])
  (-> [Text (Markdown Block)] (IO Any))
  (let [path (format (text.replace-all "/" "_" module-name) ".md")]
    (do io.monad
      [outcome (do (error.with io.monad)
                 [target (: (IO (Error (File IO)))
                            (file.get-file io.monad file.system path))]
                 (!.use (:: target over-write) (encoding.to-utf8 (md.markdown documentation))))]
      (case outcome
        (#error.Failure error)
        (wrap (log! (ex.construct io-error error)))

        (#error.Success _)
        (wrap [])))))

(macro: (gen-documentation! _)
  (do macro.monad
    [all-modules macro.modules
     #let [lux-modules (|> all-modules
                           (list.filter (function.compose lux-module? product.left))
                           (list.sort name-sort))]
     lux-exports (monad.map @ (function.compose macro.exports product.left)
                            lux-modules)
     module-documentation (|> (list;map organize-definitions lux-exports)
                              (list.zip2 lux-modules)
                              (monad.map @ document-module))
     #let [_ (io.run (monad.map io.monad save-documentation! module-documentation))]]
    (wrap (list))))

(gen-documentation!)

(program: args
  (io (log! "Done!")))