(.module:
  [library
   [lux (#- Name Type)
    [abstract
     [monad (#+ do)]
     [equivalence (#+ Equivalence)]]
    [control
     [pipe (#+ do> case>)]
     ["." try (#+ Try)]
     ["." exception (#+ exception:)]
     ["<>" parser
      ["<.>" xml (#+ Parser)]
      ["<.>" text]]
     [concurrency
      ["." async (#+ Async)]]]
    [data
     ["." product]
     ["." text
      ["%" format]
      [encoding
       ["." utf8]]]
     [format
      ["." xml (#+ XML)]]
     [collection
      ["." list ("#\." functor)]]]
    [math
     [number
      ["n" nat]]]
    ["." time (#+ Time)
     ["." instant (#+ Instant)]
     ["." date (#+ Date)]
     ["." year]
     ["." month]]
    [world
     [net
      ["." uri (#+ URI)]]]]]
  ["." //
   ["/#" // #_
    [repository (#+ Repository)]
    ["#." artifact (#+ Group Name Version Artifact)
     ["#/." time]
     ["#/." type (#+ Type)]
     ["#/." versioning (#+ Versioning)]
     ["#/." snapshot
      ["#/." version]
      ["#/." stamp]]]]])

(type: .public Metadata
  (Record
   {#artifact Artifact
    #versioning Versioning}))

(template [<definition> <tag>]
  [(def: <definition> xml.Tag ["" <tag>])]

  [<group> "groupId"]
  [<name> "artifactId"]
  [<version> "version"]
  [<metadata> "metadata"]
  )

(template [<name> <type> <tag> <pre>]
  [(def: <name>
     (-> <type> XML)
     (|>> <pre> #xml.Text list (#xml.Node <tag> xml.attributes)))]

  [group_format Group ..<group> (|>)]
  [name_format Name ..<name> (|>)]
  [version_format Version ..<version> (|>)]
  )

(def: .public (format (^slots [#artifact #versioning]))
  (-> Metadata XML)
  (let [(^slots [#///artifact.group #///artifact.name #///artifact.version]) artifact]
    (#xml.Node ..<metadata>
               xml.attributes
               (list (..group_format group)
                     (..name_format name)
                     (..version_format version)
                     (///artifact/versioning.format versioning)))))

(def: (text tag)
  (-> xml.Tag (Parser Text))
  (<| (<xml>.node tag)
      <xml>.text))

(def: .public parser
  (Parser Metadata)
  (<| (<xml>.node ..<metadata>)
      (do {! <>.monad}
        [group (<xml>.somewhere (..text ..<group>))
         name (<xml>.somewhere (..text ..<name>))
         version (<xml>.somewhere (..text ..<version>))
         versioning (with_expansions [<default_version> {#///artifact/snapshot/version.extension ///artifact/type.jvm_library
                                                         #///artifact/snapshot/version.value version
                                                         #///artifact/snapshot/version.updated ///artifact/time.epoch}]
                      (|> (<xml>.somewhere ///artifact/versioning.parser)
                          (\ ! each
                             (revised@ #///artifact/versioning.versions
                                       (: (-> (List ///artifact/snapshot/version.Version)
                                              (List ///artifact/snapshot/version.Version))
                                          (|>> (case> (^ (list))
                                                      (list <default_version>)

                                                      versions
                                                      versions)))))
                          (<>.else {#///artifact/versioning.snapshot #///artifact/snapshot.Local
                                    #///artifact/versioning.last_updated ///artifact/time.epoch
                                    #///artifact/versioning.versions (list <default_version>)})))]
        (in {#artifact {#///artifact.group group
                        #///artifact.name name
                        #///artifact.version version}
             #versioning versioning}))))

(def: .public equivalence
  (Equivalence Metadata)
  ($_ product.equivalence
      ///artifact.equivalence
      ///artifact/versioning.equivalence
      ))

(def: .public uri
  (-> Artifact URI)
  //.remote_artifact_uri)

(def: .public (read repository artifact)
  (-> (Repository Async) Artifact (Async (Try Metadata)))
  (do async.monad
    [project (\ repository download (..uri artifact))]
    (case project
      (#try.Success project)
      (in (|> project
              (do> try.monad
                   [(\ utf8.codec decoded)]
                   [(\ xml.codec decoded)]
                   [list (<xml>.result ..parser)])))
      
      (#try.Failure error)
      (in (#try.Success
           {#artifact artifact
            #versioning ///artifact/versioning.init})))))

(def: .public (write repository artifact metadata)
  (-> (Repository Async) Artifact Metadata (Async (Try Any)))
  (|> metadata
      ..format
      (\ xml.codec encoded)
      (\ utf8.codec encoded)
      (\ repository upload (..uri artifact))))