(;module:
  lux
  (lux (control [monad #+ do]
                ["ex" exception #+ exception:])
       (data [maybe]
             [product]
             ["e" error]
             [text "text/" Eq<Text>]
             text/format
             (coll [list]))
       [meta]
       (meta (type ["tc" check])))
  (luxc (lang ["la" analysis])))

(type: #export Eval
  (-> Type Code (Meta Top)))

(type: #export Analyser
  (-> Code (Meta la;Analysis)))

(def: #export version Text "0.6.0")

(def: #export (fail message)
  (All [a] (-> Text (Meta a)))
  (do meta;Monad<Meta>
    [[file line col] meta;cursor
     #let [location (format file
                            "," (|> line nat-to-int %i)
                            "," (|> col nat-to-int %i))]]
    (meta;fail (format message "\n\n"
                       "@ " location))))

(def: #export (assert message test)
  (-> Text Bool (Meta Unit))
  (if test
    (:: meta;Monad<Meta> wrap [])
    (fail message)))

(def: #export (throw exception message)
  (All [a] (-> ex;Exception Text (Meta a)))
  (fail (exception message)))

(def: #export (with-expected-type expected action)
  (All [a] (-> Type (Meta a) (Meta a)))
  (function [compiler]
    (case (action (set@ #;expected (#;Some expected) compiler))
      (#e;Success [compiler' output])
      (let [old-expected (get@ #;expected compiler)]
        (#e;Success [(set@ #;expected old-expected compiler')
                     output]))

      (#e;Error error)
      (#e;Error error))))

(def: #export (with-type-env action)
  (All [a] (-> (tc;Check a) (Meta a)))
  (function [compiler]
    (case (action (get@ #;type-context compiler))
      (#e;Error error)
      ((fail error) compiler)

      (#e;Success [context' output])
      (#e;Success [(set@ #;type-context context' compiler)
                   output]))))

(def: #export (infer actualT)
  (-> Type (Meta Unit))
  (do meta;Monad<Meta>
    [expectedT meta;expected-type]
    (with-type-env
      (tc;check expectedT actualT))))

(def: #export (pl-get key table)
  (All [a] (-> Text (List [Text a]) (Maybe a)))
  (case table
    #;Nil
    #;None

    (#;Cons [k' v'] table')
    (if (text/= key k')
      (#;Some v')
      (pl-get key table'))))

(def: #export (pl-contains? key table)
  (All [a] (-> Text (List [Text a]) Bool))
  (case (pl-get key table)
    (#;Some _)
    true

    #;None
    false))

(def: #export (pl-put key val table)
  (All [a] (-> Text a (List [Text a]) (List [Text a])))
  (case table
    #;Nil
    (list [key val])

    (#;Cons [k' v'] table')
    (if (text/= key k')
      (#;Cons [key val]
              table')
      (#;Cons [k' v']
              (pl-put key val table')))))

(def: #export (pl-update key f table)
  (All [a] (-> Text (-> a a) (List [Text a]) (List [Text a])))
  (case table
    #;Nil
    #;Nil

    (#;Cons [k' v'] table')
    (if (text/= key k')
      (#;Cons [k' (f v')] table')
      (#;Cons [k' v'] (pl-update key f table')))))

(def: #export (with-source-code source action)
  (All [a] (-> Source (Meta a) (Meta a)))
  (function [compiler]
    (let [old-source (get@ #;source compiler)]
      (case (action (set@ #;source source compiler))
        (#e;Error error)
        (#e;Error error)

        (#e;Success [compiler' output])
        (#e;Success [(set@ #;source old-source compiler')
                     output])))))

(def: #export (with-stacked-errors handler action)
  (All [a] (-> (-> [] Text) (Meta a) (Meta a)))
  (function [compiler]
    (case (action compiler)
      (#e;Success [compiler' output])
      (#e;Success [compiler' output])

      (#e;Error error)
      (#e;Error (if (text/= "" error)
                  (handler [])
                  (format (handler []) "\n\n-----------------------------------------\n\n" error))))))

(def: fresh-bindings
  (All [k v] (Bindings k v))
  {#;counter +0
   #;mappings (list)})

(def: fresh-scope
  Scope
  {#;name     (list)
   #;inner    +0
   #;locals   fresh-bindings
   #;captured fresh-bindings})

(def: #export (with-scope action)
  (All [a] (-> (Meta a) (Meta [Scope a])))
  (function [compiler]
    (case (action (update@ #;scopes (|>. (#;Cons fresh-scope)) compiler))
      (#e;Success [compiler' output])
      (case (get@ #;scopes compiler')
        #;Nil
        (#e;Error "Impossible error: Drained scopes!")

        (#;Cons head tail)
        (#e;Success [(set@ #;scopes tail compiler')
                     [head output]]))

      (#e;Error error)
      (#e;Error error))))

(def: #export (with-current-module name action)
  (All [a] (-> Text (Meta a) (Meta a)))
  (function [compiler]
    (case (action (set@ #;current-module (#;Some name) compiler))
      (#e;Success [compiler' output])
      (#e;Success [(set@ #;current-module
                         (get@ #;current-module compiler)
                         compiler')
                   output])

      (#e;Error error)
      (#e;Error error))))

(def: #export (with-cursor cursor action)
  (All [a] (-> Cursor (Meta a) (Meta a)))
  (if (text/= "" (product;left cursor))
    action
    (function [compiler]
      (let [old-cursor (get@ #;cursor compiler)]
        (case (action (set@ #;cursor cursor compiler))
          (#e;Success [compiler' output])
          (#e;Success [(set@ #;cursor old-cursor compiler')
                       output])

          (#e;Error error)
          (#e;Error error))))))

(def: (normalize-char char)
  (-> Nat Text)
  (case char
    (^ (char "*")) "_ASTER_"
    (^ (char "+")) "_PLUS_"
    (^ (char "-")) "_DASH_"
    (^ (char "/")) "_SLASH_"
    (^ (char "\\")) "_BSLASH_"
    (^ (char "_")) "_UNDERS_"
    (^ (char "%")) "_PERCENT_"
    (^ (char "$")) "_DOLLAR_"
    (^ (char "'")) "_QUOTE_"
    (^ (char "`")) "_BQUOTE_"
    (^ (char "@")) "_AT_"
    (^ (char "^")) "_CARET_"
    (^ (char "&")) "_AMPERS_"
    (^ (char "=")) "_EQ_"
    (^ (char "!")) "_BANG_"
    (^ (char "?")) "_QM_"
    (^ (char ":")) "_COLON_"
    (^ (char ".")) "_PERIOD_"
    (^ (char ",")) "_COMMA_"
    (^ (char "<")) "_LT_"
    (^ (char ">")) "_GT_"
    (^ (char "~")) "_TILDE_"
    (^ (char "|")) "_PIPE_"
    _
    (text;from-code char)))

(def: underflow Nat (n.dec +0))

(def: #export (normalize-name name)
  (-> Text Text)
  (loop [idx (n.dec (text;size name))
         output ""]
    (if (n.= underflow idx)
      output
      (recur (n.dec idx) (format (|> (text;nth idx name) maybe;assume normalize-char) output)))))