! Copyright (C) 2008, 2010 Daniel Ehrenberg, Slava Pestov.
! See http://factorcode.org/license.txt for BSD license.
USING: accessors combinators destructors io io.streams.plain
kernel math namespaces sbufs sequences sequences.private
splitting strings ;
IN: io.encodings

! The encoding descriptor protocol

GENERIC: guess-encoded-length ( string-length encoding -- byte-length )
GENERIC: guess-decoded-length ( byte-length encoding -- string-length )

M: object guess-decoded-length drop ; inline
M: object guess-encoded-length drop ; inline

GENERIC: decode-char ( stream encoding -- char/f )

GENERIC: encode-char ( char stream encoding -- )

GENERIC: encode-string ( string stream encoding -- )

M: object encode-string [ encode-char ] 2curry each ; inline

GENERIC: <decoder> ( stream encoding -- newstream )

CONSTANT: replacement-char 0xfffd

TUPLE: decoder { stream read-only } { code read-only } { cr boolean } ;
INSTANCE: decoder input-stream

ERROR: decode-error ;

GENERIC: <encoder> ( stream encoding -- newstream )

TUPLE: encoder { stream read-only } { code read-only } ;
INSTANCE: encoder output-stream

ERROR: encode-error ;

! Decoding

M: object <decoder> f decoder boa ; inline

<PRIVATE

: cr+ ( stream -- ) t >>cr drop ; inline

: cr- ( stream -- ) f >>cr drop ; inline

: >decoder< ( decoder -- stream encoding )
    [ stream>> ] [ code>> ] bi ; inline

M: decoder stream-element-type
    drop +character+ ; inline

: (read1) ( decoder -- ch )
    >decoder< decode-char ; inline

: fix-cr ( decoder c -- c' )
    over cr>> [
        over cr-
        dup CHAR: \n eq? [ drop (read1) ] [ nip ] if
    ] [ nip ] if ; inline

M: decoder stream-read1 ( decoder -- ch )
    dup (read1) fix-cr ; inline

: (read-first) ( n buf decoder -- buf stream encoding n c )
    [ rot [ >decoder< ] dip 2over decode-char ]
    [ swap fix-cr ] bi ; inline

: (store-read) ( buf stream encoding n c i -- buf stream encoding n )
    [ rot [ set-nth-unsafe ] keep ] 2curry 3dip ; inline

: (finish-read) ( buf stream encoding n i -- i )
    2nip 2nip ; inline

: (read-next) ( stream encoding n i -- stream encoding n i c )
    [ 2dup decode-char ] 2dip rot ; inline

: (read-rest) ( buf stream encoding n i -- count )
    2dup = [ (finish-read) ] [
        (read-next) [
            swap [ (store-read) ] [ 1 + ] bi (read-rest)
        ] [ (finish-read) ] if*
    ] if ; inline recursive

M: decoder stream-read-unsafe
    pick 0 = [ 3drop 0 ] [
        (read-first) [
            0 (store-read)
            1 (read-rest)
        ] [ 2drop 2drop 0 ] if*
    ] if ; inline

M: decoder stream-contents
    (stream-contents-by-element) ;

: line-ends/eof ( stream str -- str ) f like swap cr- ; inline

: line-ends\r ( stream str -- str ) swap cr+ ; inline

: line-ends\n ( stream str -- str )
    over cr>> over empty? and
    [ drop dup cr- stream-readln ] [ swap cr- ] if ; inline

: handle-readln ( stream str ch -- str )
    {
        { f [ line-ends/eof ] }
        { CHAR: \r [ line-ends\r ] }
        { CHAR: \n [ line-ends\n ] }
    } case ; inline

! If the stop? branch is taken convert the sbuf to a string
! If sep is present, returns ``string sep'' (string can be "")
! If sep is f, returns ``string f'' or ``f f''
: read-until-loop ( buf quot: ( -- char stop? ) -- string/f sep/f )
    dup call
    [ nip [ "" like ] dip [ f like f ] unless* ]
    [ pick push read-until-loop ] if ; inline recursive

: (read-until) ( quot -- string/f sep/f )
    [ 100 <sbuf> ] dip read-until-loop ; inline

: decoder-read-until ( seps stream encoding -- string/f sep/f )
    [ decode-char dup [ dup rot member? ] [ 2drop f t ] if ] 3curry
    (read-until) ;

M: decoder stream-read-until >decoder< decoder-read-until ;

: decoder-readln ( stream encoding -- string/f sep/f )
    [ decode-char dup [ dup "\r\n" member? ] [ drop f t ] if ] 2curry
    (read-until) ;

M: decoder stream-readln dup >decoder< decoder-readln handle-readln ;

M: decoder dispose stream>> dispose ;

! Encoding
M: object <encoder> encoder boa ; inline

: >encoder< ( encoder -- stream encoding )
    [ stream>> ] [ code>> ] bi ; inline

M: encoder stream-element-type
    drop +character+ ; inline

M: encoder stream-write1
    >encoder< encode-char ; inline

M: encoder stream-write
    >encoder< encode-string ; inline

M: encoder dispose stream>> dispose ; inline

M: encoder stream-flush stream>> stream-flush ; inline

INSTANCE: encoder plain-writer
PRIVATE>

GENERIC# re-encode 1 ( stream encoding -- newstream )

M: object re-encode <encoder> ;

M: encoder re-encode [ stream>> ] dip re-encode ;

: encode-output ( encoding -- )
    output-stream [ swap re-encode ] change ;

: with-encoded-output ( encoding quot -- )
    [ [ output-stream get ] dip re-encode ] dip
    with-output-stream* ; inline

GENERIC# re-decode 1 ( stream encoding -- newstream )

M: object re-decode <decoder> ;

M: decoder re-decode [ stream>> ] dip re-decode ;

: decode-input ( encoding -- )
    input-stream [ swap re-decode ] change ;

: with-decoded-input ( encoding quot -- )
    [ [ input-stream get ] dip re-decode ] dip
    with-input-stream* ; inline