 USING: alien.c-types alien.syntax audio combinators
 combinators.short-circuit io io.binary io.encodings.binary
 io.files io.streams.byte-array kernel locals math
-sequences alien.data ;
+sequences alien alien.data classes.struct accessors ;
 IN: audio.wav
 
 CONSTANT: RIFF-MAGIC "RIFF"

CONSTANT: FMT-MAGIC  "fmt "
CONSTANT: DATA-MAGIC "data"

C-STRUCT: riff-chunk-header
    { "char[4]" "id" }
    { "uchar[4]" "size" }
    ;

C-STRUCT: riff-chunk
    { "riff-chunk-header" "header" }
    { "char[4]" "format" }
    ;

C-STRUCT: wav-fmt-chunk
    { "riff-chunk-header" "header" }
    { "uchar[2]" "audio-format" }
    { "uchar[2]" "num-channels" }
    { "uchar[4]" "sample-rate" }
    { "uchar[4]" "byte-rate" }
    { "uchar[2]" "block-align" }
    { "uchar[2]" "bits-per-sample" }
    ;

C-STRUCT: wav-data-chunk
    { "riff-chunk-header" "header" }
    { "uchar[0]" "body" }
    ;

ERROR: invalid-wav-file ;


: read-chunk ( -- byte-array/f )
    4 ensured-read [ 4 ensured-read* dup le> ensured-read* 3append ] [ f ] if* ;
: read-riff-chunk ( -- byte-array/f )
    riff-chunk heap-size ensured-read* ;

: id= ( chunk id -- ? )
    [ 4 head ] dip sequence= ; inline

: check-chunk ( chunk id class -- ? )
    heap-size [ id= ] [ [ length ] dip >= ] bi-curry* bi and ;

:: read-wav-chunks ( -- fmt data )
    f :> fmt! f :> data!
    [ { [ fmt data and not ] [ read-chunk ] } 0&& dup ]
    [ {
        { [ dup FMT-MAGIC  wav-fmt-chunk  check-chunk ] [ wav-fmt-chunk  memory>struct fmt!  ] }
        { [ dup DATA-MAGIC wav-data-chunk check-chunk ] [ wav-data-chunk memory>struct data! ] }
    } cond ] while drop
    fmt data 2dup and [ invalid-wav-file ] unless ;

: verify-wav ( chunk -- )
    {
        [ RIFF-MAGIC id= ]
        [ riff-chunk memory>struct format>> 4 memory>byte-array WAVE-MAGIC id= ]
    } 1&&
    [ invalid-wav-file ] unless ;

: (read-wav) ( -- audio )
    read-wav-chunks
    [
        [ num-channels>>    2 memory>byte-array le> ]
        [ bits-per-sample>> 2 memory>byte-array le> ]
        [ sample-rate>>     4 memory>byte-array le> ] tri
    ] [
        [ header>> size>> 4 memory>byte-array le> dup ]
        [ body>> >c-ptr ] bi swap memory>byte-array
    ] bi* <audio> ;

: read-wav ( filename -- audio )
