"{ Package: 'stx:libbasic2' }"

"{ NameSpace: Smalltalk }"

Base64Coder subclass:#Base64UrlCoder
	instanceVariableNames:''
	classVariableNames:'Base64UrlMapping Base64UrlReverseMapping'
	poolDictionaries:''
	category:'System-Storage'
!

!Base64UrlCoder class methodsFor:'documentation'!

documentation
"
    A variant of base64 encoding which generates url- and filename save encodings.
    Same as Base64 except that instead of plus and slash, minus and underline are generated.

    The main entry point API is
        Base64UrlCoder encode:aStringOrBytes
    and
        Base64UrlCoder decode:aString

    If the decoder should return a string, use
        Base64UrlCoder decodeAsString:aString.

    [author:]
        Claus Gittinger

    [see also:]
        RFC https://tools.ietf.org/html/rfc4648

    [instance variables:]

    [class variables:]
        Base64UrlMapping         String   Mapping from bytes (with 6 valid bits)
                                          to Base64Url characters
        Base64UrlReverseMapping  Array    Mapping from Base64Url characters to 6-bit-Bytes
"
!

examples
"
                                                                [exBegin]
   (Base64Coder encode:#[0 0 16r3F]) = 'AAA/'
                                                                [exEnd]
                                                                [exBegin]
   (Base64Coder decode:'AAA/') = #[0 0 63]
                                                                [exEnd]

                                                                [exBegin]
   (Base64UrlCoder encode:#[0 0 16r3F]) = 'AAA_'
                                                                [exEnd]
                                                                [exBegin]
   (Base64UrlCoder decode:'AAA_') = #[0 0 63]
                                                                [exEnd]
"
! !

!Base64UrlCoder class methodsFor:'initialization'!

initializeMappings
    "initialize class variables"

    Base64UrlMapping isNil ifTrue:[
        "65 characters representing the 6-bit values from 0-63 and one pad character"
        "/ notice: minus and underline instead of plus and slash
        Base64UrlMapping := 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_='.
        Base64UrlReverseMapping := self reverseMappingFor:Base64UrlMapping.
    ].

    "
     Base64UrlMapping := nil.
     self initializeMappings
    "

    "Created: / 30-09-2018 / 15:20:47 / Claus Gittinger"
!

mapping
    ^ Base64UrlMapping

    "Created: / 30-09-2018 / 15:31:14 / Claus Gittinger"
!

reverseMapping
    ^ Base64UrlReverseMapping

    "Created: / 30-09-2018 / 15:31:21 / Claus Gittinger"
! !

!Base64UrlCoder class methodsFor:'documentation'!

version_CVS
    ^ '$Header$'
! !