Object subclass: GSM0808IE [
    <category: 'osmo-message'>
    <comment: 'Base class of IEs for GSM0808'>

    type [
        "Go through the elementId of the class"
        ^ self class elementId
    ]
]

Object subclass: GSM0808Helper [
    GSM0808Helper class >> msgComplL3   [ <category: 'spec'> ^ 16r57 ]
    GSM0808Helper class >> msgReset     [ <category: 'spec'> ^ 16r30 ]
    GSM0808Helper class >> msgResetAck  [ <category: 'spec'> ^ 16r31 ]
    GSM0808Helper class >> msgClear     [ <category: 'spec'> ^ 16r20 ]
    GSM0808Helper class >> msgClearComp [ <category: 'spec'> ^ 16r21 ]
]

Object subclass: LAI [
    | mcc mnc |
    <category: 'osmo-message'>
    <comment: 'Generate a Location Area Identifier'>

    LAI class >> initWith: mcc mnc: mnc [
        ^ self new
            mcc: mcc;
            mnc: mnc;
            yourself
    ]

    LAI class >> parseFrom: aByteArray [
        | mcc mnc |

        mcc := ByteArray new: 3.
        mcc at: 1 put: ((aByteArray at: 1) bitAnd: 16rF).
        mcc at: 2 put: (((aByteArray at: 1) bitAnd: 16rF0) bitShift: -4).
        mcc at: 3 put: ((aByteArray at: 2) bitAnd: 16rF).
        mcc := BCD decode: mcc.

        mnc := ByteArray new: 3.
        mnc at: 1 put: ((aByteArray at: 3) bitAnd: 16rF).
        mnc at: 2 put: (((aByteArray at: 3) bitAnd: 16rF0) bitShift: -4).
        mnc at: 3 put: (((aByteArray at: 2) bitAnd: 16rF0) bitShift: -4).

        "Need to check if we have two or three bytes here."
        (mnc at: 3) = 16rF
            ifTrue: [
                mnc := BCD decode: (mnc copyFrom: 1 to: 2).
            ]
            ifFalse: [
                mnc := BCD decode: mnc.
            ].

        ^ LAI initWith: mcc mnc: mnc.
    ]

    LAI class >> generateLAI: mcc mnc: mnc [
        <category: 'creation'>
        | lai |

        lai := LAI initWith: mcc mnc: mnc.
        ^ lai toMessage asByteArray.
    ]

    writeOn: aMsg [
        | mcc_bcd mnc_bcd lai_0 lai_1 lai_2 |
        mcc_bcd := BCD encode: mcc.
        mnc_bcd := BCD encode: mnc.

        lai_0 := (mcc_bcd at: 1) bitOr: ((mcc_bcd at: 2) bitShift: 4).
        lai_1 := mcc_bcd at: 3.

        mnc > 99
            ifTrue: [
                lai_1 := lai_1 bitOr: ((mnc_bcd at: 3) bitShift: 4).
                lai_2 := (mnc_bcd at: 1) bitOr: ((mnc_bcd at: 2) bitShift: 4)
            ]
            ifFalse: [
                lai_1 := lai_1 bitOr: (16rF bitShift: 4).
                lai_2 := (mnc_bcd at: 2) bitOr: ((mnc_bcd at: 3) bitShift: 4)
            ].

        aMsg putByte: lai_0.
        aMsg putByte: lai_1.
        aMsg putByte: lai_2.
    ]

    mcc [
        ^ mcc
    ]

    mcc: aMcc [
        mcc := aMcc.
    ]

    mnc [
        ^ mnc
    ]

    mnc: aMnc [
        mnc := aMnc.
    ]

]

GSM0808IE subclass: GSMCellIdentifier [
    <category: 'osmo-message'>
    <comment: 'Generate a GSM0808 Cell Identifier'>

    | lai lac ci |
    GSMCellIdentifier class >> elementId [ <category: 'spec'> ^ 5 ]
    GSMCellIdentifier class >> initWith: mcc mnc: mnc lac: lac ci: ci [
        <category: 'creation'>
        ^ (self new)
            mcc: mcc mnc: mnc lac: lac ci: ci;
            yourself
    ]

    GSMCellIdentifier class >> parseFrom: aByteArray [
        | lai lac ci |
        (aByteArray at: 3) = 0
            ifFalse: [
            Error signal: 'Can not handle Cell Identifier of type != 0'.
        ].

        lai := LAI parseFrom: (aByteArray copyFrom: 4).
        lac := (aByteArray ushortAt: 7) swap16.
        ci  := (aByteArray ushortAt: 9) swap16.

        ^ self new
            mcc: lai mcc mnc: lai mnc lac: lac ci: ci;
            yourself
    ]

    mcc: aMcc mnc: aMnc lac: aLac ci: aCi [
        <category: 'creation'>
        lai := LAI initWith: aMcc mnc: aMnc.
        lac := aLac.
        ci := aCi.
    ]

    mcc [
        <category: 'access'>
        ^ lai mcc
    ]

    mnc [
        <category: 'access'>
        ^ lai mnc
    ]

    lac [
        <category: 'access'>
        ^ lac
    ]

    ci [
        <category: 'access'>
        ^ ci
    ]

    writeOn: aMsg [
        <category: 'creation'>
        | lai_data |
        lai_data := lai toMessageOrByteArray.

        aMsg putByte: self class elementId.
        aMsg putByte: 1 + lai_data size + 2 + 2.
        aMsg putByte: 0.
        aMsg putByteArray: lai_data.
        aMsg putLen16: lac.
        aMsg putLen16: ci.
    ]
]

GSM0808IE subclass: GSMLayer3Info [
    <category: 'osmo-message'>
    <comment: 'Generate a Layer3 IE'>
    | data |
    GSMLayer3Info class >> elementId [ <category: 'spec'> ^ 23 ]
    GSMLayer3Info class >> initWith: data [
        <category: 'creation'>
        ^ (self new)
            data: data;
            yourself
    ]

    GSMLayer3Info class >> parseFrom: aByteArray [
        | size |
        size := aByteArray at: 2.
        ^ GSMLayer3Info initWith: (aByteArray copyFrom: 3 to: 2 + size)
    ]

    data: aData [
        <category: 'creation'>
        data := aData
    ]

    data [
        ^ data
    ]

    writeOn: aMsg [
        | dat |
        <category: 'creation'>
        aMsg putByte: self class elementId.

        dat := data toMessageOrByteArray.
        aMsg putByte: dat size.
        aMsg putByteArray: dat.
    ]
]

GSM0808IE subclass: GSMCauseIE [
    | cause |

    <category: 'osmo-message'>
    <comment: 'Generate a CauseIE'>
    "TODO: Only simple ones are supported right now"

    GSMCauseIE class >> elementId [ <category: 'spec'> ^ 4 ]

    GSMCauseIE class >> initWith: aCause [
        ^ self new
            cause: aCause;
            yourself
    ]
    GSMCauseIE class >> parseFrom: aByteArray [
        | size |
        size := aByteArray at: 2.
        size = 1
            ifFalse: [
            ^ Error signal: 'Extended error codes are not supported.'.
        ].

        ^ GSMCauseIE initWith: (aByteArray at: 3)
    ]

    cause [ ^ cause ]
    cause: aCause [ cause := aCause ]

    writeOn: aMsg [
        aMsg putByte: self class elementId.
        aMsg putByte: 1.
        aMsg putByte: cause.
    ]
]