compile discounts on master data based on matrix

Hi, 

here is my next approach. As discussed I constructed all relevant IDs. Logic as follows:
- if an attribute has no specific value "XXXX" is set in order to avoid the empty/blank problem 
- then we have IDs of the form SET-CAT-FAM-GRU with A-XXXX-ABC-DE and the like.
- then an id 1111 means all attributes have a value and there are no blanks, e.g. 1000 means only the SET is non-blank and so on. 
- in this terminology there are GRU discounts that have 1xx1 signature
- FAM discounts have a  1x1x signature and so forth
TBL2 gets the calculated columns as follows:

GRUDiscount =
VAR thisSET = TBL2[SET]
VAR thisFAM = TBL2[FAM]
VAR thisCAT = TBL2[CAT]
VAR thisGRU = TBL2[GRU]
VAR hasGRU =
    IF ( ISBLANK ( thisGRU ) = FALSE () && thisGRU <> "", TRUE (), FALSE () )
VAR hasSET =
    IF ( ISBLANK ( thisSET ) = FALSE () && thisSET <> "", TRUE (), FALSE () )
VAR hasCAT =
    IF ( ISBLANK ( thisCAT ) = FALSE () && thisCAT <> "", TRUE (), FALSE () )
VAR hasFAM =
    IF ( ISBLANK ( thisFAM ) = FALSE () && thisFAM <> "", TRUE (), FALSE () ) //GRU IDs 
/// 1111
VAR ID_1111 =
    IF (
        hasCAT && hasGRU
            && hasFAM,
        COMBINEVALUES ( "-", thisSET, thisCAT, thisFAM, thisGRU ),
        "None"
    ) //  1001
VAR ID_1001 =
    IF ( hasGRU, COMBINEVALUES ( "-", thisSET, "XXXX", "XXXX", thisGRU ), "None" ) // 1101 
VAR ID_1101 =
    IF (
        hasCAT && hasGRU,
        COMBINEVALUES ( "-", thisSET, thisCAT, "XXXX", thisGRU ),
        "None"
    ) // 1011
VAR ID_1011 =
    IF (
        hasGRU && hasFAM,
        COMBINEVALUES ( "-", thisSET, "XXXX", thisFAM, thisGRU ),
        "None"
    )
RETURN
    CALCULATE (
        FIRSTNONBLANK ( TBL1[VAL], 0 ),
        FILTER (
            TBL1,
            TBL1[ID] == ID_1111
                || TBL1[ID] == ID_1001
                || TBL1[ID] == ID_1101
                || TBL1[ID] == ID_1011
                && TBL1[VAL] <> 0
        )
    )

FAMDiscount =
VAR thisSET = TBL2[SET]
VAR thisFAM = TBL2[FAM]
VAR thisCAT = TBL2[CAT]
VAR thisGRU = TBL2[GRU]
VAR hasGRU =
    IF ( ISBLANK ( thisGRU ) = FALSE () && thisGRU <> "", TRUE (), FALSE () )
VAR hasSET =
    IF ( ISBLANK ( thisSET ) = FALSE () && thisSET <> "", TRUE (), FALSE () )
VAR hasCAT =
    IF ( ISBLANK ( thisCAT ) = FALSE () && thisCAT <> "", TRUE (), FALSE () )
VAR hasFAM =
    IF ( ISBLANK ( thisFAM ) = FALSE () && thisFAM <> "", TRUE (), FALSE () ) //FAM IDs 
/// 1110
VAR ID_1110 =
    IF (
        hasCAT && hasFAM,
        COMBINEVALUES ( "-", thisSET, thisCAT, thisFAM, "XXXX" ),
        "None"
    ) //  1010
VAR ID_1010 =
    IF ( hasFAM, COMBINEVALUES ( "-", thisSET, "XXXX", thisFAM, "XXXX" ), "None" )
RETURN
    CALCULATE (
        FIRSTNONBLANK ( TBL1[VAL], 0 ),
        FILTER ( TBL1, TBL1[ID] == ID_1110 || TBL1[ID] == ID_1010 && TBL1[VAL] <> 0 )
    )
CATDiscount = 
VAR thisSET = TBL2[SET]
VAR thisFAM = TBL2[FAM]
VAR thisCAT = TBL2[CAT]
VAR thisGRU = TBL2[GRU] 
VAR hasGRU = if(ISBLANK(thisGRU) = FALSE() && thisGRU <> "", TRUE(), FALSE())
VAR hasSET = if(ISBLANK(thisSET) = FALSE() && thisSET <> "", TRUE(), FALSE())
VAR hasCAT = if(ISBLANK(thisCAT) = FALSE() && thisCAT <> "", TRUE(), FALSE())
VAR hasFAM = if(ISBLANK(thisFAM) = FALSE() && thisFAM <> "", TRUE(), FALSE())

//CAT IDs 
/// 1100
VAR ID_1100 = if(hasCAT , COMBINEVALUES("-", thisSET, thisCAT, "XXXX", "XXXX"), "None")

return 
CALCULATE(FIRSTNONBLANK(TBL1[VAL],0), FILTER(TBL1, TBL1[ID] == ID_1100 && TBL1[VAL] <> 0))

SETDiscount =
VAR thisSET = TBL2[SET]
VAR thisFAM = TBL2[FAM]
VAR thisCAT = TBL2[CAT]
VAR thisGRU = TBL2[GRU]
VAR hasGRU =
    IF ( ISBLANK ( thisGRU ) = FALSE () && thisGRU <> "", TRUE (), FALSE () )
VAR hasSET =
    IF ( ISBLANK ( thisSET ) = FALSE () && thisSET <> "", TRUE (), FALSE () )
VAR hasCAT =
    IF ( ISBLANK ( thisCAT ) = FALSE () && thisCAT <> "", TRUE (), FALSE () )
VAR hasFAM =
    IF ( ISBLANK ( thisFAM ) = FALSE () && thisFAM <> "", TRUE (), FALSE () ) //SET IDs 
/// 1000
VAR ID_1000 =
    COMBINEVALUES ( "-", thisSET, "XXXX", "XXXX", "XXXX" )
RETURN
    CALCULATE (
        FIRSTNONBLANK ( TBL1[VAL], 0 ),
        FILTER ( TBL1, TBL1[ID] == ID_1000 && TBL1[VAL] <> 0 )
    )
Discount =
IF (
    TBL2[GRUDiscount] <> 0,
    TBL2[GRUDiscount],
    IF (
        TBL2[FAMDiscount] <> 0,
        TBL2[FAMDiscount],
        IF ( TBL2[CATDiscount] <> 0, TBL2[CATDiscount], TBL2[SETDiscount] )
    )
)

Basically, all cases are intended to be covered. In case there are multiple discounts, the most specific is applied. 
Assumption is there is only one discount? If not firstnonblank can be replaced by sum and all discounts could be summed up (SET, CAT, ...)

The discount for SKU10 is now assigned. Here the updated file:
Discount.2.0.pbix
This is only tested in the sense that it reproduces the discounts for the 10 SKUs. You might test it further to find bugs. More importantly, it would be good to have a common understanding that this is one way to approach the problem. We can touch base on Monday, if necessary. 
Best regards 
Christian