How to extract rows with specific columns and values between two data tables?

I have two sorted data tables (A and B), in table A, 3 first columns are genomic coordinates. I like to extract some specific rows from A table but based on some common columns/values of B table.

For example: First, I would like to match column 6 of A table and column 1 of B table, then if there is a 1 value in the third column of B table, select those rows (from A table) which have the same value (first match) in the fourth column of A and B tables and the coordinates before. But if there is a - 1 value in the third column of B table, select those rows (from A table) which have the same value (last match) in the fourth column of A and B tables and the coordinates after.

Input A:

17  50094737    50094898    1   ENST00000007708 ENSG00000005882 
17  50096132    50096286    2   ENST00000007708 ENSG00000005882 
17  50097423    50097564    3   ENST00000007708,ENST00000503176,ENST00000614357 ENSG00000005882
17  50105371    50105442    3   ENST00000007708,ENST00000503176,ENST00000614357 ENSG00000005882
17  50109957    50111058    1   ENST00000007708 ENSG00000005882 
17  50109957    50111368    2   ENST00000614357 ENSG00000005882 
17  50109957    50112152    1   ENST00000503176 ENSG00000005882 
8   22987417    22987563    2   ENST00000519685 ENSG00000008853 
8   22999579    23000105    1   ENST00000251822 ENSG00000008853 
8   23004425    23004626    2   ENST00000251822,ENST00000519685 ENSG00000008853
8   23005372    23005475    2   ENST00000251822,ENST00000519685 ENSG00000008853
8   23006728    23007746    2   ENST00000251822,ENST00000519685 ENSG00000008853
8   23015638    23015743    2   ENST00000251822,ENST00000519685 ENSG00000008853
8   23017252    23020199    1   ENST00000251822 ENSG00000008853 
X   119539386   119539789   1   ENST00000644802 ENSG00000018610 
X   119541328   119541420   2   ENST00000320339,ENST00000644802 ENSG00000018610
X   119544353   119544491   2   ENST00000320339,ENST00000644802 ENSG00000018610
X   119560268   119560385   2   ENST00000320339,ENST00000644802 ENSG00000018610
X   119565232   119565401   1   ENST00000644802 ENSG00000018610 
10  14518560    14521306    1   ENST00000181796 ENSG00000065809 
10  14521158    14521306    1   ENST00000479731 ENSG00000065809 
10  14521869    14522019    8    ENST00000181796,ENST00000378458,ENST00000378467,ENST00000378470,ENST00000468747,ENST00000478076,ENST00000479731,ENST00000622567    ENSG00000065809
10  14530332    14530515    8    ENST00000181796,ENST00000378458,ENST00000378467,ENST00000378470,ENST00000468747,ENST00000478076,ENST00000479731,ENST00000622567    ENSG00000065809
10  14553322    14553387    2   ENST00000378458,ENST00000378467 ENSG00000065809
10  14571763    14572189    2   ENST00000378458,ENST00000622567 ENSG00000065809
10  14572229    14572314    1   ENST00000479731 ENSG00000065809 
10  14667634    14667691    1   ENST00000181796 ENSG00000065809 
10  14774253    14774897    1   ENST00000181796 ENSG00000065809 

Input B:

ENSG00000005882 PDK2     1  3
ENSG00000008853 RHOBTB2  1  2
ENSG00000018610 CXorf56 -1  2
ENSG00000065809 FAM107B -1  8

Desire Output:

17  50094737    50094898    1   ENST00000007708 ENSG00000005882 
17  50096132    50096286    2   ENST00000007708 ENSG00000005882 
17  50097423    50097564    3   ENST00000007708,ENST00000503176,ENST00000614357 ENSG00000005882
8   22987417    22987563    2   ENST00000519685 ENSG00000008853 
X   119560268   119560385   2   ENST00000320339,ENST00000644802 ENSG00000018610
X   119565232   119565401   1   ENST00000644802 ENSG00000018610 
10  14530332    14530515    8   ENST00000181796,ENST00000378458,ENST00000378467,ENST00000378470,ENST00000468747,ENST00000478076,ENST00000479731,ENST00000622567 ENSG00000065809
10  14553322    14553387    2   ENST00000378458,ENST00000378467 ENSG00000065809
10  14571763    14572189    2   ENST00000378458,ENST00000622567 ENSG00000065809
10  14572229    14572314    1   ENST00000479731 ENSG00000065809 
10  14667634    14667691    1   ENST00000181796 ENSG00000065809 
10  14774253    14774897    1   ENST00000181796 ENSG00000065809 

I have tried with dyplr and ifelse but I couldn`t get what I want.

Thanks a lot in advance for any possible solution!