GST ON CONSTRUCTION (WORKS CONTRACTOR)

Dear All,

Suppose a contractor provides construction & repairing service of house (like B2c ,our own building ) and commercial buildings (like B2B, to pvt company or government, registered person)

He provides service in two ways .

1.Either provide lumpsum quote to client and  he himself purchases material and provides labour then he is eligible to get input tax credit paid on materials like cement, bricks and steel etc.(biling amount also includes labour charges )

2.if only provides only labour service to client and client himself makes the purchase of material then he (contractor) is eligible for other input tax credit?

Rate of gst on construction service and suppose he provides service to registered in GST (B2B) then purchaser can cailm the input tax credit?

Kindly guide me in this regard and thanks in advance.