package midend.llvm.instr;

import midend.llvm.type.IrArrayType;
import midend.llvm.type.IrPointerType;
import midend.llvm.type.IrType;
import midend.llvm.value.IrValue;

public class GepInstr extends IrInstr {
    public GepInstr(IrValue pointer, IrValue offset, String name) {
        super(new IrPointerType(getTargetType(pointer)), name, IrInstrType.GEP);
        addUse(pointer);
        addUse(offset);
    }

    public IrValue getPointer() {
        return getUse(0);
    }

    public IrValue getOffset() {
        return getUse(1);
    }

    public String toString() {
        IrValue pointer = this.getPointer();
        IrValue offset = this.getOffset();

        IrPointerType pointerType = (IrPointerType) pointer.getType();
        IrType targetType = pointerType.getPointeeType();

        if (targetType instanceof IrArrayType arrayType) {
            return getName() + " = getelementptr inbounds " +
                    arrayType + ", " +
                    pointerType + " " +
                    pointer.getName() + ", i32 0, " +
                    offset.getType() + " " +
                    offset.getName();
        } else {
            return getName() + " = getelementptr inbounds " +
                    targetType + ", " +
                    pointerType + " " +
                    pointer.getName() + ", " +
                    offset.getType() + " " +
                    offset.getName();   
        }
    }

    public static IrType getTargetType(IrValue pointer) {
        IrType targetType = ((IrPointerType) pointer.getType()).getPointeeType();
        if (targetType instanceof IrArrayType arrayType) {
            return arrayType.getElementType();
        } else if (targetType instanceof IrPointerType pointerType) {
            return pointerType.getPointeeType();
        } else {
            return targetType;
        }
    }
}