package midend.llvm.instr;

import java.util.ArrayList;
import java.util.StringJoiner;

import midend.llvm.type.IrType;
import midend.llvm.value.IrBasicBlock;
import midend.llvm.value.IrValue;

public class PhiInstr extends IrInstr {
    private ArrayList<IrBasicBlock> predBBs;

    public PhiInstr(IrType type, IrBasicBlock bblock, String name) {
        super(type, name, IrInstrType.PHI);
        this.setBBlock(bblock);
        this.predBBs = new ArrayList<>(bblock.getPreds());
        for (IrBasicBlock bb : predBBs) {
            this.addUse(null);
        }
    }

    public ArrayList<IrBasicBlock> getPredBBs() {
        return predBBs;
    }

    public void setValueForPred(IrBasicBlock pred, IrValue value) {
        int index = predBBs.indexOf(pred);
        this.setUse(index, value);
    }

    public void deletePred(IrBasicBlock pred) {
        int index = predBBs.indexOf(pred);
        if (index != -1) {
            predBBs.remove(index);
            this.deleteUse(index);
        }
    }

    public void replacePred(IrBasicBlock oldPred, IrBasicBlock newPred) {
        //TODO: whether the function is needed    
    }

    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append(getName());
        sb.append(" = phi ");
        sb.append(getType().toString());
        for (int i = 0; i < this.predBBs.size(); i++) {
            sb.append("[ ");
            sb.append(getUse(i).getName());
            sb.append(", %");
            sb.append(this.predBBs.get(i).getName());
            sb.append(" ]");
        }
        return sb.toString();
    }
}