package ch.usi.inf.sp.cfg;

import ch.usi.inf.sp.graph.DiGraph;


public final class ControlFlowGraph extends DiGraph<BasicBlock, ControlFlowEdge> {

    private BasicBlock entry;
    private BasicBlock exit;


    public ControlFlowGraph() {
        entry = new BasicBlock(-1);
        addNode(entry);
        exit = new BasicBlock(-2);
        addNode(exit);
    }

    private final void checkContains(BasicBlock block, String name) {
        if (!getNodes().contains(block)) {
            throw new IllegalStateException("Control flow graph does not contain the given " + name + " block.");
        }
    }

    public ControlFlowEdge addEntryEdge(BasicBlock firstBlock) {
        if (entry.getOutEdges().size() > 0) {
            throw new IllegalStateException("Control flow graph already has an entry edge. It can only have one.");
        }
        checkContains(firstBlock, "firstBlock");
        ControlFlowEdge edge = new ControlFlowEdge("");
        addEdge(edge);
        connect(entry, edge, firstBlock);
        return edge;
    }

    public ControlFlowEdge addExitEdge(BasicBlock returnBlock) {
        checkContains(returnBlock, "returnBlock");
        ControlFlowEdge edge = new ControlFlowEdge("");
        addEdge(edge);
        connect(returnBlock, edge, exit);
        return edge;
    }

    public ControlFlowEdge addFallthroughEdge(BasicBlock fromBlock, BasicBlock toBlock) {
        checkContains(fromBlock, "fromBlock");
        checkContains(toBlock, "toBlock");
        ControlFlowEdge edge = new ControlFlowEdge("");
        addEdge(edge);
        connect(fromBlock, edge, toBlock);
        return edge;
    }

    public ControlFlowEdge addBranchTakenEdge(BasicBlock fromBlock, BasicBlock toBlock) {
        checkContains(fromBlock, "fromBlock");
        checkContains(toBlock, "toBlock");
        ControlFlowEdge edge = new ControlFlowEdge("T");
        addEdge(edge);
        connect(fromBlock, edge, toBlock);
        return edge;
    }

    public ControlFlowEdge addCaseEdge(BasicBlock fromBlock, BasicBlock toBlock, int key) {
        checkContains(fromBlock, "fromBlock");
        checkContains(toBlock, "toBlock");
        ControlFlowEdge edge = new ControlFlowEdge("" + key);
        addEdge(edge);
        connect(fromBlock, edge, toBlock);
        return edge;
    }

    public ControlFlowEdge addDefaultEdge(BasicBlock fromBlock, BasicBlock toBlock) {
        checkContains(fromBlock, "fromBlock");
        checkContains(toBlock, "toBlock");
        ControlFlowEdge edge = new ControlFlowEdge("default");
        addEdge(edge);
        connect(fromBlock, edge, toBlock);
        return edge;
    }

    public BasicBlock getEntry() {
        return entry;
    }

    public BasicBlock getExit() {
        return exit;
    }

    public String toString() {
        final StringBuffer sb = new StringBuffer("digraph CFG {\n");
        for (final BasicBlock node : getNodes()) {
            if (node==entry) {
                sb.append("  " + node + " [shape=circle,style=filled,label=e]\n");
            } else if (node==exit) {
                    sb.append("  " + node + " [shape=circle,style=filled,label=x]\n");
            } else {
                sb.append("  " + node + " [shape=rectangle]\n");
            }
        }
        for (final ControlFlowEdge edge : getEdges()) {
            if (edge.getLabel().length()>0) {
                sb.append("  " + edge + " [label=" + edge.getLabel() + "]\n");
            } else {
                sb.append("  " + edge + "\n");
            }
        }
        sb.append("}\n");
        return sb.toString();
    }

}