package ch.usi.inf.sp.cfg;


import java.util.stream.Collectors;
import java.util.stream.StreamSupport;

public class ControlFlowGraphRenderer {
    private static final String INDENTATION = "    ";
    private final StringBuilder code = new StringBuilder();
    private int indentationLevel = 0;

    private static String nodeIdentifier(final BasicBlock bb, final String graphId) {
        // as the basic block ID is negative for the entry and exit node, and negative numbers contain
        // a dash symbol, we need to quote the identifier to make a syntactically correct DOT file
        return String.format("\"%sbb%d\"", graphId, bb.getId());
    }

    private static String nodeStyle(final BasicBlock bb, final String label) {
        if (bb.getInEdges().isEmpty()) {
            return "[shape=circle,label=\"e\",xlabel=\"" + label + "\"]";
        } else if (bb.getOutEdges().isEmpty()) {
            return "[shape=circle,label=\"x\"]";
        } else {
            return "[label=\"" + bb.getId() + "|{" +
                    StreamSupport.stream(bb.getInstructions().spliterator(), false)
                            .collect(Collectors.joining("|"))
                    + "}\"]";
        }
    }

    public static String renderControlFlowGraph(final String label, final ControlFlowGraph cfg) {
        return new ControlFlowGraphRenderer().render(label, cfg);
    }

    private void line(String line) {
        code.append(INDENTATION.repeat(indentationLevel)).append(line).append('\n');
    }

    private String render(final String desiredLabel, final ControlFlowGraph graph) {
        final String label = desiredLabel.replaceAll("\\W+", "");

        line("digraph " + label + " {");
        code.append('\n');
        indentationLevel++;

        line("node [shape=record]");
        for (final BasicBlock bb : graph.getNodes()) {
            line(nodeIdentifier(bb, label) + " " + nodeStyle(bb, label));
        }
        code.append('\n');

        for (var e : graph.getEdges()) {
            final String l = e.getLabel();
            final String suffix = l == null || l.isBlank() ? "" : (" [label=\"" + e.getLabel() + "\"]");

            line(nodeIdentifier(e.getFrom(), label) + " -> " + nodeIdentifier(e.getTo(), label) + suffix);
        }
        indentationLevel--;
        line("}");

        return code.toString();
    }
}