// ── Pure C code generation — zero-DOM, flat DFA model ─────────────────
//
// Every block is a C label.  Every flow edge is a `goto label;`.
// There is zero nesting: no if/else chains, no branch-analysis, no
// shared-block computation.  Decisions become `if (cond) goto yes;
// goto no;`.  Error handling becomes `if (call != 0) goto err;
// goto ok;`.
//
// Block interface:
//   { id: string,
//     generateOwnCode(): string,   // C code for this one block
//     generateFlowCode?(): string, // flow-control (gotos).  If absent,
//                                  // CodeGen walks wcNextFlow instead.
//     wcNextFlow?: [{toElement: block}],
//     nextFlow?:   [{toElement: block}] }

(function () {
  "use strict";

  var CodeGen = {};

  /**
   * Emits a complete C program as a flat sequence of labelled blocks
   * connected by gotos.  Each block is emitted once (DFS order); already-
   * visited blocks become `goto label;` stubs.
   *
   * @param {Object} entry  the first block (e.g. START)
   * @returns {string}
   */
  CodeGen.emitFlat = function (entry) {
    var visited = new Set();
    var parts = [];

    function emit(block) {
      if (visited.has(block)) {
        parts.push("  goto " + block.id + ";\n");
        return;
      }
      visited.add(block);
      parts.push("\n" + block.id + ":");

      var own = block.generateOwnCode();
      if (own) parts.push(own);

      // Flow control: custom generateFlowCode, or auto from wcNextFlow
      var flow = block.wcNextFlow || block.nextFlow || [];
      var fc = "";
      if (typeof block.generateFlowCode === "function") {
        fc = block.generateFlowCode();
      } else {
        for (var i = 0; i < flow.length; i++) {
          var t = flow[i].toElement;
          if (t) fc += "  goto " + t.id + ";\n";
        }
      }
      if (fc) parts.push("\n" + fc);

      // Recurse into successors (visited blocks are skipped at top)
      for (var i = 0; i < flow.length; i++) {
        var t = flow[i].toElement;
        if (t) emit(t);
      }
    }

    emit(entry);
    return parts.join("");
  };

  /**
   * Assembles a complete C source file.
   */
  CodeGen.generateCFile = function (entryBlock, includes, declarations) {
    var lines = ["// --- WiseCode\u00ae ---"];
    for (var i = 0; i < includes.length; i++) lines.push(includes[i]);
    lines.push("");
    lines.push("int main() {");
    if (declarations) lines.push(declarations);
    lines.push(CodeGen.emitFlat(entryBlock));
    lines.push("}");
    lines.push("// --- END ---");
    return lines.join("\n");
  };

  // ── Export ──────────────────────────────────────────────────────────
  if (typeof module !== "undefined" && module.exports) {
    module.exports = CodeGen;
  }
  if (typeof window !== "undefined") {
    window.CodeGen = CodeGen;
  }
})();