module ddbus.router;

import ddbus.thin;
import ddbus.c_lib;
import ddbus.util;
import std.string;
import std.typecons;
import core.memory;
import std.array;
import std.algorithm;
import std.format;

struct MessagePattern {
  string path;
  string iface;
  string method;
  bool signal;

  this(Message msg) {
    path = msg.path();
    iface = msg.iface();
    method = msg.member();
    signal = (msg.type() == MessageType.Signal);
  }

  this(string path, string iface, string method, bool signal = false) {
    this.path = path;
    this.iface = iface;
    this.method = method;
    this.signal = signal;
  }

  size_t toHash() const @safe nothrow {
    size_t hash = 0;
    auto stringHash = &(typeid(path).getHash);
    hash += stringHash(&path);
    hash += stringHash(&iface);
    hash += stringHash(&method);
    hash += (signal?1:0);
    return hash;
  }

  bool opEquals(ref const this s) const @safe pure nothrow {
    return (path == s.path) && (iface == s.iface) && (method == s.method) && (signal == s.signal);
  }
}

unittest {
  import dunit.toolkit;
  auto msg = Message("org.example.test", "/test","org.example.testing","testMethod");
  auto patt= new MessagePattern(msg);
  patt.assertEqual(patt);
  patt.signal.assertFalse();
  patt.path.assertEqual("/test");
}

struct MessageHandler {
  alias HandlerFunc = void delegate(Message call, Connection conn);
  HandlerFunc func;
  string[] argSig;
  string[] retSig;
}

class MessageRouter {
  MessageHandler[MessagePattern] callTable;

  bool handle(Message msg, Connection conn) {
    MessageType type = msg.type();
    if(type != MessageType.Call && type != MessageType.Signal)
      return false;
    auto pattern = MessagePattern(msg);
    // import std.stdio; debug writeln("Handling ", pattern);

    if(pattern.iface == "org.freedesktop.DBus.Introspectable" &&
      pattern.method == "Introspect" && !pattern.signal) {
      handleIntrospect(pattern.path, msg, conn);
      return true;
    }

    MessageHandler* handler = (pattern in callTable);
    if(handler is null) return false;

    // Check for matching argument types
    version(DDBusNoChecking) {

    } else {
      if(!equal(join(handler.argSig), msg.signature())) {
        return false;
      }
    }

    handler.func(msg,conn);
    return true;
  }

  void setHandler(Ret, Args...)(MessagePattern patt, Ret delegate(Args) handler) {
    void handlerWrapper(Message call, Connection conn) {
      Tuple!Args args = call.readTuple!(Tuple!Args)();
      auto retMsg = call.createReturn();
      static if(!is(Ret == void)) {
        Ret ret = handler(args.expand);
        retMsg.build(ret);
      } else {
        handler(args.expand);
      }
      if(!patt.signal)
        conn.send(retMsg);
    }
    static string[] args = typeSigArr!Args;
    static if(is(Ret==void)) {
      static string[] ret = [];
    } else {
      static string[] ret = [typeSig!Ret];
    }
    MessageHandler handleStruct = {func: &handlerWrapper, argSig: args, retSig: ret};
    callTable[patt] = handleStruct;
  }

  static string introspectHeader = `<!DOCTYPE node PUBLIC "-//freedesktop//DTD D-BUS Object Introspection 1.0//EN" "http://www.freedesktop.org/standards/dbus/1.0/introspect.dtd">
<node name="%s">`;

  string introspectXML(string path) {
    auto methods = callTable.byKey().filter!(a => (a.path == path) && !a.signal)().array()
      // .schwartzSort!((a) => a.iface, "a<b")();
      .sort!((a,b) => a.iface < b.iface)();
    auto ifaces = methods.groupBy();
    auto app = appender!string;
    formattedWrite(app,introspectHeader,path);
    foreach(iface; ifaces) {
      formattedWrite(app,`<interface name="%s">`,iface.front.iface);
      foreach(methodPatt; iface.array()) {
        formattedWrite(app,`<method name="%s">`,methodPatt.method);
        auto handler = callTable[methodPatt];
        foreach(arg; handler.argSig) {
          formattedWrite(app,`<arg type="%s" direction="in"/>`,arg);
        }
        foreach(arg; handler.retSig) {
          formattedWrite(app,`<arg type="%s" direction="out"/>`,arg);
        }
        app.put("</method>");
      }
      app.put("</interface>");
    }

    string childPath = path;
    if(!childPath.endsWith("/")) {
      childPath ~= "/";
    }
    auto children = callTable.byKey().filter!(a => (a.path.startsWith(childPath)) && !a.signal)()
      .map!((s) => s.path.chompPrefix(childPath))
      .map!((s) => s.splitter('/').front)
      .array().sort().uniq();
    foreach(child; children) {
      formattedWrite(app,`<node name="%s"/>`,child);
    }

    app.put("</node>");
    return app.data;
  }

  void handleIntrospect(string path, Message call, Connection conn) {
    auto retMsg = call.createReturn();
    retMsg.build(introspectXML(path));
    conn.sendBlocking(retMsg);
  }
}

extern(C) private DBusHandlerResult filterFunc(DBusConnection *dConn, DBusMessage *dMsg, void *routerP) {
  MessageRouter router = cast(MessageRouter)routerP;
  dbus_message_ref(dMsg);
  Message msg = Message(dMsg);
  dbus_connection_ref(dConn);
  Connection conn = Connection(dConn);
  bool handled = router.handle(msg, conn);
  if(handled) {
    return DBusHandlerResult.DBUS_HANDLER_RESULT_HANDLED;
  } else {
    return DBusHandlerResult.DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
  }
}

extern(C) private void unrootUserData(void *userdata) {
  GC.removeRoot(userdata);
}

void registerRouter(Connection conn, MessageRouter router) {
  void *routerP = cast(void*)router;
  GC.addRoot(routerP);
  dbus_connection_add_filter(conn.conn, &filterFunc, routerP, &unrootUserData);
}

unittest{
  import dunit.toolkit;
  auto router = new MessageRouter();
  // set up test messages
  MessagePattern patt = MessagePattern("/root","ca.thume.test","test");
  router.setHandler!(int,int)(patt,(int p) {return 6;});
  patt = MessagePattern("/root","ca.thume.tester","lolwut");
  router.setHandler!(void,int,string)(patt,(int p, string p2) {});
  patt = MessagePattern("/root/wat","ca.thume.tester","lolwut");
  router.setHandler!(int,int)(patt,(int p) {return 6;});
  patt = MessagePattern("/troll","ca.thume.tester","wow");
  router.setHandler!(void)(patt,{return;});

  // TODO: these tests rely on nondeterministic hash map ordering
  static string introspectResult = `<!DOCTYPE node PUBLIC "-//freedesktop//DTD D-BUS Object Introspection 1.0//EN" "http://www.freedesktop.org/standards/dbus/1.0/introspect.dtd">
<node name="/root"><interface name="ca.thume.test"><method name="test"><arg type="i" direction="in"/><arg type="i" direction="out"/></method></interface><interface name="ca.thume.tester"><method name="lolwut"><arg type="i" direction="in"/><arg type="s" direction="in"/></method></interface><node name="wat"/></node>`;
  router.introspectXML("/root").assertEqual(introspectResult);
  router.introspectXML("/").assertEndsWith(`<node name="/"><node name="root"/><node name="troll"/></node>`);
}