/* Copyright (C) 2010 Tony Garnock-Jones. All rights reserved. */

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <stdint.h>
#include <stddef.h>

#include <assert.h>

#include <ucontext.h>

#include "cmsg_private.h"
#include "harness.h"
#include "ref.h"
#include "sexp.h"
#include "hashtable.h"
#include "node.h"
#include "subscription.h"

typedef struct fanout_extension_t_ {
  sexp_t *name;
  hashtable_t subscriptions;
} fanout_extension_t;

static sexp_t *fanout_extend(node_t *n, sexp_t *args) {
  if ((sexp_length(args) == 1) && sexp_stringp(sexp_head(args))) {
    cmsg_bytes_t name = sexp_data(sexp_head(args));
    fanout_extension_t *f = calloc(1, sizeof(*f));
    f->name = INCREF(sexp_head(args));
    init_hashtable(&f->subscriptions, 5, NULL, (void (*)(void *)) free_subscription);

    n->extension = f;
    return bind_node(name, n) ? NULL : sexp_cstring("bind failed");
  } else {
    return sexp_cstring("invalid args");
  }
}

static void fanout_destructor(node_t *n) {
  fanout_extension_t *f = n->extension;
  if (f != NULL) { /* can be NULL if fanout_extend was given invalid args */
    DECREF(f->name, sexp_destructor);
    destroy_hashtable(&f->subscriptions);
    free(f);
  }
}

struct delivery_context {
  fanout_extension_t *f;
  sexp_t *body;
};

static void send_to_sub(void *contextv, cmsg_bytes_t key, void *subv) {
  struct delivery_context *context = contextv;
  subscription_t *sub = subv;
  send_to_subscription(&context->f->subscriptions, sub, context->body);
}

static void fanout_handle_message(node_t *n, sexp_t *m) {
  fanout_extension_t *f = n->extension;

  size_t msglen = sexp_length(m);
  sexp_t *args;
  cmsg_bytes_t selector;

  if (msglen == 0 || !sexp_stringp(sexp_head(m))) {
    warn("Invalid message in fanout\n");
    return;
  }

  selector = sexp_data(sexp_head(m));
  args = sexp_tail(m);

  if ((msglen == 4) && !cmsg_bytes_cmp(selector, cmsg_cstring_bytes("post"))) {
    struct delivery_context context;
    context.f = f;
    context.body = sexp_listref(args, 1);
    hashtable_foreach(&f->subscriptions, send_to_sub, &context);
    return;
  }

  if ((msglen == 6) && !cmsg_bytes_cmp(selector, cmsg_cstring_bytes("subscribe"))) {
    handle_subscribe_message(&f->subscriptions, args);
    return;
  }

  if ((msglen == 2) && !cmsg_bytes_cmp(selector, cmsg_cstring_bytes("unsubscribe"))) {
    handle_unsubscribe_message(&f->subscriptions, args);
    return;
  }

  warn("Message not understood in fanout; selector <<%.*s>>, length %u\n",
       selector.len, selector.bytes,
       msglen);
}

static node_class_t fanout_class = {
  .name = "fanout",
  .extend = fanout_extend,
  .destroy = fanout_destructor,
  .handle_message = fanout_handle_message
};

void init_fanout(void) {
  register_node_class(&fanout_class);
}