/*
 * CLI graph handling
 *
 * --
 * Copyright (C) 2016 Cumulus Networks, Inc.
 * Copyright (C) 1997, 98, 99 Kunihiro Ishiguro
 * Copyright (C) 2013 by Open Source Routing.
 * Copyright (C) 2013 by Internet Systems Consortium, Inc. ("ISC")
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <zebra.h>

#include "command_graph.h"

DECLARE_MTYPE(CMD_TOKEN_DATA)

DEFINE_MTYPE_STATIC(LIB, CMD_TOKENS, "Command Tokens")
DEFINE_MTYPE_STATIC(LIB, CMD_DESC,   "Command Token Text")
DEFINE_MTYPE_STATIC(LIB, CMD_TEXT,   "Command Token Help")
DEFINE_MTYPE(       LIB, CMD_ARG,    "Command Argument")
DEFINE_MTYPE_STATIC(LIB, CMD_VAR,    "Command Argument Name")

struct cmd_token *
cmd_token_new (enum cmd_token_type type, u_char attr,
               const char *text, const char *desc)
{
  struct cmd_token *token = XCALLOC (MTYPE_CMD_TOKENS, sizeof (struct cmd_token));
  token->type = type;
  token->attr = attr;
  token->text = text ? XSTRDUP (MTYPE_CMD_TEXT, text) : NULL;
  token->desc = desc ? XSTRDUP (MTYPE_CMD_DESC, desc) : NULL;
  token->refcnt = 1;
  token->arg  = NULL;
  token->allowrepeat = false;
  token->varname = NULL;

  return token;
}

void
cmd_token_del (struct cmd_token *token)
{
  if (!token) return;

  XFREE (MTYPE_CMD_TEXT, token->text);
  XFREE (MTYPE_CMD_DESC, token->desc);
  XFREE (MTYPE_CMD_ARG, token->arg);
  XFREE (MTYPE_CMD_VAR, token->varname);

  XFREE (MTYPE_CMD_TOKENS, token);
}

struct cmd_token *
cmd_token_dup (struct cmd_token *token)
{
  struct cmd_token *copy = cmd_token_new (token->type, token->attr, NULL, NULL);
  copy->max   = token->max;
  copy->min   = token->min;
  copy->text  = token->text ? XSTRDUP (MTYPE_CMD_TEXT, token->text) : NULL;
  copy->desc  = token->desc ? XSTRDUP (MTYPE_CMD_DESC, token->desc) : NULL;
  copy->arg   = token->arg  ? XSTRDUP (MTYPE_CMD_ARG, token->arg) : NULL;
  copy->varname = token->varname ? XSTRDUP (MTYPE_CMD_VAR, token->varname) : NULL;

  return copy;
}

void cmd_token_varname_set(struct cmd_token *token, const char *varname)
{
  XFREE (MTYPE_CMD_VAR, token->varname);
  token->varname = varname ? XSTRDUP (MTYPE_CMD_VAR, varname) : NULL;
}

static bool
cmd_nodes_link (struct graph_node *from, struct graph_node *to)
{
  for (size_t i = 0; i < vector_active (from->to); i++)
    if (vector_slot (from->to, i) == to)
      return true;
  return false;
}

static bool cmd_nodes_equal (struct graph_node *ga, struct graph_node *gb);

/* returns a single node to be excluded as "next" from iteration
 * - for JOIN_TKN, never continue back to the FORK_TKN
 * - in all other cases, don't try the node itself (in case of "...")
 */
static inline struct graph_node *
cmd_loopstop(struct graph_node *gn)
{
  struct cmd_token *tok = gn->data;
  if (tok->type == JOIN_TKN)
    return tok->forkjoin;
  else
    return gn;
}

static bool
cmd_subgraph_equal (struct graph_node *ga, struct graph_node *gb,
                    struct graph_node *a_join)
{
  size_t i, j;
  struct graph_node *a_fork, *b_fork;
  a_fork = cmd_loopstop (ga);
  b_fork = cmd_loopstop (gb);

  if (vector_active (ga->to) != vector_active (gb->to))
    return false;
  for (i = 0; i < vector_active (ga->to); i++)
    {
      struct graph_node *cga = vector_slot (ga->to, i);

      for (j = 0; j < vector_active (gb->to); j++)
        {
          struct graph_node *cgb = vector_slot (gb->to, i);

          if (cga == a_fork && cgb != b_fork)
            continue;
          if (cga == a_fork && cgb == b_fork)
            break;

          if (cmd_nodes_equal (cga, cgb))
            {
              if (cga == a_join)
                break;
              if (cmd_subgraph_equal (cga, cgb, a_join))
                break;
            }
        }
      if (j == vector_active (gb->to))
        return false;
    }
  return true;
}

/* deep compare -- for FORK_TKN, the entire subgraph is compared.
 * this is what's needed since we're not currently trying to partially
 * merge subgraphs */
static bool
cmd_nodes_equal (struct graph_node *ga, struct graph_node *gb)
{
  struct cmd_token *a = ga->data, *b = gb->data;

  if (a->type != b->type || a->allowrepeat != b->allowrepeat)
    return false;
  if (a->type < SPECIAL_TKN && strcmp (a->text, b->text))
    return false;
  /* one a ..., the other not. */
  if (cmd_nodes_link (ga, ga) != cmd_nodes_link (gb, gb))
    return false;

  switch (a->type)
    {
    case RANGE_TKN:
      return a->min == b->min && a->max == b->max;

    case FORK_TKN:
      /* one is keywords, the other just option or selector ... */
      if (cmd_nodes_link (a->forkjoin, ga) != cmd_nodes_link (b->forkjoin, gb))
        return false;
      if (cmd_nodes_link (ga, a->forkjoin) != cmd_nodes_link (gb, b->forkjoin))
        return false;
      return cmd_subgraph_equal (ga, gb, a->forkjoin);

    default:
      return true;
    }
}

static void
cmd_fork_bump_attr (struct graph_node *gn, struct graph_node *join,
                    u_char attr)
{
  size_t i;
  struct cmd_token *tok = gn->data;
  struct graph_node *stop = cmd_loopstop (gn);

  tok->attr = attr;
  for (i = 0; i < vector_active (gn->to); i++)
    {
      struct graph_node *next = vector_slot (gn->to, i);
      if (next == stop || next == join)
        continue;
      cmd_fork_bump_attr (next, join, attr);
    }
}

/* move an entire subtree from the temporary graph resulting from
 * parse() into the permanent graph for the command node.
 *
 * this touches rather deeply into the graph code unfortunately.
 */
static void
cmd_reparent_tree (struct graph *fromgraph, struct graph *tograph,
                   struct graph_node *node)
{
  struct graph_node *stop = cmd_loopstop (node);
  size_t i;

  for (i = 0; i < vector_active (fromgraph->nodes); i++)
    if (vector_slot (fromgraph->nodes, i) == node)
      {
        /* agressive iteration punching through subgraphs - may hit some
         * nodes twice.  reparent only if found on old graph */
        vector_unset (fromgraph->nodes, i);
        vector_set (tograph->nodes, node);
        break;
      }

  for (i = 0; i < vector_active (node->to); i++)
    {
      struct graph_node *next = vector_slot (node->to, i);
      if (next != stop)
        cmd_reparent_tree (fromgraph, tograph, next);
    }
}

static void
cmd_free_recur (struct graph *graph, struct graph_node *node,
                struct graph_node *stop)
{
  struct graph_node *next, *nstop;

  for (size_t i = vector_active (node->to); i; i--)
    {
      next = vector_slot (node->to, i - 1);
      if (next == stop)
        continue;
      nstop = cmd_loopstop (next);
      if (nstop != next)
        cmd_free_recur (graph, next, nstop);
      cmd_free_recur (graph, nstop, stop);
    }
  graph_delete_node (graph, node);
}

static void
cmd_free_node (struct graph *graph, struct graph_node *node)
{
  struct cmd_token *tok = node->data;
  if (tok->type == JOIN_TKN)
    cmd_free_recur (graph, tok->forkjoin, node);
  graph_delete_node (graph, node);
}

/* recursive graph merge.  call with
 *   old ~= new
 * (which holds true for old == START_TKN, new == START_TKN)
 */
static void
cmd_merge_nodes (struct graph *oldgraph, struct graph *newgraph,
                 struct graph_node *old, struct graph_node *new,
                 int direction)
{
  struct cmd_token *tok;
  struct graph_node *old_skip, *new_skip;
  old_skip = cmd_loopstop (old);
  new_skip = cmd_loopstop (new);

  assert (direction == 1 || direction == -1);

  tok = old->data;
  tok->refcnt += direction;

  size_t j, i;
  for (j = 0; j < vector_active (new->to); j++)
    {
      struct graph_node *cnew = vector_slot (new->to, j);
      if (cnew == new_skip)
        continue;

      for (i = 0; i < vector_active (old->to); i++)
        {
          struct graph_node *cold = vector_slot (old->to, i);
          if (cold == old_skip)
            continue;

          if (cmd_nodes_equal (cold, cnew))
            {
              struct cmd_token *told = cold->data, *tnew = cnew->data;

              if (told->type == END_TKN)
                {
                  if (direction < 0)
                    {
                      graph_delete_node (oldgraph, vector_slot (cold->to, 0));
                      graph_delete_node (oldgraph, cold);
                    }
                  else
                    /* force no-match handling to install END_TKN */
                    i = vector_active (old->to);
                  break;
                }

              /* the entire fork compared as equal, we continue after it. */
              if (told->type == FORK_TKN)
                {
                  if (tnew->attr < told->attr && direction > 0)
                    cmd_fork_bump_attr (cold, told->forkjoin, tnew->attr);
                  /* XXX: no reverse bump on uninstall */
                  told = (cold = told->forkjoin)->data;
                  tnew = (cnew = tnew->forkjoin)->data;
                }
              if (tnew->attr < told->attr)
                told->attr = tnew->attr;

              cmd_merge_nodes (oldgraph, newgraph, cold, cnew, direction);
              break;
            }
        }
      /* nothing found => add new to old */
      if (i == vector_active (old->to) && direction > 0)
        {
          assert (vector_count (cnew->from) ==
                          cmd_nodes_link (cnew, cnew) ? 2 : 1);
          graph_remove_edge (new, cnew);

          cmd_reparent_tree (newgraph, oldgraph, cnew);

          graph_add_edge (old, cnew);
        }
    }

  if (!tok->refcnt)
    cmd_free_node (oldgraph, old);
}

void
cmd_graph_merge (struct graph *old, struct graph *new, int direction)
{
  assert (vector_active (old->nodes) >= 1);
  assert (vector_active (new->nodes) >= 1);

  cmd_merge_nodes (old, new,
                   vector_slot (old->nodes, 0), vector_slot (new->nodes, 0),
                   direction);
}