/*

 * Copyright © 2010 Codethink Limited

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * This library 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

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this library; if not, see <http://www.gnu.org/licenses/>.

 *

 * Author: Ryan Lortie <desrt@desrt.ca>

 */

#include "gvdb-builder.h"

#include "gvdb-format.h"

#include <glib.h>

#include <fcntl.h>

#if !defined(G_OS_WIN32) || !defined(_MSC_VER)

#include <unistd.h>

#endif

#include <string.h>

struct _GvdbItem

{

  gchar *key;

  guint32 hash_value;

  guint32_le assigned_index;

  GvdbItem *parent;

  GvdbItem *sibling;

  GvdbItem *next;

  /* one of:

   * this:

   */

  GVariant *value;

  /* this: */

  GHashTable *table;

  /* or this: */

  GvdbItem *child;

};

static void

gvdb_item_free (gpointer data)

{

  GvdbItem *item = data;

  g_free (item->key);

  if (item->value)

    g_variant_unref (item->value);

  if (item->table)

    g_hash_table_unref (item->table);

  g_slice_free (GvdbItem, item);

}

GHashTable *

gvdb_hash_table_new (GHashTable  *parent,

                     const gchar *name_in_parent)

{

  GHashTable *table;

  table = g_hash_table_new_full (g_str_hash, g_str_equal,

                                 g_free, gvdb_item_free);

  if (parent)

    {

      GvdbItem *item;

      item = gvdb_hash_table_insert (parent, name_in_parent);

      gvdb_item_set_hash_table (item, table);

    }

  return table;

}

static guint32

djb_hash (const gchar *key)

{

  guint32 hash_value = 5381;

  while (*key)

    hash_value = hash_value * 33 + *(signed char *)key++;

  return hash_value;

}

GvdbItem *

gvdb_hash_table_insert (GHashTable  *table,

                        const gchar *key)

{

  GvdbItem *item;

  item = g_slice_new0 (GvdbItem);

  item->key = g_strdup (key);

  item->hash_value = djb_hash (key);

  g_hash_table_insert (table, g_strdup (key), item);

  return item;

}

void

gvdb_hash_table_insert_string (GHashTable  *table,

                               const gchar *key,

                               const gchar *value)

{

  GvdbItem *item;

  item = gvdb_hash_table_insert (table, key);

  gvdb_item_set_value (item, g_variant_new_string (value));

}

void

gvdb_item_set_value (GvdbItem *item,

                     GVariant *value)

{

  g_return_if_fail (!item->value && !item->table && !item->child);

  item->value = g_variant_ref_sink (value);

}

void

gvdb_item_set_hash_table (GvdbItem   *item,

                          GHashTable *table)

{

  g_return_if_fail (!item->value && !item->table && !item->child);

  item->table = g_hash_table_ref (table);

}

void

gvdb_item_set_parent (GvdbItem *item,

                      GvdbItem *parent)

{

  GvdbItem **node;

  g_return_if_fail (g_str_has_prefix (item->key, parent->key));

  g_return_if_fail (!parent->value && !parent->table);

  g_return_if_fail (!item->parent && !item->sibling);

  for (node = &parent->child; *node; node = &(*node)->sibling)

    if (strcmp ((*node)->key, item->key) > 0)

      break;

  item->parent = parent;

  item->sibling = *node;

  *node = item;

}

typedef struct

{

  GvdbItem **buckets;

  gint n_buckets;

} HashTable;

static HashTable *

hash_table_new (gint n_buckets)

{

  HashTable *table;

  table = g_slice_new (HashTable);

  table->buckets = g_new0 (GvdbItem *, n_buckets);

  table->n_buckets = n_buckets;

  return table;

}

static void

hash_table_free (HashTable *table)

{

  g_free (table->buckets);

  g_slice_free (HashTable, table);

}

static void

hash_table_insert (gpointer key,

                   gpointer value,

                   gpointer data)

{

  guint32 hash_value, bucket;

  HashTable *table = data;

  GvdbItem *item = value;

  hash_value = djb_hash (key);

  bucket = hash_value % table->n_buckets;

  item->next = table->buckets[bucket];

  table->buckets[bucket] = item;

}

static guint32_le

item_to_index (GvdbItem *item)

{

  if (item != NULL)

    return item->assigned_index;

  return guint32_to_le (-1u);

}

typedef struct

{

  GQueue *chunks;

  guint64 offset;

  gboolean byteswap;

} FileBuilder;

typedef struct

{

  gsize offset;

  gsize size;

  gpointer data;

} FileChunk;

static gpointer

file_builder_allocate (FileBuilder         *fb,

                       guint                alignment,

                       gsize                size,

                       struct gvdb_pointer *pointer)

{

  FileChunk *chunk;

  if (size == 0)

    return NULL;

  fb->offset += (-fb->offset) & (alignment - 1);

  chunk = g_slice_new (FileChunk);

  chunk->offset = fb->offset;

  chunk->size = size;

  chunk->data = g_malloc (size);

  pointer->start = guint32_to_le (fb->offset);

  fb->offset += size;

  pointer->end = guint32_to_le (fb->offset);

  g_queue_push_tail (fb->chunks, chunk);

  return chunk->data;

}

static void

file_builder_add_value (FileBuilder         *fb,

                        GVariant            *value,

                        struct gvdb_pointer *pointer)

{

  GVariant *variant, *normal;

  gpointer data;

  gsize size;

  if (fb->byteswap)

    {

      value = g_variant_byteswap (value);

      variant = g_variant_new_variant (value);

      g_variant_unref (value);

    }

  else

    variant = g_variant_new_variant (value);

  normal = g_variant_get_normal_form (variant);

  g_variant_unref (variant);

  size = g_variant_get_size (normal);

  data = file_builder_allocate (fb, 8, size, pointer);

  g_variant_store (normal, data);

  g_variant_unref (normal);

}

static void

file_builder_add_string (FileBuilder *fb,

                         const gchar *string,

                         guint32_le  *start,

                         guint16_le  *size)

{

  FileChunk *chunk;

  gsize length;

  length = strlen (string);

  chunk = g_slice_new (FileChunk);

  chunk->offset = fb->offset;

  chunk->size = length;

  chunk->data = g_malloc (length);

  if (length != 0)

    memcpy (chunk->data, string, length);

  *start = guint32_to_le (fb->offset);

  *size = guint16_to_le (length);

  fb->offset += length;

  g_queue_push_tail (fb->chunks, chunk);

}

static void

file_builder_allocate_for_hash (FileBuilder            *fb,

                                gsize                   n_buckets,

                                gsize                   n_items,

                                guint                   bloom_shift,

                                gsize                   n_bloom_words,

                                guint32_le            **bloom_filter,

                                guint32_le            **hash_buckets,

                                struct gvdb_hash_item **hash_items,

                                struct gvdb_pointer    *pointer)

{

  guint32_le bloom_hdr, table_hdr;

  guchar *data;

  gsize size;

  g_assert (n_bloom_words < (1u << 27));

  bloom_hdr = guint32_to_le (bloom_shift << 27 | n_bloom_words);

  table_hdr = guint32_to_le (n_buckets);

  size = sizeof bloom_hdr + sizeof table_hdr +

         n_bloom_words * sizeof (guint32_le) +

         n_buckets     * sizeof (guint32_le) +

         n_items       * sizeof (struct gvdb_hash_item);

  data = file_builder_allocate (fb, 4, size, pointer);

#define chunk(s) (size -= (s), data += (s), data - (s))

  memcpy (chunk (sizeof bloom_hdr), &bloom_hdr, sizeof bloom_hdr);

  memcpy (chunk (sizeof table_hdr), &table_hdr, sizeof table_hdr);

  *bloom_filter = (guint32_le *) chunk (n_bloom_words * sizeof (guint32_le));

  *hash_buckets = (guint32_le *) chunk (n_buckets * sizeof (guint32_le));

  *hash_items = (struct gvdb_hash_item *) chunk (n_items *

                  sizeof (struct gvdb_hash_item));

  g_assert (size == 0);

#undef chunk

  memset (*bloom_filter, 0, n_bloom_words * sizeof (guint32_le));

}

static void

file_builder_add_hash (FileBuilder         *fb,

                       GHashTable          *table,

                       struct gvdb_pointer *pointer)

{

  guint32_le *buckets, *bloom_filter;

  struct gvdb_hash_item *items;

  HashTable *mytable;

  GvdbItem *item;

  guint32 index;

  gint bucket;

  mytable = hash_table_new (g_hash_table_size (table));

  g_hash_table_foreach (table, hash_table_insert, mytable);

  index = 0;

  for (bucket = 0; bucket < mytable->n_buckets; bucket++)

    for (item = mytable->buckets[bucket]; item; item = item->next)

      item->assigned_index = guint32_to_le (index++);

  file_builder_allocate_for_hash (fb, mytable->n_buckets, index, 5, 0,

                                  &bloom_filter, &buckets, &items, pointer);

  index = 0;

  for (bucket = 0; bucket < mytable->n_buckets; bucket++)

    {

      buckets[bucket] = guint32_to_le (index);

      for (item = mytable->buckets[bucket]; item; item = item->next)

        {

          struct gvdb_hash_item *entry = items++;

          const gchar *basename;

          g_assert (index == guint32_from_le (item->assigned_index));

          entry->hash_value = guint32_to_le (item->hash_value);

          entry->parent = item_to_index (item->parent);

          entry->unused = 0;

          if (item->parent != NULL)

            basename = item->key + strlen (item->parent->key);

          else

            basename = item->key;

          file_builder_add_string (fb, basename,

                                   &entry->key_start,

                                   &entry->key_size);

          if (item->value != NULL)

            {

              g_assert (item->child == NULL && item->table == NULL);

              file_builder_add_value (fb, item->value, &entry->value.pointer);

              entry->type = 'v';

            }

          if (item->child != NULL)

            {

              guint32 children = 0, i = 0;

              guint32_le *offsets;

              GvdbItem *child;

              g_assert (item->table == NULL);

              for (child = item->child; child; child = child->sibling)

                children++;

              offsets = file_builder_allocate (fb, 4, 4 * children,

                                               &entry->value.pointer);

              entry->type = 'L';

              for (child = item->child; child; child = child->sibling)

                offsets[i++] = child->assigned_index;

              g_assert (children == i);

            }

          if (item->table != NULL)

            {

              entry->type = 'H';

              file_builder_add_hash (fb, item->table, &entry->value.pointer);

            }

          index++;

        }

    }

  hash_table_free (mytable);

}

static FileBuilder *

file_builder_new (gboolean byteswap)

{

  FileBuilder *builder;

  builder = g_slice_new (FileBuilder);

  builder->chunks = g_queue_new ();

  builder->offset = sizeof (struct gvdb_header);

  builder->byteswap = byteswap;

  return builder;

}

static GString *

file_builder_serialise (FileBuilder          *fb,

                        struct gvdb_pointer   root)

{

  struct gvdb_header header = { { 0, }, };

  GString *result;

  if (fb->byteswap)

    {

      header.signature[0] = GVDB_SWAPPED_SIGNATURE0;

      header.signature[1] = GVDB_SWAPPED_SIGNATURE1;

    }

  else

    {

      header.signature[0] = GVDB_SIGNATURE0;

      header.signature[1] = GVDB_SIGNATURE1;

    }

  result = g_string_new (NULL);

  header.root = root;

  g_string_append_len (result, (gpointer) &header, sizeof header);

  while (!g_queue_is_empty (fb->chunks))

    {

      FileChunk *chunk = g_queue_pop_head (fb->chunks);

      if (result->len != chunk->offset)

        {

          gchar zero[8] = { 0, };

          g_assert (chunk->offset > result->len);

          g_assert (chunk->offset - result->len < 8);

          g_string_append_len (result, zero, chunk->offset - result->len);

          g_assert (result->len == chunk->offset);

        }

      g_string_append_len (result, chunk->data, chunk->size);

      g_free (chunk->data);

      g_slice_free (FileChunk, chunk);

    }

  g_queue_free (fb->chunks);

  g_slice_free (FileBuilder, fb);

  return result;

}

gboolean

gvdb_table_write_contents (GHashTable   *table,

                           const gchar  *filename,

                           gboolean      byteswap,

                           GError      **error)

{

  struct gvdb_pointer root;

  gboolean status;

  FileBuilder *fb;

  GString *str;

  fb = file_builder_new (byteswap);

  file_builder_add_hash (fb, table, &root);

  str = file_builder_serialise (fb, root);

  status = g_file_set_contents (filename, str->str, str->len, error);

  g_string_free (str, TRUE);

  return status;

}