/*

Copyright 2020 Google LLC

Use of this source code is governed by a BSD-style

license that can be found in the LICENSE file or at

https://developers.google.com/open-source/licenses/bsd

*/

#include "writer.h"

#include "system.h"

#include "block.h"

#include "constants.h"

#include "record.h"

#include "reftable.h"

#include "tree.h"

static struct reftable_block_stats *

writer_reftable_block_stats(struct reftable_writer *w, byte typ)

{

  switch (typ) {

  case 'r':

    return &w->stats.ref_stats;

  case 'o':

    return &w->stats.obj_stats;

  case 'i':

    return &w->stats.idx_stats;

  case 'g':

    return &w->stats.log_stats;

  }

  assert(false);

  return NULL;

}

/* write data, queuing the padding for the next write. Returns negative for

 * error. */

static int padded_write(struct reftable_writer *w, byte *data, size_t len,

      int padding)

{

  int n = 0;

  if (w->pending_padding > 0) {

    byte *zeroed = reftable_calloc(w->pending_padding);

    int n = w->write(w->write_arg, zeroed, w->pending_padding);

    if (n < 0) {

      return n;

    }

    w->pending_padding = 0;

    reftable_free(zeroed);

  }

  w->pending_padding = padding;

  n = w->write(w->write_arg, data, len);

  if (n < 0) {

    return n;

  }

  n += padding;

  return 0;

}

static void options_set_defaults(struct reftable_write_options *opts)

{

  if (opts->restart_interval == 0) {

    opts->restart_interval = 16;

  }

  if (opts->hash_id == 0) {

    opts->hash_id = SHA1_ID;

  }

  if (opts->block_size == 0) {

    opts->block_size = DEFAULT_BLOCK_SIZE;

  }

}

static int writer_version(struct reftable_writer *w)

{

  return (w->opts.hash_id == 0 || w->opts.hash_id == SHA1_ID) ? 1 : 2;

}

static int writer_write_header(struct reftable_writer *w, byte *dest)

{

  memcpy((char *)dest, "REFT", 4);

  dest[4] = writer_version(w);

  put_be24(dest + 5, w->opts.block_size);

  put_be64(dest + 8, w->min_update_index);

  put_be64(dest + 16, w->max_update_index);

  if (writer_version(w) == 2) {

    put_be32(dest + 24, w->opts.hash_id);

  }

  return header_size(writer_version(w));

}

static void writer_reinit_block_writer(struct reftable_writer *w, byte typ)

{

  int block_start = 0;

  if (w->next == 0) {

    block_start = header_size(writer_version(w));

  }

  block_writer_init(&w->block_writer_data, typ, w->block,

        w->opts.block_size, block_start,

        hash_size(w->opts.hash_id));

  w->block_writer = &w->block_writer_data;

  w->block_writer->restart_interval = w->opts.restart_interval;

}

struct reftable_writer *

reftable_new_writer(int (*writer_func)(void *, byte *, size_t),

        void *writer_arg, struct reftable_write_options *opts)

{

  struct reftable_writer *wp =

    reftable_calloc(sizeof(struct reftable_writer));

  options_set_defaults(opts);

  if (opts->block_size >= (1 << 24)) {

    /* TODO - error return? */

    abort();

  }

  wp->block = reftable_calloc(opts->block_size);

  wp->write = writer_func;

  wp->write_arg = writer_arg;

  wp->opts = *opts;

  writer_reinit_block_writer(wp, BLOCK_TYPE_REF);

  return wp;

}

void reftable_writer_set_limits(struct reftable_writer *w, uint64_t min,

        uint64_t max)

{

  w->min_update_index = min;

  w->max_update_index = max;

}

void reftable_writer_free(struct reftable_writer *w)

{

  reftable_free(w->block);

  reftable_free(w);

}

struct obj_index_tree_node {

  struct slice hash;

  uint64_t *offsets;

  int offset_len;

  int offset_cap;

};

static int obj_index_tree_node_compare(const void *a, const void *b)

{

  return slice_compare(((const struct obj_index_tree_node *)a)->hash,

           ((const struct obj_index_tree_node *)b)->hash);

}

static void writer_index_hash(struct reftable_writer *w, struct slice hash)

{

  uint64_t off = w->next;

  struct obj_index_tree_node want = { .hash = hash };

  struct tree_node *node = tree_search(&want, &w->obj_index_tree,

               &obj_index_tree_node_compare, 0);

  struct obj_index_tree_node *key = NULL;

  if (node == NULL) {

    key = reftable_calloc(sizeof(struct obj_index_tree_node));

    slice_copy(&key->hash, hash);

    tree_search((void *)key, &w->obj_index_tree,

          &obj_index_tree_node_compare, 1);

  } else {

    key = node->key;

  }

  if (key->offset_len > 0 && key->offsets[key->offset_len - 1] == off) {

    return;

  }

  if (key->offset_len == key->offset_cap) {

    key->offset_cap = 2 * key->offset_cap + 1;

    key->offsets = reftable_realloc(

      key->offsets, sizeof(uint64_t) * key->offset_cap);

  }

  key->offsets[key->offset_len++] = off;

}

static int writer_add_record(struct reftable_writer *w, struct record rec)

{

  int result = -1;

  struct slice key = { 0 };

  int err = 0;

  record_key(rec, &key);

  if (slice_compare(w->last_key, key) >= 0) {

    goto exit;

  }

  slice_copy(&w->last_key, key);

  if (w->block_writer == NULL) {

    writer_reinit_block_writer(w, record_type(rec));

  }

  assert(block_writer_type(w->block_writer) == record_type(rec));

  if (block_writer_add(w->block_writer, rec) == 0) {

    result = 0;

    goto exit;

  }

  err = writer_flush_block(w);

  if (err < 0) {

    result = err;

    goto exit;

  }

  writer_reinit_block_writer(w, record_type(rec));

  err = block_writer_add(w->block_writer, rec);

  if (err < 0) {

    result = err;

    goto exit;

  }

  result = 0;

exit:

  slice_clear(&key);

  return result;

}

int reftable_writer_add_ref(struct reftable_writer *w,

          struct reftable_ref_record *ref)

{

  struct record rec = { 0 };

  struct reftable_ref_record copy = *ref;

  int err = 0;

  if (ref->ref_name == NULL) {

    return REFTABLE_API_ERROR;

  }

  if (ref->update_index < w->min_update_index ||

      ref->update_index > w->max_update_index) {

    return REFTABLE_API_ERROR;

  }

  record_from_ref(&rec, &copy);

  copy.update_index -= w->min_update_index;

  err = writer_add_record(w, rec);

  if (err < 0) {

    return err;

  }

  if (!w->opts.skip_index_objects && ref->value != NULL) {

    struct slice h = {

      .buf = ref->value,

      .len = hash_size(w->opts.hash_id),

    };

    writer_index_hash(w, h);

  }

  if (!w->opts.skip_index_objects && ref->target_value != NULL) {

    struct slice h = {

      .buf = ref->target_value,

      .len = hash_size(w->opts.hash_id),

    };

    writer_index_hash(w, h);

  }

  return 0;

}

int reftable_writer_add_refs(struct reftable_writer *w,

           struct reftable_ref_record *refs, int n)

{

  int err = 0;

  int i = 0;

  QSORT(refs, n, reftable_ref_record_compare_name);

  for (i = 0; err == 0 && i < n; i++) {

    err = reftable_writer_add_ref(w, &refs[i]);

  }

  return err;

}

int reftable_writer_add_log(struct reftable_writer *w,

          struct reftable_log_record *log)

{

  if (log->ref_name == NULL) {

    return REFTABLE_API_ERROR;

  }

  if (w->block_writer != NULL &&

      block_writer_type(w->block_writer) == BLOCK_TYPE_REF) {

    int err = writer_finish_public_section(w);

    if (err < 0) {

      return err;

    }

  }

  w->next -= w->pending_padding;

  w->pending_padding = 0;

  {

    struct record rec = { 0 };

    int err;

    record_from_log(&rec, log);

    err = writer_add_record(w, rec);

    return err;

  }

}

int reftable_writer_add_logs(struct reftable_writer *w,

           struct reftable_log_record *logs, int n)

{

  int err = 0;

  int i = 0;

  QSORT(logs, n, reftable_log_record_compare_key);

  for (i = 0; err == 0 && i < n; i++) {

    err = reftable_writer_add_log(w, &logs[i]);

  }

  return err;

}

static int writer_finish_section(struct reftable_writer *w)

{

  byte typ = block_writer_type(w->block_writer);

  uint64_t index_start = 0;

  int max_level = 0;

  int threshold = w->opts.unpadded ? 1 : 3;

  int before_blocks = w->stats.idx_stats.blocks;

  int err = writer_flush_block(w);

  int i = 0;

  if (err < 0) {

    return err;

  }

  while (w->index_len > threshold) {

    struct index_record *idx = NULL;

    int idx_len = 0;

    max_level++;

    index_start = w->next;

    writer_reinit_block_writer(w, BLOCK_TYPE_INDEX);

    idx = w->index;

    idx_len = w->index_len;

    w->index = NULL;

    w->index_len = 0;

    w->index_cap = 0;

    for (i = 0; i < idx_len; i++) {

      struct record rec = { 0 };

      record_from_index(&rec, idx + i);

      if (block_writer_add(w->block_writer, rec) == 0) {

        continue;

      }

      {

        int err = writer_flush_block(w);

        if (err < 0) {

          return err;

        }

      }

      writer_reinit_block_writer(w, BLOCK_TYPE_INDEX);

      err = block_writer_add(w->block_writer, rec);

      if (err != 0) {

        /* write into fresh block should always succeed

         */

        abort();

      }

    }

    for (i = 0; i < idx_len; i++) {

      slice_clear(&idx[i].last_key);

    }

    reftable_free(idx);

  }

  writer_clear_index(w);

  err = writer_flush_block(w);

  if (err < 0) {

    return err;

  }

  {

    struct reftable_block_stats *bstats =

      writer_reftable_block_stats(w, typ);

    bstats->index_blocks =

      w->stats.idx_stats.blocks - before_blocks;

    bstats->index_offset = index_start;

    bstats->max_index_level = max_level;

  }

  /* Reinit lastKey, as the next section can start with any key. */

  w->last_key.len = 0;

  return 0;

}

struct common_prefix_arg {

  struct slice *last;

  int max;

};

static void update_common(void *void_arg, void *key)

{

  struct common_prefix_arg *arg = (struct common_prefix_arg *)void_arg;

  struct obj_index_tree_node *entry = (struct obj_index_tree_node *)key;

  if (arg->last != NULL) {

    int n = common_prefix_size(entry->hash, *arg->last);

    if (n > arg->max) {

      arg->max = n;

    }

  }

  arg->last = &entry->hash;

}

struct write_record_arg {

  struct reftable_writer *w;

  int err;

};

static void write_object_record(void *void_arg, void *key)

{

  struct write_record_arg *arg = (struct write_record_arg *)void_arg;

  struct obj_index_tree_node *entry = (struct obj_index_tree_node *)key;

  struct obj_record obj_rec = {

    .hash_prefix = entry->hash.buf,

    .hash_prefix_len = arg->w->stats.object_id_len,

    .offsets = entry->offsets,

    .offset_len = entry->offset_len,

  };

  struct record rec = { 0 };

  if (arg->err < 0) {

    goto exit;

  }

  record_from_obj(&rec, &obj_rec);

  arg->err = block_writer_add(arg->w->block_writer, rec);

  if (arg->err == 0) {

    goto exit;

  }

  arg->err = writer_flush_block(arg->w);

  if (arg->err < 0) {

    goto exit;

  }

  writer_reinit_block_writer(arg->w, BLOCK_TYPE_OBJ);

  arg->err = block_writer_add(arg->w->block_writer, rec);

  if (arg->err == 0) {

    goto exit;

  }

  obj_rec.offset_len = 0;

  arg->err = block_writer_add(arg->w->block_writer, rec);

  /* Should be able to write into a fresh block. */

  assert(arg->err == 0);

exit:;

}

static void object_record_free(void *void_arg, void *key)

{

  struct obj_index_tree_node *entry = (struct obj_index_tree_node *)key;

  FREE_AND_NULL(entry->offsets);

  slice_clear(&entry->hash);

  reftable_free(entry);

}

static int writer_dump_object_index(struct reftable_writer *w)

{

  struct write_record_arg closure = { .w = w };

  struct common_prefix_arg common = { 0 };

  if (w->obj_index_tree != NULL) {

    infix_walk(w->obj_index_tree, &update_common, &common);

  }

  w->stats.object_id_len = common.max + 1;

  writer_reinit_block_writer(w, BLOCK_TYPE_OBJ);

  if (w->obj_index_tree != NULL) {

    infix_walk(w->obj_index_tree, &write_object_record, &closure);

  }

  if (closure.err < 0) {

    return closure.err;

  }

  return writer_finish_section(w);

}

int writer_finish_public_section(struct reftable_writer *w)

{

  byte typ = 0;

  int err = 0;

  if (w->block_writer == NULL) {

    return 0;

  }

  typ = block_writer_type(w->block_writer);

  err = writer_finish_section(w);

  if (err < 0) {

    return err;

  }

  if (typ == BLOCK_TYPE_REF && !w->opts.skip_index_objects &&

      w->stats.ref_stats.index_blocks > 0) {

    err = writer_dump_object_index(w);

    if (err < 0) {

      return err;

    }

  }

  if (w->obj_index_tree != NULL) {

    infix_walk(w->obj_index_tree, &object_record_free, NULL);

    tree_free(w->obj_index_tree);

    w->obj_index_tree = NULL;

  }

  w->block_writer = NULL;

  return 0;

}

int reftable_writer_close(struct reftable_writer *w)

{

  byte footer[72];

  byte *p = footer;

  int err = writer_finish_public_section(w);

  int empty_table = w->next == 0;

  if (err != 0) {

    goto exit;

  }

  w->pending_padding = 0;

  if (empty_table) {

    /* Empty tables need a header anyway. */

    byte header[28];

    int n = writer_write_header(w, header);

    err = padded_write(w, header, n, 0);

    if (err < 0) {

      goto exit;

    }

  }

  p += writer_write_header(w, footer);

  put_be64(p, w->stats.ref_stats.index_offset);

  p += 8;

  put_be64(p, (w->stats.obj_stats.offset) << 5 | w->stats.object_id_len);

  p += 8;

  put_be64(p, w->stats.obj_stats.index_offset);

  p += 8;

  put_be64(p, w->stats.log_stats.offset);

  p += 8;

  put_be64(p, w->stats.log_stats.index_offset);

  p += 8;

  put_be32(p, crc32(0, footer, p - footer));

  p += 4;

  err = padded_write(w, footer, footer_size(writer_version(w)), 0);

  if (err < 0) {

    goto exit;

  }

  if (empty_table) {

    err = REFTABLE_EMPTY_TABLE_ERROR;

    goto exit;

  }

exit:

  /* free up memory. */

  block_writer_clear(&w->block_writer_data);

  writer_clear_index(w);

  slice_clear(&w->last_key);

  return err;

}

void writer_clear_index(struct reftable_writer *w)

{

  int i = 0;

  for (i = 0; i < w->index_len; i++) {

    slice_clear(&w->index[i].last_key);

  }

  FREE_AND_NULL(w->index);

  w->index_len = 0;

  w->index_cap = 0;

}

const int debug = 0;

static int writer_flush_nonempty_block(struct reftable_writer *w)

{

  byte typ = block_writer_type(w->block_writer);

  struct reftable_block_stats *bstats =

    writer_reftable_block_stats(w, typ);

  uint64_t block_typ_off = (bstats->blocks == 0) ? w->next : 0;

  int raw_bytes = block_writer_finish(w->block_writer);

  int padding = 0;

  int err = 0;

  if (raw_bytes < 0) {

    return raw_bytes;

  }

  if (!w->opts.unpadded && typ != BLOCK_TYPE_LOG) {

    padding = w->opts.block_size - raw_bytes;

  }

  if (block_typ_off > 0) {

    bstats->offset = block_typ_off;

  }

  bstats->entries += w->block_writer->entries;

  bstats->restarts += w->block_writer->restart_len;

  bstats->blocks++;

  w->stats.blocks++;

  if (debug) {

    fprintf(stderr, "block %c off %" PRIu64 " sz %d (%d)\n", typ,

      w->next, raw_bytes,

      get_be24(w->block + w->block_writer->header_off + 1));

  }

  if (w->next == 0) {

    writer_write_header(w, w->block);

  }

  err = padded_write(w, w->block, raw_bytes, padding);

  if (err < 0) {

    return err;

  }

  if (w->index_cap == w->index_len) {

    w->index_cap = 2 * w->index_cap + 1;

    w->index = reftable_realloc(

      w->index, sizeof(struct index_record) * w->index_cap);

  }

  {

    struct index_record ir = {

      .offset = w->next,

    };

    slice_copy(&ir.last_key, w->block_writer->last_key);

    w->index[w->index_len] = ir;

  }

  w->index_len++;

  w->next += padding + raw_bytes;

  w->block_writer = NULL;

  return 0;

}

int writer_flush_block(struct reftable_writer *w)

{

  if (w->block_writer == NULL) {

    return 0;

  }

  if (w->block_writer->entries == 0) {

    return 0;

  }

  return writer_flush_nonempty_block(w);

}

const struct reftable_stats *writer_stats(struct reftable_writer *w)

{

  return &w->stats;

}