'use strict';

var c       = require('./constants');
var utils   = require('./utils');
var trees   = require('./trees');
var adler32 = require('./adler32');
var crc32   = require('./crc32');

var Z_NULL = c.Z_NULL;

var MAX_WBITS = 15;
/* 32K LZ77 window */
var DEF_MEM_LEVEL = 8;

var MIN_MATCH = 3;
var MAX_MATCH = 258;
var MIN_LOOKAHEAD = (MAX_MATCH + MIN_MATCH + 1);

var PRESET_DICT = 0x20;

var INIT_STATE = 42;
var EXTRA_STATE = 69;
var NAME_STATE = 73;
var COMMENT_STATE = 91;
var HCRC_STATE = 103;
var BUSY_STATE = 113;
var FINISH_STATE = 666;

var BS_NEED_MORE      = 1; /* block not completed, need more input or more output */
var BS_BLOCK_DONE     = 2; /* block flush performed */
var BS_FINISH_STARTED = 3; /* finish started, need only more output at next deflate */
var BS_FINISH_DONE    = 4; /* finish done, accept no more input or output */

var OS_CODE = 0x03; // Unix :) . Don't detect, use this default.

function rank (f) {
  return ((f) << 1) - ((f) > 4 ? 9 : 0);
}

/* =========================================================================
 * Flush as much pending output as possible. All deflate() output goes
 * through this function so some applications may wish to modify it
 * to avoid allocating a large strm->next_out buffer and copying into it.
 * (See also read_buf()).
 */
function flush_pending(strm) {
  var s = strm.state;

  //_tr_flush_bits(s);
  var len = s.pending;
  if (len > strm.avail_out) {
    len = strm.avail_out;
  }
  if (len === 0) { return; }

  utils.arraySet(strm.next_out, s.pending_buf, s.pending_out, len, strm.next_out_index);
  strm.next_out_index += len;
  s.pending_out += len;
  strm.total_out += len;
  strm.avail_out -= len;
  s.pending -= len;
  if (s.pending === 0) {
    s.pending_out = 0;
  }
}

function flush_block_only (s, last) {
  trees._tr_flush_block(s, (s.block_start >= 0 ? s.block_start : Z_NULL), s.strstart - s.block_start, last);
  s.block_start = s.strstart;
  flush_pending(s.strm);
}

function update_hash (s, h, c) {
  return (((h) << s.hash_shift) ^ (c)) & s.hash_mask;
}

function put_byte(s, b) {
  s.pending_buf[s.pending++] = b;
}

/* =========================================================================
 * Put a short in the pending buffer. The 16-bit value is put in MSB order.
 * IN assertion: the stream state is correct and there is enough room in
 * pending_buf.
 */
function putShortMSB(s, b) {
//  put_byte(s, (Byte)(b >> 8));
//  put_byte(s, (Byte)(b & 0xff));
  s.pending_buf[s.pending++] = (b >>> 8) & 0xff;
  s.pending_buf[s.pending++] = b & 0xff;
}

/* ===========================================================================
 * Read a new buffer from the current input stream, update the adler32
 * and total number of bytes read.  All deflate() input goes through
 * this function so some applications may wish to modify it to avoid
 * allocating a large strm->next_in buffer and copying from it.
 * (See also flush_pending()).
 */
function read_buf(strm, buf, start, size) {
  var len = strm.avail_in;

  if (len > size) { len = size; }
  if (len === 0) { return 0; }

  strm.avail_in -= len;

  utils.arraySet(buf, strm.next_in, strm.next_in_index, len, start);
  if (strm.state.wrap === 1) {
    strm.adler = adler32(strm.adler, buf, len, start);
  }

  else if (strm.state.wrap === 2) {
    strm.adler = crc32(strm.adler, buf, len, start);
  }

  strm.next_in_index += len;
  strm.total_in += len;

  return len;
}

/* ===========================================================================
 * Set match_start to the longest match starting at the given string and
 * return its length. Matches shorter or equal to prev_length are discarded,
 * in which case the result is equal to prev_length and match_start is
 * garbage.
 * IN assertions: cur_match is the head of the hash chain for the current
 *   string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
 * OUT assertion: the match length is not greater than s->lookahead.
 */
//function longest_match(s, cur_match) {
//
//}

/* ===========================================================================
 * Fill the window when the lookahead becomes insufficient.
 * Updates strstart and lookahead.
 *
 * IN assertion: lookahead < MIN_LOOKAHEAD
 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
 *    At least one byte has been read, or avail_in == 0; reads are
 *    performed for at least two bytes (required for the zip translate_eol
 *    option -- not supported here).
 */
function fill_window(s) {
  var _w_size = s.w_size;
  var p = 0, n = 0, m = 0, more, str;

  //Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead");

  do {
    more = s.window_size - s.lookahead - s.strstart;

    if (more === 0 && s.strstart === 0 && s.lookahead === 0) {
      more = _w_size;

    } else if (more === -1) {
      /* Very unlikely, but possible on 16 bit machine if
       * strstart == 0 && lookahead == 1 (input done a byte at time)
       */
      more--;
    }


    /* If the window is almost full and there is insufficient lookahead,
     * move the upper half to the lower one to make room in the upper half.
     */
    if (s.strstart >= _w_size + (_w_size - MIN_LOOKAHEAD)) {

      utils.arraySet(s.window, s.window, _w_size, _w_size, 0);
      s.match_start -= _w_size;
      s.strstart -= _w_size;
      /* we now have strstart >= MAX_DIST */
      s.block_start -= _w_size;

      /* Slide the hash table (could be avoided with 32 bit values
       at the expense of memory usage). We slide even when level == 0
       to keep the hash table consistent if we switch back to level > 0
       later. (Using level 0 permanently is not an optimal usage of
       zlib, so we don't care about this pathological case.)
       */

      // TODO: check if shortlinks to `s.head` & `s.prev` improve speed.

      n = s.hash_size;
      p = n;
      do {
        m = s.head[--p];
        s.head[p] = m >= _w_size ? m - _w_size : 0;
      } while (--n);

      n = _w_size;
      p = n;
      do {
        m = s.prev[--p];
        s.prev[p] = m >= _w_size ? m - _w_size : 0;
        /* If n is not on any hash chain, prev[n] is garbage but
         * its value will never be used.
         */
      } while (--n);

      more += _w_size;
    }
    if (s.strm.avail_in === 0) {
      break;
    }

    /* If there was no sliding:
     *    strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
     *    more == window_size - lookahead - strstart
     * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
     * => more >= window_size - 2*WSIZE + 2
     * In the BIG_MEM or MMAP case (not yet supported),
     *   window_size == input_size + MIN_LOOKAHEAD  &&
     *   strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
     * Otherwise, window_size == 2*WSIZE so more >= 2.
     * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
     */
    //Assert(more >= 2, "more < 2");
    n = read_buf(s.strm, s.window, s.strstart + s.lookahead, more);
    s.lookahead += n;

    /* Initialize the hash value now that we have some input: */
    if (s.lookahead + s.insert >= MIN_MATCH) {
      str = s.strstart - s.insert;
      s.ins_h = s.window[str];
      s.ins_h = update_hash(s, s.ins_h, s.window[str + 1]);
//#if MIN_MATCH != 3
//        Call update_hash() MIN_MATCH-3 more times
//#endif
      while (s.insert) {
        s.ins_h = update_hash(s, s.ins_h, s.window[str + MIN_MATCH - 1]);
        s.prev[str & s.w_mask] = s.head[s.ins_h];
        s.head[s.ins_h] = str;
        str++;
        s.insert--;
        if (s.lookahead + s.insert < MIN_MATCH) {
          break;
        }
      }
    }
    /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
     * but this is not important since only literal bytes will be emitted.
     */

  } while (s.lookahead < MIN_LOOKAHEAD && s.strm.avail_in !== 0);

  /* If the WIN_INIT bytes after the end of the current data have never been
   * written, then zero those bytes in order to avoid memory check reports of
   * the use of uninitialized (or uninitialised as Julian writes) bytes by
   * the longest match routines.  Update the high water mark for the next
   * time through here.  WIN_INIT is set to MAX_MATCH since the longest match
   * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead.
   */
//  if (s.high_water < s.window_size) {
//    var curr = s.strstart + s.lookahead;
//    var init = 0;
//
//    if (s.high_water < curr) {
//      /* Previous high water mark below current data -- zero WIN_INIT
//       * bytes or up to end of window, whichever is less.
//       */
//      init = s.window_size - curr;
//      if (init > WIN_INIT)
//        init = WIN_INIT;
//      zmemzero(s->window + curr, (unsigned)init);
//      s->high_water = curr + init;
//    }
//    else if (s->high_water < (ulg)curr + WIN_INIT) {
//      /* High water mark at or above current data, but below current data
//       * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up
//       * to end of window, whichever is less.
//       */
//      init = (ulg)curr + WIN_INIT - s->high_water;
//      if (init > s->window_size - s->high_water)
//        init = s->window_size - s->high_water;
//      zmemzero(s->window + s->high_water, (unsigned)init);
//      s->high_water += init;
//    }
//  }
//
//  Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD,
//    "not enough room for search");
}

/* ===========================================================================
 * Copy without compression as much as possible from the input stream, return
 * the current block state.
 * This function does not insert new strings in the dictionary since
 * uncompressible data is probably not useful. This function is used
 * only for the level=0 compression option.
 * NOTE: this function should be optimized to avoid extra copying from
 * window to pending_buf.
 */
function deflate_stored(s, flush) {
  /* Stored blocks are limited to 0xffff bytes, pending_buf is limited
   * to pending_buf_size, and each stored block has a 5 byte header:
   */
  var max_block_size = 0xffff;

  if (max_block_size > s.pending_buf_size - 5) {
    max_block_size = s.pending_buf_size - 5;
  }

  /* Copy as much as possible from input to output: */
  for (;;) {
    /* Fill the window as much as possible: */
    if (s.lookahead <= 1) {

      //Assert(s->strstart < s->w_size+MAX_DIST(s) ||
      //  s->block_start >= (long)s->w_size, "slide too late");
//      if (!(s.strstart < s.w_size + (s.w_size - MIN_LOOKAHEAD) ||
//        s.block_start >= s.w_size)) {
//        throw  new Error("slide too late");
//      }

      fill_window(s);
      if (s.lookahead === 0 && flush === c.Z_NO_FLUSH) {
        return BS_NEED_MORE;
      }

      if (s.lookahead === 0) {
        break;
      }
      /* flush the current block */
    }
    //Assert(s->block_start >= 0L, "block gone");
//    if (s.block_start < 0) throw new Error("block gone");

    s.strstart += s.lookahead;
    s.lookahead = 0;

    /* Emit a stored block if pending_buf will be full: */
    var max_start = s.block_start + max_block_size;

    if (s.strstart === 0 || s.strstart >= max_start) {
      /* strstart == 0 is possible when wraparound on 16-bit machine */
      s.lookahead = s.strstart - max_start;
      s.strstart = max_start;
      /*** FLUSH_BLOCK(s, 0); ***/
      flush_block_only(s, false);
      if (s.strm.avail_out === 0) {
        return BS_NEED_MORE;
      }
      /***/


    }
    /* Flush if we may have to slide, otherwise block_start may become
     * negative and the data will be gone:
     */
    if (s.strstart - s.block_start >= (s.w_size - MIN_LOOKAHEAD)) {
      /*** FLUSH_BLOCK(s, 0); ***/
      flush_block_only(s, false);
      if (s.strm.avail_out === 0) {
        return BS_NEED_MORE;
      }
      /***/
    }
  }

  s.insert = 0;

  if (flush === c.Z_FINISH) {
    /*** FLUSH_BLOCK(s, 1); ***/
    flush_block_only(s, true);
    if (s.strm.avail_out === 0) {
      return BS_FINISH_STARTED;
    }
    /***/
    return BS_FINISH_STARTED;
  }

  if (s.strstart > s.block_start) {
    /*** FLUSH_BLOCK(s, 0); ***/
    flush_block_only(s, false);
    if (s.strm.avail_out === 0) {
      return BS_NEED_MORE;
    }
    /***/
  }

  return BS_NEED_MORE;
}

/* ===========================================================================
 * Compress as much as possible from the input stream, return the current
 * block state.
 * This function does not perform lazy evaluation of matches and inserts
 * new strings in the dictionary only for unmatched strings or for short
 * matches. It is used only for the fast compression options.
 */
function deflate_fast(/*s, flush*/) {

}

/* ===========================================================================
 * Same as above, but achieves better compression. We use a lazy
 * evaluation for matches: a match is finally adopted only if there is
 * no better match at the next window position.
 */
function deflate_slow(/*s, flush*/) {

}

/* ===========================================================================
 * For Z_RLE, simply look for runs of bytes, generate matches only of distance
 * one.  Do not maintain a hash table.  (It will be regenerated if this run of
 * deflate switches away from Z_RLE.)
 */
function deflate_rle(/*s, flush*/) {

}

/* ===========================================================================
 * For Z_HUFFMAN_ONLY, do not look for matches.  Do not maintain a hash table.
 * (It will be regenerated if this run of deflate switches away from Huffman.)
 */
function deflate_huff(/*s, flush*/) {

}

var Config = function (good_length, max_lazy, nice_length, max_chain, func) {
  this.good_length = good_length;
  this.max_lazy = max_lazy;
  this.nice_length = nice_length;
  this.max_chain = max_chain;
  this.func = func;
};

var configuration_table;

configuration_table = [
  /*      good lazy nice chain */
  new Config(0, 0, 0, 0, deflate_stored),          /* 0 store only */
  new Config(4, 4, 8, 4, deflate_fast),            /* 1 max speed, no lazy matches */
  new Config(4, 5, 16, 8, deflate_fast),           /* 2 */
  new Config(4, 6, 32, 32, deflate_fast),          /* 3 */

  new Config(4, 4, 16, 16, deflate_slow),          /* 4 lazy matches */
  new Config(8, 16, 32, 32, deflate_slow),         /* 5 */
  new Config(8, 16, 128, 128, deflate_slow),       /* 6 */
  new Config(8, 32, 128, 256, deflate_slow),       /* 7 */
  new Config(32, 128, 258, 1024, deflate_slow),    /* 8 */
  new Config(32, 258, 258, 4096, deflate_slow)     /* 9 max compression */
];

/* ===========================================================================
 * Initialize the "longest match" routines for a new zlib stream
 */
function lm_init(s) {
  s.window_size = 2 * s.w_size;

  /* Set the default configuration parameters:
   */
  s.max_lazy_match = configuration_table[s.level].max_lazy;
  s.good_match = configuration_table[s.level].good_length;
  s.nice_match = configuration_table[s.level].nice_length;
  s.max_chain_length = configuration_table[s.level].max_chain;

  s.strstart = 0;
  s.block_start = 0;
  s.lookahead = 0;
  s.insert = 0;
  s.match_length = s.prev_length = MIN_MATCH - 1;
  s.match_available = 0;
  s.ins_h = 0;
}

function DeflateState() {
  // z_streamp strm;            /* pointer back to this zlib stream */
  this.status = 0;            /* as the name implies */
  // pending_buf = Z_NULL;      /* output still pending */
  this.pending_buf_size = 0;  /* size of pending_buf */
  this.pending_out = 0;       /* next pending byte to output to the stream */
  this.pending = 0;           /* nb of bytes in the pending buffer */
  this.wrap = 0;              /* bit 0 true for zlib, bit 1 true for gzip */
  this.gzhead = null;         /* gzip header information to write */
  this.gzindex = 0;           /* where in extra, name, or comment */
  this.method = c.Z_DEFLATED; /* can only be DEFLATED */
  this.last_flush = Z_NULL;   /* value of flush param for previous deflate call */

  this.w_size = 0;  /* LZ77 window size (32K by default) */
  this.w_bits = 0;  /* log2(w_size)  (8..16) */
  this.w_mask = 0;  /* w_size - 1 */

  this.window = null;
  /* Sliding window. Input bytes are read into the second half of the window,
   * and move to the first half later to keep a dictionary of at least wSize
   * bytes. With this organization, matches are limited to a distance of
   * wSize-MAX_MATCH bytes, but this ensures that IO is always
   * performed with a length multiple of the block size.
   */

  this.window_size = 0;
  /* Actual size of window: 2*wSize, except when the user input buffer
   * is directly used as sliding window.
   */

  this.prev = null;
  /* Link to older string with same hash index. To limit the size of this
   * array to 64K, this link is maintained only for the last 32K strings.
   * An index in this array is thus a window index modulo 32K.
   */

  this.head = null;   /* Heads of the hash chains or NIL. */

  this.ins_h = 0;       /* hash index of string to be inserted */
  this.hash_size = 0;   /* number of elements in hash table */
  this.hash_bits = 0;   /* log2(hash_size) */
  this.hash_mask = 0;   /* hash_size-1 */

  this.hash_shift = 0;
  /* Number of bits by which ins_h must be shifted at each input
   * step. It must be such that after MIN_MATCH steps, the oldest
   * byte no longer takes part in the hash key, that is:
   *   hash_shift * MIN_MATCH >= hash_bits
   */

  this.block_start = 0;
  /* Window position at the beginning of the current output block. Gets
   * negative when the window is moved backwards.
   */

  this.match_length = 0;      /* length of best match */
  this.prev_match = 0;        /* previous match */
  this.match_available = 1;   /* set if previous match exists */
  this.strstart = 0;          /* start of string to insert */
  this.match_start = 0;       /* start of matching string */
  this.lookahead = 0;         /* number of valid bytes ahead in window */

  this.prev_length = 0;
  /* Length of the best match at previous step. Matches not greater than this
   * are discarded. This is used in the lazy match evaluation.
   */

  this.max_chain_length = 0;
  /* To speed up deflation, hash chains are never searched beyond this
   * length.  A higher limit improves compression ratio but degrades the
   * speed.
   */

  this.max_lazy_match = 0;
  /* Attempt to find a better match only when the current match is strictly
   * smaller than this value. This mechanism is used only for compression
   * levels >= 4.
   */
  this.max_insert_length = 0;
  /* Insert new strings in the hash table only if the match length is not
   * greater than this length. This saves time but degrades compression.
   * max_insert_length is used only for compression levels <= 3.
   */

  this.level = 0;     /* compression level (1..9) */
  this.strategy = 0;  /* favor or force Huffman coding*/

  this.good_match = 0;
  /* Use a faster search when the previous match is longer than this */

  this.nice_match = 0;
  /* Stop searching when current match exceeds this */
}

function deflateResetKeep(strm) {
  strm.total_in = strm.total_out = 0;
  strm.data_type = c.Z_UNKNOWN;

  var s = strm.state;
  s.pending = 0;
  s.pending_out = 0;

  if (s.wrap < 0) {
    s.wrap = -s.wrap;
    /* was made negative by deflate(..., Z_FINISH); */
  }
  s.status = s.wrap ? INIT_STATE : BUSY_STATE;
  strm.adler = (s.wrap === 2) ?
    0  // crc32(0, Z_NULL, 0)
  :
    1; // adler32(0, Z_NULL, 0)
  s.last_flush = c.Z_NO_FLUSH;
  trees._tr_init(s);
  return c.Z_OK;
}

function deflateReset(strm) {
  var ret = deflateResetKeep(strm);
  if (ret === c.Z_OK) {
    lm_init(strm.state);
  }
  return ret;
}

function deflateInit2(strm, level, method, windowBits, memLevel, strategy) {
  if (strm === Z_NULL) {
    return c.Z_STREAM_ERROR;
  }
  var wrap = 1;

  if (level === c.Z_DEFAULT_COMPRESSION) {
    level = 6;
  }

  if (windowBits < 0) { /* suppress zlib wrapper */
    wrap = 0;
    windowBits = -windowBits;
  }

  else if (windowBits > 15) {
    wrap = 2;           /* write gzip wrapper instead */
    windowBits -= 16;
  }

  if (windowBits === 8) {
    windowBits = 9;
  }
  /* until 256-byte window bug fixed */

  var s = new DeflateState();

  strm.state = s;
  s.strm = strm;

  s.wrap = wrap;
  s.gzhead = null;
  s.w_bits = windowBits;
  s.w_size = 1 << s.w_bits;
  s.w_mask = s.w_size - 1;

  s.hash_bits = memLevel + 7;
  s.hash_size = 1 << s.hash_bits;
  s.hash_mask = s.hash_size - 1;
  s.hash_shift = (s.hash_bits + MIN_MATCH - 1) / MIN_MATCH;

  s.window = utils.arrayCreate(s.w_size * 2);
  s.head = utils.array16Create(s.hash_size);
  s.prev = utils.array16Create(s.w_size);
  // precreate & prefill head/prev arrays to optimize v8 types
  // TODO: check if we can remove it, should be inited in lm_init()
  utils.fill(s.head, 0);
  utils.fill(s.prev, 0);

  s.high_water = 0;  /* nothing written to s->window yet */

  s.lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */

  s.pending_buf_size = s.lit_bufsize * 4;
  s.pending_buf = utils.arrayCreate(s.pending_buf_size);

  s.level = level;
  s.strategy = strategy;
  s.method = method;

  return deflateReset(strm);
}

function deflateInit(strm, level) {
  return deflateInit2(strm, level, c.Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL, c.Z_DEFAULT_STRATEGY);
}

function deflateSetDictionary(/*strm, dictionary, dictLength*/) {

}

function deflateParams(/*strm, level, strategy*/) {

}

function deflateSetHeader(/*strm, head*/) {

}

function deflateBound(/*strm, sourceLen*/) {

}

function deflatePending(/*strm, pending, bits*/) {

}

function deflate(strm, flush) {
  var s = strm.state;

//  if (strm.next_out == Z_NULL ||
//    (strm.next_in == Z_NULL && strm.avail_in !== 0) ||
//    (s.status == FINISH_STATE && flush != c.Z_FINISH)) {
//    return c.Z_STREAM_ERROR;
//  }
  if (strm.avail_out === 0) {
    return c.Z_BUF_ERROR;
  }

  s.strm = strm;
  /* just in case */
  var old_flush = s.last_flush;
  /* value of flush param for previous deflate call */
  s.last_flush = flush;

  /* Write the header */
  if (s.status === INIT_STATE) {

    if (s.wrap === 2) { // GZIP header
      strm.adler = 0;  //crc32(0L, Z_NULL, 0);
      put_byte(s, 31);
      put_byte(s, 139);
      put_byte(s, 8);
      if (!s.gzhead) { // s->gzhead == Z_NULL
        put_byte(s, 0);
        put_byte(s, 0);
        put_byte(s, 0);
        put_byte(s, 0);
        put_byte(s, 0);
        put_byte(s, s.level === 9 ? 2 :
                    (s.strategy >= c.Z_HUFFMAN_ONLY || s.level < 2 ?
                     4 : 0));
        put_byte(s, OS_CODE);
        s.status = BUSY_STATE;
      }
      else {
        throw new Error('Custom GZIP headers not supported');
      }
    }
    else // DEFLATE header
    {
      var header = (c.Z_DEFLATED + ((s.w_bits - 8) << 4)) << 8;
      var level_flags = -1;

      if (s.strategy >= c.Z_HUFFMAN_ONLY || s.level < 2) {
        level_flags = 0;
      } else if (s.level < 6) {
        level_flags = 1;
      } else if (s.level === 6) {
        level_flags = 2;
      } else {
        level_flags = 3;
      }
      header |= (level_flags << 6);
      if (s.strstart !== 0) { header |= PRESET_DICT; }
      header += 31 - (header % 31);

      s.status = BUSY_STATE;
      putShortMSB(s, header);

      /* Save the adler32 of the preset dictionary: */
      if (s.strstart !== 0) {
        putShortMSB(s, strm.adler >>> 16);
        putShortMSB(s, strm.adler & 0xffff);
      }
      strm.adler = 1; // adler32(0L, Z_NULL, 0);
    }
  }

  /* Flush as much pending output as possible */
  if (s.pending !== 0) {
    flush_pending(strm);
    if (strm.avail_out === 0) {
      /* Since avail_out is 0, deflate will be called again with
       * more output space, but possibly with both pending and
       * avail_in equal to zero. There won't be anything to do,
       * but this is not an error situation so make sure we
       * return OK instead of BUF_ERROR at next call of deflate:
       */
      s.last_flush = -1;
      return c.Z_OK;
    }

    /* Make sure there is something to do and avoid duplicate consecutive
     * flushes. For repeated and useless calls with Z_FINISH, we keep
     * returning Z_STREAM_END instead of Z_BUF_ERROR.
     */
  } else if (strm.avail_in === 0 && rank(flush) <= rank(old_flush) &&
    flush !== c.Z_FINISH) {
    return c.Z_BUF_ERROR;
  }

  /* User must not provide more input after the first FINISH: */
  if (s.status === FINISH_STATE && strm.avail_in !== 0) {
    return c.Z_BUF_ERROR;
  }

  /* Start a new block or continue the current one.
   */
  if (strm.avail_in !== 0 || s.lookahead !== 0 ||
    (flush !== c.Z_NO_FLUSH && s.status !== FINISH_STATE)) {
    var bstate = s.strategy === c.Z_HUFFMAN_ONLY ? deflate_huff(s, flush) :
      (s.strategy === c.Z_RLE ? deflate_rle(s, flush) :
        configuration_table[s.level].func(s, flush));

    if (bstate === BS_FINISH_STARTED || bstate === BS_FINISH_DONE) {
      s.status = FINISH_STATE;
    }
    if (bstate === BS_NEED_MORE || bstate === BS_FINISH_STARTED) {
      if (strm.avail_out === 0) {
        s.last_flush = -1;
        /* avoid BUF_ERROR next call, see above */
      }
      return c.Z_OK;
      /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
       * of deflate should use the same flush parameter to make sure
       * that the flush is complete. So we don't have to output an
       * empty block here, this will be done at next call. This also
       * ensures that for a very small output buffer, we emit at most
       * one empty block.
       */
    }
    if (bstate === BS_BLOCK_DONE) {
      /*if (flush === c.Z_PARTIAL_FLUSH) {
        //todo:_tr_align(s);
      } else*/
      if (flush !== c.Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */
        trees._tr_stored_block(s, 0, 0, 0);
        /* For a full flush, this empty block will be recognized
         * as a special marker by inflate_sync().
         */
        if (flush === c.Z_FULL_FLUSH) {
          //CLEAR_HASH(s);             /* forget history */
// !!!! seems to be bug -> 0 in original
          s.head[s.hash_size - 1] = -1;

          if (s.lookahead === 0) {
            s.strstart = 0;
            s.block_start = 0;
            s.insert = 0;
          }
        }
      }
      flush_pending(strm);
      if (strm.avail_out === 0) {
        s.last_flush = -1;
        /* avoid BUF_ERROR at next call, see above */
        return c.Z_OK;
      }
    }
  }
  //Assert(strm->avail_out > 0, "bug2");
  //if (strm.avail_out <= 0) { throw new Error("bug2");}

  if (flush !== c.Z_FINISH) { return c.Z_OK; }
  if (s.wrap <= 0) { return c.Z_STREAM_END; }

  /* Write the trailer */
  if (s.wrap === 2) {
    put_byte(s, strm.adler & 0xff);
    put_byte(s, (strm.adler >> 8) & 0xff);
    put_byte(s, (strm.adler >> 16) & 0xff);
    put_byte(s, (strm.adler >> 24) & 0xff);
    put_byte(s, strm.total_in & 0xff);
    put_byte(s, (strm.total_in >> 8) & 0xff);
    put_byte(s, (strm.total_in >> 16) & 0xff);
    put_byte(s, (strm.total_in >> 24) & 0xff);
  }
  else
  {
    putShortMSB(s, strm.adler >>> 16);
    putShortMSB(s, strm.adler & 0xffff);
  }

  flush_pending(strm);
  /* If avail_out is zero, the application will call deflate again
   * to flush the rest.
   */
  if (s.wrap > 0) { s.wrap = -s.wrap; }
  /* write the trailer only once! */
  return s.pending !== 0 ? c.Z_OK : c.Z_STREAM_END;
}

function deflateEnd(strm) {
  var status = strm.state.status;
  if (status !== INIT_STATE &&
    status !== EXTRA_STATE &&
    status !== NAME_STATE &&
    status !== COMMENT_STATE &&
    status !== HCRC_STATE &&
    status !== BUSY_STATE &&
    status !== FINISH_STATE
  ) {
    return c.Z_STREAM_ERROR;
  }

  strm.state = Z_NULL;

  return status === BUSY_STATE ? c.Z_DATA_ERROR : c.Z_OK;
}

/* =========================================================================
 * Copy the source state to the destination state
 */
//function deflateCopy(dest, source) {
//
//}

exports.deflateInit = deflateInit;

exports.deflateInit2 = deflateInit2;

exports.deflateSetDictionary = deflateSetDictionary;

exports.deflateReset = deflateReset;

exports.deflateParams = deflateParams;

exports.deflateSetHeader = deflateSetHeader;

exports.deflateBound = deflateBound;

exports.deflatePending = deflatePending;

exports.deflate = deflate;

exports.deflateEnd = deflateEnd;