/*  Tarlz - Archiver with multimember lzip compression
    Copyright (C) 2013-2019 Antonio Diaz Diaz.

    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, see <http://www.gnu.org/licenses/>.
*/

#define _FILE_OFFSET_BITS 64

#include <algorithm>
#include <cerrno>
#include <climits>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <queue>
#include <string>
#include <vector>
#include <pthread.h>
#include <stdint.h>
#include <unistd.h>
#include <sys/stat.h>
#include <ftw.h>
#include <lzlib.h>

#include "arg_parser.h"
#include "tarlz.h"


namespace {

enum { max_packet_size = 1 << 20 };
class Packet_courier;
Packet_courier * courierp = 0;		// local vars needed by add_member
unsigned long long partial_data_size = 0;	// size of current block


class Slot_tally
  {
  const int num_slots;				// total slots
  int num_free;					// remaining free slots
  pthread_mutex_t mutex;
  pthread_cond_t slot_av;			// slot available

  Slot_tally( const Slot_tally & );		// declared as private
  void operator=( const Slot_tally & );		// declared as private

public:
  explicit Slot_tally( const int slots )
    : num_slots( slots ), num_free( slots )
    { xinit_mutex( &mutex ); xinit_cond( &slot_av ); }

  ~Slot_tally() { xdestroy_cond( &slot_av ); xdestroy_mutex( &mutex ); }

  bool all_free() { return ( num_free == num_slots ); }

  void get_slot()				// wait for a free slot
    {
    xlock( &mutex );
    while( num_free <= 0 ) xwait( &slot_av, &mutex );
    --num_free;
    xunlock( &mutex );
    }

  void leave_slot()				// return a slot to the tally
    {
    xlock( &mutex );
    if( ++num_free == 1 ) xsignal( &slot_av );	// num_free was 0
    xunlock( &mutex );
    }
  };


struct Ipacket			// filename, file size and headers
  {
  const unsigned long long file_size;
  const std::string filename;	// filename.empty() means end of lzip member
  const Extended * const extended;
  const uint8_t * const header;

  Ipacket() : file_size( 0 ), extended( 0 ), header( 0 ) {}
  Ipacket( const char * const name, const unsigned long long s,
           const Extended * const ext, const uint8_t * const head )
    : file_size( s ), filename( name ), extended( ext ), header( head ) {}
  };

struct Opacket		// compressed data to be written to the archive
  {
  const uint8_t * const data;	// data == 0 means end of lzip member
  const int size;		// number of bytes in data (if any)

  Opacket() : data( 0 ), size( 0 ) {}
  Opacket( uint8_t * const d, const int s ) : data( d ), size( s ) {}
  };


class Packet_courier			// moves packets around
  {
public:
  unsigned icheck_counter;
  unsigned iwait_counter;
  unsigned ocheck_counter;
  unsigned owait_counter;
private:
  int receive_worker_id;	// worker queue currently receiving packets
  int deliver_worker_id;	// worker queue currently delivering packets
  Slot_tally slot_tally;		// limits the number of input packets
  std::vector< std::queue< const Ipacket * > > ipacket_queues;
  std::vector< std::queue< const Opacket * > > opacket_queues;
  int num_working;			// number of workers still running
  const int num_workers;		// number of workers
  const unsigned out_slots;		// max output packets per queue
  pthread_mutex_t imutex;
  pthread_cond_t iav_or_eof;	// input packet available or grouper done
  pthread_mutex_t omutex;
  pthread_cond_t oav_or_exit;	// output packet available or all workers exited
  std::vector< pthread_cond_t > slot_av;	// output slot available
  bool eof;					// grouper done

  Packet_courier( const Packet_courier & );	// declared as private
  void operator=( const Packet_courier & );	// declared as private

public:
  Packet_courier( const int workers, const int in_slots, const int oslots )
    : icheck_counter( 0 ), iwait_counter( 0 ),
      ocheck_counter( 0 ), owait_counter( 0 ),
      receive_worker_id( 0 ), deliver_worker_id( 0 ),
      slot_tally( in_slots ), ipacket_queues( workers ),
      opacket_queues( workers ), num_working( workers ),
      num_workers( workers ), out_slots( oslots ), slot_av( workers ),
      eof( false )
    {
    xinit_mutex( &imutex ); xinit_cond( &iav_or_eof );
    xinit_mutex( &omutex ); xinit_cond( &oav_or_exit );
    for( unsigned i = 0; i < slot_av.size(); ++i ) xinit_cond( &slot_av[i] );
    }

  ~Packet_courier()
    {
    for( unsigned i = 0; i < slot_av.size(); ++i ) xdestroy_cond( &slot_av[i] );
    xdestroy_cond( &oav_or_exit ); xdestroy_mutex( &omutex );
    xdestroy_cond( &iav_or_eof ); xdestroy_mutex( &imutex );
    }

  /* Receive an ipacket from grouper.
     If filename.empty() (end of lzip member token), move to next queue. */
  void receive_packet( const Ipacket * const ipacket )
    {
    if( ipacket->filename.size() )
      slot_tally.get_slot();		// wait for a free slot
    xlock( &imutex );
    ipacket_queues[receive_worker_id].push( ipacket );
    if( ipacket->filename.empty() && ++receive_worker_id >= num_workers )
      receive_worker_id = 0;
    xbroadcast( &iav_or_eof );
    xunlock( &imutex );
    }

  // distribute an ipacket to a worker
  const Ipacket * distribute_packet( const int worker_id )
    {
    const Ipacket * ipacket = 0;
    xlock( &imutex );
    ++icheck_counter;
    while( ipacket_queues[worker_id].empty() && !eof )
      {
      ++iwait_counter;
      xwait( &iav_or_eof, &imutex );
      }
    if( !ipacket_queues[worker_id].empty() )
      {
      ipacket = ipacket_queues[worker_id].front();
      ipacket_queues[worker_id].pop();
      }
    xunlock( &imutex );
    if( ipacket )
      { if( ipacket->filename.size() ) slot_tally.leave_slot(); }
    else
      {
      // notify muxer when last worker exits
      xlock( &omutex );
      if( --num_working == 0 ) xsignal( &oav_or_exit );
      xunlock( &omutex );
      }
    return ipacket;
    }

  // collect an opacket from a worker
  void collect_packet( const Opacket * const opacket, const int worker_id )
    {
    xlock( &omutex );
    if( opacket->data )
      {
      while( opacket_queues[worker_id].size() >= out_slots )
        xwait( &slot_av[worker_id], &omutex );
      }
    opacket_queues[worker_id].push( opacket );
    if( worker_id == deliver_worker_id ) xsignal( &oav_or_exit );
    xunlock( &omutex );
    }

  /* Deliver an opacket to muxer.
     If opacket data == 0, move to next queue and wait again. */
  const Opacket * deliver_packet()
    {
    const Opacket * opacket = 0;
    xlock( &omutex );
    ++ocheck_counter;
    while( true )
      {
      while( opacket_queues[deliver_worker_id].empty() && num_working > 0 )
        {
        ++owait_counter;
        xwait( &oav_or_exit, &omutex );
        }
      if( opacket_queues[deliver_worker_id].empty() ) break;
      opacket = opacket_queues[deliver_worker_id].front();
      opacket_queues[deliver_worker_id].pop();
      if( opacket_queues[deliver_worker_id].size() + 1 == out_slots )
        xsignal( &slot_av[deliver_worker_id] );
      if( opacket->data ) break;
      if( ++deliver_worker_id >= num_workers ) deliver_worker_id = 0;
      delete opacket; opacket = 0;
      }
    xunlock( &omutex );
    return opacket;
    }

  void finish()			// grouper has no more packets to send
    {
    xlock( &imutex );
    eof = true;
    xbroadcast( &iav_or_eof );
    xunlock( &imutex );
    }

  bool finished()		// all packets delivered to muxer
    {
    if( !slot_tally.all_free() || !eof || num_working != 0 ) return false;
    for( int i = 0; i < num_workers; ++i )
      if( !ipacket_queues[i].empty() ) return false;
    for( int i = 0; i < num_workers; ++i )
      if( !opacket_queues[i].empty() ) return false;
    return true;
    }
  };


// send one ipacket with tar member metadata to courier
int add_member( const char * const filename, const struct stat *,
                const int flag, struct FTW * )
  {
  unsigned long long file_size = 0;
  // metadata for extended records
  Extended * const extended = new( std::nothrow ) Extended;
  uint8_t * const header = extended ? new( std::nothrow ) Tar_header : 0;
  if( !header )
    { show_error( mem_msg ); if( extended ) delete extended; return 1; }
  if( !fill_headers( filename, *extended, header, file_size, flag ) )
    { delete[] header; delete extended; return 0; }

  if( solidity == bsolid &&
      block_is_full( *extended, file_size, partial_data_size ) )
    courierp->receive_packet( new Ipacket );		// end of group

  courierp->receive_packet( new Ipacket( filename, file_size, extended, header ) );

  if( solidity == no_solid )			// one tar member per group
    courierp->receive_packet( new Ipacket );
  if( verbosity >= 1 ) std::fprintf( stderr, "%s\n", filename );
  return 0;
  }


struct Grouper_arg
  {
  Packet_courier * courier;
  const Arg_parser * parser;
  };


/* Package metadata of the files to be archived and pass them to the
   courier for distribution to workers. */
extern "C" void * grouper( void * arg )
  {
  const Grouper_arg & tmp = *(const Grouper_arg *)arg;
  Packet_courier & courier = *tmp.courier;
  const Arg_parser & parser = *tmp.parser;

  for( int i = 0; i < parser.arguments(); ++i )		// parse command line
    {
    const int code = parser.code( i );
    const std::string & arg = parser.argument( i );
    const char * filename = arg.c_str();
    if( code == 'C' && chdir( filename ) != 0 )
      { show_file_error( filename, "Error changing working directory", errno );
        cleanup_and_fail(); }
    if( code ) continue;				// skip options
    if( parser.argument( i ).empty() ) continue;	// skip empty names
    std::string deslashed;		// arg without trailing slashes
    unsigned len = arg.size();
    while( len > 1 && arg[len-1] == '/' ) --len;
    if( len < arg.size() )
      { deslashed.assign( arg, 0, len ); filename = deslashed.c_str(); }
    struct stat st;
    if( lstat( filename, &st ) != 0 )	// filename from command line
      { show_file_error( filename, "Can't stat input file", errno );
        set_error_status( 1 ); }
    else if( nftw( filename, add_member, 16, FTW_PHYS ) != 0 )
      cleanup_and_fail();			// write error or oom
    else if( solidity == dsolid )		// end of group
      courier.receive_packet( new Ipacket );
    }

  if( solidity == bsolid && partial_data_size )		// finish last block
    { partial_data_size = 0; courierp->receive_packet( new Ipacket ); }
  courier.finish();			// no more packets to send
  return 0;
  }


/* Writes ibuf to encoder. To minimize dictionary size, it does not read
   from encoder until encoder's input buffer is full or finish is true.
   Sends opacket to courier and allocates new obuf each time obuf is full. */
void loop_encode( const uint8_t * const ibuf, const int isize,
                  uint8_t * & obuf, int & opos, Packet_courier & courier,
                  LZ_Encoder * const encoder, const int worker_id,
                  const bool finish = false )
  {
  int ipos = 0;
  if( opos < 0 || opos > max_packet_size )
    internal_error( "bad buffer index in loop_encode." );
  while( true )
    {
    if( ipos < isize )
      {
      const int wr = LZ_compress_write( encoder, ibuf + ipos, isize - ipos );
      if( wr < 0 ) internal_error( "library error (LZ_compress_write)." );
      ipos += wr;
      }
    if( ipos >= isize )					// ibuf is empty
      { if( finish ) LZ_compress_finish( encoder ); else break; }
    const int rd =
      LZ_compress_read( encoder, obuf + opos, max_packet_size - opos );
    if( rd < 0 )
      {
      if( verbosity >= 0 )
        std::fprintf( stderr, "LZ_compress_read error: %s\n",
                      LZ_strerror( LZ_compress_errno( encoder ) ) );
      cleanup_and_fail();
      }
    opos += rd;
    // obuf is full or last opacket in lzip member
    if( opos >= max_packet_size || LZ_compress_finished( encoder ) == 1 )
      {
      if( opos > max_packet_size )
        internal_error( "opacket size exceeded in worker." );
      courier.collect_packet( new Opacket( obuf, opos ), worker_id );
      opos = 0; obuf = new( std::nothrow ) uint8_t[max_packet_size];
      if( !obuf ) { show_error( mem_msg2 ); cleanup_and_fail(); }
      if( LZ_compress_finished( encoder ) == 1 )
        {
        if( LZ_compress_restart_member( encoder, LLONG_MAX ) >= 0 ) break;
        show_error( "LZ_compress_restart_member failed." ); cleanup_and_fail();
        }
      }
    }
  if( ipos > isize ) internal_error( "ipacket size exceeded in worker." );
  if( ipos < isize ) internal_error( "input not fully consumed in worker." );
  }


struct Worker_arg
  {
  Packet_courier * courier;
  int dictionary_size;
  int match_len_limit;
  int worker_id;
  };


/* Get ipackets from courier, compress headers and file data, and give the
   opackets produced to courier. */
extern "C" void * cworker( void * arg )
  {
  const Worker_arg & tmp = *(const Worker_arg *)arg;
  Packet_courier & courier = *tmp.courier;
  const int dictionary_size = tmp.dictionary_size;
  const int match_len_limit = tmp.match_len_limit;
  const int worker_id = tmp.worker_id;

  LZ_Encoder * encoder = 0;
  uint8_t * data = 0;
  Resizable_buffer rbuf( 2 * header_size );	// extended header + data
  if( !rbuf.size() ) { show_error( mem_msg2 ); cleanup_and_fail(); }

  int opos = 0;
  bool flushed = true;		// avoid producing empty lzip members
  while( true )
    {
    const Ipacket * const ipacket = courier.distribute_packet( worker_id );
    if( !ipacket ) break;		// no more packets to process
    if( ipacket->filename.empty() )	// end of group
      {
      if( !flushed )			// this lzip member is not empty
        loop_encode( 0, 0, data, opos, courier, encoder, worker_id, true );
      courier.collect_packet( new Opacket, worker_id );	// end of member token
      flushed = true; delete ipacket; continue;
      }

    const int infd =
      ipacket->file_size ? open_instream( ipacket->filename.c_str() ) : -1;
    if( ipacket->file_size && infd < 0 )	// can't read file data
      { delete[] ipacket->header; delete ipacket->extended; delete ipacket;
        set_error_status( 1 ); continue; }	// skip file

    flushed = false;
    if( !encoder )		// init encoder just before using it
      {
      data = new( std::nothrow ) uint8_t[max_packet_size];
      encoder = LZ_compress_open( dictionary_size, match_len_limit, LLONG_MAX );
      if( !data || !encoder || LZ_compress_errno( encoder ) != LZ_ok )
        {
        if( !data || !encoder || LZ_compress_errno( encoder ) == LZ_mem_error )
          show_error( mem_msg2 );
        else
          internal_error( "invalid argument to encoder." );
        cleanup_and_fail();
        }
      }

    if( !ipacket->extended->empty() )		// compress extended block
      {
      const long long ebsize = ipacket->extended->format_block( rbuf );
      if( ebsize < 0 )
        { show_error( "Error formatting extended records." ); cleanup_and_fail(); }
      /* Limit the size of the extended block to INT_MAX - 1 so that it can
         be fed to lzlib as one buffer. */
      if( ebsize >= INT_MAX )
        { show_error( "Extended records size >= INT_MAX." ); cleanup_and_fail(); }
      loop_encode( (const uint8_t *)rbuf(), ebsize, data, opos, courier,
                   encoder, worker_id );
      }
    // compress ustar header
    loop_encode( ipacket->header, header_size, data, opos, courier,
                 encoder, worker_id );
    delete[] ipacket->header; delete ipacket->extended;

    if( ipacket->file_size )
      {
      enum { bufsize = 32 * header_size };
      uint8_t buf[bufsize];
      unsigned long long rest = ipacket->file_size;
      while( rest > 0 )
        {
        int size = std::min( rest, (unsigned long long)bufsize );
        const int rd = readblock( infd, buf, size );
        rest -= rd;
        if( rd != size )
          {
          if( verbosity >= 0 )
            std::fprintf( stderr, "File '%s' ends unexpectedly at pos %llu\n",
                          ipacket->filename.c_str(), ipacket->file_size - rest );
          close( infd ); cleanup_and_fail();
          }
        if( rest == 0 )				// last read
          {
          const int rem = ipacket->file_size % header_size;
          if( rem > 0 )
            { const int padding = header_size - rem;
              std::memset( buf + size, 0, padding ); size += padding; }
          }
        // compress size bytes of file
        loop_encode( buf, size, data, opos, courier, encoder, worker_id );
        }
      if( close( infd ) != 0 )
        { show_file_error( ipacket->filename.c_str(), "Error closing file", errno );
          cleanup_and_fail(); }
      }
    delete ipacket;
    }
  if( data ) delete[] data;
  if( encoder && LZ_compress_close( encoder ) < 0 )
    { show_error( "LZ_compress_close failed." ); cleanup_and_fail(); }
  return 0;
  }


/* Get from courier the processed and sorted packets, and write
   their contents to the output archive. */
void muxer( Packet_courier & courier, const int outfd )
  {
  while( true )
    {
    const Opacket * const opacket = courier.deliver_packet();
    if( !opacket ) break;	// queue is empty. all workers exited

    if( !writeblock_wrapper( outfd, opacket->data, opacket->size ) )
      cleanup_and_fail();
    delete[] opacket->data;
    delete opacket;
    }
  }

} // end namespace


// init the courier, then start the grouper and the workers and call the muxer
int encode_lz( const Arg_parser & parser, const int dictionary_size,
               const int match_len_limit, const int num_workers,
               const int outfd, const int debug_level )
  {
  const int in_slots = 65536;		// max small files (<=512B) in 64 MiB
  const int total_in_slots = ( INT_MAX / num_workers >= in_slots ) ?
                             num_workers * in_slots : INT_MAX;
  const int out_slots = 64;

  /* If an error happens after any threads have been started, exit must be
     called before courier goes out of scope. */
  Packet_courier courier( num_workers, total_in_slots, out_slots );
  courierp = &courier;			// needed by add_member

  Grouper_arg grouper_arg;
  grouper_arg.courier = &courier;
  grouper_arg.parser = &parser;

  pthread_t grouper_thread;
  int errcode = pthread_create( &grouper_thread, 0, grouper, &grouper_arg );
  if( errcode )
    { show_error( "Can't create grouper thread", errcode ); cleanup_and_fail(); }

  Worker_arg * worker_args = new( std::nothrow ) Worker_arg[num_workers];
  pthread_t * worker_threads = new( std::nothrow ) pthread_t[num_workers];
  if( !worker_args || !worker_threads )
    { show_error( mem_msg ); cleanup_and_fail(); }
  for( int i = 0; i < num_workers; ++i )
    {
    worker_args[i].courier = &courier;
    worker_args[i].dictionary_size = dictionary_size;
    worker_args[i].match_len_limit = match_len_limit;
    worker_args[i].worker_id = i;
    errcode = pthread_create( &worker_threads[i], 0, cworker, &worker_args[i] );
    if( errcode )
      { show_error( "Can't create worker threads", errcode ); cleanup_and_fail(); }
    }

  muxer( courier, outfd );

  for( int i = num_workers - 1; i >= 0; --i )
    {
    errcode = pthread_join( worker_threads[i], 0 );
    if( errcode )
      { show_error( "Can't join worker threads", errcode ); cleanup_and_fail(); }
    }
  delete[] worker_threads;
  delete[] worker_args;

  errcode = pthread_join( grouper_thread, 0 );
  if( errcode )
    { show_error( "Can't join grouper thread", errcode ); cleanup_and_fail(); }

  // write End-Of-Archive records
  int retval = 0;
  enum { eof_member_size = 44 };
  const uint8_t eof_member[eof_member_size] = {
    0x4C, 0x5A, 0x49, 0x50, 0x01, 0x0C, 0x00, 0x00, 0x6F, 0xFD, 0xFF, 0xFF,
    0xA3, 0xB7, 0x80, 0x0C, 0x82, 0xDB, 0xFF, 0xFF, 0x9F, 0xF0, 0x00, 0x00,
    0x2E, 0xAF, 0xB5, 0xEF, 0x00, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x2C, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
  if( !writeblock_wrapper( outfd, eof_member, eof_member_size ) ) retval = 1;

  if( close( outfd ) != 0 && !retval )
    { show_error( "Error closing archive", errno ); retval = 1; }

  if( debug_level & 1 )
    std::fprintf( stderr,
      "any worker tried to consume from grouper %8u times\n"
      "any worker had to wait                   %8u times\n"
      "muxer tried to consume from workers      %8u times\n"
      "muxer had to wait                        %8u times\n",
      courier.icheck_counter,
      courier.iwait_counter,
      courier.ocheck_counter,
      courier.owait_counter );

  if( !courier.finished() ) internal_error( "courier not finished." );
  return final_exit_status( retval );
  }