/* 
   Copyright (C) Andrew Tridgell 1996
   Copyright (C) Paul Mackerras 1996
   
   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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include "rsync.h"

extern int csum_length;

extern int verbose;
extern int am_server;

extern int remote_version;

typedef unsigned short tag;

#define TABLESIZE (1<<16)
#define NULL_TAG ((tag)-1)

static int false_alarms;
static int tag_hits;
static int matches;
static int data_transfer;

static int total_false_alarms;
static int total_tag_hits;
static int total_matches;
static int64 total_data_transfer;


struct target {
  tag t;
  int i;
};

static struct target *targets;

static tag *tag_table;

#define gettag2(s1,s2) (((s1) + (s2)) & 0xFFFF)
#define gettag(sum) gettag2((sum)&0xFFFF,(sum)>>16)

static int compare_targets(struct target *t1,struct target *t2)
{
  return((int)t1->t - (int)t2->t);
}


static void build_hash_table(struct sum_struct *s)
{
  int i;

  if (!tag_table)
    tag_table = (tag *)malloc(sizeof(tag)*TABLESIZE);

  targets = (struct target *)malloc(sizeof(targets[0])*s->count);
  if (!tag_table || !targets) 
    out_of_memory("build_hash_table");

  for (i=0;i<s->count;i++) {
    targets[i].i = i;
    targets[i].t = gettag(s->sums[i].sum1);
  }

  qsort(targets,s->count,sizeof(targets[0]),(int (*)())compare_targets);

  for (i=0;i<TABLESIZE;i++)
    tag_table[i] = NULL_TAG;

  for (i=s->count-1;i>=0;i--) {    
    tag_table[targets[i].t] = i;
  }
}


static OFF_T last_match;


static void matched(int f,struct sum_struct *s,struct map_struct *buf,
		    OFF_T offset,int i)
{
	OFF_T n = offset - last_match;
	int j;

	if (verbose > 2 && i >= 0)
		rprintf(FINFO,"match at %d last_match=%d j=%d len=%d n=%d\n",
			(int)offset,(int)last_match,i,(int)s->sums[i].len,(int)n);

	send_token(f,i,buf,last_match,n,i<0?0:s->sums[i].len);
	data_transfer += n;

	if (n > 0)
		write_flush(f);

	if (i >= 0)
		n += s->sums[i].len;
  
	for (j=0;j<n;j+=CHUNK_SIZE) {
		int n1 = MIN(CHUNK_SIZE,n-j);
		sum_update(map_ptr(buf,last_match+j,n1),n1);
	}


	if (i >= 0)
		last_match = offset + s->sums[i].len;
	else
		last_match = offset;
}


static void hash_search(int f,struct sum_struct *s,
			struct map_struct *buf,OFF_T len)
{
	OFF_T offset;
	int j,k;
	int end;
	char sum2[SUM_LENGTH];
	uint32 s1, s2, sum; 
	schar *map;
	extern int do_compression;

	if (verbose > 2)
		rprintf(FINFO,"hash search b=%d len=%d\n",s->n,(int)len);

	k = MIN(len, s->n);
	
	map = (schar *)map_ptr(buf,0,k);
	
	sum = get_checksum1((char *)map, k);
	s1 = sum & 0xFFFF;
	s2 = sum >> 16;
	if (verbose > 3)
		rprintf(FINFO, "sum=%.8x k=%d\n", sum, k);
	
	offset = 0;
	
	end = len + 1 - s->sums[s->count-1].len;
	
	if (verbose > 3)
		rprintf(FINFO,"hash search s->n=%d len=%d count=%d\n",
			s->n,(int)len,s->count);
	
	do {
		tag t = gettag2(s1,s2);
		int done_csum2 = 0;
			
		j = tag_table[t];
		if (verbose > 4)
			rprintf(FINFO,"offset=%d sum=%08x\n",(int)offset,sum);
		
		if (j == NULL_TAG) {
			goto null_tag;
		}

		sum = (s1 & 0xffff) | (s2 << 16);
		tag_hits++;
		for (; j<s->count && targets[j].t == t; j++) {
			int i = targets[j].i;
			
			if (sum != s->sums[i].sum1) continue;
			
			if (verbose > 3)
				rprintf(FINFO,"potential match at %d target=%d %d sum=%08x\n",
					(int)offset,j,i,sum);
			
			if (!done_csum2) {
				int l = MIN(s->n,len-offset);
				map = (schar *)map_ptr(buf,offset,l);
				get_checksum2((char *)map,l,sum2);
				done_csum2 = 1;
			}
			
			if (memcmp(sum2,s->sums[i].sum2,csum_length) != 0) {
				false_alarms++;
				continue;
			}
			
			matched(f,s,buf,offset,i);
			offset += s->sums[i].len - 1;
			k = MIN((len-offset), s->n);
			map = (schar *)map_ptr(buf,offset,k);
			sum = get_checksum1((char *)map, k);
			s1 = sum & 0xFFFF;
			s2 = sum >> 16;
			matches++;
			break;
		}
		
	null_tag:
		/* Trim off the first byte from the checksum */
		map = (schar *)map_ptr(buf,offset,k+1);
		s1 -= map[0] + CHAR_OFFSET;
		s2 -= k * (map[0]+CHAR_OFFSET);
		
		/* Add on the next byte (if there is one) to the checksum */
		if (k < (len-offset)) {
			s1 += (map[k]+CHAR_OFFSET);
			s2 += s1;
		} else {
			--k;
		}

		if (!do_compression) {
			/* By matching early we avoid re-reading the
			   data 3 times in the case where a token
			   match comes a long way after last
			   match. The 3 reads are caused by the
			   running match, the checksum update and the
			   literal send.

			   we don't enable this for the compressed
			   case yet as the deflated token code can't
			   handle it. Paul is working on it */
			if (offset-last_match >= CHUNK_SIZE+s->n && 
			    (end-offset > CHUNK_SIZE)) {
				matched(f,s,buf,offset - s->n, -2);
			}
		}
	} while (++offset < end);
	
	matched(f,s,buf,len,-1);
	map_ptr(buf,len-1,1);
}


void match_sums(int f,struct sum_struct *s,struct map_struct *buf,OFF_T len)
{
	char file_sum[MD4_SUM_LENGTH];

	last_match = 0;
	false_alarms = 0;
	tag_hits = 0;
	matches=0;
	data_transfer=0;

	sum_init();

	if (len > 0 && s->count>0) {
		build_hash_table(s);
		
		if (verbose > 2) 
			rprintf(FINFO,"built hash table\n");
		
		hash_search(f,s,buf,len);
		
		if (verbose > 2) 
			rprintf(FINFO,"done hash search\n");
	} else {
		matched(f,s,buf,len,-1);
	}

	sum_end(file_sum);

	if (remote_version >= 14) {
		if (verbose > 2)
			rprintf(FINFO,"sending file_sum\n");
		write_buf(f,file_sum,MD4_SUM_LENGTH);
	}

	if (targets) {
		free(targets);
		targets=NULL;
	}
	
	if (verbose > 2)
		rprintf(FINFO, "false_alarms=%d tag_hits=%d matches=%d\n",
			false_alarms, tag_hits, matches);
	
	total_tag_hits += tag_hits;
	total_false_alarms += false_alarms;
	total_matches += matches;
	total_data_transfer += data_transfer;
}

void match_report(void)
{
	if (verbose <= 1)
		return;

	rprintf(FINFO,
		"total: matches=%d  tag_hits=%d  false_alarms=%d  data=%ld\n",
		total_matches,total_tag_hits,
		total_false_alarms,(long)total_data_transfer);
}