#include "hash.h"

/*

 * I originally attemped to just convert surf.c to pure Ruby, but I

 * confess a lack of understanding surrounding the char casts from

 * unsigned ints, etc, and screwing up a hash algo doesn't do anyone

 * any good, least of all, me.  In other words, I don't have to fully

 * understand DJB code to trust in it. :-)

 *

 * The following is copied verbatim from the ezmlm-idx source, version

 * 7.2.2.  See: subhash.c, surf.c, and surfpcs.c.

 *

*/

static

void surf(unsigned int out[8],const unsigned int in[12],const unsigned int seed[32])

{

  unsigned int t[12]; unsigned int x; unsigned int sum = 0;

  int r; int i; int loop;

  for (i = 0;i < 12;++i) t[i] = in[i] ^ seed[12 + i];

  for (i = 0;i < 8;++i) out[i] = seed[24 + i];

  x = t[11];

  for (loop = 0;loop < 2;++loop) {

    for (r = 0;r < 16;++r) {

      sum += 0x9e3779b9;

      MUSH(0,5) MUSH(1,7) MUSH(2,9) MUSH(3,13)

      MUSH(4,5) MUSH(5,7) MUSH(6,9) MUSH(7,13)

      MUSH(8,5) MUSH(9,7) MUSH(10,9) MUSH(11,13)

    }

    for (i = 0;i < 8;++i) out[i] ^= t[i + 4];

  }

}

static

void surfpcs_init(surfpcs *s,const unsigned int k[32])

{

  int i;

  for (i = 0;i < 32;++i) s->seed[i] = k[i];

  for (i = 0;i < 8;++i) s->sum[i] = 0;

  for (i = 0;i < 12;++i) s->in[i] = 0;

  s->todo = 0;

}

static

void surfpcs_add(surfpcs *s,const char *x,unsigned int n)

{

  int i;

  while (n--) {

    data[end[s->todo++]] = *x++;

    if (s->todo == 32) {

      s->todo = 0;

      if (!++s->in[8])

        if (!++s->in[9])

          if (!++s->in[10])

            ++s->in[11];

      surf(s->out,s->in,s->seed);

      for (i = 0;i < 8;++i)

	s->sum[i] += s->out[i];

    }

  }

}

static

void surfpcs_addlc(surfpcs *s,const char *x,unsigned int n)

/* modified from surfpcs_add by case-independence and skipping ' ' & '\t' */

{

  unsigned char ch;

  int i;

  while (n--) {

    ch = *x++;

    if (ch == ' ' || ch == '\t') continue;

    if (ch >= 'A' && ch <= 'Z')

      ch -= 'a' - 'A';

    data[end[s->todo++]] = ch;

    if (s->todo == 32) {

      s->todo = 0;

      if (!++s->in[8])

        if (!++s->in[9])

          if (!++s->in[10])

            ++s->in[11];

      surf(s->out,s->in,s->seed);

      for (i = 0;i < 8;++i)

	  s->sum[i] += s->out[i];

    }

  }

}

static

void surfpcs_out(surfpcs *s,unsigned char h[32])

{

  int i;

  surfpcs_add(s,".",1);

  while (s->todo) surfpcs_add(s,"",1);

  for (i = 0;i < 8;++i) s->in[i] = s->sum[i];

  for (;i < 12;++i) s->in[i] = 0;

  surf(s->out,s->in,s->seed);

  for (i = 0;i < 32;++i) h[i] = outdata[end[i]];

}

static

void makehash(const char *indata,unsigned int inlen,char *hash)

	/* makes hash[COOKIE=20] from stralloc *indata, ignoring case and */

	/* SPACE/TAB */

{

  unsigned char h[32];

  surfpcs s;

  unsigned int seed[32];

  int i;

  for (i = 0;i < 32;++i) seed[i] = 0;

  surfpcs_init(&s,seed);

  surfpcs_addlc(&s,indata,inlen);

  surfpcs_out(&s,h);

  for (i = 0;i < 20;++i)

    hash[i] = 'a' + (h[i] & 15);

}

static

unsigned int subhashb(const char *s,long len)

{

  unsigned long h;

  h = 5381;

  while (len-- > 0)

    h = (h + (h << 5)) ^ (unsigned int)*s++;

  return h % 53;

}

static

unsigned int subhashs(const char *s)

{

  return subhashb(s,strlen(s));

}

/* end copy of ezmlm-idx source */

/*

 * call-seq:

 *   Ezmlm::Hash.address( email ) -> String

 *

 * Call the Surf hashing function on an +email+ address, returning

 * the hashed string.  This is specific to how ezmlm is seeding

 * the hash, and parsing email addresses from messages (prefixed with

 * the '<' character.)

 *

 */

static VALUE

address( VALUE klass, VALUE email ) {

	char hash[20];

	char *input;

	Check_Type( email, T_STRING );

	email = rb_str_plus( rb_str_new2("<"), email );

	input = StringValueCStr( email );

	makehash( input, strlen(input), hash );

	return rb_str_new( hash, 20 );

}

/*

 * call-seq:

 *   Ezmlm::Hash.subscriber( address ) -> String

 *

 * Call the subscriber hashing function on an email +address+, returning

 * the index character referring to the file containing subscriber presence.

 *

 */

static VALUE

subscriber( VALUE klass, VALUE email ) {

	unsigned int prefix;

	Check_Type( email, T_STRING );

	email  = rb_str_plus( rb_str_new2("T"), email);

	prefix = subhashs( StringValueCStr(email) ) + 64;

	return rb_sprintf( "%c", (char)prefix );

}

void

Init_hash()

{

	rb_mEzmlm  = rb_define_module( "Ezmlm" );

	rb_cEZHash = rb_define_class_under( rb_mEzmlm, "Hash", rb_cObject );

	rb_define_module_function( rb_cEZHash, "address", address, 1 );

	rb_define_module_function( rb_cEZHash, "subscriber", subscriber, 1 );

	return;

}