/*************************************************************************
 *
 * HTCd - Copyright (C) 1998-2006 Henrik Rydberg
 *
 * 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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#include <mime/enc.h>
#include <mime/pack.h>
#include <algorithm>

const charset special("=\"#$\\^`{|}~");
//const charset special("=!\"#$@[\\]^`{|}~");
const charset headspecial("_?");
const charset printable=cset_printable&~special;
const charset printhead=printable&~headspecial;
const mstring beg_tag("=?"),end_tag("?=");
const mstring enc_qp_tag("Q"),enc_64_tag("B");
const int WRAPAT=76;
const int HEADWRAP=WRAPAT-7;

void decodeQP(mstream& out,const sref& in)
{
  const char* p=in.begin();
  while(p<in.end()) {
    unsigned char c=*p++;
    if(c=='=') {
      if(cset_ws.test(*p)) p=in(p).past_nl().data();
      else {
        unsigned char c1=*p++,c2=*p++;
        out.put(hexasc(c1,c2));
      }
    }
    else out.put(c);
  }
}

void encodeQP(mstream& out,const sref& in)
{
  sref first,rest=in;
  while(Splitln(first,rest)) {
    int n=0;
    const char* p=first.begin();
    while(p<first.end()) {
      unsigned char c=*p++;
      if(printable.test(c)) {
        if(first(p).empty()&&cset_spaces.test(c)) { cashex(out.put('='),c); n+=3; }
        else { out.put(c); n++; }
      }
      else { cashex(out.put('='),c); n+=3; }
      if(first(p).nempty()&&n>=WRAPAT) { out.put('=')<<CRLF; n=0; }
    }
    out<<CRLF;
  }
}

static void decodeHQ(mstream& out,const sref& in)
{
  const char* p=in.begin();
  while(p<in.end()) {
    unsigned char c=*p++;
    if(c=='=') {
      unsigned char c1=*p++,c2=*p++;
      out.put(hexasc(c1,c2));
    }
    else if(c=='_') out.put(' ');
    else out.put(c);
  }
}

static int encodeHQ(mstream& out,const sref& in)
{
  int enc=0;
  const char* p=in.begin();
  while(p<in.end()) {
    unsigned char c=*p++;
    if(!printable.test(c)) enc=1;
    if(printhead.test(c)) { if(c==32) out.put('_'); else out.put(c); }
    else cashex(out.put('='),c);
  }
  return enc;
}

void decodeHeader(mstream& out,mstring& mime,const sref& in)
{
  sref e,p=in;
  while(p.nempty()) {
    p=p.adv(e=p.left_first(beg_tag));
    out<<e;
    if(p.nempty()) {
      p=p.adv(beg_tag.size());
      mime=p.left_first('?');
      p=p.adv(mime.size());
      if(p.empty()) { out<<beg_tag<<mime; p.clear(); }
      else {
        p=p.popf();
        sref enc=p.left_first('?');
        p=p.adv(enc);
        if(p.empty()) { out<<beg_tag<<mime<<"?"<<enc; p.clear(); }
        else {
          p=p.adv(e=p.popf().left_first(end_tag));
          if(p.empty()) { out<<beg_tag<<mime<<"?"<<enc<<"?"<<e; p.clear(); }
          else {
            p=p.adv(end_tag.size());
            if(eqn(enc,enc_qp_tag)) decodeHQ(out,e);
            else if(eqn(enc,enc_64_tag)) decode64(out,e);
            else out<<"BAD: ["<<mime<<"]["<<enc<<"]["<<e<<"]";
          }
        }
      }
    }
  }
}

void encodeHeader(mstream& out,const sref& mime,const sref& in)
{
  mstring tmp;
  swrite sw(tmp);
  if(encodeHQ(sw,in)) {
    int wrapat=HEADWRAP-mime.size();
    sref e,p=tmp;
    p=p.adv(e=p.left(std::min(wrapat,p.size())));
    out<<beg_tag<<mime<<"?Q?"<<e<<end_tag;
    while(p.nempty()) {
      p=p.adv(e=p.left(std::min(wrapat,p.size())));
      out<<"\r\n\t"<<beg_tag<<mime<<"?Q?"<<e<<end_tag;
    }
  }
  else {
    sref e,p=in;
    p=p.adv(e=p.left(std::min(WRAPAT,p.size())));
    out<<e;
    while(p.nempty()) {
      p=p.adv(e=p.left(std::min(WRAPAT,p.size())));
      out<<"\r\n\t"<<e;
    }
  }
}