/*
 *	fhist - file history and comparison tools
 *	Copyright (C) 2000, 2002 Peter Miller;
 *	All rights reserved.
 *
 *	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., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
 *
 * MANIFEST: functions to deliver output, decoding quoted printable
 */

#include <output/private.h>
#include <output/quotprindeco.h>


typedef struct output_quoted_printable_decode_ty output_quoted_printable_decode_ty;
struct output_quoted_printable_decode_ty
{
	output_ty	inherited;
	output_ty	*deeper;
	int		delete_on_delete;
	int		state;
	int		c1;
	int		n1;
};


static void
destructor(output_ty *fp)
{
	output_quoted_printable_decode_ty *this;

	this = (output_quoted_printable_decode_ty *)fp;
	switch (this->state)
	{
	case 1:
		output_fputc(this->deeper, '=');
		break;

	case 2:
		output_fputc(this->deeper, '=');
		output_fputc(this->deeper, this->c1);
		break;
	}
	this->state = 0;
	output_flush(this->deeper);
	if (this->delete_on_delete)
	    output_delete(this->deeper);
	this->deeper = 0;
}


static const char *
filename(output_ty *fp)
{
	output_quoted_printable_decode_ty *this;

	this = (output_quoted_printable_decode_ty *)fp;
	return output_filename(this->deeper);
}


static long
otell(output_ty *fp)
{
	output_quoted_printable_decode_ty *this;

	this = (output_quoted_printable_decode_ty *)fp;
	return output_ftell(this->deeper);
}


static int
unhex(int c)
{
	switch (c)
	{
	case '0': case '1': case '2': case '3': case '4':
	case '5': case '6': case '7': case '8': case '9': 
		return (c - '0');

	case 'a': case 'b': case 'c': case 'd': case 'e': case 'f': 
		return (c - 'a' + 10);

	case 'A': case 'B': case 'C': case 'D': case 'E': case 'F': 
		return (c - 'A' + 10);
	}
	return -1;
}


static void
oputc(output_ty *fp, int c)
{
	output_quoted_printable_decode_ty *this;
	int		n;

	this = (output_quoted_printable_decode_ty *)fp;
	switch (this->state)
	{
	case 0:
		state0:
		if (c == '=')
		{
			this->state = 1;
			break;
		}
		output_fputc(this->deeper, c);
		break;

	case 1:
		if (c == '\n')
		{
			this->state = 0;
			break;
		}
		n = unhex(c);
		if (n >= 0)
		{
			this->n1 = n;
			this->c1 = c;
			this->state = 2;
			break;
		}
		output_fputc(this->deeper, '=');
		this->state = 0;
		goto state0;

	case 2:
		this->state = 0;
		n = unhex(c);
		if (n >= 0)
		{
			output_fputc(this->deeper, (this->n1 << 4) + n);
			break;
		}
		output_fputc(this->deeper, '=');
		output_fputc(this->deeper, this->c1);
		goto state0;
	}
}


static void
oflush(output_ty *fp)
{
	output_quoted_printable_decode_ty *this;

	this = (output_quoted_printable_decode_ty *)fp;
	output_flush(this->deeper);
}


static output_vtbl_ty vtbl =
{
	sizeof(output_quoted_printable_decode_ty),
	destructor,
	filename,
	otell,
	oputc,
	output_generic_fputs,
	output_generic_write,
	oflush,
	"quoted_printable_decode",
};


output_ty *
output_quoted_printable_decode(output_ty *deeper, int dod)
{
	output_ty	*result;
	output_quoted_printable_decode_ty *this;

	result = output_new(&vtbl);
	this = (output_quoted_printable_decode_ty *)result;
	this->deeper = deeper;
	this->delete_on_delete = dod;
	this->state = 0;
	return result;
}