/* Copyright (C) 1998, 2000 artofcode LLC.  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, 02111-1307.

*/

/*$Id: zfrsd.c,v 1.4.6.1.2.1 2003/01/17 00:49:06 giles Exp $ */
/* ReusableStreamDecode filter support */
#include "memory_.h"
#include "ghost.h"
#include "gxiodev.h"
#include "oper.h"
#include "stream.h"
#include "strimpl.h"
#include "sfilter.h"		/* for SubFileDecode */
#include "files.h"
#include "idict.h"
#include "idparam.h"
#include "iname.h"
#include "store.h"

/* ---------------- Reusable streams ---------------- */

/*
 * The actual work of constructing the filter is done in PostScript code.
 * The operators in this file are internal ones that handle the dirty work.
 */

/* <dict|null> .rsdparams <filters> <decodeparms|null> */
/* filters is always an array; decodeparms is always either an array */
/* of the same length as filters, or null. */
private int
zrsdparams(i_ctx_t *i_ctx_p)
{
    os_ptr op = osp;
    ref *pFilter;
    ref *pDecodeParms;
    int Intent;
    bool AsyncRead;
    ref empty_array, filter1_array, parms1_array;
    uint i;
    int code;

    make_empty_array(&empty_array, a_readonly);
    if (dict_find_string(op, "Filter", &pFilter) > 0) {
	if (!r_is_array(pFilter)) {
	    if (!r_has_type(pFilter, t_name))
		return_error(e_typecheck);
	    make_array(&filter1_array, a_readonly, 1, pFilter);
	    pFilter = &filter1_array;
	}
    } else
	pFilter = &empty_array;
    /* If Filter is undefined, ignore DecodeParms. */
    if (pFilter != &empty_array &&
	dict_find_string(op, "DecodeParms", &pDecodeParms) > 0
	) {
	if (pFilter == &filter1_array) {
	    make_array(&parms1_array, a_readonly, 1, pDecodeParms);
	    pDecodeParms = &parms1_array;
	} else if (!r_is_array(pDecodeParms))
	    return_error(e_typecheck);
	else if (r_size(pFilter) != r_size(pDecodeParms))
	    return_error(e_rangecheck);
    } else
	pDecodeParms = 0;
    for (i = 0; i < r_size(pFilter); ++i) {
	ref f, fname, dp;

	array_get(pFilter, (long)i, &f);
	if (!r_has_type(&f, t_name))
	    return_error(e_typecheck);
	name_string_ref(&f, &fname);
	if (r_size(&fname) < 6 ||
	    memcmp(fname.value.bytes + r_size(&fname) - 6, "Decode", 6)
	    )
	    return_error(e_rangecheck);
	if (pDecodeParms) {
	    array_get(pDecodeParms, (long)i, &dp);
	    if (!(r_has_type(&dp, t_dictionary) || r_has_type(&dp, t_null)))
		return_error(e_typecheck);
	}
    }
    if ((code = dict_int_param(op, "Intent", 0, 3, 0, &Intent)) < 0 ||
	(code = dict_bool_param(op, "AsyncRead", false, &AsyncRead)) < 0
	)
	return code;
    push(1);
    op[-1] = *pFilter;
    if (pDecodeParms)
	*op = *pDecodeParms;
    else
	make_null(op);
    return 0;
}

/* <file|string> <CloseSource> .reusablestream <filter> */
/*
 * The file|string operand must be a "reusable source", either:
 *      - A string or bytestring;
 *      - A readable, positionable file stream;
 *      - A readable string stream;
 *      - A SubFileDecode filter with an empty EODString and a reusable
 *      source.
 * Reusable streams are also reusable sources, but they look just like
 * ordinary file or string streams.
 */
private int make_rss(P8(i_ctx_t *i_ctx_p, os_ptr op, const byte * data,
			uint size, int space, long offset, long length,
			bool is_bytestring));
private int make_rfs(P5(i_ctx_t *i_ctx_p, os_ptr op, stream *fs,
			long offset, long length));
private int
zreusablestream(i_ctx_t *i_ctx_p)
{
    os_ptr op = osp;
    os_ptr source_op = op - 1;
    long length = max_long;
    bool close_source;
    int code;

    check_type(*op, t_boolean);
    close_source = op->value.boolval;
    if (r_has_type(source_op, t_string)) {
	uint size = r_size(source_op);

	check_read(*source_op);
	code = make_rss(i_ctx_p, source_op, source_op->value.const_bytes,
			size, r_space(source_op), 0L, size, false);
    } else if (r_has_type(source_op, t_astruct)) {
	uint size = gs_object_size(imemory, source_op->value.pstruct);

	if (gs_object_type(imemory, source_op->value.pstruct) != &st_bytes)
	    return_error(e_rangecheck);
	check_read(*source_op);
	code = make_rss(i_ctx_p, source_op,
			(const byte *)source_op->value.pstruct, size,
			r_space(source_op), 0L, size, true);
    } else {
	long offset = 0;
	stream *source;
	stream *s;

	check_read_file(source, source_op);
	s = source;
rs:
	if (s->cbuf_string.data != 0) {	/* string stream */
	    long pos = stell(s);
	    long avail = sbufavailable(s) + pos;

	    offset += pos;
	    code = make_rss(i_ctx_p, source_op, s->cbuf_string.data,
			    s->cbuf_string.size,
			    imemory_space((const gs_ref_memory_t *)s->memory),
			    offset, min(avail, length), false);
	} else if (s->file != 0) { /* file stream */
	    if (~s->modes & (s_mode_read | s_mode_seek))
		return_error(e_ioerror);
	    code = make_rfs(i_ctx_p, source_op, s, offset + stell(s), length);
	} else if (s->state->template == &s_SFD_template) {
	    /* SubFileDecode filter */
	    const stream_SFD_state *const sfd_state =
		(const stream_SFD_state *)s->state;

	    if (sfd_state->eod.size != 0)
		return_error(e_rangecheck);
	    offset += sfd_state->skip_count - sbufavailable(s);
	    if (sfd_state->count != 0) {
		long left = max(sfd_state->count, 0) + sbufavailable(s);

		if (left < length)
		    length = left;
	    }
	    s = s->strm;
	    goto rs;
	}
	else			/* some other kind of stream */
	    return_error(e_rangecheck);
	if (close_source) {
	    stream *rs = fptr(source_op);

	    rs->strm = source;	/* only for close_source */
	    rs->close_strm = true;
	}
    }
    if (code >= 0)
	pop(1);
    return code;
}

/* Make a reusable string stream. */
private int
make_rss(i_ctx_t *i_ctx_p, os_ptr op, const byte * data, uint size,
	 int string_space, long offset, long length, bool is_bytestring)
{
    stream *s;
    long left = min(length, size - offset);

    if (icurrent_space < string_space)
	return_error(e_invalidaccess);
    s = file_alloc_stream(imemory, "make_rss");
    if (s == 0)
	return_error(e_VMerror);
    sread_string_reusable(s, data + offset, max(left, 0));
    if (is_bytestring)
	s->cbuf_string.data = 0;	/* byte array, not string */
    make_stream_file(op, s, "r");
    return 0;
}

/* Make a reusable file stream. */
private int
make_rfs(i_ctx_t *i_ctx_p, os_ptr op, stream *fs, long offset, long length)
{
    gs_const_string fname;
    stream *s;
    int code;

    if (sfilename(fs, &fname) < 0)
	return_error(e_ioerror);
    if (fname.data[0] == '%')
	return_error(e_invalidfileaccess); /* can't reopen */
    /* Open the file again, to be independent of the source. */
    code = file_open_stream((const char *)fname.data, fname.size, "r",
			    fs->cbsize, &s, iodev_default->procs.fopen,
			    imemory);
    if (code < 0)
	return code;
    if (sread_subfile(s, offset, length) < 0) {
	sclose(s);
	return_error(e_ioerror);
    }
    s->close_at_eod = false;
    make_stream_file(op, s, "r");
    return 0;
}

/* ---------------- Initialization procedure ---------------- */

const op_def zfrsd_op_defs[] =
{
    {"2.reusablestream", zreusablestream},
    {"2.rsdparams", zrsdparams},
    op_def_end(0)
};