/* Copyright (C) 1998, 1999 Aladdin Enterprises.  All rights reserved.

   This file is part of Aladdin Ghostscript.

   Aladdin Ghostscript is distributed with NO WARRANTY OF ANY KIND.  No author
   or distributor accepts any responsibility for the consequences of using it,
   or for whether it serves any particular purpose or works at all, unless he
   or she says so in writing.  Refer to the Aladdin Ghostscript Free Public
   License (the "License") for full details.

   Every copy of Aladdin Ghostscript must include a copy of the License,
   normally in a plain ASCII text file named PUBLIC.  The License grants you
   the right to copy, modify and redistribute Aladdin Ghostscript, but only
   under certain conditions described in the License.  Among other things, the
   License requires that the copyright notice and this notice be preserved on
   all copies.
 */

/*$Id: zfreuse.c $ */
/* ReusableStreamDecode filter support */
#include "memory_.h"
#include "ghost.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, and 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> <length|null> <CloseSource> .reusablestream <filter> */
/*
 * The file|string operand must be a "reusable source", either:
 *      - A string or bytestring;
 *      - A readable, positionable file stream;
 *      - A SubFileDecode filter with an empty EODString and a reusable
 *      source;
 *      - A reusable stream.
 */
private int make_rss(P8(i_ctx_t *i_ctx_p, os_ptr op, const byte * data,
			uint size, long offset,	long length,
			bool is_bytestring, bool close_source));
private int
zreusablestream(i_ctx_t *i_ctx_p)
{
    os_ptr op = osp;
    os_ptr source_op = op - 2;
    os_ptr length_op = op - 1;
    long length;
    bool close_source;
    int code;

    if (r_has_type(length_op, t_integer)) {
	length = length_op->value.intval;
	if (length < 0)
	    return_error(e_rangecheck);
    } else
	length = -1;
    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, 0L, (length < 0 ? size : length), false,
			close_source);
    } 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, 0L,
			(length < 0 ? size : length), true, close_source);
    } else {
	long offset = 0;
	stream *source;

	check_read_file(source, source_op);
rs:
	if (source->cbuf_string.data != 0) {
	    /* The data source is a string. */
	    long avail;

	    offset += stell(source);
	    savailable(source, &avail);
	    if (avail < 0)
		avail = 0;
	    code = make_rss(i_ctx_p, source_op, source->cbuf_string.data,
			    source->cbuf_string.size, offset, avail, false,
			    close_source);
	} else if (source->file != 0) {
	    /* The data source is a file. */
	    /****** NYI ******/
	    return_error(e_rangecheck);
	} else if (source->state->template == &s_SFD_template) {
	    /* The data source is a SubFileDecode filter. */
	    const stream_SFD_state *const sfd_state =
	    (const stream_SFD_state *)source->state;

	    if (sfd_state->eod.size != 0)
		return_error(e_rangecheck);
	    if (sfd_state->count != 0) {
		long left = sfd_state->count + sbufavailable(source);

		if (left < length)
		    length = left;
	    }
	    source = source->strm;
	    goto rs;
	}
	else {
	    /****** REUSABLE CASE IS NYI ******/
	    return_error(e_rangecheck);
	}
    }
    if (code >= 0)
	pop(2);
    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,
	 long offset, long length, bool is_bytestring, bool close_source)
{
    stream *s;

    /****** SELECT CORRECT VM FOR ALLOCATION ******/
    s = file_alloc_stream(imemory, "make_rss");
    if (s == 0)
	return_error(e_VMerror);
    sread_string_reusable(s, data + offset, min(length, size - offset));
    if (is_bytestring)
	s->cbuf_string.data = 0;	/* byte array, not string */
    /****** DO WHAT WITH close_source ? ******/
    make_stream_file(op, s, "r");
    return 0;
}

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

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