/*-
 * Copyright (c)2015 Takehiko NOZAKI,
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>

#include <sys/endian.h>
#include <sys/queue.h>
#include <assert.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>

#include "citrus_namespace.h"
#include "citrus_bcs.h"
#include "citrus_module.h"
#include "citrus_hash.h"
#include "citrus_iconv.h"

#include "citrus_iconv_u8u32.h"

_CITRUS_ICONV_DECLS(iconv_u8u32);
_CITRUS_ICONV_DEF_OPS(iconv_u8u32);

#define _ENDIAN_UNKNOWN		0
#define _ENDIAN_BIG		1
#define _ENDIAN_LITTLE		2

struct bom {
	int byteorder;
	char ch[4];
	int order[4];
};

struct _citrus_iconv_u8u32_shared {
	int byteorder;
};

struct _citrus_iconv_u8u32_context {
	int byteorder;
};

static const char utf8len[] = {
/* 0x00 - 0x0f */ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
/* 0x10 - 0x1f */ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
/* 0x20 - 0x2f */ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
/* 0x30 - 0x3f */ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
/* 0x40 - 0x4f */ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
/* 0x50 - 0x5f */ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
/* 0x60 - 0x6f */ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
/* 0x70 - 0x7f */ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
/* 0x80 - 0x8f */ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* 0x90 - 0x9f */ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* 0xa0 - 0xaf */ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* 0xb0 - 0xbf */ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* 0xc0 - 0xcf */ 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
/* 0xd0 - 0xdf */ 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
/* 0xe0 - 0xef */ 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
/* 0xf0 - 0xff */ 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 0, 0,
};

static const char utf8mask[] = {
	0x00, /* dummy */
	0x7f, 0x1f, 0x0f, 0x07, 0x03, 0x01
};

static const struct bom big = {
	_ENDIAN_BIG,
	{ 0x00, 0x00, 0xfe, 0xff },
	{ 3, 2, 1, 0 }
};

static const struct bom little = {
	_ENDIAN_LITTLE,
	{ 0xff, 0xfe, 0x00, 0x00 },
	{ 0, 1, 2, 3 }
};

static const struct bom *bom[] = {
#if BYTE_ORDER == BIG_ENDIAN
	&big,
#else
	&little,
#endif
	&big, &little
};

static __inline size_t
ucs4len(int32_t ucs4)
{
	if ((ucs4 & ~0x7f) == 0) {
		return 1;
	} else if ((ucs4 & ~0x7ff) == 0) {
		return 2;
	} else if ((ucs4 & ~0xffff) == 0) {
		if (ucs4 < 0xd800 || ucs4 > 0xdfff)
			return 3;
	} else if ((ucs4 & ~0x1fffff) == 0) {
		return 4;
	} else if ((ucs4 & ~0x3ffffff) == 0) {
		return 5;
	} else if ((ucs4 & ~0x7fffffff) == 0) {
		return 6;
	}
	return 0;
}

int
_citrus_iconv_u8u32_iconv_getops(struct _citrus_iconv_ops *ops,
    size_t lenops, uint32_t expected_version)
{
	if (expected_version < _CITRUS_ICONV_ABI_VERSION || lenops < sizeof(*ops))
		return EINVAL;

	memcpy(ops, &_citrus_iconv_u8u32_iconv_ops,
	       sizeof(_citrus_iconv_u8u32_iconv_ops));

	return 0;
}

/* ---------------------------------------------------------------------- */

static int
/*ARGSUSED*/
_citrus_iconv_u8u32_iconv_init_shared(struct _citrus_iconv_shared *ci,
    const char * __restrict curdir,
    const char * __restrict src, const char * __restrict dst,
    const void * __restrict var, size_t lenvar)
{
	struct _citrus_iconv_u8u32_shared *shared;
	const char *p;

	shared = malloc(sizeof(*shared));
	if (shared == NULL)
		return errno;

	shared->byteorder = _ENDIAN_UNKNOWN;
	if (lenvar > 0) {
		p = (const char *)var;
		if (!_bcs_strncasecmp(p, "UTF32BE", lenvar))
			shared->byteorder = _ENDIAN_BIG;
		else if (!_bcs_strncasecmp(p, "UTF32LE", lenvar))
			shared->byteorder = _ENDIAN_LITTLE;
	}
	ci->ci_closure = (void *)shared;
	return 0;
}

static void
_citrus_iconv_u8u32_iconv_uninit_shared(struct _citrus_iconv_shared *ci)
{
	free(ci->ci_closure);
}

static int
_citrus_iconv_u8u32_iconv_init_context(struct _citrus_iconv *cv)
{
	const struct _citrus_iconv_u8u32_shared *shared;
	struct _citrus_iconv_u8u32_context *ctx;

	shared = cv->cv_shared->ci_closure;
	ctx = malloc(sizeof(*ctx));
        if (ctx == NULL)
                return errno;
	ctx->byteorder = shared->byteorder;
	cv->cv_closure = (void *)ctx;
	return 0;
}

static void
_citrus_iconv_u8u32_iconv_uninit_context(struct _citrus_iconv *cv)
{
	free(cv->cv_closure);
}

static int
_citrus_iconv_u8u32_iconv_convert(struct _citrus_iconv * __restrict cv,
    const char * __restrict * __restrict inp, size_t * __restrict inbytesp,
    char * __restrict * __restrict outp, size_t * __restrict outbytesp,
    uint32_t flags, size_t * __restrict invalids)
{
	const struct _citrus_iconv_u8u32_shared *shared;
	struct _citrus_iconv_u8u32_context *ctx;
	const char *in;
	char *out;
	size_t inbytes, outbytes, len, i;
	const struct bom *bp;
	int32_t ucs4;
	int ret;

	shared = cv->cv_shared->ci_closure;
	ctx = cv->cv_closure;

        if (inp == NULL || *inp == NULL) {
		if (outp == NULL || *outp == NULL)
			ctx->byteorder = shared->byteorder;
		*invalids = 0;
		return 0;
	}
	in = *inp;
	inbytes = *inbytesp;
	out = *outp;
	outbytes = *outbytesp;
	switch (ctx->byteorder) {
	case _ENDIAN_UNKNOWN:
		bp = bom[ctx->byteorder];
		if (outbytes < 4) {
			ret = E2BIG;
			goto fatal;
		}
		memcpy(out, bp->ch, 4);
		outbytes -=4, out += 4;
		ctx->byteorder = bp->byteorder;
		break;
	case _ENDIAN_BIG:
	case _ENDIAN_LITTLE:
		bp = bom[ctx->byteorder];
		break;
	default:
		ret = EILSEQ;
		goto fatal;
	}
	for (;;) {
		if (inbytes == 0)
			break;
		if (outbytes < 4) {
			ret = E2BIG;
			goto fatal;
		}
		len = utf8len[*in & 0xff];
		if (len == 0) {
			ret = EILSEQ;
			goto fatal;
		}
		if (inbytes < len) {
			ret = EINVAL;
			goto fatal;
		}
		ucs4 = in[0] & utf8mask[len];
		for (i = 1; i < len; ++i) {
			if ((in[i] & 0xc0) != 0x80) {
				ret = EILSEQ;
				goto fatal;
			}
			ucs4 <<= 6;
			ucs4 |= in[i] & 0x3f;
		}
		if (ucs4len(ucs4) != len) {
			ret = EILSEQ;
			goto fatal;
		}
		out[bp->order[0]] =  ucs4        & 0xff;
		out[bp->order[1]] = (ucs4 >>  8) & 0xff;
		out[bp->order[2]] = (ucs4 >> 16) & 0xff;
		out[bp->order[3]] = (ucs4 >> 24) & 0xff;
		inbytes -= len, in += len;
		outbytes -= 4, out += 4;
	}
	ret = 0;
fatal:
	*inp = in;
	*inbytesp = inbytes;
	*outp = out;
	*outbytesp = outbytes;
	*invalids = 0;
	return ret;
}