/*
 * Copyright (C) 2012 Grigori Goronzy <greg@kinoho.net>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <stdio.h>
#include <stdlib.h>
#include "ucdn.h"

typedef struct {
	unsigned char category;
	unsigned char combining;
	unsigned char bidi_class;
	unsigned char mirrored;
	unsigned char east_asian_width;
	unsigned char normalization_check;
	unsigned char script;
} UCDRecord;

typedef struct {
	unsigned short from, to;
} MirrorPair;

typedef struct {
	unsigned int start;
	short count, index;
} Reindex;

#include "unicodedata_db.h"

/* constants required for Hangul (de)composition */
#define SBASE 0xAC00
#define LBASE 0x1100
#define VBASE 0x1161
#define TBASE 0x11A7
#define SCOUNT 11172
#define LCOUNT 19
#define VCOUNT 21
#define TCOUNT 28
#define NCOUNT (VCOUNT * TCOUNT)

static const UCDRecord *get_ucd_record(unsigned int code)
{
	int index, offset;

	if (code >= 0x110000)
		index = 0;
	else {
		index = index0[code >> (SHIFT1+SHIFT2)] << SHIFT1;
		offset = (code >> SHIFT2) & ((1<<SHIFT1) - 1);
		index = index1[index + offset] << SHIFT2;
		offset = code & ((1<<SHIFT2) - 1);
		index = index2[index + offset];
	}

	return &ucd_records[index];
}

static const unsigned short *get_decomp_record(unsigned int code)
{
	int index, offset;

	if (code >= 0x110000)
		index = 0;
	else {
		index = decomp_index0[code >> (DECOMP_SHIFT1+DECOMP_SHIFT2)]
			<< DECOMP_SHIFT1;
		offset = (code >> DECOMP_SHIFT2) & ((1<<DECOMP_SHIFT1) - 1);
		index = decomp_index1[index + offset] << DECOMP_SHIFT2;
		offset = code & ((1<<DECOMP_SHIFT2) - 1);
		index = decomp_index2[index + offset];
	}

	return &decomp_data[index];
}

static int get_comp_index(unsigned int code, const Reindex *idx)
{
	int i;

	for (i = 0; idx[i].start; i++) {
		const Reindex *cur = &idx[i];
		if (code < cur->start)
			return -1;
		if (code <= cur->start + cur->count) {
			return cur->index + (code - cur->start);
		}
	}

	return -1;
}

static int compare_mp(const void *a, const void *b)
{
	MirrorPair *mpa = (MirrorPair *)a;
	MirrorPair *mpb = (MirrorPair *)b;
	return mpa->from - mpb->from;
}

static int hangul_pair_decompose(unsigned int code, unsigned int *a, unsigned int *b)
{
	int si = code - SBASE;

	if (si < 0 || si >= SCOUNT)
		return 0;

	if (si % TCOUNT) {
		/* LV,T */
		*a = SBASE + (si / TCOUNT) * TCOUNT;
		*b = TBASE + (si % TCOUNT);
		return 3;
	} else {
		/* L,V */
		*a = LBASE + (si / NCOUNT);
		*b = VBASE + (si % NCOUNT) / TCOUNT;
		return 2;
	}
}

static int hangul_pair_compose(unsigned int *code, unsigned int a, unsigned int b)
{
	if (b < VBASE || b >= (TBASE + TCOUNT))
		return 0;

	if ((a < LBASE || a >= (LBASE + LCOUNT))
			&& (a < SBASE || a >= (SBASE + SCOUNT)))
		return 0;

	if (a >= SBASE) {
		/* LV,T */
		*code = a + (b - TBASE);
		return 3;
	} else {
		/* L,V */
		int li = a - LBASE;
		int vi = b - VBASE;
		*code = SBASE + li * NCOUNT + vi * TCOUNT;
		return 2;
	}
}

static unsigned int decode_utf16(const unsigned short **code_ptr)
{
	const unsigned short *code = *code_ptr;

	if ((code[0] & 0xd800) != 0xd800) {
		*code_ptr += 1;
		return (unsigned int)code[0];
	} else {
		*code_ptr += 2;
		return 0x10000 + ((unsigned int)code[1] - 0xdc00) +
			(((unsigned int)code[0] - 0xd800) << 10);
	}
}

const char *ucdn_get_unicode_version(void)
{
	return UNIDATA_VERSION;
}

int ucdn_get_combining_class(unsigned int code)
{
	return get_ucd_record(code)->combining;
}

int ucdn_get_east_asian_width(unsigned int code)
{
	return get_ucd_record(code)->east_asian_width;
}

int ucdn_get_general_category(unsigned int code)
{
	return get_ucd_record(code)->category;
}

int ucdn_get_bidi_class(unsigned int code)
{
	return get_ucd_record(code)->bidi_class;
}

int ucdn_get_mirrored(unsigned int code)
{
	return get_ucd_record(code)->mirrored;
}

int ucdn_get_script(unsigned int code)
{
	return get_ucd_record(code)->script;
}

unsigned int ucdn_mirror(unsigned int code)
{
	MirrorPair mp = {0};
	MirrorPair *res;

	if (get_ucd_record(code)->mirrored == 0)
		return code;

	mp.from = (unsigned short)code;
	res = bsearch(&mp, mirror_pairs, BIDI_MIRROR_LEN, sizeof(MirrorPair),
			compare_mp);

	if (res == NULL)
		return code;
	else
		return res->to;
}

int ucdn_decompose(unsigned int code, unsigned int *a, unsigned int *b)
{
	const unsigned short *rec;
	int len;

	if (hangul_pair_decompose(code, a, b))
		return 1;

	rec = get_decomp_record(code);
	len = rec[0] >> 8;

	if ((rec[0] & 0xff) != 0 || len == 0)
		return 0;

	rec++;
	*a = decode_utf16(&rec);
	if (len > 1)
		*b = decode_utf16(&rec);
	else
		*b = 0;

	return 1;
}

int ucdn_compose(unsigned int *code, unsigned int a, unsigned int b)
{
	int l, r, index, indexi, offset;

	if (hangul_pair_compose(code, a, b))
		return 1;

	l = get_comp_index(a, nfc_first);
	r = get_comp_index(b, nfc_last);

	if (l < 0 || r < 0)
		return 0;

	indexi = l * TOTAL_LAST + r;
	index = comp_index0[indexi >> (COMP_SHIFT1+COMP_SHIFT2)] << COMP_SHIFT1;
	offset = (indexi >> COMP_SHIFT2) & ((1<<COMP_SHIFT1) - 1);
	index = comp_index1[index + offset] << COMP_SHIFT2;
	offset = indexi & ((1<<COMP_SHIFT2) - 1);
	*code = comp_data[index + offset];

	return *code != 0;
}

int ucdn_compat_decompose(unsigned int code, unsigned int *decomposed)
{
	int i, len;
	const unsigned short *rec = get_decomp_record(code);
	len = rec[0] >> 8;

	if (len == 0)
		return 0;

	rec++;
	for (i = 0; i < len; i++)
		decomposed[i] = decode_utf16(&rec);

	return len;
}
