/*
   +----------------------------------------------------------------------+
   | Copyright © The PHP Group and Contributors.                          |
   +----------------------------------------------------------------------+
   | This source file is subject to the Modified BSD License that is      |
   | bundled with this package in the file LICENSE, and is available      |
   | through the World Wide Web at <https://www.php.net/license/>.        |
   |                                                                      |
   | SPDX-License-Identifier: BSD-3-Clause                                |
   +----------------------------------------------------------------------+
   | Author: Wez Furlong (wez@thebrainroom.com)                           |
   +----------------------------------------------------------------------+

	Based on code from ucdata-2.5, which has the following Copyright:

	Copyright 2001 Computing Research Labs, New Mexico State University

	Permission is hereby granted, free of charge, to any person obtaining a
	copy of this software and associated documentation files (the "Software"),
	to deal in the Software without restriction, including without limitation
	the rights to use, copy, modify, merge, publish, distribute, sublicense,
	and/or sell copies of the Software, and to permit persons to whom the
	Software is furnished to do so, subject to the following conditions:

	The above copyright notice and this permission notice shall be included in
	all copies or substantial portions of the Software.
*/

#include "php.h"

/* include case folding data generated from the official UnicodeData.txt file */
#include "mbstring.h"
#include "php_unicode.h"
#include "unicode_data.h"

extern const mbfl_encoding mbfl_encoding_8859_9;

ZEND_EXTERN_MODULE_GLOBALS(mbstring)

static bool prop_lookup(unsigned long code, unsigned long n)
{
	long l = _ucprop_offsets[n];
	long r = _ucprop_offsets[n + 1] - 1;
	while (l <= r) {
		/*
		 * Determine a "mid" point and adjust to make sure the mid point is at
		 * the beginning of a range pair.
		 */
		long m = (l + r) >> 1;
		m -= (m & 1);
		if (code > _ucprop_ranges[m + 1])
			l = m + 2;
		else if (code < _ucprop_ranges[m])
			r = m - 2;
		else
			return true;
	}
	return false;

}

MBSTRING_API bool php_unicode_is_prop1(unsigned long code, int prop)
{
	return prop_lookup(code, prop);
}

MBSTRING_API bool php_unicode_is_prop(unsigned long code, ...)
{
	bool result = false;
	va_list va;
	va_start(va, code);

	while (1) {
		int prop = va_arg(va, int);
		if (prop < 0) {
			break;
		}

		if (prop_lookup(code, prop)) {
			result = true;
			break;
		}
	}

	va_end(va);
	return result;
}

static inline unsigned mph_hash(unsigned d, unsigned x) {
	x ^= d;
	x = ((x >> 16) ^ x) * 0x45d9f3b;
	return x;
}

#define CODE_NOT_FOUND ((unsigned) -1)

static inline unsigned mph_lookup(
		unsigned code,
		const short *g_table, unsigned g_table_size,
		const unsigned *table, unsigned table_size)
{
	short g = g_table[mph_hash(0, code) % g_table_size];

	unsigned idx;
	if (g <= 0) {
		idx = -g;
	} else {
		idx = mph_hash(g, code) % table_size;
	}

	if (table[2*idx] == code) {
		return table[2*idx + 1];
	}
	return CODE_NOT_FOUND;
}

#define CASE_LOOKUP(code, type) \
	mph_lookup(code, _uccase_##type##_g, _uccase_##type##_g_size, \
			_uccase_##type##_table, _uccase_##type##_table_size)

static unsigned php_unicode_toupper_raw(unsigned code, const mbfl_encoding *enc)
{
	/* After the ASCII characters, the first codepoint with an uppercase version
	 * is 0xB5 (MICRO SIGN) */
	if (code < 0xB5) {
		/* Fast path for ASCII */
		if (code >= 0x61 && code <= 0x7A) {
			if (UNEXPECTED(enc == &mbfl_encoding_8859_9 && code == 0x69)) {
				return 0x130;
			}
			return code - 0x20;
		}
		return code;
	} else {
		unsigned new_code = CASE_LOOKUP(code, upper);
		if (new_code != CODE_NOT_FOUND) {
			return new_code;
		}
		return code;
	}
}

static unsigned php_unicode_tolower_raw(unsigned code, const mbfl_encoding *enc)
{
	/* After the ASCII characters, the first codepoint with a lowercase version
	 * is 0xC0 (LATIN CAPITAL LETTER A WITH GRAVE) */
	if (code < 0xC0) {
		/* Fast path for ASCII */
		if (code >= 0x41 && code <= 0x5A) {
			if (UNEXPECTED(enc == &mbfl_encoding_8859_9 && code == 0x0049L)) {
				return 0x0131L;
			}
			return code + 0x20;
		}
		return code;
	} else {
		unsigned new_code = CASE_LOOKUP(code, lower);
		if (new_code != CODE_NOT_FOUND) {
			if (UNEXPECTED(enc == &mbfl_encoding_8859_9 && code == 0x130)) {
				return 0x69;
			}
			return new_code;
		}
		return code;
	}
}

static unsigned php_unicode_totitle_raw(unsigned code, const mbfl_encoding *enc)
{
	unsigned new_code = CASE_LOOKUP(code, title);
	if (new_code != CODE_NOT_FOUND) {
		return new_code;
	}

	/* No dedicated title-case variant, use to-upper instead */
	return php_unicode_toupper_raw(code, enc);
}

static unsigned php_unicode_tofold_raw(unsigned code, const mbfl_encoding *enc)
{
	/* After the ASCII characters, the first codepoint with an special case-folded version
	 * is 0xB5 (MICRO SIGN) */
	if (code < 0xB5) {
		/* Fast path for ASCII */
		if (code >= 0x41 && code <= 0x5A) {
			if (UNEXPECTED(enc == &mbfl_encoding_8859_9 && code == 0x49)) {
				return 0x131;
			}
			return code + 0x20;
		}
		return code;
	} else {
		unsigned new_code = CASE_LOOKUP(code, fold);
		if (new_code != CODE_NOT_FOUND) {
			if (UNEXPECTED(enc == &mbfl_encoding_8859_9 && code == 0x130)) {
				return 0x69;
			}
			return new_code;
		}
		return code;
	}
}

static inline unsigned php_unicode_tolower_simple(unsigned code, const mbfl_encoding *enc) {
	code = php_unicode_tolower_raw(code, enc);
	if (UNEXPECTED(code > 0xffffff)) {
		return _uccase_extra_table[code & 0xffffff];
	}
	return code;
}
static inline unsigned php_unicode_toupper_simple(unsigned code, const mbfl_encoding *enc) {
	code = php_unicode_toupper_raw(code, enc);
	if (UNEXPECTED(code > 0xffffff)) {
		return _uccase_extra_table[code & 0xffffff];
	}
	return code;
}
static inline unsigned php_unicode_totitle_simple(unsigned code, const mbfl_encoding *enc) {
	code = php_unicode_totitle_raw(code, enc);
	if (UNEXPECTED(code > 0xffffff)) {
		return _uccase_extra_table[code & 0xffffff];
	}
	return code;
}
static inline unsigned php_unicode_tofold_simple(unsigned code, const mbfl_encoding *enc) {
	code = php_unicode_tofold_raw(code, enc);
	if (UNEXPECTED(code > 0xffffff)) {
		return _uccase_extra_table[code & 0xffffff];
	}
	return code;
}

static uint32_t *emit_special_casing_sequence(uint32_t w, uint32_t *out)
{
	unsigned int len = w >> 24;
	const unsigned int *p = &_uccase_extra_table[w & 0xFFFFFF];
	while (len--) {
		*out++ = *++p;
	}
	return out;
}

/* Used when determining whether special casing rules should be applied to Greek letter sigma */
static bool scan_ahead_for_cased_letter(unsigned char *in, size_t in_len, unsigned int state, const mbfl_encoding *encoding)
{
	uint32_t wchar_buf[64];

	while (in_len) {
		size_t out_len = encoding->to_wchar(&in, &in_len, wchar_buf, 64, &state);
		ZEND_ASSERT(out_len <= 64);
		for (unsigned int i = 0; i < out_len; i++) {
			uint32_t w = wchar_buf[i];
			if (php_unicode_is_cased(w)) {
				return true;
			}
			if (!php_unicode_is_case_ignorable(w)) {
				return false;
			}
		}
	}

	return false;
}

/* Used when determining whether special casing rules should be applied to Greek letter sigma */
static bool scan_back_for_cased_letter(uint32_t *begin, uint32_t *end)
{
	if (end != NULL) {
		while (--end >= begin) {
			uint32_t w = *end;
			if (php_unicode_is_cased(w)) {
				return true;
			}
			if (!php_unicode_is_case_ignorable(w)) {
				return false;
			}
		}
	}
	return false;
}

MBSTRING_API zend_string *php_unicode_convert_case(php_case_mode case_mode, const char *srcstr, size_t in_len, const mbfl_encoding *src_encoding, const mbfl_encoding *dst_encoding, int illegal_mode, uint32_t illegal_substchar)
{
	/* A Unicode codepoint can expand out to up to 3 codepoints when uppercased, lowercased, or title cased
	 * See http://www.unicode.org/Public/UNIDATA/SpecialCasing.txt */
	uint32_t wchar_buf[64], converted_buf[192];
	unsigned int state = 0, title_mode = 0;
	unsigned char *in = (unsigned char*)srcstr;
	/* In rare cases, we need to scan backwards through the previously converted codepoints to see
	 * if special conversion rules should be used for the Greek letter sigma */
	uint32_t *converted_end = NULL;

	mb_convert_buf buf;
	mb_convert_buf_init(&buf, in_len + 1, illegal_substchar, illegal_mode);

	while (in_len) {
		size_t out_len = src_encoding->to_wchar(&in, &in_len, wchar_buf, 64, &state);
		ZEND_ASSERT(out_len <= 64);
		uint32_t *p = converted_buf;

		/* In all cases, handle invalid characters early, as we assign special meaning to codepoints > 0xFFFFFF */
		switch (case_mode) {
		case PHP_UNICODE_CASE_UPPER_SIMPLE:
			for (size_t i = 0; i < out_len; i++) {
				uint32_t w = wchar_buf[i];
				*p++ = (UNEXPECTED(w > 0xFFFFFF)) ? w : php_unicode_toupper_simple(w, src_encoding);
			}
			break;

		case PHP_UNICODE_CASE_LOWER_SIMPLE:
			for (size_t i = 0; i < out_len; i++) {
				uint32_t w = wchar_buf[i];
				*p++ = (UNEXPECTED(w > 0xFFFFFF)) ? w : php_unicode_tolower_simple(w, src_encoding);
			}
			break;

		case PHP_UNICODE_CASE_FOLD_SIMPLE:
			for (size_t i = 0; i < out_len; i++) {
				uint32_t w = wchar_buf[i];
				*p++ = (UNEXPECTED(w > 0xFFFFFF)) ? w : php_unicode_tofold_simple(w, src_encoding);
			}
			break;

		case PHP_UNICODE_CASE_TITLE_SIMPLE:
			for (size_t i = 0; i < out_len; i++) {
				uint32_t w = wchar_buf[i];
				if (UNEXPECTED(w > 0xFFFFFF)) {
					*p++ = w;
					continue;
				}
				*p++ = title_mode ? php_unicode_tolower_simple(w, src_encoding) : php_unicode_totitle_simple(w, src_encoding);
				if (!php_unicode_is_case_ignorable(w)) {
					title_mode = php_unicode_is_cased(w);
				}
			}
			break;

		case PHP_UNICODE_CASE_UPPER:
			for (size_t i = 0; i < out_len; i++) {
				uint32_t w = wchar_buf[i];
				if (UNEXPECTED(w > 0xFFFFFF)) {
					*p++ = w;
					continue;
				}
				w = php_unicode_toupper_raw(w, src_encoding);
				if (UNEXPECTED(w > 0xFFFFFF)) {
					p = emit_special_casing_sequence(w, p);
				} else {
					*p++ = w;
				}
			}
			break;

		case PHP_UNICODE_CASE_LOWER:
			for (size_t i = 0; i < out_len; i++) {
				uint32_t w = wchar_buf[i];
				if (UNEXPECTED(w > 0xFFFFFF)) {
					*p++ = w;
					continue;
				}
				if (w == 0x3A3) {
					/* For Greek capital letter sigma, there is a special casing rule;
					 * if it is the last letter in a word, it should be downcased to U+03C2
					 * (GREEK SMALL LETTER FINAL SIGMA)
					 * Specifically, we need to check if this codepoint is preceded by any
					 * number of case-ignorable codepoints, preceded by a cased letter, AND
					 * is NOT followed by any number of case-ignorable codepoints followed
					 * by a cased letter.
					 * Ref: http://www.unicode.org/reports/tr21/tr21-5.html
					 * Ref: https://unicode.org/Public/UNIDATA/SpecialCasing.txt
					 *
					 * While the special casing rules say we should scan backwards through "any number"
					 * of case-ignorable codepoints, that is a great implementation burden
					 * It would basically mean we need to keep all the codepoints in a big buffer
					 * during this conversion operation, but we don't want to do that (to reduce the
					 * amount of temporary scratch memory used)
					 * Hence, we only scan back through the codepoints in wchar_buf, and if we hit the
					 * beginning of the buffer, whatever codepoints have not yet been overwritten in
					 * the latter part of converted_buf */
					int j = i - 1;
					while (j >= 0 && php_unicode_is_case_ignorable(wchar_buf[j])) {
						j--;
					}
					if (j >= 0 ? php_unicode_is_cased(wchar_buf[j]) : scan_back_for_cased_letter(p, converted_end)) {
						/* Now scan ahead to look for a cased letter */
						j = i + 1;
						while (j < out_len && php_unicode_is_case_ignorable(wchar_buf[j])) {
							j++;
						}
						/* If we hit the end of wchar_buf, convert more of the input string into
						 * codepoints and continue scanning */
						if (j >= out_len ? !scan_ahead_for_cased_letter(in, in_len, state, src_encoding) : !php_unicode_is_cased(wchar_buf[j])) {
							*p++ = 0x3C2;
							continue;
						}
					}
				}
				w = php_unicode_tolower_raw(w, src_encoding);
				if (UNEXPECTED(w > 0xFFFFFF)) {
					p = emit_special_casing_sequence(w, p);
				} else {
					*p++ = w;
				}
			}
			break;

		case PHP_UNICODE_CASE_FOLD:
			for (size_t i = 0; i < out_len; i++) {
				uint32_t w = wchar_buf[i];
				if (UNEXPECTED(w > 0xFFFFFF)) {
					*p++ = w;
					continue;
				}
				w = php_unicode_tofold_raw(w, src_encoding);
				if (UNEXPECTED(w > 0xFFFFFF)) {
					p = emit_special_casing_sequence(w, p);
				} else {
					*p++ = w;
				}
			}
			break;

		case PHP_UNICODE_CASE_TITLE:
			for (size_t i = 0; i < out_len; i++) {
				uint32_t w = wchar_buf[i];
				if (UNEXPECTED(w > 0xFFFFFF)) {
					*p++ = w;
					continue;
				}
				uint32_t w2;
				if (title_mode) {
					if (w == 0x3A3) {
						int j = i - 1;
						while (j >= 0 && php_unicode_is_case_ignorable(wchar_buf[j])) {
							j--;
						}
						if (j >= 0 ? php_unicode_is_cased(wchar_buf[j]) : scan_back_for_cased_letter(p, converted_end)) {
							j = i + 1;
							while (j < out_len && php_unicode_is_case_ignorable(wchar_buf[j])) {
								j++;
							}
							if (j >= out_len ? !scan_ahead_for_cased_letter(in, in_len, state, src_encoding) : !php_unicode_is_cased(wchar_buf[j])) {
								*p++ = 0x3C2;
								goto set_title_mode;
							}
						}
					}
					w2 = php_unicode_tolower_raw(w, src_encoding);
				} else {
					w2 = php_unicode_totitle_raw(w, src_encoding);
				}
				if (UNEXPECTED(w2 > 0xFFFFFF)) {
					p = emit_special_casing_sequence(w2, p);
				} else {
					*p++ = w2;
				}
set_title_mode:
				if (!php_unicode_is_case_ignorable(w)) {
					title_mode = php_unicode_is_cased(w);
				}
			}
			break;

			default: ZEND_UNREACHABLE();
		}

		converted_end = p;
		ZEND_ASSERT(p - converted_buf <= 192);
		dst_encoding->from_wchar(converted_buf, p - converted_buf, &buf, !in_len);
	}

	return mb_convert_buf_result(&buf, dst_encoding);
}
