/*
 * Copyright 2001-2014, Axel Dörfler, axeld@pinc-software.de.
 * Copyright 2010, Clemens Zeidler <haiku@clemens-zeidler.de>
 * Copyright 2011, Ingo Weinhold, ingo_weinhold@gmx.de.
 * This file may be used under the terms of the MIT License.
 */


// This needs to be the first include because of the fs shell API wrapper
#include <algorithm>

#include <file_systems/QueryParserUtils.h>

#ifndef FS_SHELL
#	include <string.h>

#	include <TypeConstants.h>
#endif


namespace QueryParser {


template<typename Key>
static inline int
compare_integral(const Key& a, const Key& b)
{
	if (a < b)
		return -1;
	if (a > b)
		return 1;
	return 0;
}


// #pragma mark -


void
skipWhitespace(const char** expr, int32 skip)
{
	const char* string = (*expr) + skip;
	while (*string == ' ' || *string == '\t') string++;
	*expr = string;
}


void
skipWhitespaceReverse(const char** expr, const char* stop)
{
	const char* string = *expr;
	while (string > stop && (*string == ' ' || *string == '\t'))
		string--;
	*expr = string;
}


int
compareKeys(uint32 type, const void* key1, size_t length1, const void* key2,
	size_t length2)
{
	switch (type) {
		case B_INT32_TYPE:
			return compare_integral(*(int32*)key1, *(int32*)key2);
		case B_UINT32_TYPE:
			return compare_integral(*(uint32*)key1, *(uint32*)key2);
		case B_INT64_TYPE:
			return compare_integral(*(int64*)key1, *(int64*)key2);
		case B_UINT64_TYPE:
			return compare_integral(*(uint64*)key1, *(uint64*)key2);
		case B_FLOAT_TYPE:
			return compare_integral(*(float*)key1, *(float*)key2);
		case B_DOUBLE_TYPE:
			return compare_integral(*(double*)key1, *(double*)key2);
		case B_STRING_TYPE:
		case B_MIME_STRING_TYPE:
		{
			int result = strncmp((const char*)key1, (const char*)key2,
				std::min(length1, length2));
			if (result == 0) {
				result = compare_integral(strnlen((const char*)key1, length1),
					strnlen((const char*)key2, length2));
			}
			return result;
		}
	}
	return -1;
}


//	#pragma mark -


uint32
utf8ToUnicode(const char** string)
{
	uint8* bytes = (uint8*)*string;
	int32 length;
	uint8 mask = 0x1f;

	switch (bytes[0] & 0xf0) {
		case 0xc0:
		case 0xd0:
			length = 2;
			break;
		case 0xe0:
			length = 3;
			break;
		case 0xf0:
			mask = 0x0f;
			length = 4;
			break;
		default:
			// valid 1-byte character
			// and invalid characters
			(*string)++;
			return bytes[0];
	}
	uint32 c = bytes[0] & mask;
	int32 i = 1;
	for (; i < length && (bytes[i] & 0x80) > 0; i++)
		c = (c << 6) | (bytes[i] & 0x3f);

	if (i < length) {
		// invalid character
		(*string)++;
		return (uint32)bytes[0];
	}
	*string += length;
	return c;
}


int32
getFirstPatternSymbol(const char* string)
{
	char c;

	for (int32 index = 0; (c = *string++); index++) {
		if (c == '*' || c == '?' || c == '[')
			return index;
	}
	return -1;
}


status_t
isValidPattern(const char* pattern)
{
	while (*pattern) {
		switch (*pattern++) {
			case '\\':
				// the escape character must not be at the end of the pattern
				if (!*pattern++)
					return PATTERN_INVALID_ESCAPE;
				break;

			case '[':
				if (pattern[0] == ']' || !pattern[0])
					return PATTERN_INVALID_SET;

				while (*pattern != ']') {
					if (*pattern == '\\' && !*++pattern)
						return PATTERN_INVALID_ESCAPE;

					if (!*pattern)
						return PATTERN_INVALID_SET;

					if (pattern[0] == '-' && pattern[1] == '-')
						return PATTERN_INVALID_RANGE;

					pattern++;
				}
				break;
		}
	}
	return B_OK;
}


/*!	Matches the string against the given wildcard pattern.
	Returns either MATCH_OK, or NO_MATCH when everything went fine, or
	values < 0 (see enum at the top of Query.cpp) if an error occurs.

	The pattern matching is roughly based on code originally written
	by J. Kercheval, and on code written by Kenneth Almquist, though
	it shares no code.
*/
status_t
matchString(const char* pattern, const char* string)
{
	while (*pattern) {
		// end of string == valid end of pattern?
		if (!string[0]) {
			while (pattern[0] == '*')
				pattern++;
			return !pattern[0] ? MATCH_OK : NO_MATCH;
		}

		switch (*pattern++) {
			case '?':
			{
				// match exactly one UTF-8 character; we are
				// not interested in the result
				utf8ToUnicode(&string);
				break;
			}

			case '*':
			{
				// compact pattern
				while (true) {
					if (pattern[0] == '?') {
						if (!*++string)
							return NO_MATCH;
					} else if (pattern[0] != '*')
						break;

					pattern++;
				}

				// if the pattern is done, we have matched the string
				if (!pattern[0])
					return MATCH_OK;

				while(true) {
					// we have removed all occurences of '*' and '?'
					if (pattern[0] == string[0]
						|| pattern[0] == '['
						|| pattern[0] == '\\') {
						status_t status = matchString(pattern, string);
						if (status < B_OK || status == MATCH_OK)
							return status;
					}

					// we could be nice here and just jump to the next
					// UTF-8 character - but we wouldn't gain that much
					// and it'd be slower (since we're checking for
					// equality before entering the recursion)
					if (!*++string)
						return NO_MATCH;
				}
				break;
			}

			case '[':
			{
				bool invert = false;
				if (pattern[0] == '^' || pattern[0] == '!') {
					invert = true;
					pattern++;
				}

				if (!pattern[0] || pattern[0] == ']')
					return MATCH_BAD_PATTERN;

				uint32 c = utf8ToUnicode(&string);
				bool matched = false;

				while (pattern[0] != ']') {
					if (!pattern[0])
						return MATCH_BAD_PATTERN;

					if (pattern[0] == '\\')
						pattern++;

					uint32 first = utf8ToUnicode(&pattern);

					// Does this character match, or is this a range?
					if (first == c) {
						matched = true;
						break;
					} else if (pattern[0] == '-' && pattern[1] != ']'
							&& pattern[1]) {
						pattern++;

						if (pattern[0] == '\\') {
							pattern++;
							if (!pattern[0])
								return MATCH_BAD_PATTERN;
						}
						uint32 last = utf8ToUnicode(&pattern);

						if (c >= first && c <= last) {
							matched = true;
							break;
						}
					}
				}

				if (invert)
					matched = !matched;

				if (matched) {
					while (pattern[0] != ']') {
						if (!pattern[0])
							return MATCH_BAD_PATTERN;
						pattern++;
					}
					pattern++;
					break;
				}
				return NO_MATCH;
			}

            case '\\':
				if (!pattern[0])
					return MATCH_BAD_PATTERN;
				// supposed to fall through
			default:
				if (pattern[-1] != string[0])
					return NO_MATCH;
				string++;
				break;
		}
	}

	if (string[0])
		return NO_MATCH;

	return MATCH_OK;
}


}	// namespace QueryParser