/** Implementation of NSRegualrExpression for GNUStep

   Copyright (C) 2010 Free Software Foundation, Inc.

   This file is part of the GNUstep Base Library.

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2 of the License, or (at your option) any later version.

   This library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with this library; if not, write to the Free
   Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
   Boston, MA 02111 USA.

   $Date: 2010-09-18 16:09:58 +0100 (Sat, 18 Sep 2010) $ $Revision: 31371 $
   */

#import "common.h"

#if GS_USE_ICU == 1
#include "unicode/uregex.h"
#if (U_ICU_VERSION_MAJOR_NUM > 4 || (U_ICU_VERSION_MAJOR_NUM == 4 && U_ICU_VERSION_MINOR_NUM >= 4))
#define NSRegularExpressionWorks
#define GSREGEXTYPE URegularExpression
#import "GSICUString.h"
#endif //U_ICU_VERSION_MAJOR_NUM > 4 || (U_ICU_VERSION_MAJOR_NUM == 4 && U_ICU_VERSION_MINOR_NUM >= 4))
#endif //HAV_ICU

#import "Foundation/NSArray.h"
#import "Foundation/NSCoder.h"
#import "Foundation/NSException.h"
#import "Foundation/NSRegularExpression.h"
#import "Foundation/NSTextCheckingResult.h"

#ifdef NSRegularExpressionWorks
/**
 * To be helpful, Apple decided to define a set of flags that mean exactly the
 * same thing as the URegexpFlags enum in libicu, but have different values.
 * This was completely stupid, but we probably have to live with it.  We could
 * in theory use the libicu values directly (that would be sensible), but that
 * would break any code that didn't correctly use the symbolic constants.
 */
uint32_t
NSRegularExpressionOptionsToURegexpFlags(NSRegularExpressionOptions opts)
{
  uint32_t flags = 0;

  if (opts & NSRegularExpressionCaseInsensitive)
    {
      flags |= UREGEX_CASE_INSENSITIVE;
    }
  if (opts & NSRegularExpressionAllowCommentsAndWhitespace)
    {
      flags |= UREGEX_COMMENTS;
    }
  if (opts & NSRegularExpressionIgnoreMetacharacters)
    {
    flags |= UREGEX_LITERAL;
    }
  if (opts & NSRegularExpressionDotMatchesLineSeparators)
    {
      flags |= UREGEX_DOTALL;
    }
  if (opts & NSRegularExpressionAnchorsMatchLines)
    {
      flags |= UREGEX_MULTILINE;
    }
  if (opts & NSRegularExpressionUseUnixLineSeparators)
    {
      flags |= UREGEX_UNIX_LINES;
    }
  if (opts & NSRegularExpressionUseUnicodeWordBoundaries)
    {
      flags |= UREGEX_UWORD;
    }
  return flags;
}
#endif

@implementation NSRegularExpression

+ (NSRegularExpression*) regularExpressionWithPattern: (NSString*)aPattern
  options: (NSRegularExpressionOptions)opts
  error: (NSError**)e
{
  return [[[self alloc] initWithPattern: aPattern
				options: opts
				  error: e] autorelease];
}

- (id) initWithPattern: (NSString*)aPattern
	       options: (NSRegularExpressionOptions)opts
		 error: (NSError**)e
{
#ifdef NSRegularExpressionWorks
  uint32_t	flags = NSRegularExpressionOptionsToURegexpFlags(opts);
  UText		p = UTEXT_INITIALIZER;
  UParseError	pe = {0};
  UErrorCode	s = 0;

  UTextInitWithNSString(&p, aPattern);
  regex = uregex_openUText(&p, flags, &pe, &s);
  utext_close(&p);
  if (U_FAILURE(s))
    {
      // FIXME: Do something sensible with the error parameter.
      [self release];
      return nil;
    }
#endif
  ASSIGN(pattern, aPattern);
  options = opts;
  return self;
}

- (NSString*) pattern
{
  return pattern;
}

#ifdef NSRegularExpressionWorks
static UBool
callback(const void *context, int32_t steps)
{
  BOOL		stop = NO;
  GSRegexBlock	block = (GSRegexBlock)context;

  if (NULL == context)
    {
      return FALSE;
    }
  CALL_BLOCK(block, nil, NSMatchingProgress, &stop);
  return stop;
}

/**
 * Sets up a libicu regex object for use.  Note: the documentation states that
 * NSRegularExpression must be thread safe.  To accomplish this, we store a
 * prototype URegularExpression in the object, and then clone it in each
 * method.  This is required because URegularExpression, unlike
 * NSRegularExpression, is stateful, and sharing this state between threads
 * would break concurrent calls.
 */
static URegularExpression *
setupRegex(URegularExpression *regex,
  NSString *string,
  UText *txt,
  NSMatchingOptions options,
  NSRange range,
  GSRegexBlock block)
{
  UErrorCode		s = 0;
  URegularExpression	*r = uregex_clone(regex, &s);

  if (options & NSMatchingReportProgress)
    {
      uregex_setMatchCallback(r, callback, block, &s);
    }
  UTextInitWithNSString(txt, string);
  uregex_setUText(r, txt, &s);
  uregex_setRegion(r, range.location, range.location+range.length, &s);
  if (options & NSMatchingWithoutAnchoringBounds)
    {
      uregex_useAnchoringBounds(r, FALSE, &s);
    }
  if (options & NSMatchingWithTransparentBounds)
    {
      uregex_useTransparentBounds(r, TRUE, &s);
    }
  if (U_FAILURE(s))
    {
      uregex_close(r);
      return NULL;
    }
  return r;
}

static uint32_t
prepareResult(NSRegularExpression *regex,
  URegularExpression *r,
  NSRangePointer ranges,
  NSUInteger groups,
  UErrorCode *s)
{
  uint32_t	flags = 0;
  NSUInteger	i = 0;

  for (i = 0; i < groups; i++)
    {
      NSUInteger start = uregex_start(r, i, s);
      NSUInteger end = uregex_end(r, i, s);

      ranges[i] = NSMakeRange(start, end-start);
    }
  if (uregex_hitEnd(r, s))
    {
      flags |= NSMatchingHitEnd;
    }
  if (uregex_requireEnd(r, s))
    {
      flags |= NSMatchingRequiredEnd;
    }
  if (0 != *s)
    {
      flags |= NSMatchingInternalError;
    }
  return flags;
}
#endif

- (void) enumerateMatchesInString: (NSString*)string
                          options: (NSMatchingOptions)opts
                            range: (NSRange)range
                       usingBlock: (GSRegexBlock)block
{
#ifdef NSRegularExpressionWorks
  UErrorCode	s = 0;
  UText		txt = UTEXT_INITIALIZER;
  BOOL		stop = NO;
  URegularExpression *r = setupRegex(regex, string, &txt, opts, range, block);
  NSUInteger	groups = [self numberOfCaptureGroups] + 1;
  NSRange	ranges[groups];

  // Should this throw some kind of exception?
  if (NULL == r)
    {
      return;
    }
  if (opts & NSMatchingAnchored)
    {
      if (uregex_lookingAt(r, -1, &s) && (0 == s))
	{
	  // FIXME: Factor all of this out into prepareResult()
	  uint32_t		flags;
	  NSTextCheckingResult *result;

	  flags = prepareResult(self, r, ranges, groups, &s);
	  result = [NSTextCheckingResult
	    regularExpressionCheckingResultWithRanges: ranges
						count: groups
				    regularExpression: self];
	  CALL_BLOCK(block, result, flags, &stop);
	}
    }
  else
    {
      while (!stop && uregex_findNext(r, &s) && (0 == s))
	{
	  uint32_t		flags;
	  NSTextCheckingResult	*result;

	  flags = prepareResult(self, r, ranges, groups, &s);
	  result = [NSTextCheckingResult
	    regularExpressionCheckingResultWithRanges: ranges
						count: groups
				    regularExpression: self];
	  CALL_BLOCK(block, result, flags, &stop);
	}
    }
  if (opts & NSMatchingCompleted)
    {
      CALL_BLOCK(block, nil, NSMatchingCompleted, &stop);
    }
  utext_close(&txt);
  uregex_close(r);
#else
  //FIXME
  [NSException raise: NSInvalidArgumentException
              format: @"NSRegularExpression requires ICU 4.4 or later"];
#endif
}

/* The remaining methods are all meant to be wrappers around the primitive
 * method that takes a block argument.  Unfortunately, this is not really
 * possible when compiling with a compiler that doesn't support blocks.
 */
#if __has_feature(blocks)
- (NSUInteger) numberOfMatchesInString: (NSString*)string
                               options: (NSMatchingOptions)opts
                                 range: (NSRange)range

{
  __block NSUInteger	count = 0;

  opts &= ~NSMatchingReportProgress;
  opts &= ~NSMatchingReportCompletion;

  GSRegexBlock block =
    ^(NSTextCheckingResult *result, NSMatchingFlags flags, BOOL *stop)
    {
      count++;
    };
  [self enumerateMatchesInString: string
			 options: opts
			   range: range
		      usingBlock: block];
  return count;
}

- (NSTextCheckingResult*) firstMatchInString: (NSString*)string
                                     options: (NSMatchingOptions)opts
                                       range: (NSRange)range
{
  __block NSTextCheckingResult *r = nil;

  opts &= ~NSMatchingReportProgress;
  opts &= ~NSMatchingReportCompletion;

  GSRegexBlock block =
    ^(NSTextCheckingResult *result, NSMatchingFlags flags, BOOL *stop)
    {
      r = result;
      *stop = YES;
    };
  [self enumerateMatchesInString: string
			 options: opts
			   range: range
		      usingBlock: block];
  return r;
}

- (NSArray*) matchesInString: (NSString*)string
                     options:(NSMatchingOptions)opts
                       range:(NSRange)range
{
  NSMutableArray	*array = [NSMutableArray array];

  opts &= ~NSMatchingReportProgress;
  opts &= ~NSMatchingReportCompletion;

  GSRegexBlock block =
    ^(NSTextCheckingResult *result, NSMatchingFlags flags, BOOL *stop)
    {
      [array addObject: result];
    };
  [self enumerateMatchesInString: string
			 options: opts
			   range: range
		      usingBlock: block];
  return array;
}

- (NSRange) rangeOfFirstMatchInString: (NSString*)string
                              options: (NSMatchingOptions)opts
                                range: (NSRange)range
{
  __block NSRange r;

  opts &= ~NSMatchingReportProgress;
  opts &= ~NSMatchingReportCompletion;

  GSRegexBlock block =
    ^(NSTextCheckingResult *result, NSMatchingFlags flags, BOOL *stop)
    {
      r = [result range];
      *stop = YES;
    };
  [self enumerateMatchesInString: string
			 options: opts
			   range: range
		      usingBlock: block];
  return r;
}

#else
#	warning Your compiler does not support blocks.  NSRegularExpression will deviate from the documented behaviour when subclassing and any code that subclasses NSRegularExpression may break in unexpected ways.  It is strongly recommended that you use a compiler with blocks support.
#	ifdef __clang__
#		warning Your compiler would support blocks if you added -fblocks to your OBJCFLAGS
#	endif

#ifdef NSRegularExpressionWorks
#define FAKE_BLOCK_HACK(failRet, code) \
  UErrorCode s = 0;\
  UText txt = UTEXT_INITIALIZER;\
  BOOL stop = NO;\
  URegularExpression *r = setupRegex(regex, string, &txt, opts, range, 0);\
  if (NULL == r) { return failRet; }\
  if (opts & NSMatchingAnchored)\
    {\
      if (uregex_lookingAt(r, -1, &s) && (0==s))\
	{\
	  code\
	}\
    }\
  else\
    {\
      while (!stop && uregex_findNext(r, &s) && (s == 0))\
	{\
	  code\
	}\
    }\
  utext_close(&txt);\
  uregex_close(r);
#else
#define FAKE_BLOCK_HACK(failRet, code) \
  [NSException raise: NSInvalidArgumentException \
              format: @"NSRegularExpression requires ICU 4.4 or later"]
#endif

- (NSUInteger) numberOfMatchesInString: (NSString*)string
                               options: (NSMatchingOptions)opts
                                 range: (NSRange)range

{
  NSUInteger	count = 0;

  FAKE_BLOCK_HACK(count,
    {
      count++;
    });
  return count;
}

- (NSTextCheckingResult*) firstMatchInString: (NSString*)string
                                     options: (NSMatchingOptions)opts
                                       range: (NSRange)range
{
  NSTextCheckingResult	*result = nil;
  NSUInteger		groups = [self numberOfCaptureGroups] + 1;
  NSRange		ranges[groups];

  FAKE_BLOCK_HACK(result,
    {
      prepareResult(self, r, ranges, groups, &s);
      result = [NSTextCheckingResult
	regularExpressionCheckingResultWithRanges: ranges
					    count: groups
				regularExpression: self];
      stop = YES;
    });
  return result;
}

- (NSArray*) matchesInString: (NSString*)string
                     options: (NSMatchingOptions)opts
                       range: (NSRange)range
{
  NSMutableArray	*array = [NSMutableArray array];
  NSUInteger		groups = [self numberOfCaptureGroups] + 1;
  NSRange		ranges[groups];

  FAKE_BLOCK_HACK(array,
    {
      NSTextCheckingResult	*result = NULL;

      prepareResult(self, r, ranges, groups, &s);
      result = [NSTextCheckingResult
	regularExpressionCheckingResultWithRanges: ranges
					    count: groups
				regularExpression: self];
      [array addObject: result];
    });
  return array;
}

- (NSRange) rangeOfFirstMatchInString: (NSString*)string
                              options: (NSMatchingOptions)opts
                                range: (NSRange)range
{
  NSRange result = {0,0};

  FAKE_BLOCK_HACK(result,
    {
      prepareResult(self, r, &result, 1, &s);
      stop = YES;
    });
  return result;
}

#endif

- (NSUInteger) replaceMatchesInString: (NSMutableString*)string
                              options: (NSMatchingOptions)opts
                                range: (NSRange)range
                         withTemplate: (NSString*)template
{
  // FIXME: We're computing a value that is most likely ignored in an
  // expensive way.
  NSInteger	results = [self numberOfMatchesInString: string
						options: opts
						  range: range];
#ifdef NSRegularExpressionWorks
  UErrorCode	s = 0;
  UText		txt = UTEXT_INITIALIZER;
  UText		replacement = UTEXT_INITIALIZER;
  GSUTextString	*ret = [GSUTextString new];
  URegularExpression *r = setupRegex(regex, string, &txt, opts, range, 0);
  UText		*output = NULL;

  UTextInitWithNSString(&replacement, template);

  output = uregex_replaceAllUText(r, &replacement, NULL, &s);
  utext_clone(&ret->txt, output, TRUE, TRUE, &s);
  [string setString: ret];
  [ret release];
  uregex_close(r);

  utext_close(&txt);
  utext_close(output);
  utext_close(&replacement);
#endif
  return results;
}

- (NSString*) stringByReplacingMatchesInString: (NSString*)string
                                       options: (NSMatchingOptions)opts
                                         range: (NSRange)range
                                  withTemplate: (NSString*)template
{
#ifdef NSRegularExpressionWorks
  UErrorCode	s = 0;
  UText		txt = UTEXT_INITIALIZER;
  UText		replacement = UTEXT_INITIALIZER;
  UText		*output = NULL;
  GSUTextString	*ret = [GSUTextString new];
  URegularExpression *r = setupRegex(regex, string, &txt, opts, range, 0);

  UTextInitWithNSString(&replacement, template);

  output = uregex_replaceAllUText(r, &replacement, NULL, &s);
  utext_clone(&ret->txt, output, TRUE, TRUE, &s);
  uregex_close(r);

  utext_close(&txt);
  utext_close(output);
  utext_close(&replacement);
  return ret;
#else
  // FIXME
  return nil;
#endif
}

- (NSString*) replacementStringForResult: (NSTextCheckingResult*)result
                                inString: (NSString*)string
                                  offset: (NSInteger)offset
                                template: (NSString*)template
{
#ifdef NSRegularExpressionWorks
  UErrorCode	s = 0;
  UText		txt = UTEXT_INITIALIZER;
  UText		replacement = UTEXT_INITIALIZER;
  UText		*output = NULL;
  GSUTextString	*ret = [GSUTextString new];
  NSRange	range = [result range];
  URegularExpression *r = setupRegex(regex,
				     [string substringWithRange: range],
				     &txt,
				     0,
				     NSMakeRange(0, range.length),
				     0);

  UTextInitWithNSString(&replacement, template);

  output = uregex_replaceFirstUText(r, &replacement, NULL, &s);
  utext_clone(&ret->txt, output, TRUE, TRUE, &s);
  uregex_close(r);

  utext_close(&txt);
  utext_close(output);
  utext_close(&replacement);
  return ret;
#else
  //FIXME
  return nil;
#endif
}

- (NSRegularExpressionOptions) options
{
  return options;
}

- (NSUInteger) numberOfCaptureGroups
{
#ifdef NSRegularExpressionWorks
  UErrorCode s = 0;
  return uregex_groupCount(regex, &s);
#else
  // FIXME
  return 0;
#endif
}

- (void) dealloc
{
#ifdef NSRegularExpressionWorks
  uregex_close(regex);
#endif
  RELEASE(pattern);
  [super dealloc];
}

- (void) encodeWithCoder: (NSCoder*)aCoder
{
  if ([aCoder allowsKeyedCoding])
    {
      [aCoder encodeInteger: options forKey: @"options"];
      [aCoder encodeObject: [self pattern] forKey: @"pattern"];
    }
  else
    {
      [aCoder encodeValueOfObjCType: @encode(NSRegularExpressionOptions)
				 at: &options];
      [aCoder encodeObject: [self pattern]];
    }
}

- (id) initWithCoder: (NSCoder*)aCoder
{
  NSString *aPattern;
  NSRegularExpressionOptions opts;

  if ([aCoder allowsKeyedCoding])
    {
      opts = [aCoder decodeIntegerForKey: @"options"];
      aPattern = [aCoder decodeObjectForKey: @"pattern"];
    }
  else
    {
      [aCoder decodeValueOfObjCType: @encode(NSRegularExpressionOptions)
				 at: &opts];
      aPattern = [aCoder decodeObject];
    }
  return [self initWithPattern: aPattern options: opts error: NULL];
}

- (id) copyWithZone: (NSZone*)aZone
{
#ifdef NSRegularExpressionWorks
  NSRegularExpressionOptions	opts = options;
  UErrorCode			s = 0;
  URegularExpression		*r = uregex_clone(regex, &s);

  if (0 != s)
    {
      return nil;
    }

  self = [[self class] allocWithZone: aZone];
  if (nil == self)
    {
      return nil;
    }
  options = opts;
  regex = r;
  return self;
#else
  return [[[self class] allocWithZone: aZone] initWithPattern: [self pattern]
                                                      options: [self options]
                                                        error: NULL];
#endif
}
@end