/*
	NDKeyboardLayout.m

	Created by Nathan Day on 01.18.10 under a MIT-style license. 
	Copyright (c) 2010 Nathan Day

	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.

	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	THE SOFTWARE.
 */

#import "NDKeyboardLayout.h"
#include <libkern/OSAtomic.h>

NSString		* const NDKeyboardLayoutSelectedKeyboardInputSourceChangedNotification = @"NDKeyboardLayoutSelectedKeyboardInputSourceChanged";
NSString		* const NDKeyboardLayoutPreviousKeyboardLayoutUserInfoKey = @"NDKeyboardLayoutPreviousKeyboardLayout";

struct ReverseMappingEntry
{
	UniChar		character;
	BOOL		keypad;
	UInt16		keyCode;
};

struct UnmappedEntry
{
	UniChar		character;
	UInt16		keyCode;
	unichar		description[4];
};

struct UnmappedEntry	unmappedKeys[] =
{
	{NSDeleteFunctionKey, 0x33, {0x232B,'\0','\0','\0'}},
	{NSF17FunctionKey, 0x40, {'F','1','7','\0'}},
	{NSClearDisplayFunctionKey, 0x47, {0x2327,'\0','\0','\0'}},
	{NSF18FunctionKey, 0x4F, {'F','1','8','\0'}},
	{NSF19FunctionKey, 0x50, {'F','1','9','\0'}},
	{NSF5FunctionKey, 0x60, {'F','5','\0','\0'}},
	{NSF6FunctionKey, 0x61, {'F','6','\0','\0'}},
	{NSF7FunctionKey, 0x62, {'F','7','\0','\0'}},
	{NSF3FunctionKey, 0x63, {'F','3','\0','\0'}},
	{NSF8FunctionKey, 0x64, {'F','8','\0','\0'}},
	{NSF9FunctionKey, 0x65, {'F','9','\0','\0'}},
	{NSF11FunctionKey, 0x67, {'F','1','1','\0'}},
	{NSF14FunctionKey, 0x68, {'F','1','4','\0'}},
	{NSF13FunctionKey, 0x69, {'F','1','3','\0'}},
	{NSF16FunctionKey, 0x6A, {'F','1','6','\0'}},
	{NSF10FunctionKey, 0x6D, {'F','1','0','\0'}},
	{NSF12FunctionKey, 0x6F, {'F','1','2','\0'}},
	{NSF15FunctionKey, 0x71, {'F','1','5','\0'}},
	{NSHomeFunctionKey, 0x73, {0x21F1,'\0','\0','\0'}},
	{NSPageUpFunctionKey, 0x74, {0x21DE,'\0','\0','\0'}},
	{NSDeleteCharFunctionKey, 0x75, {0x2326,'\0','\0','\0'}},
	{NSF4FunctionKey, 0x76, {'F','4','\0','\0'}},
	{NSEndFunctionKey, 0x77, {0x21F2,'\0','\0','\0'}},
	{NSF2FunctionKey, 0x78, {'F','2','\0','\0'}},
	{NSPageDownFunctionKey, 0x79, {0x21DF,'\0','\0','\0'}},
	{NSF1FunctionKey, 0x7A, {'F','1','\0','\0'}},
	{NSLeftArrowFunctionKey, 0x7B, {0x2190,'\0','\0','\0'}},
	{NSRightArrowFunctionKey, 0x7C, {0x2192,'\0','\0','\0'}},
	{NSDownArrowFunctionKey, 0x7D, {0x2193,'\0','\0','\0'}},
	{NSUpArrowFunctionKey, 0x7E, {0x2191,'\0','\0','\0'}}
//	{NSF20FunctionKey, 0xXXXX},
//	{NSF21FunctionKey, 0xXXXX},
//	{NSF22FunctionKey, 0xXXXX},
//	{NSF23FunctionKey, 0xXXXX},
//	{NSF24FunctionKey, 0xXXXX},
//	{NSF25FunctionKey, 0xXXXX},
//	{NSF26FunctionKey, 0xXXXX},
//	{NSF27FunctionKey, 0xXXXX},
//	{NSF28FunctionKey, 0xXXXX},
//	{NSF29FunctionKey, 0xXXXX},
//	{NSF30FunctionKey, 0xXXXX},
//	{NSF31FunctionKey, 0xXXXX},
//	{NSF32FunctionKey, 0xXXXX},
//	{NSF33FunctionKey, 0xXXXX},
//	{NSF34FunctionKey, 0xXXXX},
//	{NSF35FunctionKey, 0xXXXX},
//	{NSInsertFunctionKey, 0xXXXX},
//	{NSBeginFunctionKey, 0xXXXX},
//	{NSPrintScreenFunctionKey, 0xXXXX},
//	{NSScrollLockFunctionKey, 0xXXXX},
//	{NSPauseFunctionKey, 0xXXXX},
//	{NSSysReqFunctionKey, 0xXXXX},
//	{NSBreakFunctionKey, 0xXXXX},
//	{NSResetFunctionKey, 0xXXXX},
//	{NSStopFunctionKey, 0xXXXX},
//	{NSMenuFunctionKey, 0xXXXX},
//	{NSUserFunctionKey, 0xXXXX},
//	{NSSystemFunctionKey, 0xXXXX},
//	{NSPrintFunctionKey, 0xXXXX},
//	{NSClearLineFunctionKey, 0xXXXX},
//	{NSInsertLineFunctionKey, 0xXXXX},
//	{NSDeleteLineFunctionKey, 0xXXXX},
//	{NSInsertCharFunctionKey, 0xXXXX},
//	{NSPrevFunctionKey, 0xXXXX},
//	{NSNextFunctionKey, 0xXXXX},
//	{NSSelectFunctionKey, 0xXXXX},
//	{NSExecuteFunctionKey, 0xXXXX},
//	{NSUndoFunctionKey, 0xXXXX},
//	{NSRedoFunctionKey, 0xXXXX},
//	{NSFindFunctionKey, 0xXXXX},
//	{NSHelpFunctionKey, 0xXXXX},
//	{NSModeSwitchFunctionKey, 0xXXXX}
};

@interface NDKeyboardLayout ()

@property(readonly,nonatomic)	const UCKeyboardLayout		* keyboardLayoutPtr;

@end

static int _reverseMappingEntryCmpFunc( const void * a, const void * b )
{
	struct ReverseMappingEntry		* theA = (struct ReverseMappingEntry*)a,
									* theB = (struct ReverseMappingEntry*)b;
	return theA->character != theB->character ? theA->character - theB->character : theA->keypad - theB->keypad;
}

static struct ReverseMappingEntry * _searchreverseMapping( struct ReverseMappingEntry * aMapping, NSUInteger aLength, struct ReverseMappingEntry * aSearchValue )
{
    NSInteger	low = 0,
				high = aLength - 1,
				mid,
				result;
    
    while( low <= high )
	{
        mid = (low + high)>>1;
        result = _reverseMappingEntryCmpFunc( &aMapping[mid], aSearchValue );
        if( result > 0 )
            high = mid - 1;
        else if( result < 0 )
            low = mid + 1;
        else
            return &aMapping[mid];
    }
    return NULL;
}

static struct UnmappedEntry * _unmappedEntryForKeyCode( UInt16 aKeyCode )
{
    NSInteger	low = 0,
				high = sizeof(unmappedKeys)/sizeof(*unmappedKeys) - 1,
				mid,
				result;
    
    while( low <= high )
	{
        mid = (low + high)>>1;
        result = unmappedKeys[mid].keyCode - aKeyCode;
        if( result > 0 )
            high = mid - 1;
        else if( result < 0 )
            low = mid + 1;
        else
            return &unmappedKeys[mid];
    }
    return '\0';
}

static const size_t			kBufferSize = 4;
static NSUInteger _characterForModifierFlags( unichar aBuff[kBufferSize], UInt32 aModifierFlags )
{
	NSUInteger		thePos = 0;
	memset( aBuff, 0, kBufferSize );
	if(aModifierFlags & NSEventModifierFlagControl)
		aBuff[thePos++] = kControlUnicode;
	
	if(aModifierFlags & NSEventModifierFlagOption)
		aBuff[thePos++] = kOptionUnicode;
	
	if(aModifierFlags & NSEventModifierFlagShift)
		aBuff[thePos++] = kShiftUnicode;
	
	if(aModifierFlags & NSEventModifierFlagCommand)
		aBuff[thePos++] = kCommandUnicode;
	return thePos;
}

/*
 * NDCocoaModifierFlagsForCarbonModifierFlags()
 */
NSUInteger NDCocoaModifierFlagsForCarbonModifierFlags( NSUInteger aModifierFlags )
{
	NSUInteger	theCocoaModifierFlags = 0;
	
	if(aModifierFlags & shiftKey)
		theCocoaModifierFlags |= NSEventModifierFlagShift;
	
	if(aModifierFlags & controlKey)
		theCocoaModifierFlags |= NSEventModifierFlagControl;
	
	if(aModifierFlags & optionKey)
		theCocoaModifierFlags |= NSEventModifierFlagOption;
	
	if(aModifierFlags & cmdKey)
		theCocoaModifierFlags |= NSEventModifierFlagCommand;
	
	return theCocoaModifierFlags;
}

/*
 * NDCarbonModifierFlagsForCocoaModifierFlags()
 */
NSUInteger NDCarbonModifierFlagsForCocoaModifierFlags( NSUInteger aModifierFlags )
{
	NSUInteger	theCarbonModifierFlags = 0;
	
	if(aModifierFlags & NSShiftKeyMask)
		theCarbonModifierFlags |= shiftKey;
	
	if(aModifierFlags & NSControlKeyMask)
		theCarbonModifierFlags |= controlKey;
	
	if(aModifierFlags & NSAlternateKeyMask)
		theCarbonModifierFlags |= optionKey;
	
	if(aModifierFlags & NSCommandKeyMask)
		theCarbonModifierFlags |= cmdKey;
	
	return theCarbonModifierFlags;
}

@implementation NDKeyboardLayout

#pragma mark Utility Methods

- (void)generateMappings
{
	mappings = (struct ReverseMappingEntry*)calloc( 128 + sizeof(unmappedKeys)/sizeof(*unmappedKeys), sizeof(struct ReverseMappingEntry) );

	numberOfMappings = 0;
	
	for( NSUInteger i = 0; i < 128; i++ )
	{
		UInt32			theDeadKeyState = 0;
		UniCharCount	theLength = 0;

		if( UCKeyTranslate( self.keyboardLayoutPtr,
							   i,
							   kUCKeyActionDisplay,
							   0,
							   LMGetKbdType(),
							   kUCKeyTranslateNoDeadKeysBit,
							   &theDeadKeyState,
							   1,
							   &theLength,
							   &mappings[numberOfMappings].character ) == noErr && theLength > 0 && isprint(mappings[numberOfMappings].character) )
		{
			mappings[numberOfMappings].keyCode = i;
			numberOfMappings++;
		}
	}
	
	/*	add unmapped keys	*/
	for( NSUInteger i = 0; i < sizeof(unmappedKeys)/sizeof(*unmappedKeys); i++ )
	{
		mappings[numberOfMappings].character = unmappedKeys[i].character;
		mappings[numberOfMappings].keyCode = unmappedKeys[i].keyCode;
		numberOfMappings++;
	}
	
	mappings = (struct ReverseMappingEntry*)realloc( (void*)mappings, numberOfMappings*sizeof(struct ReverseMappingEntry) );

	// sort so we can perform binary searches
	qsort( (void *)mappings, numberOfMappings, sizeof(struct ReverseMappingEntry), _reverseMappingEntryCmpFunc );

	/* find keypad keys and set the keypad flag	*/
	for( NSUInteger i = 1; i < numberOfMappings; i++ )
	{
		NSParameterAssert( mappings[i-1].keyCode != mappings[i].keyCode );
		if( mappings[i-1].character == mappings[i].character )	// assume large keycode is a keypad
		{
			if( mappings[i-1].keyCode > mappings[i].keyCode )		// make the keypad entry is second
			{
				UInt16		theTemp = mappings[i-1].keyCode;
				mappings[i-1].keyCode = mappings[i].keyCode;
				mappings[i].keyCode = theTemp;
			}
			mappings[i].keypad = YES;
		}
	}

#ifdef DEBUGGING_CODE
	for( NSUInteger i = 1; i < numberOfMappings; i++ )
	{
		fprintf( stderr, "%d -> %c[%d]%s\n",
				mappings[i].keyCode,
				(char)mappings[i].character,
				mappings[i].character,
				mappings[i].keypad ? " keypad" : ""
				);
		NSAssert3( mappings[i-1].character <= mappings[i].character, @"[%d] %d <= %d", i, mappings[i-1].character, mappings[i].character );
	}
#endif
}

#pragma mark Constructor Methods

static volatile NDKeyboardLayout		* kCurrentKeyboardLayout = nil;

static void NDKeyboardLayoutNotificationCallback( CFNotificationCenterRef aCenter, void * self, CFStringRef aName, const void * anObj, CFDictionaryRef aUserInfo )
{
	NSDictionary		* theUserInfo = [NSDictionary dictionaryWithObject:kCurrentKeyboardLayout forKey:NDKeyboardLayoutPreviousKeyboardLayoutUserInfoKey];
	@synchronized(self) { kCurrentKeyboardLayout = nil; }
	[[NSNotificationCenter defaultCenter] postNotificationName:NDKeyboardLayoutSelectedKeyboardInputSourceChangedNotification object:(__bridge id _Nullable)(self) userInfo:theUserInfo];
}

+ (void)initialize
{
	CFNotificationCenterAddObserver( CFNotificationCenterGetLocalCenter(),
									(const void *)self,
									NDKeyboardLayoutNotificationCallback,
									kTISNotifySelectedKeyboardInputSourceChanged,
									NULL,
									CFNotificationSuspensionBehaviorDeliverImmediately
									);
}

+ (id)keyboardLayout
{
	if( kCurrentKeyboardLayout == nil )
	{
		@synchronized(self)
		{	/*
				Try different method until we succeed.
			 */
			TISInputSourceRef (*theInputSourceFunctions[])() = {
									TISCopyInputMethodKeyboardLayoutOverride,
									TISCopyCurrentKeyboardLayoutInputSource,
									TISCopyCurrentASCIICapableKeyboardLayoutInputSource
								};

			for( NSUInteger i = 0; i < sizeof(theInputSourceFunctions)/sizeof(*theInputSourceFunctions) && kCurrentKeyboardLayout == nil; i++ )
			{
				TISInputSourceRef		theInputSource = theInputSourceFunctions[i]();
				if( theInputSource != NULL )
				{
					kCurrentKeyboardLayout = [[self alloc] initWithInputSource:theInputSource];
					CFRelease(theInputSource);
				}
			}
		}
	}

	return kCurrentKeyboardLayout;
}

- (id)init
{
	return [NDKeyboardLayout keyboardLayout];
}

- (id)initWithLanguage:(NSString *)aLangauge { return [self initWithInputSource:TISCopyInputSourceForLanguage((__bridge CFStringRef)aLangauge)]; }

- (id)initWithInputSource:(TISInputSourceRef)aSource
{
	if( (self = [super init]) != nil )
	{
		if( aSource != NULL && (keyboardLayoutData = (CFDataRef)TISGetInputSourceProperty(aSource, kTISPropertyUnicodeKeyLayoutData)) != nil )
		{
			CFRetain( keyboardLayoutData );
		}
		else
			self = nil;
	}
	return self;
}

- (void)dealloc
{
	if( mappings != NULL )
		free( (void*)mappings );
	if( keyboardLayoutData != NULL )
		CFRelease( keyboardLayoutData );
}

- (NSString*)stringForCharacter:(unichar)aCharacter modifierFlags:(UInt32)aModifierFlags
{
	return [self stringForKeyCode:[self keyCodeForCharacter:aCharacter numericPad:(aModifierFlags&NSNumericPadKeyMask) != 0] modifierFlags:aModifierFlags];
}

- (NSString*)stringForKeyCode:(UInt16)aKeyCode modifierFlags:(UInt32)aModifierFlags
{
	NSString				* theResult = nil;
	struct UnmappedEntry	* theEntry = _unmappedEntryForKeyCode( aKeyCode );		// is it one of the unmapped values
	
	if( theEntry != NULL )
	{
		unichar		theCharacter[sizeof(theEntry->description)/sizeof(*theEntry->description)+4+1];
		memset( theCharacter, 0, sizeof(theCharacter) );
		NSUInteger	thePos = _characterForModifierFlags(theCharacter,aModifierFlags);
		memcpy( theCharacter+thePos, theEntry->description, sizeof(theEntry->description) );
		theResult = [NSString stringWithCharacters:theCharacter length:sizeof(theEntry->description)/sizeof(*theEntry->description)+thePos];
	}
	else
	{
		UInt32			theDeadKeyState = 0;
		UniCharCount	theLength = 0;
		UniChar			theCharacter[260];

		NSUInteger		thePos = _characterForModifierFlags(theCharacter,aModifierFlags);

		if( UCKeyTranslate( self.keyboardLayoutPtr, aKeyCode,
							 kUCKeyActionDisplay,
							 (UInt32)NDCarbonModifierFlagsForCocoaModifierFlags(aModifierFlags),
							 LMGetKbdType(),
							 kUCKeyTranslateNoDeadKeysBit,
							 &theDeadKeyState,
							 sizeof(theCharacter)/sizeof(*theCharacter)-thePos,
							 &theLength,
							 theCharacter+thePos ) == noErr )
		{

			theResult = [[NSString stringWithCharacters:theCharacter length:theLength+thePos] uppercaseString];
		}
	}
	return theResult;
}

- (unichar)characterForKeyCode:(UInt16)aKeyCode
{
	unichar					theChar = 0;
	struct UnmappedEntry *	theEntry = _unmappedEntryForKeyCode( aKeyCode );

	if( theEntry == NULL )					// is it one of the unmapped values
	{
		UInt32			theDeadKeyState = 0;
		UniCharCount	theLength = 0;
		UniChar			theCharacter[256];
		
		if( UCKeyTranslate( self.keyboardLayoutPtr, aKeyCode,
						   kUCKeyActionDisplay,
						   0,
						   LMGetKbdType(),
						   kUCKeyTranslateNoDeadKeysBit,
						   &theDeadKeyState,
						   sizeof(theCharacter)/sizeof(*theCharacter),
						   &theLength,
						   theCharacter ) == noErr )
		{
			theChar = theCharacter[0];
		}
	}
	else
		theChar  = theEntry->character;
	return toupper(theChar);
}

- (UInt16)keyCodeForCharacter:(unichar)aCharacter { return [self keyCodeForCharacter:aCharacter numericPad:NO]; }

- (UInt16)keyCodeForCharacter:(unichar)aCharacter numericPad:(BOOL)aNumericPad
{
	struct ReverseMappingEntry	theSearchValue = { tolower(aCharacter), aNumericPad, 0 };
	struct ReverseMappingEntry	* theEntry = NULL;
	if( mappings == NULL )
		[self generateMappings];
	theEntry = _searchreverseMapping( mappings, numberOfMappings, &theSearchValue );
	return theEntry ? theEntry->keyCode : '\0';
}

#pragma mark - private

- (const UCKeyboardLayout *)keyboardLayoutPtr { return (const UCKeyboardLayout *)CFDataGetBytePtr(keyboardLayoutData); }

@end