//
//   Copyright 2014 Slack Technologies, Inc.
//
//   Licensed under the Apache License, Version 2.0 (the "License");
//   you may not use this file except in compliance with the License.
//   You may obtain a copy of the License at
//
//       http://www.apache.org/licenses/LICENSE-2.0
//
//   Unless required by applicable law or agreed to in writing, software
//   distributed under the License is distributed on an "AS IS" BASIS,
//   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//   See the License for the specific language governing permissions and
//   limitations under the License.
//

#import "SLKTextView+SLKAdditions.h"

@implementation SLKTextView (SLKAdditions)

- (void)slk_clearText:(BOOL)clearUndo
{
    // Important to call self implementation, as SLKTextView overrides setText: to add additional features.
    [self setText:nil];
    
    if (self.undoManagerEnabled && clearUndo) {
        [self.undoManager removeAllActions];
    }
}

- (void)slk_scrollToCaretPositonAnimated:(BOOL)animated
{
    if (animated) {
        [self scrollRangeToVisible:self.selectedRange];
    }
    else {
        [UIView performWithoutAnimation:^{
            [self scrollRangeToVisible:self.selectedRange];
        }];
    }
}

- (void)slk_scrollToBottomAnimated:(BOOL)animated
{
    CGRect rect = [self caretRectForPosition:self.selectedTextRange.end];
    rect.size.height += self.textContainerInset.bottom;
    
    if (animated) {
        [self scrollRectToVisible:rect animated:animated];
    }
    else {
        [UIView performWithoutAnimation:^{
            [self scrollRectToVisible:rect animated:NO];
        }];
    }
}

- (void)slk_insertNewLineBreak
{
    [self slk_insertTextAtCaretRange:@"\n"];
    
    // if the text view cannot expand anymore, scrolling to bottom are not animated to fix a UITextView issue scrolling twice.
    BOOL animated = !self.isExpanding;
    
    //Detected break. Should scroll to bottom if needed.
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.0125 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        [self slk_scrollToBottomAnimated:animated];
    });
}

- (void)slk_insertTextAtCaretRange:(NSString *)text
{
    NSRange range = [self slk_insertText:text inRange:self.selectedRange];
    self.selectedRange = NSMakeRange(range.location, 0);
}

- (NSRange)slk_insertText:(NSString *)text inRange:(NSRange)range
{
    // Skip if the text is empty
    if (text.length == 0) {
        return NSMakeRange(0, 0);
    }
    
    // Registers for undo management
    [self slk_prepareForUndo:@"Text appending"];
    
    // Append the new string at the caret position
    if (range.length == 0)
    {
        NSString *leftString = [self.text substringToIndex:range.location];
        NSString *rightString = [self.text substringFromIndex: range.location];
        
        self.text = [NSString stringWithFormat:@"%@%@%@", leftString, text, rightString];
        
        range.location += [text length];
        return range;
    }
    // Some text is selected, so we replace it with the new text
    else if (range.location != NSNotFound && range.length > 0)
    {
        self.text = [self.text stringByReplacingCharactersInRange:range withString:text];
        
        return NSMakeRange(range.location+[self.text rangeOfString:text].length, text.length);
    }
    
    // No text has been inserted, but still return the caret range
    return self.selectedRange;
}

- (NSString *)slk_wordAtCaretRange:(NSRangePointer)range
{
    return [self slk_wordAtRange:self.selectedRange rangeInText:range];
}

- (NSString *)slk_wordAtRange:(NSRange)range rangeInText:(NSRangePointer)rangePointer
{
    NSString *text = self.text;
    NSInteger location = range.location;
    
    // Aborts in case minimum requieres are not fufilled
    if (text.length == 0 || location < 0 || (range.location+range.length) > text.length) {
        *rangePointer = NSMakeRange(0, 0);
        return nil;
    }
    
    NSString *leftPortion = [text substringToIndex:location];
    NSArray *leftComponents = [leftPortion componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
    NSString *leftWordPart = [leftComponents lastObject];
    
    NSString *rightPortion = [text substringFromIndex:location];
    NSArray *rightComponents = [rightPortion componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
    NSString *rightPart = [rightComponents firstObject];
    
    if (location > 0) {
        NSString *characterBeforeCursor = [text substringWithRange:NSMakeRange(location-1, 1)];
        
        if ([characterBeforeCursor isEqualToString:@" "]) {
            // At the start of a word, just use the word behind the cursor for the current word
            *rangePointer = NSMakeRange(location, rightPart.length);
            
            return rightPart;
        }
    }
    
    // In the middle of a word, so combine the part of the word before the cursor, and after the cursor to get the current word
    *rangePointer = NSMakeRange(location-leftWordPart.length, leftWordPart.length+rightPart.length);
    NSString *word = [leftWordPart stringByAppendingString:rightPart];
    
    // If a break is detected, return the last component of the string
    if ([word rangeOfString:@"\n"].location != NSNotFound) {
        *rangePointer = [text rangeOfString:word];
        word = [[word componentsSeparatedByString:@"\n"] lastObject];
    }

    return word;
}

- (void)slk_prepareForUndo:(NSString *)description
{
    if (!self.undoManagerEnabled) {
        return;
    }
    
	SLKTextView *prepareInvocation = [self.undoManager prepareWithInvocationTarget:self];
	[prepareInvocation setText:self.text];
	[self.undoManager setActionName:description];
	
}

@end