FABarChartDrawLayer.m

//
//  FAMBarChartDrawLayer.m
//  frank-ios
//
//  Created by Ринат Муртазин on 08/12/15.
//  Copyright © 2015 Frank. All rights reserved.
//

#import "FABarChartDrawLayer.h"
#import "FAMBarChartValues.h"
#import "FAMBarChartValue.h"
#import "FABarChartView.h"
#import "FAUIHelper.h"
#import <CoreText/CoreText.h>
#import "RSTimingFunction.h"

#define MAX_BAR_HEIGHT 65.f
#define BAR_CORNER_RADIUS 2.f
#define DEFAULT_SIDE_PADDING 14.f

#define BARS_Y_ANIMATION_SHIFT 10.f
#define LEGEND_Y_ANIMATION_SHIFT 15.f
#define BAR_AND_LEGEND_ANIMATION_DURATION 1.f

@implementation FABarChartDrawLayer
{
    CGFloat _barWidth;
    CGFloat _legendWidth;
    CGFloat _gap;
    CGFloat _minBarHeight;
    CGFloat _startX;
    
    UIColor *_legendColor;
    NSArray *_incomeColors;
    NSArray *_expenseColors;
    
    BOOL _drawLabelInCenter;
    BOOL _drawLabelHalfWidth;
    BOOL _drawLabelMonthLegend;
    
    RSTimingFunction *_timingFunction;
    
    CGFloat _delayBarAnimation;
    CGFloat _delayLegendAnimation;
    
    __weak FABarChartView *_barChartView;
}

#pragma mark - Init

- (instancetype)initWithBarView:(FABarChartView *)barChartView
{
    self = [super init];
    
    if(self)
    {
        _barChartView = barChartView;
        
        _gap = [FAUIHelper pixelsToPoints:4];
        
        _minBarHeight = [FAUIHelper pixelsToPoints:8];
        
        _legendColor = [UIColor colorFromHex:@"647178"];
        
        // 0: zero value color
        // 4: last bar color
   
        // TODO: ВЫНЕСТИ ЭТО В СТИЛЕВОЙ КОМПОНЕНТ!!
        _incomeColors = @[
                          [UIColor colorFromHex:@"166844"],
                          [UIColor colorFromHex:@"02a25c"],
                          [UIColor colorFromHex:@"17c868"],
                          [UIColor colorFromHex:@"27d35d"],
                          [UIColor colorFromHex:@"1ddb44"]
                          ];
        
        _expenseColors = @[
                           [UIColor colorFromHex:@"4c656f"],
                           [UIColor colorFromHex:@"5f6e75"],
                           [UIColor colorFromHex:@"717d82"],
                           [UIColor colorFromHex:@"8c9599"],
                           [UIColor colorFromHex:@"a7aeb1"]
                           ];
        
        self.contentsScale = [UIScreen mainScreen].scale;
        
        _timingFunction = [RSTimingFunction timingFunctionWithControlPoint1:CGPointMake(0.f, 0.6f)
                                                              controlPoint2:CGPointMake(0.2f, 1.f)];
    }
    
    return self;
}

- (instancetype)initWithLayer:(FABarChartDrawLayer *)layer
{
    self = [super initWithLayer:layer];
    
    if(self)
    {
        _barWidth = layer->_barWidth;
        _legendWidth = layer->_legendWidth;
        _gap = layer->_gap;
        _minBarHeight = layer->_minBarHeight;
        _startX = layer->_startX;
        
        _legendColor = layer->_legendColor;
        _incomeColors = layer->_incomeColors;
        _expenseColors = layer->_expenseColors;
        
        _drawLabelInCenter = layer->_drawLabelInCenter;
        _drawLabelHalfWidth = layer->_drawLabelHalfWidth;
        _drawLabelMonthLegend = layer->_drawLabelMonthLegend;
        
        _barChartView = layer->_barChartView;
        
        self.contentsScale = layer.contentsScale;
        
        _timingFunction = layer->_timingFunction;
        
        _delayBarAnimation = layer->_delayBarAnimation;
        _delayLegendAnimation = layer->_delayLegendAnimation;
    }
    
    return self;
}

- (void)calculateOptions
{
    NSInteger count = [_barChartView.values.values count];
    
    CGFloat width = self.frame.size.width;
    
    CGFloat scale = [UIScreen mainScreen].scale;
    CGFloat barWidthPixels = width * scale - 2 * DEFAULT_SIDE_PADDING * scale;
    barWidthPixels += _gap * scale;
    barWidthPixels /= count;
    barWidthPixels -= _gap * scale;
    _barWidth = [FAUIHelper pixelsToPoints:barWidthPixels];
    
    _startX = width - (_barWidth + _gap) * count;
    _startX += _gap;
    _startX /= 2;
    _startX = [FAUIHelper roundToResolution:_startX];
    
    _delayBarAnimation = (_appearAnimationDuration - BAR_AND_LEGEND_ANIMATION_DURATION) / (float)(count - 1);
    
    
    // options for legend
    
    _legendWidth = width - 2 * _startX;
    _legendWidth /= [[_barChartView.values legendList] count];
    _legendWidth = [FAUIHelper roundToResolution:_legendWidth];
    
    _delayLegendAnimation = (_appearAnimationDuration - BAR_AND_LEGEND_ANIMATION_DURATION);
    _delayLegendAnimation /= (float)([[_barChartView.values legendList] count] - 1);
    
    EBarChartValueInterval interval = _barChartView.values.persistentIntervalValue;
    
    if(interval == EBarChartValueIntervalWeek)
    {
        _drawLabelHalfWidth = NO;
        _drawLabelInCenter = YES;
    }
    else if (interval == EBarChartValueIntervalTwoWeeks
             || interval == EBarChartValueIntervalYear
             || interval == EBarChartValueIntervalTwelveMonths)
    {
        _drawLabelHalfWidth = YES;
        _drawLabelInCenter = YES;
    }
    else if (interval == EBarChartValueIntervalMonth)
    {
        _drawLabelHalfWidth = NO;
        _drawLabelInCenter = YES;
        
        _drawLabelMonthLegend = YES;
        
        barWidthPixels = width * scale - 2 * DEFAULT_SIDE_PADDING * scale;
        barWidthPixels += _gap * scale;
        barWidthPixels /= 31;   // harcode fior month
        barWidthPixels -= _gap * scale;
        
        _legendWidth = 5 * ([FAUIHelper pixelsToPoints:floorf(barWidthPixels)] + _gap);
    }
    else if (interval == EBarChartValueIntervalThreeMonths
             || interval == EBarChartValueIntervalSixMonths
             || interval == EBarChartValueIntervalTwoYears
             || interval == EBarChartValueIntervalFiveYears)
    {
        _drawLabelHalfWidth = NO;
        _drawLabelInCenter = NO;
    }
}

#pragma mark - Overwritten

+ (BOOL)needsDisplayForKey:(NSString *)key
{
    if([key isEqualToString:@"appearAnimationDuration"])
    {
        return YES;
    }
    
    return  [super needsDisplayForKey:key];
}

#pragma mark Drawing

- (void)drawInContext:(CGContextRef)context
{
    if(self.modelLayer == self)
    {
        [self calculateOptions];
    }
    
    CGContextSetLineWidth(context, 2 * PIXEL);
    
    CGFloat x = _startX;
    
    CGFloat height = 0;
    
    NSInteger count = [_barChartView.values.values count];
    
    for(int i = 0; i < count; i++)
    {
        FAMBarChartValue *value = [_barChartView.values.values objectAtIndex:i];
        
        CGFloat animationValue = [self animValueForBar:i];
        
        CGContextSetFillColorWithColor(context, [[self colorForValue:value] colorWithAlphaComponent:animationValue].CGColor);
        
        height = MAX_BAR_HEIGHT * value.valueValue * animationValue;
        
        height = MAX(height, _minBarHeight);
        
        if(self.modelLayer == self)
        {
            height = [FAUIHelper roundToResolution:height];
        }
        
        CGFloat y = MAX_BAR_HEIGHT - height + BARS_Y_ANIMATION_SHIFT * (1 - animationValue);
        
        // get our rounded rect as a path
        UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(
                                                                                x,
                                                                                y,
                                                                                _barWidth,
                                                                                height
                                                                                )
                                                        cornerRadius:BAR_CORNER_RADIUS];
        
        
        // draw the path
        CGContextAddPath(context, path.CGPath);
        CGContextDrawPath(context, kCGPathFill);
        
        
        
        // stroke
        if(value.colorLevelValue > 0)
        {
            UIBezierPath *strokePath = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(
                                                                                          x + PIXEL,
                                                                                          y + PIXEL,
                                                                                          _barWidth - 2*PIXEL,
                                                                                          height - 2*PIXEL
                                                                                          )
                                                                  cornerRadius:BAR_CORNER_RADIUS];
            
            
            CGContextAddPath(context, strokePath.CGPath);
            CGContextSetStrokeColorWithColor(context, [[UIColor blackColor] colorWithAlphaComponent:animationValue * 0.11f].CGColor);
            CGContextDrawPath(context, kCGPathStroke);
        }
        
        x += _barWidth + _gap;
    }
    
    
    [self drawLegend:context];
}

- (void)drawLegend:(CGContextRef)context
{
    // flip the coordinate system
    CGContextSetTextMatrix(context, CGAffineTransformIdentity);
    CGContextTranslateCTM(context, 0, self.bounds.size.height);
    CGContextScaleCTM(context, 1.0, -1.0);
    
    CGContextSetShouldSmoothFonts(context, YES);
    CGContextSetShouldAntialias(context, YES);
    
    CGFloat legendHeight = self.frame.size.height - MAX_BAR_HEIGHT;
    CGFloat legendY = -6.f;
    CGFloat legendWidth = _drawLabelHalfWidth ? [FAUIHelper roundToResolution:_legendWidth / 2.f] : _legendWidth ;
    
    CGFloat x = _startX;
    
    // exception for month
    if(_drawLabelMonthLegend)
    {
        x -= [FAUIHelper roundToResolution:_legendWidth * 2 / 5.f];
    }
    
    if(_drawLabelInCenter == NO)
    {
        x += _gap;
    }
    else
    {
        x -= [FAUIHelper roundToResolution:_gap / 2.f];
    }
    
    NSMutableParagraphStyle *paragraphStyle = [NSMutableParagraphStyle new];
    paragraphStyle.alignment = _drawLabelInCenter ? NSTextAlignmentCenter : NSTextAlignmentLeft;
    
    
    NSMutableDictionary *attributes = @{
                                        NSForegroundColorAttributeName : _legendColor,
                                        NSFontAttributeName : [UIFont fontWithSize:10.f],
                                        NSParagraphStyleAttributeName : paragraphStyle
                                        }.mutableCopy;
    
    
    NSArray *legendList = [_barChartView.values legendList];
    
    for(int i = 0; i < [legendList count]; i++)
    {
        CGFloat animationValue = [self animValueForLegend:i];
        
        if(animationValue < 1)
        {
            [attributes setObject:[_legendColor colorWithAlphaComponent:animationValue]
                           forKey:NSForegroundColorAttributeName];
        }
        
        NSAttributedString *text = [[NSAttributedString alloc] initWithString:legendList[i]
                                                                   attributes:attributes];
        
        CGRect rect  = CGRectMake(x,
                                  legendY - LEGEND_Y_ANIMATION_SHIFT * (1.f - animationValue),
                                  legendWidth,
                                  legendHeight);
        
        if(self.modelLayer != self)
        {
            CGFloat nextPixel = ABS(rect.origin.y - [FAUIHelper roundToResolution:rect.origin.y]);
            
            NSMutableDictionary *tempAttributtes = [NSMutableDictionary dictionaryWithDictionary:attributes];
            
            [tempAttributtes setObject:[_legendColor colorWithAlphaComponent:animationValue * (0.3f * nextPixel / PIXEL)]
                                forKey:NSForegroundColorAttributeName];
            
            CGRect tempRect = rect;
            
            tempRect.origin.y = [FAUIHelper roundToResolution:tempRect.origin.y + PIXEL];
            
            
            [self drawText:[[NSAttributedString alloc] initWithString:legendList[i]
                                                           attributes:tempAttributtes]
                       ctx:context
                     frame:tempRect];
        }
        
        [self drawText:text
                   ctx:context
                 frame:[FAUIHelper roundFrameToResolution:rect]];
        
        x += _legendWidth;
        
        // exception for month
        
        if(_drawLabelMonthLegend
           && i == 0)
        {
            x -= [FAUIHelper roundToResolution:_legendWidth / 5.f];
        }
    }
}

- (void)drawText:(NSAttributedString *)text
             ctx:(CGContextRef)ctx
           frame:(CGRect)rect
{
    CGMutablePathRef path = CGPathCreateMutable();
    CGPathAddRect(path, NULL, rect);
    
    CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)text);
    CTFrameRef frame = CTFramesetterCreateFrame(framesetter, CFRangeMake(0, [text length]), path, NULL);
    
    CTFrameDraw(frame, ctx);
    
    CFRelease(frame);
    CFRelease(path);
    CFRelease(framesetter);
}

- (UIColor *)colorForValue:(FAMBarChartValue *)value
{
    NSArray *colors = value.isIncomeValue ? _incomeColors : _expenseColors ;
    
    return colors[value.colorLevelValue];
}

- (CGFloat)animValueForBar:(int)index
{
    if(self.modelLayer == self)
    {
        return 1.f;
    }
    
    CGFloat result = _appearAnimationDuration - _delayBarAnimation * index;
    
    result = MAX(0, MIN(1, result));
    
    return [_timingFunction valueForX:result];
}

- (CGFloat)animValueForLegend:(int)index
{
    if(self.modelLayer == self)
    {
        return 1.f;
    }
    
    CGFloat result = _appearAnimationDuration - _delayLegendAnimation * index;
    
    result = MAX(0, MIN(1, result));
    
    return [_timingFunction valueForX:result];
}


@end