/**
 * Copyright (c) 2015-present, Horcrux.
 * All rights reserved.
 *
 * This source code is licensed under the MIT-style license found in the
 * LICENSE file in the root directory of this source tree.
 */

/*
 Erica Sadun, http://ericasadun.com
 iPhone Developer's Cookbook, 6.x Edition
 BSD License, Use at your own risk
 */

#import "UIBezierPath-Points.h"

#define POINTSTRING(_CGPOINT_) (NSStringFromCGPoint(_CGPOINT_))
#define VALUE(_INDEX_) [NSValue valueWithCGPoint:points[_INDEX_]]
#define POINT(_INDEX_) [(NSValue *)[points objectAtIndex:_INDEX_] CGPointValue]

// Return distance between two points
static float distance (CGPoint p1, CGPoint p2)
{
    float dx = p2.x - p1.x;
    float dy = p2.y - p1.y;
    
    return sqrt(dx*dx + dy*dy);
}

@implementation UIBezierPath (Points)
void getPointsFromBezier(void *info, const CGPathElement *element)
{
    NSMutableArray *bezierPoints = (__bridge NSMutableArray *)info;
    CGPathElementType type = element->type;
    CGPoint *points = element->points;
    if (type != kCGPathElementCloseSubpath)
    {
        if ((type == kCGPathElementAddLineToPoint) ||
            (type == kCGPathElementMoveToPoint))
            [bezierPoints addObject:VALUE(0)];
        else if (type == kCGPathElementAddQuadCurveToPoint)
            [bezierPoints addObject:VALUE(1)];
        else if (type == kCGPathElementAddCurveToPoint)
            [bezierPoints addObject:VALUE(2)];
    }
}

- (NSArray *)points
{
    NSMutableArray *points = [NSMutableArray array];
    CGPathApply(self.CGPath, (__bridge void *)points, getPointsFromBezier);
    return points;
}

// Return a Bezier path buit with the supplied points
+ (UIBezierPath *) pathWithPoints: (NSArray *) points
{
    UIBezierPath *path = [UIBezierPath bezierPath];
    if (points.count == 0) return path;
    [path moveToPoint:POINT(0)];
    for (int i = 1; i < points.count; i++)
        [path addLineToPoint:POINT(i)];
    return path;
}

- (CGFloat) length
{
    NSArray *points = self.points;
    float totalPointLength = 0.0f;
    for (int i = 1; i < points.count; i++)
        totalPointLength += distance(POINT(i), POINT(i-1));
    return totalPointLength;
}

- (NSArray *) pointPercentArray
{
    // Use total length to calculate the percent of path consumed at each control point
    NSArray *points = self.points;
    int pointCount = points.count;
    
    float totalPointLength = self.length;
    float distanceTravelled = 0.0f;
    
    NSMutableArray *pointPercentArray = [NSMutableArray array];
    [pointPercentArray addObject:@(0.0)];
    
    for (int i = 1; i < pointCount; i++)
    {
        distanceTravelled += distance(POINT(i), POINT(i-1));
        [pointPercentArray addObject:@(distanceTravelled / totalPointLength)];
    }
    
    // Add a final item just to stop with. Probably not needed.
    [pointPercentArray addObject:[NSNumber numberWithFloat:1.1f]]; // 110%
    
    return pointPercentArray;
}

- (CGPoint) pointAtPercent: (CGFloat) percent withSlope: (CGPoint *) slope
{
    NSArray *points = self.points;
    NSArray *percentArray = self.pointPercentArray;
    CFIndex lastPointIndex = points.count - 1;
    
    if (!points.count) {
        return CGPointZero;
    }
    
    // Check for 0% and 100%
    if (percent <= 0.0f) {
        return POINT(0);
    }
    if (percent >= 1.0f) {
        return POINT(lastPointIndex);
    }
    
    // Find a corresponding pair of points in the path
    CFIndex index = 1;
    while ((index < percentArray.count) &&
           (percent > ((NSNumber *)percentArray[index]).floatValue)) {
        index++;
    }
    
    // This should not happen.
    if (index > lastPointIndex) {
        return POINT(lastPointIndex);
    }
    
    // Calculate the intermediate distance between the two points
    CGPoint point1 = POINT(index -1);
    CGPoint point2 = POINT(index);
    
    float percent1 = [[percentArray objectAtIndex:index - 1] floatValue];
    float percent2 = [[percentArray objectAtIndex:index] floatValue];
    float percentOffset = (percent - percent1) / (percent2 - percent1);
    
    float dx = point2.x - point1.x;
    float dy = point2.y - point1.y;
    
    // Store dy, dx for retrieving arctan
    if (slope) {
        *slope = CGPointMake(dx, dy);
    }
    
    // Calculate new point
    CGFloat newX = point1.x + (percentOffset * dx);
    CGFloat newY = point1.y + (percentOffset * dy);
    CGPoint targetPoint = CGPointMake(newX, newY);
    
    return targetPoint;
}

void getBezierElements(void *info, const CGPathElement *element)
{
    NSMutableArray *bezierElements = (__bridge NSMutableArray *)info;
    CGPathElementType type = element->type;
    CGPoint *points = element->points;
    
    switch (type)
    {
        case kCGPathElementCloseSubpath:
            [bezierElements addObject:@[@(type)]];
            break;
        case kCGPathElementMoveToPoint:
        case kCGPathElementAddLineToPoint:
            [bezierElements addObject:@[@(type), VALUE(0)]];
            break;
        case kCGPathElementAddQuadCurveToPoint:
            [bezierElements addObject:@[@(type), VALUE(0), VALUE(1)]];
            break;
        case kCGPathElementAddCurveToPoint:
            [bezierElements addObject:@[@(type), VALUE(0), VALUE(1), VALUE(2)]];
            break;
    }
}

- (NSArray *) bezierElements
{
    NSMutableArray *elements = [NSMutableArray array];
    CGPathApply(self.CGPath, (__bridge void *)elements, getBezierElements);
    return elements;
}

+ (UIBezierPath *) pathWithElements: (NSArray *) elements
{
    UIBezierPath *path = [UIBezierPath bezierPath];
    if (elements.count == 0) return path;
    
    for (NSArray *points in elements)
    {
        if (!points.count) continue;
        CGPathElementType elementType = [points[0] integerValue];
        switch (elementType)
        {
            case kCGPathElementCloseSubpath:
                [path closePath];
                break;
            case kCGPathElementMoveToPoint:
                if (points.count == 2)
                    [path moveToPoint:POINT(1)];
                break;
            case kCGPathElementAddLineToPoint:
                if (points.count == 2)
                    [path addLineToPoint:POINT(1)];
                break;
            case kCGPathElementAddQuadCurveToPoint:
                if (points.count == 3)
                    [path addQuadCurveToPoint:POINT(2) controlPoint:POINT(1)];
                break;
            case kCGPathElementAddCurveToPoint:
                if (points.count == 4)
                    [path addCurveToPoint:POINT(3) controlPoint1:POINT(1) controlPoint2:POINT(2)];
                break;
        }
    }
    
    return path;
}
@end