//
// ViewController.m
// SideViewController
//
// Created by YouXianMing on 16/6/6.
// Copyright © 2016年 YouXianMing. All rights reserved.
//

#import "ViewController.h"
#import "LeftViewController.h"
#import "MainViewController.h"
#import "UIView+SetRect.h"

@interface ViewController () {
 
 CGFloat _screenWidth;
}

@property (nonatomic, strong) UIPanGestureRecognizer *panGesture;
@property (nonatomic)   CGPoint     panBeginPoint;

@property (nonatomic, strong) LeftViewController  *leftViewController;
@property (nonatomic, strong) UIView     *leftView;

@property (nonatomic, strong) MainViewController  *mainViewController;
@property (nonatomic, strong) UIView     *mainView;

@end

@implementation ViewController

- (void)viewDidLoad {
 
 [super viewDidLoad];
 
 // Init some value.
 _screenWidth = Width;
 
 // Add backgroundView.
 UIImageView *backgroundView = [[UIImageView alloc] initWithFrame:self.view.bounds];
 backgroundView.image  = [UIImage imageNamed:@"back"];
 [self.view addSubview:backgroundView];
 
 // LeftViewController
 self.leftViewController = [[LeftViewController alloc] init];
 self.leftView   = self.leftViewController.view;
 [self.view addSubview:self.leftView];
 
 // MainViewController
 self.mainViewController = [[MainViewController alloc] init];
 self.mainView   = self.mainViewController.view;
 [self.view addSubview:self.mainView];
 
 // Pan gesture.
 self.panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(panGestureEvent:)];
 [self.mainView addGestureRecognizer:self.panGesture];
}

- (void)panGestureEvent:(UIPanGestureRecognizer *)gesture {
 
 CGPoint translation = [gesture translationInView:gesture.view];
 CGPoint velocity = [gesture velocityInView:gesture.view];
 
 CGFloat gap    = _screenWidth / 3.f * 2;
 CGFloat sensitivePosition = _screenWidth / 2.f;
 
 if (velocity.x < 0 && _mainView.x <= 0) {
  
  // 过滤掉向左侧滑过头的情形
  _mainView.x = 0.f;
  
 } else {
  
  if (gesture.state == UIGestureRecognizerStateBegan) {
   
   // 开始
   _panBeginPoint = translation;
   
   if (_mainView.x >= sensitivePosition) {
    
    _panBeginPoint.x -= gap;
   }
   
  } else if (gesture.state == UIGestureRecognizerStateChanged) {
   
   // 值变化
   _mainView.x = translation.x - _panBeginPoint.x;
   
   if (_mainView.x <= 0) {
    
    // 过滤掉向左侧滑过头的情形
    _mainView.x = 0.f;
   }
   
  } else if (gesture.state == UIGestureRecognizerStateEnded) {
   
   // 结束
   [UIView animateWithDuration:0.20f animations:^{
    
    _mainView.x >= sensitivePosition ? (_mainView.x = gap) : (_mainView.x = 0);
   }];
  }
 }
}

@end