//
//  SlideSegmentView.swift
//  swift翻译
//
//  Created by zhongyuan on 2018/3/20.
//  Copyright © 2018年 zhongyuan. All rights reserved.
//

import UIKit
import SnapKit

@IBDesignable
class SlideSegmentView: UIView, UIScrollViewDelegate {
    
    /// MARK: -- 属性
    @IBOutlet weak var titleScrollViews: UIScrollView!
    @IBOutlet weak var titleStackViews: UIStackView!
    @IBOutlet weak var contentScrollViews: UIScrollView!
    @IBOutlet weak var contentStackViews: UIStackView!
    @IBOutlet weak var titleStackViewWidthConstraints: NSLayoutConstraint!
    @IBOutlet weak var titleStackViewLeftConstraints: NSLayoutConstraint!
    @IBOutlet weak var titleStackViewRightConstraints: NSLayoutConstraint!
    @IBOutlet weak var UnderlineView: UIView!
    @IBOutlet weak var contentView: UIView!
    @IBOutlet weak var contentStackWidth: NSLayoutConstraint!
    
    var titleColorNormal:UIColor = UIColor.orange//Color_SlideSegmentView_titleColorNormal
    var titleColorSelected:UIColor = UIColor.orange//Color_SlideSegmentView_titleColorSelected
    var titleFont:UIFont = UIFont.systemFont(ofSize: 15)
    var underlineViewBgColor:UIColor = UIColor.orange //Color_family_normal
    var titleViews:[UIView] = [UIView]()
    var curPageIndex =  0
    
    var titles:Array<String> = []             /**<   标签标题 */
    {
        didSet{
            for subview:UIView in titleStackViews.arrangedSubviews {
                titleStackViews.removeArrangedSubview(subview)
            }
            
            for subview:UIView in contentStackViews.arrangedSubviews {
                contentStackViews.removeArrangedSubview(subview)
            }
            
            titleScrollViews.contentOffset = CGPoint.zero
            contentScrollViews.contentOffset = CGPoint.zero
            
            for title in titles {
                
                let btn:UIButton = UIButton.init(type: .custom)
                btn.titleLabel?.font = titleFont
                btn.setTitleColor(titleColorNormal, for: .normal)
                btn.setTitleColor(titleColorSelected, for: .selected)
                btn.setTitle(title, for: .normal)
                btn.sizeToFit()
                btn.addTarget(self, action:#selector(onTitleButtomClick( sender: )), for: .touchUpInside)
                
                titleStackViews.addArrangedSubview(btn)
            }
            
            self.refreshTitleSpace()
            
            contentScrollViews.contentSize = CGSize(width: width * CGFloat(titles.count), height: contentScrollViews.superview!.height - contentScrollViews.y)
            contentStackWidth.constant = CGFloat(titles.count) * width
            
            for _ in 0..<titles.count {
                let subView = UIView()
                subView.backgroundColor = UIColor.clear
                contentStackViews.addArrangedSubview(subView)
            }
            
            titleViews = []
            for btn in titleStackViews.arrangedSubviews {
                titleViews.append(btn)
            }
            
            pageIndex = 0
        }
    }
    
    /**<   配置内容视图 */
    var contentViews:Array<UIView> = []
    {
        didSet{
            let count = contentViews.count
            if count != viewControllers.count {
                viewControllers = []
            }else {
                for i in 0..<count{
                    if viewControllers[i].view != contentViews[i]{
                        viewControllers = []
                    }
                }
            }
            
            for i in 0..<count {
                let contentView:UIView = contentViews[i]
                let superview:UIView = contentStackViews.arrangedSubviews[i]
                superview.addSubview(contentView)
                contentView.snp.makeConstraints({ (mark) in
                    mark.edges.equalTo(superview)
                })
            }
        }
    }
    
    /**<   配置内容视图控制器 */
    var viewControllers: Array<UIViewController> = []
    {
        didSet{
            if(viewControllers.count > 0){
                var views:Array<UIView> = []
                for vc in viewControllers {
                    views.append(vc.view)
                }
                self.contentViews = views
            }
        }
    }
    
    var didScrollToIndex:((Int)->())?         /**<   滚动到第index页时回调 */
    var space:CGFloat = 30                       /**<   各标题的间隔 */
    var pageIndex:Int                     /**<   当前页index */
    {
        set{
            self.setPageIndex(pageIndex: newValue , animated: false)
        }
        get{
            for titleBtn in titleStackViews.arrangedSubviews
            {
                if (titleBtn as! UIButton).isSelected
                {
                    return titleStackViews.arrangedSubviews.firstIndex(of: titleBtn)!
                }
            }
            return 0
        }
    }
    
    func setPageIndex(pageIndex:Int,animated:Bool){
        self.layoutIfNeeded()
        
        if titleStackViews.arrangedSubviews.count <= pageIndex {
            return
        }
        
        for titleBtn in titleStackViews.arrangedSubviews {
            (titleBtn as! UIButton).isSelected = false
        }
        
        let sender:UIButton = titleStackViews.arrangedSubviews[pageIndex] as! UIButton
        sender.isSelected = true
        
        // 滚动标题栏、内容栏
        let count = self.titleViews.count
        let startX = self.titleViews[pageIndex].frame.origin.x
        let isRight = (pageIndex - self.curPageIndex) > 0
        let isLeft = (pageIndex - self.curPageIndex) < 0
        let width = self.titleViews[pageIndex].width + self.space
        let endX = startX + width
        let x = self.width * CGFloat(pageIndex)
        let _animated = abs(contentScrollViews.contentOffset.x - x) <= self.width
        contentScrollViews.setContentOffset(CGPoint(x: x, y: 0), animated: animated && _animated)
        
        //向左滑，且左边有未显示的部分
        if isLeft,self.titleScrollViews.contentOffset.x > 0 {
            //若当前单元格的前一个单元格已到最左边或之前，则向右滑
            if (startX - self.titleScrollViews.contentOffset.x - width) < 10 {
                var offectX = (startX - width)
                offectX = max(offectX, 0)
                self.titleScrollViews.setContentOffset(CGPoint.init(x: offectX, y: 0), animated: animated)
            }
        }
        //向右滑，且右边有未显示的部分
        if isRight,(self.titleScrollViews.contentOffset.x + self.width)  < self.titleViews[count - 1].right{
            //若当前单元格的后一个单元格已到最右边，则向左滑
            if (endX + width) > (self.width - 10) {
                var offectX = (endX + width - self.width)
                offectX = min(offectX, self.titleViews[count - 1].right - self.width + space)
                self.titleScrollViews.setContentOffset(CGPoint.init(x: offectX, y: 0), animated: animated)
            }
        }
        
        titleScrollViews.layoutIfNeeded()
        
        UIView.animate(withDuration: 0.25) {
            
            let strW:CGFloat = (self.titleStackViews.subviews[pageIndex] as! UIButton).width
            self.UnderlineView.snp.remakeConstraints({ (mark) in
                mark.bottom.equalTo(self.titleScrollViews)
                mark.centerX.equalTo(sender)
                mark.width.equalTo(strW)
                mark.height.equalTo(3)
            })
            
            self.titleScrollViews.layoutIfNeeded()
        }
        
        if didScrollToIndex != nil{
            didScrollToIndex!(pageIndex)
        }
        
        curPageIndex =  pageIndex
    }
    
    override func awakeFromNib() {
        super.awakeFromNib()

        contentScrollViews.delegate = self
        UnderlineView.backgroundColor = underlineViewBgColor
    }
    
    override func layoutSubviews() {
        super.layoutSubviews()
        
        self.refreshTitleSpace()
        contentScrollViews.contentSize = CGSize.init(width: self.width * CGFloat(titles.count), height: contentScrollViews.superview!.height - contentScrollViews.y)
        contentStackWidth.constant = CGFloat(titles.count) * self.width
    }
    
    @objc func onTitleButtomClick(sender:UIButton) -> Void {
        self.setPageIndex(pageIndex: titleStackViews.arrangedSubviews.firstIndex(of: sender)!, animated: true)
    }
    
    func refreshTitleSpace() {
        if titles.count == 0 {
            return
        }
        
        let calculativeWidth: (String) -> CGFloat = { str in
            return str.boundingRect(with: CGSize.init(width: 999999,
                                                      height: self.titleFont.pointSize),
                                    options: [.usesLineFragmentOrigin,
                                              .usesFontLeading],
                                    attributes: [NSAttributedString.Key.font: self.titleFont],
                                    context: nil).size.width  //ld??
        }
        
        var len = calculativeWidth({ () -> String in
            var str = String()
            for title in self.titles {
                str.append(title)
            }
            return str
            }())
//        dPrint("总的宽度: \(len)")
        
        len += CGFloat(titles.count) // 这里每个title加上1是因为button的宽度和string的宽度有不到一的差距
        
        var flag = true
        let averageWith = (width - space * CGFloat(titles.count)) / CGFloat(titles.count) // 平均宽度
        
        for title in self.titles {
            
            let length = calculativeWidth(title)
            if length > averageWith {
                
                flag = false
                break
            }
        }
        
        if len + space * CGFloat(titles.count) < self.width && flag {
            titleStackViewLeftConstraints.constant = space/2
            titleStackViewRightConstraints.constant = space/2
            titleStackViewWidthConstraints.constant = self.width - space
            titleStackViews.distribution = .fillEqually
            titleStackViews.spacing = space
        } else {
            titleStackViews.distribution = .fill
            titleStackViewWidthConstraints.constant = len + space * CGFloat((titles.count - 1))
            titleStackViewLeftConstraints.constant = space/2
            titleStackViewRightConstraints.constant = space/2
            titleStackViews.spacing = space
        }
    }
    
    //MARK: - UIScrollViewDelegate
    func scrollViewWillEndDragging(_ scrollView: UIScrollView,
                                   withVelocity velocity: CGPoint,
                                   targetContentOffset: UnsafeMutablePointer<CGPoint>) {
        if (scrollView == contentScrollViews) {
            let i = (Int)(targetContentOffset.pointee.x / scrollView.width)
            self.setPageIndex(pageIndex: i, animated: true)
        }
    }
    
    func scrollViewDidScroll(_ scrollView: UIScrollView) {
        
    }
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        
        initialFromXib()
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        
        initialFromXib()
    }
    
    func initialFromXib() {
        let bundle = Bundle.init(for: self.classForCoder)
        let nib = UINib(nibName: "SlideSegmentView", bundle: bundle)
        contentView = nib.instantiate(withOwner: self, options: nil)[0] as? UIView
        contentView.frame = bounds
        addSubview(contentView)
    }
}

//MARK: -String 扩展
extension String{
    func width() -> (UIFont,CGFloat)->CGFloat {
        return { (font:UIFont,height:CGFloat) -> CGFloat in
            if  (self as NSString).length == 0 {
                return 0
            }
            
            return self.boundingRect(with: CGSize.init(width: 0,
                                                       height: height),
                                     options: [.usesLineFragmentOrigin,
                                               .usesFontLeading],
                                     attributes: [NSAttributedString.Key.font:font],
                                     context: nil).size.width
        }
    }
}