//
//  IBTextView.swift
//  MTP2_iOS
//
//  Created by Handy_Cao on 2018/8/9.
//  Copyright © 2018年 Muchinfo. All rights reserved.
//

import UIKit

@IBDesignable
class IBTextView: UITextView, UITextViewDelegate {
    
    /// 默认最大行高
    var maxRowHeight:CGFloat = 100
    /// 默认样式
    var borderStyle: IBTextViewStyle = .default {
        didSet {
            switch borderStyle {
            case .default:
                defaultSetting()
            case .NoneBorder:
                noneBorderSetting()
            case .custom:
                customBorderSetting()
            }
        }
    }
    /// IBTextView高度变化通知
    static let RowChangeNotification = NSNotification.Name.init("IBTextViewRowChange")
    /// delegate
    weak var IBTextViewDelegate: UITextViewDelegate?
    
    /// 样式
    ///
    /// - `default`: 默认样式
    /// - NoneBorder: 无边框样式
    /// - custom: 自定义样式，由IB决定
    enum IBTextViewStyle {
        case `default`
        case NoneBorder
        case custom
    }
    
    @objc required public init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        
        #if swift(>=4.2)
        let UITextViewTextDidChange = UITextView.textDidChangeNotification
        #else
        let UITextViewTextDidChange = Notification.Name.UITextViewTextDidChange
        #endif
        
        NotificationCenter.default.addObserver(self, selector: #selector(self.refreshPlaceholder), name:UITextViewTextDidChange, object: self)
        delegate = self
    }
    
    @objc override public init(frame: CGRect, textContainer: NSTextContainer?) {
        super.init(frame: frame, textContainer: textContainer)
        
        #if swift(>=4.2)
        let notificationName = UITextView.textDidChangeNotification
        #else
        let notificationName = Notification.Name.UITextViewTextDidChange
        #endif
        
        NotificationCenter.default.addObserver(self, selector: #selector(self.refreshPlaceholder), name: notificationName, object: self)
        delegate = self
    }
    
    @objc override open func awakeFromNib() {
        super.awakeFromNib()
        
        #if swift(>=4.2)
        let UITextViewTextDidChange = UITextView.textDidChangeNotification
        #else
        let UITextViewTextDidChange = Notification.Name.UITextViewTextDidChange
        #endif
        
        NotificationCenter.default.addObserver(self, selector: #selector(self.refreshPlaceholder), name: UITextViewTextDidChange, object: self)
        delegate = self
    }
    
    private func defaultSetting() {
        layer.borderColor = UIColor(red: 215.0 / 255.0, green: 215.0 / 255.0, blue: 215.0 / 255.0, alpha: 1).cgColor
        layer.borderWidth = 0.6
        layer.cornerRadius = 6.0
    }
    
    private func noneBorderSetting() {
        layer.borderColor = nil
        layer.borderWidth = 0
        layer.cornerRadius = 0
    }
    
    private func customBorderSetting() {
        // 由IB决定
    }
    
    deinit {
        placeholderLabel.removeFromSuperview()
        NotificationCenter.default.removeObserver(self)
    }
    
    private var placeholderInsets : UIEdgeInsets {
        return UIEdgeInsets(top: self.textContainerInset.top, left: self.textContainerInset.left + self.textContainer.lineFragmentPadding, bottom: self.textContainerInset.bottom, right: self.textContainerInset.right + self.textContainer.lineFragmentPadding)
    }
    
    private var placeholderExpectedFrame : CGRect {
        let placeholderInsets = self.placeholderInsets
        let maxWidth = self.frame.width-placeholderInsets.left-placeholderInsets.right
        let expectedSize = placeholderLabel.sizeThatFits(CGSize(width: maxWidth, height: self.frame.height-placeholderInsets.top-placeholderInsets.bottom))
        
        return CGRect(x: placeholderInsets.left, y: placeholderInsets.top, width: maxWidth, height: expectedSize.height)
    }
    
    lazy var placeholderLabel: UILabel = {
        let label = UILabel()
        
        label.autoresizingMask = [.flexibleWidth, .flexibleHeight]
        label.lineBreakMode = .byWordWrapping
        label.numberOfLines = 0
        label.font = self.font
        label.textAlignment = self.textAlignment
        label.backgroundColor = UIColor.clear
        label.textColor = UIColor(white: 0.7, alpha: 1.0)
        label.alpha = 0
        self.addSubview(label)
        
        return label
    }()
    
    /** @abstract To set textView's placeholder text color. */
    @IBInspectable open var placeholderTextColor : UIColor? {
        
        get {
            return placeholderLabel.textColor
        }
        
        set {
            placeholderLabel.textColor = newValue
        }
    }
    
    /** @abstract To set textView's placeholder text. Default is nil.    */
    @IBInspectable open var placeholder : String? {
        
        get {
            return placeholderLabel.text
        }
        
        set {
            placeholderLabel.text = newValue
            refreshPlaceholder()
        }
    }
    
    /** @abstract To set textView's borderColor. Default is nil.    */
    @IBInspectable open var borderColor : UIColor? {
        
        get {
            if let borderColor = layer.borderColor {
                return UIColor(cgColor: borderColor)
            } else {
                return nil
            }
        }
        
        set {
            if let newValue = newValue {
                layer.borderColor = newValue.cgColor
            } else {
                layer.borderColor = UIColor(red: 215.0 / 255.0, green: 215.0 / 255.0, blue: 215.0 / 255.0, alpha: 1).cgColor
            }
        }
    }
    
    /** @abstract To set textView's borderWidth. Default is 0.    */
    @IBInspectable open var borderWidth : CGFloat {
        
        get {
            return layer.borderWidth
        }
        
        set {
            layer.borderWidth = newValue
        }
    }
    
    /** @abstract To set textView's cornerRadius. Default is 0.    */
    @IBInspectable open var cornerRadius : CGFloat {
        
        get {
            return layer.cornerRadius
        }
        
        set {
            layer.cornerRadius = newValue
        }
    }
    
    
    
    /** @abstract To set textView's placeholder attributed text. Default is nil.    */
    open var attributedPlaceholder: NSAttributedString? {
        get {
            return placeholderLabel.attributedText
        }
        
        set {
            placeholderLabel.attributedText = newValue
            refreshPlaceholder()
        }
    }
    
    @objc override open func layoutSubviews() {
        super.layoutSubviews()
        
        placeholderLabel.frame = placeholderExpectedFrame
    }
    
    @objc internal func refreshPlaceholder() {
        
        if !text.isEmpty || !attributedText.string.isEmpty {
            placeholderLabel.alpha = 0
        } else {
            placeholderLabel.alpha = 1
        }
    }
    
    @objc override open var text: String! {
        
        didSet {
            refreshPlaceholder()
        }
    }
    
    open override var attributedText: NSAttributedString! {
        
        didSet {
            refreshPlaceholder()
        }
    }
    
    @objc override open var font : UIFont? {
        
        didSet {
            
            if let unwrappedFont = font {
                placeholderLabel.font = unwrappedFont
            } else {
                placeholderLabel.font = UIFont.systemFont(ofSize: 12)
            }
        }
    }
    
    @objc override open var textAlignment: NSTextAlignment
        {
        didSet {
            placeholderLabel.textAlignment = textAlignment
        }
    }
    
    @objc override internal var delegate : UITextViewDelegate? {
        
        get {
            refreshPlaceholder()
            return super.delegate
        }
        
        set {
            super.delegate = newValue
        }
    }
    
    @objc override open var intrinsicContentSize: CGSize {
        guard !hasText else {
            var newSize = super.intrinsicContentSize
            newSize.height = 30
            return newSize
        }
        
        var newSize = super.intrinsicContentSize
        let placeholderInsets = self.placeholderInsets
        newSize.height = placeholderExpectedFrame.height + placeholderInsets.top + placeholderInsets.bottom
        
        return newSize
    }
    
    //MARK: -  UITextViewDelegate
    func textViewDidChange(_ textView: UITextView) {
        let frame = textView.frame
        let constraintSize = CGSize(width: frame.width, height: CGFloat(MAXFLOAT))
        let size = textView.sizeThatFits(constraintSize)
        if size.height <= maxRowHeight {
            let constraints = textView.constraints.filter({ $0.firstAttribute == NSLayoutConstraint.Attribute.height })
            if constraints.count > 0 {
                textView.removeConstraints(constraints)
            }
            let newConstraints = NSLayoutConstraint(item: textView, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1.0, constant: size.height)
            newConstraints.priority = UILayoutPriority(rawValue: 999)
            textView.addConstraint(newConstraints)
            
            NotificationCenter.default.post(name: IBTextView.RowChangeNotification, object: nil)
        } else {
            let constraints = textView.constraints.filter({ $0.firstAttribute == NSLayoutConstraint.Attribute.height })
            if constraints.count > 0 {
                textView.removeConstraints(constraints)
            }
            let newConstraints = NSLayoutConstraint(item: textView, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1.0, constant: maxRowHeight)
            newConstraints.priority = UILayoutPriority(rawValue: 999)
            textView.addConstraint(newConstraints)
            
            NotificationCenter.default.post(name: IBTextView.RowChangeNotification, object: nil)
        }
    }
    
    func textViewShouldBeginEditing(_ textView: UITextView) -> Bool {
        return IBTextViewDelegate?.textViewShouldEndEditing?(textView) ?? true
    }
    
    func textViewShouldEndEditing(_ textView: UITextView) -> Bool {
        return IBTextViewDelegate?.textViewShouldEndEditing?(textView) ?? true
    }
    
    func textViewDidBeginEditing(_ textView: UITextView) {
        IBTextViewDelegate?.textViewDidBeginEditing?(textView)
    }
    
    func textViewDidEndEditing(_ textView: UITextView) {
        IBTextViewDelegate?.textViewDidEndEditing?(textView)
    }
    
    func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
        return IBTextViewDelegate?.textView?(textView, shouldChangeTextIn: range, replacementText: text) ?? true
    }
}