//

// MessageView.swift

// MessageView

//

// Created by Ryan Nystrom on 12/20/17.

// Copyright © 2017 Ryan Nystrom. All rights reserved.

//

import UIKit

public final class MessageView: UIView, MessageTextViewListener {

public let textView = MessageTextView()

internal weak var delegate: MessageViewDelegate?

internal let button = UIButton()

internal let UITextViewContentSizeKeyPath = #keyPath(UITextView.contentSize)

internal let topBorderLayer = CALayer()

internal var contentView: UIView?

internal var buttonAction: Selector?

internal override init(frame: CGRect) {

super.init(frame: frame)

backgroundColor = .white

addSubview(textView)

addSubview(button)

layer.addSublayer(topBorderLayer)

// setup text view

textView.contentInset = .zero

textView.textContainerInset = .zero

textView.backgroundColor = .clear

textView.addObserver(self, forKeyPath: UITextViewContentSizeKeyPath, options: [.new], context: nil)

textView.font = .systemFont(ofSize: UIFont.systemFontSize)

textView.add(listener: self)

// setup TextKit props to defaults

textView.textContainer.exclusionPaths = []

textView.textContainer.maximumNumberOfLines = 0

textView.textContainer.lineFragmentPadding = 0

textView.layoutManager.allowsNonContiguousLayout = false

textView.layoutManager.hyphenationFactor = 0

textView.layoutManager.showsInvisibleCharacters = false

textView.layoutManager.showsControlCharacters = false

textView.layoutManager.usesFontLeading = true

// setup send button

button.titleEdgeInsets = .zero

button.contentEdgeInsets = .zero

button.imageEdgeInsets = .zero

updateEmptyTextStates()

}

public required init?(coder aDecoder: NSCoder) {

fatalError("init(coder:) has not been implemented")

}

deinit {

textView.removeObserver(self, forKeyPath: UITextViewContentSizeKeyPath)

}

// MARK: Public API

public var font: UIFont? {

get { return textView.font }

set {

textView.font = newValue

delegate?.wantsLayout(messageView: self)

}

}

public var text: String {

get { return textView.text ?? "" }

set {

textView.text = newValue

delegate?.wantsLayout(messageView: self)

updateEmptyTextStates()

}

}

public var inset: UIEdgeInsets = .zero {

didSet {

setNeedsLayout()

delegate?.wantsLayout(messageView: self)

}

}

public var buttonLeftInset: CGFloat = 0 {

didSet { setNeedsLayout() }

}

public func set(buttonIcon: UIImage?, for state: UIControlState) {

button.setImage(buttonIcon, for: state)

buttonLayoutDidChange()

}

public func set(buttonTitle: String, for state: UIControlState) {

button.setTitle(buttonTitle, for: state)

buttonLayoutDidChange()

}

public var buttonTint: UIColor {

get { return button.tintColor }

set {

button.tintColor = newValue

button.setTitleColor(newValue, for: .normal)

button.imageView?.tintColor = newValue

}

}

public var maxLineCount: Int = 4 {

didSet {

delegate?.wantsLayout(messageView: self)

}

}

public func add(contentView: UIView) {

self.contentView?.removeFromSuperview()

assert(contentView.bounds.height > 0, "Must have a non-zero content height")

self.contentView = contentView

addSubview(contentView)

setNeedsLayout()

delegate?.wantsLayout(messageView: self)

}

public var keyboardType: UIKeyboardType {

get { return textView.keyboardType }

set { textView.keyboardType = newValue }

}

public func addButton(target: Any, action: Selector) {

button.addTarget(target, action: action, for: .touchUpInside)

buttonAction = action

}

public override var keyCommands: [UIKeyCommand]? {

guard let action = buttonAction else { return nil }

return [UIKeyCommand(input: "\r", modifierFlags: .command, action: action)]

}

// MARK: Overrides

public override func layoutSubviews() {

super.layoutSubviews()

topBorderLayer.frame = CGRect(

x: bounds.minX,

y: bounds.minY,

width: bounds.width,

height: 1 / UIScreen.main.scale

)

let safeBounds = CGRect(

x: bounds.minX + util_safeAreaInsets.left,

y: bounds.minY,

width: bounds.width - util_safeAreaInsets.left - util_safeAreaInsets.right,

height: bounds.height

)

let insetBounds = UIEdgeInsetsInsetRect(safeBounds, inset)

let buttonSize = button.bounds.size

let textViewFrame = CGRect(

x: insetBounds.minX,

y: insetBounds.minY,

width: insetBounds.width - buttonSize.width - buttonLeftInset,

height: textViewHeight

)

textView.frame = textViewFrame

// adjust by bottom offset so content is flush w/ text view

button.frame = CGRect(

x: textViewFrame.maxX + buttonLeftInset,

y: textViewFrame.maxY - buttonSize.height + button.bottomHeightOffset,

width: buttonSize.width,

height: buttonSize.height

)

let contentY = textViewFrame.maxY + inset.bottom

contentView?.frame = CGRect(

x: safeBounds.minX,

y: contentY,

width: safeBounds.width,

height: bounds.height - contentY - util_safeAreaInsets.bottom

)

}

public override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {

if keyPath == UITextViewContentSizeKeyPath {

textViewContentSizeDidChange()

}

}

public override func resignFirstResponder() -> Bool {

return textView.resignFirstResponder()

}

// MARK: Private API

internal var height: CGFloat {

return inset.top

+ inset.bottom

+ textViewHeight

+ (contentView?.bounds.height ?? 0)

}

internal var textViewHeight: CGFloat {

return min(maxHeight, max(textView.font?.lineHeight ?? 0, textView.contentSize.height))

}

internal var maxHeight: CGFloat {

return (font?.lineHeight ?? 0) * CGFloat(maxLineCount)

}

internal func updateEmptyTextStates() {

let isEmpty = text.isEmpty

button.isEnabled = !isEmpty

button.alpha = isEmpty ? 0.25 : 1

}

internal func buttonLayoutDidChange() {

button.sizeToFit()

setNeedsLayout()

}

internal func textViewContentSizeDidChange() {

delegate?.sizeDidChange(messageView: self)

textView.alwaysBounceVertical = textView.contentSize.height > maxHeight

}

// MARK: MessageTextViewListener

public func didChange(textView: MessageTextView) {

updateEmptyTextStates()

}

public func didChangeSelection(textView: MessageTextView) {

delegate?.selectionDidChange(messageView: self)

}

public func willChangeRange(textView: MessageTextView, to range: NSRange) {}

}