public let textView = MessageTextView()

internal weak var delegate: MessageViewDelegate?

internal let leftButton = ExpandedHitTestButton()

internal let rightButton = ExpandedHitTestButton()

internal let UITextViewContentSizeKeyPath = #keyPath(UITextView.contentSize)

internal let topBorderLayer = CALayer()

internal var contentView: UIView?

internal var rightButtonAction: Selector?

internal var leftButtonInset: CGFloat = 0

internal var rightButtonInset: CGFloat = 0

internal var ignoreLineHeight = false

internal var suppressKVO = false

public enum ButtonPosition {

case left

case right

}

internal var heightOffset: CGFloat = 0

internal override init(frame: CGRect) {

super.init(frame: frame)

backgroundColor = .white

addSubview(leftButton)

addSubview(textView)

addSubview(rightButton)

layer.addSublayer(topBorderLayer)

//Set action button

leftButton.imageEdgeInsets = .zero

leftButton.titleEdgeInsets = .zero

leftButton.contentEdgeInsets = .zero

leftButton.titleLabel?.font = self.font ?? UIFont.systemFont(ofSize: 14)

leftButton.imageView?.contentMode = .scaleAspectFit

leftButton.imageView?.clipsToBounds = true

// setup text view

textView.contentInset = .zero

textView.textContainerInset = .zero

textView.backgroundColor = .clear

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

textView.font = self.font ?? UIFont.systemFont(ofSize: 14)

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

rightButton.imageEdgeInsets = .zero

rightButton.titleEdgeInsets = .zero

rightButton.contentEdgeInsets = .zero

rightButton.titleLabel?.font = self.font ?? UIFont.systemFont(ofSize: 14)

rightButton.imageView?.contentMode = .scaleAspectFit

rightButton.imageView?.clipsToBounds = true

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 showLeftButton: Bool = true {

didSet {

delegate?.wantsLayout(messageView: self)

}

}

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 textViewInset: UIEdgeInsets {

set {

textView.textContainerInset = newValue

setNeedsLayout()

delegate?.wantsLayout(messageView: self)

}

get { return textView.textContainerInset }

}

public var contentInset: UIEdgeInsets {

set {

textView.contentInset = newValue

setNeedsLayout()

delegate?.wantsLayout(messageView: self)

}

get { return textView.contentInset }

}

/// - Parameter accessibilityLabel: A custom `accessibilityLabel` to set on the button.

/// If none is supplied, it will default to the icon's `accessibilityLabel`.

public func setButton(icon: UIImage?, for state: UIControl.State, position: ButtonPosition, accessibilityLabel: String? = nil) {

let button: UIButton

switch position {

case .left:

button = leftButton

case .right:

button = rightButton

}

button.setImage(icon, for: state)

button.accessibilityLabel = accessibilityLabel ?? icon?.accessibilityIdentifier

buttonLayoutDidChange(button: button)

}

/// - Parameter accessibilityLabel: A custom `accessibilityLabel` to set on the button.

/// If none is supplied, it will default to the the supplied `title`.

public func setButton(title: String,backgroundColor: UIColor, for state: UIControl.State, position: ButtonPosition, accessibilityLabel: String? = nil) {

let button: UIButton

switch position {

case .left:

button = leftButton

case .right:

button = rightButton

}

button.setTitle(title, for: state)

button.backgroundColor = backgroundColor

button.accessibilityLabel = accessibilityLabel ?? title

buttonLayoutDidChange(button: button)

}

public var leftButtonTint: UIColor {

get { return leftButton.tintColor }

set {

leftButton.tintColor = newValue

leftButton.setTitleColor(newValue, for: .normal)

leftButton.imageView?.tintColor = newValue

}

}

public var rightButtonTint: UIColor {

get { return rightButton.tintColor }

set {

rightButton.tintColor = newValue

rightButton.setTitleColor(newValue, for: .normal)

rightButton.imageView?.tintColor = newValue

}

}

public var maxHeight: CGFloat = CGFloat.greatestFiniteMagnitude {

didSet {

delegate?.wantsLayout(messageView: self)

}

}

public var maxLineCount: Int = 4 {

didSet {

ignoreLineHeight = maxLineHeight == 0

delegate?.wantsLayout(messageView: self)

}

}

public var maxScreenRatio: CGFloat = 1 {

didSet {

maxScreenRatio = 0...1 ~= maxScreenRatio ? maxScreenRatio : 0

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, position: ButtonPosition) {

let button: UIButton

switch position {

case .left:

button = leftButton

case .right:

button = rightButton

rightButtonAction = action

}

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

}

public override var keyCommands: [UIKeyCommand]? {

guard let action = rightButtonAction else { return nil }

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

}

public func setButton(inset: CGFloat, position: ButtonPosition) {

switch position {

case .left:

leftButtonInset = inset

case .right:

rightButtonInset = inset

}

setNeedsLayout()

}

public func setButton(font: UIFont, position: ButtonPosition) {

let button: UIButton

switch position {

case .left:

button = leftButton

case .right:

button = rightButton

}

button.titleLabel?.font = font

buttonLayoutDidChange(button: button)

}

public var bottomInset: CGFloat = 0 {

didSet {

delegate?.wantsLayout(messageView: self)

}

}

// 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 leftButtonSize = leftButton.bounds.size

let rightButtonSize = rightButton.bounds.size

let textViewY = safeBounds.minY

let textViewHeight = self.textViewHeight

let textViewMaxY = textViewY + textViewHeight

// adjust for font descender so button aligns with the text baseline

let descender, pointSize: CGFloat

if let font = textView.font {

descender = floor(font.descender)

pointSize = ceil(font.pointSize)

} else {

descender = 0

pointSize = 0

}

let buttonYStarter = textViewMaxY - textViewInset.bottom - (pointSize - descender)/2

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

let leftButtonFrame = CGRect(

x: safeBounds.minX + leftButtonInset,

y: buttonYStarter - leftButtonSize.height/2 + leftButton.bottomHeightOffset,

width: leftButtonSize.width,

height: leftButtonSize.height

)

leftButton.frame = showLeftButton ? leftButtonFrame : .zero

let leftButtonMaxX = (showLeftButton ? leftButtonFrame.maxX : 0)

let textViewFrame = CGRect(

x: (showLeftButton ? leftButtonMaxX + leftButtonInset : 0),

y: textViewY,

width: safeBounds.width - leftButtonMaxX - rightButtonSize.width - rightButtonInset,

height: textViewHeight

)

suppressKVO = true

textView.frame = textViewFrame

suppressKVO = false

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

let rightButtonFrame = CGRect(

x: textViewFrame.maxX,

y: buttonYStarter - rightButtonSize.height/2 + rightButton.bottomHeightOffset,

width: rightButtonSize.width,

height: rightButtonSize.height

)

rightButton.frame = rightButtonFrame

contentView?.frame = CGRect(

x: safeBounds.minX,

y: textViewFrame.maxY,

width: safeBounds.width,

height: contentView?.frame.height ?? 0

)

}

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

if suppressKVO == false, keyPath == UITextViewContentSizeKeyPath {

textViewContentSizeDidChange()

}

}

public override func resignFirstResponder() -> Bool {

return textView.resignFirstResponder()

}

// MARK: Private API

internal var height: CGFloat {

return textViewHeight

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

+ bottomInset

}

internal var maxLineHeight: CGFloat {

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

}

internal var maxScreenRatioHeight: CGFloat {

return maxScreenRatio * ((superview?.frame.height ?? 0) - heightOffset)

}

internal var calculatedMaxHeight: CGFloat {

return ignoreLineHeight == true ? min(maxScreenRatioHeight, maxHeight) : min(maxScreenRatioHeight, maxLineHeight, maxHeight)

}

internal var textViewHeight: CGFloat {

return ceil(min(calculatedMaxHeight, textView.contentSize.height))

}

internal func updateEmptyTextStates() {

let isEmpty = text.isEmpty

rightButton.isEnabled = !isEmpty

rightButton.alpha = isEmpty ? 0.25 : 1

}

internal func buttonLayoutDidChange(button: UIButton) {

button.sizeToFit()

setNeedsLayout()

}

internal func textViewContentSizeDidChange() {

delegate?.sizeDidChange(messageView: self)

textView.alwaysBounceVertical = textView.contentSize.height > calculatedMaxHeight

}

// 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) {}