//  _____ _
// |_   _| |_  _ _ ___ ___ _ __  __ _
//   | | | ' \| '_/ -_) -_) '  \/ _` |_
//   |_| |_||_|_| \___\___|_|_|_\__,_(_)
//
// Threema iOS Client
// Copyright (c) 2019-2020 Threema GmbH
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License, version 3,
// as published by the Free Software Foundation.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.

import Foundation

@objc public protocol OEMentionsHelperDelegate: class {
    func mentionSelected(id:Int, name:String)
    func textView(_ growingTextView: HPGrowingTextView!, willChangeHeight height: Float)
    func textView(_ growingTextView: HPGrowingTextView!, shouldChangeTextIn range: NSRange, replacementText text: String!) -> Bool
    func textViewDidChange(_ growingTextView: HPGrowingTextView!)
}


@objc public class OEMentionsHelper: NSObject {
    
    @objc open weak var delegate: OEMentionsHelperDelegate?
    private var oementions: OEMentions
    private var growingTextView: HPGrowingTextView
    private var topLine: UIView
    private var mainView: UIView
    
    private let regex: String = "@\\[[0-9A-Z*@]{8}\\]"
    private var mentionCountBeforeChange: Int = 0
    private var shouldUpdateTextColor: Bool = false
    private var isDictationRunning: Bool = false
    
    @objc required public init(containerView: UIView, chatInputView: HPGrowingTextView, mainView: UIView, sortedContacts: [Contact]) {
        let memberlist = OEMentionsHelper.buildOeObjectsList(sortedContacts: sortedContacts)
        growingTextView = chatInputView
        self.mainView = mainView
        oementions = OEMentions.init(containerView: containerView, textView: chatInputView.internalTextView, mainView: mainView, oeObjects: memberlist)
        topLine = UIView.init()
        topLine.frame.size.height = 1
        topLine.backgroundColor = Colors.hairline()
        topLine.isHidden = true
        mainView.insertSubview(topLine, aboveSubview: oementions.tableView)
        super.init()
        oementions.delegate = self
        chatInputView.delegate = self
        oementions.nameFont = chatInputView.internalTextView.font!
        setupColors()
        oementions.showMentionFullInContainer = false
        oementions.tableView.addObserver(self, forKeyPath: "hidden", options: [.new], context: nil)
    }
        
    @objc public func setupColors() {
        oementions.nameColor = Colors.fontLight()
        oementions.notMentionColor = growingTextView.internalTextView.textColor!
        oementions.changeMentionTableviewBackground(color: Colors.background())
        oementions.changeMentionTableviewSeparatorColor(color: Colors.hairline())
        updateTextColor()
    }
    
    @objc public func formattedMentionText() -> String {
        var textViewText = growingTextView.internalTextView.text
        var difference = 0
        if oementions.mentionsIndexes.count != 0 {
            let mentionsIndexes = oementions.mentionsIndexes.sorted(by: { $0.0 < $1.0 })
            for (index,dict) in mentionsIndexes {
                let length = dict["length"] as! Int
                
                let key = dict["key"] as! String
                let nsRange = NSMakeRange(index + difference, length)
                let range = Range.init(nsRange, in: textViewText!)
                textViewText?.replaceSubrange(range!, with: key)
                
                
                let nameCount = length
                let replaceCount = key.count
                difference = difference + (replaceCount - nameCount)
            }
        }
        return textViewText!
    }
    
    @objc public func addMentions(draft: String) {
        var draftString = draft

        do {
            let mentionRegex = try NSRegularExpression.init(pattern: regex, options: .caseInsensitive)
            
            var finished = false
            var lastNotFoundIndex = -1
            
            while !finished {
                let mentionResult = mentionRegex.matches(in: draftString, options: .reportCompletion, range: NSRange.init(location: 0, length: draftString.utf16.count))
                
                var result: NSTextCheckingResult? = nil
                if lastNotFoundIndex == -1 {
                    result = mentionResult.first
                } else {
                    if mentionResult.count >= lastNotFoundIndex + 2 {
                        result = mentionResult[lastNotFoundIndex + 1]
                    }
                }
                
                if result == nil {
                    finished = true
                    break
                }
                
                let mentionTag = String(draftString[String.Index(utf16Offset: result!.range.location, in: draftString)...String.Index(utf16Offset: result!.range.location + result!.range.length - 1, in: draftString)])
                if mentionTag.count == 11 {
                    let identity = String(mentionTag[String.Index(utf16Offset: 2, in: mentionTag)...String.Index(utf16Offset: 9, in: mentionTag)]).uppercased()
                    let contact = ContactStore.shared().contact(forIdentity: identity)
                    
                    if contact != nil || identity == MyIdentityStore.shared()?.identity || identity == "@@@@@@@@" {
                        var displayName = BundleUtil.localizedString(forKey: "me")
                        
                        if let nickname = MyIdentityStore.shared().pushFromName {
                            if nickname.utf16.count > 0 {
                                displayName = nickname
                            }
                        }
                        
                        if contact != nil {
                            displayName = contact!.mentionName
                        }
                        else if identity == "@@@@@@@@" {
                            displayName = BundleUtil.localizedString(forKey: "mentions_all")
                        }
                        
                        let range = Range.init(result!.range, in: draftString)
                        draftString = draftString.replacingCharacters(in: range!, with: "@\(displayName!)")
                        
                        let dict = ["key": mentionTag, "length": displayName!.utf16.count + 1] as [String : Any]
                        oementions.mentionsIndexes[result!.range.location] = dict
                    } else {
                        let range = Range.init(result!.range, in: draftString)
                        draftString = draftString.replacingCharacters(in: range!, with: "@\(identity)")
                        if lastNotFoundIndex == -1 {
                            lastNotFoundIndex = 0
                        } else {
                            lastNotFoundIndex += 1
                        }
                    }
                } else {
                    if lastNotFoundIndex == -1 {
                        lastNotFoundIndex = 0
                    } else {
                        lastNotFoundIndex += 1
                    }
                }
            }
            growingTextView.text = draftString
            updateTextColor()
        }
        catch {
            print("failed regex draft for mentions")
        }
    }
    
    
    
    @objc public func resetMentionsIndexes() {
        oementions.mentionsIndexes.removeAll()
    }
    
    @objc public func updateContainterViewFrame() {
        // add space on top of input view
        oementions.textViewHeight = growingTextView.frame.size.height + 3.0
        oementions.updatePosition()
        topLine.frame = CGRect.init(x: oementions.tableView.frame.origin.x, y: oementions.tableView.frame.origin.y - 1, width: oementions.tableView.frame.size.width, height: 1)
    }

    @objc public func updateTextColor() {
        if !isDictationRunning {
            var attributes = [NSAttributedString.Key: AnyObject]()
            attributes[.foregroundColor] = oementions.notMentionColor
            attributes[.font] = oementions.nameFont
            if oementions.mentionsIndexes.count != 0 {
                let attributedString: NSMutableAttributedString = NSMutableAttributedString.init(string: oementions.textView!.text, attributes: attributes)
                
                let mentionsIndexes = oementions.mentionsIndexes.sorted(by: { $0.0 < $1.0 })
                for (index,dict) in mentionsIndexes {
                    let length = dict["length"] as! Int
                    attributedString.addAttribute(NSAttributedString.Key.foregroundColor, value: oementions.nameColor, range: NSMakeRange(index, length))
                    attributedString.addAttribute(NSAttributedString.Key.font, value: oementions.nameFont, range: NSMakeRange(index, length))
                    attributedString.addAttribute(NSAttributedString.Key.foregroundColor, value: Colors.fontLink()!, range: NSMakeRange(index, length))
                }
                
                if let selectedRange = oementions.textView!.selectedTextRange {
                    oementions.textView!.attributedText = attributedString
                    // and only if the new position is valid
                    if let newPosition = oementions.textView!.position(from: selectedRange.start, in: UITextLayoutDirection.left, offset: 0) {
                        // set the new position
                        oementions.textView!.selectedTextRange = oementions.textView!.textRange(from: newPosition, to: newPosition)
                    }
                } else {
                    oementions.textView!.attributedText = attributedString
                }
            } else {
                if let selectedRange = oementions.textView!.selectedTextRange {
                    oementions.textView!.attributedText = NSMutableAttributedString.init(string: oementions.textView!.text, attributes: attributes)
                    // and only if the new position is valid
                    if let newPosition = oementions.textView!.position(from: selectedRange.start, in: UITextLayoutDirection.left, offset: 0) {
                        // set the new position
                        oementions.textView!.selectedTextRange = oementions.textView!.textRange(from: newPosition, to: newPosition)
                    }
                } else {
                    oementions.textView!.attributedText = NSMutableAttributedString.init(string: oementions.textView!.text, attributes: attributes)
                }
            }
        }
    }
    
    @objc public func updateOeObjects(sortedContacts: [Contact]) {
        oementions.setOeObjects(oeObjects: OEMentionsHelper.buildOeObjectsList(sortedContacts: sortedContacts))
    }
    
    class func buildOeObjectsList(sortedContacts: [Contact]) -> [OEObject] {
        var memberlist = [OEObject]()
        // add @all contact
        let oeObject = OEObject.init(id: 0, name: "@" + BundleUtil.localizedString(forKey: "all"), key: "@[@@@@@@@@]", object: nil)
        memberlist.append(oeObject)
        
        var i = 1
        for contact in sortedContacts {
            let oeObject = OEObject.init(id: i, name: "@" + contact.displayName, key: "@[\(contact.identity!)]", object: contact)
            memberlist.append(oeObject)
            i += 1
        }
        return memberlist
    }
    
    override public func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
        let tableView = object as! UITableView
        topLine.isHidden = tableView.isHidden
    }
    
    private func startKeyboardObserver() {
        NotificationCenter.default.addObserver(self, selector: #selector(changeInputMode), name: UITextInputMode.currentInputModeDidChangeNotification, object: nil)
    }
    
    private func stopKeyboardObserver() {
        NotificationCenter.default.removeObserver(self)
    }
    
    @objc func changeInputMode(notification: NSNotification) {
        let inputMethod = growingTextView.textInputMode?.primaryLanguage
        if inputMethod == "dictation" {
            isDictationRunning = true
        } else {
            isDictationRunning = false
        }
    }

}

extension OEMentionsHelper: HPGrowingTextViewDelegate {
    
    public func growingTextViewDidBeginEditing(_ growingTextView: HPGrowingTextView!) {
        startKeyboardObserver()
    }

    public func growingTextView(_ growingTextView: HPGrowingTextView!, willChangeHeight height: Float) {
        delegate?.textView(growingTextView, willChangeHeight: height)
    }
    
    public func growingTextView(_ growingTextView: HPGrowingTextView!, didChangeHeight height: Float) {
        updateContainterViewFrame()
    }
    
    public func growingTextView(_ growingTextView: HPGrowingTextView!, shouldChangeTextIn range: NSRange, replacementText text: String!) -> Bool {
        mentionCountBeforeChange = oementions.mentionsIndexes.count
        _ = oementions.textView(growingTextView.internalTextView, shouldChangeTextIn: range, replacementText: text)
        return delegate?.textView(growingTextView, shouldChangeTextIn: range, replacementText: text) ?? true
    }
    
    public func growingTextViewDidChange(_ growingTextView: HPGrowingTextView!) {
        if growingTextView.internalTextView.isFirstResponder {
            oementions.updatePosition()
        }

        if shouldUpdateTextColor == true || (mentionCountBeforeChange > oementions.mentionsIndexes.count && oementions.mentionsIndexes.count == 0) {
            shouldUpdateTextColor = false
            updateTextColor()
        }

        delegate?.textViewDidChange(growingTextView)
    }
    
    public func growingTextViewDidEndEditing(_ growingTextView: HPGrowingTextView!) {
        stopKeyboardObserver()
        oementions.textViewDidEndEditing(growingTextView.internalTextView)
    }
    
}

extension OEMentionsHelper: OEMentionsDelegate {
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath, oeObject: OEObject) -> UITableViewCell {
        let cell:MentionCell = MentionCell.init(style: UITableViewCell.CellStyle.default, reuseIdentifier: "MentionCell")
        cell.backgroundColor = UIColor.clear
        cell.selectionStyle = UITableViewCell.SelectionStyle.none
        if let contact = oeObject.object as? Contact {
            cell.contact = contact
        } else {
            // @all contact
            cell.allContact = true
        }
        return cell
    }
    
    func mentionSelected(id: Int, name: String) {
        delegate?.mentionSelected(id: id, name: name)
        growingTextView.refreshHeight()
        updateTextColor()
    }
    
    func tableViewPositionUpdated() {
        if !oementions.tableView.isHidden {
            topLine.frame = CGRect.init(x: oementions.tableView.frame.origin.x, y: oementions.tableView.frame.origin.y, width: oementions.tableView.frame.size.width, height: 1)
        }
    }
    
    func textViewShouldUpdateTextColor() {
        shouldUpdateTextColor = true
    }
}


class MentionCell : UITableViewCell {
    
    var contact : Contact? {
        didSet {
            avatar.image = AvatarMaker.shared()?.avatar(for: contact!, size: 16.0, masked: true)
            mentionNameLabel.text = contact?.displayName
            mentionIdentityLabel.text = contact?.identity
        }
    }
    
    var allContact: Bool = false {
        didSet {
            avatar.image = AvatarMaker.shared()?.unknownPersonImage()
            mentionNameLabel.text = "@" + BundleUtil.localizedString(forKey: "all")
            mentionIdentityLabel.text = nil
        }
    }
    
    private let mentionNameLabel : UILabel = {
        let lbl = UILabel()
        lbl.textColor = Colors.fontNormal()
        lbl.font = UIFont.systemFont(ofSize: UIFont.systemFontSize)
        lbl.textAlignment = .left
        return lbl
    }()
    
    
    private let mentionIdentityLabel : UILabel = {
        let lbl = UILabel()
        lbl.textColor = Colors.fontNormal()
        lbl.font = UIFont.systemFont(ofSize: UIFont.systemFontSize)
        lbl.textAlignment = .right
        lbl.numberOfLines = 0
        lbl.lineBreakMode = .byWordWrapping
        return lbl
    }()
    
    private let avatar : UIImageView = {
        let imgView = UIImageView()
        imgView.contentMode = .scaleAspectFit
        imgView.clipsToBounds = true
        return imgView
    }()
    
    
    override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
        super.init(style: style, reuseIdentifier: reuseIdentifier)

        
        let stretchingView = UIView()
        stretchingView.setContentHuggingPriority(UILayoutPriority(rawValue: 1), for: .horizontal)
        stretchingView.backgroundColor = .clear
        stretchingView.translatesAutoresizingMaskIntoConstraints = false
        
        let stackView = UIStackView(arrangedSubviews: [avatar, mentionNameLabel,stretchingView,mentionIdentityLabel])
        stackView.distribution = .fill
        stackView.axis = .horizontal
        stackView.spacing = 15
        stackView.alignment = .fill
        addSubview(stackView)
        avatar.anchor(top: nil, left: nil, bottom: nil, right: nil, paddingTop: 0, paddingLeft: 0, paddingBottom: 0, paddingRight: 0, width: 32.0, height: 32.0, enableInsets: false)

        stackView.anchor(top: topAnchor, left: leftAnchor, bottom: bottomAnchor, right: rightAnchor, paddingTop: 10, paddingLeft: 15, paddingBottom: 10, paddingRight: 15, width: 0, height: 0, enableInsets: false)
        
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}


extension UIView {
    
    func anchor (top: NSLayoutYAxisAnchor?, left: NSLayoutXAxisAnchor?, bottom: NSLayoutYAxisAnchor?, right: NSLayoutXAxisAnchor?, paddingTop: CGFloat, paddingLeft: CGFloat, paddingBottom: CGFloat, paddingRight: CGFloat, width: CGFloat, height: CGFloat, enableInsets: Bool) {
        var topInset = CGFloat(0)
        var bottomInset = CGFloat(0)
        
        if #available(iOS 11, *), enableInsets {
            let insets = self.safeAreaInsets
            topInset = insets.top
            bottomInset = insets.bottom
        }
        
        translatesAutoresizingMaskIntoConstraints = false
        
        if let top = top {
            self.topAnchor.constraint(equalTo: top, constant: paddingTop+topInset).isActive = true
        }
        if let left = left {
            self.leftAnchor.constraint(equalTo: left, constant: paddingLeft).isActive = true
        }
        if let right = right {
            rightAnchor.constraint(equalTo: right, constant: -paddingRight).isActive = true
        }
        if let bottom = bottom {
            bottomAnchor.constraint(equalTo: bottom, constant: -paddingBottom-bottomInset).isActive = true
        }
        if height != 0 {
            heightAnchor.constraint(equalToConstant: height).isActive = true
        }
        if width != 0 {
            widthAnchor.constraint(equalToConstant: width).isActive = true
        }
        
    }
    
}