//
//  ComposeViewController.swift
//  Tusker
//
//  Created by Shadowfacts on 8/28/18.
//  Copyright © 2018 Shadowfacts. All rights reserved.
//

import UIKit
import Pachyderm
import Intents

class ComposeViewController: UIViewController {
    
    let router: AppRouter
    
    @IBOutlet weak var scrollView: UIScrollView!
    @IBOutlet weak var inReplyToContainerView: UIView!
    @IBOutlet weak var inReplyToAvatarImageView: UIImageView!
    @IBOutlet weak var inReplyToDisplayNameLabel: UILabel!
    @IBOutlet weak var inReplyToUsernameLabel: UILabel!
    @IBOutlet weak var inReplyToContentLabel: StatusContentLabel!
    @IBOutlet weak var inReplyToLabel: UILabel!
    @IBOutlet weak var statusTextView: UITextView!
    @IBOutlet weak var placeholderLabel: UILabel!
    @IBOutlet weak var charactersRemainingLabel: UILabel!
    @IBOutlet weak var visibilityButton: UIButton!
    @IBOutlet weak var postButton: UIButton!
    @IBOutlet weak var contentWarningTextField: UITextField!
    @IBOutlet weak var mediaStackView: UIStackView!
    @IBOutlet weak var paddingView: UIView!
    @IBOutlet weak var progressView: SteppedProgressView!
    
    var scrolled = false
    
    var inReplyToID: String?
    
    // TODO: cleanup this
    var mentioningAcct: String?
    var text: String?
    var initialText: String?
    
    var draft: DraftsManager.Draft?
    
    // Weak so that if a new session is initiated (i.e. XCBManager.currentSession is changed) while the current one is in progress, this one will be released
    weak var xcbSession: XCBSession?
    
    var contentWarning = false {
        didSet {
            contentWarningTextField.isHidden = !contentWarning
        }
    }
    var visibility = Preferences.shared.defaultPostVisibility {
        didSet {
            visibilityButton.setTitle(visibility.displayName, for: .normal)
        }
    }
    
    var status: Status?
    
    init(inReplyTo inReplyToID: String? = nil, mentioningAcct: String? = nil, text: String? = nil, router: AppRouter) {
        self.inReplyToID = inReplyToID
        self.mentioningAcct = mentioningAcct
        self.text = text
        self.router = router
        
        super.init(nibName: "ComposeViewController", bundle: nil)
        
        navigationItem.leftBarButtonItem = UIBarButtonItem(barButtonSystemItem: .cancel, target: self, action: #selector(cancelPressed))
        navigationItem.rightBarButtonItem = UIBarButtonItem(title: "Drafts", style: .plain, target: self, action: #selector(draftsPressed))
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()

        statusTextView.layer.cornerRadius = 5
        statusTextView.layer.masksToBounds = true
        statusTextView.delegate = self
        visibilityButton.setTitle(visibility.displayName, for: .normal)
        contentWarningTextField.delegate = self
        
        let toolbar = UIToolbar(frame: CGRect(x: 0, y: 0, width: view.frame.width, height: 30))
        let flexSpace = UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: nil, action: nil)
        let done = UIBarButtonItem(barButtonSystemItem: .done, target: self, action: #selector(keyboardDoneButtonPressed))
        toolbar.setItems([flexSpace, done], animated: false)
        toolbar.sizeToFit()
        statusTextView.inputAccessoryView = toolbar
        
        if let inReplyToID = inReplyToID,
            let inReplyTo = MastodonCache.status(for: inReplyToID) {
            inReplyToDisplayNameLabel.text = inReplyTo.account.realDisplayName
            inReplyToUsernameLabel.text = "@\(inReplyTo.account.username)"
            inReplyToContentLabel.statusID = inReplyToID
            inReplyToAvatarImageView.layer.cornerRadius = Preferences.shared.avatarStyle.cornerRadius(for: inReplyToAvatarImageView)
            inReplyToAvatarImageView.layer.masksToBounds = true
            inReplyToAvatarImageView.image = nil
            ImageCache.avatars.get(inReplyTo.account.avatar) { (data) in
                guard let data = data else { return }
                DispatchQueue.main.async {
                    self.inReplyToAvatarImageView.image = UIImage(data: data)
                }
            }
            inReplyToLabel.text = "In reply to \(inReplyTo.account.realDisplayName)"
            if inReplyTo.account != MastodonController.account {
                statusTextView.text = "@\(inReplyTo.account.acct) "
            }
            statusTextView.text += inReplyTo.mentions.filter({ $0.id != MastodonController.account.id }).map({ "@\($0.acct) " }).joined()
            contentWarning = inReplyTo.sensitive
            contentWarningTextField.text = inReplyTo.spoilerText
            visibility = inReplyTo.visibility
        } else {
            inReplyToLabel.isHidden = true
            inReplyToContainerView.isHidden = true
        }
        
        if let mentioningAcct = mentioningAcct {
            statusTextView.text += "@\(mentioningAcct) "
        }
        if let text = text {
            statusTextView.text += text
        }
        
        initialText = statusTextView.text.trimmingCharacters(in: .whitespacesAndNewlines)
        
        updateCharactersRemaining()
        updatePlaceholder()
        
        progressView.progress = 0
        
        if let mentioningAcct = mentioningAcct {
            let req = MastodonController.client.searchForAccount(query: mentioningAcct)
            MastodonController.client.run(req) { [weak self] (response) in
                if case let .success(accounts, _) = response {
                    self?.userActivity = UserActivityManager.newPostActivity(mentioning: accounts.first)
                } else {
                    self?.userActivity = UserActivityManager.newPostActivity()
                }
            }
        } else {
            self.userActivity = UserActivityManager.newPostActivity()
        }
        
    }
    
    override func viewDidLayoutSubviews() {
        if inReplyToID != nil && !scrolled {
            scrollView.contentOffset = CGPoint(x: 0, y: inReplyToContainerView.bounds.height - 44)
            scrolled = true
        }
    }

    func addMedia(for image: UIImage) {
        let mediaView = ComposeMediaView(image: image)
        mediaView.delegate = self
        mediaStackView.addArrangedSubview(mediaView)
    }
    
    func updateCharactersRemaining() {
        let count = CharacterCounter.count(text: statusTextView.text)
        let remaining = (MastodonController.instance.maxStatusCharacters ?? 500) - count
        if remaining < 0 {
            charactersRemainingLabel.textColor = .red
            postButton.isEnabled = false
        } else {
            charactersRemainingLabel.textColor = .darkGray
            postButton.isEnabled = true
        }
        charactersRemainingLabel.text = remaining.description
    }
    
    func updatePlaceholder() {
        placeholderLabel.isHidden = !statusTextView.text.isEmpty
    }
    
    // MARK: - Navigation
    
    override func dismiss(animated flag: Bool, completion: (() -> Void)? = nil) {
        statusTextView.resignFirstResponder()
        contentWarningTextField.resignFirstResponder()
        super.dismiss(animated: flag, completion: completion)
    }
    
    // MARK: - Interaction

    @IBAction func visibilityPressed(_ sender: Any) {
        let alertController = UIAlertController(currentVisibility: self.visibility) { (visibility) in
            guard let visibility = visibility else { return }
            UIView.performWithoutAnimation {
                self.visibility = visibility
                self.visibilityButton.layoutIfNeeded()
            }
        }
        present(alertController, animated: true)
    }
    
    @IBAction func contentWarningPressed(_ sender: Any) {
        contentWarning = !contentWarning
    }
    
    @IBAction func mediaPressed(_ sender: Any) {
        let imagePicker = UIImagePickerController()
        imagePicker.delegate = self
        
        let alertController = UIAlertController(title: "Choose Image Source", message: nil, preferredStyle: .actionSheet)
        if UIImagePickerController.isSourceTypeAvailable(.camera) {
            alertController.addAction(UIAlertAction(title: "Camera", style: .default, handler: { _ in
                imagePicker.sourceType = .camera
                self.present(imagePicker, animated: true)
            }))
        }
        if UIImagePickerController.isSourceTypeAvailable(.photoLibrary) {
            alertController.addAction(UIAlertAction(title: "Photo Library", style: .default, handler: { __ in
                imagePicker.sourceType = .photoLibrary
                self.present(imagePicker, animated: true)
            }))
        }
        alertController.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: nil))
        present(alertController, animated: true)
    }
    
    @IBAction func postPressed(_ sender: Any) {
        guard let text = statusTextView.text,
            !text.isEmpty else { return }
        
        postButton.isEnabled = false
        
        let contentWarning: String?
        if self.contentWarning,
            let text = contentWarningTextField.text,
            !text.isEmpty {
            contentWarning = text
        } else {
            contentWarning = nil
        }
        let sensitive = contentWarning != nil
        
        let visibility = self.visibility
        
        var attachments: [Attachment?] = []
        let group = DispatchGroup()
        for view in mediaStackView.arrangedSubviews {
            guard let mediaView = view as? ComposeMediaView,
                let image = mediaView.image,
                let data = image.pngData() else { continue }
            let index = attachments.count
            attachments.append(nil)
            progressView.steps += 1
            group.enter()
            let request = MastodonController.client.upload(attachment: FormAttachment(pngData: data), description: mediaView.mediaDescription)
            MastodonController.client.run(request) { response in
                guard case let .success(attachment, _) = response else { fatalError() }
                attachments[index] = attachment
                self.progressView.step()
                group.leave()
            }
        }
        
        progressView.steps = 2 + attachments.count
        progressView.currentStep = 1
        
        group.notify(queue: .main) {
            let attachments = attachments.compactMap { $0 }
            
            let request = MastodonController.client.createStatus(text: text,
                                                                        inReplyTo: self.inReplyToID,
                                                                        media: attachments,
                                                                        sensitive: sensitive,
                                                                        spoilerText: contentWarning,
                                                                        visibility: visibility)
            MastodonController.client.run(request) { response in
                guard case let .success(status, _) = response else { fatalError() }
                self.status = status
                MastodonCache.add(status: status)
                
                if let draft = self.draft {
                    DraftsManager.shared.remove(draft)
                }
                
                DispatchQueue.main.async {
                    self.progressView.step()
                    self.dismiss(animated: true)
                    // TODO: reorganize routing/navigation
                    (((self.presentingViewController as! MainTabBarViewController).selectedViewController as! UINavigationController).topViewController as! TuskerNavigationDelegate).selected(status: status.id)
                    
                    self.xcbSession?.complete(with: .success, additionalData: [
                        "statusURL": status.url?.absoluteString,
                        "statusURI": status.uri
                        ])
                }
            }
        }
    }
    
    @objc func imagePressed(_ gesture: UITapGestureRecognizer) {
        gesture.view!.superview!.removeFromSuperview()
    }
    
    @objc func keyboardDoneButtonPressed() {
        statusTextView.endEditing(false)
    }
    
    func saveDraft() {
        if let draft = draft {
            draft.update(text: statusTextView.text)
        } else {
            DraftsManager.shared.create(text: statusTextView.text)
        }
    }
    
    func close() {
        dismiss(animated: true)
        xcbSession?.complete(with: .cancel)
    }
    
    @objc func cancelPressed() {
        guard statusTextView.text.trimmingCharacters(in: .whitespacesAndNewlines) != initialText else {
            close()
            return
        }
        
        if Preferences.shared.automaticallySaveDrafts {
            saveDraft()
            close()
            return
        }
        
        let alert = UIAlertController(title: nil, message: nil, preferredStyle: .actionSheet)
        alert.addAction(UIAlertAction(title: "Save draft", style: .default, handler: { (_) in
            self.saveDraft()
            self.close()
        }))
        alert.addAction(UIAlertAction(title: "Delete draft", style: .destructive, handler: { (_) in
            if let draft = self.draft {
                DraftsManager.shared.remove(draft)
            }
            self.close()
        }))
        alert.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: { (_) in
        }))
        router.present(alert, animated: true)
    }
    
    @objc func draftsPressed() {
        let drafts = router.drafts()
        drafts.delegate = self
        router.present(UINavigationController(rootViewController: drafts), animated: true)
    }
    
}

extension ComposeViewController: UITextFieldDelegate {
    func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        textField.endEditing(false)
        return true
    }
}

extension ComposeViewController: UITextViewDelegate {
    func textViewDidChange(_ textView: UITextView) {
        updateCharactersRemaining()
        updatePlaceholder()
    }
}

extension ComposeViewController: UIImagePickerControllerDelegate, UINavigationControllerDelegate {
    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
        if let selectedImage = info[.originalImage] as? UIImage {
            addMedia(for: selectedImage)
            dismiss(animated: true)
        }
    }
}

extension ComposeViewController: ComposeMediaViewDelegate {
    func editDescription(for media: ComposeMediaView) {
        let alertController = UIAlertController(title: "Media Description", message: nil, preferredStyle: .alert)
        alertController.addTextField { textField in
            textField.text = media.mediaDescription
        }
        alertController.addAction(UIAlertAction(title: "Confirm", style: .default, handler: { _ in
            let description = alertController.textFields![0].text
            media.mediaDescription = description
        }))
        alertController.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: nil))
        present(alertController, animated: true)
    }
}

extension ComposeViewController: DraftsTableViewControllerDelegate {
    func draftSelectionCanceled() {
    }
    
    func draftSelected(_ draft: DraftsManager.Draft) {
        self.draft = draft
        statusTextView.text = draft.text
        updatePlaceholder()
    }
}