//
//  ProfileHeaderView.swift
//  Tusker
//
//  Created by Shadowfacts on 7/4/20.
//  Copyright © 2020 Shadowfacts. All rights reserved.
//

import UIKit
import Pachyderm
import Combine

protocol ProfileHeaderViewDelegate: TuskerNavigationDelegate {
    func profileHeader(_ headerView: ProfileHeaderView, selectedPostsIndexChangedTo newIndex: Int)
}

class ProfileHeaderView: UIView {
    
    static func create() -> ProfileHeaderView {
        let nib = UINib(nibName: "ProfileHeaderView", bundle: .main)
        return nib.instantiate(withOwner: nil, options: nil).first as! ProfileHeaderView
    }
    
    weak var delegate: ProfileHeaderViewDelegate? {
        didSet {
            createObservers()
        }
    }
    var mastodonController: MastodonController! { delegate?.apiController }

    @IBOutlet weak var headerImageView: UIImageView!
    @IBOutlet weak var avatarContainerView: UIView!
    @IBOutlet weak var avatarImageView: UIImageView!
    @IBOutlet weak var moreButton: VisualEffectImageButton!
    @IBOutlet weak var displayNameLabel: EmojiLabel!
    @IBOutlet weak var usernameLabel: UILabel!
    @IBOutlet weak var followsYouLabel: UILabel!
    @IBOutlet weak var noteTextView: StatusContentTextView!
    @IBOutlet weak var fieldsStackView: UIStackView!
    @IBOutlet weak var fieldNamesStackView: UIStackView!
    @IBOutlet weak var fieldValuesStackView: UIStackView!
    @IBOutlet weak var pagesSegmentedControl: UISegmentedControl!
    
    var accountID: String!
    
    private var avatarRequest: ImageCache.Request?
    private var headerRequest: ImageCache.Request?
    
    private var isGrayscale = false
    
    private var cancellables = [AnyCancellable]()
    
    deinit {
        avatarRequest?.cancel()
        headerRequest?.cancel()
    }
    
    override func awakeFromNib() {
        super.awakeFromNib()
        
        avatarContainerView.layer.masksToBounds = true
        avatarImageView.layer.masksToBounds = true
        avatarImageView.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(avatarPressed)))
        avatarImageView.isUserInteractionEnabled = true
        
        headerImageView.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(headerPressed)))
        headerImageView.isUserInteractionEnabled = true
        
        moreButton.layer.cornerRadius = 16
        moreButton.layer.masksToBounds = true
        
        NotificationCenter.default.addObserver(self, selector: #selector(updateUIForPreferences), name: .preferencesChanged, object: nil)
        
        moreButton.addInteraction(UIPointerInteraction(delegate: self))
        moreButton.showsMenuAsPrimaryAction = true
        moreButton.isContextMenuInteractionEnabled = true
    }
    
    private func createObservers() {
        cancellables = []
        
        mastodonController.persistentContainer.accountSubject
            .filter { [weak self] in $0 == self?.accountID }
            .receive(on: DispatchQueue.main)
            .sink { [weak self] in self?.updateUI(for: $0) }
            .store(in: &cancellables)
        
        mastodonController.persistentContainer.relationshipSubject
            .filter { [weak self] in $0 == self?.accountID }
            .receive(on: DispatchQueue.main)
            .sink { [weak self] (_) in self?.updateRelationship() }
            .store(in: &cancellables)
    }
    
    func updateUI(for accountID: String) {
        self.accountID = accountID
        
        guard let mastodonController = mastodonController else { return }
        guard let account = mastodonController.persistentContainer.account(for: accountID) else {
            fatalError("Missing cached account \(accountID)")
        }
        
        updateUIForPreferences()
        
        usernameLabel.text = "@\(account.acct)"
        
        updateImages(account: account)
        
        moreButton.menu = UIMenu(title: "", image: nil, identifier: nil, options: [], children: actionsForProfile(accountID: accountID, sourceView: moreButton))
        
        noteTextView.navigationDelegate = delegate
        noteTextView.setTextFromHtml(account.note)
        noteTextView.setEmojis(account.emojis)
        
        // don't show relationship label for the user's own account
        if accountID != mastodonController.account?.id {
            // while fetching the most up-to-date, show the current data (if any)
            updateRelationship()
            
            let request = Client.getRelationships(accounts: [accountID])
            mastodonController.run(request) { [weak self] (response) in
                guard let self = self,
                      case let .success(results, _) = response,
                      let relationship = results.first else {
                    return
                }
                self.mastodonController.persistentContainer.addOrUpdate(relationship: relationship)
            }
        }
        
        fieldsStackView.isHidden = account.fields.isEmpty
        
        fieldNamesStackView.arrangedSubviews.forEach { $0.removeFromSuperview() }
        fieldValuesStackView.arrangedSubviews.forEach { $0.removeFromSuperview() }
        var fieldAccessibilityElements = [Any]()
        for field in account.fields {
            let nameLabel = EmojiLabel()
            nameLabel.text = field.name
            nameLabel.font = .boldSystemFont(ofSize: 17)
            nameLabel.textAlignment = .right
            nameLabel.numberOfLines = 0
            nameLabel.lineBreakMode = .byWordWrapping
            nameLabel.setContentCompressionResistancePriority(.defaultLow, for: .horizontal)
            nameLabel.setEmojis(account.emojis, identifier: "")
            fieldNamesStackView.addArrangedSubview(nameLabel)
            
            let valueTextView = ContentTextView()
            valueTextView.isSelectable = false
            valueTextView.font = .systemFont(ofSize: 17)
            valueTextView.setTextFromHtml(field.value)
            valueTextView.setEmojis(account.emojis)
            valueTextView.textAlignment = .left
            valueTextView.awakeFromNib()
            valueTextView.navigationDelegate = delegate
            valueTextView.setContentCompressionResistancePriority(.defaultLow, for: .horizontal)
            fieldValuesStackView.addArrangedSubview(valueTextView)
            
            nameLabel.heightAnchor.constraint(equalTo: valueTextView.heightAnchor).isActive = true
            fieldAccessibilityElements.append(nameLabel)
            fieldAccessibilityElements.append(valueTextView)
        }
        
        accessibilityElements = [
            displayNameLabel!,
            usernameLabel!,
            noteTextView!,
        ] + fieldAccessibilityElements + [
            moreButton!,
            pagesSegmentedControl!,
        ]
    }
    
    private func updateRelationship() {
        guard let relationship = mastodonController.persistentContainer.relationship(forAccount: accountID) else {
            return
        }
        
        followsYouLabel.isHidden = !relationship.followedBy
    }
    
    @objc private func updateUIForPreferences() {
        guard let account = mastodonController.persistentContainer.account(for: accountID) else {
            fatalError("Missing cached account \(accountID!)")
        }
        
        avatarContainerView.layer.cornerRadius = Preferences.shared.avatarStyle.cornerRadius(for: avatarContainerView)
        avatarImageView.layer.cornerRadius = Preferences.shared.avatarStyle.cornerRadius(for: avatarImageView)
        displayNameLabel.updateForAccountDisplayName(account: account)
        
        if isGrayscale != Preferences.shared.grayscaleImages {
            updateImages(account: account)
        }
    }
    
    private func updateImages(account: AccountMO) {
        isGrayscale = Preferences.shared.grayscaleImages
        
        let accountID = account.id
        let avatarURL = account.avatar
        // always load original for avatars, because ImageCache.avatars stores them scaled-down in memory
        avatarRequest = ImageCache.avatars.get(avatarURL, loadOriginal: true) { [weak self] (_, image) in
            guard let self = self,
                  let image = image,
                  self.accountID == accountID,
                  let transformedImage = ImageGrayscalifier.convertIfNecessary(url: avatarURL, image: image) else {
                return
            }
            self.avatarRequest = nil
            
            DispatchQueue.main.async {
                self.avatarImageView.image = transformedImage
            }
        }
        if let header = account.header {
            headerRequest = ImageCache.headers.get(header) { [weak self] (_, image) in
                guard let self = self,
                      let image = image,
                      self.accountID == accountID,
                      let transformedImage = ImageGrayscalifier.convertIfNecessary(url: header, image: image) else {
                    return
                }
                self.headerRequest = nil
                
                DispatchQueue.main.async {
                    self.headerImageView.image = transformedImage
                }
            }
        }
    }
    
    // MARK: Interaction
    
    @objc func avatarPressed() {
        guard let account = mastodonController.persistentContainer.account(for: accountID) else {
            return
        }
        delegate?.showLoadingLargeImage(url: account.avatar, cache: .avatars, description: nil, animatingFrom: avatarImageView)
    }
    
    @objc func headerPressed() {
        guard let account = mastodonController.persistentContainer.account(for: accountID),
              let header = account.header else {
            return
        }
        delegate?.showLoadingLargeImage(url: header, cache: .headers, description: nil, animatingFrom: headerImageView)
    }
    
    @IBAction func postsSegmentedControlChanged(_ sender: UISegmentedControl) {
        delegate?.profileHeader(self, selectedPostsIndexChangedTo: sender.selectedSegmentIndex)
    }
    
}

extension ProfileHeaderView: UIPointerInteractionDelegate {
    func pointerInteraction(_ interaction: UIPointerInteraction, styleFor region: UIPointerRegion) -> UIPointerStyle? {
        let preview = UITargetedPreview(view: moreButton)
        return UIPointerStyle(effect: .lift(preview), shape: .none)
    }
}

extension ProfileHeaderView: MenuPreviewProvider {
    var navigationDelegate: TuskerNavigationDelegate? { delegate }
}