//
//  DraftsTableViewController.swift
//  Tusker
//
//  Created by Shadowfacts on 10/22/18.
//  Copyright © 2018 Shadowfacts. All rights reserved.
//

import UIKit

protocol DraftsTableViewControllerDelegate: AnyObject {
    func draftSelectionCanceled()
    func shouldSelectDraft(_ draft: Draft, completion: @escaping (Bool) -> Void)
    func draftSelected(_ draft: Draft)
    func draftSelectionCompleted()
}

class DraftsTableViewController: UITableViewController {
    
    let account: LocalData.UserAccountInfo
    let excludedDraft: Draft?
    weak var delegate: DraftsTableViewControllerDelegate?
    
    var drafts = [Draft]()
    
    init(account: LocalData.UserAccountInfo, exclude: Draft? = nil) {
        self.account = account
        self.excludedDraft = exclude
        
        super.init(nibName: "DraftsTableViewController", bundle: nil)
        
        title = "Drafts"
        navigationItem.leftBarButtonItem = UIBarButtonItem(barButtonSystemItem: .cancel, target: self, action: #selector(cancelPressed))
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        tableView.rowHeight = UITableView.automaticDimension
        tableView.estimatedRowHeight = 140
        
        tableView.register(UINib(nibName: "DraftTableViewCell", bundle: nil), forCellReuseIdentifier: "draftCell")
        
        tableView.dragDelegate = self
        
        drafts = DraftsManager.shared.sorted.filter { (draft) in
            draft.accountID == account.id && draft != excludedDraft
        }
    }
    
    func draft(for indexPath: IndexPath) -> Draft {
        return drafts[indexPath.row]
    }
    
    // MARK: - Table View Data Source
    
    override func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }
    
    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return drafts.count
    }
    
    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        guard let cell = tableView.dequeueReusableCell(withIdentifier: "draftCell", for: indexPath) as? DraftTableViewCell else { fatalError() }
        
        cell.updateUI(for: draft(for: indexPath))
        
        return cell
    }
    
    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        let draft = self.draft(for: indexPath)
        func select() {
            delegate?.draftSelected(draft)
            dismiss(animated: true) {
                self.delegate?.draftSelectionCompleted()
            }
        }
        if let delegate = delegate {
            delegate.shouldSelectDraft(draft) { (shouldSelect) in
                if shouldSelect {
                    select()
                } else {
                    tableView.selectRow(at: nil, animated: true, scrollPosition: .none)
                }
            }
        } else {
            select()
        }
    }
    
    override func tableView(_ tableView: UITableView, editingStyleForRowAt indexPath: IndexPath) -> UITableViewCell.EditingStyle {
        return .delete
    }
    
    override func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool {
        return true
    }
    
    override func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCell.EditingStyle, forRowAt indexPath: IndexPath) {
        guard editingStyle == .delete else { return }
        DraftsManager.shared.remove(draft(for: indexPath))
        drafts.remove(at: indexPath.row)
        tableView.deleteRows(at: [indexPath], with: .automatic)
    }
    
    // MARK: - Interaction
    
    @objc func cancelPressed() {
        delegate?.draftSelectionCanceled()
        dismiss(animated: true)
    }
    
}

extension DraftsTableViewController: UITableViewDragDelegate {
    func tableView(_ tableView: UITableView, itemsForBeginning session: UIDragSession, at indexPath: IndexPath) -> [UIDragItem] {
        let draft = self.draft(for: indexPath)
        let activity = UserActivityManager.editDraftActivity(id: draft.id, accountID: account.id)
        let provider = NSItemProvider(object: activity)
        return [UIDragItem(itemProvider: provider)]
    }
}