//
//  SavedDataManager.swift
//  Tusker
//
//  Created by Shadowfacts on 12/19/19.
//  Copyright © 2019 Shadowfacts. All rights reserved.
//

import Foundation
import Pachyderm

class SavedDataManager: Codable {
    private(set) static var shared: SavedDataManager = load()
    
    private static var documentsDirectory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
    private static var archiveURL = SavedDataManager.documentsDirectory.appendingPathComponent("saved_data").appendingPathExtension("plist")
    
    static func save() {
        DispatchQueue.global(qos: .utility).async {
            let encoder = PropertyListEncoder()
            let data = try? encoder.encode(shared)
            try? data?.write(to: archiveURL, options: .noFileProtection)
        }
    }
    
    static func load() -> SavedDataManager {
        let decoder = PropertyListDecoder()
        if let data = try? Data(contentsOf: archiveURL),
            let savedHashtagsManager = try? decoder.decode(Self.self, from: data) {
            return savedHashtagsManager
        }
        return SavedDataManager()
    }
    
    private init() {}
    
    private var savedHashtags: [String: [Hashtag]] = [:] {
        didSet {
            SavedDataManager.save()
            NotificationCenter.default.post(name: .savedHashtagsChanged, object: nil)
        }
    }

    private var savedInstances: [String: [URL]] = [:] {
        didSet {
            SavedDataManager.save()
            NotificationCenter.default.post(name: .savedInstancesChanged, object: nil)
        }
    }
    
    func sortedHashtags(for account: LocalData.UserAccountInfo) -> [Hashtag] {
        if let hashtags = savedHashtags[account.id] {
            return hashtags.sorted(by: { $0.name < $1.name })
        } else {
            return []
        }
    }
    
    func isSaved(hashtag: Hashtag, for account: LocalData.UserAccountInfo) -> Bool {
        return savedHashtags[account.id]?.contains(hashtag) ?? false
    }
    
    func add(hashtag: Hashtag, for account: LocalData.UserAccountInfo) {
        if isSaved(hashtag: hashtag, for: account) {
            return
        }
        if var saved = savedHashtags[account.id] {
            saved.append(hashtag)
            savedHashtags[account.id] = saved
        } else {
            savedHashtags[account.id] = [hashtag]
        }
    }
    
    func remove(hashtag: Hashtag, for account: LocalData.UserAccountInfo) {
        guard isSaved(hashtag: hashtag, for: account) else { return }
        if var saved = savedHashtags[account.id] {
            saved.removeAll(where: { $0.name == hashtag.name })
            savedHashtags[account.id] = saved
        }
    }
    
    func savedInstances(for account: LocalData.UserAccountInfo) -> [URL] {
        return savedInstances[account.id] ?? []
    }
    
    func isSaved(instance url: URL, for account: LocalData.UserAccountInfo) -> Bool {
        return savedInstances[account.id]?.contains(url) ?? false
    }
    
    func add(instance url: URL, for account: LocalData.UserAccountInfo) {
        if isSaved(instance: url, for: account) { return }
        if var saved = savedInstances[account.id] {
            saved.append(url)
            savedInstances[account.id] = saved
        } else {
            savedInstances[account.id] = [url]
        }
    }
    
    func remove(instance url: URL, for account: LocalData.UserAccountInfo) {
        guard isSaved(instance: url, for: account) else { return }
        if var saved = savedInstances[account.id] {
            saved.removeAll(where: { $0 == url })
            savedInstances[account.id] = saved
        }
    }
}

extension Foundation.Notification.Name {
    static let savedHashtagsChanged = Notification.Name("savedHashtagsChanged")
    static let savedInstancesChanged = Notification.Name("savedInstancesChanged")
}