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

import Foundation

class DraftsManager: Codable, ObservableObject {

    private(set) static var shared: DraftsManager = load()
    
    private static var documentsDirectory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
    private static var archiveURL = DraftsManager.documentsDirectory.appendingPathComponent("drafts").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() -> DraftsManager {
        let decoder = PropertyListDecoder()
        if let data = try? Data(contentsOf: archiveURL),
            let draftsManager = try? decoder.decode(DraftsManager.self, from: data) {
            return draftsManager
        }
        return DraftsManager()
    }
    
    private init() {}
    
    required init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        
        if let dict = try? container.decode([UUID: Draft].self, forKey: .drafts) {
            self.drafts = dict
        } else if let array = try? container.decode([Draft].self, forKey: .drafts) {
            self.drafts = array.reduce(into: [:], { partialResult, draft in
                partialResult[draft.id] = draft
            })
        } else {
            throw DecodingError.dataCorruptedError(forKey: .drafts, in: container, debugDescription: "expected drafts to be a dict or array of drafts")
        }
    }
    
    func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
        try container.encode(drafts, forKey: .drafts)
    }
    
    @Published private var drafts: [UUID: Draft] = [:]
    var sorted: [Draft] {
        return drafts.values.sorted(by: { $0.lastModified > $1.lastModified })
    }
    
    func add(_ draft: Draft) {
        drafts[draft.id] = draft
    }
    
    func remove(_ draft: Draft) {
        drafts.removeValue(forKey: draft.id)
    }
    
    func getBy(id: UUID) -> Draft? {
        return drafts[id]
    }
    
    enum CodingKeys: String, CodingKey {
        case drafts
    }
    
}