LeStorage/LeStorage/StoredSingleton.swift

//
//  StoredObject.swift
//  LeStorage
//
//  Created by Laurent Morvillier on 03/05/2024.
//

import Foundation

/// A class extending the capabilities of StoredCollection but supposedly manages only one item
public class StoredSingleton<T: SyncedStorable>: SyncedCollection<T> {
    
    var shouldLoadDataFromServer: Bool = true
    
    init(store: Store, inMemory: Bool = false, shouldLoadDataFromServer: Bool = true) {
        super.init(store: store, inMemory: inMemory)
        self.shouldLoadDataFromServer = shouldLoadDataFromServer
    }
    
    public override func loadDataFromServerIfAllowed(clear: Bool = false) async throws {
        if shouldLoadDataFromServer {
            try await super.loadDataFromServerIfAllowed(clear: clear)
        }
    }
    
    /// Sets the singleton to the collection without synchronizing it
    public func setItemNoSync(_ instance: T) {
        self.collection.setSingletonNoSync(instance: instance)
    }
    
    /// updates the existing singleton
    public func update() {
        if let item = self.item() {
            self.addOrUpdate(instance: item)
        }
    }
    
    /// Returns the singleton
    public func item() -> T? {
        return self.collection.items.first
    }
    
    public func tryPutBeforeUpdating(_ instance: T) async throws {
        let result = try await StoreCenter.main.service().rawPut(instance)
        if let item = self.item() {
            item.copy(from: result)
            self.addOrUpdate(instance: item)
        }
    }
    
    // MARK: - Protects from use
    
    public override func addOrUpdate(contentOfs sequence: any Sequence<T>) {
        fatalError("method unavailable for StoredSingleton, use update")
    }
    
    func addOrUpdateIfNewer(_ instance: T) {
        fatalError("method unavailable for StoredSingleton, use update")
    }
    
}