LeStorage/LeStorage/Storable.swift

//
//  Storable.swift
//  LeStorage
//
//  Created by Laurent Morvillier on 03/02/2024.
//

import Foundation

/// A protocol describing classes that can be stored locally in JSON and synchronized on our django server
public protocol Storable: Codable, Identifiable, NSObjectProtocol {
        
    /// The store containing a reference to the instance
    var store: Store? { get set }
    
    /// The resource name corresponding to the resource path on the API
    /// Also used as the name of the local file
    static func resourceName() -> String
    
    /// A method that deletes the local dependencies of the resource
    /// Mimics the behavior of the cascading delete on the django server
    /// Typically when we delete a resource, we automatically delete items that depends on it,
    /// so when we do that on the server, we also need to do it locally
    func deleteDependencies(store: Store, actionOption: ActionOption)
    
    /// A method that deletes dependencies of shared resources, but only if they are themselves shared
    /// and not referenced by other objects in the store
    /// This is used when cleaning up shared objects that are no longer in use
    func deleteUnusedSharedDependencies(store: Store)
    
    /// Copies the content of another item into the instance
    /// This behavior has been made to get live updates when looking at properties in SwiftUI screens
    func copy(from other: any Storable)

    /// This method returns RelationShips objects of the type
    static func relationships() -> [Relationship]
    static func parentRelationships() -> [Relationship]
    static func childrenRelationships() -> [Relationship]

    static func storeParent() -> Bool
    
}

extension Storable {
    
    /// Returns a filename for the class type
    static func fileName() -> String {
        return self.resourceName() + ".json"
    }
    
    /// Returns a string id for the instance
    public var stringId: String {
        switch self.id {
        case let sp as any StringProtocol:
            return String(sp)
        case let intLitteral as any ExpressibleByIntegerLiteral:
            return "\(intLitteral)"
        default:
            fatalError("id not convertible to string")
        }
    }
    
    /// Returns the relative path of the instance for the django server
    static func path(id: String? = nil) -> String {
        var path = self.resourceName() + "/"
        if let id {
            path.append(id)
            path.append("/")
        }
        return path
    }
    
    static func buildRealId(id: String) -> ID {
        switch ID.self {
        case is String.Type:
            return id as! ID
        case is Int64.Type:
            return Formatter.number.number(from: id)?.int64Value as! ID
        default:
            fatalError("ID \(type(of: ID.self)) is neither String nor Int, can't parse \(id)")
        }
    }
    
}