import RealmSwift

internal struct RealmService {

    internal static let shared = RealmService()
    private let realm = try! Realm()

    // MARK: - Setter
    internal func add<T: Object>(object: T) {
        do {
            try realm.write({
                realm.add(object)
            })
        } catch {
            printError()
        }
    }

    internal func add<T: Object>(array: [T]) {
        do {
            try realm.write({
                realm.add(array)
            })
        } catch {
            printError()
        }
    }

    // MARK: - Getter
    internal func get<T: Object>(objectsOfInstanceType instanceType: T.Type) -> Results<T>? {
        let objects = realm.objects(instanceType)
        if !objects.isEmpty {
            return objects
        }
        return nil
    }

    internal func get<T: Object>(objectsOfInstanceType instanceType: T.Type, withPredicate predicate: NSPredicate) -> Results<T>? {
        if let objects = get(objectsOfInstanceType: instanceType) {
            let filteredObjects = objects.filter(predicate)
            if !filteredObjects.isEmpty {
                return filteredObjects
            }
        }
        return nil
    }

    internal func get<T: Object>(arrayOfInstanceType instanceType: T.Type) -> [T]? {
        if let objects = get(objectsOfInstanceType: instanceType) {
            return objects.toArray()
        }
        return nil
    }

    internal func get<T: Object>(arrayOfInstanceType instanceType: T.Type, withPredicate predicate: NSPredicate) -> [T]? {
        if let objects = get(objectsOfInstanceType: instanceType, withPredicate: predicate) {
            return objects.toArray()
        }
        return nil
    }

    // MARK: - Remove
    internal func remove<T: Object>(object: T) {
        realm.beginWrite()
        realm.delete(object)
        do {
            try realm.commitWrite()
        } catch {
            printError()
        }
    }

    internal func remove<T: Object>(objectsOfInstanceType instanceType: T.Type) {
        let objects = realm.objects(instanceType)
        realm.beginWrite()
        realm.delete(objects)
        do {
            try realm.commitWrite()
        } catch {
            printError()
        }
    }

    // MARK: - Helpers
    internal func exists<T: Object>(objectsOfInstanceType instanceType: T.Type, withPredicate predicate: NSPredicate) -> Bool {
        if let _ = get(objectsOfInstanceType: instanceType, withPredicate: predicate) {
            return true
        } else {
            return false
        }
    }

    private func printError() {
        print("Realm Error")
    }

}