//
//  QuoteGroupStorageManager.swift
//  Quote
//
//  Created by Torge Adelin on 24/06/2020.
//  Copyright © 2020 Torge Adelin. All rights reserved.
//

import Foundation
import CoreData
import UIKit

let quoteGroupStorageManager = QuoteGroupStorageManager()

class QuoteGroupStorageManager {
    let persistentContainer: NSPersistentContainer!
    
    //MARK: Init with dependency
    init(container: NSPersistentContainer) {
        self.persistentContainer = container
        self.persistentContainer.viewContext.automaticallyMergesChangesFromParent = true
    }
    
    convenience init() {
        // Use the default container for production environment
        guard let appDelegate = UIApplication.shared.delegate as? AppDelegate else {
            fatalError("Can not get shared app delegate")
        }
        self.init(container:appDelegate.persistentContainer)
    }
    
    lazy var backgroundContext: NSManagedObjectContext = {
        return self.persistentContainer.newBackgroundContext()
    }()
    
    func insertQuoteGroup(groupName: String, folderStyle: FolderStyle, folderIcon: String, dateCreated: Date, edit: Bool = false) -> QuoteGroup? {
        let currentQuoteGroups = fetch(with: groupName)
        if currentQuoteGroups.isEmpty {
            let newGroup = QuoteGroup(using: backgroundContext)
            newGroup.groupName = groupName
            newGroup.folderIcon = folderIcon
            newGroup.folderStyle = folderStyle.rawValue
            newGroup.dateCreated = dateCreated
            
            return newGroup
        } else {
            return nil
        }
    }
    
    func addQuoteToGroup(quoteID: String, quoteGroup: QuoteGroup) -> QuoteGroupItem? {
        let currentQuoteGroupItems = fetchQuoteItem(withID: quoteID, withQuoteGroup: quoteGroup)
        if currentQuoteGroupItems.isEmpty {
            let quoteItem = QuoteGroupItem(using: persistentContainer.viewContext)
            quoteItem.dateAdded = Date()
            quoteItem.quoteGroup = quoteGroup
            quoteItem.quoteID = quoteID
            
            try? persistentContainer.viewContext.save()
            
            return quoteItem
        } else {
            return nil
        }
    }
    
    func fetchQuoteItem(withID quoteID: String, withQuoteGroup quoteGroup: QuoteGroup) -> [QuoteGroupItem] {
        let context = persistentContainer.viewContext
        let fetchRequest = NSFetchRequest<QuoteGroupItem>(entityName: "QuoteGroupItem")
        
        let quoteIDPredicate = NSPredicate(format: "quoteID = %d", argumentArray: [quoteID])
        let quoteGroupPredicate = NSPredicate(format: "quoteGroup = %d", argumentArray: [quoteGroup])
        
        fetchRequest.predicate = NSCompoundPredicate(type: .and, subpredicates: [quoteIDPredicate,  quoteGroupPredicate])
        
        let result = try? context.fetch(fetchRequest)
        return result ?? [QuoteGroupItem]()
    }
    
    
    func fetch(with name: String) -> [QuoteGroup] {
        let context = persistentContainer.viewContext
        
        let fetchRequest = NSFetchRequest<QuoteGroup>(entityName: "QuoteGroup")
        
        fetchRequest.predicate = NSPredicate(format: "groupName = %d", argumentArray: [name])
        
        let result = try? context.fetch(fetchRequest)
        return result ?? [QuoteGroup]()
    }
    
    
    func fetchAll() -> [QuoteGroup] {
        let context = persistentContainer.viewContext
        
        let fetchRequest = NSFetchRequest<QuoteGroup>(entityName: "QuoteGroup")
        
        let result = try? context.fetch(fetchRequest)
        return result ?? [QuoteGroup]()
    }
    
    func editQuoteGroup(quoteGroup: QuoteGroup, newGroupName: String, newFolderIcon: String, newFolderStyle: FolderStyle) -> QuoteGroup? {
        let currentQuoteGroups = fetch(with: newGroupName)
        if currentQuoteGroups.isEmpty {
            quoteGroup.setValue(newGroupName, forKey: "groupName")
            quoteGroup.setValue(newFolderIcon, forKey: "folderIcon")
            quoteGroup.setValue(newFolderStyle.rawValue, forKey: "folderStyle")
            return quoteGroup
        } else {
            return nil
        }
        
    }
    
    // Remove a search term
    func remove(objectID: NSManagedObjectID ) {
        let obj = backgroundContext.object(with: objectID)
        backgroundContext.delete(obj)
    }
    
    func save() {
        if backgroundContext.hasChanges {
            do {
                try backgroundContext.save()
            } catch {
                print("Save error \(error)")
            }
        }
        
    }
    
}