using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;
using CarManagerV3.Classes;
using CarManagerV3.Manager;

namespace CarManagerV3
{
    // Could be made non-static / non-singleton if multiple collections are needed in the future. Not likely though.
    /// <summary>
    /// The <c>StateManager</c> class is responsible for managing the state of the car collection, including adding, removing, updating, and retrieving cars.
    /// Fully static / singleton at the moment, as only one collection is needed.
    /// </summary>
    internal class StateManager
    {
        // Initialize global static list of cars
        static List<Car> cars = new List<Car>();
        // Initialize default file path for car data.
        static string filePath = "";

        static bool hasConfirmedMigration = false;



        /// <summary>
        /// Gets a car by its identifier.
        /// </summary>
        /// <param name="id">The identifier.</param>
        /// <returns>
        /// A <see cref="Car"/> object if found; otherwise, null.
        /// </returns>
        public static Car GetCarById(string id)
        {
            cars = SafeManager.ReadCars(filePath);
            return cars.FirstOrDefault(c => c.Id == id);
        }

        /// <summary>
        /// Public getter and setter for the cars list. Used to have better control over the list.
        /// </summary>
        /// <value>
        /// The cars.
        /// </value>
        public static List<Car> Cars { get { return cars; } set { cars = value; } }

        /// <summary>
        /// Adds a car to the collection.
        /// </summary>
        /// <param name="car">The <see cref="Car"/> to add.</param>
        public static void AddCar(Car car)
        {
            cars = SafeManager.ReadCars(filePath);
            cars.Add(car);
            SafeManager.SaveCars(filePath, cars);
        }

        /// <summary>
        /// Removes a car from the collection.
        /// </summary>
        /// <param name="car">The <see cref="Car"/> to remove.</param>
        public static void RemoveCar(Car car)
        {
            cars = SafeManager.ReadCars(filePath);
            Car existingCar = GetCarById(car.Id);
            if (existingCar == null) return;
            cars.Remove(existingCar);
            SafeManager.SaveCars(filePath, cars);
        }

        /// <summary>
        /// Updates a car in the collection. Identifies itself by its Id.
        /// </summary>
        /// <remarks>
        /// If the car's Id has changed during editing, this will not work correctly. Keep Id immutable!
        /// </remarks>
        /// <param name="car">The <see cref="Car"/> to update.</param>
        public static void UpdateCar(Car car)
        {
            Car existingCar = GetCarById(car.Id);
            if (existingCar != null)
            {
                int index = cars.IndexOf(existingCar);
                cars[index] = car;
                Console.WriteLine("Updated car: " + existingCar.Id);
                SafeManager.SaveCars(filePath, cars);
            }
        }

        /// <summary>
        /// Creates a new car and adds it to the collection.
        /// </summary>
        /// <param name="make">The make.</param>
        /// <param name="model">The model.</param>
        /// <param name="year">The year.</param>
        /// <param name="color">The color.</param>
        /// <param name="mileage">The mileage.</param>
        /// <param name="price">The price.</param>
        /// <returns>
        /// The newly created <see cref="Car"/> object.
        /// </returns>
        public static Car CreateCar(string make, string model, int year, string color, int mileage, decimal price)
        {
            cars = SafeManager.ReadCars(filePath);
            int newOrder = cars.Count > 0 ? cars.Max(c => c.Order) + 1 : 1;
            Car newCar = new Car("", make, model, year, color, mileage, price, newOrder);
            AddCar(newCar);
            return newCar;
        }

        /// <summary>
        /// Sets the file path used for saving and loading car data.
        /// Called when user selects a new file path.
        /// </summary>
        /// <param name="path">The path.</param>
        public static void setFilePath(string path)
        {
            // Reset migration confirmation when changing file path, as the new file may also require migration.
            hasConfirmedMigration = false;
            filePath = path;
        }

        /// <summary>
        /// Normalizes the orders of the cars in the collection to be sequential starting from 1, while keeping the relative order the same.
        /// </summary>
        /// <param name="cars">The list of <see cref="Car"/>s.</param>
        /// <returns>A normalized List of <see cref="Car"/>s </returns>
        public static List<Car> normalizeOrders(List<Car> cars)
        {
            // Normalize the Order field of all cars to be sequential starting from 1, while keeping the relative order the same.
            var orderedCars = cars.OrderBy(c => c.Order).ToList();
            for (int i = 0; i < orderedCars.Count; i++)
            {
                orderedCars[i].Order = i + 1;
            }
            return orderedCars;
        }

        /// <summary>
        /// Prompts the user to confirm migration if they haven't already confirmed it for the current session. 
        /// This is to prevent multiple annoying popups if the user tries to open multiple files that require migration.
        /// </summary>
        /// <returns>True if the user has accepted to migrate the file, otherwise False</returns>
        public static bool askForMigration(FileMeta meta = null)
        {
            if (hasConfirmedMigration)
            {
                return true;
            }
            string promptMessage = "The file you are trying to open is in an older format. Do you want to attempt to migrate it to the new format? If you choose not to migrate, the file will not be opened.";
            if(meta != null)
            {
                int nUpdatesNeeded = FileUpdate.GetRequiredUpdates(meta.Version).Count;
                promptMessage = $"The file you are trying to open is in an older format ({meta.Version}). It requires {nUpdatesNeeded} update(s) to be migrated to your Version ({Updater.GetCurrentVersion(true)}).\nDo you want to attempt to migrate it? If you choose not to migrate, the file will not be opened.";
            }
            DialogResult result = MessageBox.Show(promptMessage, "Migration Needed", MessageBoxButtons.YesNo, MessageBoxIcon.Warning);
            hasConfirmedMigration = result == DialogResult.Yes;
            return hasConfirmedMigration;
        }

    }
}