//using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;

namespace MovieDatabase.Models
{
    public class Database
    {
        private List<Movie> db; // list of movies in the database
        private int _index; // position of current movie in the database

        // initialise the database properties
        public Database()
        {

        }

        // A property to Return number of movies in the database
        public int Count
        {
            // get will return Count
            get
            {
                return Count;
            }

            // set Count to size of database (amount of movies)
            set
            {
                Count = db.Count;
            }
        }

        // A property to return  current _index position which should be either
        // -1 if database is empty
        // 0 - db.Count-1 if database is not empty
        public int Index
        {
            get
            {
                return _index;
            }

            set
            {
                if (!db.Any())
                {
                    int temp_IndexVal;
                    temp_IndexVal = _index;

                    _index = (db.Count - 1);

                    // set _index to first element
                    if (value == 0)
                        _index = 0;

                    // set _index to next element
                    if (value == -2)
                        _index = temp_IndexVal++;

                    // set _index to previous element
                    if (value == -3)
                        _index = temp_IndexVal--;
                }
                else
                {
                    _index = -1;
                }
            }
        }

        // Add a movie to current position in database
        public void Add(Movie m)
        {
            db.Add(m);
        }

        // Return current movie or null if database empty
        public Movie Get()
        {
            var currentMovie = new Movie();

            if (db[Index] != null)
            {
                currentMovie = db.ElementAt(Index);
            }
            else
            {
                currentMovie = null;
            }

            return currentMovie;
        }

        // Delete current movie at index if there is a movie and update index
        public void Delete()
        {
            if (db[Index] != null)
            {
                db.RemoveAt(Index);
            }
        }

        // Update the current movie at index if there is a movie and update index
        public void Update(Movie m)
        {

        }

        // Delete all movies from the database and reset index
        public void clear()
        {
            db.Clear();
        }

        // Move index position to first movie (0)
        // return true if index update was possible, false otherwise
        public bool First()
        {
            bool updatePossible = false;

            if (db[Index] != db[0])
            {
                Index = 0;
                updatePossible = true;
            }
            return updatePossible;
        }

        // Move index position to last movie
        // true if index update was possible, false otherwise</returns>
        public bool Last()
        {
            bool updatePossible = false;
            int lastMovie = (db.Count - 1);

            if (db[Index] != db[lastMovie])
            {
                Index = lastMovie;
                updatePossible = true;
            }
            return updatePossible;
        }

        // Move index position to next movie
        // true if index update was possible, false otherwise<
        public bool Next()
        {
            bool movePossible = false;
            int lastMovie = (db.Count - 1);

            if (db[Index] != db[lastMovie])
            {
                Index = -2;
                movePossible = true;
            }
            return movePossible;

        }

        // Move index position to previous movie
        // true if index update was possible, false otherwise
        public bool Prev()
        {
            bool movePossible = false;

            if (db[Index] != db[0])
            {
                Index = -3;
                movePossible = true;
            }
            return movePossible;

        }
    }

    // Load movies from a json file and set index to first record
    public void Load(string file)
        {

        }

        // Save movies to a Json file
        public void Save(string file)
        {

        }

        // Following methods update the List of movies (db) to the specified order

        // order the database by year of movie
        public void OrderByYear()
        {

        }

        // order the database by title of movie (ascending)
        public void OrderByTitle()
        {

        }

        // order the database by budget of movie (ascending)
        public void OrderByBudget()
        {

        }

    }
}