ilyalehchylin/educats-xamarin

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using EduCATS.Data;
using EduCATS.Data.Models;
using EduCATS.Helpers.Forms;
using EduCATS.Helpers.Logs;
using Nyxbull.Plugins.CrossLocalization;
using Xamarin.Forms;

namespace EduCATS.Pages.Pickers
{
    /// <summary>
    /// Subjects view model.
    /// </summary>
    /// <remarks>Used for Subjects picker.</remarks>
    public class SubjectsViewModel : ViewModel
    {
        /// <summary>
        /// Platform services.
        /// </summary>
        public readonly IPlatformServices PlatformServices;

        public List<SubjectModel> CurrentSubjects { get; set; }
        public SubjectModel CurrentSubject { get; set; }

        public delegate void SubjectEventHandler(int id, string name);
        public event SubjectEventHandler SubjectChanged;

        public SubjectsViewModel(IPlatformServices platformServices)
        {
            PlatformServices = platformServices;
        }

        string _chosenSubject;
        public string ChosenSubject {
            get { return _chosenSubject; }
            set { SetProperty(ref _chosenSubject, value); }
        }

        string _chosenSubjectColor;
        public string ChosenSubjectColor {
            get { return _chosenSubjectColor; }
            set { SetProperty(ref _chosenSubjectColor, value); }
        }

        Command _chooseSubjectCommand;
        public Command ChooseSubjectCommand {
            get {
                return _chooseSubjectCommand ?? (
                    _chooseSubjectCommand = new Command(chooseSubject));
            }
        }

        Command _subjectSelectedCommand;
        public Command SubjectSelectedCommand {
            get {
                return _subjectSelectedCommand ?? (_subjectSelectedCommand = new Command(subjectChosen));
            }
        }

        protected void chooseSubject()
        {
            try {
                if (CurrentSubjects == null) {
                    return;
                }

                var buttons = new Dictionary<int, string>();
                foreach (var subject in CurrentSubjects) {
                    buttons.Add(subject.Id, subject.Name);
                }

                PlatformServices.Dialogs.ShowSheet(
                    CrossLocalization.Translate("subjects_choose"), buttons, SubjectSelectedCommand);
            } catch (Exception ex) {
                AppLogs.Log(ex);
            }
        }

        protected void subjectChosen(object chosenObject)
        {
            try {
                var id = Convert.ToInt32(chosenObject);

                if (id == -1) {
                    return;
                }

                var subject = CurrentSubjects.SingleOrDefault(s => s.Id == id);
                var isChosen = setChosenSubject(subject);

                if (isChosen) {
                    SubjectChanged?.Invoke(PlatformServices.Preferences.ChosenSubjectId, subject.Name);
                }
            } catch (Exception ex) {
                AppLogs.Log(ex);
            }
        }

        /// <summary>
        /// Setup subjects.
        /// </summary>
        /// <returns>Task.</returns>
        public async Task SetupSubjects()
        {
            try {
                var subjects = await getSubjects();

                if (subjects == null) {
                    return;
                }

                SetCurrentSubjectsList(subjects.Distinct().ToList());
                SetupSubject();
            } catch (Exception ex) {
                AppLogs.Log(ex);
            }
        }

        /// <summary>
        /// Fetch subjects.
        /// </summary>
        /// <returns>List of subjects.</returns>
        async Task<IList<SubjectModel>> getSubjects()
        {
            var subjects = await DataAccess.GetProfileInfoSubjects(PlatformServices.Preferences.UserLogin);

            if (DataAccess.IsError) {
                PlatformServices.Device.MainThread(
                    () => PlatformServices.Dialogs.ShowError(DataAccess.ErrorMessage));
            }

            return subjects;
        }

        /// <summary>
        /// Setup subject by subject name.
        /// </summary>
        public void SetupSubject()
        {
            if (!checkSubjectsList()) {
                return;
            }

            var savedSubjectId = PlatformServices.Preferences.ChosenSubjectId;
            var success = setChosenSubject(savedSubjectId);

            if (!success) {
                setChosenSubject(CurrentSubjects[0]);
            }
        }

        bool setChosenSubject(int subjectId)
        {
            var subject = CurrentSubjects.SingleOrDefault(
                        s => s.Id == subjectId);

            return setChosenSubject(subject);
        }

        bool setChosenSubject(SubjectModel subject)
        {
            if (subject != null) {
                CurrentSubject = subject;
                ChosenSubject = subject.Name;
                ChosenSubjectColor = subject.Color;
                PlatformServices.Preferences.ChosenSubjectId = subject.Id;
                return true;
            }

            return false;
        }

        public void SetCurrentSubjectsList(List<SubjectModel> subjects)
        {
            CurrentSubjects = subjects.OrderBy(x => x.Name).ToList();
        }

        bool checkSubjectsList()
        {
            if (CurrentSubjects != null && CurrentSubjects.Count > 0) {
                return true;
            }

            return false;
        }
    }
}