using System;
using System.Windows.Forms;

namespace WinFormsApp2
{
    public partial class Form1 : Form
    {
        private const int AGE_LIMIT = 20;

        public Form1()
        {
            InitializeComponent();
            ActivityComboBox.SelectedIndex = 0;
        }

        private void ClearFileDataBtn_Click(object sender, EventArgs e)
        {
            HumansListBox.Items.Clear();
        }

        private void ClearReadedTextBtn_Click(object sender, EventArgs e)
        {
            ReadedFileTextBox.Clear();
        }

        private void WriteToFileBtn_Click(object sender, EventArgs e)
        {           
            var saveDialog = new SaveFileDialog()
            {
                RestoreDirectory = true,
                DefaultExt = "txt"
            };

            var res = saveDialog.ShowDialog();

            if (res != DialogResult.OK || string.IsNullOrEmpty(saveDialog.FileName))
                return;

            try
            {
                using (var writer = new StreamWriter(saveDialog.FileName))
                {
                    foreach (Human human in HumansListBox.Items)
                    {
                        string data = string.Join(Human.FIELDS_DELIMITER, human.FullName,
                            human.Birth.ToShortDateString(), human.Activity);

                        writer.WriteLine(data);
                    }
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

        private void GetInfoBtn_Click(object sender, EventArgs e)
        {
            var openDialog = new OpenFileDialog()
            {
                RestoreDirectory = true
            };

            var res = openDialog.ShowDialog();

            if (res != DialogResult.OK || string.IsNullOrEmpty(openDialog.FileName))
                return;

            ReadedFileTextBox.Clear();

            try
            {
                using (var reader = new StreamReader(openDialog.FileName))
                {
                    while (!reader.EndOfStream)
                    {
                        string data = reader.ReadLine();

                        if (string.IsNullOrEmpty(data))
                            continue;

                        Human human = Human.Parse(data);
                        int age = GetAge(human.Birth);

                        if (age < AGE_LIMIT && human.Activity == Activity.Unemployed)
                            ReadedFileTextBox.Text += human + Environment.NewLine;
                    }
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

        private void AddHumanBtn_Click(object sender, EventArgs e)
        {
            string data = string.Join(Human.FIELDS_DELIMITER, FullNameTextBox.Text,
                BirthTextBox.Text, ActivityComboBox.SelectedItem.ToString());

            try
            {
                Human human = Human.Parse(data);
                HumansListBox.Items.Add(human);
            }
            catch
            {
                MessageBox.Show("Incorrect data.");
            }
        }

        private void DeleteHumanBtn_Click(object sender, EventArgs e)
        {
            if (HumansListBox.SelectedIndex != -1)
                HumansListBox.Items.RemoveAt(HumansListBox.SelectedIndex);
        }

        private static int GetAge(DateTime birth)
        {
            var today = DateTime.Today;
            var age = today.Year - birth.Year - 1;

            age += (today.Month > birth.Month || today.Month == birth.Month && today.Day >= birth.Day)
                ? 1
                : 0;

            return age;
        }
    }
}