To Do List

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.Drawing;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using System.Runtime.InteropServices.ComTypes;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Windows.Forms.VisualStyles;

namespace ToDoList
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            NameUpdate();
        }

        string filename = "Untitled";
        string todo_date, todo_task, todo_status;
        string current_date, current_task, current_status;
        string date_filter, todo_filter, filtered_task;

        private void Form1_Load(object sender, EventArgs e)
        {
            this.comboStatus.SelectedIndex = 3; // set default status เป็น Not Start
            this.comboFilter.SelectedIndex = 4; // set default filter เป็น All
        }

        private void btnAdd_Click(object sender, EventArgs e)
        {
            todo_date = dateTimePicker1.Text;
            todo_task = txtTask.Text;
            todo_status = comboStatus.Text;

            if (todo_task == "") // check ถ้าช่อง task ไม่มีข้อความ ให้ขึ้นแจ้งเตือน
            {
                MessageBox.Show("Please enter your task.","To Do List",MessageBoxButtons.OK,MessageBoxIcon.Warning);
            }
            else
            {
                dgTask.Rows.Add(todo_date, todo_task, todo_status);
                FilterTask();
            }
            txtTask.Text = ""; // clear ค่าในช่อง task
        }

        int ComboMatch(string status_text)
        {
            switch (status_text)
            {
                case "Completed": return 0;
                case "In Progress": return 1;
                case "Cancelled": return 2;
                case "Not Start": return 3;
            }
            return 4;
        }

        private void dgTask_CellClick(object sender, DataGridViewCellEventArgs e)
        {
            if (dgTask.CurrentRow != null)
            {
                current_date = dgTask.CurrentRow.Cells["Date"].Value.ToString();
                current_task = dgTask.CurrentRow.Cells["Task"].Value.ToString();
                current_status = dgTask.CurrentRow.Cells["Status"].Value.ToString();

                CultureInfo provider = CultureInfo.InvariantCulture; // set ให้ไม่สนใจ date format ของเครื่อง
                dateTimePicker1.Value = DateTime.ParseExact(current_date, "dd/MM/yyyy", provider);
                txtTask.Text = current_task;
                comboStatus.SelectedIndex = ComboMatch(current_status);
            }
        }

        private void btnEdit_Click(object sender, EventArgs e)
        {
            todo_date = dateTimePicker1.Text;
            todo_task = txtTask.Text;
            todo_status = comboStatus.Text;

            if (dgTask.CurrentRow != null)
            {
                dgTask.CurrentRow.Cells["Date"].Value = todo_date;
                dgTask.CurrentRow.Cells["Task"].Value = todo_task;
                dgTask.CurrentRow.Cells["Status"].Value = todo_status;
            }
            FilterTask();
        }

        private void btnDelete_Click(object sender, EventArgs e)
        {
            if (dgTask.CurrentRow != null)
            {
                dgTask.Rows.RemoveAt(dgTask.CurrentRow.Index);
                FilterTask();
            }
        }

        void FilterTask()
        {
            date_filter = dateTimePicker2.Text;
            todo_filter = comboFilter.Text;
            filtered_task = "";

            foreach (DataGridViewRow row in dgTask.Rows)
            {
                if (todo_filter == "All")
                {
                    if (row.Cells["Date"].Value.ToString() == date_filter)
                    {
                        filtered_task += row.Cells["Date"].Value.ToString() + "   "
                            + row.Cells["Task"].Value.ToString() + "   "
                            + row.Cells["Status"].Value.ToString() + "\n";
                    }
                } else
                {
                    if (row.Cells["Status"].Value.ToString() == todo_filter &&
                        row.Cells["Date"].Value.ToString() == date_filter)
                    {
                        filtered_task += row.Cells["Date"].Value.ToString() + "   "
                            + row.Cells["Task"].Value.ToString() + "   "
                            + row.Cells["Status"].Value.ToString() + "\n";
                    }
                }
            }

            lblTaskFilter.Text = filtered_task;
        }

        private void dateTimePicker2_ValueChanged(object sender, EventArgs e)
        {
            FilterTask();
        }

        private void comboFilter_SelectedIndexChanged(object sender, EventArgs e)
        {
            FilterTask();
        }

        private void btnOpen_Click(object sender, EventArgs e)
        {
            OpenFileDialog openFileDialog1 = new OpenFileDialog();
            openFileDialog1.Filter = "Text Files|*.txt";
            openFileDialog1.Title = "Open Text File";
            openFileDialog1.ShowDialog();

            if (openFileDialog1.FileName != "")
            {
                filename = Path.GetFileName(openFileDialog1.FileName);
                dgTask.Rows.Clear();

                string[] lines = File.ReadAllLines(openFileDialog1.FileName);
                foreach (string line in lines)
                {
                    string[] cols = line.Split('\t');
                    dgTask.Rows.Add(cols[0], cols[1], cols[2]);
                }
            }

            NameUpdate();
            FilterTask();
        }

        private void btnSave_Click(object sender, EventArgs e)
        {
            SaveFileDialog saveFileDialog1 = new SaveFileDialog();
            saveFileDialog1.Filter = "Text Files|*.txt";
            saveFileDialog1.Title = "Save as Text File";
            saveFileDialog1.ShowDialog();

            if (saveFileDialog1.FileName != "")
            {
                using (StreamWriter writer = new StreamWriter(saveFileDialog1.FileName, false, Encoding.UTF8))
                {
                    foreach (DataGridViewRow row in dgTask.Rows)
                    {
                        string line = row.Cells["Date"].Value + "\t" + row.Cells["Task"].Value + "\t" + row.Cells["Status"].Value;
                        writer.WriteLine(line);
                    }
                }

                filename = Path.GetFileName(saveFileDialog1.FileName);
            }

            NameUpdate();
        }

        void NameUpdate()
        {
            this.Text = "To Do List - " + filename;
        }
    }
}