using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using System.Windows.Forms;
using Newtonsoft.Json;

namespace UseCases
{
    public partial class FrmMain : Form
    {
        [DllImport("kernel32")]
        static extern bool AllocConsole();

        enum AddAction
        {
            Nothing,
            Actor,
            UseCase
        }

        public FrmMain()
        {
            //get the command line arguments
            var args = Environment.GetCommandLineArgs();

            InitializeComponent();

            //check if there are multiple arguments
            if (args.Count() > 1)
            {
                //check if first arguments is a file
                if (File.Exists(args[1]))
                {
                    //try to open the file
                    OpenFile(args[1]);
                }
                else
                {
                    Diagram = new Diagram();
                    //initialise default values
                }
            }
            else
            {
                //initialise default values
                Diagram = new Diagram();
            }
        }

        #region variables

        //actors and usecases
        public Diagram Diagram { get; private set; }

        //drawing variables
        private readonly Font _myFont = new Font("Sans Sherif", 20f, FontStyle.Regular);
        private readonly Pen _drawingPen = new Pen(Color.Black, 3f);

        //adding elements
        private AddAction _toAdd = AddAction.Nothing;

        private IDrawable _dragged = null;

        //edit tracker
        private bool _hasEdited = false;

        #endregion

        #region menustrip

        private void exitToolStripMenuItem_Click(object sender, EventArgs e)
        {
            Close();
        }

        private void btAddActor_Click(object sender, EventArgs e)
        {
            _toAdd = AddAction.Actor;
        }

        private void btAddUseCase_Click(object sender, EventArgs e)
        {
            _toAdd = AddAction.UseCase;
        }

        //save in json format
        private void btSave_Click(object sender, EventArgs e)
        {
            //show save file dialog and quit if canceled
            var saveDiag = new SaveFileDialog {Filter = @"*.ucd|*.ucd"};
            if (saveDiag.ShowDialog() != DialogResult.OK) return;
            _hasEdited = false;
            
            Diagram.Size = Size;
            Diagram.Maximized = WindowState == FormWindowState.Maximized;
            //save to file
            var serialized = JsonConvert.SerializeObject(Diagram, Utils.SerializerSettings);
            File.WriteAllText(saveDiag.FileName, serialized);
        }

        //save png format
        private void btSaveImage_Click(object sender, EventArgs e)
        {
            //show save file dialog and quit if canceled
            var saveDiag = new SaveFileDialog {Filter = @"*.png|*.png"};
            if (saveDiag.ShowDialog() != DialogResult.OK) return;
            //create bitmap and draw usecases and actors to it
            var bmp = new Bitmap(Size.Width, Size.Height);
            var g = Graphics.FromImage(bmp);
            DrawElements(g);
            //save image to file
            bmp.Save(saveDiag.FileName);
        }

        //open json format
        private void btOpen_Click(object sender, EventArgs e)
        {
            //check if anything has been edited
            if (_hasEdited)
            {
                if (
                    MessageBox.Show(@"Are you sure you want to load a new file?", @"Load new file",
                        MessageBoxButtons.YesNo) == DialogResult.No)
                    return;
            }

            //show open file dialog and quit if canceled
            var openDiag = new OpenFileDialog {Filter = @"*.ucd|*ucd"};
            if (openDiag.ShowDialog() != DialogResult.OK) return;
            //open the file
            OpenFile(openDiag.FileName);

            Refresh();
        }

        private void clearToolStripMenuItem_Click(object sender, EventArgs e)
        {
            //check if user realy wants to clear the diagram else return
            if (MessageBox.Show(@"Are you sure you want to clear the diagram?", @"Clear", MessageBoxButtons.YesNo) !=
                DialogResult.Yes) return;
            //clear lists and refresh screen
            Diagram = new Diagram(new Size(430, 372));
//            _actors.Clear();
//            _useCases.Clear();
            WindowState = FormWindowState.Normal;
            Size = Diagram.Size;
            Refresh();
        }

        private void controlsToolStripMenuItem_Click(object sender, EventArgs e)
        {
            MessageBox.Show(@"Pres Ctrl+A or click Add>Actor to add an Actor
Press Ctrl+U or click File>Use Case to add a Use Case
Click somwhere on screen to add Use Case or Actor at that position
Leave name empty to remove
Click and drag to move usecase or actor
Press Ctrl+S or click File>Save to save the diagram
Press Ctrl+Shift+S or click File>Save as image to save diagram as image
Click File>Clear to clear the diagram
Press Alt+F4 or click the cross or click File>Exit to close the form
Click Help>Controls to view this message
Click Help>About to view information about the application", @"Controls");
        }

        private void aboutToolStripMenuItem_Click(object sender, EventArgs e)
        {
            MessageBox.Show(@"Use Case Designer by Rick Rongen
Version 1.0

Developed by order of Fontys Hogerescholen ICT Eindhoven", @"About");
        }

        #endregion

        #region functions
        /// <summary>
        /// Opens an file into form and shows error if it could not be loaded
        /// </summary>
        /// <param name="filename">full path of ile to load</param>
        private void OpenFile(string filename)
        {
            //try to open file
            try
            {
                Diagram = JsonConvert.DeserializeObject<Diagram>(File.ReadAllText(filename), Utils.SerializerSettings);
                WindowState = Diagram.Maximized ? FormWindowState.Maximized : FormWindowState.Normal;
                Size = Diagram.Size;
                Refresh();
            }
            catch (JsonException jex)
            {
                //show the console with the error if the user wan't to see it
                if (
                    MessageBox.Show(
                        $@"Error while loading {filename}\n
Invallid format or broken data\nGeeks may check console for the exception, pres yes to show console",
                        @"Error occured, show console?", MessageBoxButtons.YesNo) == DialogResult.Yes) AllocConsole();
                Console.WriteLine(jex.ToString());
            }
            catch (IOException ioex)
            {
                //show the console with the error if the user wan't to see it
                if (
                    MessageBox.Show(
                        $@"Error while loading {filename}\nCouldn't open the file or there was an encoding issue.",
                        @"Error occured, show console?", MessageBoxButtons.YesNo) == DialogResult.Yes) AllocConsole();
                Console.WriteLine(ioex.ToString());
            }
            finally
            {
                _hasEdited = false;
            }
        }

        /// <summary>
        /// Draws all ellements in actors and useCases to the graphics object
        /// </summary>
        /// <param name="g">graphics object</param>
        private void DrawElements(Graphics g)
        {
            g.SmoothingMode = SmoothingMode.AntiAlias;
            foreach (var drawable in Diagram.Drawable)
            {
                drawable.Draw(g, _myFont, _drawingPen);
            }
        }

        #endregion

        #region mouse

        //handle creation of components
        private void frmMain_Click(object sender, EventArgs e)
        {
            var pos = PointToClient(MousePosition);
            switch (_toAdd)
            {
                case AddAction.Actor:
                    //create new actor
                    var adiag = new EditActor();
                    if (adiag.ShowDialog() == DialogResult.OK && adiag.ActorName != "")
                    {
                        Diagram.Actors.Add(new Actor(adiag.ActorName, pos));
                    }

                    Refresh();
                    break;
                case AddAction.UseCase:
                    //create new useCase
                    var udiag = new editUseCase(Diagram.Actors) {UseCase = new UseCase(), CasePos = pos};
                    if (udiag.ShowDialog() == DialogResult.OK && udiag.UseCase.Name != "")
                    {
                        Diagram.UseCases.Add(udiag.UseCase);
                        udiag.UseCase.Actors.ForEach(Console.WriteLine);
                    }

                    Refresh();
                    break;
                default:
                case AddAction.Nothing:
                    break;
            }

            _toAdd = AddAction.Nothing;
            if (Diagram.UseCases.Any() || Diagram.Actors.Any()) _hasEdited = true;
        }

        //handle editing of components
        private void frmMain_DoubleClick(object sender, EventArgs e)
        {
            var mousepos = PointToClient(MousePosition);
            var closest = GetClosestDrawable(mousepos);

            switch (closest)
            {
                case null:
                    return;
                case Actor actor:
                    var edAcDiag = new EditActor(actor.Name);
                    if (edAcDiag.ShowDialog() == DialogResult.OK)
                    {
                        if (edAcDiag.ActorName == "")
                        {
                            //remove actor if name is equal to ""
                            Diagram.Actors.Remove(actor);
                            foreach (var usecase in Diagram.UseCases)
                            {
                                //remove this actor from all refering usecases
                                usecase.Actors.Remove(actor);
                            }
                        }
                        else
                        {
                            //update name
                            actor.Name = edAcDiag.ActorName;
                        }
                    }
                    break;
                case UseCase useCase:
                    var edUcDiag = new editUseCase(Diagram.Actors)
                    {
                        UseCase = useCase,
                        CasePos = useCase.Position
                    };
                    if (edUcDiag.ShowDialog() == DialogResult.OK)
                    {
                        if (edUcDiag.UseCase.Name == "")
                        {
                            //remove usecase if name is equal to ""
                            Diagram.UseCases.Remove(useCase);
                        }
                    }
                    break;
            }
            Refresh();
        }

        //move usecase or actor
        private void frmMain_MouseUp(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left && _toAdd == AddAction.Nothing)
            {
                _dragged = null;
            }
        }

        private void frmMain_MouseDown(object sender, MouseEventArgs e)
        {
            //quit if not left mousebutton or adding item
            if (e.Button != MouseButtons.Left || _toAdd != AddAction.Nothing) return;

            //get mouse position in client
            var mousepos = PointToClient(MousePosition);

            var closest = GetClosestDrawable(mousepos);
            if (closest == null)
                return;
            _dragged = closest;
        }

        private void frmMain_MouseMove(object sender, MouseEventArgs e)
        {
            if (_dragged == null) return;
            _dragged.Position = PointToClient(MousePosition);
            Refresh();
        }

        private IDrawable GetClosestDrawable(Point position, double maxDistance = 30d)
        {
            if (!Diagram.UseCases.Any() && !Diagram.Actors.Any())
                return null; // No items to check
            var comm = Diagram.Drawable.Select(org => new
                {
                    original = org,
                    distance = Math.Sqrt(Math.Pow(org.Position.X - position.X, 2) +
                                         Math.Pow(org.Position.Y - position.Y, 2))
                }).Aggregate((a1, a2) => a1.distance < a2.distance ? a1 : a2);
            return comm.distance > maxDistance ? null : comm.original;
        }

        #endregion

        private void frmMain_Paint(object sender, PaintEventArgs e)
        {
            //draw actors, use cases and lines
            DrawElements(e.Graphics);
        }

        private void FrmMain_FormClosing(object sender, FormClosingEventArgs e)
        {
            if (!_hasEdited) return;
            if (MessageBox.Show(@"Are you sure you want to exit?", @"exit", MessageBoxButtons.YesNo) !=
                DialogResult.Yes)
                e.Cancel = true;
        }
    }
}