using System;
using System.IO;
using System.Drawing;
using System.Threading;
using System.Collections;
using System.Windows.Forms;
using System.Reflection;

namespace Pocket1945
{
	/// <summary>
	/// This is the actuall gameform used to display the game to the user. 
	/// The class inherits the System.Windows.Forms.Form class.	
	/// </summary>
	public class GameForm : Form
	{		
		//Private game variables.
		private bool playing;		
		private Bitmap offScreenBitmap;
		private Graphics offScreenGraphics;
		private Graphics onScreenGraphics;		
		private LevelGui levelGui;
		private Input input;		
		private string[] levelFiles;
		private int menuTick;
		private int titleTick;
		private GameFont levelFont;
		private GameFont exitFont;

		/// <summary>
		/// Which level the player is on.
		/// </summary>
		public static int LevelCount;
		
		/// <summary>
		/// A public static instance of the player.
		/// </summary>
		public static Player Player;		

		/// <summary>
		/// A public static int counting the number of ticks used
		/// in the game.
		/// </summary>
		public static int TickCount;

		/// <summary>
		/// A public static rectangle determing the size of the 
		/// game area.
		/// </summary>
		public static Rectangle GameArea;

		/// <summary>
		/// A public static randomizer used by all game objects to
		/// generate random numbers.
		/// </summary>
		public static Random Randomizer;

		/// <summary>
		/// Field holding a public static reference to the current level. 
		/// Trough this field other game objects like bullets, players and enemies 
		/// gain access to the level properties.
		/// </summary>
		public static Level CurrentLevel;

		/// <summary>
		/// The framerate of the game. This const is used to determine speed
		/// for all game object. The speed of the game is mesured in pixel pr. second.
		/// So, if a enemy moves 30 pixel pr second the speed variable is PixelPerSecond / FramesPerSecond.
		/// 
		/// Variables like ReloadTime is messured in seconds, so the tick variable is Seconds * FramesPerSecond.
		/// </summary>
		internal const float FramesPerSecond = 30F;

		/// <summary>
		/// The lenght of one frame (1 second / FramesPerSecond).
		/// </summary>
		internal const float SecondsPerFrame = 1.0F / FramesPerSecond;
		
		/// <summary>
		/// Instanciates the main game form.
		/// </summary>
		public GameForm()
		{			
			TickCount = 0;			
			this.Visible = true;			
			this.WindowState = FormWindowState.Maximized;									
			offScreenBitmap = new Bitmap(this.ClientRectangle.Width, this.ClientRectangle.Height);			
			offScreenGraphics = Graphics.FromImage(offScreenBitmap);
			offScreenGraphics.Clear(Color.Black);
			GameArea = this.ClientRectangle;			

			SpriteList.Instance.LoadSprites();
		
			Randomizer = new Random(DateTime.Now.Millisecond);						
			Player = new Player();
			input = new Input();			
			levelGui = new LevelGui();
			levelFiles = GetLevels();
			levelFont = new GameFont(Color.Yellow, string.Empty, new Font(FontFamily.GenericSansSerif, 24, FontStyle.Bold), 60, 130);			
			exitFont = new GameFont(Color.Red, string.Empty, new Font(FontFamily.GenericSansSerif, 10, FontStyle.Bold), 70, 160);
			
			titleTick = 120;
			DoGameLoop();
		}

		/// <summary>
		/// The game loop.
		/// </summary>
		private void DoGameLoop()
		{
			playing = true;
			onScreenGraphics = this.CreateGraphics();			
			input.RegisterAllHardwareKeys();
			
			while(playing)
			{
				DoLevel(levelFiles[LevelCount]);
			}
			
			input.UnregisterAllHardwareKeys();
			onScreenGraphics.Dispose();
			Application.DoEvents();
			Application.Exit();
		}

		/// <summary>
		/// The level loop.
		/// </summary>
		private void DoLevel(string filename)
		{	
			CurrentLevel = new Level(GetFullPath(filename));
			StopWatch sw = new StopWatch();
			bool levelCompleted = false;
			bool displayMenu = false;

			while((playing) && (!levelCompleted))
			{
				// Store the tick at which this frame started
				Int64 startTick = sw.CurrentTick();				
				input.Update();		
	
				//Update the rownumber.
				TickCount++;				
							
				//Draw the background map.					
				CurrentLevel.BackgroundMap.Draw(offScreenGraphics);				

				//Update bullets, enemies and bonuses.
				HandleBonuses();
				HandleBullets();				
				HandleEnemies();				

				//Update and draw the player.
				Player.Update(input);	
				Player.Draw(offScreenGraphics);
				playing = (Player.Status != PlayerStatus.Dead);

				//Draw in-game user interface
				levelGui.Draw(offScreenGraphics);

				//Draw level title.
				if(titleTick > 0)
				{
					titleTick--;
					levelFont.Text = CurrentLevel.Name;
					levelFont.Draw(offScreenGraphics);
				}

				//Display a simple menu.
				if (displayMenu)
				{
					menuTick--;
					if(menuTick == 0)
						displayMenu = false;

					if (input.KeyJustPressed(193))					
						playing = false;
					exitFont.Text = "Click again to Exit";
					exitFont.Draw(offScreenGraphics);
				}

				if (input.KeyJustPressed(193))
				{
					menuTick = 120;
					displayMenu = true;
				}

				//Check if the level is compleated.
				if(CurrentLevel.BackgroundMap.Y == 0)
				{
					LevelCount++;
					titleTick = 120;
					if(LevelCount == levelFiles.Length)
						LevelCount = 0;
					Player.Power = Player.ShieldThickness;
					Player.UpdateHealth();
					levelCompleted = true;
				}
							
				//Move the offScreenBitmap buffer to the screen.
				onScreenGraphics.DrawImage(offScreenBitmap, 0, 0, this.ClientRectangle, GraphicsUnit.Pixel);				
				
				//Process all events in the event que.
				Application.DoEvents();				
				
				// Lock the framerate...
				Int64 deltaMs = sw.DeltaTime_ms(sw.CurrentTick(), startTick);
				Int64 targetMs = (Int64)(1000.0F * SecondsPerFrame);

				// Check if the frame time was fast enough
				if (deltaMs <= targetMs)
				{
					// Loop until the frame time is met
					while (sw.DeltaTime_ms(sw.CurrentTick(), startTick) < targetMs)
					{
						Thread.Sleep(0);
						Application.DoEvents();
					}
				}
			}			
		}

		#region Method handeling bonus elements.
		/// <summary>
		/// Method handeling all the bonus elements in the game.
		/// </summary>
		private void HandleBonuses()
		{
			for(int i = 0; i < CurrentLevel.Bonuses.Length; ++i)
			{
				Bonus b = (Bonus)CurrentLevel.Bonuses[i];
				if(b.HasFocus())
				{
					b.Move();
					b.Draw(offScreenGraphics);

					//Check if the player have collected the bonus.
					if(b.GetCollitionRectangle().IntersectsWith(Player.GetCollitionRectangle()))
					{						
						Player.GetBonus(b);
						b.Collected = true;
					}
				}
			}
		}
		#endregion

		#region Method handeling bullets.
		/// <summary>
		/// Method handeling all the bullets in the game.
		/// </summary>
		private void HandleBullets()
		{
			//Loop trough all bullets in the game.
			for(int i = 0; i < CurrentLevel.Bullets.Count; ++i)
			{
				Bullet b = (Bullet)CurrentLevel.Bullets[i];

				//Check if the bullet has focus.
				if(b.HasFoucs())
				{
					b.Move();
					b.Draw(offScreenGraphics);

					//If the bullet is mowing upwards it's aimed at enemies.
					if(b.Direction == MoveDirection.Up)
					{
						//Loop trough the enemies and check for a hit.
						for(int j = 0; j < CurrentLevel.Enemies.Length; ++j)
						{
							Enemy e = (Enemy)CurrentLevel.Enemies[j];																
							//Check if we got a hit.
							if(e.HasFocus() && e.Status != EnemyStatus.Dying && b.GetCollitionRectangle().IntersectsWith(e.GetCollitionRectangle())) 
							{						
								//The bullet hit a enemey.
								e.Hit(b);

								//Remove the bullet from the game.
								CurrentLevel.Bullets.RemoveAt(i);

								//Collect score.
								if(e.Status == EnemyStatus.Dying)
									Player.Score += e.GiveScore();
								break;
							}
						}
					}
					//If the bullet is moving downwards it's aimed at the player.
					else
					{
						//Check if the enemey hits the player.
						if(b.GetCollitionRectangle().IntersectsWith(Player.GetCollitionRectangle()))
						{
							//Hit the player and remove the bullet.
							Player.Hit(b);
							CurrentLevel.Bullets.RemoveAt(i);								
						}
					}						
				}
				//The bullet is out of scope remove the bullet to free memory.
				else
					CurrentLevel.Bullets.RemoveAt(i);
			}
		}
		#endregion

		#region Method handeling enemies.
		/// <summary>
		/// Method handeling all the enemies of the game.
		/// </summary>
		public void HandleEnemies()
		{
			//Loop trough all enemies and move, draw and fire.
			for(int i = 0; i < CurrentLevel.Enemies.Length; ++i)
			{
				Enemy e = (Enemy)CurrentLevel.Enemies[i];					
				if(e.HasFocus())
				{		
					//Move the enemey.
					e.Move();

					//If the enemy can fire, add a new bullet to the game.
					if(e.CanFire())
						CurrentLevel.Bullets.Add(e.Fire());

					//Draw the enemey.
					e.Draw(offScreenGraphics);

					//Check if the player collides with a enemy plane.
					if(e.Status != EnemyStatus.Dying && e.GetCollitionRectangle().IntersectsWith(Player.GetCollitionRectangle()))
					{
						//The effect of a collition is the same as if they where hit by a bullet.
						Player.Hit(e.Fire());						
						e.Hit(Player.Fire());

						//Give score if the enemy is dying.
						if(e.Status == EnemyStatus.Dying)
							Player.Score += e.GiveScore();
					}
				}
			}
		}
		#endregion

		/// <summary>
		/// Method returning a string array with all level files in the game folder.
		/// </summary>
		/// <returns>All level files.</returns>
		public string[] GetLevels()
		{
			Assembly asm = Assembly.GetExecutingAssembly();
			DirectoryInfo dir = new DirectoryInfo(Path.GetDirectoryName(asm.GetName().CodeBase));
			FileInfo[] files = dir.GetFiles("*.xml");
			string[] fileNames = new string[files.Length];			
			for(int i = files.Length; i > 0; --i)						
				fileNames[i - 1] = files[files.Length - i].Name;
			return fileNames;
		}

		/// <summary>
		/// Method used to determine the full path of a file.
		/// </summary>
		/// <param name="fileName">The filename you want the full path for.</param>
		/// <returns>The full paht of the file.</returns>
		private string GetFullPath(string fileName)
		{
			Assembly asm = Assembly.GetExecutingAssembly();
			string fullName = Path.GetDirectoryName(asm.GetName().CodeBase);
			return Path.Combine(fullName, fileName);
		}
		
		/// <summary>
		/// Left empty, all drawing is done in the game loop.
		/// </summary>
		/// <param name="e">Event arguments.</param>
		protected override void OnPaint(PaintEventArgs e) {}

		/// <summary>
		/// Since all drawing is done in the gameloop the Form does not need 
		/// to draw a background for us. By leaving this method empty we 
		/// avoids undesirable flickering.
		/// </summary>
		/// <param name="e">Event arguments.</param>
		protected override void OnPaintBackground(PaintEventArgs e) {}
		
		/// <summary>
		/// Entrypoint of the application starting the game.
		/// </summary>
		public static void Main() 
		{
			Application.Run(new GameForm());
		}
	}
}