/*
 * SpacePirate.cs
 * Authors:     August Zinsser
 * 
 * Copyright Matthew Belmonte 2007
 */


using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using Pina3D.Particles;
using tAC_Engine;


namespace Astropolis
{
    /// <summary>
    /// The enemy ships that spawn from wormholes in meteor madness
    /// Space Pirates can shoot at the player
    /// They also explode when the player shoots them enough times or they hit enough meteors
    /// Upon explosion, they drop coins that can be collected by the player
    /// </summary>
    class SpacePirate : UFO
    {
        private double mArcPosition;     // Degrees of a circle corresponding to the player's ship's position
        private double mArcVelocity;     // Speed at which the ship can change its arcposition
        private float mCooldownTime;     // The minimum base time between shots
        private float mCooldownTimer;    // Counts down until the next shot


        public double ArcPosition { set { mArcPosition = value; UpdatePosition(); } get { return mArcPosition; } }
        public double ArcVelocity { set { mArcVelocity = value; } get { return mArcVelocity; } }


        /// <summary>
        /// Constructor
        /// </summary>
        /// <param name="texture">Image to use</param>
        /// <param name="width">In Space3D units</param>
        /// <param name="height">In Space3D units</param>
        /// <param name="depth">In Space3D units</param>
        /// <param name="hitPoints">Damage this ship can take before dying</param>
        /// <param name="shotCooldown">Base time between shots, although this time is reduced at later levels</param>
        public SpacePirate(Texture2D texture, float width, float height, float depth, int hitPoints, float shotCooldown)
            : base(texture, width, height, depth, hitPoints)
        {
            mArcVelocity = Math.PI / 1920;
            mCooldownTimer = (3 + (shotCooldown * 2)) * GenericBaseApplication.GameManager.RandomNumber(.90f, 1.10f);   // Wait for the player to react before opening fire
            mCooldownTime = shotCooldown;

        }


        /// <summary>
        /// Deals the specified amount of damage to the space priate, potentially killing it
        /// </summary>
        /// <param name="damage"></param>
        public override void GetHit(int damage)
        {
            mHitPoints -= damage;
            if (mHitPoints <= 0)
                Destroy();
            else
            {
                if (mPos.Z > -1)
                {
                    // Shield particle effect
                    mShieldEmitter.RegularEmissionType.LifeExpectancy = .1f;
                    mShieldEmitter = Sparx.LoadParticleEffect(@"Content\Particle Effects\Shield.spx");

                    // Redden the shields to indicate that they are low
                    float percentLeft = (float)(mHitPoints / 100f);
                    Color newColor = new Color((byte)((255 * (1 - percentLeft))),
                                               (byte)((150 * (percentLeft))),
                                               (byte)((255 * (percentLeft))));
                    mShieldEmitter.RegularEmissionType.Modifiers[0].InitialTint = newColor;
                    mShieldEmitter.RegularEmissionType.Modifiers[0].InitialOpacity = percentLeft;
                    Sparx.AddEmitter(mShieldEmitter);
                }
            }
        }


        /// <summary>
        /// Spawns the appropriate particle effects and/or entities
        /// </summary>
        public override void Destroy()
        {
            mAlive = false;
            Emitter splosion = Sparx.LoadParticleEffect(@"Content\Particle Effects\MediumExplosion.spx");
            Rectangle proj = Space3D.Project(this.X, this.Y, this.Z, this.Width, this.Height, -1f);
            float scaling = proj.Width * .01f;
            splosion.RenderScale = scaling;
            splosion.Transform = Matrix.CreateScale(scaling) * Matrix.CreateTranslation(proj.X, proj.Y, MathHelper.Clamp(this.Z / 5f, 0f, 1f)); 
            Sparx.AddEmitter(splosion);
            splosion = Sparx.LoadParticleEffect(@"Content\Particle Effects\MediumExplosion.spx");
            scaling *= .5f;
            splosion.RenderScale = scaling;
            splosion.Transform = Matrix.CreateScale(scaling) * Matrix.CreateTranslation(proj.X, proj.Y, MathHelper.Clamp(this.Z / 5f, 0f, 1f));
            Sparx.AddEmitter(splosion);
        }


        /// <summary>
        /// Damages player
        /// </summary>
        public override void CollideWithPlayer(Entity player)
        {
            ((MeteorMadness)AstroBaseApplication.MiniGame).ShooterShieldHit(50);
            Destroy();
        }


        /// <summary>
        /// Implements basic AI
        /// </summary>
        /// <returns>True if the AI should fire, false if it should not</returns>
        public override bool React(CheetahFighter playerShip)
        {
            float dt = AstroBaseApplication.GameManager.ElapsedMilliseconds;
            mCooldownTimer -= dt / 1000;

            if (playerShip == null)
                return false;

            if (Math.Abs(mArcPosition - playerShip.ArcPosition) > .01)
            {
                if (mArcPosition < playerShip.ArcPosition)
                    MoveLeft(dt);
                else
                    MoveRight(dt);
            }

            // Fire if the space pirate is lined up with the player
            if (Collides2D(this, playerShip) && mCooldownTimer < 0)
            {
                Fire();
                return true;
            }

            return false;
        }


        /// <summary>
        /// Moves the space pirate clockwise along the circumference of the Space3D cylinder
        /// </summary>
        /// <param name="dt">Seconds since last update</param>
        private void MoveLeft(float dt)
        {
            mArcPosition += mArcVelocity * dt;
            UpdatePosition();
        }


        /// <summary>
        /// Moves the space pirate counterclockwise along the circumference of the Space3D cylinder
        /// </summary>
        /// <param name="dt">Seconds since last update</param>
        private void MoveRight(float dt)
        {
            mArcPosition -= mArcVelocity * dt;
            UpdatePosition();
        }


        /// <summary>
        /// Reset the firing cooldown
        /// </summary>
        private void Fire()
        {
            mCooldownTimer = mCooldownTime;
        }


        /// <summary>
        /// Updates the inherited Position properties based on the arcposition
        /// </summary>
        private void UpdatePosition()
        {
            Vector2 PositionFromOrigin = new Vector2((float)Math.Cos(mArcPosition), (float)Math.Sin(mArcPosition));
            mArcPosition %= Math.PI * 2;
            mPos.X = .8F * PositionFromOrigin.X;
            mPos.Y = .8F * PositionFromOrigin.Y;
            mRot = mArcPosition - Math.PI / 2;
        }


        public override void Update()
        {
            base.Update();

            Rectangle proj = Space3D.Project(this.X, this.Y, this.Z, this.Width, this.Height, -1f);
            float scaling = proj.Width * .015f;
            mShieldEmitter.RenderScale = scaling;
            mShieldEmitter.Transform = Matrix.CreateScale(scaling) * Matrix.CreateTranslation(proj.X, proj.Y, MathHelper.Clamp(this.Z / 5f, 0f, 1f));
        }
    }
}