using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Azimuth;
using Annulus;
using Slipstream.StokesFlow;

namespace Slipstream.Testbed.Demos
{
    class UniformFlowStokesPanelSidways : Demo
    {
        StokesPanelGroup _panelGroup;
        Scalar panelLength = 10;
        public override void Start(FluidWorld world)
        {
            _panelGroup = new StokesPanelGroup(
                new[] { Vector.Zero },
                new[] { Vector.UnitY },
                panelLength);
            Random rand = new Random(1);
            for (int i = 0; i < 1000; ++i)
            {
                world.AddTracerParticle(new Vector(2 * rand.NextDouble() - 1, 2 * rand.NextDouble() - 1) * 100);
            }
        }

        Scalar cycleCount = 0;
        public override void Update(FluidWorld world)
        {
            cycleCount += 1.0 / 60.0;

            Scalar period = 10;
            Scalar angularVelocity = (1.0 / period) * (2 * Math.PI);

            var velocity = new Vector(0, 25 * angularVelocity * Math.Cos(angularVelocity * cycleCount));
            world.FluidBaseVelocity = velocity;

            Scalar totalEnergyCount;
            _panelGroup.EnforceBoundaryConditions(world.FluidBaseVelocity);
            Action<DenseVector, DenseVector, DenseVector, DenseVector> particles = (x, y, velx, vely) =>
            {
                for (int i = 0; i < x.Count; ++i)
                {
                    var velocityPanel = _panelGroup.VelocityAtPoint(new Vector(x[i], y[i]));
                    velx[i] = velocityPanel.X;
                    vely[i] = velocityPanel.Y;

                }
            };
            world.IntegrateTracerParticles(particles, 1.0/60.0, out totalEnergyCount);
        }

        public override void Reset(FluidWorld world)
        {
            cycleCount = 0;
        }

        public override Blacklight.Core.Cel Draw(FluidWorld world)
        {
            var cel = new Blacklight.Core.Cel();
            var collage = new Blacklight.Core.Drawables.Collage();

            var panelCollage = new Blacklight.Core.Drawables.Collage();
            var panel = new Blacklight.Core.Drawables.Rectangle
            {
                InsideColor = new Blacklight.Core.Color(0.84, 0.84, 0),
                ShellColor = new Blacklight.Core.Color(0.84, 0.25, 0),
                ShellPixelThickness = 0,
                ShellModelSpaceThickness = 0,
                SmoothBorder = false,
            };
            panelCollage.AddDrawable(panel, new AffineMatrix(
                new Vector(panelLength * 0.5 * 0.66, 0), new Vector(0, 0.5), new Vector(0, 0)));

            foreach (var panelTransform in _panelGroup.PanelsModelToWorld)
            {
                collage.AddDrawable(panelCollage, panelTransform);
            }

            cel.AddEntity(new Blacklight.Core.Entity
            {
                drawable = collage,
                modelToWorld = AffineMatrix.Identity,
            });

            return cel;
        }
    }
}