using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Ijw.DirectX;
using System.Runtime.InteropServices;
using System.Drawing;

namespace OpenRa.Game.Graphics
{
    class LineRenderer
    {
        Renderer renderer;
        FvfVertexBuffer<Vertex> vertexBuffer;
        IndexBuffer indexBuffer;            /* kindof a waste of space, but the GPU likes indexing, oh well */

        const int linesPerBatch = 1024;

        Vertex[] vertices = new Vertex[2 * linesPerBatch];
        ushort[] indices = new ushort[2 * linesPerBatch];
        int lines = 0;
        int nv = 0, ni = 0;

        public LineRenderer(Renderer renderer)
        {
            this.renderer = renderer;
            vertexBuffer = new FvfVertexBuffer<Vertex>(renderer.Device, vertices.Length, Vertex.Format);
            indexBuffer = new IndexBuffer(renderer.Device, indices.Length);
        }

        public void Flush()
        {
            if (lines > 0)
            {
                renderer.LineShader.Render(() =>
                {
                    vertexBuffer.SetData(vertices);
                    indexBuffer.SetData(indices);
                    renderer.DrawBatch(vertexBuffer, indexBuffer,
                        nv, ni / 2, null, PrimitiveType.LineList);
                });

                nv = 0; ni = 0;
                lines = 0;
            }
        }

        public void DrawLine(float2 start, float2 end, Color startColor, Color endColor)
        {
            indices[ni++] = (ushort)nv;
            
            vertices[nv++] = new Vertex(start,
                new float2(startColor.R / 255.0f, startColor.G / 255.0f),
                new float2(startColor.B / 255.0f, startColor.A / 255.0f));

            indices[ni++] = (ushort)nv;

            vertices[nv++] = new Vertex(end,
                new float2(endColor.R / 255.0f, endColor.G / 255.0f),
                new float2(endColor.B / 255.0f, endColor.A / 255.0f));

            if (++lines >= linesPerBatch)
                Flush();
        }
    }
}