namespace TheLabs;

public static class ShapeFactory
{
    public static Mesh CreateTexturedCube()
    {
        float[] vertices = {
            // Format:  X,     Y,     Z,      NX, NY, NZ,     U,  V
        
            // --- Front Face (Normal points +Z: 0, 0, 1) ---
            -0.5f, -0.5f,  0.5f,   0f, 0f, 1f,    0f, 0f, // Bottom-left
            0.5f, -0.5f,  0.5f,   0f, 0f, 1f,    1f, 0f, // Bottom-right
            0.5f,  0.5f,  0.5f,   0f, 0f, 1f,    1f, 1f, // Top-right
            -0.5f,  0.5f,  0.5f,   0f, 0f, 1f,    0f, 1f, // Top-left

            // --- Back Face (Normal points -Z: 0, 0, -1) ---
            -0.5f, -0.5f, -0.5f,   0f, 0f, -1f,   1f, 0f, 
            0.5f, -0.5f, -0.5f,   0f, 0f, -1f,   0f, 0f, 
            0.5f,  0.5f, -0.5f,   0f, 0f, -1f,   0f, 1f, 
            -0.5f,  0.5f, -0.5f,   0f, 0f, -1f,   1f, 1f, 

            // --- Left Face (Normal points -X: -1, 0, 0) ---
            -0.5f, -0.5f, -0.5f,  -1f, 0f, 0f,    0f, 0f, 
            -0.5f, -0.5f,  0.5f,  -1f, 0f, 0f,    1f, 0f, 
            -0.5f,  0.5f,  0.5f,  -1f, 0f, 0f,    1f, 1f, 
            -0.5f,  0.5f, -0.5f,  -1f, 0f, 0f,    0f, 1f, 

            // --- Right Face (Normal points +X: 1, 0, 0) ---
            0.5f, -0.5f, -0.5f,   1f, 0f, 0f,    1f, 0f, 
            0.5f, -0.5f,  0.5f,   1f, 0f, 0f,    0f, 0f, 
            0.5f,  0.5f,  0.5f,   1f, 0f, 0f,    0f, 1f, 
            0.5f,  0.5f, -0.5f,   1f, 0f, 0f,    1f, 1f, 

            // --- Top Face (Normal points +Y: 0, 1, 0) ---
            -0.5f,  0.5f, -0.5f,   0f, 1f, 0f,    0f, 1f, 
            0.5f,  0.5f, -0.5f,   0f, 1f, 0f,    1f, 1f, 
            0.5f,  0.5f,  0.5f,   0f, 1f, 0f,    1f, 0f, 
            -0.5f,  0.5f,  0.5f,   0f, 1f, 0f,    0f, 0f, 

            // --- Bottom Face (Normal points -Y: 0, -1, 0) ---
            -0.5f, -0.5f, -0.5f,   0f, -1f, 0f,   1f, 1f, 
            0.5f, -0.5f, -0.5f,   0f, -1f, 0f,   0f, 1f, 
            0.5f, -0.5f,  0.5f,   0f, -1f, 0f,   0f, 0f, 
            -0.5f, -0.5f,  0.5f,   0f, -1f, 0f,   1f, 0f

        };
        
        uint[] indices = {
            // Front face
            0, 2, 1,
            0, 2, 3,
            // Back face
            4, 5, 6,
            4, 6, 7,
            // Left face
            8, 9, 10,
            8, 10, 11,
            // Right face
            12, 14, 13,
            12, 14, 15,
            // Top face
            16, 17, 18,
            16, 18, 19,
            // Bottom face
            20, 22, 21,
            20, 22, 23
        };
        
        return new Mesh(vertices, indices, Mesh.VertexLayout.PosTexNormal);
    }
    
    public static Mesh CreateColouredCircle()
    {
        float[] vertices = {
            

        };
        
        int segments = 100;
        for (int i = 0; i <= segments; i++)
        {

            float angle = i * 2.0f * MathF.PI / segments;
            float x = 0.5f * MathF.Cos(angle);
            float y = 0.5f * MathF.Sin(angle);
            
            Array.Resize(ref vertices, vertices.Length + 7);
            vertices[^7] = x;
            vertices[^6] = y;
            vertices[^5] = 0f;

        }
        
        return new Mesh(vertices, Mesh.VertexLayout.PosColor);
    }
    
    public static Mesh CreateTexturedCircle()
    {
        var vertices = new List<float>();
        
        int segments = 100;
        
        vertices.Add(0f); // Center X
        vertices.Add(0f); // Center Y
        vertices.Add(0f); // Center Z
        vertices.Add(0.5f); // Center U
        vertices.Add(0.5f); // Center V
        for (int i = 0; i <= segments; i++)
        {

            float angle = i * 2.0f * MathF.PI / segments;
            float x = 0.5f * MathF.Cos(angle);
            float y = 0.5f * MathF.Sin(angle);
            
            vertices.Add(x); // X
            vertices.Add(y); // Y
            vertices.Add(0f); // Z
            vertices.Add((x + 0.5f)); // U
            vertices.Add((y + 0.5f)); // V
            
        }
        
        return new Mesh(vertices.ToArray(), Mesh.VertexLayout.PosTex);
    }

    public static Mesh CreateColorCube()
    {
        float[] vertices = {
            -0.5f, -0.5f,  0.5f,  1f, 0f, 0f, 1f,  0f, 0f, 1f, // Bottom-left
            0.5f, -0.5f,  0.5f,  0f, 1f, 0f, 1f,  0f, 0f, 1f, // Bottom-right
            0.5f,  0.5f,  0.5f,  0f, 0f, 1f, 1f,  0f, 0f, 1f, // Top-right
            -0.5f,  0.5f,  0.5f,  1f, 1f, 0f, 1f,  0f, 0f, 1f, // Top-left

            // Back face (z = -0.5)
            -0.5f, -0.5f, -0.5f,  1f, 0f, 1f, 1f,  0f, 0f, -1f, // Bottom-left
            0.5f, -0.5f, -0.5f,  0f, 1f, 1f, 1f,  0f, 0f, -1f, // Bottom-right
            0.5f,  0.5f, -0.5f,  1f, 1f, 1f, 1f,  0f, 0f, -1f, // Top-right
            -0.5f,  0.5f, -0.5f,  0.5f, 0.5f, 0.5f, 1f,  0f, 0f, -1f, // Top-left
        };
        
        uint[] indices = {
            // Front face
            0, 1, 2,
            2, 3, 0,

            // Back face
            4, 5, 6,
            6, 7, 4,

            // Left face
            4, 0, 3,
            3, 7, 4,

            // Right face
            1, 5, 6,
            6, 2, 1,

            // Top face
            3, 2, 6,
            6, 7, 3,

            // Bottom face
            4, 5, 1,
            1, 0, 4
        };
        
        return new Mesh(vertices, indices, Mesh.VertexLayout.PosColor);
    }

    public static Mesh CreateTexturedCylinder(int segments = 32, float height = 1.0f, float radius = 0.5f)
    {
        var vertices = new List<float>();
        var indices = new List<uint>();
        uint vertexIndex = 0;
        
        float halfHeight = height / 2.0f;
        uint topCenterIndex = vertexIndex;
        vertices.AddRange(new[]
        {
            0.0f, halfHeight, 0.0f, // Position
            0.5f, 0.5f
        }); // Top center vertex
        
        vertexIndex++;
        
        uint topStartIndex = vertexIndex;
        
        for (int i = 0; i <= segments; i++)
        {
            float angle = i * 2.0f * MathF.PI / segments;
            float x = radius * MathF.Cos(angle);
            float z = radius * MathF.Sin(angle);
                
            // UV coordinates are mapped from model space (-0.5 to +0.5)
            // to texture space (0.0 to 1.0)
            float u = x / (radius * 2) + 0.5f;
            float v = z / (radius * 2) + 0.5f;
                
            vertices.AddRange(new[] { x, halfHeight, z, u, v });
            vertexIndex++;
        }
        
        // Add Top Cap Indices (Triangle Fan)
        for (int i = 0; i < segments; i++)
        {
            indices.Add(topCenterIndex);
            indices.Add(topStartIndex + (uint)i);
            indices.Add(topStartIndex + (uint)((i + 1) % segments)); // Wrap around
        }
        
        uint sideStartIndex = vertexIndex;
            
        // Loop from 0 to segments (inclusive) to get (segments + 1)
        // vertices for wrapping the texture seamlessly.
        for (int i = 0; i <= segments; i++)
        {
            float angle = i * 2.0f * MathF.PI / segments;
            float x = radius * MathF.Cos(angle);
            float z = radius * MathF.Sin(angle);
                
            // The U coordinate goes from 0.0 to 1.0 around the cylinder
            float u = (float)i / segments;
                
            // Add Top Side Vertex
            vertices.AddRange(new[] { x, halfHeight, z, u, 1.0f }); // V = 1.0 (top)
            vertexIndex++;
                
            // Add Bottom Side Vertex
            vertices.AddRange(new[] { x, -halfHeight, z, u, 0.0f }); // V = 0.0 (bottom)
            vertexIndex++;
        }
        // Add Side Wall Indices (Quad Strip)
        for (int i = 0; i < segments; i++)
        {
            // Each segment has 2 vertices (top, bottom)
            // We reference the vertices we just created.
            uint topCurrent = sideStartIndex + (uint)(i * 2);
            uint bottomCurrent = topCurrent + 1;
            uint topNext = sideStartIndex + (uint)((i + 1) * 2);
            uint bottomNext = topNext + 1;

            // Triangle 1 (CCW)
            indices.Add(topCurrent);
            indices.Add(bottomCurrent);
            indices.Add(topNext);
                
            // Triangle 2 (CCW)
            indices.Add(bottomCurrent);
            indices.Add(bottomNext);
            indices.Add(topNext);
        }

        // --- 4. Create the Mesh ---
        return new Mesh(vertices.ToArray(), indices.ToArray(), Mesh.VertexLayout.PosTex);
    }
    
    
}