/*
Copyright (c) 2017-2022 Timur Gafarov

Boost Software License - Version 1.0 - August 17th, 2003
Permission is hereby granted, free of charge, to any person or organization
obtaining a copy of the software and accompanying documentation covered by
this license (the "Software") to use, reproduce, display, distribute,
execute, and transmit the Software, and to prepare derivative works of the
Software, and to permit third-parties to whom the Software is furnished to
do so, all subject to the following:

The copyright notices in the Software and this entire statement, including
the above license grant, this restriction and the following disclaimer,
must be included in all copies of the Software, in whole or in part, and
all derivative works of the Software, unless such copies or derivative
works are solely in the form of machine-executable object code generated by
a source language processor.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.
*/

module dagon.graphics.shapes;

import std.math;

import dlib.core.memory;
import dlib.core.ownership;
import dlib.math.vector;
import dlib.container.array;

import dagon.core.bindings;
import dagon.graphics.drawable;
import dagon.graphics.mesh;

class ShapePlane: Mesh
{
    this(float sx, float sz, uint numTiles, Owner owner)
    {
        super(owner);

        float px = -sx * 0.5f;
        float py = -sz * 0.5f;

        float tileWidth = sx / numTiles;
        float tileHeight = sz / numTiles;

        Vector3f start = Vector3f(px, 0.0f, py);

        uint gridSize = numTiles + 1;

        vertices = New!(Vector3f[])(gridSize * gridSize);
        normals = New!(Vector3f[])(gridSize * gridSize);
        texcoords = New!(Vector2f[])(gridSize * gridSize);

        for (uint i = 0, y = 0; y < gridSize; y++)
        for (uint x = 0; x < gridSize; x++, i++)
        {
            vertices[i] = start + Vector3f(x * tileWidth, 0, y * tileHeight);
            normals[i] = Vector3f(0, 1, 0);
            texcoords[i] = Vector2f(x, y);
        }

        indices = New!(uint[3][])(gridSize * gridSize * 2);

        uint index = 0;
        for (uint y = 0; y < gridSize - 1; y++)
        for (uint x = 0; x < gridSize - 1; x++)
        {
            uint offset = y * gridSize + x;
            indices[index][2] = (offset + 0);
            indices[index][1] = (offset + 1);
            indices[index][0] = (offset + gridSize);

            indices[index+1][2] = (offset + 1);
            indices[index+1][1] = (offset + gridSize + 1);
            indices[index+1][0] = (offset + gridSize);

            index += 2;
        }

        dataReady = true;
        prepareVAO();
    }
}

class ShapeQuad: Owner, Drawable
{
    Vector2f[4] vertices;
    Vector2f[4] texcoords;
    uint[3][2] indices;

    GLuint vao = 0;
    GLuint vbo = 0;
    GLuint tbo = 0;
    GLuint eao = 0;

    this(Owner owner)
    {
        super(owner);

        vertices[0] = Vector2f(0, 1);
        vertices[1] = Vector2f(0, 0);
        vertices[2] = Vector2f(1, 0);
        vertices[3] = Vector2f(1, 1);

        texcoords[0] = Vector2f(0, 1);
        texcoords[1] = Vector2f(0, 0);
        texcoords[2] = Vector2f(1, 0);
        texcoords[3] = Vector2f(1, 1);

        indices[0][0] = 0;
        indices[0][1] = 1;
        indices[0][2] = 2;

        indices[1][0] = 0;
        indices[1][1] = 2;
        indices[1][2] = 3;

        glGenBuffers(1, &vbo);
        glBindBuffer(GL_ARRAY_BUFFER, vbo);
        glBufferData(GL_ARRAY_BUFFER, vertices.length * float.sizeof * 2, vertices.ptr, GL_STATIC_DRAW);

        glGenBuffers(1, &tbo);
        glBindBuffer(GL_ARRAY_BUFFER, tbo);
        glBufferData(GL_ARRAY_BUFFER, texcoords.length * float.sizeof * 2, texcoords.ptr, GL_STATIC_DRAW);

        glGenBuffers(1, &eao);
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, eao);
        glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices.length * uint.sizeof * 3, indices.ptr, GL_STATIC_DRAW);

        glGenVertexArrays(1, &vao);
        glBindVertexArray(vao);
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, eao);

        glEnableVertexAttribArray(VertexAttrib.Vertices);
        glBindBuffer(GL_ARRAY_BUFFER, vbo);
        glVertexAttribPointer(VertexAttrib.Vertices, 2, GL_FLOAT, GL_FALSE, 0, null);

        glEnableVertexAttribArray(VertexAttrib.Texcoords);
        glBindBuffer(GL_ARRAY_BUFFER, tbo);
        glVertexAttribPointer(VertexAttrib.Texcoords, 2, GL_FLOAT, GL_FALSE, 0, null);

        glBindVertexArray(0);
    }

    ~this()
    {
        glDeleteVertexArrays(1, &vao);
        glDeleteBuffers(1, &vbo);
        glDeleteBuffers(1, &tbo);
        glDeleteBuffers(1, &eao);
    }

    void render(GraphicsState* state)
    {
        glDepthMask(0);
        glBindVertexArray(vao);
        glDrawElements(GL_TRIANGLES, cast(uint)indices.length * 3, GL_UNSIGNED_INT, cast(void*)0);
        glBindVertexArray(0);
        glDepthMask(1);
    }
}

class ShapeBox: Mesh
{
    this(Vector3f extents, Owner owner)
    {
        super(owner);

        vertices = New!(Vector3f[])(24);
        normals = New!(Vector3f[])(24);
        texcoords = New!(Vector2f[])(24);
        indices = New!(uint[3][])(12);

        Vector3f pmax = +extents;
        Vector3f pmin = -extents;

        texcoords[0] = Vector2f(1, 0); normals[0] = Vector3f(0,0,1); vertices[0] = Vector3f(pmax.x, pmax.y, pmax.z);
        texcoords[1] = Vector2f(0, 0); normals[1] = Vector3f(0,0,1); vertices[1] = Vector3f(pmin.x, pmax.y, pmax.z);
        texcoords[2] = Vector2f(0, 1); normals[2] = Vector3f(0,0,1); vertices[2] = Vector3f(pmin.x, pmin.y, pmax.z);
        texcoords[3] = Vector2f(1, 1); normals[3] = Vector3f(0,0,1); vertices[3] = Vector3f(pmax.x, pmin.y, pmax.z);
        indices[0][0] = 0; indices[0][1] = 1; indices[0][2] = 2;
        indices[1][0] = 2; indices[1][1] = 3; indices[1][2] = 0;

        texcoords[4] = Vector2f(0, 0); normals[4] = Vector3f(1,0,0); vertices[4] = Vector3f(pmax.x, pmax.y, pmax.z);
        texcoords[5] = Vector2f(0, 1); normals[5] = Vector3f(1,0,0); vertices[5] = Vector3f(pmax.x, pmin.y, pmax.z);
        texcoords[6] = Vector2f(1, 1); normals[6] = Vector3f(1,0,0); vertices[6] = Vector3f(pmax.x, pmin.y, pmin.z);
        texcoords[7] = Vector2f(1, 0); normals[7] = Vector3f(1,0,0); vertices[7] = Vector3f(pmax.x, pmax.y, pmin.z);
        indices[2][0] = 4; indices[2][1] = 5; indices[2][2] = 6;
        indices[3][0] = 6; indices[3][1] = 7; indices[3][2] = 4;

        texcoords[8] = Vector2f(1, 1); normals[8] = Vector3f(0,1,0); vertices[8] = Vector3f(pmax.x, pmax.y, pmax.z);
        texcoords[9] = Vector2f(1, 0); normals[9] = Vector3f(0,1,0); vertices[9] = Vector3f(pmax.x, pmax.y, pmin.z);
        texcoords[10] = Vector2f(0, 0); normals[10] = Vector3f(0,1,0); vertices[10] = Vector3f(pmin.x, pmax.y, pmin.z);
        texcoords[11] = Vector2f(0, 1); normals[11] = Vector3f(0,1,0); vertices[11] = Vector3f(pmin.x, pmax.y, pmax.z);
        indices[4][0] = 8; indices[4][1] = 9; indices[4][2] = 10;
        indices[5][0] = 10; indices[5][1] = 11; indices[5][2] = 8;

        texcoords[12] = Vector2f(1, 0); normals[12] = Vector3f(-1,0,0); vertices[12] = Vector3f(pmin.x, pmax.y, pmax.z);
        texcoords[13] = Vector2f(0, 0); normals[13] = Vector3f(-1,0,0); vertices[13] = Vector3f(pmin.x, pmax.y, pmin.z);
        texcoords[14] = Vector2f(0, 1); normals[14] = Vector3f(-1,0,0); vertices[14] = Vector3f(pmin.x, pmin.y, pmin.z);
        texcoords[15] = Vector2f(1, 1); normals[15] = Vector3f(-1,0,0); vertices[15] = Vector3f(pmin.x, pmin.y, pmax.z);
        indices[6][0] = 12; indices[6][1] = 13; indices[6][2] = 14;
        indices[7][0] = 14; indices[7][1] = 15; indices[7][2] = 12;

        texcoords[16] = Vector2f(0, 1); normals[16] = Vector3f(0,-1,0); vertices[16] = Vector3f(pmin.x, pmin.y, pmin.z);
        texcoords[17] = Vector2f(1, 1); normals[17] = Vector3f(0,-1,0); vertices[17] = Vector3f(pmax.x, pmin.y, pmin.z);
        texcoords[18] = Vector2f(1, 0); normals[18] = Vector3f(0,-1,0); vertices[18] = Vector3f(pmax.x, pmin.y, pmax.z);
        texcoords[19] = Vector2f(0, 0); normals[19] = Vector3f(0,-1,0); vertices[19] = Vector3f(pmin.x, pmin.y, pmax.z);
        indices[8][0] = 16; indices[8][1] = 17; indices[8][2] = 18;
        indices[9][0] = 18; indices[9][1] = 19; indices[9][2] = 16;

        texcoords[20] = Vector2f(0, 1); normals[20] = Vector3f(0,0,-1); vertices[20] = Vector3f(pmax.x, pmin.y, pmin.z);
        texcoords[21] = Vector2f(1, 1); normals[21] = Vector3f(0,0,-1); vertices[21] = Vector3f(pmin.x, pmin.y, pmin.z);
        texcoords[22] = Vector2f(1, 0); normals[22] = Vector3f(0,0,-1); vertices[22] = Vector3f(pmin.x, pmax.y, pmin.z);
        texcoords[23] = Vector2f(0, 0); normals[23] = Vector3f(0,0,-1); vertices[23] = Vector3f(pmax.x, pmax.y, pmin.z);
        indices[10][0] = 20; indices[10][1] = 21; indices[10][2] = 22;
        indices[11][0] = 22; indices[11][1] = 23; indices[11][2] = 20;

        dataReady = true;
        prepareVAO();
    }
    
    this(float hw, float hh, float hd, Owner owner)
    {
        this(Vector3f(hw, hh, hd), owner);
    }
}

enum PI2 = PI * 2.0f;
enum HALF_PI = PI * 0.5f;

Vector2f envMapEquirect(Vector3f dir)
{
    Vector2f uv;
    uv.y = acos(dir.y) / PI;
    uv.x = (PI + atan2(dir.x, dir.z)) / PI2;
    return uv;
}

class ShapeSphere: Mesh
{
    Array!Vector3f daVertices;
    Array!Vector3f daNormals;
    Array!Vector2f daTexcoords;
    Array!(uint[3]) daIndices;

    this(float radius, int slices, int stacks, bool invNormals, Owner owner)
    {
        super(owner);

        float X1, Y1, X2, Y2, Z1, Z2;
        float inc1, inc2, inc3, inc4, inc5, radius1, radius2;
        uint[3] tri;
        uint i = 0;

        float cuts = stacks;
        float invCuts = 1.0f / cuts;
        float heightStep = 2.0f * invCuts;

        float invSlices = 1.0f / slices;
        float angleStep = (2.0f * PI) * invSlices;

        for(int h = 0; h < stacks; h++)
        {
            float h1Norm = cast(float)h * invCuts * 2.0f - 1.0f;
            float h2Norm = cast(float)(h+1) * invCuts * 2.0f - 1.0f;
            float y1 = sin(HALF_PI * h1Norm);
            float y2 = sin(HALF_PI * h2Norm);

            float circleRadius1 = cos(HALF_PI * y1);
            float circleRadius2 = cos(HALF_PI * y2);

            for(int a = 0; a < slices; a++)
            {
                float x1a = sin(angleStep * a) * circleRadius1;
                float z1a = cos(angleStep * a) * circleRadius1;
                float x2a = sin(angleStep * (a + 1)) * circleRadius1;
                float z2a = cos(angleStep * (a + 1)) * circleRadius1;

                float x1b = sin(angleStep * a) * circleRadius2;
                float z1b = cos(angleStep * a) * circleRadius2;
                float x2b = sin(angleStep * (a + 1)) * circleRadius2;
                float z2b = cos(angleStep * (a + 1)) * circleRadius2;

                Vector3f v1 = Vector3f(x1a, y1, z1a);
                Vector3f v2 = Vector3f(x2a, y1, z2a);
                Vector3f v3 = Vector3f(x1b, y2, z1b);
                Vector3f v4 = Vector3f(x2b, y2, z2b);

                Vector3f n1 = v1.normalized;
                Vector3f n2 = v2.normalized;
                Vector3f n3 = v3.normalized;
                Vector3f n4 = v4.normalized;

                daVertices.append(n1 * radius);
                daVertices.append(n2 * radius);
                daVertices.append(n3 * radius);

                daVertices.append(n3 * radius);
                daVertices.append(n2 * radius);
                daVertices.append(n4 * radius);

                float sign = invNormals? -1.0f : 1.0f;

                daNormals.append(n1 * sign);
                daNormals.append(n2 * sign);
                daNormals.append(n3 * sign);

                daNormals.append(n3 * sign);
                daNormals.append(n2 * sign);
                daNormals.append(n4 * sign);

                auto uv1 = Vector2f(0, 1);
                auto uv2 = Vector2f(1, 1);
                auto uv3 = Vector2f(0, 0);
                auto uv4 = Vector2f(1, 0);

                daTexcoords.append(uv1);
                daTexcoords.append(uv2);
                daTexcoords.append(uv3);

                daTexcoords.append(uv3);
                daTexcoords.append(uv2);
                daTexcoords.append(uv4);

                if (invNormals)
                {
                    tri[0] = i+2;
                    tri[1] = i+1;
                    tri[2] = i;
                    daIndices.append(tri);

                    tri[0] = i+5;
                    tri[1] = i+4;
                    tri[2] = i+3;
                    daIndices.append(tri);
                }
                else
                {
                    tri[0] = i;
                    tri[1] = i+1;
                    tri[2] = i+2;
                    daIndices.append(tri);

                    tri[0] = i+3;
                    tri[1] = i+4;
                    tri[2] = i+5;
                    daIndices.append(tri);
                }

                i += 6;
            }
        }

        vertices = New!(Vector3f[])(daVertices.length);
        vertices[] = daVertices.data[];

        normals = New!(Vector3f[])(daNormals.length);
        normals[] = daNormals.data[];

        texcoords = New!(Vector2f[])(daTexcoords.length);
        texcoords[] = daTexcoords.data[];

        indices = New!(uint[3][])(daIndices.length);
        indices[] = daIndices.data[];

        daVertices.free();
        daNormals.free();
        daTexcoords.free();
        daIndices.free();

        dataReady = true;
        prepareVAO();
    }
}

class ShapeDisk: Mesh
{
    this(float radius, uint slices, Owner owner)
    {
        super(owner);
        
        vertices = New!(Vector3f[])(slices + 1);
        normals = New!(Vector3f[])(slices + 1);
        texcoords = New!(Vector2f[])(slices + 1);
        indices = New!(uint[3][])(slices);
        
        float angleStep = (2.0f * PI) / slices;
        float angle = 0.0f;
        uint vi = 0;
        uint i = 0;
        
        vertices[vi] = Vector3f(0.0f, 0.0f, 0.0f);
        normals[vi] = Vector3f(0.0f, 1.0f, 0.0f);
        texcoords[vi] = Vector2f(0.5f, 0.5f);
        vi++;
        
        for(uint s = 0; s < slices; s++)
        {
            float x = cos(angle);
            float z = sin(angle);
            
            vertices[vi] = Vector3f(x, 0.0f, z) * radius;
            normals[vi] = Vector3f(0.0f, 1.0f, 0.0f);
            texcoords[vi] = Vector2f(x * 0.5f + 0.5f, z * 0.5f + 0.5f);
            
            indices[i][0] = 0;
            if (s < slices - 1)
                indices[i][1] = vi + 1;
            else
                indices[i][1] = indices[0][2];
            indices[i][2] = vi;
            
            vi++;
            i++;
            
            angle += angleStep;
        }
        
        dataReady = true;
        prepareVAO();
    }
}

// TODO: ShapeCylinder, ShapeCone, ShapeCapsule