// IAEngine: 2D Game Engine by IA
// Copyright (C) 2025 IASoft (PVT) LTD (oss@iasoft.dev)
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

#include <RenderCore/TextureAtlas.hpp>

namespace ia::iae
{
    RDC_TextureAtlas::RDC_TextureAtlas(IN CONST Vector<Image*> &images)
    {
        if (images.empty())
            return;

        m_atlasSize.x = 0;
        m_atlasSize.y = 0;
        for (const auto &image : images)
        {
            m_atlasSize.x += image->Width;
            if (image->Height > m_atlasSize.y)
                m_atlasSize.y = image->Height;
        }

        m_inverseAtlasSize = {1.0f / ((FLOAT32) m_atlasSize.x), 1.0f / ((FLOAT32) m_atlasSize.y)};

        const auto pixels = new UINT8[m_atlasSize.x * m_atlasSize.y * 4];

        INT32 atlasCursor{0};
        for (const auto &image : images)
        {
            for (INT32 y = 0; y < image->Height; y++)
                ia_memcpy(&pixels[(atlasCursor + (y * m_atlasSize.x)) * 4], &image->Pixels[y * image->Width * 4], image->Width * 4);
            m_texCoordMap[(Handle)(image)] = Vec2(((FLOAT32) atlasCursor) / ((FLOAT32) m_atlasSize.x), 0.0f);
            atlasCursor += image->Width;
        }

        m_texture = new RDC_Texture(RDC_Texture::EType::SAMPLED, m_atlasSize.x, m_atlasSize.y);
        m_texture->SetImageData(pixels);

        delete[] pixels;
    }

    RDC_TextureAtlas::~RDC_TextureAtlas()
    {
        delete m_texture;
    }

    Vec4 RDC_TextureAtlas::GetTextureCoordinates(IN ImageView* imageView, IN INT32 tileIndexX, IN INT32 tileIndexY, IN BOOL flipH,
                                             IN BOOL flipV, IN Vec2 uvOffset)
    {
        const auto &t = m_texCoordMap[(Handle)(imageView->ImagePtr)];
        const auto pX = ((tileIndexX + uvOffset.x) * ((FLOAT32) imageView->TileWidth)) * m_inverseAtlasSize.x;
        const auto pY = ((tileIndexY + uvOffset.y) * ((FLOAT32) imageView->TileHeight)) * m_inverseAtlasSize.y;
        auto texCoords = Vec4(t.x + pX, t.y + pY, imageView->TileWidth * m_inverseAtlasSize.x,
                              imageView->TileHeight * m_inverseAtlasSize.y);
        if (flipH)
        {
            texCoords.x += texCoords.z;
            texCoords.z *= -1;
        }
        if (flipV)
        {
            texCoords.y += texCoords.w;
            texCoords.w *= -1;
        }
        return texCoords;
    }
} // namespace ia::iae