//  SPDX-License-Identifier: MIT
//
//  EmulationStation Desktop Edition
//  Renderer_GLES10.cpp
//
//  OpenGL ES 1.0 rendering functions.
//

#if defined(USE_OPENGLES_10)

#include "renderers/Renderer.h"
#include "math/Transform4x4f.h"
#include "Log.h"
#include "Settings.h"

#include <SDL2/SDL.h>
#include <SDL2/SDL_opengles.h>

namespace Renderer
{
    static SDL_GLContext sdlContext = nullptr;
    static GLuint whiteTexture = 0;

    static GLenum convertBlendFactor(const Blend::Factor _blendFactor)
    {
        switch (_blendFactor) {
            case Blend::ZERO:                { return GL_ZERO;                } break;
            case Blend::ONE:                 { return GL_ONE;                 } break;
            case Blend::SRC_COLOR:           { return GL_SRC_COLOR;           } break;
            case Blend::ONE_MINUS_SRC_COLOR: { return GL_ONE_MINUS_SRC_COLOR; } break;
            case Blend::SRC_ALPHA:           { return GL_SRC_ALPHA;           } break;
            case Blend::ONE_MINUS_SRC_ALPHA: { return GL_ONE_MINUS_SRC_ALPHA; } break;
            case Blend::DST_COLOR:           { return GL_DST_COLOR;           } break;
            case Blend::ONE_MINUS_DST_COLOR: { return GL_ONE_MINUS_DST_COLOR; } break;
            case Blend::DST_ALPHA:           { return GL_DST_ALPHA;           } break;
            case Blend::ONE_MINUS_DST_ALPHA: { return GL_ONE_MINUS_DST_ALPHA; } break;
            default:                         { return GL_ZERO;                }
        }
    }

    static GLenum convertTextureType(const Texture::Type _type)
    {
        switch (_type) {
            case Texture::RGBA:  { return GL_RGBA;  } break;
            case Texture::ALPHA: { return GL_ALPHA; } break;
            default:             { return GL_ZERO;  }
        }
    }

    unsigned int getWindowFlags()
    {
        return SDL_WINDOW_OPENGL;
    }

    void setupWindow()
    {
        SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_ES);
        SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 1);
        SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);

        SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 8);
        SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 8);
        SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 8);
        SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
        SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
    }

    bool createContext()
    {
        sdlContext = SDL_GL_CreateContext(getSDLWindow());
        SDL_GL_MakeCurrent(getSDLWindow(), sdlContext);

        std::string vendor = glGetString(GL_VENDOR) ?
                reinterpret_cast<const char*>(glGetString(GL_VENDOR)) : "";
        std::string renderer = glGetString(GL_RENDERER) ?
                reinterpret_cast<const char*>(glGetString(GL_RENDERER)) : "";
        std::string version = glGetString(GL_VERSION) ?
                reinterpret_cast<const char*>(glGetString(GL_VERSION)) : "";
        std::string extensions = glGetString(GL_EXTENSIONS) ?
                reinterpret_cast<const char*>(glGetString(GL_EXTENSIONS)) : "";

        LOG(LogInfo) << "GL vendor: " << vendor;
        LOG(LogInfo) << "GL renderer: " << renderer;
        LOG(LogInfo) << "GL version: " << version;
        LOG(LogInfo) << "EmulationStation renderer: OpenGL ES 1.0";
        LOG(LogInfo) << "Checking available OpenGL extensions...";
        std::string glExts = glGetString(GL_EXTENSIONS) ?
                reinterpret_cast<const char*>(glGetString(GL_EXTENSIONS)) : "";
        LOG(LogInfo) << "GL_OES_texture_npot: " <<
                (extensions.find("GL_OES_texture_npot") !=
                std::string::npos ? "OK" : "MISSING");

        uint8_t data[4] = {255, 255, 255, 255};
        whiteTexture = createTexture(Texture::RGBA, false, true, 1, 1, data);

        GL_CHECK_ERROR(glClearColor(0.0f, 0.0f, 0.0f, 1.0f));
        GL_CHECK_ERROR(glEnable(GL_TEXTURE_2D));
        GL_CHECK_ERROR(glEnable(GL_BLEND));
        GL_CHECK_ERROR(glPixelStorei(GL_PACK_ALIGNMENT, 1));
        GL_CHECK_ERROR(glPixelStorei(GL_UNPACK_ALIGNMENT, 1));
        GL_CHECK_ERROR(glEnableClientState(GL_VERTEX_ARRAY));
        GL_CHECK_ERROR(glEnableClientState(GL_TEXTURE_COORD_ARRAY));
        GL_CHECK_ERROR(glEnableClientState(GL_COLOR_ARRAY));

        return true;
    }

    void destroyContext()
    {
        SDL_GL_DeleteContext(sdlContext);
        sdlContext = nullptr;
    }

    unsigned int createTexture(
            const Texture::Type _type,
            const bool _linear,
            const bool _repeat,
            const unsigned int _width,
            const unsigned int _height,
            void* _data)
    {
        const GLenum type = convertTextureType(_type);
        unsigned int texture;

        GL_CHECK_ERROR(glGenTextures(1, &texture));
        GL_CHECK_ERROR(glBindTexture(GL_TEXTURE_2D, texture));

        GL_CHECK_ERROR(glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, _repeat ?
                GL_REPEAT : GL_CLAMP_TO_EDGE));
        GL_CHECK_ERROR(glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, _repeat ?
                GL_REPEAT : GL_CLAMP_TO_EDGE));
        GL_CHECK_ERROR(glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, _linear ?
                GL_LINEAR : GL_NEAREST));
        GL_CHECK_ERROR(glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST));

        GL_CHECK_ERROR(glTexImage2D(GL_TEXTURE_2D, 0, type, _width, _height, 0, type,
                GL_UNSIGNED_BYTE, _data));

        return texture;
    }

    void destroyTexture(const unsigned int _texture)
    {
        GL_CHECK_ERROR(glDeleteTextures(1, &_texture));
    }

    void updateTexture(
            const unsigned int _texture,
            const Texture::Type _type,
            const unsigned int _x,
            const unsigned _y,
            const unsigned int _width,
            const unsigned int _height,
            void* _data)
    {
        const GLenum type = convertTextureType(_type);

        GL_CHECK_ERROR(glBindTexture(GL_TEXTURE_2D, _texture));
        GL_CHECK_ERROR(glTexSubImage2D(GL_TEXTURE_2D, 0, _x, _y, _width, _height, type,
                GL_UNSIGNED_BYTE, _data));
        GL_CHECK_ERROR(glBindTexture(GL_TEXTURE_2D, whiteTexture));
    }

    void bindTexture(const unsigned int _texture)
    {
        if (_texture == 0)
            GL_CHECK_ERROR(glBindTexture(GL_TEXTURE_2D, whiteTexture));
        else
            GL_CHECK_ERROR(glBindTexture(GL_TEXTURE_2D, _texture));
    }

    void drawLines(
            const Vertex* _vertices,
            const unsigned int _numVertices,
            const Blend::Factor _srcBlendFactor,
            const Blend::Factor _dstBlendFactor)
    {
        GL_CHECK_ERROR(glVertexPointer(2, GL_FLOAT, sizeof(Vertex), &_vertices[0].pos));
        GL_CHECK_ERROR(glTexCoordPointer(2, GL_FLOAT, sizeof(Vertex), &_vertices[0].tex));
        GL_CHECK_ERROR(glColorPointer(4, GL_UNSIGNED_BYTE, sizeof(Vertex), &_vertices[0].col));

        GL_CHECK_ERROR(glBlendFunc(convertBlendFactor(_srcBlendFactor),
                convertBlendFactor(_dstBlendFactor)));

        GL_CHECK_ERROR(glDrawArrays(GL_LINES, 0, _numVertices));
    }

    void drawTriangleStrips(
            const Vertex* _vertices,
            const unsigned int _numVertices,
            const Transform4x4f& _trans,
            const Blend::Factor _srcBlendFactor,
            const Blend::Factor _dstBlendFactor,
            const shaderParameters& _parameters)
    {
        GL_CHECK_ERROR(glVertexPointer(2, GL_FLOAT, sizeof(Vertex), &_vertices[0].pos));
        GL_CHECK_ERROR(glTexCoordPointer(2, GL_FLOAT, sizeof(Vertex), &_vertices[0].tex));
        GL_CHECK_ERROR(glColorPointer(4, GL_UNSIGNED_BYTE, sizeof(Vertex), &_vertices[0].col));

        GL_CHECK_ERROR(glBlendFunc(convertBlendFactor(_srcBlendFactor),
                convertBlendFactor(_dstBlendFactor)));

        GL_CHECK_ERROR(glDrawArrays(GL_TRIANGLE_STRIP, 0, _numVertices));
    }

    void setProjection(const Transform4x4f& _projection)
    {
        GL_CHECK_ERROR(glMatrixMode(GL_PROJECTION));
        GL_CHECK_ERROR(glLoadMatrixf((GLfloat*)&_projection));
    }

    void setMatrix(const Transform4x4f& _matrix)
    {
        Transform4x4f matrix = _matrix;
        matrix.round();

        GL_CHECK_ERROR(glMatrixMode(GL_MODELVIEW));
        GL_CHECK_ERROR(glLoadMatrixf((GLfloat*)&matrix));
    }

    void setViewport(const Rect& _viewport)
    {
        // glViewport starts at the bottom left of the window.
        GL_CHECK_ERROR(glViewport( _viewport.x, getWindowHeight() -
                _viewport.y - _viewport.h, _viewport.w, _viewport.h));
    }

    void setScissor(const Rect& _scissor)
    {
        if ((_scissor.x == 0) && (_scissor.y == 0) && (_scissor.w == 0) && (_scissor.h == 0)) {
            GL_CHECK_ERROR(glDisable(GL_SCISSOR_TEST));
        }
        else {
            // glScissor starts at the bottom left of the window.
            GL_CHECK_ERROR(glScissor(_scissor.x, getWindowHeight() -
                    _scissor.y - _scissor.h, _scissor.w, _scissor.h));
            GL_CHECK_ERROR(glEnable(GL_SCISSOR_TEST));
        }
    }

    void setSwapInterval()
    {
        // vsync.
        if (Settings::getInstance()->getBool("VSync")) {
            // SDL_GL_SetSwapInterval(0) for immediate updates (no vsync, default),
            // 1 for updates synchronized with the vertical retrace,
            // or -1 for late swap tearing.
            // SDL_GL_SetSwapInterval returns 0 on success, -1 on error.
            // if vsync is requested, try normal vsync; if that doesn't work, try late swap tearing
            // if that doesn't work, report an error.
            if (SDL_GL_SetSwapInterval(1) != 0 && SDL_GL_SetSwapInterval(-1) != 0) {
                LOG(LogWarning) << "Tried to enable vsync, but it failed. (" <<
                        SDL_GetError() << ")";
            }
        }
        else {
            SDL_GL_SetSwapInterval(0);
        }
    }

    void swapBuffers()
    {
        SDL_GL_SwapWindow(getSDLWindow());
        GL_CHECK_ERROR(glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT));
    }

} // Renderer::

#endif // USE_OPENGLES_10