/**

 * $Id$

 *

 * Shared functions for all X11-based display drivers.

 *

 * Copyright (c) 2005 Nathan Keynes.

 *

 * 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 2 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.

 */

#include <stdlib.h>

#include <string.h>

#include "display.h"

#include <X11/Xlib.h>

#include <GL/glx.h>

#include "pvr2/pvr2.h"

#include "pvr2/glutil.h"

#include "drivers/video_glx.h"

#include "drivers/video_gl.h"

/**

 * General X11 parameters. The front-end driver is expected to set this up

 * by calling video_glx_init after initializing itself.

 */

Display *video_x11_display = NULL;

Window video_x11_window = 0;

static int glx_version = 100;

static XVisualInfo *glx_visual = NULL;

static GLXFBConfig glx_fbconfig;

static GLXContext glx_context = NULL;

static gboolean glx_is_initialized = FALSE;

static gboolean glx_fbconfig_supported = FALSE;

static gboolean glx_pbuffer_supported = FALSE;

static GLuint glx_pbuffer_texture = 0; 

static void video_glx_swap_buffers( void );

/* Prototypes for pbuffer support methods */

static void glx_pbuffer_init( display_driver_t driver );

static render_buffer_t glx_pbuffer_create_render_buffer( uint32_t width, uint32_t height, GLuint tex_id );

static void glx_pbuffer_destroy_render_buffer( render_buffer_t buffer );

static gboolean glx_pbuffer_set_render_target( render_buffer_t buffer );

static void glx_pbuffer_finish_render( render_buffer_t buffer );

static void glx_pbuffer_display_render_buffer( render_buffer_t buffer );

static void glx_pbuffer_load_frame_buffer( frame_buffer_t frame, render_buffer_t buffer );

static void glx_pbuffer_display_blank( uint32_t colour );

static gboolean glx_pbuffer_read_render_buffer( unsigned char *target, render_buffer_t buffer, int rowstride, int format );

/**

 * Test if a specific extension is supported. From opengl.org

 * @param extension extension name to check for

 * @return TRUE if supported, otherwise FALSE.

 */

gboolean isServerGLXExtensionSupported( Display *display, int screen, 

                                        const char *extension )

{

    const char *extensions = NULL;

    const char *start;

    char *where, *terminator;

    /* Extension names should not have spaces. */

    where = strchr(extension, ' ');

    if (where || *extension == '\0')

        return 0;

    extensions = glXQueryServerString(display, screen, GLX_EXTENSIONS);

    start = extensions;

    for (;;) {

        where = strstr((const char *) start, extension);

        if (!where)

            break;

        terminator = where + strlen(extension);

        if (where == start || *(where - 1) == ' ')

            if (*terminator == ' ' || *terminator == '\0')

                return TRUE;

        start = terminator;

    }

    return FALSE;

}

gboolean video_glx_init( Display *display, int screen )

{

    int major, minor;

    int glx_major, glx_minor, glx_error;

    if( glx_is_initialized ) {

        return TRUE;

    }

    Bool result = XQueryExtension( display, "GLX", &glx_major, &glx_minor, &glx_error ) &&

                  glXQueryVersion( display, &major, &minor );

    if( result == False ) {

        ERROR( "GLX not supported on display" );

        return FALSE;

    }

    glx_version = (major*100) + minor;

#ifdef APPLE_BUILD

    /* fbconfig is broken on at least the 10.5 GLX implementation */

    glx_fbconfig_supported = FALSE;

#else

    glx_fbconfig_supported = (glx_version >= 103 || 

            isServerGLXExtensionSupported(display, screen,

                    "GLX_SGIX_fbconfig") );

#endif

    glx_pbuffer_supported = (glx_version >= 103 ||

            isServerGLXExtensionSupported(display, screen,

                    "GLX_SGIX_pbuffer") );

//    glx_fbconfig_supported = FALSE;

    if( glx_fbconfig_supported ) {

        int nelem;

        int fb_attribs[] = { GLX_DRAWABLE_TYPE, 

                GLX_PBUFFER_BIT|GLX_WINDOW_BIT, 

                GLX_RENDER_TYPE, GLX_RGBA_BIT, 

                GLX_DEPTH_SIZE, 24, 

                GLX_STENCIL_SIZE, 8, 0 };

        GLXFBConfig *configs = glXChooseFBConfig( display, screen, 

                fb_attribs, &nelem );

        if( configs == NULL || nelem == 0 ) {

            /* Try a 16-bit depth buffer and see if it helps */

            fb_attribs[5] = 16;

            configs = glXChooseFBConfig( display, screen, fb_attribs, &nelem );

            if( nelem > 0 ) {

                WARN( "Using a 16-bit depth buffer - expect video glitches" );

            }

        }

        if( configs == NULL || nelem == 0 ) {

            /* Still didn't work. Fallback to 1.2 methods */

            glx_fbconfig_supported = FALSE;

            glx_pbuffer_supported = FALSE;

        } else {

            glx_fbconfig = configs[0];

            glx_visual = glXGetVisualFromFBConfig(display, glx_fbconfig);

            XFree(configs);

        }

    }

    if( !glx_fbconfig_supported ) {

        int attribs[] = { GLX_RGBA, GLX_DEPTH_SIZE, 24, GLX_STENCIL_SIZE, 8, 0 };

        glx_visual = glXChooseVisual( display, screen, attribs );

        if( glx_visual == NULL ) {

            /* Try the 16-bit fallback here too */

            attribs[2] = 16;

            glx_visual = glXChooseVisual( display, screen, attribs );

            if( glx_visual != NULL ) {

                WARN( "Using a 16-bit depth buffer - expect video glitches" );

            }

        }

    }

    if( glx_visual == NULL ) {

        return FALSE;

    }

    glx_is_initialized = TRUE;

    return TRUE;

}

gboolean video_glx_init_context( Display *display, Window window )

{

    if( glx_fbconfig_supported ) {

        glx_context = glXCreateNewContext( display, glx_fbconfig, 

                GLX_RGBA_TYPE, NULL, True );

        if( glx_context == NULL ) {

            ERROR( "Unable to create a GLX Context.");

            return FALSE;

        }

        if( glXMakeCurrent( display, window,

                glx_context ) == False ) {

            ERROR( "Unable to prepare GLX context for drawing" );

            glXDestroyContext( display, glx_context );

            return FALSE;

        }

    } else {

        glx_context = glXCreateContext( display, glx_visual, None, True );

        if( glx_context == NULL ) {

            ERROR( "Unable to create a GLX Context.");

            return FALSE;

        }

        if( glXMakeCurrent( display, window, glx_context ) == False ) {

            ERROR( "Unable to prepare GLX context for drawing" );

            glXDestroyContext( display, glx_context );

            return FALSE;

        }

    }

    if( !glXIsDirect(display, glx_context) ) {

        WARN( "Not using direct rendering - this is likely to be slow" );

    }

    video_x11_display = display;

    video_x11_window = window;

    return TRUE;

}

gboolean video_glx_init_driver( display_driver_t driver )

{

    driver->swap_buffers = video_glx_swap_buffers;

    if( gl_fbo_is_supported() ) { // First preference

        gl_fbo_init(driver);

    } else if( glx_pbuffer_supported ) {

        glx_pbuffer_init(driver);

    } else {

        ERROR( "Unable to create render buffers (requires either EXT_framebuffer_object or GLX 1.3+)" );

        video_glx_shutdown();

        return FALSE;

    }

    return TRUE;

}

void video_glx_shutdown()

{

    //    texcache_gl_shutdown();

    glx_is_initialized = FALSE;

    if( glx_context != NULL ) {

        glXDestroyContext( video_x11_display, glx_context );

        glx_context = NULL;

    }

    if( glx_visual != NULL ) {

        XFree(glx_visual);

        glx_visual = NULL;

    }

}

XVisualInfo *video_glx_get_visual()

{

    return glx_visual;

}

int video_glx_load_font( const gchar *font_name )

{

    int lists;

    XFontStruct *font = XLoadQueryFont(video_x11_display, font_name );

    if (font == NULL)

        return -1;

    lists = glGenLists(96);

    glXUseXFont(font->fid, 32, 96, lists);

    XFreeFont(video_x11_display, font);

    return lists;

}

static void video_glx_swap_buffers( void )

{

    glXSwapBuffers( video_x11_display, video_x11_window );

}

void video_glx_make_window_current( void )

{

    glXMakeCurrent( video_x11_display, video_x11_window, glx_context );

}

// Pbuffer support

/**

 * Construct the initial frame buffers and allocate ids for everything.

 * The render handling driver methods are set to the fbo versions.

 */

static void glx_pbuffer_init( display_driver_t driver ) 

{

    GLint stencil_bits = 0;

    /* Retrieve the number of stencil bits */

    glGetIntegerv( GL_STENCIL_BITS, &stencil_bits );

    driver->capabilities.stencil_bits = stencil_bits;

    glGenTextures( 1, &glx_pbuffer_texture );

    driver->create_render_buffer = glx_pbuffer_create_render_buffer;

    driver->destroy_render_buffer = glx_pbuffer_destroy_render_buffer;

    driver->set_render_target = glx_pbuffer_set_render_target;

    driver->finish_render = glx_pbuffer_finish_render;

    driver->display_render_buffer = glx_pbuffer_display_render_buffer;

    driver->load_frame_buffer = glx_pbuffer_load_frame_buffer;

    driver->display_blank = glx_pbuffer_display_blank;

    driver->read_render_buffer = glx_pbuffer_read_render_buffer;

}

void glx_pbuffer_shutdown()

{

    glDeleteTextures( 1, &glx_pbuffer_texture );

}

static render_buffer_t glx_pbuffer_create_render_buffer( uint32_t width, uint32_t height, GLuint tex_id )

{

    int attribs[] = { GLX_PBUFFER_WIDTH, width, GLX_PBUFFER_HEIGHT, height,

            GLX_PRESERVED_CONTENTS, True, 0 };

    GLXPbuffer pb = glXCreatePbuffer( video_x11_display, glx_fbconfig, attribs );

    if( pb == (GLXPbuffer)NULL ) {

        ERROR( "Unable to create pbuffer" );

        return NULL;

    }

    render_buffer_t buffer = calloc( sizeof(struct render_buffer), 1 );

    buffer->width = width;

    buffer->height = height;

    buffer->buf_id = pb;

    buffer->tex_id = tex_id;

    return buffer;

}

static void glx_pbuffer_destroy_render_buffer( render_buffer_t buffer )

{

    glXDestroyPbuffer( video_x11_display, (GLXPbuffer)buffer->buf_id );

    buffer->buf_id = 0;

    free( buffer );

}

static gboolean glx_pbuffer_set_render_target( render_buffer_t buffer )

{

    glFinish();

    if( glXMakeContextCurrent( video_x11_display, (GLXPbuffer)buffer->buf_id, (GLXPbuffer)buffer->buf_id, glx_context ) == False ) {

        ERROR( "Make context current (pbuffer) failed!" );

    }

    /* setup the gl context */

    glViewport( 0, 0, buffer->width, buffer->height );

    glDrawBuffer(GL_FRONT);

    return TRUE;

}

static void glx_pbuffer_finish_render( render_buffer_t buffer )

{

    glFinish();

    if( buffer->tex_id != 0 ) {

        // The pbuffer should already be the current context, but just in case...

        glXMakeContextCurrent( video_x11_display, (GLXPbuffer)buffer->buf_id, (GLXPbuffer)buffer->buf_id, glx_context );

        glBindTexture( GL_TEXTURE_RECTANGLE_ARB, buffer->tex_id );

        glCopyTexImage2D(GL_TEXTURE_RECTANGLE_ARB, 0, GL_RGBA, 0, 0, buffer->width, buffer->height, 0 );

    }

}

/**

 * Render the texture holding the given buffer to the front window

 * buffer.

 */

static void glx_pbuffer_display_render_buffer( render_buffer_t buffer )

{

    glFinish();

    glReadBuffer( GL_FRONT );

    glXMakeContextCurrent( video_x11_display, (GLXPbuffer)buffer->buf_id, (GLXPbuffer)buffer->buf_id, glx_context );

    glBindTexture( GL_TEXTURE_RECTANGLE_ARB, glx_pbuffer_texture );

    glCopyTexImage2D(GL_TEXTURE_RECTANGLE_ARB, 0, GL_RGBA, 0, 0, buffer->width, buffer->height, 0 );

    video_glx_make_window_current();

    gl_texture_window( buffer->width, buffer->height, glx_pbuffer_texture, buffer->inverted );

}

static void glx_pbuffer_load_frame_buffer( frame_buffer_t frame, render_buffer_t buffer )

{

    glFinish();

    glXMakeContextCurrent( video_x11_display, (GLXPbuffer)buffer->buf_id, (GLXPbuffer)buffer->buf_id, glx_context );

    GLenum type = colour_formats[frame->colour_format].type;

    GLenum format = colour_formats[frame->colour_format].format;

    int bpp = colour_formats[frame->colour_format].bpp;

    int rowstride = (frame->rowstride / bpp) - frame->width;

    gl_reset_state();

    glPixelStorei( GL_UNPACK_ROW_LENGTH, rowstride );

    glRasterPos2f(0.375, frame->height-0.375);

    glPixelZoom( 1.0, 1.0 );

    glDrawPixels( frame->width, frame->height, format, type, frame->data );

    glFlush();

}

static void glx_pbuffer_display_blank( uint32_t colour )

{

    glFinish();

    video_glx_make_window_current();

    gl_display_blank( colour );

}

static gboolean glx_pbuffer_read_render_buffer( unsigned char *target, render_buffer_t buffer, 

                                                int rowstride, int format )

{

    glXMakeCurrent( video_x11_display, (GLXDrawable)buffer->buf_id, glx_context );

    glReadBuffer( GL_FRONT );

    return gl_read_render_buffer( target, buffer, rowstride, format );

}