#!/usr/bin/env python2
# $Id:$

from pyglet import gl, compat_platform
from pyglet.gl import gl_info
from pyglet.gl import glu_info

class Config(object):
    '''Graphics configuration.

    A Config stores the preferences for OpenGL attributes such as the
    number of auxilliary buffers, size of the colour and depth buffers,
    double buffering, stencilling, multi- and super-sampling, and so on.

    Different platforms support a different set of attributes, so these
    are set with a string key and a value which is integer or boolean.

    :Ivariables:
        `double_buffer` : bool
            Specify the presence of a back-buffer for every color buffer.
        `stereo` : bool
            Specify the presence of separate left and right buffer sets.
        `buffer_size` : int
            Total bits per sample per color buffer.
        `aux_buffers` : int
            The number of auxilliary color buffers.
        `sample_buffers` : int
            The number of multisample buffers.
        `samples` : int
            The number of samples per pixel, or 0 if there are no multisample
            buffers.
        `red_size` : int
            Bits per sample per buffer devoted to the red component.
        `green_size` : int
            Bits per sample per buffer devoted to the green component.
        `blue_size` : int
            Bits per sample per buffer devoted to the blue component.
        `alpha_size` : int
            Bits per sample per buffer devoted to the alpha component.
        `depth_size` : int
            Bits per sample in the depth buffer.
        `stencil_size` : int
            Bits per sample in the stencil buffer.
        `accum_red_size` : int
            Bits per pixel devoted to the red component in the accumulation
            buffer.
        `accum_green_size` : int
            Bits per pixel devoted to the green component in the accumulation
            buffer.
        `accum_blue_size` : int
            Bits per pixel devoted to the blue component in the accumulation
            buffer.
        `accum_alpha_size` : int
            Bits per pixel devoted to the alpha component in the accumulation
            buffer.
    '''

    _attribute_names = [
        'double_buffer',
        'stereo',
        'buffer_size',
        'aux_buffers',
        'sample_buffers',
        'samples',
        'red_size',
        'green_size',
        'blue_size',
        'alpha_size',
        'depth_size',
        'stencil_size',
        'accum_red_size',
        'accum_green_size',
        'accum_blue_size',
        'accum_alpha_size',
        'major_version',
        'minor_version',
        'forward_compatible',
        'debug'
    ]

    major_version = None
    minor_version = None
    forward_compatible = None
    debug = None

    def __init__(self, **kwargs):
        '''Create a template config with the given attributes.

        Specify attributes as keyword arguments, for example::

            template = Config(double_buffer=True)

        '''
        for name in self._attribute_names:
            if name in kwargs:
                setattr(self, name, kwargs[name])
            else:
                setattr(self, name, None)

    def _requires_gl_3(self):
        if self.major_version is not None and self.major_version >= 3:
            return True
        if self.forward_compatible or self.debug:
            return True
        return False

    def get_gl_attributes(self):
        '''Return a list of attributes set on this config.

        :rtype: list of tuple (name, value)
        :return: All attributes, with unset attributes having a value of
            ``None``.
        '''
        return [(name, getattr(self, name)) for name in self._attribute_names]

    def match(self, canvas):
        '''Return a list of matching complete configs for the given canvas.

        :since: pyglet 1.2

        :Parameters:
            `canvas` : `Canvas`
                Display to host contexts created from the config.

        :rtype: list of `CanvasConfig`
        '''
        raise NotImplementedError('abstract')

    def create_context(self, share):
        '''Create a GL context that satisifies this configuration.

        :deprecated: Use `CanvasConfig.create_context`.

        :Parameters:
            `share` : `Context`
                If not None, a context with which to share objects with.

        :rtype: `Context`
        :return: The new context.
        '''
        raise gl.ConfigException(
            'This config cannot be used to create contexts.  '
            'Use Config.match to created a CanvasConfig')

    def is_complete(self):
        '''Determine if this config is complete and able to create a context.

        Configs created directly are not complete, they can only serve
        as templates for retrieving a supported config from the system.
        For example, `pyglet.window.Screen.get_matching_configs` returns
        complete configs.

        :deprecated: Use ``isinstance(config, CanvasConfig)``.

        :rtype: bool
        :return: True if the config is complete and can create a context.
        '''
        return isinstance(self, CanvasConfig)

    def __repr__(self):
        import pprint
        return '%s(%s)' % (self.__class__.__name__, 
                           pprint.pformat(self.get_gl_attributes()))

class CanvasConfig(Config):
    '''OpenGL configuration for a particular canvas.

    Use `Config.match` to obtain an instance of this class.

    :since: pyglet 1.2

    :Ivariables:
        `canvas` : `Canvas`
            The canvas this config is valid on.

    '''
    def __init__(self, canvas, base_config):
        self.canvas = canvas

        self.major_version = base_config.major_version
        self.minor_version = base_config.minor_version
        self.forward_compatible = base_config.forward_compatible
        self.debug = base_config.debug

    def compatible(self, canvas):
        raise NotImplementedError('abstract')

    def create_context(self, share):
        '''Create a GL context that satisifies this configuration.

        :Parameters:
            `share` : `Context`
                If not None, a context with which to share objects with.

        :rtype: `Context`
        :return: The new context.
        '''
        raise NotImplementedError('abstract')

    def is_complete(self):
        return True
 

class ObjectSpace(object):
    def __init__(self):
        # Textures and buffers scheduled for deletion the next time this
        # object space is active.
        self._doomed_textures = []
        self._doomed_buffers = []

class Context(object):
    '''OpenGL context for drawing.

    Use `CanvasConfig.create_context` to create a context.

    :Ivariables:
        `object_space` : `ObjectSpace`
            An object which is shared between all contexts that share
            GL objects.

    '''

    #: Context share behaviour indicating that objects should not be
    #: shared with existing contexts.
    CONTEXT_SHARE_NONE = None

    #: Context share behaviour indicating that objects are shared with
    #: the most recently created context (the default).
    CONTEXT_SHARE_EXISTING = 1
    
    # Used for error checking, True if currently within a glBegin/End block.
    # Ignored if error checking is disabled.
    _gl_begin = False

    # gl_info.GLInfo instance, filled in on first set_current
    _info = None

    # List of (attr, check) for each driver/device-specific workaround that is
    # implemented.  The `attr` attribute on this context is set to the result
    # of evaluating `check(gl_info)` the first time this context is used.
    _workaround_checks = [
        # GDI Generic renderer on Windows does not implement
        # GL_UNPACK_ROW_LENGTH correctly.
        ('_workaround_unpack_row_length',
         lambda info: info.get_renderer() == 'GDI Generic'),

        # Reportedly segfaults in text_input.py example with
        #   "ATI Radeon X1600 OpenGL Engine"
        # glGenBuffers not exported by
        #   "ATI Radeon X1270 x86/MMX/3DNow!/SSE2"
        #   "RADEON XPRESS 200M Series x86/MMX/3DNow!/SSE2"
        # glGenBuffers not exported by
        #   "Intel 965/963 Graphics Media Accelerator"
        ('_workaround_vbo',
         lambda info: (info.get_renderer().startswith('ATI Radeon X')
                       or info.get_renderer().startswith('RADEON XPRESS 200M')
                       or info.get_renderer() == 
                            'Intel 965/963 Graphics Media Accelerator')),

        # Some ATI cards on OS X start drawing from a VBO before it's written
        # to.  In these cases pyglet needs to call glFinish() to flush the
        # pipeline after updating a buffer but before rendering.
        ('_workaround_vbo_finish',
         lambda info: ('ATI' in info.get_renderer() and 
                       info.have_version(1, 5) and
                       compat_platform == 'darwin')),
    ]

    def __init__(self, config, context_share=None):
        self.config = config
        self.context_share = context_share
        self.canvas = None

        if context_share:
            self.object_space = context_share.object_space
        else:
            self.object_space = ObjectSpace()
    
    def __repr__(self):
        return '%s()' % self.__class__.__name__

    def attach(self, canvas):
        if self.canvas is not None:
            self.detach()
        if not self.config.compatible(canvas):
            raise RuntimeError('Cannot attach %r to %r' % (canvas, self))
        self.canvas = canvas

    def detach(self):
        self.canvas = None

    def set_current(self):
        if not self.canvas:
            raise RuntimeError('Canvas has not been attached')

        # XXX not per-thread
        gl.current_context = self

        # XXX
        gl_info.set_active_context()
        glu_info.set_active_context()

        # Implement workarounds
        if not self._info:
            self._info = gl_info.GLInfo()
            self._info.set_active_context()
            for attr, check in self._workaround_checks:
                setattr(self, attr, check(self._info))

        # Release textures and buffers on this context scheduled for deletion.
        # Note that the garbage collector may introduce a race condition,
        # so operate on a copy of the textures/buffers and remove the deleted
        # items using list slicing (which is an atomic operation)
        if self.object_space._doomed_textures:
            textures = self.object_space._doomed_textures[:]
            textures = (gl.GLuint * len(textures))(*textures)
            gl.glDeleteTextures(len(textures), textures)
            self.object_space._doomed_textures[0:len(textures)] = []
        if self.object_space._doomed_buffers:
            buffers = self.object_space._doomed_buffers[:]
            buffers = (gl.GLuint * len(buffers))(*buffers)
            gl.glDeleteBuffers(len(buffers), buffers)
            self.object_space._doomed_buffers[0:len(buffers)] = []

    def destroy(self):
        '''Release the context.

        The context will not be useable after being destroyed.  Each platform
        has its own convention for releasing the context and the buffer(s)
        that depend on it in the correct order; this should never be called
        by an application.
        '''
        self.detach()

        if gl.current_context is self:
            gl.current_context = None
            gl_info.remove_active_context()

            # Switch back to shadow context.
            if gl._shadow_window is not None:
                gl._shadow_window.switch_to()

    def delete_texture(self, texture_id):
        '''Safely delete a texture belonging to this context.

        Usually, the texture is released immediately using
        ``glDeleteTextures``, however if another context that does not share
        this context's object space is currently active, the deletion will
        be deferred until an appropriate context is activated.

        :Parameters:
            `texture_id` : int
                The OpenGL name of the texture to delete.

        '''
        if self.object_space is gl.current_context.object_space:
            id = gl.GLuint(texture_id)
            gl.glDeleteTextures(1, id)
        else:
            self.object_space._doomed_textures.append(texture_id)

    def delete_buffer(self, buffer_id):
        '''Safely delete a buffer object belonging to this context.

        This method behaves similarly to `delete_texture`, though for
        ``glDeleteBuffers`` instead of ``glDeleteTextures``.

        :Parameters:
            `buffer_id` : int
                The OpenGL name of the buffer to delete.

        :since: pyglet 1.1
        '''
        if self.object_space is gl.current_context.object_space and False:
            id = gl.GLuint(buffer_id)
            gl.glDeleteBuffers(1, id)
        else:
            self.object_space._doomed_buffers.append(buffer_id)

    def get_info(self):
        '''Get the OpenGL information for this context.

        :since: pyglet 1.2

        :rtype: `GLInfo`
        '''
        return self._info
