"""
Example generation for the scikit learn

Generate the rst files for the examples by iterating over the python
example files.

Files that generate images should start with 'plot'

"""
from time import time
import os
import shutil
import traceback
import glob
import sys
from StringIO import StringIO

import matplotlib
matplotlib.use('Agg')

import token
import tokenize

rst_template = """

.. _example_%(short_fname)s:

%(docstring)s

**Python source code:** :download:`%(fname)s <%(fname)s>`

.. literalinclude:: %(fname)s
    :lines: %(end_row)s-
    """

plot_rst_template = """

.. _example_%(short_fname)s:

%(docstring)s

%(image_list)s

%(stdout)s

**Python source code:** :download:`%(fname)s <%(fname)s>`

.. literalinclude:: %(fname)s
    :lines: %(end_row)s-
    """

# The following strings are used when we have several pictures: we use
# an html div tag that our CSS uses to turn the lists into horizontal
# lists.
HLIST_HEADER = """
.. rst-class:: horizontal

"""

HLIST_IMAGE_TEMPLATE = """
    *

      .. image:: images/%s
            :scale: 47
"""

SINGLE_IMAGE = """
.. image:: images/%s
    :align: center
"""


def extract_docstring(filename):
    """ Extract a module-level docstring, if any
    """
    lines = file(filename).readlines()
    start_row = 0
    if lines[0].startswith('#!'):
        lines.pop(0)
        start_row = 1

    docstring = ''
    first_par = ''
    tokens = tokenize.generate_tokens(lines.__iter__().next)
    for tok_type, tok_content, _, (erow, _), _ in tokens:
        tok_type = token.tok_name[tok_type]
        if tok_type in ('NEWLINE', 'COMMENT', 'NL', 'INDENT', 'DEDENT'):
            continue
        elif tok_type == 'STRING':
            docstring = eval(tok_content)
            # If the docstring is formatted with several paragraphs, extract
            # the first one:
            paragraphs = '\n'.join(line.rstrip()
                              for line in docstring.split('\n')).split('\n\n')
            if len(paragraphs) > 0:
                first_par = paragraphs[0]
        break
    return docstring, first_par, erow + 1 + start_row


def generate_example_rst(app):
    """ Generate the list of examples, as well as the contents of
        examples.
    """
    root_dir = os.path.join(app.builder.srcdir, 'auto_examples')
    example_dir = os.path.abspath(app.builder.srcdir + '/../' + 'examples')
    try:
        plot_gallery = eval(app.builder.config.plot_gallery)
    except TypeError:
        plot_gallery = bool(app.builder.config.plot_gallery)
    if not os.path.exists(example_dir):
        os.makedirs(example_dir)
    if not os.path.exists(root_dir):
        os.makedirs(root_dir)

    # we create an index.rst with all examples
    fhindex = file(os.path.join(root_dir, 'index.rst'), 'w')  
    #Note: The sidebar button has been removed from the examples page for now
    #      due to how it messes up the layout. Will be fixed at a later point
    fhindex.write("""\

.. raw:: html
    
    
    <style type="text/css">
    
    div#sidebarbutton {
        display: none;
    }

    .figure {
        float: left;
        margin: 10px;
        width: auto;
        height: 200px;
        width: 180px;
    }

    .figure img {
        display: inline;
        }

    .figure .caption {
        width: 170px;
        text-align: center !important;
    }
    </style>

Examples
========

.. _examples-index:
""")
    # Here we don't use an os.walk, but we recurse only twice: flat is
    # better than nested.
    generate_dir_rst('.', fhindex, example_dir, root_dir, plot_gallery)
    for dir in sorted(os.listdir(example_dir)):
        if os.path.isdir(os.path.join(example_dir, dir)):
            generate_dir_rst(dir, fhindex, example_dir, root_dir, plot_gallery)
    fhindex.flush()


def generate_dir_rst(dir, fhindex, example_dir, root_dir, plot_gallery):
    """ Generate the rst file for an example directory.
    """
    if not dir == '.':
        target_dir = os.path.join(root_dir, dir)
        src_dir = os.path.join(example_dir, dir)
    else:
        target_dir = root_dir
        src_dir = example_dir
    if not os.path.exists(os.path.join(src_dir, 'README.txt')):
        print 80 * '_'
        print ('Example directory %s does not have a README.txt file'
                        % src_dir)
        print 'Skipping this directory'
        print 80 * '_'
        return
    fhindex.write("""


%s


""" % file(os.path.join(src_dir, 'README.txt')).read())
    if not os.path.exists(target_dir):
        os.makedirs(target_dir)

    def sort_key(a):
        # put last elements without a plot
        if not a.startswith('plot') and a.endswith('.py'):
            return 'zz' + a
        return a
    for fname in sorted(os.listdir(src_dir), key=sort_key):
        if fname.endswith('py'):
            generate_file_rst(fname, target_dir, src_dir, plot_gallery)
            thumb = os.path.join(dir, 'images', 'thumb', fname[:-3] + '.png')
            link_name = os.path.join(dir, fname).replace(os.path.sep, '_')
            fhindex.write('.. figure:: %s\n' % thumb)
            if link_name.startswith('._'):
                link_name = link_name[2:]
            if dir != '.':
                fhindex.write('   :target: ./%s/%s.html\n\n' % (dir,
                                                               fname[:-3]))
            else:
                fhindex.write('   :target: ./%s.html\n\n' % link_name[:-3])
            fhindex.write("""   :ref:`example_%s`

.. toctree::
   :hidden:

   %s/%s

""" % (link_name, dir, fname[:-3]))
    fhindex.write("""
.. raw:: html

    <div style="clear: both"></div>
    """)  # clear at the end of the section


def generate_file_rst(fname, target_dir, src_dir, plot_gallery):
    """ Generate the rst file for a given example.
    """
    base_image_name = os.path.splitext(fname)[0]
    image_fname = '%s_%%s.png' % base_image_name

    this_template = rst_template
    last_dir = os.path.split(src_dir)[-1]
    # to avoid leading . in file names, and wrong names in links
    if last_dir == '.' or last_dir == 'examples':
        last_dir = ''
    else:
        last_dir += '_'
    short_fname = last_dir + fname
    src_file = os.path.join(src_dir, fname)
    example_file = os.path.join(target_dir, fname)
    shutil.copyfile(src_file, example_file)

    # The following is a list containing all the figure names
    figure_list = []

    image_dir = os.path.join(target_dir, 'images')
    thumb_dir = os.path.join(image_dir, 'thumb')
    if not os.path.exists(image_dir):
        os.makedirs(image_dir)
    if not os.path.exists(thumb_dir):
        os.makedirs(thumb_dir)
    image_path = os.path.join(image_dir, image_fname)
    stdout_path = os.path.join(image_dir,
                               'stdout_%s.txt' % base_image_name)
    thumb_file = os.path.join(thumb_dir, fname[:-3] + '.png')
    if plot_gallery and fname.startswith('plot'):
        # generate the plot as png image if file name
        # starts with plot and if it is more recent than an
        # existing image.
        first_image_file = image_path % 1
        if os.path.exists(stdout_path):
            stdout = open(stdout_path).read()
        else:
            stdout = ''

        if (not os.path.exists(first_image_file) or
                os.stat(first_image_file).st_mtime <=
                                    os.stat(src_file).st_mtime):
            # We need to execute the code
            print 'plotting %s' % fname
            t0 = time()
            import matplotlib.pyplot as plt
            plt.close('all')
            cwd = os.getcwd()
            try:
                # First CD in the original example dir, so that any file
                # created by the example get created in this directory
                orig_stdout = sys.stdout
                os.chdir(os.path.dirname(src_file))
                my_stdout = StringIO()
                sys.stdout = my_stdout
                my_globals = {'pl': plt}
                execfile(os.path.basename(src_file), my_globals)
                sys.stdout = orig_stdout
                my_stdout = my_stdout.getvalue()
                if '__doc__' in my_globals:
                    # The __doc__ is often printed in the example, we
                    # don't with to echo it
                    my_stdout = my_stdout.replace(
                                            my_globals['__doc__'],
                                            '')
                my_stdout = my_stdout.strip()
                if my_stdout:
                    stdout = '**Script output**::\n\n  %s\n\n' % (
                        '\n  '.join(my_stdout.split('\n')))
                open(stdout_path, 'w').write(stdout)
                os.chdir(cwd)

                # In order to save every figure we have two solutions :
                # * iterate from 1 to infinity and call plt.fignum_exists(n)
                #   (this requires the figures to be numbered
                #    incrementally: 1, 2, 3 and not 1, 2, 5)
                # * iterate over [fig_mngr.num for fig_mngr in
                #   matplotlib._pylab_helpers.Gcf.get_all_fig_managers()]
                for fig_num in (fig_mngr.num for fig_mngr in
                        matplotlib._pylab_helpers.Gcf.get_all_fig_managers()):
                    # Set the fig_num figure as the current figure as we can't
                    # save a figure that's not the current figure.
                    plt.figure(fig_num)
                    plt.savefig(image_path % fig_num)
                    figure_list.append(image_fname % fig_num)
            except:
                print 80 * '_'
                print '%s is not compiling:' % fname
                traceback.print_exc()
                print 80 * '_'
            finally:
                os.chdir(cwd)
                sys.stdout = orig_stdout

            print " - time elapsed : %.2g sec" % (time() - t0)
        else:
            figure_list = [f[len(image_dir):]
                            for f in glob.glob(image_path % '[1-9]')]
                            #for f in glob.glob(image_path % '*')]

        # generate thumb file
        this_template = plot_rst_template
        from matplotlib import image
        if os.path.exists(first_image_file):
            image.thumbnail(first_image_file, thumb_file, 0.2)

    if not os.path.exists(thumb_file):
        # create something not to replace the thumbnail
        shutil.copy('images/blank_image.png', thumb_file)

    docstring, short_desc, end_row = extract_docstring(example_file)

    # Depending on whether we have one or more figures, we're using a
    # horizontal list or a single rst call to 'image'.
    if len(figure_list) == 1:
        figure_name = figure_list[0]
        image_list = SINGLE_IMAGE % figure_name.lstrip('/')
    else:
        image_list = HLIST_HEADER
        for figure_name in figure_list:
            image_list += HLIST_IMAGE_TEMPLATE % figure_name.lstrip('/')

    f = open(os.path.join(target_dir, fname[:-2] + 'rst'), 'w')
    f.write(this_template % locals())
    f.flush()


def setup(app):
    app.connect('builder-inited', generate_example_rst)
    app.add_config_value('plot_gallery', True, 'html')

    # Sphinx hack: sphinx copies generated images to the build directory
    #  each time the docs are made.  If the desired image name already
    #  exists, it appends a digit to prevent overwrites.  The problem is,
    #  the directory is never cleared.  This means that each time you build
    #  the docs, the number of images in the directory grows.
    #
    # This question has been asked on the sphinx development list, but there
    #  was no response: http://osdir.com/ml/sphinx-dev/2011-02/msg00123.html
    #
    # The following is a hack that prevents this behavior by clearing the
    #  image build directory each time the docs are built.  If sphinx
    #  changes their layout between versions, this will not work (though
    #  it should probably not cause a crash).  Tested successfully
    #  on Sphinx 1.0.7
    build_image_dir = '_build/html/_images'
    if os.path.exists(build_image_dir):
        filelist = os.listdir(build_image_dir)
        for filename in filelist:
            if filename.endswith('png'):
                os.remove(os.path.join(build_image_dir, filename))