import os

from logilab.common import flatten

from cubicweb.vregistry import objectify_selector

from cubicweb.web.views import baseviews

@objectify_selector

def plot_selector(cls, req, rset, *args, **kwargs):

    """accept result set with at least one line and two columns of result

    all columns after second must be of numerical types"""

    if rset is None:

        return 0

    if not len(rset):

        return 0

    if len(rset.rows[0]) < 2:

        return 0

    for etype in rset.description[0]:

        if etype not in ('Int', 'Float'):

            return 0

    return 1

try:

    import matplotlib

    import sys

    if 'matplotlib.backends' not in sys.modules:

        matplotlib.use('Agg')

except ImportError:

    pass

else:

    class PlotView(baseviews.AnyRsetView):

        id = 'plot'

        title = _('generic plot')

        binary = True

        content_type = 'image/png'

        _plot_count = 0

        __select__ = plot_selector()

        def call(self, width=None, height=None):

            # compute dimensions

            if width is None:

                if 'width' in self.req.form:

                    width = int(self.req.form['width'])

                else:

                    width = 500

            if height is None:

                if 'height' in self.req.form:

                    height = int(self.req.form['height'])

                else:

                    height = 400

            dpi = 100.

            # compute data

            abscisses = [row[0] for row in self.rset]

            courbes = []

            nbcols = len(self.rset.rows[0])

            for col in range(1,nbcols):

                courbe = [row[col] for row in self.rset]

                courbes.append(courbe)

            if not courbes:

                raise Exception('no data')

            # plot data

            fig = figure(figsize=(width/dpi, height/dpi), dpi=dpi)

            ax = fig.add_subplot(111)

            colors = 'brgybrgy'

            try:

                float(abscisses[0])

                xlabels = None

            except ValueError:

                xlabels = abscisses

                abscisses = range(len(xlabels))

            for idx,courbe in enumerate(courbes):

                ax.plot(abscisses, courbe, '%sv-' % colors[idx], label=self.rset.description[0][idx+1])

            ax.autoscale_view()

            alldata = flatten(courbes)

            m, M = min(alldata or [0]), max(alldata or [1])

            if m is None: m = 0

            if M is None: M = 0

            margin = float(M-m)/10

            ax.set_ylim(m-margin, M+margin)

            ax.grid(True)

            ax.legend(loc='best')

            if xlabels is not None:

                ax.set_xticks(abscisses)

                ax.set_xticklabels(xlabels)

            try:

                fig.autofmt_xdate()

            except AttributeError:

                # XXX too old version of matplotlib. Ignore safely.

                pass

            # save plot

            filename = self.build_figname()

            fig.savefig(filename, dpi=100)

            img = open(filename, 'rb')

            self.w(img.read())

            img.close()

            os.remove(filename)

        def build_figname(self):

            self.__class__._plot_count += 1

            return '/tmp/burndown_chart_%s_%d.png' % (self.config.appid, self.__class__._plot_count)