import os

from nikola.plugin_categories import Task
from nikola import utils


class CopyAssets(Task):
    """Copy theme assets into output."""

    name = "copy_assets"

    def gen_tasks(self):
        """Create tasks to copy the assets of the whole theme chain.

        If a file is present on two themes, use the version
        from the "youngest" theme.
        """

        kw = {
            "themes": self.site.THEMES,
            "output_folder": self.site.config['OUTPUT_FOLDER'],
            "filters": self.site.config['FILTERS'],
        }

        tasks = {}
        for theme_name in kw['themes']:
            src = os.path.join(utils.get_theme_path(theme_name), 'assets')
            dst = os.path.join(kw['output_folder'], 'assets')
            for task in utils.copy_tree(src, dst):
                if task['name'] in tasks:
                    continue
                tasks[task['name']] = task
                task['uptodate'] = [utils.config_changed(kw)]
                task['basename'] = self.name
                yield utils.apply_filters(task, kw['filters'])