#! /usr/bin/env python
from __future__ import print_function
import argparse
import os
import subprocess
import sys
import traceback

from path import Path

from pavelib import assets
from xmodule import static_content as xmodule_static_content


DEFAULT_STATIC_ROOT = '/openedx/staticfiles'
DEFAULT_THEMES_DIR = '/openedx/themes'


def main():
    parser = argparse.ArgumentParser(
        description="Various assets processing/building/collection utility for Open edX"
    )
    subparsers = parser.add_subparsers()

    npm = subparsers.add_parser('npm', help="Copy static assets from node_modules")
    npm.set_defaults(func=run_npm)

    build = subparsers.add_parser('build', help="Build all assets")
    build.add_argument('-e', '--env', choices=['prod', 'dev'], default='prod')
    build.add_argument('--theme-dirs', nargs='+', default=[DEFAULT_THEMES_DIR])
    build.add_argument('--themes', nargs='+', default=['all'])
    build.add_argument('-r', '--static-root', default=DEFAULT_STATIC_ROOT)
    build.add_argument('--systems', nargs='+', default=['lms', 'cms'])
    build.set_defaults(func=run_build)

    xmodule = subparsers.add_parser('xmodule', help="Process assets from xmodule")
    xmodule.set_defaults(func=run_xmodule)

    webpack = subparsers.add_parser('webpack', help="Run webpack")
    webpack.add_argument('-r', '--static-root', default=DEFAULT_STATIC_ROOT)
    webpack.add_argument('-e', '--env', choices=['prod', 'dev'], default='prod')
    webpack.set_defaults(func=run_webpack)

    common = subparsers.add_parser('common', help="Compile static assets for common theme")
    common.add_argument('--systems', nargs='+', default=['lms', 'cms'])
    common.set_defaults(func=run_common)

    themes = subparsers.add_parser('themes', help="Compile static assets for custom themes")
    themes.add_argument('--theme-dirs', nargs='+', default=[DEFAULT_THEMES_DIR])
    themes.add_argument('--themes', nargs='+', default=['all'])
    themes.add_argument('--systems', nargs='+', default=['lms', 'cms'])
    themes.set_defaults(func=run_themes)

    collect = subparsers.add_parser('collect', help="Collect static assets to be served by webserver")
    collect.add_argument('-s', '--settings', default=os.environ.get('SETTINGS'), help="Django settings module")
    collect.add_argument('--systems', nargs='+', choices=['lms', 'cms'], default=['lms', 'cms'], help="Limit collection to lms or cms")
    collect.set_defaults(func=run_collect)

    watch_themes = subparsers.add_parser('watch-themes', help="Watch theme assets for changes and recompile on-the-fly")
    watch_themes.add_argument('-e', '--env', choices=['prod', 'dev'], default='prod', help="Webpack target to run")
    watch_themes.add_argument('--theme-dirs', default=[DEFAULT_THEMES_DIR])
    watch_themes.set_defaults(func=run_watch_themes)

    args = parser.parse_args()
    args.func(args)

def run_build(args):
    run_xmodule(args)
    run_npm(args)
    run_webpack(args)
    run_common(args)
    run_themes(args)

def run_xmodule(args):
    sys.argv[1:] = ['common/static/xmodule']
    xmodule_static_content.main()

def run_npm(args):
    assets.process_npm_assets()

def run_webpack(args):
    os.environ['STATIC_ROOT_LMS'] = args.static_root
    os.environ['STATIC_ROOT_CMS'] = args.static_root
    os.environ['NODE_ENV'] = {
        'prod': 'production',
        'dev': 'development',
    }[args.env]
    subprocess.call([
        'webpack', '--config=webpack.{env}.config.js'.format(env=args.env)
    ])

def run_common(args):
    for system in args.systems:
        print("Compiling {} sass assets from common theme...".format(system))
        assets._compile_sass(system, None, False, False, [])

def run_themes(args):
    for theme_dir in args.theme_dirs:
        local_themes = list_subdirectories(theme_dir) if 'all' in args.themes else args.themes
        for theme in local_themes:
            theme_path = os.path.join(theme_dir, theme)
            if os.path.exists(theme_path):
                for system in args.systems:
                    print("Compiling {} sass assets from theme {}...".format(system, theme_path))
                    assets._compile_sass(system, Path(theme_path), False, False, [])

def run_collect(args):
    assets.collect_assets(args.systems, args.settings)

def run_watch_themes(args):
    """
    Watch static assets for changes and re-compile those changes when
    necessary. This piece of code is heavily inspired from the
    edx-platform/pavelib/assets.py:watch_assets function, which could not be
    used directly because it does not properly read the platform settings
    environment variable.

    Note that this function will only work for watching assets in development
    mode. In production, watching changes does not make much sense anyway.
    """
    observer = assets.Observer()
    for theme_dir in args.theme_dirs:
        print("Watching changes in {}...".format(theme_dir))
        ThemeWatcher(theme_dir).register(observer)
    observer.start()
    try:
        while True:
            observer.join(2)
    except KeyboardInterrupt:
        observer.stop()

def list_subdirectories(path):
    return [subpath for subpath in os.listdir(path) if os.path.isdir(os.path.join(path, subpath))]


class ThemeWatcher(assets.SassWatcher):

    def __init__(self, theme_dir):
        super(ThemeWatcher, self).__init__()
        self.theme_dir = theme_dir

    #pylint: disable=arguments-differ
    def register(self, observer):
        return super(ThemeWatcher, self).register(observer, [self.theme_dir])

    @assets.debounce()
    def on_any_event(self, event):
        components = os.path.relpath(event.src_path, self.theme_dir).split('/')
        try:
            theme = components[0]
            system = components[1]
        except IndexError:
            return
        try:
            print("Detected change:", event.src_path)
            print("\tRecompiling {} theme for {}".format(theme, system))
            assets._compile_sass(system, Path(self.theme_dir) / theme, False, False, [])
            print("\tDone recompiling {} theme for {}".format(theme, system))
        except Exception: # pylint: disable=broad-except
            traceback.print_exc()


if __name__ == '__main__':
    main()