import copy
import datetime
import json
import os
import sys
import threading
from os import path
from urllib.parse import urlparse, urljoin

import xmltodict
import yaml
from bs4 import BeautifulSoup
from flask import Flask, render_template, Response, send_from_directory, request
from flask.helpers import url_for, send_file, make_response
from flask_frozen import Freezer, walk_directory

from src.Feature import Feature
from src.github import assert_valid_git_hub_url
from src.navigation import process_video_nav, process_nav
from src.api import get_api_page
from src.encoder import DateAwareEncoder
from src.externals import process_nav_includes
from src.grammar import get_grammar
from src.markdown.makrdown import jinja_aware_markdown
from src.pages.MyFlatPages import MyFlatPages
from src.pdf import generate_pdf
from src.processors.processors import process_code_blocks
from src.search import build_search_indices
from src.sitemap import generate_sitemap

app = Flask(__name__, static_folder='_assets')
app.config.from_pyfile('mysettings.py')
app.jinja_env.trim_blocks = True
app.jinja_env.lstrip_blocks = True
pages = MyFlatPages(app)
freezer = Freezer(app)
ignore_stdlib = "--ignore-stdlib" in sys.argv
build_mode = False
build_errors = []
url_adapter = app.create_url_adapter(None)

root_folder = path.join(os.path.dirname(__file__))
data_folder = path.join(os.path.dirname(__file__), "data")

_nav_cache = None
_nav_lock = threading.RLock()


def get_site_data():
    data = {}
    for data_file in os.listdir(data_folder):
        if data_file.startswith('_'):
            continue
        if not data_file.endswith(".yml"):
            continue
        data_file_path = path.join(data_folder, data_file)
        with open(data_file_path, encoding="UTF-8") as stream:
            try:
                file_name_without_extension = data_file[:-4] if data_file.endswith(".yml") else data_file
                data[file_name_without_extension] = yaml.load(stream)
            except yaml.YAMLError as exc:
                sys.stderr.write('Cant parse data file ' + data_file + ': ')
                sys.stderr.write(str(exc))
                sys.exit(-1)
            except IOError as exc:
                sys.stderr.write('Cant read data file ' + data_file + ': ')
                sys.stderr.write(str(exc))
                sys.exit(-1)
    return data


site_data = get_site_data()


def get_nav():
    global _nav_cache
    global _nav_lock

    with _nav_lock:
        if _nav_cache is not None:
            nav = _nav_cache
        else:
            nav = get_nav_impl()

        nav = copy.deepcopy(nav)

        if build_mode:
            _nav_cache = copy.deepcopy(nav)

    # NOTE. This call depends on `request.path`, cannot cache
    process_nav(request.path, nav)
    return nav


def get_nav_impl():
    with open(path.join(data_folder, "_nav.yml")) as stream:
        nav = yaml.load(stream)
        nav = process_nav_includes(build_mode, nav)
        return nav


def get_kotlin_features():
    features_dir = path.join(os.path.dirname(__file__), "kotlin-features")
    features = []
    for feature_meta in yaml.load(open(path.join(features_dir, "kotlin-features.yml"))):
        file_path = path.join(features_dir, feature_meta['content_file'])
        with open(file_path, encoding='utf-8') as f:
            content = f.read()
            content = content.replace("\r\n", "\n")
            if file_path.endswith(".md"):
                html_content = BeautifulSoup(jinja_aware_markdown(content, pages), 'html.parser')
                content = process_code_blocks(html_content)
            features.append(Feature(content, feature_meta))
    return features


@app.context_processor
def add_year_to_context():
    return {
        'year': datetime.datetime.now().year
    }


@app.context_processor
def add_data_to_context():
    return {
        'nav': get_nav(),
        'data': site_data,
        'site': {
            'pdf_url': app.config['PDF_URL'],
            'forum_url': app.config['FORUM_URL'],
            'site_github_url': app.config['SITE_GITHUB_URL'],
            'data': site_data,
            'text_using_gradle': app.config['TEXT_USING_GRADLE'],
            'code_baseurl': app.config['CODE_URL']
        }
    }


@app.context_processor
def override_url_for():
    return {'url_for': versioned_url_for}


def versioned_url_for(endpoint, **values):
    if 'BUILD_NUMBER' in os.environ and endpoint == 'static':
        values['build'] = os.environ['BUILD_NUMBER']
        return url_for(endpoint, **values)
    return url_for(endpoint, **values)


@app.route('/data/events.json')
def get_events():
    with open(path.join(data_folder, "events.xml"), encoding="UTF-8") as events_file:
        events = xmltodict.parse(events_file.read())['events']['event']
        return Response(json.dumps(events, cls=DateAwareEncoder), mimetype='application/json')


@app.route('/data/cities.json')
def get_cities():
    return Response(json.dumps(site_data['cities'], cls=DateAwareEncoder), mimetype='application/json')


@app.route('/docs/reference/grammar.html')
def grammar():
    grammar = get_grammar(build_mode)
    if grammar is None:
        return "Grammar file not found", 404
    return render_template('pages/grammar.html', kotlinGrammar=grammar)


@app.route('/docs/videos.html')
def videos_page():
    return render_template('pages/videos.html', videos=process_video_nav(site_data['videos']))


@app.route('/docs/books.html')
def books_page():
    return render_template('pages/books.html')


@app.route('/docs/kotlin-docs.pdf')
def pdf():
    if build_mode:
        return send_file(generate_pdf(build_mode, pages, get_nav()['reference']))
    else:
        return "Not supported in the dev mode, ask in #kotlin-web-site, if you need it"


@app.route('/docs/resources.html')
def resources():
    return render_template('pages/resources.html')


@app.route('/community/')
def community_page():
    return render_template('pages/community.html')


@app.route('/docs/diagnostics/experimental-coroutines')
@app.route('/docs/diagnostics/experimental-coroutines/')
@app.route('/docs/reference/coroutines.html')
def coroutines_redirect():
    return render_template('redirect.html', url=url_for('page', page_path='docs/reference/coroutines-overview'))


@app.route('/docs/tutorials/coroutines-basic-jvm.html')
def coroutines_tutor_redirect():
    return render_template('redirect.html', url=url_for('page', page_path='docs/tutorials/coroutines/coroutines-basic'
                                                                          '-jvm'))

@app.route('/')
def index_page():
    features = get_kotlin_features()
    return render_template('pages/index.html',
                           is_index_page=True,
                           features=features
                           )


def process_page(page_path):
    # get_nav() has side effect to copy and patch files from the `external` folder
    # under site folder. We need it for dev mode to make sure file is up-to-date
    # TODO: extract get_nav and implement the explicit way to avoid side-effects
    get_nav()

    page = pages.get_or_404(page_path)

    if 'date' in page.meta and page['date'] is not None:
        page.meta['formatted_date'] = page.meta['date'].strftime('%d %B %Y')
        if page.meta['formatted_date'].startswith('0'):
            page.meta['formatted_date'] = page.meta['formatted_date'][1:]

    if 'github_edit_url' in page.meta:
        edit_on_github_url = page.meta['github_edit_url']
    else:
        edit_on_github_url = app.config['EDIT_ON_GITHUB_URL'] + app.config['FLATPAGES_ROOT'] + "/" + page_path + \
                             app.config['FLATPAGES_EXTENSION']

    assert_valid_git_hub_url(edit_on_github_url, page_path)

    template = page.meta["layout"] if 'layout' in page.meta else 'default.html'
    if not template.endswith(".html"):
        template += ".html"

    for link in page.parsed_html.select('a'):
        if 'href' not in link.attrs:
            continue

        href = urlparse(urljoin('/' + page_path, link['href']))
        if href.scheme != '':
            continue

        endpoint, params = url_adapter.match(href.path, 'GET', query_args={})
        if endpoint != 'page' and endpoint != 'get_index_page':
            response = app.test_client().get(href.path)
            if response.status_code == 404:
                build_errors.append("Broken link: " + str(href.path) + " on page " + page_path)
            continue

        referenced_page = pages.get(params['page_path'])
        if referenced_page is None:
            build_errors.append("Broken link: " + str(href.path) + " on page " + page_path)
            continue

        if href.fragment == '':
            continue

        ids = []
        for x in referenced_page.parsed_html.select('h1,h2,h3,h4'):
            try:
                ids.append(x['id'])
            except KeyError:
                pass

        for x in referenced_page.parsed_html.select('a'):
            try:
                ids.append(x['name'])
            except KeyError:
                pass

        if href.fragment not in ids:
            build_errors.append("Bad anchor: " + str(href.fragment) + " on page " + page_path)

    if not build_mode and len(build_errors) > 0:
        errors_copy = []

        for item in build_errors:
            errors_copy.append(item)

        build_errors.clear()
        raise Exception("Validation errors " + str(len(errors_copy)) + ":\n\n" +
                        "\n".join(str(item) for item in errors_copy))

    return render_template(
        template,
        page=page,
        baseurl="",
        edit_on_github_url=edit_on_github_url,

    )


@app.route('/community.html')
def community_redirect():
    return render_template('redirect.html', url=url_for('community_page'))


@app.route('/docs/events.html')
def events_redirect():
    return render_template('redirect.html', url=url_for('page', page_path='community/talks'))

@app.route('/docs/reference/compatibility.html')
def compatibility_redirect():
    return render_template('redirect.html', url=url_for('page', page_path='/docs/reference/evolution/components-stability'))

@freezer.register_generator
def page():
    for page in pages:
        yield {'page_path': page.path}


@app.route('/<path:page_path>.html')
def page(page_path):
    return process_page(page_path)


@app.route('/404.html')
def page_404():
    return render_template('pages/404.html')


@freezer.register_generator
def api_page():
    api_folder = path.join(root_folder, 'api')
    for root, dirs, files in os.walk(api_folder):
        for file in files:
            yield {'page_path': path.join(path.relpath(root, api_folder), file).replace(os.sep, '/')}


@app.errorhandler(404)
def page_not_found(e):
    return render_template('pages/404.html'), 404


app.register_error_handler(404, page_not_found)


@app.route('/api/<path:page_path>')
def api_page(page_path):
    if page_path.endswith('.html'):
        return process_api_page(page_path[:-5])
    elif path.basename(page_path) == "package-list":
        return respond_with_package_list(page_path)
    elif not page_path.endswith('/'):
        page_path += '/'
    return process_api_page(page_path + 'index')


def process_api_page(page_path):
    return render_template(
        'api.html',
        page=get_api_page(build_mode, page_path)
    )


def respond_with_package_list(page_path):
    file_path = path.join(root_folder, 'api', page_path)
    if not path.exists(file_path):
        return make_response("package-list not found", 404)
    return send_file(file_path, mimetype="text/plain")


@app.route('/assets/<path:path>')
def asset(path):
    return send_from_directory('assets', path)


@app.route('/assets/images/tutorials/<path:filename>')
def tutorial_img(filename):
    return send_from_directory(path.join('assets', 'images', 'tutorials'), filename)


@freezer.register_generator
def asset():
    for filename in walk_directory(path.join(root_folder, "assets")):
        yield {'path': filename}


@app.route('/<path:page_path>')
def get_index_page(page_path):
    """
    Handle requests which urls don't end with '.html' (for example, '/doc/')

    We don't need any generator here, because such urls are equivalent to the same urls
    with 'index.html' at the end.

    :param page_path: str
    :return: str
    """
    if not page_path.endswith('/'):
        page_path += '/'
    return process_page(page_path + 'index')


@app.after_request
def add_header(request):
    request.headers["Cache-Control"] = "no-cache, no-store, must-revalidate"
    request.headers["Pragma"] = "no-cache"
    request.headers["Expires"] = "0"
    request.headers['Cache-Control'] = 'public, max-age=0'
    return request


if __name__ == '__main__':
    if len(sys.argv) > 1:
        if sys.argv[1] == "build":
            build_mode = True

            urls = freezer.freeze()
            generate_sitemap(urls)
            if len(build_errors) > 0:
                for error in build_errors:
                    sys.stderr.write(error + '\n')
                sys.exit(-1)
        elif sys.argv[1] == "index":
            build_search_indices(freezer._generate_all_urls(), pages)
    else:
        app.run(host="0.0.0.0", debug=True, threaded=True, **{"extra_files": {"/src/"}})