import os, json, re
from glob import glob
from datetime import date
from jinja2 import pass_context
#from jinja2 import contextfilter
from flask import Flask, render_template, make_response, abort, redirect, send_from_directory, request
from .lib.dynamic_snippet_library import DynamicSnippetLibrary

TEMPLATES_DIR = '/web/htdocs'

def create_app(test_config=None):
    app = Flask(
            __name__,
            instance_relative_config=True,
            template_folder=TEMPLATES_DIR
        )
    
    if test_config is None:
        if os.environ.get('FLASK_ENV') == 'development':
            app.config.from_object("config.DevelopmentConfig")
        else:
            app.config.from_object("config.ProductionConfig")
    else:
        app.config.from_mapping(test_config)

    try:
        os.makedirs(app.instance_path)
    except OSError:
        pass

    app.jinja_env.filters['DSL.i18n'] = locate_content

    @app.route("/")
    def home():
        return redirect(app.config['SITE_URL'] + '/index.html', code=302)

    @app.route("/<path:template>", methods=["GET","POST"])
    def call_template(template):
        
        if template.endswith('/Welcome.html'):
            return redirect(app.config['SITE_URL'] + '/' + re.sub(r'[^/]+$', '', template), code=301)

        m = re.search(r"([/.])[^/.]*$", template)
        if m and m.group(1) == '/':
            template = re.sub(r"/?$", "/index.jtml", template, count=1)
        elif template.endswith('.html') and os.path.exists(
                os.path.join(TEMPLATES_DIR, template)
            ):
            pass # fall-through to upcoming send_from_directory()
        else:
            template = re.sub(r'h(?=tml$)', 'j', template)

        if not template.endswith('.jtml'):
            return send_from_directory(TEMPLATES_DIR, template)

        m = re.match('([Ee]nglisc?h|[a-z]{2})/', template)
        if m:
            orig_lang = m.group(0)[:-1]
            if 'nglis' in orig_lang:
                # normalize
                orig_lang = 'Englisch'
            langcode = m.group(1)[:2].lower()
        else:
            langcode = ''

        if langcode not in ('de', 'en', 'it', 'fr'):
            orig_lang = ''
            langcode = 'de'
        elif m:
            template = template.split('/', 1)[1]

        layout = gather_layouts_in_ascending_directory_levels(template)
        innermost_layout_name = 'layout.jtml'
        next(layout)
        def layout_finder(name=None):
            nonlocal innermost_layout_name
            if name is not None:
                innermost_layout_name = name
            return layout.send(innermost_layout_name)


        template_lang, mtime_date, found_template = try_templates(template, langcode)

        other_templates_rx = r'(?<=\.)\w\w(?=.jtml$)'
        other_templates = re.sub(other_templates_rx, '*', found_template)
        if '*' in other_templates:
            other_templates = glob(os.path.join(TEMPLATES_DIR, other_templates))
            available_la = []
            for ot in other_templates:
                if m := re.search(other_templates_rx, ot):
                    la = m.group(0)
                else: continue
                available_la.append(la)
            if not('de' in available_la or 'en' in available_la):
                raise RuntimeError(
                        "No other templates: Probed {}. de and en missing".
                        format(', '.join(available_la))

                    )
        else:
            available_la = None

        def check_user_scope():
            # find out if access comes from
            #   - Earth,
            #   - university campus (and if member or student)
            #   - or ourselves, Heidelberg University Library, IT dep.
            ip_address = (
                request.headers.getlist('X-Forwarded-For')[0]
                or request.remote_addr
            )

            return ip_address

        return render_template(found_template,
            layout=layout_finder,
            date=mtime_date,
            DSL=DynamicSnippetLibrary(
                root=app.config['SITE_URL'],
                path=template.replace('.jtml', '.html'),
                available_la=available_la,
                orig_la=orig_lang,
                requested_la=langcode,
                found_la=template_lang,
                passed_args=request.args,
                passed_data=request.form
            ),
            get_real_ip=check_user_scope,
        )

    @app.errorhandler(404)
    def notfound_page(e):
        return make_response(render_template(
            'http404.jtml',
            DSL=DynamicSnippetLibrary(
                root=app.config['SITE_URL'],
                path=request.path,
                orig_la='',
                requested_la='',
                found_la='de',
            )), 404
        )

    return app


def gather_layouts_in_ascending_directory_levels(template):

    layout_name = yield
    if template.endswith("/" + layout_name):
        template, _ = os.path.split(template)

    while True:
        directory, _ = os.path.split(template)

        if not len(directory.strip('/.')):
            layout_name = yield layout_name
            break

        possible_template = os.path.join(directory, layout_name)
        if os.path.exists(os.path.join(TEMPLATES_DIR, possible_template)):
            layout_name = yield possible_template
        template = directory


def try_templates(template, langcode):
    tried = []
    for lang in (langcode, 'en', 'de'):
        suffixed = re.sub(r'(?=\.jtml$)', f'.{lang}', template)
        path = os.path.join(TEMPLATES_DIR, suffixed)
        if os.path.isfile(path):
            template = suffixed
            break
        else:
            tried.append(path)
    else:
        path = os.path.join(TEMPLATES_DIR, template)
        lang = None
        if not os.path.isfile(path):
            abort(404)
    last_update_date = date.fromtimestamp(os.path.getmtime(path)).strftime(
        "%d.%m.%Y" )
    return lang, last_update_date, template


@pass_context
#@contextfilter
def locate_content(ctx, content):
    """
    Show elements with lang or xml:lang attributes, plus their contents,
    only if the requested language matches.
    Always show elements neither lang-specified nor contained in a
    lang-specified ancestor element.
    """
    lang_attr_value_rx = r'\blang=["\']?(\w\w)'
    included = set((i, i) for i in re.findall(lang_attr_value_rx, content))
    la = ctx['DSL'].i18n(**dict(included))
    return re.sub(
        r'<(\w+)[^>]+?' + lang_attr_value_rx + r'[^>]*>(.+?)</\1>',
        lambda m: m.group(0) if m.group(2) == la else '',
        content
    )