# builtins
import math
import os
import re

# third-party
import markupsafe
import werkzeug
import flask
import peewee # for type checking

# internals
from application import app

import util

def page(**template_params):

    """
    Decorator for endpoint functions to render the content returned by the
    endpoint function within a proper layout.
    Takes keyword arguments that will be passed into the layout template.
    If the returned content is a Renderable, the layout will render it
    with the passed `mode` if any or 'full' mode otherwise.

    ex:
    ```
    @app.route('/some/path/')
    @page(title="Some page")
    def some_endpoint():
        return "Some content"
    ```
    """

    def decorator(f):

        def wrapper(*args, **kwargs):

            params = {
                'site_name': app.config['SITE_NAME'],
                'user': flask.g.user,
                'tls_cipher': flask.g.tls_cipher,
                'client_cert_verified': flask.g.client_cert_verified,
                'client_cert_fingerprint': flask.g.client_cert_fingerprint,
                'client_cert_fingerprint_matched': flask.g.client_cert_fingerprint_matched,
            }
            params.update(template_params)

            if 'format' not in params:
                params['format'] = 'html'

            if 'layout' in kwargs:

                # explicitly chosen layout

                template_candidates = [
                    f'{app.config["THEME"]}/templates/layout/{params["layout"]}.{params["format"]}',
                ]

                if app.config['THEME'] != 'default':
                    template_candidates.append(f'default/templates/layout/{params["layout"]}.{params["format"]}')

            else:

                # choose layout by endpoint name if a fit exists,
                # otherwise default to 'main'.

                template_candidates = [
                    f'{app.config["THEME"]}/templates/layout/{f.__name__}.{params["format"]}',
                    f'{app.config["THEME"]}/templates/layout/main.{params["format"]}',
                ]

                if app.config['THEME'] != 'default':
                    template_candidates.append(f'default/templates/layout/{f.__name__}.{params["format"]}')
                    template_candidates.append('default/templates/layout/main.{params["format"]}')

            content = f(*args, **kwargs)

            if isinstance(content, werkzeug.Response):
                # if the original return value of the decorated function is
                # a response object, return it as-is – useful for redirects
                return content

            params['content'] = content

            if flask.request.blueprint:
                blueprint = app.blueprints[flask.request.blueprint]
            else:
                blueprint = None


            for menu_name in app.config['MENUS']:

                try:
                    if blueprint and blueprint.menu_exists(menu_name):
                        params[f'menu_{menu_name}'] = blueprint.menu_get(menu_name)
                    elif app.menu_exists(menu_name):
                        params[f'menu_{menu_name}'] = app.menu_get(menu_name)

                except Exception as e:

                    if app.debug:
                        raise

                    app.logger.error(f"Error generating menu '{menu_name}': {str(e)}")

            block_source = blueprint or app

            for block_name in block_source.block_functions:

                try:

                    params[f'block_{block_name}'] = block_source.block_get(block_name)

                except Exception as e:

                    if app.debug:
                        raise

                    app.logger.error(f"(Error generating block '{block_name}': {str(e)}")

            if 'mode' not in params:
                params['mode'] = 'full'

            if 'title' not in params: # means it was passed directly in **template_params

                if  type(content) != str and\
                    hasattr(content, 'title') and\
                    content.title is not None:
                        params['title'] = content.title
                else:
                    params['title'] = None

            if 'title_show' not in params:
                params['title_show'] = True

            status = content.status if isinstance(content, ErrorPage) else 200

            body = flask.render_template(
                template_candidates,
                **params
            )

            response = flask.Response(body, status)

            if params['format'] in app.config['PAGE_CONTENT_TYPES']:
                response.headers['Content-Type'] = app.config['PAGE_CONTENT_TYPES'][params['format']]

            return response

        wrapper.__name__ = f.__name__ # avoid name collisions in routing data
        return wrapper

    return decorator

@app.template_test('renderable')
def test_renderable(obj):
    return isinstance(obj, Renderable)

@app.route('/theme/<path:asset>')
def serve_asset(asset):

    asset_parts = asset.split('/')
    filename = asset_parts[-1]
    subdirectory_parts = asset_parts[:-1]
    subdirectory = '/'.join(subdirectory_parts)

    directory_candidates = [
        os.path.join('themes', app.config['THEME'], 'assets', subdirectory)
    ]

    if app.config['THEME'] != 'default':
        directory_candidates.append(os.path.join('themes', 'default', 'assets', subdirectory))

    for directory_candidate in directory_candidates:

        path_candidate = os.path.join(directory_candidate, filename)

        if os.path.exists(path_candidate):
            return flask.send_from_directory(directory_candidate, filename)

    flask.abort(404)

class Renderable(util.ChildAware):

    def __init__(self, extra_classes=None):

        self.extra_classes = extra_classes or []

    @classmethod
    def load(cls, **kwargs):

        # this is essentially an alias for instantiation to keep consistent
        # with Administerable.load
        return cls(**kwargs)

    def template_candidates(self, mode, format):

        candidates = []

        for cls in self.__class__.mro():
            if issubclass(cls, Renderable):
                candidates += [
                    f'{app.config["THEME"]}/templates/renderable/{cls._lowerclass}-{mode}.{format}',
                    f'{app.config["THEME"]}/templates/renderable/{cls._lowerclass}.{format}',
                ]

        if app.config['THEME'] != 'default':
            for cls in self.__class__.mro():
                if issubclass(cls, Renderable):
                    candidates += [
                        f'default/templates/renderable/{self._lowerclass}-{mode}.{format}',
                        f'default/templates/renderable/{self._lowerclass}.{format}',
                    ]

        return candidates

    @property
    def css_classes(self):
        classes = []
        for cls in self.__class__.mro():
            if issubclass(cls, Renderable):
                classes.append(cls._lowerclass)

        return ' '.join([*classes, *self.extra_classes])

    @classmethod
    def view(cls, mode='full', **kwargs):

        @page(mode=mode)
        def wrapped(**kw):

            instance = cls(**kw)

            if not instance.access(mode):
                flask.abort(403)

            return instance

        return wrapped(**kwargs)

    def access(self, mode='full'):
        return True

    def render(self, mode='full', format='html'):

        return markupsafe.Markup(flask.render_template(
            self.template_candidates(mode, format),
            content=self,
            mode=mode,
            format=format,
        ))

class Menu(Renderable):

    def __init__(self, items=None, id=None, **kwargs):

        super().__init__(**kwargs)

        self.items = []
        self.id = id

        if items:
            for item in items:
                self.append(**item)

    def append(self, url=None, label=None, endpoint=None, params=None, classes=None):

        if not url and not endpoint:
            raise TypeError("Menu items MUST include either 'url' or 'endpoint'.")
        if url and endpoint:
            raise TypeError("Menu items MUST include either 'url' or 'endpoint', but not both.")
        if url and params:
            raise TypeError("Menu items with 'url' MUST NOT include 'params', which is for endpoint items only.")
        if not label:
            raise TypeError("Menu items MUST include 'label'.")

        if endpoint:
            if params is None:
                params = {}

            url = flask.url_for(endpoint, **params)

        state = 'inactive'
        if flask.has_request_context():

            if flask.request.url_rule is not None: # ignore requests for which no route exists
                if flask.request.url_rule.endpoint == endpoint:
                    state = 'active'

                elif endpoint != 'frontpage': # determine trailing status, but not for "home" page.

                    if flask.request.path.startswith(url):
                        state = 'trail'
                    else:
                        state = 'inactive'

        self.items.append({
            'url': url,
            'endpoint': endpoint,
            'state': state,
            'label': label,
            'classes': classes
        })

class Pagination(Renderable):

    def __init__(self, items, endpoint, endpoint_params=None, offset=0, limit=None, **kwargs):

        super().__init__(**kwargs)

        self.items_all = items
        self.items_count = len(self.items_all)
        self.offset = offset
        self.limit = limit or app.config['PAGINATION_LIMIT']
        self.page_count = math.ceil(self.items_count / self.limit)
        self.page_current = int(self.offset / self.limit) + 1
        self.page_spread = app.config['PAGINATION_SPREAD']
        if self.page_spread > self.page_count:
            self.page_spread = self.page_count

        # no menu if its just a single page
        if self.page_count <= 1:

            self.items = self.items_all
            self.menu = None

        else:

            if isinstance(items, peewee.Query):

                # if items are actually a database query, we apply offset and limit
                self.items = self.items_all.offset(self.offset).limit(self.limit)

            else:

                # otherwise we do the equivalent for a list/iterable
                if self.offset >= self.items_count:
                    self.offset = self.items_count -1 # go to last item if offset overshoots

                if self.items_count > self.offset + self.limit:
                    self.items = self.items_all[self.offset:self.offset+self.limit]
                else:
                    self.items = self.items_all[self.offset:]

            page_prev = (self.page_current - 1) or 1
            page_next = self.page_current + 1 if self.page_current < self.page_count else self.page_count
            page_range = None
            page_spread_per_side = math.floor(self.page_spread / 2)

            if self.page_current <= page_spread_per_side:

                # range touches start
                page_range = range(1, 1 + self.page_spread)

            elif self.page_current + page_spread_per_side >= self.page_count:

                # range touches end
                page_range = range(self.page_count - self.page_spread + 1, self.page_count + 1)

            else:

                # range in the middle, not touching either end
                page_range = range(
                    self.page_current - math.floor(self.page_spread / 2),
                    self.page_current + math.ceil(self.page_spread / 2)
                )

            if not endpoint_params:
                endpoint_params = {}

            self.menu = Menu()

            self.menu.append(
                endpoint=endpoint,
                label='⏮',
                params = {
                    'offset': 0,
                    **endpoint_params,
                },
                classes='first current-page' if self.page_current == 1 else 'first'
            )

            self.menu.append(
                endpoint=endpoint,
                label='⏴',
                params={
                    'offset': (page_prev - 1) * self.limit,
                    **endpoint_params,
                },
                classes='previous current-page' if self.page_current == 1 else 'previous'
            )

            for page in page_range:

                self.menu.append(
                    endpoint=endpoint,
                    label=page,
                    params={
                        'offset': (page - 1) * self.limit,
                        **endpoint_params,
                    },
                    classes='current-page' if page == self.page_current else ''
                )

            self.menu.append(
                endpoint=endpoint,
                label='⏵',
                params={
                    'offset': (page_next - 1) * self.limit,
                    **endpoint_params,
                },
                classes='next current-page' if self.page_current == self.page_count else 'next'
            )

            self.menu.append(
                endpoint=endpoint,
                label='⏭',
                params={
                    'offset': (self.page_count - 1) * self.limit,
                    **endpoint_params,
                },
                classes='last current-page' if self.page_current == self.page_count else 'last'
            )

class Listing(Renderable):

    def __init__(self, items, offset=0, limit=None, title=None, mode='teaser', menu=None, endpoint=None, endpoint_params=None, item_constructor=None, **kwargs):

        super().__init__(**kwargs)

        self.items = items
        self.title = title
        self.mode = mode
        self.menu = menu

        if endpoint:
            self.pagination = Pagination(items, endpoint, endpoint_params=endpoint_params, offset=offset, limit=limit)
            self.items = self.pagination.items
        else:
            self.pagination = None

        if item_constructor:
            self.items = [item_constructor(item) for item in self.items]

class ErrorPage(Renderable):

    def __init__(self, message, title='Error', moji=None, status=500, **kwargs):

        super().__init__(**kwargs)

        if moji is None:
            if status in app.config['ERROR_CUSTOM_MOJI']:
                moji = app.config['ERROR_CUSTOM_MOJI'][status]
            else:
                moji = '✖'

        # custom messages from config override messages in code
        if status in app.config['ERROR_CUSTOM_MESSAGES']:
            message = app.config['ERROR_CUSTOM_MESSAGES'][status]

        self.message = message
        self.title = title
        self.moji = moji
        self.status = status