# vim:fileencoding=utf-8
# License: GPL v3 Copyright: 2015, Kovid Goyal <kovid at kovidgoyal.net>
from __python__ import hash_literals, bound_methods

from dom import ensure_id, clear
from elementmaker import E

from book_list.constants import book_list_container_id
from book_list.globals import get_current_query
from book_list.router import push_state
from book_list.library_data import current_library_id, current_virtual_library
from utils import encode_query_with_path


panel_handlers = {}
default_panel_handler = None


def set_panel_handler(panel, handler):
    panel_handlers[panel] = handler


def set_default_panel_handler(handler):
    nonlocal default_panel_handler
    default_panel_handler = handler


def develop_panel(container_id):
    # To use, go to URL:
    # http://localhost:8080/#panel=develop-widgets&widget_module=<module name>
    # Implement the develop(container) method in that module.
    container = document.getElementById(container_id)
    q = get_current_query()
    m = q.widget_module
    if m:
        m = get_module(m)
        if m?.develop:
            m.develop(container)
        else:
            container.textContent = 'The module {} either does not exist or has no develop method.'.format(q.widget_module)

set_panel_handler('develop-widgets', develop_panel)


def currently_showing_panel():
    c = document.getElementById(book_list_container_id)
    return c.dataset.panel


def add_library_info(query):
    if not query.library_id:
        query.library_id = current_library_id()
    if not query.vl:
        if query.vl is None:
            v'delete query.vl'
        else:
            vlid = current_virtual_library()
            if vlid:
                query.vl = vlid

def prepare_query(query, panel):
    q = {k:query[k] for k in (query or {}) if k is not 'panel'}
    if panel is not 'home':
        q.panel = panel
        add_library_info(q)
    return q

def query_as_href(query, panel):
    q = prepare_query(query, panel or 'book_list')
    return encode_query_with_path(q)

def show_panel(panel, query=None, replace=False):
    push_state(prepare_query(query, panel), replace=replace)


def apply_url_state(state):
    panel = state.panel or 'home'
    c = document.getElementById(book_list_container_id)
    clear(c)
    c.appendChild(E.div())
    c.dataset.panel = panel
    handler = panel_handlers[panel] or default_panel_handler
    handler(ensure_id(c.firstChild, 'panel'))


apply_url_state.back_from_current = def back_from_current(current_query):
    q = current_query
    if q.panel:
        if '^' in q.panel:
            q = {k:q[k] for k in q}
            q.panel = q.panel.rpartition('^')[0]
        elif q.panel is 'book_list':
            q = {}
        else:
            q = {'panel':'book_list'}
            add_library_info(q)
    return q
