# vim:fileencoding=utf-8
# License: GPL v3 Copyright: 2016, Kovid Goyal <kovid at kovidgoyal.net>
from __python__ import bound_methods, hash_literals

from elementmaker import E
from gettext import gettext as _

from book_list.globals import get_session_data
from dom import unique_id
from read_book.prefs.utils import create_button_box
from session import defaults

CONTAINER = unique_id('standalone-scrolling-settings')

# Scroll speeds in lines/sec
MIN_SCROLL_SPEED_AUTO = 0.05
MAX_SCROLL_SPEED_AUTO = 5

MIN_SCROLL_AUTO_DELAY = -1
MAX_SCROLL_AUTO_DELAY = 50

MIN_SCROLL_SPEED_SMOOTH = 5
MAX_SCROLL_SPEED_SMOOTH = 80

def restore_defaults():
    container = get_container()
    for control in container.querySelectorAll('input[name]'):
        val = defaults[control.getAttribute('name')]
        if control.type is 'checkbox':
            control.checked = val
        else:
            control.valueAsNumber = val


def get_container():
    return document.getElementById(CONTAINER)


def change_scroll_speed(amt):
    sd = get_session_data()
    lps = sd.get('lines_per_sec_auto')
    nlps = max(MIN_SCROLL_SPEED_AUTO, min(lps + amt, MAX_SCROLL_SPEED_AUTO))
    if nlps != lps:
        sd.set('lines_per_sec_auto', nlps)
    return nlps


def create_scrolling_panel(container, apply_func, cancel_func):
    container.appendChild(E.div(id=CONTAINER, style='margin: 1rem'))
    container = container.lastChild
    sd = get_session_data()

    def cb(name, text):
        ans = E.input(type='checkbox', name=name)
        if sd.get(name):
            ans.checked = True
        return E.div(style='margin-top:1ex', E.label(ans, '\xa0' + text))

    def spinner(name, text, **kwargs):
        ans = E.input(type='number', name=name, id=name)
        for key, val in Object.entries(kwargs):
            ans[key] = val
        ans.valueAsNumber = sd.get(name, defaults[name])
        return E.label("for"=name, text), ans

    container.appendChild(E.div(style='margin-top:1ex', _('Control how scrolling works in paged mode')))
    container.appendChild(cb(
        'paged_wheel_scrolls_by_screen', _('Mouse wheel scrolls by screen fulls instead of pages')))
    container.appendChild(cb(
        'paged_margin_clicks_scroll_by_screen', _('Clicking on the margins scrolls by screen fulls instead of pages')))
    container.appendChild(cb(
        'paged_taps_scroll_by_screen', _('Tapping scrolls by screen fulls instead of pages')))

    container.appendChild(E.hr())
    container.appendChild(E.div(style='margin-top:1ex', _('Control how smooth scrolling works in flow mode')))
    container.appendChild(cb(
        'scroll_stop_boundaries',
        _('Stop at internal file boundaries when smooth scrolling by holding down the scroll key')
    ))
    container.appendChild(
        E.div(style='display:grid;margin-top:1ex;align-items:center;grid-template-columns:auto min-content;grid-gap:1ex; max-width: 30em',
            *spinner(
                'lines_per_sec_smooth',
                _('Smooth scrolling speed in lines/sec:'),
                step=5,
                min=MIN_SCROLL_SPEED_SMOOTH,
                max=MAX_SCROLL_SPEED_SMOOTH
            ),
            *spinner(
                'lines_per_sec_auto',
                _('Auto scrolling speed in lines/sec:'),
                step=0.05,
                min=MIN_SCROLL_SPEED_AUTO,
                max=MAX_SCROLL_SPEED_AUTO
            ),
            *spinner(
                'scroll_auto_boundary_delay',
                _('Seconds to pause before auto-scrolling past internal file boundaries:'),
                title=_('Use negative values to not auto-scroll past internal file boundaries'),
                step=0.25,
                min=MIN_SCROLL_AUTO_DELAY,
                max=MAX_SCROLL_AUTO_DELAY
            )
        )
    )

    container.appendChild(E.hr())
    container.appendChild(cb('book_scrollbar', _('Show a scrollbar')))

    container.appendChild(create_button_box(restore_defaults, apply_func, cancel_func))


develop = create_scrolling_panel


def commit_scrolling(onchange):
    sd = get_session_data()
    container = get_container()
    changed = False
    for control in container.querySelectorAll('input[name]'):
        name = control.getAttribute('name')
        val = control.checked if control.type is 'checkbox' else control.valueAsNumber
        if val is not sd.get(name) and control.validity.valid:
            sd.set(name, val)
            changed = True
    if changed:
        onchange()