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

from ajax import ajax_send

defaults = {
    # Book list settings
    'view_mode': 'cover_grid',
    'sort': 'timestamp.desc',  # comma separated list of items of the form: field.order

    # Tag Browser settings
    'partition_method': 'first letter',  # other choices: 'disable', 'partition'
    'collapse_at': 25,  # number of items at which sub-groups are created, 0 to disable
    'dont_collapse': '',  # comma separated list of category names
    'sort_tags_by': 'name', # other choices: popularity, rating
    'hide_empty_categories': 'no',
    'and_search_terms': False,  # how to add search terms to the search expression from the Tag Browser

    # Book reader settings
    'margin_right': 20,
    'margin_left': 20,
    'margin_top': 20,
    'margin_bottom': 20,
    'read_mode': 'paged',
    'max_text_height': 0,
    'max_text_width': 0,
    'cols_per_screen': 1,
}

def storage_available(which):
    which = which or 'localStorage'
    try:
        storage = window[which]
        x = '__storage__test__'
        storage.setItem(x, x)
        storage.removeItem(x)
        return True
    except:
        return False

session_storage = None

class FakeStorage:

    def __init__(self):
        self.data = {}

    def getItem(self, key):
        return self.data[key]

    def setItem(self, key, value):
        if type(value) is not 'string':
            value = JSON.stringify(value)
        self.data[key] = value

    def clear(self):
        self.data = {}

def get_session_storage():
    nonlocal session_storage
    if session_storage is None:
        if storage_available('localStorage'):
            session_storage = window.localStorage
        elif storage_available('sessionStorage'):
            session_storage = window.sessionStorage
            console.error('localStorage not available using sessionStorage instead')
        else:
            session_storage = FakeStorage()
            console.error('sessionStorage and localStorage not available using a temp cache instead')
    return session_storage

class SessionData:

    def __init__(self, global_prefix=None):
        self.global_prefix = global_prefix or 'calibre-session-'
        self.storage = get_session_storage()
        self.overflow_storage = {}
        self.has_overflow = False

    def get(self, key, defval):
        key = self.global_prefix + key
        if self.has_overflow:
            ans = self.overflow_storage[key]
            if ans is undefined:
                ans = self.storage.getItem(key)
        else:
            ans = self.storage.getItem(key)
        if ans is undefined or ans is None:
            if defval is undefined:
                defval = None
            return defval
        return JSON.parse(ans)

    def set(self, key, value):
        key = self.global_prefix + key
        if value is None:
            self.storage.removeItem(key)
            v'delete self.overflow_storage[key]'
            return True
        value = JSON.stringify(value)
        try:
            self.storage.setItem(key, value)
            v'delete self.overflow_storage[key]'
            return True
        except:
            self.overflow_storage[key] = value
            self.has_overflow = True
            console.error('session storage has overflowed, using a temp cache instead')
        return False

    def clear(self):
        self.storage.clear()
        self.overflow_storage = {}
        self.has_overflow = False

def local_storage():
    if not local_storage.storage:
        local_storage.storage = SessionData('calibre-local-')
    return local_storage.storage

class UserSessionData(SessionData):

    def __init__(self, username, saved_data):
        self.prefix = (username or '') + '-'
        self.has_user = bool(username)
        self.username = username
        SessionData.__init__(self)
        self.echo_changes = False
        self.changes = {}
        self.has_changes = False
        self.push_timer_id = None
        if saved_data:
            for key in saved_data:
                self.set(key, saved_data[key])
        self.echo_changes = True

    def defval(self, key):
        return defaults[key]

    def get(self, key, defval):
        if defval is undefined:
            defval = defaults[key]
        return SessionData.get(self, (self.prefix + key), defval)

    def get_library_option(self, library_id, key, defval):
        if not library_id:
            return self.get(key, defval)
        lkey = key + '-||-' + library_id
        if defval is undefined:
            defval = defaults[key]
        return self.get(lkey, defval)

    def set(self, key, value):
        if self.echo_changes and self.has_user:
            self.changes[key] = value
            self.has_changes = True
            if self.push_timer_id is not None:
                clearTimeout(self.push_timer_id)
            self.push_timer_id = setTimeout(self.push_to_server.bind(self), 1000)
        return SessionData.set(self, (self.prefix + key), value)

    def set_library_option(self, library_id, key, value):
        if library_id:
            key = key + '-||-' + library_id
        return self.set(key, value)

    def push_to_server(self):
        if self.has_changes:
            ajax_send('interface-data/set-session-data', self.changes, def(end_type, xhr, ev):
                if end_type is not 'load':
                    console.error('Failed to send session data to server: ' + xhr.error_html)
            )
            self.changes = {}
            self.has_changes = False