# Copyright (C) 2011-2012  Patrick Totzke <patricktotzke@gmail.com>
# This file is released under the GNU GPL, version 3 or a later revision.
# For further details see the COPYING file

from   datetime             import datetime, timedelta
import email
from   functools            import cached_property
import importlib.util
import itertools
import logging
import mailcap
import os
import re

from configobj import ConfigObj, Section

from .errors    import ConfigError, NoMatchingAccount
from .utils     import read_config
from .utils     import resolve_att
from .theme     import Theme

from ..account              import SendmailAccount
from ..addressbook.abook    import AbookAddressBook
from ..addressbook.external import ExternalAddressbook
from ..helper               import get_xdg_env
from ..utils                import configobj as checks

DEFAULTSPATH = os.path.join(os.path.dirname(__file__), '..', 'defaults')
DATA_DIRS = get_xdg_env('XDG_DATA_DIRS',
                        '/usr/local/share:/usr/share').split(':')

def _pretty_datetime(d):
    """
    translates :class:`datetime` `d` to a "sup-style" human readable string.

    >>> now = datetime.now()
    >>> now.strftime('%c')
    'Sat 31 Mar 2012 14:47:26 '
    >>> _pretty_datetime(now)
    'just now'
    >>> _pretty_datetime(now - timedelta(minutes=1))
    '1min ago'
    >>> _pretty_datetime(now - timedelta(hours=5))
    '5h ago'
    >>> _pretty_datetime(now - timedelta(hours=12))
    '02:54am'
    >>> _pretty_datetime(now - timedelta(days=1))
    'yest 02pm'
    >>> _pretty_datetime(now - timedelta(days=2))
    'Thu 02pm'
    >>> _pretty_datetime(now - timedelta(days=7))
    'Mar 24'
    >>> _pretty_datetime(now - timedelta(days=356))
    'Apr 2011'
    """
    ampm = d.strftime('%p').lower()
    if len(ampm):
        hourfmt = '%I' + ampm
        hourminfmt = '%I:%M' + ampm
    else:
        hourfmt = '%Hh'
        hourminfmt = '%H:%M'

    now = datetime.now()
    today = now.date()
    if d > now + timedelta(seconds = 59):
        string = 'future'
    elif d.date() == today or d > now - timedelta(hours=6):
        delta = datetime.now() - d
        if delta.seconds < 60:
            string = 'just now'
        elif delta.seconds < 3600:
            string = '%dmin ago' % (delta.seconds // 60)
        elif delta.seconds < 6 * 3600:
            string = '%dh ago' % (delta.seconds // 3600)
        else:
            string = d.strftime(hourminfmt)
    elif d.date() == today - timedelta(1):
        string = d.strftime('yest ' + hourfmt)
    elif d.date() > today - timedelta(7):
        string = d.strftime('%a ' + hourfmt)
    elif d.year != today.year:
        string = d.strftime('%b %Y')
    else:
        string = d.strftime('%b %d')

    return string

class SettingsManager:
    """Organizes user settings"""
    def __init__(self):
        self.hooks = None
        self._mailcaps = mailcap.getcaps()
        self._notmuchconfig = None
        self._theme = None
        self._accounts = None
        self._accountmap = None
        self._notmuchconfig = None
        self._config = ConfigObj()
        self._bindings = None

    def reload(self):
        """Reload notmuch and alot config files"""
        self.read_notmuch_config(self._notmuchconfig.filename)
        self.read_config(self._config.filename)

    def read_notmuch_config(self, path):
        """
        parse notmuch's config file
        :param path: path to notmuch's config file
        :type path: str
        """
        spec = os.path.join(DEFAULTSPATH, 'notmuch.rc.spec')
        self._notmuchconfig = read_config(path, spec)

    def _update_bindings(self, newbindings):
        assert isinstance(newbindings, Section)

        self._bindings = ConfigObj(os.path.join(DEFAULTSPATH,
                                                'default.bindings'))
        self._bindings.merge(newbindings)

    def read_config(self, path):
        """
        parse alot's config file
        :param path: path to alot's config file
        :type path: str
        """
        spec = os.path.join(DEFAULTSPATH, 'alot.rc.spec')
        newconfig = read_config(path, spec, report_extra=True, checks={
                'mail_container': checks.mail_container,
                'force_list': checks.force_list,
                'align': checks.align_mode,
                'attrtriple': checks.attr_triple,
                'gpg_key_hint': checks.gpg_key})
        self._config.merge(newconfig)
        self._config.walk(self._expand_config_values)

        hooks_path = os.path.expanduser(self._config.get('hooksfile'))
        if os.path.isfile(hooks_path):
            try:
                spec = importlib.util.spec_from_file_location('hooks', hooks_path)
                self.hooks = importlib.util.module_from_spec(spec)
                spec.loader.exec_module(self.hooks)
            except Exception as e:
                self.hooks = None
                raise ConfigError('Error loading hooks: %s' % str(e)) from e
        else:
            logging.info('Hooks file does not exist')

        if 'bindings' in newconfig:
            self._update_bindings(newconfig['bindings'])

        tempdir = self._config.get('template_dir')
        logging.debug('template directory: `%s`' % tempdir)

        # validate edit_headers_whitelist/blacklist, which depend on each other
        wl = self._config.get('edit_headers_whitelist')
        bl = self._config.get('edit_headers_blacklist')
        if (wl == ['*']) == (bl == ['*']):
            raise ConfigError('Exactly one of "edit_headers_whitelist"',
                              '"edit_headers_blacklist" must be "*"')
        if ('*' in wl and len(wl) > 1) or ('*' in bl and len(bl) > 1):
            raise ConfigError('When "*" is used in "edit_headers_whitelist"/'
                              '"edit_headers_blacklist", it must be the only item.')

        # themes
        themestring = newconfig['theme']
        themes_dir = self._config.get('themes_dir')
        logging.debug('themes directory: `%s`' % themes_dir)

        # if config contains theme string use that
        data_dirs = [os.path.join(d, 'alot/themes') for d in DATA_DIRS]
        if themestring:
            # This is a python for/else loop
            # https://docs.python.org/3/reference/compound_stmts.html#for
            #
            # tl/dr; If the loop loads a theme it breaks. If it doesn't break,
            # then it raises a ConfigError.
            for dir_ in itertools.chain([themes_dir], data_dirs):
                theme_path = os.path.join(dir_, themestring)
                if not os.path.exists(os.path.expanduser(theme_path)):
                    logging.warning('Theme `%s` does not exist.', theme_path)
                else:
                    try:
                        self._theme = Theme(theme_path)
                    except ConfigError as e:
                        raise ConfigError('Theme file `%s` failed '
                                          'validation:\n%s' % (theme_path, e))
                    else:
                        break
            else:
                raise ConfigError('Could not find theme {}, see log for more '
                                  'information'.format(themestring))

        # if still no theme is set, resort to default
        if self._theme is None:
            theme_path = os.path.join(DEFAULTSPATH, 'default.theme')
            self._theme = Theme(theme_path)

        self._accounts = self._parse_accounts(self._config)
        self._accountmap = self._account_table(self._accounts)

    @staticmethod
    def _expand_config_values(section, key):
        """
        Walker function for ConfigObj.walk

        Applies expand_environment_and_home to all configuration values that
        are strings (or strings that are elements of tuples/lists)

        :param section: as passed by ConfigObj.walk
        :param key: as passed by ConfigObj.walk
        """

        def expand_environment_and_home(value):
            """
            Expands environment variables and the home directory (~).

            $FOO and ${FOO}-style environment variables are expanded, if they
            exist. If they do not exist, they are left unchanged.
            The exception are the following $XDG_* variables that are
            expanded to fallback values, if they are empty or not set:
            $XDG_CONFIG_HOME
            $XDG_CACHE_HOME

            :param value: configuration string
            :type value: str
            """
            xdg_vars = {'XDG_CONFIG_HOME': '~/.config',
                        'XDG_CACHE_HOME': '~/.cache'}

            for xdg_name, fallback in xdg_vars.items():
                if xdg_name in value:
                    xdg_value = get_xdg_env(xdg_name, fallback)
                    value = value.replace('$%s' % xdg_name, xdg_value)\
                                 .replace('${%s}' % xdg_name, xdg_value)
            return os.path.expanduser(os.path.expandvars(value))

        value = section[key]

        if isinstance(value, str):
            section[key] = expand_environment_and_home(value)
        elif isinstance(value, (list, tuple)):
            new = list()
            for item in value:
                if isinstance(item, str):
                    new.append(expand_environment_and_home(item))
                else:
                    new.append(item)
            section[key] = new

    @staticmethod
    def _parse_accounts(config):
        """
        read accounts information from config

        :param config: valit alot config
        :type config: `configobj.ConfigObj`
        :returns: list of accounts
        """
        accounts = []
        if 'accounts' in config:
            for acc in config['accounts'].sections:
                accsec = config['accounts'][acc]
                args = dict(config['accounts'][acc].items())

                # create abook for this account
                abook = accsec['abook']
                logging.debug('abook defined: %s', abook)
                if abook['type'] == 'shellcommand':
                    cmd = abook['command']
                    regexp = abook['regexp']
                    if cmd is not None and regexp is not None:
                        ef = abook['shellcommand_external_filtering']
                        args['abook'] = ExternalAddressbook(
                            cmd, regexp, external_filtering=ef)
                    else:
                        msg = 'underspecified abook of type \'shellcommand\':'
                        msg += '\ncommand: %s\nregexp:%s' % (cmd, regexp)
                        raise ConfigError(msg)
                elif abook['type'] == 'abook':
                    contacts_path = abook['abook_contacts_file']
                    args['abook'] = AbookAddressBook(
                        contacts_path, ignorecase=abook['ignorecase'])
                else:
                    del args['abook']

                cmd = args['sendmail_command']
                del args['sendmail_command']
                newacc = SendmailAccount(cmd, **args)
                accounts.append(newacc)
        return accounts

    @staticmethod
    def _account_table(accounts):
        """
        creates a lookup table (emailaddress -> account) for a given list of
        accounts

        :param accounts: list of accounts
        :type accounts: list of `alot.account.Account`
        :returns: hashtable
        :rvalue: dict (str -> `alot.account.Account`)
        """
        accountmap = {}
        for acc in accounts:
            accountmap[acc.address] = acc
            for alias in acc.aliases:
                accountmap[alias] = acc
        return accountmap

    def get(self, key, fallback=None):
        """
        look up global config values from alot's config

        :param key: key to look up
        :type key: str
        :param fallback: fallback returned if key is not present
        :type fallback: str
        :returns: config value with type as specified in the spec-file
        """
        value = None
        if key in self._config:
            value = self._config[key]
            if isinstance(value, Section):
                value = None
        if value is None:
            value = fallback
        return value

    def set(self, key, value):
        """
        setter for global config values

        :param key: config option identifies
        :type key: str
        :param value: option to set
        :type value: depends on the specfile :file:`alot.rc.spec`
        """
        self._config[key] = value

    def get_notmuch_setting(self, section, key, fallback=None):
        """
        look up config values from notmuch's config

        :param section: key is in
        :type section: str
        :param key: key to look up
        :type key: str
        :param fallback: fallback returned if key is not present
        :type fallback: str
        :returns: config value with type as specified in the spec-file
        """
        value = None
        if section in self._notmuchconfig:
            if key in self._notmuchconfig[section]:
                value = self._notmuchconfig[section][key]
        if value is None:
            value = fallback
        return value

    def get_theming_attribute(self, mode, name, part=None):
        """
        looks up theming attribute

        :param mode: ui-mode (e.g. `search`,`thread`...)
        :type mode: str
        :param name: identifier of the atttribute
        :type name: str
        :rtype: urwid.AttrSpec
        """
        colours = int(self._config.get('colourmode'))
        return self._theme.get_attribute(colours, mode, name, part)

    def get_threadline_theming(self, thread):
        """
        looks up theming info a threadline displaying a given thread. This
        wraps around :meth:`~alot.settings.theme.Theme.get_threadline_theming`,
        filling in the current colour mode.

        :param thread: thread to theme
        :type thread: alot.db.thread.Thread
        """
        colours = int(self._config.get('colourmode'))
        return self._theme.get_threadline_theming(thread, colours)

    def get_quote_theming(self):
        colours = int(self._config.get('colourmode'))
        return self._theme.get_quote_theming(colours)

    def get_tagstring_representation(self, tag, onebelow_normal=None,
                                     onebelow_focus=None):
        """
        looks up user's preferred way to represent a given tagstring.

        :param tag: tagstring
        :type tag: str
        :param onebelow_normal: attribute that shines through if unfocussed
        :type onebelow_normal: urwid.AttrSpec
        :param onebelow_focus: attribute that shines through if focussed
        :type onebelow_focus: urwid.AttrSpec

        If `onebelow_normal` or `onebelow_focus` is given these attributes will
        be used as fallbacks for fg/bg values '' and 'default'.

        This returns a dictionary mapping
            :normal: to :class:`urwid.AttrSpec` used if unfocussed
            :focussed: to :class:`urwid.AttrSpec` used if focussed
            :translated: to an alternative string representation
        """
        colourmode = int(self._config.get('colourmode'))
        theme = self._theme
        cfg = self._config
        colours = [1, 16, 256]

        def colourpick(triple):
            """ pick attribute from triple (mono,16c,256c) according to current
            colourmode"""
            if triple is None:
                return None
            return triple[colours.index(colourmode)]

        # global default attributes for tagstrings.
        # These could contain values '' and 'default' which we interpret as
        # "use the values from the widget below"
        default_normal = theme.get_attribute(colourmode, 'global', 'tag')
        default_focus = theme.get_attribute(colourmode, 'global', 'tag_focus')

        # local defaults for tagstring attributes. depend on next lower widget
        fallback_normal = resolve_att(onebelow_normal, default_normal)
        fallback_focus = resolve_att(onebelow_focus, default_focus)

        for sec in cfg['tags'].sections:
            if re.match('^{}$'.format(sec), tag):
                normal = resolve_att(colourpick(cfg['tags'][sec]['normal']),
                                     fallback_normal)
                focus = resolve_att(colourpick(cfg['tags'][sec]['focus']),
                                    fallback_focus)

                translated = cfg['tags'][sec]['translated']
                if translated is None:
                    translated = tag
                translation = cfg['tags'][sec]['translation']
                if translation:
                    translated = re.sub(translation[0], translation[1], tag)
                break
        else:
            normal = fallback_normal
            focus = fallback_focus
            translated = tag

        return {'normal': normal, 'focussed': focus, 'translated': translated}

    def get_hook(self, key):
        """return hook (`callable`) identified by `key`"""
        if self.hooks:
            return getattr(self.hooks, key, None)
        return None

    def get_mapped_input_keysequences(self, mode='global', prefix=''):
        # get all bindings in this mode
        globalmaps, modemaps = self.get_keybindings(mode)
        candidates = list(globalmaps.keys()) + list(modemaps.keys())
        if prefix is not None:
            prefixes = prefix + ' '
            cand = [c for c in candidates if c.startswith(prefixes)]
            if prefix in candidates:
                candidates = cand + [prefix]
            else:
                candidates = cand
        return candidates

    def get_keybindings(self, mode):
        """look up keybindings from `MODE-maps` sections

        :param mode: mode identifier
        :type mode: str
        :returns: dictionaries of key-cmd for global and specific mode
        :rtype: 2-tuple of dicts
        """
        globalmaps, modemaps = {}, {}
        bindings = self._bindings
        # get bindings for mode `mode`
        # retain empty assignations to silence corresponding global mappings
        if mode in bindings.sections:
            for key in bindings[mode].scalars:
                value = bindings[mode][key]
                if isinstance(value, list):
                    value = ','.join(value)
                modemaps[key] = value
        # get global bindings
        # ignore the ones already mapped in mode bindings
        for key in bindings.scalars:
            if key not in modemaps:
                value = bindings[key]
                if isinstance(value, list):
                    value = ','.join(value)
                if value and value != '':
                    globalmaps[key] = value
        # get rid of empty commands left in mode bindings
        for k, v in list(modemaps.items()):
            if not v:
                del modemaps[k]

        return globalmaps, modemaps

    def get_keybinding(self, mode, key):
        """look up keybinding from `MODE-maps` sections

        :param mode: mode identifier
        :type mode: str
        :param key: urwid-style key identifier
        :type key: str
        :returns: a command line to be applied upon keypress
        :rtype: str
        """
        cmdline = None
        bindings = self._bindings
        if key in bindings.scalars:
            cmdline = bindings[key]
        if mode in bindings.sections:
            if key in bindings[mode].scalars:
                value = bindings[mode][key]
                if value:
                    cmdline = value
                else:
                    # to be sure it isn't mapped globally
                    cmdline = None
        # Workaround for ConfigObj misbehaviour. cf issue #500
        # this ensures that we get at least strings only as commandlines
        if isinstance(cmdline, list):
            cmdline = ','.join(cmdline)
        return cmdline

    def get_accounts(self):
        """
        returns known accounts

        :rtype: list of :class:`Account`
        """
        return self._accounts

    def account_matching_address(self, address, return_default=False):
        """returns :class:`Account` for a given email address (str)

        :param str address: address to look up. A realname part will be ignored.
        :param bool return_default: If True and no address can be found, then
            the default account wil be returned.
        :rtype: :class:`Account`
        :raises ~alot.settings.errors.NoMatchingAccount: If no account can be
            found. This includes if return_default is True and there are no
            accounts defined.
        """
        _, address = email.utils.parseaddr(address)
        for account in self.get_accounts():
            if account.matches_address(address):
                return account
        if return_default:
            try:
                return self.get_accounts()[0]
            except IndexError:
                # Fall through
                pass
        raise NoMatchingAccount

    def get_main_addresses(self):
        """returns addresses of known accounts without its aliases"""
        return [a.address for a in self._accounts]

    def get_addressbooks(self, order=None, append_remaining=True):
        """returns list of all defined :class:`AddressBook` objects"""
        order = order or []
        abooks = []
        for a in order:
            if a:
                if a.abook:
                    abooks.append(a.abook)
        if append_remaining:
            for a in self._accounts:
                if a.abook and a.abook not in abooks:
                    abooks.append(a.abook)
        return abooks

    def mailcap_find_match(self, *args, **kwargs):
        """
        Propagates :func:`mailcap.find_match` but caches the mailcap (first
        argument)
        """
        return mailcap.findmatch(self._mailcaps, *args, **kwargs)

    def represent_datetime(self, d):
        """
        turns a given datetime obj into a string representation.
        This will:

        1) look if a fixed 'timestamp_format' is given in the config
        2) check if a 'timestamp_format' hook is defined
        3) use :func:`_pretty_datetime` as fallback
        """

        fixed_format = self.get('timestamp_format')
        if fixed_format:
            rep = d.strftime(fixed_format)
        else:
            format_hook = self.get_hook('timestamp_format')
            if format_hook:
                rep = format_hook(d)
            else:
                rep = _pretty_datetime(d)
        return rep

    def _make_trans_table(self, tab_width, replace_newline):
        table = {}

        # remove C1 control codes
        for i in range(0x80, 0xa0):
            table[i] = None

        # replace C0 control codes with characters for their graphical
        # representations i.e. "control pictures", which start at U+2400
        for i in range(ord(' ')):
            table[i] = 0x2400 + i

        # "delete" character
        table[0x7f] = 0x2421

        # delete LF
        table[ord('\r')] = None

        if replace_newline:
            table[ord('\n')] = ' '
        else:
            # handle CR normally
            del table[ord('\n')]

        # expand tabs
        table[ord('\t')] = ' ' * tab_width

        return table

    @cached_property
    def sanitize_text_table(self):
        return self._make_trans_table(self.get('tabwidth'), False)
    @cached_property
    def sanitize_header_table(self):
        return self._make_trans_table(1, True)